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INTRODUCTION TERMINOLOGY HISTORICAL PERSPECTIVE DENTAL IMPLANTS IN ORTHODONTICS CLASSIFICATION BENEFITS OF IMPLANTS IMPLANTS AS ANCHORAGE DESIGN OF IMPLANTS PLACEMENT SITES SURGICAL PROCEDURE SURGICAL GUIDES BONE- IMPLANT INTERFACE IMPLANT MAINTAINENCE LOADING PROTOCOLS OTHER APPLICATIONS MICROSCREW IMPLANT ANCHORAGE SLIDING MECHANICS PROBLEMS ENCOUNTERED SKELETAL ANCHORAGE SYSTEM CONCLUSION REFERENCES www.indiandentalacademy.com
Successful orthodontic treatment has always required intra oral anchorage with a high resistance to displacement. Extra oral traction can be an effective reinforcement, but demands exceptional patient co-operation. The size, bulk, cost and invasiveness of prosthetic Osseo integrated implants have limited their orthodontic application. www.indiandentalacademy.com
TERMINOLOGY • Anchorage : resistance to unwanted tooth movement. • Temporary anchorage device: device that is temporarily fixed
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to the bone for the purpose of enhancing orthodontic anchorage either by supporting the teeth of the reactive unit altogether, and is subsequently used. Implant : a titanium device placed in the bone that replaces the root of a tooth and enables the attachment of a prosthesis. Osseo integration : the attachment of bone to the surface of an implant. Immediate loading : a technique in which implants are restored, and thus, loaded at the time of their placement. www.indiandentalacademy.com
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500 B C –Etruscan population
600 A D Mayan population
1700’s John Hunter www.indiandentalacademy.com
1809 Maggiolo
Early 1960 LinkowVent -plant implant
Mid 1960’s – Blade vent implant
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Vitreous carbon implants
Flange fixture
Vitallium screw
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Implants can used in orthodontics , with following references
• Implants as a source of absolute
anchorage • Implants used for anchorage and as abutments for restorations • Implant site preparation improved by orthodontics • Implants in osteogenic distraction www.indiandentalacademy.com
Classification of implants can be based on : • Position of the implant can be subperiosteal, •
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transosseous, or endosseous . Titanium is the accepted ideal material for implant fabrication, but other variants include gold alloys, vitallium, cobalt-chromium, vitreous carbon, aluminum oxide ceramics, or nickelchromium-vanadium alloys. The implant surface maybe rough or smooth, and may have an additional hydroxyapatite or titanium-spray coating. www.indiandentalacademy.com
Implant materials
• Material must be : nontoxic, biocompatible,
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possess excellent mechanical properties, and provide resistance to stress, strain, and corrosion. 3 categories : Biotolerant (stainless steel, chromium cobalt alloys) Bioinert (titanium, carbon) Bioactive (hydroxyl apatite, ceramic oxidized aluminum) www.indiandentalacademy.com
Implant sizes Various sizes of implants: • Mini implants- 6mm long, 1.2mm in diameter • Standard implants- 6-15mm long, 3-5mm in diameter • Maximal load is proportional to the boneimplant contact surface. • Factors determining the contact area are length, diameter, shape, and surface design. www.indiandentalacademy.com
Implant shape • Determines the bone-implant contact area available for stress transfer and initial stability. Commonly used designs are: • Cylindrical or cylindrical- conical, with a smooth or threaded surface. • Degree of surface roughness is related to the degree of Osseo integration. www.indiandentalacademy.com
The main area of dispute focuses on how an implant gains its support from the surrounding bone. A screw thread around the implant surface aids loading of the surrounding bone in compression, whereas a smooth cylindrical design increases implant support when shear forces are exerted on the bone. Both these varieties show a more uniform stress distribution under loading when compared to other designs. www.indiandentalacademy.com
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HISTORY • In 1945, Gainsforth and Higley used vitallium screws and • • • • •
stainless steel wires in dog mandibles to apply orthodontic forces. 1964, Branemark et al observed a fixed anchorage of titanium to bone with no adverse tissue response. In 1969, Linkow placed blade implants to anchor rubber bands to retract teeth ,but he never presented long term results. In 1969, titanium implants were stable over 5 years and Osseo integrated in bone under light microscopy view. In 1984, Roberts et al , corroborated the use of implants in orthodontic anchorage by using titanium screws in rabbit femur. First clinical report in the literature of the use of TADs appeared in 1983, Creek more and Eklund used a vitallium bone screw to treat patient with deep impinging overbite. www.indiandentalacademy.com
TEMPORARY ANCHORAGE DEVICES
Biocompatible Osseo integration
Dental implant Palatal implant
Biological Osseo integration – ankylosed teeth
Mechanical retention
Fixation screws Mini screw Fixation wire
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Mechanical - Dilacerated teeth
Osseo-integrated implants and orthodontics • In malocclusions requiring a high level of anchorage control, •
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Osseo-integrated implants can be used on a temporary basis to minimize loss of anchorage. Roberts et al, used conventional, two-stage titanium implants in the retro molar region, to help reinforce anchorage whilst successfully closing first molar extraction sites in the mandible. After completion of the orthodontic treatment, the implants were removed using a trephine and histologically analyzed. They found a high level of Osseointegration had been maintained, despite the orthodontic loading. In another study, Turley et al. used tantalum markers and bone labeling dyes in dogs to illustrate the stability of twostage implants in cases of orthodontic or orthopedic traction. This work also showed that one-stage implants were less successful in this role. www.indiandentalacademy.com
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Benefits of implants in treatment of malocclusions Retracting and realigning anterior teeth with no posterior support. Closing edentulous spaces in first molar extraction sites. Centre-line correction when missing posterior teeth. Re-establishing proper transverse and anteroposterior position of isolated molar abutments. Intruding/extruding teeth. Protraction or retraction of one arch. Stabilization of teeth with reduced bone support. Orthopedic traction. www.indiandentalacademy.com
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Block and Hoffman addressed the issue of bone height by developing a disc-like structure called an ‘onplant’ , which is designed to be placed under local anesthetic. This hydroxyapatitecoated disc is 10 mm in diameter by 3 mm thick, and is placed subperiosteally on the posterior aspect of the hard palate, using a ‘tunneling’ surgical procedure
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Wehrbein and Merz have developed the Straumann Orthosystem implant (Institute Straumann AG, Walden burg, Switzerland), which can be up to 6mm in height, based on the potential bone depth available. The Orthosystem implant is a one-piece device with an 8-week healing period. It is composed of a screw-type endosseous section of between 4mm and 6mm in length (depending on palatal depth), a cylindrical transmucosal neck and an abutment, to which a transpalatal arch attaches.
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The increasing desire for early loading of implants used for orthodontic anchorage led Melsen et al to develop the Aarhus implant. Due to its small dimensions (6 mm length), this titanium anchorage screw can be located in multiple sites, including between the roots of teeth. It is said to allow Osseo-integration to occur even in the presence of immediate orthodontic loading, providing the orthodontic forces (25–50 g from Sentalloy springs) pass through the screw. The strain that develops in the bone surrounding the loaded screw leads to a local environment in which increased bone formation results. Due to the size of the screw it can be used in a number of different locations and can be easily removed when no longer required. www.indiandentalacademy.com
This is a self tapping , commercially pure titanium miniscrew. The screw can be immediately loaded with forces in the range of 50 to 300g. available in either 1.5mm or 2.0mm diameter. The 1.5mm comes in lengths of 6, 8, or 10mm. The 2.0mm comes as 7, 9, or 11mm lengths. The placement of screw requires sufficient bone depth of at least 2.5mm to protect the anatomic structures.
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Kanomi has described a mini-implant, which is 6 mm in length and 1.2 mm in diameter. This was developed from a mini-bone screw used for fixing bone plates, is screwed into the alveolus under local anesthetic, to within 3 mm of the apices of the teeth. Subsequent to healing and Osseo-integration, a titanium bone plate is fixed to the screw, and acts as a hook for the attachment of an orthodontic ligature wire to aid intrusion of the respective teeth. Due to potential oral hygiene problems, the ligature is not attached directly to the implant.
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maxilla BELOW NASAL SPINE
PALATE
INFRAZYGOMATIC CREST www.indiandentalacademy.com
RETROMOLAR AREA AND MOLAR AREA
ALVEOLAR PROCESS
Mandible
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SYMPHYSIS
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Surgical guide for optimal positioning of mini implant
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Pre- surgical evaluation
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Acrylisation
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Self drilling method www.indiandentalacademy.com
Self tapping method- attached gingival area
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Self tapping method – movable mucosal area
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Bone – implant interaction • Endosseous implantation in to cortical bone elicits a • • •
unique sequence of modeling and remodeling events that are critical to healing, adaptation, and long term maintenance of the bone implant interface. Callus formed at the endosteal and periosteal surfaces is the first vital bone to contact the implant. Initial healing response is driven by release of local chemical factors such as PDGF, TGF-ß and PGs. Remodeling of bone- implant interface is of importance because it is the mechanism for forming a vital interface between the implant and host bone.
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Peri implant bone response to orthodontic loading - Oyonarte et al :AJO august 2005. • Smaller amounts and less variability in crestal bone loss were
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seen in porous surface implants compared with machine threaded implants in both control and orthodontically loaded subjects. Orthodontic loading does not seem to affect the amount of direct bone-to-implant contact with Osseo integrated implants. Implant surface design appears to be an important determinant of peri implant bone remodeling with dental implants used as orthodontic anchorage units. Sintered , porous surface implants show more favorable patterns of bone remodeling under orthodontic loading compared with machine threaded implants, suggesting that shorter implant lengths still maintain Osseo integration. www.indiandentalacademy.com
Drill free Vs Drill type implants Drill free advantages: • Reduce operative time • Lower morbidity • Less invasive • DF had more bone –to-implant contact and a larger bone area than D type. • DF had increased level of bone remodeling and Osseo integration. www.indiandentalacademy.com
• For easy removal, low torque is needed
which is proportional to the square of screw radius. • Removal torque is directly proportional to screw radius and bone contact area, which is proportional to screw radius under same bone contact ratio. • When screw radius reduces to one-third/ one-fourth, the removal torque is decreased by one-ninth / one-sixteenth. www.indiandentalacademy.com
As bone density increases, the resistance created by the stress surrounding the screw becomes important in removal than in insertion of the screw. At removal, the stress is concentrated in neck, which may lead to fracture.
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CLINICAL APPLICATIONS OF THE MINISCREW IMPLANT
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Correction of cant occlusal plane
Alignment of dental midlines Extrusion of impacted canines Molar intrusion Molar distalisation Molar mesialisation
Symmetrical incisor intrusion
Intermaxillary anchorage
Closure of extraction spaces
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Closure of extraction spaces
If both intrusive and distalizing forces are needed , miniscrew should be positioned above the mucogingival line.
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If the primary movement is to be a distalising vector, the miniscrew should be placed at mucogingival line.
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•Miniscrew placed high in maxilla must be more perpendicular to bone to avoid damaging maxillary sinus •If screw head is at mucogingival level, it should be inclined a 30- 450 to interradicular bone
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Symmetrical incisor intrusion
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Correction of canted occlusal plane
The screws inserted between upper lateral incisor and canines, upper canines and premolars, or lower lateral incisor and canines www.indiandentalacademy.com
Miniscrew must be centered between roots of teeth to be intruded to avoid interference between teeth and screw
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Alignment of dental midlines
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Extrusion of impacted canines
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Molar intrusion
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Molar distalisation
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Molar mesialisation
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Inter maxillary anchorage
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Upper third molar alignment
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IMPLANT MAINTENANCE
• After surgery, the surrounding soft tissues must be maintained to ensure longevity of implant. Plaque accumulation near the gingival margin can cause perimucositis. Prolonged inflammation leads to breakdown of bone around implants and peri implantitis. Therefore , patient is instructed to follow daily plaque control at home and have periodic professional care. www.indiandentalacademy.com
SCREW LOADING PROTOCOLS • Implants fulfill the criteria for primary stability, but also
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withstand the stress and strain applied. There are substantial differences between orthodontic and occlusal forces. Orthodontic loads are continuous, horizontal, and usually 20 to 300g. Occlusal loads are discontinuous, vertical and are up to some kilograms. To discuss the maximal load, evaluating the design of the fixtures, the biomechanical requirements, the anatomic limitations and , the degree of Osseo integration is needed. www.indiandentalacademy.com
HOW LONG SHOULD WE WAIT BEFORE LOADING?
• If the implants are planned for future prosthetic
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abutments, a standard healing protocol should be followed. Direct orthodontic forces generate less stress on implants due to limited force impose (300gm). With dense bone and satisfactory stability, immediate loading might be feasible. Threaded implants provide superior mechanical interlock as compared with cylindrical designs. Thus, waiting time should be longer for non threaded implants. www.indiandentalacademy.com www.indiandentalacademy.com
Implant vs. Screw Loading Protocols in Orthodontics
A Systematic Review Elizabeth Ohashi; Oscar E. Pecho; Milagros Moron; Manuel O. Lagravere The Angle Orthodontist: Vol. 76, No. 4, pp. 721–727.
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Eleven articles fulfilled the selection criteria established. Five studies involved the use of implants while six involved the use of screws for orthodontic purposes. • Conclusions: Loading protocols for implants involve a minimum waiting period of 2 months before applying orthodontic forces while loading protocols for screws involve immediate loading or a waiting period of 2 weeks to apply forces. Success rates for implants were on average higher than for screws. www.indiandentalacademy.com
• The short waiting period for healing and Osseo integration after screw insertion is because of mechanical retention that is initially obtained. This gives the screws a sufficient primary stability to resist orthodontic loading forces, ranging between 30 and 250 g used in different orthodontic movements. • This short waiting period is sufficient for healing but not for Osseo integration, which is an important factor in maintaining a rigid anchorage unit. www.indiandentalacademy.com
• Histologically, it has been demonstrated that the premature load generates the formation of fibrous tissue between the bone and the screw. This layer of tissue gives the mechanical retention for the screw to not displace in the direction of the applied force. • In some cases, this layer of tissue can become granulation tissue because of the short time given for the formation of a correct Osseo integration. www.indiandentalacademy.com
• Forces applied to implants or screws,should
be proportional to the amount of Osseo integration, which at the same time depends on the surface contact between material and osseous tissue. • Factors that are involved : increase in surface are length, diameter, and shape of the appliance. • According to Favero et al, there is an inverse relationship between length and diameter where if the length decreases, the diameter should increase. www.indiandentalacademy.com
• Liou et al demonstrated that the screws
are clinically stable but not absolutely stationary when forces are loaded on them. • The screws mostly move toward the direction of the applied force, ranging from −1 to 1.5 mm displacement. • For this reason, it is recommended that they should be placed 2 mm away from any vital anatomical structure (roots, nerves). www.indiandentalacademy.com
The following conclusions should be considered with caution because only a secondary level of evidence was found. • Loading protocols for implants involve a waiting period of a minimum of 2 months before applying orthodontic forces. • Loading protocols for screws involve immediate loading or a waiting period of 2 weeks to apply orthodontic forces. • The success rates for implants were, on average, higher than for screws. www.indiandentalacademy.com
Implants used for anchorage and as abutments for restorations • Cases requiring implants for both restorative • •
management and orthodontic anchorage require extensive planning involving the orthodontist, restorative specialist, oral surgeon, and periodontist. There are cost and time implications, and the potential surgical difficulties of access and local anatomy that may prejudice against the ideal positioning of a conventional implant should be borne in mind. The dimensions of the implant should conform closely to the desired emergence profile of the final restoration without compromising the inter-dental bone. For optimal aesthetics of the emergence profile, the implant head should be 2 mm below the cemento-enamel junction of the adjacent teeth. www.indiandentalacademy.com
Implant site preparation improved by orthodontics
• When there has been bone loss associated with
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periodontal disease, which can significantly affect the aesthetic outcome and prognosis of implant treatment. Teeth that are compromised beyond the scope of periodontal treatment can be used to develop the alveolar bone in that region, through orthodontic traction, to allow the subsequent use of implants. This ‘forced orthodontic eruption’ of such a hopeless tooth causes an alteration in the soft tissue architecture of the periodontium as well as improving the amount and quality of bone www.indiandentalacademy.com available for implant placement.
Implants in osteogenic distraction
• Pilot studies on the maxilla and mandible,
undertaken by Ueda et al have illustrated the use of Osseo-integrated implants to transfer continuous distraction forces through the full width of the distraction site. This has been successfully completed in mandibular lengthening, maxillary advancement, and alveolar ridge augmentation but requires further research prior to becoming an established technique www.indiandentalacademy.com
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Step-by-step procedure MAXILLARY ARCH:
• Placement of microscrew implant into the alveolar bone • • •
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between II premolar and I molar on both sides. Bonding of 0.022 PEA and transpalatal bar for maintaining arch form. Partial canine retraction; a canine tied back to the microscrew implant. En masse retraction of 6 anterior teeth via 0.016×0.022 archwire hooks ; NiTi closing coil spring conncts the anterior hooks to the microscrew implant and applies 150g of force on each side. Finishing; occlusal settling with vertical elastics. www.indiandentalacademy.com
Mandibular arch • Placement of microscrew implant between the first and • • • •
second molars on both sides. Partial canine retraction; the canine is tied back to the second premolar. En masse retraction of 6 anterior teeth via 0.019×0.025 inch archwire. Application of an intrusive force to upright and intrude the mandibular molars by ligating an elastic thread from implant to mandibular archwire. Finishing
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Controlling the mode of anterior tooth retraction are: • Occlusogingival position of the implant, the height of the anterior hooks, and the amount of torquing curve given on the arch wire. • Implant placed low position -4mm gingival to arch wire distalizing force in non extraction cases • Position at 8-10mm gingival to arch wire retraction of anteriors in extraction cases www.indiandentalacademy.com
Characteristics of MIA sliding mechanics
• Allows bodily retraction of 6 anteriors,
while utilizing the force near the center of resistance. • Induce early changes of profile. • Uprighting and intrusion of mandibular molars induce autorotation of mandible. • Reduces treatment time. www.indiandentalacademy.com
COMMON PROBLEMS ASSOCIATED WITH MINI IMPLANTS 1. Screw related problems 2. Operator related problems 3. Patient related problems
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Screw related problems 1. Screw can fracture if it is too narrow or the neck area is not strong enough to withstand the stress of removal. The solution is to choose a conical screw with a solid neck and a diameter appropriate to the quality of bone. 2. Infection can develop around the screw if the transmucosal portion is not entirely smooth. www.indiandentalacademy.com
Operator related problems • Application of excessive pressure during • • •
insertion of a self drilling screw can fracture the tip of the screw. Over tightening can cause it to loosen. It is crucial to stop turning the screw as soon as the smooth part of the neck has reached periosteum. With a bracket like screw head , the ligature should be placed on top of the screw in the slot perpendicular to the wire. It is important not to wiggle the screw driver when removing it from screw head. www.indiandentalacademy.com
Patient related problems • • •
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The prognosis for primary stability of a mini implant is poor ,in cases where the cortex is thinner than 0.5mm and the density of trabecular bone is low. In patients with thick mucosa, the distance between the point of force application and the center of resistance of the screw will be greater than usual, thus generating a large moment when a force is applied. Loosening can occur , even after primary stability has been achieved, if a screw is inserted in an area with considerable bone remodeling because of either resorption of a deciduous tooth or post extraction healing. Mini implants are contra indicated in patients with systemic alteration in the bone metabolism due to disease, medication , or heavy smoking www.indiandentalacademy.com
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MINIBONE PLATES: THE SKELETAL ANCHORAGE SYSTEM • The SAS comprises of bone plates and fixation screws. They are made of commercially pure titanium that is biocompatible and suitable for Osseo integration. • The anchor plate consists of 3 components – the head, the arm and the body. • The head component is exposed intra orally and positioned outside of the dentition so that it does not interfere with tooth movement. The head has 3 continuous hooks for attachment of orthodontic forces. Two different types of head based on direction of hooks. • The arm is transmucosal and in 3 lengths- short (10.5mm), medium(13.5mm), long(16.5mm). www.indiandentalacademy.com
The body is positioned sub- periosteally and in 3 configurations- T plate, Y- plate and I plate
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• Maxillary sites : zygomatic buttress and
piriform rim • Mandible: lateral cortex in most locations except adjacent to mental foramen. • Y plate maxilla at zygomatic buttress to intrude and distalise upper molars • I plate in piriform opening for intrusion of upper anteriors or protraction of upper molars. • T or L plate placed in body of mandible to intrude , protract or distalise lower molars. At anterior border of ascending ramus to extrude impacted molars. www.indiandentalacademy.com
Advantages • • • • • •
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Made of pure titanium , its safe and stable. Do not disturb any kind of tooth system as placed outside dentition. Easy control of occlusal plane. Patient compliance not needed Significant advantage it allows the achievement of predictable three dimensional molar movements. Timing of orthodontic treatment: orthodontic force is applied about 3 weeks after implantation procedure, but before the Osseo integration of the titanium screws are implants. Immediately after orthodontic treatment , all anchor plates are removed. www.indiandentalacademy.com
The concept of temporary anchorage device is a relatively new application of more established clinical methodologies. Although the clinician can look to the literature for many answers, much is unknown and will only be answered by well designed prospective basic science and clinical trials. The future development of temporary anchorage devices for orthodontic anchorage will establish a more complete understanding of biology and biomechanics associated with both Osseo integrated and non integrated devices. www.indiandentalacademy.com
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Contemporary orthodontics. Proffit Biomechanics in orthodontics. Rvindra nanda. Rasmussen RA. The Branemark System of Oral Reconstruction: a colour atlas. Ishiyaku EuroAmerica Inc., Tokyo, 1992. Gainsforth BL, Higley LB. A study of orthodontic anchorage possibilities in basal bone. Am J Orthod Oral Surg 1945; 31: 406–11 Sherman JA. Bone reaction to orthodontic forces on vitreous carbon dental implants. Am J Orthod 1978; 74: 79–87. Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod 1997; 31: 763–767 Liou EJ, Pai BC, Lin JC. Do miniscrews remain stationary under orthodontic forces?. Am J Orthod Dentofacial Orthop. 2004; 126:42–47. Costa A, Raffini M, Melsen B. Micro-screws as orthodontic anchorage. Int J Adult Orthod Orthognath Surg. 1998; 13:201–209. MOREa et al. Surgical guide for optimal positioning of mini-implants. CO 2005;39:317-321. Cousley and parberry. Combined cephalometric and stent planning for palatal implants.JO 2005;32: 20-25. Shapiro and kokich. Uses of implants in orthodontics. DCNA 1988;32: 539-549. Huang et al. dental implants in orthodontics. AJO 2005; 1127:713-722. www.indiandentalacademy.com
•Hyo-Sang park et al. Microscrew implant anchorage sliding mechanics. WJO 2005; 6: 265-274. •Hee- moon kyung. Development of orthodontic micro implant for intra oral anchorage. JCO 2003; 37:321-328. •Trisi and Rebaudi. Progressive bone adaptation of titanium implants during and after orthodontic load in humans.int. j of perio. Res.2002;22:31-43. •Arbuckle et al Osseo integrated implants and orthodontics. Oro max. clin NA.1991;3:903-911. •Carano etal. Clinical applications of the miniscrew anchorage system. JCO 2005;36: 9-23.
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