IMPLANT ANCHORAGE AND ITS CLINICAL APPLICATIONS
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
www.indiandentalacademy.com
INTRODUCTION IMPLANT TERMINOLOGY PARTS OF IMPLANT HISTORY OF IMPLANT CLASIFICATION OF IMPLANT ORTHODONTIC ANCHORAGE WITH OSSEOINTERGRATION;BONE PHYSCIOLOGY AND METABOLISUM IMPLANT-BONE INTERFACE INDICATION AND CONTRAINDICATIONS OF IMPLANT TREATMENT PLANNING TREATMENT CONSIDERATION RADIOGRAPHIC ANALYSIS APPLICATION OF IMPLANT IN ORTHODONTICS ORTHOPEDIC CORRECTION ENDOSSEOUS IMPLANT SUBPERIOSTEAL IMPLANTS OSSEOUS IMPLANT INTERDENTAL IMPLANTS LONG TERM STABILITY OF IMPLANT FUTURE OF IMPLANT CONCLUSION www.indiandentalacademy.com
INTRODUCTION Conservation of anchorage in totality has been a perennial problem to the traditional orthodontist.Conventional means of supporting anchorage have been using either intra-oral sites or relying on extraoral means. Both of these have their limitations – The extra-oral forces cannot be used on a 24x7 basis to resist the continuous tooth moving forces and are also taxing on the patient's compliance. On the other hand,strict reliance on intra-oral areas does not offer any significant advantages, except the fact that the patient's co-operation is less critical. Due to these constraints therefore, at times, either the treatment options start getting limited or the end result compromised. The advent of osseointegrated implants, due to the pioneering studies of Prof. Branemark has changed this scenario. The implants made of titanium have been widely used by several orthodontists as they offer Absolute Anchorage.
www.indiandentalacademy.com
IMPLANT TERMINOLOGY Implant: As defined by Boucher Implants are alloplastic devices which are surgically inserted into or onto jaw bone. Osseointegration: An intimate structural contact at the implant surface and adjacent vital bone, devoid of any intervening fibrous tissue - Branemark(1983).
www.indiandentalacademy.com
PARTS OF IMPLANT The commonly used implant screw/plate has two parts a) Implant head which serves as the abutment and in the case of an Orthodontic implant, could be the source of attachment for elastics/ coilsprings b) Implant body which is the part embedded inside bone. This may be a screw type or a plate type. The plate design that has been used in Orthodontics
www.indiandentalacademy.com
HISTORY OF IMPLANTS DAHL (1945) first published the use of subperiostel vitallium implant to effect tooth movement in dogs LINKOW (1966) described endosseous blade implants with perforation for orthodontic anchorage. KAWAHARA( 1975) developed Bioglass coated ceramic implant for orthodontic anchorage. THE BRANE MARK (1969, 1977) MENTOR OF MODERN IMPLANT SURGERY described the high compatibility and strong anchorage of titanium in human tissue and coined the term osseointergration Various bioactive ceramics such as glass ceramic (BROMER ET AL 1977,HENCH ET AL 1973) , tricalcium phoshate ceramic and hydroxyapatite ceramic (LUHR AND RIESS 1984)
www.indiandentalacademy.com
CREEKMORE(1983) reported the possibility of skeletal anchorage in orthodontics . ROBERTS(1989) used conventional two stage implant in the retromolar region to help reinforce anchorage successfully closing first molar extraction site in the mandible . After completion of the orthodontic treatment the implant were removed and histologically analysed . They found a high level of osseo integration had been maintained despite the orthodontic loading. HIGUCHI and JAMES ( 1991) used titanium fixtures for intraoral anchorage to facilitate orthodontics tooth movement. COSTA ET AL ( 1998) used miniscrew for orthodontic anchorage UMEMORI ET ET AL ( 1999) used SAS for open bite correction GIULIANO MAINO ( 2003) spider screw
www.indiandentalacademy.com
CLASSIFICATION OF IMPLANT Based on the location Subperiosteal ; In this design, the implant body lies over the bony ridge. This type has had the longest history of clinical trials but a decreased long-term success rate; probably due to the fact that the chances of getting it dislodged are high.Also, the complexity of their designs requires a precise casting procedure. The subperiosteal design currently in use for orthodontic purposes is the 'Onplant'
www.indiandentalacademy.com
Transosseous ; In this particular variety, the implant body penetrates the mandible completely. These have enjoyed good success rate in the past. However they are not widely used because of the possible damage to the intrabony soft tissue structures like the nerves and vessels . Even in the field of Orthodontics, transosseous implants have not been used
www.indiandentalacademy.com
Endosseous ; These are partially submerged and anchored within bone. These have been the most popular and the widely used ones. Various designs and composition are available for usage in specific conditions. The endosseous implants are most commonly employed types for orthodontic purposes.
www.indiandentalacademy.com
Based on the configuration design . Root form implants: These are the screw type endosseous implants and the name has been derived due to their cylindrical structure Blade / Plate implants: According to the composition Stainlesssteel Cobalt-Chromium-Molybdenum (Co-Cr-Mo) Titanium Ceramic Implants Miscellaneous such as Vitreouscarbon and composites According to the surface structure. Threaded or Non-threaded. Porous or Non Porous.
www.indiandentalacademy.com
Since 1995 over 10 new systems of implant have been introduced Based on the implant morphology: a) Implant discs i. Onplant b) Screw designs - These include: i. Mini-Implant ii. Orthosystem implant system iii.Aarhus implant iv. Micro-implant v. Newer systems such as the Spider screw, the OMAS system, the Leone miniimplant, the Imtec screw etc. c) Plate designs - These include: i. Skeletal Anchorage system (SAS) ii. Graz implant supported system i i i. Zygoma anchorage system II ) They can also be classified depending on the area of placement as: a) Subperiosteal Implants b) Osseous implants and c) Inter-dental implants www.indiandentalacademy.com
IMPLANT-BONE INTERFACE The relationship between endosseous implants and bone consists of one of two mechanisms:osseointegration,when the bone is in intimate contact with the implant, or fibroosseous integration, in which soft tissues, such as fibersand/or cells, are interposed between the two surfaces. The proponents of the fibro-osseous system of implant retention opinon that the presence of a dense collagenous tissue between implant and bone will act as an osteogenic membrane. There is no wide support, however, for this concept. The osseointegration concept proposed by Branemark et al and called functional ankylosis by Schroede . it states that there is an absence of connective tissue or any nonbone tissue in the interface between the implant and the bone. A more accurate term, microinterlock, is used in orthopedic implantology where tissue and implant are juxtaposed,providing a bioinert fixation with surface porositisity grooves, or beads. Osseointegration refers to the direct contact of bone and implant at the light microscope level . Osseointegration never occurs on 100% of the implant surface. Successful cases will have between 30% and 95% of the implant www.indiandentalacademy.com
Bone Tissue Three distinct types of bone (woven, lamellar, and composite) are involved in postoperative healing and maturation of the osseous tissue supporting an implant . Woven bone has high cellularity, a rapid formation rate (30 m/day or more), relatively low mineral density, high random fiber orientation an poor strength. It serves an important stabilization role in postoperative healing of endosseous implants . During the initial healing process woven bone fills all spaces at the bone-implant interface. Although capable of stabilizing an unloaded implant, woven bone lacks the strength to resist masticatory function. Lamellar bone is the principal load-bearing tissue of the adult skeleton. It is the predominant component of a mature bone-implant interface. Lamellar bone is formed relatively slowly (less than 1.0 m/day),has a highly organized matrix, and is densely mineralized. Composite bone is a combination of paravascular lamellar bone deposited on a woven bone matrix.. Formation of composite bone is an important step in achieving stabilization of an implant during the rigid integration process www.indiandentalacademy.com
Finite Element Analysis of Endosseous Implant and bone after vertical,horizontal and diagonal loading by Kobel and Harzer Three types of endosseous implants (all 9 mm in length and 3.3 mm in diameter, made of titanium) were used for this investigation. Type 1 was a simple, cylinder-shaped implant; type 2 a cylinder-shaped implant with a superperiosteal step; and type 3 a cylinder-shaped implant, subperiosteally threaded, with a superperiosteal step. The load on the implant was investigated under three conditions of bite and orthodontic forces from 0.01 to 100 N (vertically, horizontally, and diagonally). Vertical loading caused deforamtion of trabecular bone with all three implant geometries .Trabecular bone deformation was reduced by a superperiosteal step in the design. Horizontal loading of the implants shifted the deformation from the trabecular to the cortical bone. large deformation was measured at the transition from cortical to trabecular bone. The smallest deformations were found for implants with a superperiosteal step and diagonal loading . The use of threads provided no improvement in loading capacity.
www.indiandentalacademy.com
The healing potential for an implant is determined by three factors: (1) quality of bone at the site of implantation, (2) postoperative stability of the implant, and (3) degree of integration of the interface. If there is good postoperative stability of the implant in cortical bone, the healing response involves six physiological stages: I. Callus formation (0.5 month}-initial, 2. Callus maturation (0.5 to 1.5 months 3. Regional acceleratory phenomenon (RAP) (1.5 to 12 months) remodeling of the nonvital interface and supporting bone 4. Osseous integration of the interface (1.5 to 12 months)completion of the RAP, increased direct contact of living bone at the interface 5. Maturation of supporting bone (4 to 12 months)completion of the RAP, secondary mineralization of new bone and increased direct contact of living bone at the interface 6. Long-term maintenance of osseointegration
www.indiandentalacademy.com
INDICATIONS AND CONTRAINDICATIONS OF IMPLANTS
Indications for implant in orthodontics To retract and align anterior teeth with no posterior support To close edentulous spaces in first molar extraction sites To intrude or extrude teeth To protract or retract teeth of one arch To stabilize teeth with reduced bone support For orthopedic traction Implant for osteogenic distraction
www.indiandentalacademy.com
Contraindication for implant therapy Absolute contraindication Severe systemic disorder eg osteoporosis Psychiatric diseases eg psychoses dysmorphobia Alcoholics drug abusers Relative contraindications Insufficient volume of bone Poor bone quality Patients undergoing radiation therapy Insulin dependent diabetes Heavy smokers
www.indiandentalacademy.com
TREATMENT PLANNING Problem List and Patient Desires Initial Evaluation Chief compliant Medical/ Dental History Review Intra /Extraoral Examination Diagnostic Impression /Articulated Casts Radiographs (Panoramic and Periapical ,CT Scan or Tomography Photographs Treatment Options / Informed Consent
www.indiandentalacademy.com
TREATMENT CONSIDERATIONS Age of the patient The age of the patients is an important consideration as implant are problematic if inserted in growing children for the following reasons The use of implant in the anterior maxilla is contraindicated due to the possibility of the mid palatal suture being open Resorption in the posterior part of the maxilla resulting from growth changes could lead to the exposure of the implant into the sinus The posterior aspect of the mandible continues to undergo growth changes in all the plane of spaces and as such definitive implant placement in this area would be difficult to estimate
www.indiandentalacademy.com
Teeth- Number & Existing Conditions 1.Size shape & diameter of existing dention 2. Tooth & root angulation & proximity 3.More than 1.5 mm between implant and natural teeth Periodontium Bone support Quality – Best is the thick compact cortical bone with core of dens trabacular cancellous bone Quantity – 6mm buccal – lingual width with sufficient tissue volume
www.indiandentalacademy.com
The predictable use of implants as a source of orthodontic and dentofacial orthopedic anchorage requires a practical understanding of the fundamental principles of bone physiology and biomechanics. However, a careful evaluation of prospective patients is indicated because many candidates for implant-anchored orthodontics are affected by osteopenia, osteoporosis, or other medical problems. Optimal use of osseointegrated implants requires a thorough knowledge of bone biomechanics, particularly when the patient is skeletally and/or periodontally compromised
www.indiandentalacademy.com
An evaluation of bone metabolism is a key element of the diagnostic workup. The minimal screening procedure involves a careful medical history, evaluation of signs and symptoms of skeletal disease and an assessment of risk factors associated with negative calcium balance.The most prevalent metabolic bone diseases in middle-aged and older patients are: Renal osteodystrophy-poor bone quality (fibrousdysplasia) that is secondary to inadequate kidney function . Hyperparathyroidism-elevated serum calcium is often associated with highturnover osteopenia (low bone mass) secondary to a parathyroid adenoma . Thyrotoxicosis-high bone turnover leading to osteopenia, associated with hyperthyroidism orovertreatment of hypothyroidism . Osteomalacia-poor mineralization of osteoid due to a deficiency of the active metabolite of vitamin D (I, 25-dihydroxycholecalciferol) . Osteoporosis-usually defined as symptomatic osteopenia; most common fractures are of the spine, wrist, and/or hip. Fragility of other weight bearing joints such as the knee and ankle are also common problems. www.indiandentalacademy.com
Mucogingival problems Suffient volume is necessary Soft tissue heights of <2mm or> 4mm may present a challenge Oral hygiene Important pre and post implant placement Systemic manifestations 1.Diabetics are predisposed to delayed healing 2. Destructive habits â&#x20AC;&#x201C; smoking is contraindicatd to placement of implant as delayed or inadequate tissue healing and osseointergration is noted Radiographic analysis Periapical pathology Radioapaque/radiolucent regions above the inferior alveolar region or below the maxillary sinus Adequate space above IAN or below maxillary sinus Implant should be placed at a minimum of 2mm from the inferior alveolar canal or below the maxillary sinus Adequate interradicular area Bone quality and quantitiy www.indiandentalacademy.com
Radiographic analysis Periapical pathology Radioapaque/radiolucent regions above the inferior alveolar region or below the maxillary sinus Adequate space above IAN or below maxillary sinus Implant should be placed at a minimum of 2mm from the inferior alveolar canal or below the maxillary sinus Adequate interradicular area Bone quality and quantitiy
www.indiandentalacademy.com
APPLICATION OF IMPLANT IN ORTHODONTICS As a Source of Anchorage alone (Indirect anchorage) a. Orthopedic Anchorage - Maxillary Expansion - Headgear like effects b. Dental Anchorage Space closure of anterior teeth Intrusion of posterior teeth Distalization c. In conjunction with prosthetic rehabilitation (Direct anchorage).
www.indiandentalacademy.com
ORTHOPEDIC CORRECTION WITH IMPLANTS i) Maxillary Protraction ii) Maxillary Expansion However, these have been in experimental studies. i) Maxillary Protraction Smalley et al in 1988 used Branemark implants into the maxilla, zygoma, orbital and occipital bones of monkeys. A force of 600 gm was delivered to maxillary and zygomatic bones . A 12mm widening at the zygomaticomaxillary suture was seen and 16mm widening at zygomaticotemporal suture was observed. The dental changes seen were a 57mm change in overjet. However dental tipping also occurred along with skeletal protraction.
www.indiandentalacademy.com
ii) Implants for skeletal expansion In 1995 - Movassaghi et al tested frontonasal suture expansion in rabbits from an implanted titanium screw device. The plates were placed in frontal and nasal bones. After4 weeks of healing, 55 gm force was applied . Force was applied for 5 weeks and a significant increase in growth to the tune of 6 mm. across frontonasal suture was seen.
www.indiandentalacademy.com
In 1997 Andrew Parr et al conducted experiments on Midnasalexpansion using endosseous titanium screws. They divided the sample into 3 groups- 1 control and 2 experimental groups. 1 Nand 3N loading forces were applied in the two experimental groups. Their results showed a 92% stability of implants. Sutural expansion of 5.2mm and 6.8 mm respectively was seen in the 1N and 3N load categories. Mineral apposition and bone formation rates were significantly higher in the experimental group. The 3N group showed more expansion but this did not affect the rate of bone formation across the suture
www.indiandentalacademy.com
ENDOSSEOUS IMPLANT
Implants for dental anchorage
a) Implants for intrusion of teeth Creekmore in 1983 published a case report of usage of a vitallium implant for anchorage, while intruding the upper anterior teeth. The vitallium srew was inserted just below the anterior nasal spine . After an unloading period of 10 days, an elastic thread was tied from head of the screw to the arch wire. Within one year, 6mm intrusion was demonstrated along with 25 lingual torque .
www.indiandentalacademy.com
Another study by Southard in 1995 compared the intrusion 'potential of implants with that of teeth (denta1 anchors). Titanium implants were placed in extracted 4th premolar area in dogs, followed by an unloading period of three months. Then, an intrusive force of 50-60 gm via 'V' bend was effected. This was compared with intrusive potential of teeth on the other side using the same mechanics. No movement of implant was seen at the end of the experiment whereas, on the other side, the tooth acting as the anchor units tipped severely. Therefore, implants are definitely superior to the teeth acting as anchor units.
www.indiandentalacademy.com
b) Implants for space closure Extensive research relating to usage of retromolar implants for orthodontic anchorage has been done by Eugene Roberts.The first clinical trial was on an adult wherein an atrophic extraction site had to be closed. A special implant was developed of size 3.8mm width and 6.9 mm length, which was placed in the retromolar area. A 0.021" X .025" SSwire was used for used for anchorage from the screw around the premolar bracket . In the initial phases, this wire also aided in leveling . The extraction spaces were closed using forces from buccal as well as the lingual sides (activating the lingual arch. The premolar was prevented from moving distally with the help of 0.021 X . 025" wire acting as an anchorage. The modification in this technique as suggested by him in 1994 includes the usage of a .019" X.025" TMAwire. This wire is termed as the anchorage wire.
www.indiandentalacademy.com
www.indiandentalacademy.com
A Patient before treatment, showing missing mandibular first molar with mesial tipping of second and third molars into extraction site. B. Beginning of active treatment, with anchorage wire In place. C. Molars translated mesially with no appreciable distal movement of premolars. D. Five months after active treatment, 9mm of mesial translation of mandibular molar root apices www.indiandentalacademy.com
Although the retromolar implants popularised by Eugene Roberts are very efficient in preserving anchorage, they suffer from certain drawbacks, which in turn has hindered their acceptance in routine clinical practice. DISADVANTAGE OF ENDOSSEOUS IMPLANT The important limitations are: a) Bulkiness of the implant and therefore the nonsuitability of placement in the inter-dental areas. b) It involves a two stage procedure and therefore a long waiting time before loading the implant c) Anatomical limitations - such as erupting teeth, nerve canal etc. also add to their minimal usage d) Cost of the implants - These are the root form implants used for tooth replacement and therefore, very expensive. .
www.indiandentalacademy.com
SUBPERIOSTEL IMPLANT THE ONPLANT This is a classic example of a subperiosteal implant in Orthodontics. Developed byBlock and Hoffman in 1995, this system consists of a circular disc 8-10 mm in diameter with a provision for abutments in the center of the superficial surface . These abutments would enable the Orthodontist to carry out tooth movement against the Onplant. The undersurface of this Titanium disc is textured and coated with Hydroxyapatite (HA). The HA, being bioactive helps in stabilisation of the implant by improving integration with bone. The average thickness (height) of the implant is 3 mm .
www.indiandentalacademy.com
Method of Placement: The onplant is placed by a surgeon through a specialised procedure known asTunneling. After making an incision in the posterior region of the palate, a sub-periosteal tunnel flap is created extending till the desired location, using an elevator. Care is taken to position the onplant as close to the midline as possible. The onplant is not disturbed for a period of 3-4 months to allow bio-integration. Later, the superficial surface of the onplant is exposed using a trephine and the desired abutment is then threaded on . www.indiandentalacademy.com
www.indiandentalacademy.com
Studies on Onplants: Extensive animal studies have been carried out on onplants. They point out to the fact that onplants bio-integrate and can tolerate a maximum force of 161 Ibs. Block and Hoffman further suggest that these onplants could be used not only for dental anchorage; for eg: retraction of anteriors or distalising posteriors, but also for orthopedic traction. Human trials are however, limited Disadvantages of Onplants: a) A long waiting period prior to orthodontic force application b) Excessive surgical intervention - Two surgeries are necessary after onplant placement; one to uncover the onplant cover screw and the other to remove the onplant itself following Orthodontic treatment. c) Cost factor
www.indiandentalacademy.com
OSSEOUS IMPLANT Osseous implants are those that are placed in dense bone such as the zygoma, the body and ramus area or the mid-palatal areas. The implant systems under this category are the Skeletal Anchorage system, The Grazimplant supported system The Zygoma anchorage system
www.indiandentalacademy.com
SKELETAL ANCHORAGE SYSTEM The skeletal anchorage system was developed by Umemori and Sugawara Appliance design It essentially consists of titanium miniplates, which are stabilised in the maxilla or the mandible using screws. The earlier of these miniplates were the conventional surgical mini plates, which are used by Oral Surgeons for rigid fixation. The recent versions of these miniplates have been modified for attaching orthodontic elastomeric or coil springs. Different designs of miniplates are available and this fact offers some versatility in placing the implants in different sites. The 'L' shaped miniplates have been the most commonly used ones, while the 'T' shaped ones have been proposed for usage while intruding anterior teeth . The screws used for fixing the miniplate are usually 2-2.5mm in diameter
www.indiandentalacademy.com
www.indiandentalacademy.com
Method of Placement Titanium miniplates were implanted after a local anesthesia with intravenous sedation. First, a mucoperiosteal incision was made at the buccal vestibule directly under the first or second lower molars. The mucoperiosteal flap was then elevated, and the surface of the cortical bone at the apical region of the molar was exposed. An L-shaped miniplate was adjusted to fit the contour of each cortical bone surface and was fixed by bone screws (length, 5 mm or 7 mm) with the long arm exposed to the oral cavity from the incised wound (there are two holes in the long arm of the miniplate; the exposed hole will be used to directly receive the intrusive force).The implant was placed such that it did not interfer with mandibular movement.. All of the miniplates were transfixed at the region of the buccal vestibule. Loading was done after wound is healed.
www.indiandentalacademy.com
www.indiandentalacademy.com
Advantage of miniplates The shape of the miniplate can be adjusted to the type of tooth movement: intrusion of molars, intrusion of incisors, distalization or protraction of teeth, etc., and the thickness of the patientâ&#x20AC;&#x2122;s bone Position of the plate can be adjusted during the treatment It can be placed without destroying the teeth or bone The anchor plates are monocortically placed at the piriform opening rim, the zygomatic buttresses, and any regions of the mandibular cortical bone. The anchor plates work as the onplant and the screws function as the implant, SAS enables the rigid anchorage that results from the osseointegration effects in both the anchor plates and screws All portions of the anchor plates and screws are placed outside the maxillary and mandibular dentition, the SAS does not interfere with tooth movement
www.indiandentalacademy.com
Distalization of molars It is possible to distalize the mandibular molars with anchor plates placed at the anterior border of the mandibular ramus or mandibular body. Distalization of the mandibular molars enables the clinician to correct anterior crossbites, mandibular incisor crowding, and mandibular dental asymmetry without extracting premolars single molar distalization Extraction of the third molars is done to create the space for the molar distalization. After the buccal segments are leveled and aligned, stiff archwires . L-shaped anchor plates are placed at the anterior border of the mandibular ramus. Then the bands or brackets of the first molars are taken off, and a retractive force is applied to the second molars with an open coil spring. To avoid the side effects of the reciprocal coil spring, the first premolars must be firmly ligated with anchor plates. After the distalization of thesecond molars, distalization of the first molars is done with the same procedure.
www.indiandentalacademy.com
www.indiandentalacademy.com
En masse distalization of the entire buccal segments. Direct retractive force is applied from the anchor plates to the first premolars to perform en masse distalization of the buccal segments. Elastic modules or nickeltitaniumclosed coil springs usually provide the retractive orthodontic force
www.indiandentalacademy.com
Intusion of lower molar for correction of open bite Intrusion of the lower molars was achieved with the application of elastic orthodontic force on the SAS, Lingual crown torque was applied to the lower molars with Burstoneâ&#x20AC;&#x2122;s precision lingual arch to avoid buccal flaring during intrusion
www.indiandentalacademy.com
A) L-shaped miniplate for intrusion of molars B) L-shaped for distal movement of molars C) Y-shaped intrusion and distalizaton of maxillary molars D) Straight miniplate for intrusion of molars
www.indiandentalacademy.com
ADVANTAGE OF SAS The SAS enables tooth movement to be controlled 3-dimensionally, so that treatment goals can be accomplished, even when the amount of tooth movement required is more than the mesiodistal width of the premolars. SAS, it is not always necessary to extract the mandibular first or second premolars, even in patients with moderate to severe crowding. The molar relationship in patients with symmetric or asymmetric Class III molar relationships can be corrected without having to extract mandibular premolars
www.indiandentalacademy.com
ZYGOMA ANCHORAGE SYSTEM Hugo De Clerck and Geerinckx of Belgium introduced this system in 2002. Appliance design The upper part of the Zygoma Anchor is a titanium miniplate with three holes, slightly curved to fit against the inferior edge of the zygomaticomaxillary buttress . A round bar, 1.5mm in diameter, connects the miniplate and the fixation unit. A cylinder at the end of the bar has a vertical slot, where an auxiliary wire with a maximum size of .032" â&#x2039;&#x2026; .032" can be fixed with a locking screw. The plate is attached above the molar roots by three self-tapping titanium miniscrews, each with a diameter of 2.3mm and a length of 5mm or 7mm. The miniscrews do not need to be sandblasted, etched, or coated. Square holes in the center of the screw heads accommodate a screw-driver for initial placement, while pentagonal outer holes are used to remove the screws at the end of treatment.
www.indiandentalacademy.com
www.indiandentalacademy.com
Method of Placement To place the anchor, an L-shaped incision, consisting of a vertical incision mesial to theinferior crest of the zygomaticomaxillary buttress and a small horizontal incision at the border between the mobile and attached gingiva, is made under local anesthesia. The mucoperiosteum is elevated, and the upper part of the anchor is adapted to the curvature of the bone crest . Three holes with a diameter of 1.6mm each are drilled, and the Zygoma Anchor is affixed with the three miniscrews. The cylinder should penetrate the attached gingiva in front of the furcation of the first molar roots at a 90째 angle to the alveolar bone surface. The miniplate is covered by the mucoperiosteum and sutured with resorbable stitches
www.indiandentalacademy.com
CLINICAL APPLICATION Orthodontic forces can be applied to the anchor immediately after implantation. To connect the Zygoma Anchor with the anterior teeth, a rigid power arm was designed to fit in the large vertical slot of a canine bracket .The hook at the end of the power arm is situated at the level of the canineâ&#x20AC;&#x2122;s center of resistance. A nickel titanium closed-coil spring with a force of 50-100g is attached between the power arm on the canine and the Zygoma Anchor, so that the direction of force is parallel to the main archwire
www.indiandentalacademy.com
ADVANTAGE Miniscrews are small enough to be placed between the roots of the teeth in the alveolar bone. By connecting two or more miniscrews, the orthodontic reaction forces can be neutralized. The surgical procedure is uncomplicated because the screws are placed directly through the gingiva, without a mucoperiosteal flap, and can be loaded immediately after insertion. Miniscrews can be used in the anterior or posterior region and attached with elastics or coil springs to the fixed appliance for direct anchorage. Anchorage can be adapted to changing treatment needs in different parts of the dental arches. The ZAS uses three miniscrews, increasing total anchorage over other types of implants. The point of application of the orthodontic forces is brought down to the level of the furcation of the upper first molar roots. The vertical slot with the locking screw makes it possible to attach an auxiliary wire, which can move the point of force application some distance from the anchor. www.indiandentalacademy.com
DISADVANTAGE The main disadvantage of these screws is their proximity to the roots, which may be damaged during placement of the screws or when the adjacent teeth are displaced
www.indiandentalacademy.com
ORTHOSYSTEM IMPLANT Developed by Wehrbein, this is a titanium screw implant with a diameter of 3.3 mm inserted into the median palate or the retromolar regions of the mandible or the maxilla . The implants are surface treated with sand blasting and acid etching for reducing to improve integration. They are available in two sizes of 4 mm and 6 mm length. An 8- week waiting period has been suggested before applying forces onto this implant.
www.indiandentalacademy.com
GRAZ IMPLANT SUPPORTED PENDULUM Graz implant supported system introduced by Karcher and Byloff, this anchorage system consists of a modified titanium miniplate, with provision for four miniscrews, and two oval shaped cylinders. This was used mainly as a support for the Nance button of a pendulum appliance in the palate . This system can be loaded within 2 weeks to distalize and anchor maxillary first and second molars
www.indiandentalacademy.com
Appliance Design It consists of a simple surgical plate (15 X 10 mm) . Two cylinders (10 mm long and 3.5 mm in diameter) are soldered at right angles to the center of the plate. The plate is fixed to the palatal bone via four 5-mm-long titanium miniscrewsThe 2 cylinders perforate the palatal mucosa to enter the oral cavity .The entire anchorage device is constructed of 100% titanium. No auxiliary ,wires are bonded to the premolars,making the GISP removable . In the palatal portion of the resin body are 2 cylindric slots that correspond to the 2 cylinders . The system is based on a telescopic principle:the 2 slots of the removable pendulum (RP) are placed over the 2 fixed cylinders of the implant .
www.indiandentalacademy.com
CLINICAL APPLICATIONS Surgical placement and orthodontic procedure The surgeon exposes the anterior part of the palate for insertion of the anchorage plate by preparing a mucoperiosteal flap . If third molars are removed at the same time, the procedure is carried out under general anesthesia. The titanium plate with the 2 cylinders is fixed via four 5-mm-long titanium miniscrews to the bony palate in the median palatal area.
www.indiandentalacademy.com
The plate can be positioned so that the cylinders are positioned either mesiodistally along the palatal suture, or one to the right and one to the left (ie, rotated 90degrees). The area is then covered again with the flap, which has been incised to let the 2 cylinders pass through. After 1 to 2 weeks of healing, an impression is made of the maxillary arch and the palate , and a plaster model is made of the maxilla and titanium cylinders. The removable PA is fabricated in the laboratory and then placed onto the 2 cylinders in the patient's mouth.
www.indiandentalacademy.com
The TMA springs are extraorally activated prior to insertion to generate approximately 250 g of force at a 45-degreeangle . The RP is then slid onto the 2 cylinders , and the 2 TMA springs are introduced into lingual sheaths on the maxillary first molars. At the same time a 0.020- inch stainless steel round sectional wire is inserted into the tubes on the first and second molars. A nickeltitanium alloy (Ni-Ti) push-coil distalizes the second molar with approximately 100 g of force. Once the second molar is sufficiently distalized, the force of the push-coil is reduced to be barely active. The TMA spring of the RP is then stronger than the passive push-coil between the first and second molar. In this way the first molar is more effectively moved distally, since the force of the distalizing force is focused primarily on it, while the second molar is kept in the desired position.
www.indiandentalacademy.com
Advantages of Osseous implants: The osseous implants, specially the mini plate designs offer the Orthodontist a fair chance of success in effecting complex tooth movements such as molar intrusion. True intrusion of upper and lower molars in moderate anterior open bite casesconverts a borderline orthognathic case into an orthodontic one. This emerging new area of implant application has been termed as 'Orthognathic Orthodontics limitations of Osseous implants:
Disadvantage They need a fairly complex surgery and therefore have to be placed by a surgeon. The chances of infection are greater than the screw implants. Their removal is as difficult as the placement
www.indiandentalacademy.com
INTERDENTAL IMPLANTS These implants are endosseous implants but of smaller diameter, which allows placement in interdental areas. They rely more on mechanical retention than complete osseointegration. They are favoured over the retromolar implants due to the following reasons: a) Placement is very simple and can be done underL.A. b) They seem to be equally effective in resisting forces as the larger root form implants c) They can be used for bringing about all types of tooth movement and d) Removal is an uneventful procedure
www.indiandentalacademy.com
MINIIMPLANT Ryuzo Kanomi introduced the Mini-implant in 1997
Method of Placement After reflection of mucoperiosteal flap and denuding of bone, 2mm round bur used to make 1.5mm pit. Pilot drill used to enter bone same distance as length of mini-implant. Mini-implant inserted with accompanying screwdriver. Implant site sutured over. Gingival tissue exposed over head of mini-implant. Mucosal punch used to remove soft tissue surrounding head of mini-implant. Two-hole titanium bone plate attached to head of miniimplant and tied to bracket with ligature wire. After four months the implant is laoded
www.indiandentalacademy.com
Implant site sutured over.
Gingival tissue exposed over head of mini-implant.
Mucosal punch used to remove soft Two-hole titanium bone plate attached tissue surrounding head of minito head of mini-implant and tied to implant bracket with ligature wire www.indiandentalacademy.com
CLINICAL APPLICATION Conventional dental implants are 3.5-5.5mm in diameter and 11-21mm long. The mini-implant is only 1.2mm in diameter and 6mm long, making it much more useful in orthodontic applications. It is used for horizontal traction if placed on the alveolar ridge . The screw is inserted between the mesial and distal roots of a molar for molar intrusion it is placed in the palate, to provide anchorage for molar distalization. It can be used distraction osteogenesis, with the implant placed intraorally instead of extraorally.
www.indiandentalacademy.com
Placement of mini-implants for cuspid retraction.
Placement of mini-implants for molar intrusion
www.indiandentalacademy.com
ADVANTAGE OF MINIIMPLANT It is small enough to place in any area of alveolar bone, even apical bone. The surgical procedure should be easy enough for an orthodontist or general dentist to perform and minor enough for rapid healing. The implant should be easily removable after orthodontic traction
www.indiandentalacademy.com
MICROIMPLANT Site for microimplant placement In the Maxilla Several areas of the maxilla can be used for insertion. One location is the inferior surface of the anterior nasal spine, where the micro implant can be used for proclination of the incisors. The location can also be that of the onplant in the midpalatal suture, taking advan tage of the density and height of the cresta nasalis, where the bone structure is dense enough for retention of the implant.
www.indiandentalacademy.com
The anteroposterior position can vary slightly according to the individual anatomy.The orientation may likewise vary from almost vertical to an oblique anterior direction. It is, however, important to avoid the incisal canal, and when situated anteriorly, the miniscrew should be inserted a slight distance from the midline or more posteriorly. In this position the micro implant may render direct anchorage for retraction and intrusion of flared and ovcrerupted incisors. Anchorage in this location has also been used for symmetric mesial movement of lateral teeth when the anterior teeth could serve as anchorage. Indirectly this location can also be used for consolidating miniscrew anchorage with the teeth that are serving as anchorage but delivering too little resistance.
www.indiandentalacademy.com
Another location is in the Infrazygomatic crest. Level and direction may vary depending on the individual anatomy. From this position the zygoma wire and the implant can deliver anchorage for retraction and intrusion of anterior teeth. In addition, the screws can be placed so that they serve as anchorage for intrusion of molars that have over erupted secondarily to extraction of the occluding teeth. The force delivered with a micro implant anchorage will result in intrusion and buccal tipping, although the latter can be avoided with use of a lingual appliance with a one point.
www.indiandentalacademy.com
www.indiandentalacademy.com
In Mandible; Three different locations are suggested for use in the mandible. Roberts et al routinely placed micro implant in the retromolar position and established a satisfactory anchorage for mesial movement of molars, thereby avoiding retraction of thc anterior teeth in thc case of space closure following extraction of first molar. Roberts et al also used this position to neutralize the eruptive force generated in uprighting mesially tipped molars
www.indiandentalacademy.com
A second location is within edentulous areas of the alveolar proeess The purpose here would be to move single teeth without interfering with the remaining dentition. The micro implant can be inserted laterally in the molar and premolar region and can as anchorage for vertical and/or transverse movement of lateral teeth, molars, and premolars.
In the anterior region of the mandible the screws can be inserted into the symphysis to be used as anchorage for intrusion and protraction mandibular incisors. A miniscrew in this location can be useful as indirect anchorage by consolidating with a dental anchorage, as indicated by Kanomi.
www.indiandentalacademy.com
www.indiandentalacademy.com
Determination of screw placement site Nature of tooth movement required Direction of force to be at right angle to implant-non axial Bone depth at selected site Proximity of roots anatomical structures. Usaually a clinical estimate is adequate In doubt it is possible to plan on IOPA X ray Radiographic Index Crestal bone height Root Length Angulation of the teeth
www.indiandentalacademy.com
Surgical implant Index Prepare an acrylic jig in cold cure acrylic to fit the occlusal surfaces of adjacent teth 0.9mm ss orthodontic wires Mark likely spot on soft tissue with methylene blue indeliable marker or bleeding point Align tip of jig wire to this point IOPA X-ray with jig to determine suitability of site
ACRYLIC SURGICAL INDEX
RADIOGRAPHIC EVALUTION
www.indiandentalacademy.com
Measure Soft Tissue Thickness at Implant Site If loose tissue present then a need for incision . In firm tissue its possible to drill through the tissue Amount of tissue in palate will help you decide the implant length
Procedure For Microimplant Placement Aneasthesia for implant placement Soft local Infilitration usually adequate Soft tissue aneasthesia required Pain only if drill approximate roots Can be immediately redirected Palatal mucosa thickness can be checked with needle
www.indiandentalacademy.com
Surgical Incision If tissue soft and mobile a 5mm surgical incision to prevent rolling up of tissue Drill can be used to penetrate mucosa attached gingival and bone directly in firm tissue
Surgical site preparation Use a 1.5 mm drill Check for wooble /tight fit essential for mechanical retention Water coolant to prevent thermal bone cello trauma Speed 30-200 rpm
www.indiandentalacademy.com
Insertion of Micro implant Use slow speed pick up driver to engage screw into site Angulation of implant critical to success Maxillary implant need 30- 40 angulation to long axis of teeth buccally and palatally Increase the surface contact between screw and bone Improve retention Reduce risk of striking root Mandibular implant need 10 â&#x20AC;&#x201C; 20 angulation More cortical density Final positioning of implant Use long manual screw driver Clinical sensitivity to any resistance You may need to withdraw the implant and change direction in the event of encountering roots
www.indiandentalacademy.com
Immediate loading of implant Prevents micro motion Stabilises implant Micro implant Biomechanical considerations Non axial loading Direction of force at right angle Head to facilitate attachment Longer than convention Bone screw Larger moments at the implant head Stability of microimplants No perimplant bone loss due to mechanical loading Lateral loading â&#x20AC;&#x201C; increases in density of periimplant bone Nonaxial loading of upto 500gms- osseointergration
www.indiandentalacademy.com
SURGICAL PROCEDURE IN MAXLLARY ARCH
www.indiandentalacademy.com
A)L.AB)3-4mm incisionC)Reflection of flap with periostal elevatorsD)Hole made with pilot drillE) Micro implant in screw driverF)Micro implant screwed into placeG) After placement www.indiandentalacademy.com
Molar uprighting A micro-implant (1.2mm in diameter, 12mm in length) was placed in the maxillary tuberosity. A longer microscrew was used than in the lower retromolar area because the cortical bone is much thinner in the maxillary arch than in the mandibular arch. After two weeks of healing, 70g of force was applied with between the microscrew and lingual cleats on the buccal and lingual surfaces of the second molar . Four months later, the second molar showed considerable uprighting
www.indiandentalacademy.com
A micro-implant (1.2mm in diameter, 8mm in length) was placed in the retromolar area distal to the second molar, and a ligature wire was extended outward for elastomeric force application . To avoid root damage, only 50g of orthodontic force was applied . The molar was uprighted after eight months of treatment, and a bracket was bonded to it for further movement
www.indiandentalacademy.com
SPIDER SCREW The Spider Screw is a self-tapping miniscrew available in three lengths-7mm, 9mm, and11mm--in single-use, sterile packaging. The screw head has an internal .021" Ă&#x2014; .025" slot, an external slot of the same dimensions, and an .025" round vertical slot.
www.indiandentalacademy.com
It comes in three heights to fit soft tissues of different thicknesses: regular, with a thicker head and an intermediate-length collar; low profile, with a thinner head and a longer collar; and low profile flat, with the same thin head and a shorter collar .All three types are small enough to avoid soft-tissue irritation, but wide enough for orthodontic loading. The biocompatibility of titanium ensures patient tolerance, and the Spider Screw's smooth, self-tapping surface permits easy removal at the completion of treatment.
www.indiandentalacademy.com
Method of Placement The placement site should have enough bone depth to accommodate the screw length and at least 2.5-3mm of bone width to protect adjacent dental roots and anatomic structures such as the maxillary sinus or the inferior alveolar nerve. Typical insertion areas include the maxillary tuberosity, the retromolar areas, edentulous ridges, interradicular septi, the palate, and the anterior alveolar processes above the apices. A water-cooled 1.5mm pilot drill with a stop corresponding to the length of the Spider Screw is used to perforate the soft tissue and cortical bone . A low-speed hand piece should be used straight for anterior locations or contraangular for buccal or posterior locations..
www.indiandentalacademy.com
The Spider Screw is mounted on the pick-up device of a low speed contraangle for insertion at about 30rpm . A manual screwdriver is then used for final turning until the screw collar reaches its ideal position.If the screw location is surrounded by mucosa, a small, 5mm vertical incision can be made and the flaps separated without removing tissue or denuding alveolar bone. In areas where the bone is extremely compact, initial placement can be facilitated by using a 1.8mm bur to drill deeper and reach less compact bone.
www.indiandentalacademy.com
Once the screw has been inserted-especially in sites with poor bone quality it must be loaded immediately to promote mechanical stability. Because miniscrews rely on mechanical retention rather than osseointegration for their anchorage, the orthodontic force should be perpendicular to the direction of screw placement. Applied forces can range from 50g to 200g, depending on the quality of the bone and the orthodontic movement desired.If any mobility is noted immediately after placement or during tooth movement, the screw should be inserted deeper into the bone, or replaced with a longer screw to engage the opposite plate of cortical bone. For the first seven days, the patient should rinse with a 12% chlorhexadine solution. The Spider Screw is easily removed with a manual screwdriver, without local anesthetic in most cases
www.indiandentalacademy.com
MINISCREW ANCHORAGE SYSTEM(M.A.S) Developed by Incorvati ,Carano and et al Appliance design The screws used in the M.A.S. system are made of medical grade 5 titanium, they have a conical profile and are available in three diameters. Type A has a 1.3 mm diameter at the height of the neck of the implant, and 1.1 mm at the tip. Type B has a 1.5 mm diameter at the neck and 1.3 mm at the tip. The overall length for both Type A and Type B is 11.0 mm. Type C has a 1.5 mm at the neck and 1.3 mm at the tip with 9mm of total length.
www.indiandentalacademy.com
The head has a shape of two spheres ( 2.0 mm the lower sphere and 2.2mm the upper) that are fused together, with an internal hexagon for the insertion of the screw driver. There is a 0.6 mm aperture placed perpendicular to the length of the screw where a ligature wire or auxiliary monkey hook can be attached. In the junction point between the two circles, a slot is present for the attachment of elastics, chains or coil springs
www.indiandentalacademy.com
ADVANTAGE OF MINISCREW ANCHORAGE SYSTEM: . Independency from the number or position of the present teeth . Optimal use of the pulling forces . Independency from patient cooperation . Patient comfort . Shorter treatment time (not need to prepare dental anchorage) . Easyand fast screw insertion . Possible application even in interceptive therapy Advantages when compared with other osteointegrated systems: . VersatiIity in the insertion sites . Easyinsertion and removal . Immediate loading . Application in growing patients . Lowcost www.indiandentalacademy.com
Some potential complications common to other implant procedure are: . Lesions of some anatomic structures like nerves, vessels, dental roots. . Loss of the screw during the placement or during loading were lost during loading) . Inflammation around the implant site . Breakage of the screw within the bone duringinsertion or removal. This complication has probably be due to the use of screws with a small diameter
www.indiandentalacademy.com
CLINICAL APPLICATION Closure of Space For posterior space closure the anterior-posterior location of the miniscrew is between roots of the first molars and the second bicuspids roots. Vertically the miniscrew should be located at or above the mucogingival line depending on the desired line of action. For intrusion and distalization â&#x20AC;&#x201C;above the mucogingival line For distal movement â&#x20AC;&#x201C;at level of the mucogingival line Higher the screw in the maxilla the more perpendicular it is inorder to avoid damage to the maxillary sinus .Ideally it is 30- 40 degrees . In case the alveolar process is to prominent an auxillary attachment (monkey hook) is used it avoids discomfort and possible ulceration of the gums. In the mandibular arch care should be done to avoid the mental foramen.
www.indiandentalacademy.com
Symmetric intrusion of the incisors To intrude the upper incisors the screw is placed between the upper lateral incisors and the canines. The placement of the mini-screws should be done after leveling and alignment, in order to maximize the interadicular space at the placement site. In order to avoid tipping the upper incisors buccally during the intrusion, the end of thearchwire should be cinched back
www.indiandentalacademy.com
Correction of the cant of the plane of occlusion and of the dental midline The miniscrew is used to intrude the extruded canines and the laterals on the side of the cant, and to center the dental midline . During the intrusive movements, it is very important to center the mini-screws in between the roots of the teeth that need to be intruded in order to avoid the interferences between the teeth and the screw.
www.indiandentalacademy.com
Molar intrusion It is very hard to place the micro-screws precisely between the roots of first and second molars without interfering with the roots of the teeth either during implantation or during the intrusive movements. Moreover, sometimes the intrusion force need to be relatively high and more than one screw might be necessary in places where there is insufficient space available for the screw placement. For the above reasons it is suggested to limit the use of the miniscrews to cases where simple molar intrusion of one or two teeth
www.indiandentalacademy.com
Molar mesialization MAS is placed mesial to the space to be closed, at a height that facilitates a vector of force approximating the center or resistance of the molar, dental tipping can be avoided. The MAS can be placed after the initial leveling and aligning phase has been completed, so to use a full size arch wire that will prevent the mesial crown tippin of the molar during the space closure. The mesial movements are usually very slow especially in the lower arch so not more than 2-3 mm of mesial molar movement should be attempted.
www.indiandentalacademy.com
Intermaxillary anchorage Class II correctionis done by elastics or anterior repositioning appliances (i.e. Jasper Jumper, Bite Fixer, etc. There are numerous unwanted side effects of those kinds of mechanics, such as excessive anterior movement (proclination and protrusion) of the lower incisors and opening of the bite, . To address the above problems one alternative may be to place MAS between the roots of the first and second lower molars or between the root of the second bicuspids and lower first molars, in this way the upper arch can be retracted without any unwanted dental effects on the lower teeth. The placement of the MAS mesial to the lower molar may also prevent the mesial movement of the entire lower arch because the MAS, when in contact with the lower molar, may not allow it to move anteriorly. More research is needed to verify the clinical results
www.indiandentalacademy.com
LONG TERM STABILITY OF IMPLANT Miyawaki et.al analysed the success rate of three different screw sizes and a miniplate design. Their sample consisted of 51 patients who had 134 different implants used for conserving anchorage. The implants were in the form of screws(134 in number) of 1.0, 1.5 and 2.3 mm diameter as well as 17 miniplates.On one year after placement, they drew the following conclusions: a) The implant screws of 1 mm diameter had a high failure rate and are not recommended for clinical use as Orthodontic anchors. b) Implant screws of 1.5 and 2.3 mm diameter had reasonable success rates 84 and 86 % respectively and therefore could be used in majority of the cases. c) The miniplates had the best stability (96%), but the surgical intervention and patient discomfort was greater with these compared to miniscrews. Miniplates have beenrecommended in high angle patients. d) Peri-implant hygiene is one of the major factors, which could affect the stability of these implants.
www.indiandentalacademy.com
FUTURE OF IMPLANT The ideal implant design would be one that would be simple to place as well as remove, causing minimum discomfort to the patient. At the same time, they should be optimum in resisting the conventional Orthodontic forces. One would be looking at newer designs, which could be placed by an Orthodontist himself. Also, since the implants need not last for a very long time, biodegradable implants may be a lucrative option.Biodegradable screws made of L-polylactide have been introduced by Glatzmaier et al and are currentlyundergoing clinical trials. The system, termed as theBIOS (Bioresorbabale implant for Orthodontic systems)consists of resorbable polylactide with a metal abutment.
www.indiandentalacademy.com
CONCLUSION Implants for the purpose of conserving anchorage are welcome additions to the armamentarium of a clinical Orthodontist. They help the Orthodontist to overcome the challenge of unwanted reciprocal tooth movement. The presently available implant systems are bound to change and evolve into more patient friendly andoperator convenient designs.Long-term clinical trials are awaited to establish clinical guidelines in using implants for both orthodontic and orthopedic anchorage.
www.indiandentalacademy.com
Thank you www.indiandentalacademy.com Leader in continuing dental education
www.indiandentalacademy.com