Anterior mandibular subapical osteotomy: A useful treatment for patients with severely worn mandibular anterior teeth Stephen M. Schmitt, DDS, MS,a Robert J. Cronin, Jr., DDS, MS,b and Stefan Berg, MD, DDW USAF Medical Center, Wiesbaden, Germany, Wilford Hall U.S. Air Force Medical Center @GDP), Lackland AFB, Tex., and Cologne, Germany Rehabilitation of patients with severe dental wear is a complex diagnostic and restorative problem. As wear occurs, space for restorative materials is lost, and unique treatment techniques are needed to provide good esthetics and function. Use of orthognathic surgery to reposition mandibular anterior teeth and supporting alveolar bone can create a more ideal environment for restorative procedures. (J

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T reatment

with severe tooth wear is a complex and challenging problem. As teeth wear they may erupt and move into new positions, complicating an already difficult restorative problem. Lack of space for materials and the inability to create adequate resistance and retenof patients

tion forms make restorative procedures difficult. Use of the mandibular subapical osteotomy, however, allows teeth

and supporting alveolar bone to be repositioned into proper relationship with the remaining occlusion and creates adequate space for esthetic and functional restorations. A number of techniques have been used to create space for restorative materials: (1) increasing the vertical dimension of occlusion; (2) lengthening the clinical crown by periodontal surgery; (3) placing margins of restorations as far into the sulcus as possible without

damaging the epithelial

attachment; (4) using the pulp canal space for retention after endodontic procedures have been performed; (5) using auxiliary retentive features; (6) surgically positioning the teeth and supporting alveolar bone in the proper occlusal relationship; (7) orthodontically repositioning teeth; and (8) reducing opposing surfaces by enameloplasty. Accurate diagnostic procedures must be used to determine which combination of techniques are indicated for a given patient. DIAGNOSIS Panoramic, cephalometric, and full-mouth series of radiographs are generally required. Careful evaluation of interocclusal distance, phonetics, facial appearance, and

Fig.

1. Pretreatment clinical view of severely worn denti-

tion.

cephalometric tracings can help determine where space has been lost and which mode of treatment will be successful. Diagnostic casts should be mounted with a face-bow in a semiadjustable articulator. It is important to remember that the cephalometric radiograph and casts that are mounted with a face-bow are interrelated. The cephalo-

metric radiograph can indicate the relationship of the dental structures to the cranial base, soft tissues, and known normal values. The mounted casts give an accurate three-dimensional relationship of the teeth to the rotational centers and the opposing occlusal surfaces. These mounted casts can also be sectioned to reposition teeth and supporting

The views and opinions expressed herein are those of the authors and do not necessarily reflect the views of the United States Air Force or the Department of Defense. aLieutenant Colonel, U.S. Air Force (DC); Chief, Department of Prosthodontics, USAF Medical Center, Weisbaden, Germany. bColonel, U.S. Air Force (DC); Chairman, Department of Prosthodontics, Wilford Hall U.S. Air Force Medical Center (SGDP). cOral surgeon, Cologne, Germany.

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structures

to diagnose

result. Turner and Missirlian’

the final

treatment

noted that patients with exces-

sive tooth wear could be divided into three categories. Cat-

egory 1 patients were those who had lost occlusal vertical dimension. These patients could have their teeth restored using restorations made at an increased vertical dimension of occlusion. Category 2 patients had excessive wear without loss of occlusal vertical dimension but with space for

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Fig.

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2. Diagnostic wax-up and cast surgery to determine proper form for final rehahili-

tation. 3. Cast mandibular splint is constructed from a second diagnostic cast. Anterior segment is positioned in the same place as diagnostic wax-up.

Fig.

4. Segment of bone is removed below the apices of the anterior teeth to allow for apical repositioning. Fig. 5. Cast splint positions teeth and alveolar bone correctly for healing.

Fig.

restorative materials. This group was more complex to treat, but with the use of an ideal tooth preparation, enameloplasty, crown-lengthening periodontal surgery, and proper occlusal relationships, rehabilitation could be accomplished. Category 3 patients had excessive tooth wear without loss of vertical dimension but with limited space available. These patients are the most difficult to treat because space must be created using more complex, expensive, and time-consuming techniques. Orthodontic treatment, surgically repositioning segments of bone and teeth, endodontic therapy, periodontal crown lengthening, and increasing the vertical dimension of occlusion even though intermaxillary space had not been lost, may all be needed to rehabilitate teeth in these patients. Both Turner and Missirlianl and Dawson2 noted that segments of teeth and alveolar bone could be surgically re-

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positioned to create space for restorative materials. Frequently, mandibular teeth not only wear but also erupt into a more coronal position with respect to the rest of the teeth in the arch. To create the proper esthetic and functional final result, these teeth must be moved into a more apical position. This article describes treatment used to rehabilitate a category 3 patient with the mandibular subapical osteotomy as the primary method used to accomplish this goal. TREATMENT Fig. 1 illustrates a patient with severe wear of mandibular teeth opposed by porcelain fused-to-metal fixed partial dentures. The patient required: (1) an increase in the vertical dimension of occlusion of 0.5 mm; (2) endodontic treatment of the mandibular anterior teeth and placement 469

Fig. Fig. Fig. Fig.

6. 7. 8. 9.

Clinical view 2 weeks after surgery. Cast dowel and cores are made using an indirect technique. Provisional restorations are a useful guide for the final rehabilitation. Completed rehabilitation.

of cast post and cores; (3) surgical repositioning of mandibular anterior teeth and alveolar bone to a more apical position; and (4) restoration of all the remaining teeth with porcelain fused-to-metal and cast glass restorations. After analysis of diagnostic information, wax was added to the casts to determine the final form of the rehabilitation (Fig. 2). This diagnostic wax-up was duplicated in artificial stone and was used to make matrices to create provisional restorations. A second diagnostic cast was used to make a cast metal splint. The cut segment of this cast must be placed in the same exact position as the diagnostic wax-up (Fig. 3). A thin coat of die spacer (15 to 20 pm) should be placed on the teeth so as to ensure proper seating of the casting at the time of surgery. The splint should cover the occlusal surfaces of all teeth in the segment to be moved to allow accurate positioning at the time of surgery. Extreme care should be used in making this casting since it cannot be tried in the mouth until the time of surgery and it must fit accurately.

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The biologic basis and the surgical technique for the mandibular subapical osteotomy have been described by Obwegeser,3Kole,4 Bell et al.5-7and others.* If teeth are to be endodontically treated for restorative reasons (construction of cast dowel and cores), then endodontics should be completed prior to surgery. Should the apex of a tooth be accidentally cut during surgery, difficulties in canal obturation are then eliminated. Once the anterior segment has been mobilized, a segment of bone can be removed to allow apical repositioning (Fig. 4). The cast splint can then be positioned to ensure proper positioning of the segment (Fig. 5). The cast splint is retained in position with circummandibular wires and intermaxillary fixation is not required. This cast splint provides stable fixation and patient comfort. Frequently, normal occlusal contacts are established even though the patient is wearing the splint, because the segment has been repositioned more apically (Fig. 6). If numerous cast dowel and core foundation restorations

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must be made, the patterns can be fabricated in the dental laboratory using the indirect technique. This allows the patterns to be fabricated using a matrix from the diagnostic wax-up as a guide for proper form. The cast dowel and cores must be carefully fitted to the master cast (Fig. 7). Provisional acrylic resin restorations should reproduce the contours of the diagnostic wax-up and serve as a guide for the construction of the final rehabilitation (Fig. S).gBy using a mandibular subapical osteotomy, good esthetics, contours, and function can be created (Fig. 9). The mandibular incisor teeth were restored with cast glass crowns (Dentsply International Inc., York, Pa.), and all other restorations were porcelain fused-to-metal.

SUMMARY Treatment of patients with severe tooth wear is a complex and challenging task. Diagnosis is the key to success. Inadequate space for restorative materials is a common problem, and the mandibular subapical osteotomy can be a useful tool to create space and esthetics, and to correct abnormal occlusal relationships.

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REFERENCES 1. Turner KA, Miiirlian DM. Restoration of the extremely worn dentition. J PRCISTHETDENT 1984$2:467-74. 2. Dawson PE. Evaluation, diagnosis, and treatment of occlusal problems. 2nd ed. St. Louis: CV Mosby Co, 1989;511-13. 3. Obwegeser H. The surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. Part I. Surgical procedures to correct mandibular prognathiim and reshaping of the chin. Oral Surg 1957;10:677-89. 4. Kole H. Surgical operations on the alveolar ridge to correct occlusal abnormalities. Oral Surg 1959;12:277-88. 5. Bell WH, Condit CL. Surgical-orthodontic correction of adult bimaxillary protrusion. Oral Surg 1970;2&578-84. 6. Bell WH, Dann JJ. Correction of dentofacial deformities by surgery in the anterior jaws. Am J Orthod 1973;64:162-73. 7. Bell WH, Levy BN. Revescularization and bone regeneration after anterior mandibular osteotomy. Oral Surg 1970;28:196-203. 8. Johnson JV, Hinds EC. Evaluation of teeth vitality after subapical OSteotomy. Oral Surg 1969;27:256-7. 9. Schmitt SM, Brown FH. A rationale for management of the dentogingival junction. J PROSTHET DENT 1989;62:381-5. Reprint

requests

to:

COL. ROBERT J. CRONIN, JR. CHAIRMAN, DEPARTMENT OF PROSTHODONTICS WILFORD HALL USAF MEDICAL CENTFZ/SGDP LACKLAND AFB, TX 78236-5300

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