VOLUME TEN NUMBER TWO FALL 1998
THE ROLE OF THE ORTHODONTIST ON THE MAXILLARY ANTERIOR IMPLANT TEAM
The Role of the Orthodontist on the Maxillary Anterior Implant Team
“Leave it to Beaver,” “My Little Margie,” “Happy Days” … “Those were the days my friend, we thought they’d never end …” Well, they have!!! In the past, replacement choices for a missing anterior tooth were simple and limited. The selec- tion included the “flipper” removable appliance, conventional fixed bridge- work, and the ever popular Maryland bridge.1,2 Preprosthetic preparation was usually limited to simple coronal space consolidation into the area of the eventual prosthetic unit. The rel- atively recent advent of the anterior implant has considerably improved the restorative options while simulta- neously complicating the therapeutic considerations. The successful place- ment and restoration of an anterior implant is dependent upon meticu- lous treatment planning coordinated among the orthodontist, surgeon, prosthodontist and general dentist.
Periodontal disease, caries, trauma, congenital absence are prominent in the list of etiological factors that can result in the loss of one or more ante- rior teeth. In the orthodontic prac- tice, congenitally missing teeth or traumatic loss are the most frequently encountered situations. Quite often, there is a superimposed malocclusion that requires comprehensive ortho- dontic correction prior to implant placement. In some particular Class II cases with considerable overjet, it may be possible to consider the orthodontic repositioning of the canines as missing lateral incisors while simultaneously reducing the overjet. However, this therapeutic option is often complicated or restricted by crown esthetics, inade- quate overjet or protraction anchor- age, and difficulty in dental midline control in unilateral cases.3 In some particular extraction cases character- ized by lower arch crowding and missing upper lateral incisors, consid- eration can be given to repositioning the maxillary canines as lateral incisors in order to obviate the need for removal of upper teeth and simultaneously balance the lower arch extractions. Anterior esthetic requirements, invasive involvement of adjacent teeth, and appliance breakage are just some of the compli- cations to be considered when choos-
ing conventional fixed or removable prosthetic replacements for anterior teeth. Consequently, the success of the single tooth implant replacement has become a warmly welcomed option for the treatment of this poten- tially complex problem.
Orthodontic treatment planning for the single tooth anterior implant involves the consolidation of an ideal amount of coronal space for the missing tooth while simultaneously creating an adequate mesio-distal interradicular space for the safe place- ment of the eventual implant. Ideal coronal space can be created by uti- lizing a compressed coil between the brackets on the teeth adjacent to the edentulous area (Fig. 1).
Obviously, inadequate space between adjacent roots could lead to surgical contact with root structure, resulting in serious potential compli- cations. The orthodontist must attempt to create at least 6mm of root separation in order to accommo- date a reasonably small implant safely (providing at least 1mm of clearance per side). The procedure becomes complicated by the necessity to maintain sufficient coronal replace- ment space, contact of adjacent crowns, and ideal anterior alignment while the roots are being diverged. Further complexity arises from the conical anatomy of the maxilla, which produces a narrower apical arc relative to the coronal arc resulting in a natural “lampshade” convergence of the roots (Fig. 2A,B).
The orthodontic creation of ade- quate interradicular space involves altering the normal bracket angula- tion, thereby producing the required root divergence. In the absence of a maxillary lateral incisor, the adjacent central incisor bracket is angulated mesio-gingivally while the adjacent canine bracket is overangulated disto- gingivally. Another option involves using the same canine compensation noted while placing a preangulated bracket from the opposite central incisor on the central incisor approxi- mating the implant side (e.g. placing a right central incisor bracket on a left central incisor adjacent to a miss- ing left lateral incisor). These alter- ations in bracket placement will cre- ate adequate root separation to per- mit the safe surgical placement of the implant (Fig. 3A,B,C,D,E).
Fig. 1 Compressed coil to create adequate coronal space for replacement
Fig. 2A,B Conical maxilla creates a “lamp- shade” effect resulting in convergence of roots.
Reangulation of brackets adjacent to implant site produces required root divergence for safe implant placement.
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However, the change in the cen- tral incisor angulation results in a separation of the central incisor crowns at their incisal edges as the contact point between the teeth migrates apically. Consequently, it may be necessary to perform a small amount of gingival interproximal stripping between the central incisors in order to achieve adequate closure at their incisal edges. During root reangulation, the central incisor brackets can be gently ligated togeth- er in order to prevent any severe space formation between the crowns. A closed coil between the brackets abutting the implant site will serve to maintain adequate coronal space for the eventual restoration. The reangu- lation of the central incisor also pre- cipitates a downward movement of the mesio-incisal edge of this com- pensated tooth. Incisal equilibration is often necessary in order to achieve a pleasing esthetic realignment of the incisal edges
to a line connecting the proximal cemento-enamel junctions of the teeth adjacent to this site will serve to produce the best gingival esthetics and stability.4 Frequently, the bone in the edentulous site has undergone atrophy resulting in inadequate bucco-lingual bone to accommodate an implant (Fig. 6A,B).
Careful examination of this area through a CT scan radiograph pro- vides the critical information that is essential in determining the necessity for bone augmentation/regeneration procedures prior to implant place- ment (Fig. 7).
Obviously, every effort should be made to try to preserve all available bone in the edentulous areas whenev- er implants are anticipated. Between the surgical phases of implant place- ment, temporary esthetics can be established by utilizing a removable retention appliance modified with an acrylic replacement tooth hollowed out palatally to accommodate the implant and the surgical site
Reangulation of brackets results in extrusion of mesio-incisal edge. Esthetic incisal equilibra- tion becomes necessary.
Occasionally, aberrant root mor- phologies, such as dilaceration or excessive width, may preclude the possibility of implant placement alto- gether.
There are osseous constraints that may complicate the successful surgi- cal placement of an implant. The surgeon must carefully calculate the dimensions of the bony housing that will eventually encase the implant. A failure in properly placing the implant can be the result if adequate measurements are not made bucco- lingually, inciso-gingivally and mesio-distally. An ideal inciso-gingi- val vertical distance of 2mm from the osseous crest of the edentulous area
Fig. 6A,B Bucco-lingual bone atrophy in the implant site may preclude safe implant placement.
The final restoration of the single tooth anterior implant is no easy task. The restorative dentist also faces numerous possible complications that may affect the form and angulation of the crown, the gingival margin and the single anterior crown esthet- ics. Proper orthodontic preparation of the adjacent roots combined with sound surgical intervention will greatly assist the restorative phase of treatment and help min-imize some of these potential pitfalls.5 The coordinated interdiscipli- nary cooperation between the orthodon- tist, surgeon, prostho-dontist and general den- tist can be the critical determining factor essen- tial for the placement of a predictable, functional and esthetic implant.
CT scan radiograph provides critical evaluation of bone in implant site.
Dilacerated roots may prevent safe implant placement.
The American Association of Orthodontists is a national dental specialty organization that was founded in 1900. The AAO comprises more than 13,000 members. Among its primary goals are the advancement of the art and the science of orthodontics; the encour- agement and sponsorship of research; and the achievement of high standards of excellence in orthodontic instruction, practice and continuing education.
Orthodontic Dialogue is published to help communicate with the dental pro- fession about orthodontics and patient care. Unless stated otherwise, the opin- ions expressed and statements made in this publication are those of the authors and do not imply endorsement by or official policy of the AAO. Reproduction of all or any part of this publication is prohibited without written permission of the AAO.
Correspondence is welcome and should be sent to: American Association of Orthodontists, Council on Com- munications, 401 N. Lindbergh Blvd., St. Louis, MO 63141-7816. The AAO Web site is www.aaortho.org.
Dr. Donald R. Poulton, President
San Francisco, California
Dr. Mervin W. Graham, President-Elect Denver, Colorado
Dr. Michael D. Rennert, Secretary-Treasurer Montreal, Quebec
Dr. Christopher W. Carpenter, Chair Council on Communications
Denver, Colorado
Dr. John R. Barbour, Chair Orthodontic Dialogue Subcommittee Carmel, Indiana
Ronald S. Moen, Executive Director
St. Louis, Missouri
Contributors to this issue:
Dr. John R. Bednar
Nashua, New Hampshire
Dr. Roger J. Wise
Swampscott, Massachusetts
The AAO recommends that every child should have an orthodontic screening no later than age seven.
During surgical implant phase of treatment, temporary esthetics can be established by a removable appliance with an acrylic replacement tooth.
Final anterior implant restoration by implant team (pre-treatment)
Final anterior implant restoration by implant team (post-treatment) (Courtesy of Dr. Ken Malament)
American Association of Orthodontists 401 N. Lindbergh Blvd.
St. Louis, MO 63141-7816
It must be remembered that patients are generally uncompromis- ing in their determination to obtain the highest quality and most esthetic anterior restoration possible … meticulous treatment planning will facilitate the achievement of these goals.
References
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- Artun, J., Zachrisson, B.: New technique for semipermanent replacement of missing incisors. Am. J. Orthod. 1984; 85:367-375.
- Marinello, C., et. al. Single tooth replacement: Some clinical aspects. Journal of Esthetic Dentistry 1997; Vol.9, No. 4:169-178.
- Woodworth, D., Sinclair, P., Alexander, R.: Bilateral congenital absence of maxillary lateral incisors: A craniofacial and dental cast analysis. Am. J. Orthod. Dentofac. Orthop. 1985; 87:280-293.
- Nevins, M., Mellonig, JT.: Implant Therapy: Clinical Approaches and Evidence of Success, Vol. 2:111-127. Nevins, M.; Stein, J.M.: The Placement of Maxillary Anterior Implants. Quintessence Publishing Co., Chicago, IL 1998.
- Arnoux, J.P.: Single tooth anterior implant: A word of caution, Part II. Journal of Esthetic Dentistry 1997; Vol. 9 No. 6:285-294.
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