MANAGEMENT OF NON 窶天ITAL WIDE OPEN APEX
MANAGEMENT OF NON VITAL WIDE OPEN APEX INTRODUCTION DEFINITIONS Open apex (Incomplete Rhizogenesis) Induction of apical healing Apexogenesis Maturogenesis Apexification Apexigenesis One-visit apexification ROOT DEVELOPMENT Stages of root development By Nolla By Cvek CAUSES OF OPEN APICES Pulpal injury in teeth with developing roots TYPES OF OPEN APICES 1. Non blunderbuss 2. Blunderbuss PROBLEMS ASSOCIATED WITH INCOMPLETE RHIZOGENESIS DIAGNOSIS AND CASE ASSESSMENT APEXOGENESIS
MATUROGENESIS METHODS FOR THE TREATMENT OF TEETH WITH AN INCOMPLETELY FORMED APEX (OPEN APEX) I. Blunt end or rolled cone (customized cone) II. Short fill technique IV. Apexification
INTRODUCTION The golden rule in the practice of endodontology is to debride and obturate the canals as efficiently and three dimensionally as possible in an amount of time and appointments that are reasonable to the patient. It is reasonable to assume that most endodontists have achieved the necessary skills to manage predictably and comfortably most of the endodontic cases in their practices. However, there are a group of patients that defy predictable routine treatment.
The completion of root development and closure of the apex occurs up to 3 years after eruption of the tooth (1). The treatment of pulpal injury during this period provides a significant challenge for the clinician. Depending upon the vitality of the affected pulp, two approaches are possible apexogenesis or apexification Article 46 Mary Rafter As always, success is related to accurate diagnosis and a full understanding of the biological processes to be facilitated by the treatment. Article 46 Mary Rafter
The group of patients who present with non vital immature apical formation, requires a specially tailored treatment plan, different from other patients, oftentimes requiring much more than 1 year to complete, depending on the degree of apical immaturity.
Before 1966 the clinical management of a “Blunder buss� canal usually required a surgical approach for the placement of an apical seal into the often fragile and flaring apex. Treatment was complicated when patient management required conscious sedation or general anaesthesia, especially with children. Apexification with calcium hydroxide (Ca(OH)2 has proven to be a reliable and most welcome addition to the therapeutic armamentarium since Frank described it in 1966. Article 33 Howard S. Selden (2002) This process of natural apical closure is more biologic and less traumatic than the classic technique of apicoectomy and obturation of the apex with gutta percha or a retrograde amalgam
DEFINITIONS
Open apex (Incomplete Rhizogenesis) Refers to the absence of sufficient root development to provide a conical taper to the canal and is referred to as a blunderbuss canal (this means that the canal is wider toward the apex than near the cervical area) Franklin S. Weine (6th edition 2004). Induction of apical healing Defined as apical closure through formation of mineralized tissue and repair of the periapical tissues. Apexogenesis Apexogenesis is 'a vital pulp therapy procedure performed to encourage continued physiological development and formation of the root end' (2). Maturogenesis has been defined as physiologic root development, not restricted to the apical segment. The continued deposition of dentin occurs throughout the length of the root, providing greater strength and resistance to fracture. Article 34 Rebeca Weisleder and Claudia R. Benitez Apexification . Apexification is defined as 'a method to induce a calcified barrier in a root with an open apex or the continued apical development of an incomplete root in teeth with necrotic pulp' (2). Apexigenesis
One-visit apexification Defined as the the non-surgical condensation of a biocompatible material into the apical end of the root canal. Morse et al. 1990
ROOT DEVELOPMENT Root development begins when enamel and dentin formation has reached the future cementoenamel junction. At this stage the inner and outer enamel epithelium are no longer separated by the stratum intermedium and stellate reticulum, but develop as a two layered epithelial wall to form Hertwig's epithelial root sheath. When the differentiation of radicular cells into odontoblasts has been induced and the first layer of dentin has been laid down, Hertwig's epithelial root sheath begins to disintegrate and lose its continuity and close relationship to the root surface. Its remnants persist as an epithelial network of strands or tubules near Hertwig's epithelial root sheath is responsible for determining the shape of the root or roots. The epithelial diaphragm surrounds the apical opening to the pulp and eventually becomes the apical foramen. An open apex is found in the developing roots of immature teeth until apical closure occurs approximately 3 years after eruption the external surface of the root
STAGES OF ROOT DEVELOPMENT - M. Cvek According to the width of the apical foramen and the length of the root, Cvek has classified 5 stages of root development. Stage 1 Teeth with wide, divergent apical opening and a root length estimated to less than ½ of the final root length. Stage 2 Teeth with wide divergent apical opening, and a root length estimated to ½ of the final root length. Stage 3 Teeth with wide divergent apical opening and a root length estimated to 2/3rd of the final root length. Stage 4 Teeth with wide open apical foramen and nearly completed root length. Stage 5 Teeth with closed apical foramen and completed root development.
STAGES OF ROOT DEVELOPMENT A. B. C. D. E.
less than half of the final root length half of the final root length two third the final root length nearly completed root length closed apical foramen and completed root development
CAUSES OF OPEN APICES
1. Incomplete development The open apex typically occurs when the pulp undergoes necrosis as a result of caries or trauma, before root growth and development are complete (i.e. during stages 1-4) Some other causes of incomplete development are dens in – dente dentin dysplasia (type II)
An open apex can also occasionally form in a mature apex (stage 5) as a result of 2. Extensive apical resorption due to orthodontics, periapical pathosis or trauma 3. Root end resection during periradicular surgery 4. Over-instrumentation
PULPAL INJURY IN TEETH WITH DEVELOPING ROOTS Unfortunately traumatic injuries to young permanent teeth are not uncommon and are said to affect 30% of children (3). The majority of these incidents occurs before root formation is complete (4) in the 8 to 12 year age range and most commonly involve maxillary anterior teeth. These injuries often result in pulpal inflammation or necrosis and subsequent incomplete development of dentinal wall and root apices. The root sheath of Hertwig is usually sensitive to trauma but because of the degree of vascularity and cellularity in the apical region, root formation can continue even in the presence of pulpal inflammation and necrosis (5, 6). Because of the important role of Hertwig's epithelial root sheath in continued root development after pulpal injury, every effort should be made to maintain its viability. It is thought to provide a source of undifferentiated cells that could give rise to further hard tissue formation. It may also protect against the ingrowth of periodontal ligament cells into the root canal, which would result in intracanal bone formation and arrest of root development (7). Complete destruction of Hertwig's epithelial root sheath results in cessation of normal root development. This does not however mean that there is an end to deposition of hard tissue in the region of the root apex. Once the sheath has been destroyed there can be no further differentiation of odontoblasts. However, hard tissue can be formed by cementoblasts that are normally present in the apical region and by fibroblasts of the dental follicle and periodontal ligament that undergo differentiation after the injury to become hard tissue producing cells.
TYPES OF OPEN APICES These can be of two configurations NON BLUNDERBUSS Broadly opened apex (Cylinder – shaped root canals). BLUNDERBUSS Funnel shaped apex (Apical opening can be wider than the coronal root canal orifice (inverted root canal conicity)
Non Blunderbuss -the walls of the canal may be parallel to slightly convergent as the canal exits the root -the apex, therefore can be broad (cylinder shaped) or tapered (convergent)
Blunderbuss -The word ‘blunderbuss’ basically refers to an 18th century weapon with a short and wide barrel. It derives its origin from the Dutch word ‘DONDERBUS’ which means ‘thunder gun’. - The walls of the canal are divergent and flaring, more especially in the buccolingual direction - The apex is funnel shaped and typically wider than the coronal aspect of the canal.
PROBLEMS ASSOCIATED WITH NON VITAL IMMATURE APEX
• Large open apices - convergent - parallel - divergent • Thin dentinal walls - which are susceptible to fracture before, during or after treatment • Frequent periapical lesions - with or without associated apical resorption • Short roots - thus compromising crown-root ratio •
Fractures of crown - compromising esthetics especially in the anterior region - necessitating post endodontic rehabilitation of both crown and root
• Discoloration in long standing cases
DIAGNOSIS AND CASE ASSESSMENT The importance of careful case assessment and accurate pulpal diagnosis in the treatment of immature teeth with pulpal injury cannot be overemphasized. Clinical assessment of pulpal status requires a thorough history of subjective symptoms, careful clinical and radiographic examination and performance of diagnostic tests. In many instances, the patients symptoms are pain, swelling or the appearance of a fistula, and the tooth may be slightly mobile. An accurate pain history must be obtained. The duration and character of the pain and aggravating and relieving factors should be considered. Duration of pain may vary but pain that lasts for more than a brief period (a few seconds) in a tooth with a vital pulp has been thought to be indicative of irreversible pulpitis. When pain is spontaneous and severe, as well as long lasting, this diagnosis is almost certain. If the pain is throbbing in character and the tooth is tender to touch, pulpal necrosis with apical periodontitis or acute abscess is likely. Confirmation from objective tests is necessary. These include visual examination, percussion testing and thermal and electric pulp testing. The presence of a swelling or sinus tract indicates pulpal necrosis and acute or chronic abscess respectively. Tenderness to percussion signifies inflammation in the periapical tissues. Vitality testing in the immature tooth is inherently unreliable as these teeth provide unpredictable responses to pulp testing. Prior to completion of root formation, the sensory plexus of nerves in the subodontoblastic region is not well developed and as the injury itself can lead to erratic responses (9) over reliance on the results of clinical tests of pulp vitality, particularly by the use of electric pulp testing devices, is not recommended (10). Radiographic interpretation can be difficult. The
radiograph may show periapical zone of radiolucency. A radiolucent area normally surrounds the developing open apex of an immature tooth with a healthy pulp. It may be difficult to differentiate between this finding and a pathologic radiolucency resulting from a necrotic pulp. Comparison with the periapex of the contralateral tooth may be helpful. Unfortunately, it has not been possible to establish a close correlation between the results of these individual tests and the histological diagnosis (11 13) but it is hoped that by combining the results of the history, examination and diagnostic tests, an accurate clinical diagnosis of pulpal vitality can be made in most cases. When the pulp is deemed vital, apexogenesis techniques can be attempted. A necrotic pulp condemns the tooth to apexification.
LASER DOPPLER FLOWMETRY – A POTENTIAL AID TO VITALITY TESTING AND PULP REVASCULARIZATION A particularly difficult situation occurs following damage to the young permanent tooth with an open apex. Revascularization is a possibility and is highly desirable not only to maintain an infection free pulp space, but to allow the tooth to continue to develop and strenghthen. On the other hand if pulp vitality is lost, the resultant infection will initiate an inflammatory resorption which can result in tooth loss in an alarmingly short time. Unfortunately
current
sensitivity
tests
are
poor
indicators
of
revascularizaiton, with the result that many pulps which were successfully
undergoing revascularization are removed unnecessarily due to the seriousness of allowing a pulp to become necrotic with subsequent infection and inflammatory resorption Revascularization if highly desirable for a number of reasons. Maintenance of vitality ensures a bacteria free pulp space and thus inflammatory resorption is avoided. The expense and danger of procedural accidents of endodontic therapy are also avoided. In addition, because tooth development continues, the possibility of post treatment fracture due to thin, weakened dentinal walls is reduced. In traumatized young permanent teeth, an objective, reliable test of the blood supply to the pulp, would enable the clinician to accurately differentiate between a pulp which is regaining its vitality and one which is becoming necrotic. Early treatment decisions could then be made, herby reducing tooth mortality. Laser Doppler flowmetry is an objective test of the presence of moving red blood cells within a tissue, which has been reported to be effective in the detection of tooth pulp vitality as well. Laser Doppler flowmeters, have several advantages to clinical use for pulp resting in dentistry. They are objective, directly measure blood flow and do not rely on sensory nerve response. Furthermore the procedure is completely painless and should be reliable in teeth with immature apices.
50. Mesaros SV, Trope M, In a case presented by Mesaros SV, Trope M the laser Doppler Flow meter was utilized, and found to be more effective than CO2, ice in assessing the occurrence of revascularization. An eight year old child severely luxated both maxillary central incisors. While only one of the incisors was weakly responsive to CO 2 ice at 76 days after
replantation,
the
laser
Doppler
flowmeter
indicated
that
revascularization was occurring in both teeth at a much earlier time. Because of the laser Doppler readings endodontic treatment was not initiated and the teeth developed normally. On average, the blood flow signal was 42.7% lower from teeth with necrotic pulps compared to vital pulp measurements.
APEXOGENESIS Apexogenesis involves removal of the inflamed pulp and the placement of calcium hydroxide on the remaining healthy pulp tissue. Traditionally this has implied removal of the coronal portion of the pulp. However, the depth to which the tissue is removed should be determined by clinical judgment. Only the inflamed tissue should be removed, but the difficulty in assessing the level of inflammation is widely acknowledged. However a number of investigators have demonstrated that, following mechanical exposures of the pulp that were left untreated for up to 168 h, inflammation was limited to the coronal 2-3 mm of the pulp (14). This has led to the development of the socalled Cvek or shallow pulpotomy in which only the most superficial pulp is removed. The goals of apexogenesis, as stated by Webber (15) are as follows: Sustaining a viable Hertwig's sheath, thus allowing continued development of root length for a more favorable crown-to-root ratio. Maintaining pulpal vitality, thus allowing the remaining odontoblasts to lay down dentine, producing a thicker root and decreasing the chance of root fracture. Promoting root end closure, thus creating a natural apical constriction for root canal filling. Generating a dentinal bridge at the site of the pulpotomy. While the bridging is not essential for the success of the procedure, it does suggest that the pulp has maintained its vitality.
MATUROGENESIS Although vital pulp capping and pulpotomy procedures of cariously exposed pulps in mature teeth remain controversial, it is university accepted that vital pulp therapy is the treatment of choice for immature teeth (incompletely developed apices). Whenever a pulp exposure occurs in an immature tooth, it is appropriate to use a clinical technique that preserves as much vital pulp as possible. This step enables continued physiologic dentin deposition and complete root development. We would like maturogenesis to become the accepted term to use when dealing with the treatment of immature teeth with vital pulps. Matruogenesis shows a concern not only for a wide open apex (apexogenesis) but also for roots having very thin and weak walls. These teeth should be treated with total root development as the main concern so that sufficient root strength can be attained to protect against subsequent root fracture. Article 34 Rebeca Weisleder and Claudia R. Benitez
The total time for achievement of the goals of the apexogenesis ranges between 1 and 2 years depending on the degree of tooth development at the time of the procedure. The patient should be recalled at 3-monthly intervals in order to determine the vitality of the pulp and the extent of apical maturation. If it is determined that the pulp has become irreversibly inflamed or necrotic, or if internal resorption is evident, the pulp should be extirpated and apexification therapy initiated.
METHODS FOR THE TREATMENT OF TEETH WITH AN INCOMPLETELY
FORMED
APEX
(OPEN
APEX)
AND
A
NECROTIC PULP 55. Treatment of injured teeth with necrotic pulps and incomplete apical development. Enrique Basrani According to Enrique Basrani , In teeth that have not completed apical development, that anatomy of the root canals walls may appear as follows. The apical walls are convergent The apical walls are parallel The apical walls are divergent When an apical stop is present in teeth with convergent apical walls the root canal is obturated by standard techniques. In teeth with parallel apical walls, the obturation techniques are called single cone and inverted cone In teeth with divergent apical walls, the technique uses an alkaline paste
According to Morse et al there are at least 5 methods of treating a tooth that has a necrotic pulp and an open apex. These methods are 1. A customized cone (Blunt end, rolled cone) filling the root canal with the large (blunt) end of a gutta percha cone or customized gutta percha cones with a sealer. 2. A short fill technique Filling the root canal well short of the apex (before the walls have diverged) with gutta percha and sealer or zinc oxide eugenol (ZOE) alone. 3. Periapical surgery (with or without a retro grade seal) Filling the root canal with gutta percha and sealer as well as possible and then performing periapical surgery with or without a reverse seal. 4. Apexification (Apical closure induction) Inducing apical closure by the formation of an apical stop [Calcium hydroxide, Ca(OH)2) is generally used)] against which a permanent root canal filling can subsequently be inserted. 5. One visit apexification placing a biologically acceptable substance in the apical portion of the root canal (Dentinal chips or tricalcium phosphate have been used) thus forming an apical barrier. This is followed by filling the root canal with gutta percha and sealer.
I. CUSTOMIZED CONE (BLUNT END OR ROLLED CONE) The immature canal is complicated by a gaping foramen. The apical opening is either i.
A non constructive terminus of a tubular canal (or)
ii.
A flaring foramen of a “Blunderbuss” shape.
If apexification fails or is inappropriate special methods must be used to obturate the canals without benefit of the constrictive foramen serving as a confining matrix against which to condense. Complete obturation requires the use of the largest gutta percha points blunted or customized (“tailor made”) to fit the irregular apical stop or barrier. 1. blunted points 2. inverted point technique 3. apical impression technique -by heat -by chemical 4. rolled cone -by heat -by chemical 5. thermoplasticized gutta percha Cold lateral compaction is not the technique of choice because 1.
The resistance of the canal walls for lateral pressure is reduced in immature teeth.
2.
Greater bulk of gutta percha requires an even greater force to deform.
3.
Gutta percha in seldom used sizes, can become brittle in storage and requires even greater pressure to deform.
Warm gutta percha techniques are best suited for filling immature canals and apices.
Tubular canals SELECTION OR PREPARATION OF TRIAL POINT The large tubular canal with little constriction at the foramen may best be filled with 1. Blunted Points: “Coarse” primary gutta percha cone that has been blunted by cutting off the tip. 2. Tailor - made gutta percha roll/custom cone. If the tubular canal is so large that the largest gutta percha point is still loose in the canal; a tailor made point must be used as ‘a primary point’. This point may be prepared by i. Heating - a number of heated, coarse, gutta percha points are arranged butt to tip, butt to tip on sterile glass slab. - Points are rolled with spatula into rod shaped mass. - By repeated heating and rolling, the roll of gutta percha is formed to approximate size of canal to be filled.No voids should exist in mass.
- The roll must be chilled with a spray of ethyl chloride or ice water to stiffen the gutta percha before it is filled in the canal. - If it goes to full depth easily but is too loose, more gutta percha must be added. - If it is only slightly too large, the outer surface of the gutta percha can be softened by flash heating over the flame (or) flash dipping the point in chloroform, eucalyptol, or halothane and the roll forced to proper position. By this method, an internal impression of the canal is secured - It is dipped in alcohol to stop the action of this solvent. Some shrinkage may alter the final impression and any compaction before the solvent has evaporated will permit the point to continue to flow under pressure. Development of custom cone (From cohen) - Two
or
more
cones
(either
standardized,
non
standardized, or a combination of the two) are chosen, depending on the shape of the canal. - The cones are softened with a light amount of heat until they become tacky and adhere to each other. - The cones are rolled and fused together between two glass slabs to the desired shape and taper. Angle of the top slab to the bottom slab determines the shape or taper of the canal, whereas the amount of pressure on
the slab determines the thickness of the cone at any point along its length. - Finally, the apical portion of the cone is softened, either with chemicals or heat, and adapted to the irregular shape of the apical portion of the canal. - Subsequent canal obturation can be with either lateral or vertical compaction.
ii. Chemically plasticized cold gutta percha A modification of the lateral compaction technique involves the use of a solvent to soften the primary gutta percha point in an effort to ensure that it will better conform to the aberrations in apical canal anatomy. This is a variation of a very old obturation method, the so called Callahan – Johnston technique. Callahan – Johnston technique This technique was first promulgated by Callahan in July of 1911. It used a mixture of chloroform, rosin, and gutta percha. The problem with the original technique centred around the use of too much of the chloroform solvent, which resulted in a 24% decrease in volume in vitro. The chloroform had evaporated leaving powdered guttta percha. (In addition to Callahan Johnston technique) from Weine, 6 th Edition. Partially dissolved gutta percha Callahan and Johnston suggested techniques using solvents with gutta percha to fill canals. The solvents were chloroform or oil of eucalyptol, which were placed into the canal with a syringe, and then cones of gutta percha were plunged into the solvent. From the evaporation of the solvent and dissolving of the soluble gutta percha, a thick creamy mass developed, which solidified to form a canal filling. Disadvantages
Subsequent studies revealed that a considerable amount of contraction developed in the filling after solidification. This dimensional change amounted to as much as 7% which could possibly destroy the apical seal. Other studies indicated that the solvents used were more irritating to periapical tissues than were most root canal sealers. For these reasons, the techniques were only rarely employed. Today’s use of solvents is quite modest in comparison with the older methods. 3 b) CHEMICAL SOFTENING AND ADAPTATION Chloroform dip technique Usually on the tip of the point is dipped in the solvent and then only for 1 second. In this technique the primary point is blunted and fitted 2.0mm short of the working length. It is then dipped in the solvent for 1 and set aside while sealer is placed in the canal. This allows the solvent to partially evaporate. Too much solvent, as with a two- or three- dip method, will materially increase leakage. Not only does the gutta percha volume shrink as the solvent evaporates in the canal, the sealer leaks as well, probably because of solvent dissolution. To begin the obturation by lateral compaction, one must immediately position the customized master point to its full measured length and then spread it aside to allow the softened gutta percha to flow. The spreader is rotated out and is followed by additional points, spreader and points. Because 2.0 mm of the master tip have been solvent softened, it will flow to place to produce “smooth, homogeneous, well condensed gutta percha fills
closely adapted to the internal canal configurations in the apical third, including the filling of lateral canals, fins and irregularities. According to a study by Metzger et al (1988) the point should be positioned and spread within 15 seconds of being softened, otherwise, it will have lost its plasticity. After 30 seconds of air drying, it changes shape. This simple chloroform dip shrank only 1.4%. The principal solvent used in this technique is chloroform. At one time there was concern that it was carcinogenic, but it has recently been cleared for clinical sue in dentistry by the FDA, occupation safety and health administration, and ADA. In any event, other solvents such as eucalyptol, halothane, xylene, and rectified turpentine have been evaluated as substitutes for chloroform. Customizing master points with solvents improves the seal of gutta-percha. From cohen The apical 2 to 3 mm of a slightly oversized master cone is placed in a solvent (eg chloroform, methylchloroform, rectified white turpentine, eucalyptol) (Eucalyptus oil). For about 3 to 5 seconds, removed and placed into the canal until the working length is achieved with a good apical fit. The position of the cone in the canal is marked with regard to depth of placement and orientation to curves. This can be done by scoring the cone with either a cotton forceps or an explorer. The cone is fit into the canal when an irrigant is present to prevent the adherence of the softened gutta percha to the canal walls and to moderate the action of the solvent. Once fit the cone is checked radiographically, removed and thoroughly irrigated with sterile water to eliminate any residual solvent. Alcohol can also be used to remove the
solvent and the master cone should be allowed to dry for 1 or 2 minutes before cementation and compaction. Main disadvantages 1. Dramatic shrinkage of the solvent softened material. 2. High incidence of overfilling. 3. Potential toxicity of these materials. 4. The apical foramen is generally wider than the root canal orifice. This would prevent proper condensation of the gutta percha, and proper preparation of the canal would weaken the tooth considerably. 5. Difficulty of assessing the point of root development radiographically because root formation in the buccolingual plane is less advanced than it is in the mesiodistal plane. Completely obturation of these canals requires a modification of the master gutta percha cone to better adapt to the irregularly formed apical matrix or barrier. This may be accomplished by 1. Blunted points 2. Inverse point technique 3. Apical adaptation technique/direct impression technique a. Heat softening of commercially available, large cones. b. Chemical softening of commercially available large cones. 4. The creation of a large custom cone - by heat - by chemicals
The details of each technique are as follows a. Heat softening and adaptation - Heater water is used to soften the apical portion of the master cone before it is placed in the canal. The cone is dipped into the water (100o to 120oF, 37.8o to 48.8oC) for 2 to 4. seconds to soften only the outer layers of the apical portion of the cone. - Flash heating over the flame - End point of the primary gutta percha cone is plasticized with a heated instrument. The root canal is dried with sterile absorbent papers and a gutta percha master cone is selected. The cone must have adequate ‘tug – back’ 0.5 mm short of the working length. The blade like end of a stainless steel Woodson instrument is then heated for 6-7 seconds in a salt or glass bead sterilizer (230 – 240oC) and the hot instrument is used to transfer the heat to the tip as well as the lateral surface of the apical 2-3mm of the gutta percha master cone. The contact time of the heated instrument on the gutta percha master cone is relatively quick (1-2 seconds). In cases where the size of gutta percha master cone is large 2-3 heating cycles may be needed to plasticize the tip of the cone adequately.
Customized Master Cone Development (from Weine) An imprint of the apical portion can be obtained by using a solvent, and a master cone can be developed. The suggested solvent is chloroform, preferred because it is more volatile than xylol or oil of eucalyptol, and no solvent adhering to the cone is desired during condensation. Cotton pliers with a lock or a hemostat are also mandatory in this technique because the cone must be inserted into the canal several times in exactly the same spatial relationship. By holding the cone with a locking device and using some portion of the tooth usually a cusp tip or incisal edge as a landmark, the dentist can reinsert the cone in the same path as frequently as necessary to obtain a satisfactory imprint. A master cone that has correct length and width is seized with pliers at the predetermined length and dipped into a dappen dish containing chloroform. Only the apical 5mm of the cone is dipped, for 1 to 2 seconds. The softened cone is then placed into the prepared canal with slight apical pressure, held for a few seconds, and withdrawn. This procedure should be repeated at least one more time or until a satisfactory imprint is obtained. If a correct preparation has been made, the cone will assume a pointed tip, and striations will be noted along the lateral portion, recapitulating the canal interior. It is advisable to have the canal filled with irrigant while the imprint is taken. Either NaOCl or anaesthetic solution is very good for this purpose. Otherwise, some of the softened gutta percha might stick to the dried dentin walls and cause distortion of the cone. When the cone has assumed what appears to be an accurate shape, a radiograph is taken to verify the correctness of the apical position. During
the time that the radiograph is being developed, the cone should be removed from the canal and retained in the locking pliers, so that it may be correctly reinserted during filling. At this time, any residual solvent will volatilize and the cone will regain its original rigidity. If the cone is found to be too long, the dentist usually can easily tell at which point it passes through the apical foramen. A constriction in the cone is seen, with the area past this constriction being irregular and frequently having residual blood. The error in working length is calculated and corrected to the site of the constriction. The apical portion of the canal is enlarged by one or two more sizes, and another customized cone obtained. Once its correct length is verified the cone is used in one of the acceptable cementing techniques. Taking an imprint for a customized cone a. Chloroform is poured into a dappen dish. A master cone with correct length and width is grasped with the locking pliers at the working length and dipped into the chloroform for a few seconds. b. While being held with the cotton pliers, the cone (tip softened by the chloroform) is inserted into the canal with slight apical pressure. The canal has been irrigated with NaOcl for lubrication. c. The cone assumes the shape of the interior of the canal with a pointed tip and lateral striations. d. If the cone passes through the apex into periapical tissue, residual blood is seen near the tip. The true apical foramen is indicated by the constriction prior to the indication of bleeding. To correct this problem, measure the distance to the true apex, enlarge several sizes, and then take a new custom cone.
2. Inverted point technique The particular type of canal for which this method of filing is most applicable is the tubular canal found in the tooth that suffered early depth of the pulp, or one that has been ‘resurrected’ by apexification as cited above. As a primary point, a “coarse” gutta percha cone is selected and the serrated butt end of the point is carefully removed with a scalpel. The point is inverted and tried in the canal, that is, it should visibly go to full depth, but stop dead just short of the apex. It should exhibit “Tugback” when an attempt is made to remove it. Finally it should appear in the radiograph to be in optimum position to obliterate the foramen area of the canal. If the inverted point is thought to fill correctly, the requirements of a primary point, the canal is liberally coated with cement and the cement coated is slowly pushed to full position. This point may act as a plunger because of the shape of the canal and the tight fit of the point. If the point is placed slowly, relatively little cement will be forced into the peri radicular tissue. When the primary inverted point is in place, additional gutta percha points should be carefully added by lateral condensation with the spreader. It is most important at this time to mark the length of the tooth on the spreader. So the instrument will not penetrate into the peri radicular tissue. The spreader is used repeatedly followed by auxiliary gutta percha points until the canal is totally obliterated. The common error in this technique is an outgrowth of fear of overfilling. Insufficient pressure is applied during lateral condensations, resulting in poorly condensed filling. This in turn allows subsequent leakage and uncrates failure.
Root canal obturation for large canal using inverted, blunted gutta percha cone. a. Inverted cone should adequately fill apical canal space. Spreader should reach to within 1.0mm of foramen. b. Total obturation with additional points. Excess gutta percha and sealer are removed from crown filled by vertical compaction with large plugger.
5. Special method of obturating tubular canals with closed apex Simpson T and Natkin E. (1972) Simpson and Nathin have suggested a specialized filling technique for those teeth with tubular canals but closed apices. These are the roots that were originally blunderbuss in shape, but have been induced to complete their growth by the introduction into the root canal of a biologically active chemical such as calcium hydroxide. The canal is initially filled with a warmed and softened a tailor made gutta percha roll cemented to place and several at the canal orifice with a hot spoon excavator. Using a heavy plugger, the gutta percha is forced to apex and compacted to place. Pressure with the plugger will leave a void in the center of the mass when the plugger is removed with a twisting motion. It may be necessary to hold the gutta percha in place with an explorer when removing the plugger. The plugger is dipped in oxyphosphate of zinc powder to prevent sticking and then used to collapse the gutta percha into the space created by the initial plugging. If the gutta percha begins to set, the
plugger is heated to better compact the filling. With heavy vertical pressure, the entire canal is obturated and the excess gutta percha seared off at the gingival level. a.
Large cold plugger is used to force heat softened tailor made gutta – percha to apex.
b.
Twisting removal of plugger leaves a central void
c.
Plugger is used to collapse gutta percha into void.
d.
Heated plugger may be used to further compact filling.
e.
Final obturation by adding sections of gutta percha with vertical compression.
A. Cross section of tubular canal in “young” tooth, ovoid in shape. B. Blunted, “coarse” gutta-percha cone or tailor made cone used as primary point, followed by spreading and additional points to totally obturate ovoid space. Final vertical compaction with large plugger.
Root canal obturation for large canal using inverted blunted gutta-percha cone. A. inverted cone should adequately fill apical canal space. Spreader should reach to within 1.0 mm of foramen B. total obturation with additional points. Excess gutta-percha and sealer are removed from crown filled by vertical compaction with large plugger.
Special method of obturating tubular canals with closed apex. By Simpson and Natkin A. large cold plugger is used to force heat softened tailor made gutta percha to the apex B. twisting removal of plugger leaves central void C. plugger is used to collapse gutta percha into void D. heated plugger may be used to further compact filling E. final obturation with addition sections of gutta percha with vertical compaction
II. SHORT FILL TECHNIQUE Moodnick proposed removal of the bulk of the necrotic tissue and filling the root canal short of the apex with gutta percha. He advocated used of Diaket (Premier Dental Products), a compound of beta ketones and zinc oxide, in place of gutta percha to enhance healing. However with an incomplete obturation microbes can be left remaining within the apical part of the root canal system and healing may not take place or periapical breakdown may occur later.
III. ENDODONTIC SURGERY ON IMMATURE TEETH The idea of surgical manipulation and repair of an incisor tooth with open apex is not a new concept, but one that has been around for quite some time. Frank and Leubke during the 1960’s presented cases involving necrotic incisors with immature apices and discussed their surgical intervention and repair with amalgam. However, this treatment alternative never become popular or accepted. Calcium hydroxide apexification became the standard by which to treat these cases. Retrospectively, one reason for the dismissal of such a practical one appointment treatment was poor patient selection. But most importantly, amalgam that was used as an apical repair material in these specific cases was, and is, inadequate. (EARLIER) REASONS FOR NOT ADVOCATING SURGICAL APPRAOCH Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. 1. Relative to the already shortened roots, further reduction during the apicectomy could result in an inadequate crown to root ratio. 2. General anaesthesia is frequently required for the apicectomy in these young patients and surgery could be both physically and psychologically traumatic to the young patient. 3. The young patient is not apt to be cooperative. 4. Surgery would remove the root sheath and prevent the possibility of a further root development. 5. The apical walls of an immature root canal are thin due to lack of dentine apposition and could shatter when touched by a rotating bur.
6. The thin walls, are prone to fracture during the preparation of an undercut for the apical amalgam seal 7. The thin walls would make condensation of a retrograde material like amalgam difficult. This can result in an inadequate seal. 8. The peri apical tissue may not adapt to the wide and irregular surface of the amalgam. 9. The delayed expansion of amalgam and its effects in the thin root canal walls of these immature incisors. 10.The well recognized phenomenon of argyrophilic gingival tattooing was a common unacceptable clinical sequela of amalgam apical repair of teeth with immature apices.
Currently with the decline in use of amalgam as a retrograde material and with the availability of newer retrograde filling materials, surgical treatment of these teeth in a one step apexification model is being considered as a possible alternative.
Indication - Initially, when large chronic apical lesions are present on an immature tooth at an evolutionary stage, which no longer corresponds to the patients age. - Secondly, after failure of apexification.
Advantages - Rapidity of treatment by fewer appointments than in the treatment by apexification. - Reduction of the risk of fractures by reinforcing dentin walls with dentin bonding materials like GIC. - Immediate suppression of periapical lesions - An efficient, reliable apical barrier, ensuring better and easier 3 dimensional canal filling. Possible causes of unsuccessful treatment. - Hidden root failure - Inefficient leakage resistance of the retrograde closure resulting from inappropriate handling of GIC. - Inefficient curing of the periapical lesion resulting in the appearance of further lesion. Not recommended - For patients whose general health is poor. - For children not inclined to cooperate. - When there is insufficient bone substance for the tooth needing treatment.
MATERIALS PROPOSED FOR USE IN ENDODONTIC SURGERY 1. Super ethoxy benzoic acid. 2. Mineral Trioxide Aggregate 3. Autopolymerizable glass ionomer cement.
CHARACTERISTICS
OF
RETRO-FILLING
MATERIAL
FOR
ENDODONTIC SURGERY 1. Autopolymerizable glass ionomer cement - Chemical adherence to the dentine resulting in good sealing ability. - Efficient leakage resistance. - Biocompatibility of the material with the apical tissues. - Little tendency to dissolves in tissue fluids after setting. - Ease of handling and of insertion because of its condensable and auto polymerizable quantities - Ease with which it can be polished resulting in a better link with the peri apical tissues - Radio-opacity. - Good mechanical properties - Low cost. 2. Super ethoxy Benzoic Acid (Super-EBA) cement - The material is dimensionally stable and eliminates the risk of root fracture by delayed expansion. - Has high compressive and tensional strength
- Neutral pH. - Low solubility - Is biocompatible with the periapical tissues - No tendency for tattooing the gingiva. - (Some investigators suggest) sound adhesion to dentin) - Improved leakage resistance with time. - Exhibits minimal cyto toxicity Disadvantages - Hard to handle by the beginner - Tacky and difficult to keep in place if not mixed to an adequate consistency
Advantages of surgical alternative i
Cases are always complete
ii.
Multiple appointments and long follow ups are not necessary
iii.
Inter appointment fracture are not a problem.
iv.
Some of these immature apices are associated with large apical lesions usually of necrotic pulpal etiology. But surgical apexification permits the complete removal of the lesion with its subsequent submission to an oral pathologists for histological interpretation.
Limitations of surgical techniques 1.
Should note be used in short rooted teeth with extreme apical immaturity. The ostectomy and apical preparation, in these cases, would compromise alveolar bone support and stability.
2.
In young children who are dentally under developed and in whom such a surgical procedure might lacerate an adjacent developing tooth but, another vital immature root end, or hinder alveolar bone development.
3.
Medically compromised young adults or school children.
4.
Patients who for one reason or another cannot be selected.
SEALERS TO BE USED Ketac Endo (ESPE Ginbh, Seefeld, Germany) - Glass ionomer cement endodontic sealer. - Introduced by Ray HL, Seltzer S in 1991. - Biocompatible in bone. - Exhibits modified working and setting times - No shrinkage upon setting. - Superior adaptation to the canal walls. - Radio opacity - Dentinal bonding property makes root more resistant to fracture. - Earlier only a single GP cone was advocated when using Ketac – Endo. This also prevents vertical root treatment associated with gutta percha condensation techniques. - Highly resistant to resorption by tissue fluids - Technically less demanding of effecting apical seals. - Has an inherent, potential for providing for providing a more stable apical seal. - ZnO component of GP cones may chelate with the polyacrylic acid and form salt bridges. JOE, Vol.21, July No. 7, 1995 (Shimon Fried man) In a clinical study using Ketac Endo concluded. - Teeth with single canals showed a higher success rate than teeth with multiple canals.
- Failure rate in teeth with infected canals and resulting periapical lesions was almost 3 times higher than in teeth without lesion. - Treatment results significantly poorer in symptomatic teeth. - Treatment in single session resulted in a 10% higher success rate than multiple session treatment. - Teeth filled with a single cone or laterally condensed GP comparable results. - Extruded KE is not resorbed. It becomes an implant in the peri apical tissues allowing bone growth in its immediate proximity without a fibrous tissue interface. It does not stimulate as osteoclastic response. - The type of restoration and the presence /absence of a post did not significantly affect the success rate (KE may have sufficiently sealed the canal even after post placement and reinforced the roots against treatment) JOE : Vol 23 No. 4 April 1997 – - Absence of chemical bonding to cones. - GP surface altered – by etching effect - More of a mechanical /physical phenomenon
IV. APEXIFICATION Reasons for introduction of apexification In the past, techniques for management of the open apex in non-vital teeth were confined to custom fitting the filling material (16, 17), paste fills (18) and apical surgery (19). A number of authors (16, 17) have described the use of custom fitted gutta-percha cones, but this is not advisable as the apical portion of the root is frequently wider than the coronal portion, making proper condensation of the gutta-percha impossible. Sufficient widening of the coronal segment to make its diameter greater than that of the apical portion would significantly weaken the root and increase the risk of fracture. The disadvantages of surgical intervention include the difficulty of obtaining the necessary apical seal in the young pulpless tooth with its thin, fragile, irregular walls at the root apex. These walls may shatter during preparation of the retrocavity or condensation of the filling material. The wide foramen results in a large volume of filling material and a compromised seal. Apicoectomy further reduces the root length resulting in a very unfavorable crown root ratio. The limited success enjoyed by these procedures resulted in significant interest in the phenomenon of continued apical development or establishment of an apical barrier, first proposed in the 1960s (20, 21). DIFFERENT METHODS OF APEXIFICATION 1. Removal of infected necrotic pulp tissue Moller et al. (23) have shown that infected necrotic pulp tissue induces strong inflammatory reactions in the periapical tissues. Therefore removal of the infected pulp tissue should create an environment conducive to apical
closure without use of a medication. McCormick et al. (24) have hypothesized that debridement of the root canal and removal of the necrotic pulp tissue and microorganisms along with a decrease in pulp space are the critical factors in apexification. A number of authors (25-28)have described apical closure without the use of a medicament. Some believe that instrumentation may in fact hamper root development and that preparation of these canals should be done cautiously, if at all (29). Cooke and Robotham (30) hypothesize that the remnants of Hertwig's epithelial root sheath, under favorable conditions, may organize the apical mesodermal tissue into root components. They advise avoidance of trauma to the tissue around the apex. This theory is supported by Vojinovic (31) and Dylewski (32).
2. Use of antiseptic or antibiotic pastes Much of the early work in the area of induced apical closure focused on the use of antiseptic and antibiotic pastes. A number of investigators (33, 34) demonstrated apical closure using an antiseptic paste as a temporary filling material following root canal debridement and Ball (35) successfully reproduced these results using an antibiotic paste. conditions for conventional root canal filling. Rule and Winter used a polyantibiotic paste to close the apex, and in some cases, described continued root development.
3. Induction of a blood clot in the peri radicular tissues
Many techniques have been suggested for induction of apical closure in pulpless teeth to produce more favorable conventional root canal filling. Most of these techniques involve removal of the necrotic tissue followed by debridement of the canal and placement of a medicament. However, it has not been conclusively demonstrated that a medicament is necessary for induction of apical barrier formation. Nygaard-Ostby hypothesized that laceration of the periapical tissues until bleeding occurred might produce new vital vascularized tissue in the canal. He suggested that this treatment 'may result in further development of the apex' (22). Ham et al 1972 also reported closure of the end of the root, by ‘induced blood clot’. The periapical tissues were deliberately probed with a file until bleeding occurred. Closure was achieved, but not as often as with calcium hydroxide. Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. It is accepted that in luxated or avulsed teeth with open apices, revascularization is a possibility. In fact, under ideal conditions and with chemical decontamination of the root surface, it is almost predictable. The explanation for this positive outcome is that although the pulp is devitalized after avulsion, it will stay free of bacteria for some time. The necrotic but sterile pulp will act as a matrix into which new tissue can grow. Because in traumatized teeth the crown is usually intact, it will take bacteria a long time to advance into the pulp space. If in this time, the new vital tissue fills the canal space, the ingress of bacteria will be stopped. Regeneration of a necrotic pulp is considered possible only after avulsion of an immature permanent tooth. The advantages of pulp revascularization lie
in the possibility of further root development and reinforcement of dentinal walls by deposition of hard tissue, thus strengthing the root against fracture. After reimplantation of an avulsed immature tooth, a unique set of circumstances exists that allows regeneration to take place. The young tooth has an open apex and is short. Which allows new tissue to grow into the pulp space relatively quickly. The pulp is necrotic but usually not infected, so it will act as a matrix into which the tissue can grow. It has been experimentally shown that the apical part of a pulp may remain vital and, after reimplantation, may proliferate coronally, replacing the necrotized portion of the pulp. In addition, the fact that, in most cases, the crown of the tooth is intact ensures that bacterial penetration into the pulp space through cracks and defects will be a slow process. Thus, the race between the new tissue and infection of the pulp space favors the new tissue. However, if it were possible to create a similar environment in a necrotic infected tooth with apical periodontitis as described for the avulsed tooth, regeneration should occur. Thus, if the canal was effectively disinfected, a matrix into which new tissue could grow was created, and the coronal access was effectively sealed, regeneration should occur as in an avulsed immature tooth.
Revascularization or regeneration of pulp tissue of necrotic immature tooth has been assumed to be impossible because it is extremely difficult to disinfect these canals. Mechanical instrumentation, an important step in root canal treatment, cannot be performed in these teeth because the walls are so thin. Thus, the disinfection relies solely on irrigants and intra canal medications. Traditionally, calcium hydroxide has been used as the
intracanal medication in apexfication procedures destroying tissues with the potential to differentiate into new pulp. Thus, with calcium hydroxide therapy, there is no expectation that the root canal walls will be thickened or strengthened. To the contrary, in a recent study, it was claimed that long term calcium hydroxide treatment will in fact weaken the tooth and predispose it to fracture Article 17 Francisco Banchs and Martin Trope 2004 Francisco Banchs and Martin Trope 2004 in a case report describes the treatment of an immature second lower right premolar with radiographic and clinical signs of apical periodontitis with the presence of a sinus tract. The canal was disinfected without mechanical instrumentation with the use of copious irrigation followed by a mixture of antibiotics. A blood clot was then produced to the level of the cementoenamel junction (CEJ), followed by a deep coronal restoration. With clinical and radiographic evidence of healing as early as 22 days, the large radiolucency had disappeared within 2 months, and at the 24months recall, it was obvious that the root walls were thick and the development of the root apical to the restoration was similar to that of the adjacent and contra lateral teeth. However with respect to the origin of the new pulp tissue, the authors could not be sure whether the vital tissue was pulp. However, based on the fact that the root continued to grow and that the walls of the root appeared to thicken in a conventional manner, it is likely that in the particular case, the tissue was in fact pulp with functioning odontoblasts. It was possible that some pulp tissue may have survived apically, even though most of the pulp was devitalized and heavily infected. Therefore, even though a large apical
lesion was present, it is probable that some vital pulp tissue and Hertwig’s epithelial root sheath remained. When the canal was disinfected and the inflammatory conditions reversed, these tissues could proliferate.
Apexification of wide open apex due to resection Article 35 C.M. Sedgley and R. Wagner 2003 This report describes a case where orthograde root canal treatment, retreatment and root apex resection were unsuccessful in the treatment of an infected mandibular right first molar. The periapical radiolucency eventually disappeared following second orthograde retreatment, and the tooth remained functional and asymptomatic 5years after aburation. Placement of intra canal calcium hydroxide for 12 months promoted root end closure and allowed obturation without extrusion of material into the periapical tissues.
NUMEROUS PROCEDURES AND MATERIALS HAVE BEEN RECOMMENDED TO INDUCE APEXIFICATION IN TEETH WITH IMMATURE
APICES
(LONG
TERM
APEXIFICATION
PROCEDURE). v.
No treatment
vi.
Infection control
vii.
Induction of a blood clot in the peri radicular tissues
viii. Antibiotics pastes. Polantibiotic paste by Winter ix.
Calcium hydroxide mixed with various materials
x.
BMP
xi.
Collagen calcium gel.
Artificial apical barrier (that allows immediate obturation of the canal). i.
MTA
ii.
Ca(OH)2 powder
iii.
Super EBA
iv.
Tricalcium phosphate
Calcium hydroxide
Although a variety of materials have been proposed for induction of apical barrier formation, calcium hydroxide has gained the widest acceptance. The use of calcium hydroxide was first introduced by Kaiser (20) in 1964 who proposed that this material mixed with camphorated parachlorophenol (CMCP) would induce the formation of a calcified barrier across the apex. This procedure was popularized by Frank (21) who emphasized the importance of reducing contamination within the root canal by instrumentation and medication and decreasing the canal space temporarily with a resorbable paste seal. Calcium hydroxide is used because it biologically stimulates the hand tissue, it is easy to prepare, any material beyond the apex is rapidly resorbed, it is easy to prepare, any material beyond the apex is rapidly resorbed,it has a high alkalinity. Calcium hydroxide is a finely ground white powder that has little or no solubility. It must be mixed with another substance to get it to the apical area of the root in concentrations that remain constant and that do not weaken its therapeutic properties. Generally the paste should contain as much calcium hydroxide as possible whatever vehicle is used. The hydroscopic pastes resorb more rapidly than do the oil base pastes. Calcium hydroxide is not easily seen on the radiograph when well condensed in the root canal, it may reach the radiopaque level of the dentin. The addition of an element of a higher molecular weight than calcium will permit better visualization of the paste. Iodoform, barium sulfate, or strontium may be added.
TYPES OF Ca(OH)2 PRODUCTS USED FOR APEXIFICATION - Prepared products - Commercially available products
Prepared products Alkaline pastes These are primarily composed of calcium hydroxide in paste form mixed with radio opaque substances and or medication Alkaline pastes do not harden. They are quickly resorbed in the periapical area and within the root canal. The speed of resorption iof indirect proportion to the diameter of the root canal and in inverse proportion to the density of the paste, its condensation, and the vehicle used. It may be used alone or combination with cones of solid filling material. Actually this type of filling materials is of a temporary nature, used only until apexification has been achieved . The alkaline paste most frequently used are the following. Maisto capurro paste Calcium hydroxide and iodoform in equal parts with distilled water or a 5% solution of methylcellulose
Small cylinders of calcium hydroxide and iodoform implanted I the subcutaneous tissue of the rat were resorbed at the same rate as those containing only calcium hydroxide (Maisto and Masruffo 1964) The calcium hydroxy is eliminated much more slowely than the iodofoorm but this is not seen in the radiograph because it appears to be eliminate at the same time as the iodoform. These pastes are rapidly resorbed in the periapical region.the average time or resorption is 1 to 10 days for each square millimeter of surface of over obturated materials as seen in the radiograph
Frank’s Paste : Calcium hydroxide and camphorated parachlorophenol The irritating properties of camphorated parachlorophenol hav ebeen dtudied by many authors whoa re of the opinion that this material procedures a severe inflammatory reaction on initial application.However Frank (1966) Steiner et al (1968) Van Hassel (1970) and Stevart (1975) used this material for the obturation of root canals of teeth with underdeveloped apices. The fact that this paste was well tolerated by the adjacent periapical tissue without any inflammation and with the deposition of osteodentin was demonstrated histologically by Dyleskly in 1971 Souza,in his experimental research in 1976,showed that the addition of camphorated parachlorophenol did not change the capacity of the calcium hydroxide to induce the formation of calcified tissue.It is possible that the camphored parachlorophenol is absored and checking it irritating action.
Frank stated that camphorated parachlorophenol is an oily substance that slows resoprtion of the paste and is an assurance that the paste will remain in the areas of application for a longer time. Calcium hydroxide and camphorated parachlorophenol (CMCP) A number of studies (32, 36, 37) have reported a high level of clinical success with the use of calcium hydroxide in combination with CMCP.
Leonardo’s paste Calclium hydroxide barium sulfate, resin and polythyleneglyol Leonardo called this paste, ”calcium hydroxide No.9” it is used 1. as a dressing between visits in cases of biopulpetomy 2. To protect the vital apical and pericapical tissues in the a\obturation of the root cananls. 3. As a temporary obturation inc ases of incomplete apexification to induce mineralization and allow formation of new cementum. Leonardo : calcium hydroxide
2 grams
Barium sulfate 1gram Rosin 0.05gms Polyethylene glycol 4000 1.75gms
Other combinations are 2. Calcium hydroxide and cresatin Klein and Levy (38) and others (39, 40) described successful induction of an apical barrier using calcium hydroxide and Cresatin (Premier Dental Products). Cresatin had been shown to have minimal inflammatory potential as a root canal medicament (41) and to be significantly less toxic than CMCP (42). 3. Calcium hydroxide and saline/sterile water/distilled water To further reduce the potential for cytotoxicity, the use of calcium hydroxide mixed with saline (43), sterile water (44, 45) or distilled water (46) has been investigated with similar clinical success. Obtuartion with a hygroscopic paste has its disadvantages for it does not slide easily along the entire length of the canal. On the contrary,the compact consistency and the low mobility of the paste gives the feel that the root canal has totally obturated when in reality the apical part of the canal is free of paste. For this reason, it is preferable that the vehicle for the calcium hydroxide be oily.
Commercially available products 1.Reogan Rapid Reogan Rapid contains calcium hydroxide, barium sulfate, calcium oxide, magnesium oxide, casein and distilled water
2.Pulpdent Heithersay (47, 48) and others (49, 50) have used calcium hydroxide in combination with methylcellulose (Pulpdent Corporation, Watertown, MA, USA). Pulpdent has the advantage of decreased solubility in tissue fluids and a firm physical consistency (51). Pulpdent (consists of only calcium hydroxide, methyl cellulose and barium sulfate 3.Calasept Ghose et al., achieved a high success rate of 96% using Calasept to treat teeth that had become non-vital following complicated crown fractures 4.Calcicur 5.Hypocal Article 29 Mackie IC, Hill FJ, Worthington HV: Because in 1989 it was found that Reogran Rapid was no longer going to be marketed in the United Kingdom Mackie IC, Hill FJ, Worthington HV, was decided to compare another readily available proprietary calcium hydroxide paste, Hypocal, with the remaining stock of Reeogan Rapid. Successful apical closure was achieved in all the teeth. However,the differences in the mean time to achieve apical closure were not statistically significant but they did show a trend in favour of shorter time and less visits for apical closure in teeth treated with Hypo-cal.
Ca(OH)2 APEXIFICATION PROCEDURE 1. Measurement of apical opening
2. Access cavity preparation I.C. Mackie, E.M. Bentley and H.V. Worthington recommends preparing an access cavity that was large enough to permit instrumentation of the walls of the wide pulp chamber and canal, but did not weaken the crown of the tooth excessively Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. 3. Establish a working length Because of the irregular shape of many incompletely formed teeth it may not be possible to make the length determination with the same degree of precision that is possible in fully formed teeth. According to Robert J Oswald Henry j Van Hassel since the canal walls in the apical region may be paper thin, there is probably some advantage to establishing working length approximately 2mm coronal to the most apical root edge. By working at this slightly coronal level, there is less likelihood that the thin apical root structure will be torn by files. By restricting filing to within the root canal there is also less likelihood that periapical tissue that may still have the potential to participate in further root development will be damaged, hence additional root structure may form apical to the level to which calcium hydroxide was placed. 54. Robert J Oswald Henry j Van Hassel
4. Instrument the canal Large sized files are recommended. Instrumentation in these instances could be thought of as planing of all walls of the canal without an attempt to increase the size of the canal. In particular it is difficult to adequately debride the labial and lingual portions of the canal, since, as noted above, the pulp chambers in the apical portion of these roots are frequently much wider labio-lingually than they are in a mesio distal dimension. According to Robert J Oswald Henry j Van Hassel in order to contact all surfaces of the canal, it is necessary to place a curvature on the file.
3. Methods to control infection in the canal According to Mackie IC, Hill FJ, Worthington HV if infection was present, as indicated by pus in the root canal, this was controlled with a polyantibiotic paste which was introduced using Lentulospiral root canal filler to fill the canal. The access cavity was sealed using a cotton wool pledget and zinc oxide eugenol cement. Where the infection was acute, the first dressings was changed after 48 hours, subsequent polyantibiotic paste dressings were replaced at weekly intervals until the infection was controlled, a maximum of three being required before beginning treatment with calcium hydroxide paste. Article 29
Mackie IC, Hill FJ, Worthington HV:
Article 36
I.C. Mackie, E.M. Bentley and H.V. Worthington.
4. Methods to introduce Ca(OH)2 pastes in the canal Webbers technique –using amalgam carrier and endodontic pluggers Messing gun technique by Krell & Madison Lentulospiral at very low speed Mc Spadden compactor Disposable syringe with a thick needle Reamers turned counter clockwise Leonardo’ssyringe
Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. The calcium hydroxide paste was introduced into the dry canal using the needle dispenser provided. This allowed the paste to be injected well into the root canal, with the needle being slowly withdrawn as the material was injected. A spiral root canal filler was then used to ensure that the paste filled the root canal to the full working length (ie 1 mm short of the radiographic apex). More calcium hydroxide was injected into the canal if necessary, and when the canal was completely full, a cotton wool pledget was used to compress the paste gently before sealing the access cavity with a zinc oxide/eugenol cement. 54. Robert J Oswald Henry j Van Hassel
Plugging the Ca(OH)2 pastes in the canal can be done by moving the paste into the apical canal with a long plugger that can be introduced to within 2 to 3 mm of working length without binding on any of the canal walls. Although pluggers work well, some operators prefer to tamp the paste in place with the butt ends of large sized paper points. A large dry cotton pellet is then placed over the canal office, and additional condensation with a large plugger is performed.
5. Timing of change of Ca(OH)2 dressing Controversy exists as to whether or how often the calcium hydroxide dressing should be changed. Chawla (71) suggests that that it suffices to place the paste only once and wait for radiographic evidence of barrier formation while Chosack et al. (72) found that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months. Proponents of a single application claim that the calcium hydroxide is only required to initiate the healing reaction and therefore repeated applications are not warranted. Article 36
I.C. Mackie, E.M. Bentley and H.V. Worthington.
Article 29 Mackie IC, Hill FJ, Worthington HV:
The first calcium hydroxide dressing was replaced after one month. Subsequent dressing were changed every 3 months until a calcific barrier formed at the apex A number of authors (73, 74) propose that the calcium hydroxide should be replaced only when symptoms develop or the material appears to have washed out of the canal when viewed radiographically. Abbot (75) points out that radiographs cannot be relied upon to determine the amount of calcium hydroxide remaining in the canal or to demonstrate whether or not the barrier is complete. He concludes that regular replacement of the dressing has a number of advantages. It allows clinical assessment of barrier formation and may increase the speed of bridge formation (). Abbot (75) suggests that the ideal time to replace a dressing depends on the stage of treatment and the size of the foramen opening. This must be assessed for each individual tooth at each stage of development. 54. Robert J Oswald Henry j Van Hassel As long as the patient remains asymptomatic the first scheduled recall should be at approximately 6 months. At that time a radiograph is taken, in addition to making a clinical evaluation of mobility palpation and percussion tenderness and the status of the temporary filling. The radiograph should be examined to determine 1. If any calcification has occurred in the apical region. 2. If paste can still be seen inn the root canal. It root end closure is occurring but is not complete, the paste can be seen in the canal, and the temporary filling is in act, the paste should not be disturbed. In the event that you cannot see signs of apical closure, the paste
is not evident in the canal, or the temporary filling is breaking down, the tooth should be reopened and the instrumentation procedures and calcium hydroxide placement should be repeated. Recall visits should be continued at 6 months intervals until there is good radiographic evidence that the root end has closed
6. Procedures to detect barrier formation Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. In the methodology used by Ghose et al., immediately following the placement of the calcium hydroxide paste, a radiograph was taken to ensure that the paste completely filled the canal and, if voids were present, the dressing was repeated. The patients were then recalled monthly and a periapical radiograph taken to check for barrier formation and whether the calcium hydroxide paste was being absorbed at the apex. Only when the paste was not evident in the canal, or if it had been partially absorbed, was the tooth redressed. Article 29
Mackie IC, Hill FJ, Worthington HV:
In these days when there is growing concern about the amount of radiation to which children are exposed, the technique described by Mackie IC, Hill FJ, Worthington HV keeps the number of radiographs taken to a minimum by checking for the formation of a barrier at the apex clinically rather than radiographically
A very precise procedure was used to detect barrier formation. First the calcium hydroxide paste, which was non setting, was washed out of the canal with a disposable syringe and needle. After drying the canal, a paper point was then used to check the apical end of the canal when the presence of a resistant “Stop” and the absence of haemorrhage, exudates or sensitivity indicated successful barrier formation. Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. The presence of a barrier was initially investigated by use of a thin paper point. A calcific barrier was felt was a definite hard tissue stop at the root apex. If a stop was located, a file was gently introduced to confirm that the barrier completely occluded the root apex.
54. Robert J Oswald Henry j Van Hassel When you have radiographic evidence of root end closure, the tooth should be isolated and reopened. The final test that the root end has in fact calcified is made with #25 file. Since in some cases the bridge will be incomplete regardless of the radiographic appearance. The files should be incomplete regardless of the radiographic appearance. The files should be used to probe the entire surface of the calcified bridge. If the clinical test demonstrate a “dead stop” in all areas, obturation with gutta percha can be performed. If on the other hand voids are found in the bridge, consideration should be given to replacing the calcium hydroxide paste for another 6 months or until the bridge is complete.
MECHANISM OF ACTION OF Ca(OH)2 TO INDUCE FORMATION OF A SOLID APICAL BARRIER
The continuous absorption/depletion of Ca(OH)2 paste from the root canal suggests that it is continuously used in the formation of the bridge. The mechanism by which Ca(OH)2 acts in the formation of the bridge is still not fully understood. Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba However, Holland described in vivo, a phenomenon when calcium carbonate crystals were produced by a reaction between the carbon di-oxide in the pulp tissues and the calcium of the capping materials. Alkaline pH and calcium ions might play a part either separately or synergistically. The calcium required for the apical bridge formation comes through the systemic route as demonstrated by Sciaky and Pisanty. Pisanty and Sciaky using radiolabled Ca(OH)2. As the calcium ions from the calcium hydroxide dressing do not come from the calcium hydroxide but from the bloodstream (52, 53) the mechanism of action of calcium hydroxide in induction of an apical barrier remains controversial. Some of the postulated mechanisms of the osteoconductive effects of Ca(OH)2 are as follows: 1. Presence of high calcium concentration increase the activity of calcium dependent pyrophosphatase Mitchell and Shankwalker (54) studied the osteogenic potential of calcium hydroxide when implanted into the connective tissue of rats. They concluded
that calcium hydroxide had a unique potential to induce formation of heterotopic bone in this situation. Of 11 other materials used in comparative studies, only plaster of Paris (calcium sulfate hemihydrate) and magnesium hydroxide demonstrated any osteogenic potential. Heithersay (47, 48, 51) has postulated that calcium hydroxide may act by increasing the calcium concentration at the precapillary sphincter, reducing the plasma flow. In addition, the calcium ion can affect the enzyme pyrophosphatase, which is involved in collagen synthesis. Stimulation of this enzyme can facilitate repair mechanisms.
2. Direct effect on the apical and periapical soft tissue Holland et al. (55) have demonstrated that the reaction of the periapical tissues to calcium hydroxide is similar to that of pulp tissue. Calcium hydroxide produces a multilayered necrosis with subjacent mineralization. Schroder and Granath (56) have postulated that the layer of firm necrosis generates a low-grade irritation of the underlying tissue sufficient to produce a matrix that mineralizes. Calcium is attracted to the area and mineralization of newly formed collagenous matrix is initiated from the calcified foci. Schroder and Granath showed that OH ions induced the development of a superficial necrotic layer acting as a surface to which the pulpal cells gets attached, leading to bridge formation. Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba
3. High pH, which may activate alkaline phosphatase activity It appears that the high pH of calcium hydroxide is an important factor in its ability to induce hard tissue formation. Javelet et al (57) compared the ability of calcium hydroxide (pH 11.8) and calcium chloride (pH 4.4) to induce formation of a hard tissue barrier in pulpless immature monkey teeth. Periapical repair and apical barrier formation occurred more readily in the presence of calcium hydroxide.
4. Antibacterial activity It has been demonstrated that apical barrier formation is more successful in the absence of microorganisms (58) and the antibacterial efficacy of calcium hydroxide has been established). The antimicrobial activity is related to the release of hydroxyl ions, which are highly oxidant and show extreme reactivity. These ions cause damage to the bacterial cytoplasmic membrane, protein denaturation and damage to bacterial DNA.
MECHANISM OF ACTION OF Ca(OH)2 BEYOND THE APEX IN CASES WITH PERIAPICAL LESIONS
How the calcium hydroxide resorbs Another aspect of calcium hydroxide that deserves comment is the resorption of this material from within the root canal. Several authors such as Sparagberg (1967) Tsushima(1970) Yamada (1970) and Holland (19770 advise that the resorption of calcium hydroxide is in keeping with the injury caused to the apical tissue by endodontic instruments or by excessive filling. Holand 91977) showed evidences in dogs teeth that,when pastes are grossly overfilled,tehya re resorbed at different levels within the root cannal This does not occur when the obturation is not overfilled. According to strindberg (1956) the elimination of the filling paste is facilitated by phagocytic action and or the dissolving of the filling material by the tissue fluids.
Phagocytes takes place at pH6.9 and the pH of calcium hydroxide is approximately 12.8The resorption would only be possible with the reduction of the pH by the dissolving of the material in the tissue fluids. Maisto and Erasquin (1965) were of the opinion that macrophages and polymorphonuclear leukoctes can take part in the resorpton of material within the root canal. Souza believed that calcium hydroxide can be resorbed until the apex is closed with calcified connective tissue, after the resorption will not be possible. 55. Enrique Basrani
NATURE
AND
SOURCE
OF
CELLS
PARTICIPATING
IN
APEXIFICATION PROCESS There has been considerable differences in opinion regarding the nature and source of cells participating in apexification process I.
Mesenchymal or pluripotent precursor cells in the periapical region
(Hertwig’s epithelial root sheath ) Nevins A J et al 1978. Herthersay G S 1970 Piekoff MD 1976 II. Cells of the dental sac which surround the apex (and retain their genetic code) Klein and Levy 1974. III. Hard tissue comes from 2 sources 1. Odontogenic activity of residual pulp cells. (Most prevalent and most productive). 2. Connective tissue – cells maybe mesenchymal or fibroblastic in origin (With the possibility that they have retained their predetermined genetic pattern to form cementoblasts). Torneck and Coworkers (1970, 1973) IV. Pluripotent cells located within bone tissue (and that these cells are not necessarily specific to the periapical region). V. Hertwig’s epithelial root sheath
Ohara PK, Torabinejad M
TYPES OF CANAL CLOSURE 1. 4 types by Frank (Frank A. L.) 2. Cathey’s apexification treatment 5th type of canal closure (Gerald M. Cathey) The apical development continues with the growth of the tooth. According to the studies done by Alfred Frank the types of maturation can be as follows. a. The apex keeps its blunderbuss form but is closed by a thin walled calcific bridge. b. The apex keeps its blunderbuss form and the bridge of calcified tissue is formed beneath it. c. Apical maturation is produced without the root canal changing its form d. The apex develops normally. 4 patterns of closure following apexification by Frank 1. Continued apical development with a definite though minimal, recession of the root canal. 2. Continued apical development without any change in the root canal space (dome apexification ) JOE : 1996. No.12. 3. Thin calcific bridge, formation at the apex without apical development. 4. Lack of apical development with a calcific bridge just coronal to the apex. 5th type of canal closure (Cathey’s apexification treatment)
5. Continued apical development with calcific bridge just coronal to apex. (When the apical pulp can be retained in a vital condition, the root end and canal usually with assume a relatively normal size and shape. However when the pulp is completely non vital, root end develops in a short plunted condition, where as canal remains rather wide when apexification procedures are employed).
Article 33 Howard S. Selden (2002) Although the radiographic shape of the apexification induced calcified “Cap�, is variable. The most frequently seen closure seems to be a horizontal bridge spanning the tips of the flared apex (type 3). Howard S. Selden (2002) demonstrated in an interesting case the rare occurrence of a type 1 closure pattern that morphologically resembled normal root end formation in a lower left cuspid of a 12 year old male using Ca(OH)2 paste which was changed only once every year for 2 years. The unexpected formation of a mature apex served to demonstrate its possibility, but not its predictability. Successful treatment occurred with only two applications of Ca(OH)2 paste spaced 1 year apart, where as the widely accepted protocol recommended changing the paste every 3 to 6 months.
The hard tissue barrier has been described by Ghose et al. (65) as a Cap bridge ingrown wedge
NATURE OF INDUCED APICAL DEPOSITIONS 1. Cementum 2. Bone 3. Osteocementum 4. Osteodentin 5. Cementoid
Ghose et al. (65) described the hard tissue barrier as composed of cementum, dentin, bone or 'osteodentin' (32). This osteodentin appears to be formed by connective tissue at the apices, in that Hertwig's epithelial sheath is not seen. Torneck et al. (66) reported that a bonelike material was deposited on the inner walls of the canal while Steiner and Van Hassel (67) demonstrated apical closure by formation of a calcific bridge that satisfied the usual histological criteria for identification as cementum. Study of the serial sections gave the impression that cementum formation proceeds from the periphery of the original apex towards the center in decreasing concentric circles. Scanning electron microscopy and histological analysis of the apical barrier (70) demonstrated that the outer surface of the bridge extended in a 'cap like' fashion over the root apex, displaying irregular topography with indentations and convexities throughout. The histological sections showed distinct layers. The outer layer appeared to be composed of a dense acellular cementum-like tissue. This surrounded a more central mix of irregular dense fibrocollagenous connective tissue containing foreign material with irregular fragments of highly mineralized calcifications.
CONSISTENCY OF NEW APICAL FORMATION Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba There are conflicting views regarding the structures of calcified bridge. According to one school of thought, the bridge is a solid structure, consisting predominantly of the cementoid tissue, while others are of the opinion that bridge is porous with loose connective tissue inclusions in between. In a clinical case by Tarun Walia / Harpinder Singh Chawla And Krishan Gauba it was seen that following apical closure, the sealer (ZnOE) used along with gutta percha for obturation had extruded beyond the bridge. The author s concluded that if the calcified bridge would have been a solid structure, the sealer could not have gone in the periapex. The bridge formed, therefore is a porous structure. Swiss cheese configuration (not solid) In spite of radiographic and clinical evidence of complete apical bridge formation, histological examination reveals that the barrier is porous (
55. Enrique Basrani IN many cases, there is a slight overfill with the sealer which confirms the histologic observation that the bridge of mineralized tissue is not complete. But in some instances shows a sieve like appearance on microscopic slides.
MEAN TIME FOR APICAL BARRIER FORMATION Studies vary in assessment of the time required for apical barrier formation in apexification using calcium hydroxide. In a review of ten studies, Sheehy and Roberts (79), reported an average length of time for apical barrier formation ranging from 5 to 20 months. Finucane and Kinirons (78) reviewed 44 non-vital immature incisors undergoing calcium hydroxide apexification and found that the mean time to barrier formation was 34.2 weeks (range 13-67 weeks).
FACTORS INFLUENCING TIME TAKEN FOR APICAL BARRIER FORMATION AND HEALING. 1. Apical width According to Finucane and Kinirons (78) a barrier formed more rapidly in cases with narrower initial apical width. Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba Size of the apical foramen at the start of treatment â&#x20AC;&#x201C; Teeth with apices < 2 mm in diameter have significantly shorter treatment times Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. Root apices that were 2 mm in diameter or less took a geometric mean of 6.2 months to close. This was in contrast to those more than 2 mm in diameter, which took 11.0 months to close, a significant increase. Since less calcific material would be needed to occlude a narrow apex as opposed to a wide apex, it would be expected that the former would require the shorter per for treatment. This was confirmed by the results of this study, but contrasts with those of Ghose et al., who failed to demonstrate a similar relationship.
2. Age According to Finucane and Kinirons (78) age may be inversely related to the time required for apical barrier formation. In one study patients who were
11 years or older had significantly shorter treatment times (76). Others, however, refute this finding (80, 81). Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba It was found that older children having narrow open apex had a shorter treatment time than the younger children (NS); The calcified bridge formed following apexification is a porous structure. Age â&#x20AC;&#x201C; May be inversely related to ABF time. Since less calcified material would be needed to occlude a narrow apex as compared to wide apex, it is understandable that the former would require shorter period for apexification. In the study conducted by Mackie, patients, who were 11 years and older had significantly shorter treatment times. In the present study also, the mean time required for ABF in younger age group (7 to 11 year) was 7.0 months, while for older age group (12 to 16 year), it was 5.0 months. Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. There was significant
differences in the time taken to achieve apical closure between the three age groups ; 6-8 years, 9-10 years and 11-15 years. Significant differences were also found between the times to achieve closure and the width of the apex. There were no significant differences between closure times for the sex of the patient, shape of the apex or the presence / absence of periapical radiolucency.
3. Infection / periapical radiolucency Cvek (73) has reported that infection and/or the presence of a periapical radiolucency at the start of treatment increases the time required for barrier formation but other studies indicate no relationship between pretreatment infection and periapical radiolucency and barrier formation time (65, 76, 80, 81). Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba teeth without periapical infection showed some amount of root growth and closing of apex that was faster than those with periapical infection (p<0.001). Infection â&#x20AC;&#x201C; Some studies have reported that presence of periapical radio lucency at the start of treatment, increases the barrier formation time, whereas others have not. In the present study, the former holders have not.
In the present study, the former holds true. In teeth without
periapical infection, the average time required for apical closure was 4.9 months, while whose with periapical radio lucency, the corresponding figure was 8.5 months. The presence of periapical infection also determines the number of dressings required for the apexification. Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington.
. It was also interesting to note that the presence of a periapical radiolucency did not affect the time taken for treatment. This is in agreement with Ghose et al., but in contrast to Cvek and Sundstrom.
4. Inter-appointment painful symptoms Kleier and Barr (80) found that in the presence of symptoms the time required for apical closure was extended by approximately 5 months to an average of 15.9 months. Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba Inter-appointment painful symptoms â&#x20AC;&#x201C; May delay time taken for apical healing.
5. Frequency of Ca(OH)2 dressings According to Finucane and Kinirons, the strongest predictor of rapid barrier formation was the rate of change of calcium hydroxide Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba
Frequency of Ca(OH)2 dressings â&#x20AC;&#x201C; there is no census on how frequently Ca(OH)2 should be changed to induce apical healing. In the present study calcium hydroxide paste was replaced, if it has resorbed in the apical one third of the root canal until apical barrier formation is complete 6. Evidence of external resorption 7. Type of injuries
8. Method of detection of apical barrier Article 29 Mackie IC, Hill FJ, Worthington HV: The mean times to achieve apical closure of 6.8 and 5.1 months
are
considerably less than those reported by Mackie et al of 10.3 months. The reason for this is probably a change in the method used to detect the barrier. Mackie et al used a fine file to check that the apical barrier completely occluded the apical foramen and if any small deficiency was detected the tooth was redressed for a further three month period. In this present study a paper point rather than a file was used and this may not have detected small deficiencies in the barrier. However, this change of method proved to be acceptable since none of the final root fillings appeared radiographically to have breached or broken the barrier
SUCCESS RATES In a review of 10 studies, Sheehy and Roberts (79) reported that the use of calcium hydroxide for apical barrier formation was successful in 74-100% of cases irrespective of the proprietary brand used. They do point out that follow-up is necessary and information regarding long-term outcomes is limited. Problems such as reinfection and cervical root fracture may occur.
Number 2 Tarun Walia / Harpinder Singh Chawla And Krishan Gauba A retrospective study on 15 non-vital immature incisor teeth was done using Ca(OH)2 Pulpdent paste. A success rate of 100 percent was achieved within one year. The formation of apical barrier in all the fifteen teeth proves the effectiveness of Pulpdent paste in apexification procedures. Majority of the studies has reported high success rate using different Ca(OH)2 pastes for apexification. Heithersay used Ca(OH)2 and methylcellulose in 21 teeth and achieved apical closure in 90 percent of the teeth in the time range of 14 to 75 months. Chawla treated 26 non-vital teeth using Reogen Rapid paste and the success rate was 100 percent with 35 percent teeth showing apical closure in twelve months and 65 percent teeth in six months Thater used Pulpdent paste in 34 teeth, but achieved a lower success rate of 74 percent as compared to 100 percent in our study. However, Kleier
achieved 100 per cent success rate as achieved in the present study using Pulpdent paste on 48 teeth within 1 to 30 months. Mackie used both Reogen Rapid and Hypocal on 19 teeth each for apical closure and achieved 100 percent success using both the brands with the mean time period of 6, 8 months for Reogen Rapid and 5.1 months for Hypocal respectively. Article 36 I.C. Mackie, E.M. Bentley and H.V. Worthington. Successful closure of the apex of the root was achieved in 108 of the 112 incisors, representing a 96% success rate. three of the four failures occurred in replanted teeth, while the other was displaced from its socket.
FACTORS INFLUENCING SUCCESS RATES 1. Type of trauma 2. Age 3. Presence of horizontal / vertical root fracture
INHERENT DISADVANTAGES OF CONVENTIONAL Ca(OH)2 APEXIFICATION 1. Patient Compliance More apexification cases are started than completed. Patients or parents lose interest in such a length to complete, multiple appointment procedure. 2. Fracture before completion of treatment Although crown and root fractures are an unpredictable happening, they do occur occasionally in these immature wide canal incisors with in root walls. 3. Referring dentists referring dentists generally do not like the idea of waiting for nearly 1 year to have the case back in their practice. 4. Inconvenience of multiple appointments in the young adult scenario In these cases, a discolored tooth is commonly the motivator. It is usually after initial diagnosis by their dentist that patients know about their apical immaturity and its relationship to the discoloration. However the multiple appointments entailed by the apexification procedure. Obscures the real chief complaint of this young adult group, which is improving esthetics quickly.
5. Precise prognostic assessment sometimes impossible An incisor with a hidden root fracture could be unwisely and wastefully treated by apexification before the true nature of the problem is noticed. This is an ever present possibility in immature teeth usually devitalized by trauma. 6. Patient management Behavioral problems in young patients are difficult to manage and sometimes exacerbated by multiple appointments. 7. Economics After tallying the cost for multiple appointments, plus the time taken off from the work in the case of an adult, it is evident that apexification is an expensive, time consuming proposition.
INHERENT DISADVANTAGES OF Ca(OH)2 apexification 1. Variability of treatment time. 2. Unpredictability of apical closure 3. Difficulty to patient follow up. 4. Delayed treatment.
MINERAL TRIOXIDE AGGREGATE Although calcium hydroxide has been the material of choice for apexification, a number of authors have worked with other materials. In the 1970s interest was expressed in the use of tricalcium phosphate for induction of apical barrier formation with some success (82, 83). Nevins et al. (84) reported favorable outcomes using collagen-calcium phosphate gel. In recent times interest has centered on the use of mineral trioxide aggregate (MTA) for apexification. This material was first introduced in 1993 and received Food and Drug Administration (FDA) approval in 1998. MTA is a powder consisting of fine hydrophilic particles of tricalcium silicate, tricalcium oxide and silicate oxide. It has low solubility and a radiopacity that is slightly greater than that of dentin (85). This material has demonstrated good sealability and biocompatibility (86, 87). MTA has a pH of 12.5 after setting which is similar to the pH of calcium hydroxide and it has been suggested that this may impart some antimicrobial properties (88). It has been used in both surgical and non-surgical applications including root end fillings (86, 87, 89), direct pulp caps (90), perforation repairs in roots (91) or furcations (92, 93) and apexification (94, 95). Shababhang et al. (94) compared the efficacy of osteogenic protein-1 and MTA with that of calcium hydroxide in the formation of hard tissue in immature roots of dogs. They concluded that MTA produced apical hard tissue formation with significantly greater consistency. The difference in the amount of hard tissue formed among the three test materials was not statistically significant.
BONE MORPHOGENIC PROTEINS Used to promote bone formation Osteogenic protein â&#x20AC;&#x201C; 1 (OP-1) Uses - To induce bone formation - Use as pulp capping agent. - Root end induction. - is believed to attract and recruit mononuclear phagocytes to ectopic sites of bone formation. - Stimulates proliferation of mesenchymal cells that subsequently differentiate into osteogenic lineages. - Purified BMP is highly soluble in vivo and hence for hard tissue formation, is used with carrier â&#x20AC;&#x201C; mostly collagen carrier (collagen matrix carrier resorbs slowly over a 3 week period when implanted in bone that allows gradual release of the BMP) (Rate of resorption may be slower when placed within confines of the root canal). - OP-1 induced an apical hard tissue formation with the same frequency as seen in calcium hydroxide, however in larger quantities (Similar to MTA)
While the objective of apexification is to stimulate apical barrier formation, in the belief that continued root formation cannot occur, there are a number of reports of continued apical development in spite of a necrotic pulp (109, 110). Yang et al. (111) reported a case in which apical barrier formation was accompanied by a separate disto-apically growing root. Histological evaluation revealed immature hard tissue mixed with calcium hydroxide, connective tissue and bone apically in the original root canal. In the separate newly formed part of the root, pulp tissue, odontoblasts, predentin, cementum and an apical foramen could be identified. Selden (112) also described a case in which the outcome morphologically closely resembled normal root formation. It has been suggested that for continued root development to occur the area of calcific scarring must not extend to Hertwig's root sheath or to the odontoblasts in the apical area (113).
V. ONE VISIT APEXIFICATION Induction of apical healing, regardless of the material used, takes at least 34 months and requires multiple appointments. Patient compliance with this regimen may be poor and many fail to return for scheduled visits. The temporary seal may fail resulting in reinfection and prolongation or failure of treatment. The importance of the coronal seal in preventing endodontic failure is well established (). For these reasons one-visit apexification has been suggested. Morse et al. (99) define one-visit apexification as the nonsurgical condensation of a biocompatible material into the apical end of the root canal. The rationale is to establish an apical stop that would enable the root canal to be filled immediately. There is no attempt at root end closure. Rather an artificial apical stop is created. A number of materials have been proposed for this purpose including tricalcium phosphate (100, 101), calcium hydroxide (100, 102), freeze dried bone (103) and freeze-dried dentin (104). Favorable results have been reported. Recently there have been a number of reports describing the use of MTA in one-visit apexification. Witherspoon and Ham (105) describe a technique using MTA. They assert that MTA provides scaffolding for the formation of hard tissue and the potential of a better biological seal. They conclude that this technique is a viable option for treating immature teeth with necrotic pulps and should be considered as an effective alternative to calcium hydroxide apexification. Steinig, Regan and Gutmann (106) consider that the importance of this technique lies in the expedient cleaning and shaping of the root canal system, followed by its apical seal with a material that favors regeneration. Furthermore the potential for fractures of immature teeth with thin roots is
reduced, as a bonded core can be placed immediately within the root canal. A number of authors (95, 107, 108) have reported clinical success using MTA for one visit apexification.
Tooth restoration following apexification Although treatment of the immature apex is manageable, the thin dentinal walls, particularly in the cervical area, present a clinical problem. Should a second injury occur, teeth with thin dentinal walls are more susceptible to fractures that can render them nonrestorable. It has been reported that ~ 30% of these teeth will fracture during or after endodontic treatment. Consequently, some clinicians have questioned the advisability of the apexification procedure and have opted for more radical treatment procedures, including extraction, followed by expensive restorative procedures such as dental implants and a fixed partial denture. Because of the thin dentinal walls there is a high incidence of root fractures in teeth after apexification. Restorative efforts should be directed towards strengthening the immature root. A number of studies have demonstrated that the use of the newer dentin bonding techniques can significantly increase the resistance to fracture of these teeth to levels close to that of intact teeth (114). Goldberg et al. (115) have recently demonstrated the reinforcing effect of a resin glass ionomer in the restoration of immature roots. The risk of root fracture during apexification is a concern, but during this time it is essential that access to the apical portion of the canal is preserved. Katebzadeh et al. (116) have described a technique in which the access is restored with a composite restoration. A clear curing post is inserted into the soft composite and cured. The post is then removed leaving a patent channel for calcium hydroxide replacement and subsequent obturation of the canal.
Article 12 Nooshin Katebzadeh, B. Clark Dalton and Martin Trope 1998 Recent studies have shown that intracoronal acid-etched bonded resins can internally strengthen endodontically treated teeth and increase their resistance to fracture.
In fact, the newer dentin bonding systems can
strengthen endodontically treated teeth to levels close to that of intact teeth. This technique has been suggested as a restorative method to strengthen teeth against fracture subsequent to apexification. Because the apexification procedure takes up to 18 months to complete, these fractures may occur during active treatment, before obturation of the canal. Rabie et al suggested a modified acid etch technique to strengthen the tooth during the apexification procedure. No data currently exist supporting the clinical advantage of this strengthening technique.
MANAGEMENT OF OTHER PROBLEMS ASSOCIATED WITH THE IMMATURE APEX
Thin dentinal walls Without fracture - intraradicular rehabilitation glass ionomer cement composite With fracture - non surgical management calcium hydroxide intraradicular rehabilitation mineral trioxide aggregate - surgical management glass ionomer cement mineral trioxide aggregate - Extraction in untreatable cases
Frequent periapical lesions - Non surgical treatment calcium hydroxide intracanal medicaments - Surgical treatment
Fractures of crown - Full crowns with / without post and cores Discoloration in long standing cases - Post endodontic bleaching - Full crowns with / without post and cores
Conclusions Every effort should be made to attain the genetically programmed closure of the foramen that remains open because of early pulp death. This can be accomplished by apexification a method of recharging the growth potential and restoring root growth and foramen closure Calcium hydroxide apexification remains the most widely used technique for treatment of necrotic teeth with immature apices. Success rates are high. However techniques for one-visit apexification provide an alternative treatment option in these cases. Prospective clinical trials comparing these alternative techniques are required. Thus as can be seen from above, successful obturation of an incompletely developed non vital tooth forms only one part of the treatment for such teeth. Complete rehabilitation of these teeth requires that all the other associated problems be taken into consideration while formulating a treatment plan.
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