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Orthodontic extrusion: Its use in restorative dentistry
Orthodontic extrusion: Its use in restorative dentistry David W. Ivey, D.M.D.,* Richard L. Calhoun, D.M.D.,** William Howard S. Dorfman, D.M.D.,**** and John E. Wheless, D.D.S.* Medical College of Virginia,
School of Dentistry,
B. Kemp, D.D.S.,***
Richmond, Va.
T
he use of orthodontic extrusion, also referred to as forced eruption, has met with limited use in restorative dentistry. Heithersay’ in 1973 and more recently Ingber’ have written articles on the use of forced eruption in the management of isolated nonrestorable teeth. This application of orthodontic movement results in tooth eruption that aids in lengthening of the clinical crown. Exposure of additional clinical tooth structure by periodontal surgery in the anterior portion of the dental arch is often discouraged due to the resultant compromise in esthetics and the possible adverse periodontal change to adjacent teeth. This is particularly true when extrusion of a single-tooth crown is required in an otherwise intact arch. The patients reported in this study demonstrate the concepts involved in establishing an esthetic result while maintaining a healthy periodontium. A brief discussion of this possible alternative to extraction is presented.
Fig. 1. A. Maxillary caries.
left lateral incisor with subgingival
CASE REPORTS Patient 1 A 29-year-old man needed root canal treatment of the maxillary left lateral incisor (Fig. 1, A). Examinations revealed extensive caries and a history of long-term pulpal exposure (Fig. 1, B). The carious process on the tooth approached the crestal bone interproximally, creating a questionable prognosis. Because the patient expressed a strong desire to retain this tooth in spite of the guarded prognosis, alternatives to extraction were considered. It was decided that orthodontic extrusion (forced eruption) The views 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. *Former Resident in Periodontics; now in private practice. **Former Resident in Endodontics; now in private practice. ***Associate Professor, Department of Endodontics. ****Associate Professor, Department of Periodontics.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 1. B. Radiograph of the maxillary prior to therapy.
left lateral incisor
401
IVEY ET AL.
Fig. 1, C to E. C, Polycarbonate crown in place following completion of root canal therapy and fabrication of a cast post and core. D, Orthodontic wire engaged to initiate eruption of the tooth. E, Five weeks later at completion of eruption. Note the bracket alignment.
Fig. I, F. Radiograph upon completion of the forced eruption. Note the change in radiodensity at the apex associated with root movement. 402
should be attempted. A rubber dam was placed, the caries excavated, and root canal treatment initiated. The endodontic treatment was completed at a subsequent appointment. A direct self-polymerizing post and core pattern was constructed, cast in gold, and cemented into place. A polycarbonate crown was temporarily placed (Fig. 1, C). Following pumicing and acid etching, mesh-backed orthodontic brackets were placed on both central incisors and the adjacent canine with direct bonding adhesive. A plastic bracket was bonded to the polycarbonate crown approximately 3 mm apical to the other brackets, and a multistrand orthodontic wire was positioned to engage all five brackets (Fig. 1, D). The patient returned in 2 weeks; the erupting incisor exhibited mobility and some degree of extrusion. By the fifth week the forced eruption. was complete (Figs. 1, E and F) and the crown was adjusted to prevent occlusal interference. After 6 additional weeks of stabilization, an evaluation was made regarding the need for a surgical crown extension procedure. This procedure was carried out under local anesthetic, utilizing inverse-bevel scalloped incisions and full-thickness facial and palatal flaps. Minimal osteoplasty was necessary to expose approximately 3 mm of sound tooth structure interAPRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
Fig. 1, G to I. G, The crown extension on the mesial aspect of the lateral incisor. H, Three weeks after surgery, the clinical crown exposure and poor marginal adaptation of the original temporary crown. I, Porcelain-fused-to-metal restoration in place.
proximally on the lateral incisor and allow an adequate dimension for periodontal connective tissue attachment (Fig. 1, G). The flaps were then placed at the crest of the alveolar margin and stabilized with 4-O silk suture. A periodontal dressing was placed and maintained for 7 days, and the postoperative course was without incident (Fig. 1, fo The final crown preparation and fabrication completed 4 weeks after surgery (Fig. 1, I).
was
Patient 2 An 18-year-old woman presented with extensive caries of the maxillary left lateral incisor (Fig. 2, A). Examination revealed previous root canal therapy in these teeth and carious lesions on the lateral incisor approaching the crestal alveolar bone. Full-thickness facial and palatal flaps were elevated to expose sufficient tooth structure for evaluation and caries excavation. A decision was made to extrude the left lateral incisor. Post and core direct patterns were fabricated, cast in gold, cemented, and followed by placement of temporary crowns. Direct bond wire-mesh brackets were placed on the two central incisors, the left lateral incisor, and THE JOURNAL
OF PROSTHETIC
DENTISTRY
the canine in a manner similar to that described for Patient 1. The bracket on the left lateral incisor, the tooth requiring eruption, was placed approximately 4 to 5 mm apical to the level of the other brackets. The twist wire was engaged and secured in position. Within 2 weeks the lateral incisor showed some eruption, and by the fourth week the orthodontic extrusion of approximately 4 to 5 mm was completed. The twist wire was left in place for retention for 6 additional weeks (Fig. 2, B). Due to unfavorable soft tissue contours that developed during the orthodontic movement, a periodontal flap procedure was deemed necessary. The procedure carried out was similar to that described in patient I, except that osteoplasty was not necessary (Fig. 2, C). Four weeks later the patient was evaluated (Fig. 2, U) and referred for placement of the final restoration.
Patient 3 A 20-year-old man was examined with a crownroot fracture of the maxillary right central incisor from a job-related incident (Fig. 3, A). Examination revealed an angular nature to the fracture that 403
IVEY ET AL.
Fig. 2. A, Maxillary left lateral incisor during the initial examination. B, Following eruption, the orthodontic wire was utilized for the 6 week retention period. C, The lateral incisor after eruption and immediately following soft tissue recontouring. D, Four weeks following soft tissue surgery and prior to placement of the final restorations.
involved the palatal root surface (Fig. 3, B). The following treatment options were considered: (1) extraction and placement of a three-unit fixed partial denture, (2) periodontal crown extension surgery, endodontic therapy, and fabrication of a single post-core crown, and (3) endodontic therapy, a post-core restoration, and forced eruption prior to the crown restoration. Because of the existing diastema, possible esthetic compromise, and the subcrestal involvement of the palatal root fracture, the forced eruption treatment plan was chosen. Following endodontic therapy and the cast postcore cementation, the eruption procedure was initiated, as described previously (Fig. 3, C). Three weeks later, after alignment with the multistrand wire, it was decided that further eruption was necessary, and a 0.02-inch arch wire with compensating bends was placed (Fig. 3, 0). After extrusion and a retention period, an apically positioned flap was utilized to correct the discrepancy in gingival height. After a total treatment time of 10 weeks, the final crown restoration was constructed without esthetic compromise (Fig. 3, E). 404
Patient 4 A 34-year-old man was seen 2 weeks following a pulpectomy and placement of a temporary post-core crown in a maxillary right lateral incisor. The reported that trauma patient, an endodontist, during a sporting event 13 years ago had resulted in a horizontal subossesous root fracture. His family dentist felt the tooth was nonrestorable, but advised against extraction at that time. The tooth remained comfortable and moderately mobile for 11 years. Within the previous 2 years mobility had increased. Two weeks prior to examination, the crown completely separated from the gingiva. Fig. 4, A is a copy of a radiograph made 1 year prior to crown loss. Extraction followed by a fixed partial denture or crown extension had been previously considered undesirable because of diastemas between the maxillary anterior teeth and because of the subcrestal level of root fracture, respectively. Still faced with these unesthetic features, forced eruption was chosen as a possible alternative. Following endodontic therapy, a post-core restoraAPRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
Fig. 3. A, The crown-root fracture of the maxillary right lateral incisor. B, The incisal and palatal dimensions of the crown-root fracture following minimal gingival resection to accommodate endodontic therapy and post preparation. C, Beginning of orthodontic extrusion with the multistrand wire engaging th.e apically positioned bracket of the right central incisor. D, Maxillary right central incisor in the final stage of eruption. Note that the gingival tissue has followed the erupting tooth (relative to adjacent incisors) creating a discrepancy in the coronal gingival height. E, Following extrusion and an apically repositioned flap, the right central incisor is ready for the planned crown restoration. tion, and placement of a temporary crown, forced eruption was initiated with the bracket on the involved tooth approximately 4 to 5 mm apical to the alignment of the adjacent teeth (Fig. 4, B). For 6 weeks no perceptible mobility or eruption was noted. However, within the next 3 weeks the desired movement occurred and the tooth was stabilized for 8 weeks. Prior to preparation for the crown restoration, a THE JOURNAL
OF PROSTHETIC
DENTISTRY
gingivoplasty was performed to facilitate refinement of the crown preparation. Subsequently the patient was referred for final restoration of the tooth (Fig. 4, c). DISCUSSION The orthodontic procedure described is a segmental approach that uses acid-etched orthodontic brackets and a very flexible multistrand wire. The 40.5
IVEY ET AL.
Fig. 4. A, A,Radiograph Radiograph of the maxillary right lateral incisor made I year prior to crown loss. B, B,’ At the onset of eruption, the orthodontic wire was placed approximately 4 to 5 mm out of line. C, Following completion of extrusion and retention, the patient was referred for the porcelain-fused-to-metal restoration. periodontal crown lengthening procedure that followed the extrusion in Patients 1 and 2 provided sufficient tooth structure for the restorative needs that followed. Several authors”-’ have described eruptive tooth movement resulting in a coronal shift of the supporting connective tissue attachment and alveolar bone. As demonstrated in Patients 2 and 4 this may not be a predictable occurrence, since ostectomy was not found necessary. However, when the attachment structures do follow the tooth coronally, the ostectomy necessary should include removal of only that alveolus which moved cosonally. Also, the gingival fibers that are stressed, posing a possible relapse problem, have to be severed during flap This closely parallels the rationale reflection. described by Edwards’. 7 in his transseptal fiber resections used to prevent postorthodontic rotational relapses of teeth. Restorative considerations that result from the narrow mesiodistal width of the extruded roots are
vitally important and have been described by Ingber.? Another restorative consideration that has received attention more recently is an anatomic area referred to as the biologic width.“, ” Palomo and Kopczyk” state that “at least 1% mm between the base of the sulcus and the crest of alveolar bone” should exist to maintain periodontal health. This area is said to allow for epithelial and connective tissue attachment to the tooth. Similarly, Ingber’ and Ingber and associate? state that at least 2 mm is needed for the connective tissue and epithelial attachment to maintain the biologic width. These authors discuss maintaining the biologic width and its importance in restorative dentistry. At present, the only histometric study available from which this concept is drawn was done by Gargiulo and associates”’ in 1961. Their findings are based on 30 human cadaver jaws containing 287 teeth of uncertain gingival health. Measurements were made
APRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
of the dentogingival junction areas, and the mean measurements were reported. These results are often referred to when determining the amount of tooth structure to be exposed in crown lengthening procedures. Perhaps further studies of a quantitative nature will help to clarify this concept. No clinical or experimental studies have demonstrated that infringement of this dentogingival junction will result in the loss of alveolar bone, provided the area is maintained plaque free. However, several studies”-’ ’ indicate that subgingival placement of crown margins results in increased inflammation. Silness’” reported that the degree of inflammation was directly proportional to the distance a crown margin is placed below the gingiva. In turn, inflammation was directly associated with the patient’s inability to control plaque subgingivally and maintain gingival health. In light of these studies it seems prudent to keep restorative margins supragingival whenever possible. Due to esthetic considerations of anterior teeth, patient acceptance often demands margins be placed into a healthy crevice, but minimal impingement seems advisable. ‘I‘he patients selected for treatment and reported demonstrate the minimum of time and materials needed in carrying out the procedures. Even more important is the concept of salvaging badly broken down teeth and restoring them to a state that allows the patient to maintain the health of the periodontium while satisfying cosmetic requirements. SUMMARY The technique described in this study demonstrates that the use of orthodontic extrusion can provide an alternative to extraction and extensive periodontal surgery. Selection of patients is an important aspect when considering this type of treatment. The crown-root ratio, as well as the root anatomy, if inadequate, may render this type of treatment inappropriate. The concept of a biologic width is discussed, and its application to forced eruption is described.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
REFERENCES 1. Heithersay, G. S.: Combined endodontic treatment of transverse root fractures in the region of the alveolar crest. Oral Surg 36:404, 1973. 2. Ingber, J, S.: Forced eruption: Part II. A method of treating nonrestorable teeth-periodontal and restorative considerations. J Periodontol 47:203, 1976. 3. Reitan, K.: Clinical and histologic observations on tooth movement during and after orthodontic treatment. Am J Orthod 53:721, 1967. 4. Oppenheim, A.: Artificial elongation of teeth. Am J Orthod 26:931, 1940. 5. Brown, I.: The effect of orthodontic therapy on certain types of periodontal defects. I. Clinical findings. J Periodontol 44:742, 1973. 6. Edwards, J. G.: A study of the periodontium during orthodontic rotation of teeth. Am J Orthod .X441, 1968. 7. Edwards, J, G.: A surgical procedure to eliminate rotational relapse. Am J Orthod 57335, 1970. 8. Palomo, F., and Kopczyk, R. A.: Rationale and methods for crown lengthening. J Am Dent Assoc 96:257. 1978. 9. Ingber, J., Rose, L., and Coslet. J.: The “Biologic Width”-A concept in periodontics and restorative dentistry. Alpha Omega, December 197i. 10. Gargiulo, A. W., Wentz, F. M., and Orban, B.: Dimensions and relations of the dentogingival junction in humans. J Periodontol 32:261, 1961. 11. Bergman, B., Hugosor, A., and Olsson, C. 0.: Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. A longitudinal twoyear study. Acta Odontol Stand 29:621. 1971. 12. Bjorn, A.: The relationship between the location of subgingival crown margins and gingival inflammation. J Periodonto1 45:151, 1974. 13. Newcomb, G.: The relationship between the location of subgingival crown margins and gingival inflammation. J Periodontol 45:151, 1974. 14. Miirmann, W.: Gingival reaction to well-fitted subgingival proximal gold inlays. J Clin Periodontol 1:120, 1974. 15. Silness, J.: Periodontal conditions in patients treated with dental bridges. III. The relationship between the location of the crown margin and the periodontal condition. J Periodont Res 5:225, 1970. Reprint requeststo: DR. Wnrr.w B. KEMP DEPT. OF ENDODONTICS MCV STATION Box 637 RICHMOND, VA. 23298
407
School of Dentistry,
B. Kemp, D.D.S.,***
Richmond, Va.
T
he use of orthodontic extrusion, also referred to as forced eruption, has met with limited use in restorative dentistry. Heithersay’ in 1973 and more recently Ingber’ have written articles on the use of forced eruption in the management of isolated nonrestorable teeth. This application of orthodontic movement results in tooth eruption that aids in lengthening of the clinical crown. Exposure of additional clinical tooth structure by periodontal surgery in the anterior portion of the dental arch is often discouraged due to the resultant compromise in esthetics and the possible adverse periodontal change to adjacent teeth. This is particularly true when extrusion of a single-tooth crown is required in an otherwise intact arch. The patients reported in this study demonstrate the concepts involved in establishing an esthetic result while maintaining a healthy periodontium. A brief discussion of this possible alternative to extraction is presented.
Fig. 1. A. Maxillary caries.
left lateral incisor with subgingival
CASE REPORTS Patient 1 A 29-year-old man needed root canal treatment of the maxillary left lateral incisor (Fig. 1, A). Examinations revealed extensive caries and a history of long-term pulpal exposure (Fig. 1, B). The carious process on the tooth approached the crestal bone interproximally, creating a questionable prognosis. Because the patient expressed a strong desire to retain this tooth in spite of the guarded prognosis, alternatives to extraction were considered. It was decided that orthodontic extrusion (forced eruption) The views 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. *Former Resident in Periodontics; now in private practice. **Former Resident in Endodontics; now in private practice. ***Associate Professor, Department of Endodontics. ****Associate Professor, Department of Periodontics.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 1. B. Radiograph of the maxillary prior to therapy.
left lateral incisor
401
IVEY ET AL.
Fig. 1, C to E. C, Polycarbonate crown in place following completion of root canal therapy and fabrication of a cast post and core. D, Orthodontic wire engaged to initiate eruption of the tooth. E, Five weeks later at completion of eruption. Note the bracket alignment.
Fig. I, F. Radiograph upon completion of the forced eruption. Note the change in radiodensity at the apex associated with root movement. 402
should be attempted. A rubber dam was placed, the caries excavated, and root canal treatment initiated. The endodontic treatment was completed at a subsequent appointment. A direct self-polymerizing post and core pattern was constructed, cast in gold, and cemented into place. A polycarbonate crown was temporarily placed (Fig. 1, C). Following pumicing and acid etching, mesh-backed orthodontic brackets were placed on both central incisors and the adjacent canine with direct bonding adhesive. A plastic bracket was bonded to the polycarbonate crown approximately 3 mm apical to the other brackets, and a multistrand orthodontic wire was positioned to engage all five brackets (Fig. 1, D). The patient returned in 2 weeks; the erupting incisor exhibited mobility and some degree of extrusion. By the fifth week the forced eruption. was complete (Figs. 1, E and F) and the crown was adjusted to prevent occlusal interference. After 6 additional weeks of stabilization, an evaluation was made regarding the need for a surgical crown extension procedure. This procedure was carried out under local anesthetic, utilizing inverse-bevel scalloped incisions and full-thickness facial and palatal flaps. Minimal osteoplasty was necessary to expose approximately 3 mm of sound tooth structure interAPRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
Fig. 1, G to I. G, The crown extension on the mesial aspect of the lateral incisor. H, Three weeks after surgery, the clinical crown exposure and poor marginal adaptation of the original temporary crown. I, Porcelain-fused-to-metal restoration in place.
proximally on the lateral incisor and allow an adequate dimension for periodontal connective tissue attachment (Fig. 1, G). The flaps were then placed at the crest of the alveolar margin and stabilized with 4-O silk suture. A periodontal dressing was placed and maintained for 7 days, and the postoperative course was without incident (Fig. 1, fo The final crown preparation and fabrication completed 4 weeks after surgery (Fig. 1, I).
was
Patient 2 An 18-year-old woman presented with extensive caries of the maxillary left lateral incisor (Fig. 2, A). Examination revealed previous root canal therapy in these teeth and carious lesions on the lateral incisor approaching the crestal alveolar bone. Full-thickness facial and palatal flaps were elevated to expose sufficient tooth structure for evaluation and caries excavation. A decision was made to extrude the left lateral incisor. Post and core direct patterns were fabricated, cast in gold, cemented, and followed by placement of temporary crowns. Direct bond wire-mesh brackets were placed on the two central incisors, the left lateral incisor, and THE JOURNAL
OF PROSTHETIC
DENTISTRY
the canine in a manner similar to that described for Patient 1. The bracket on the left lateral incisor, the tooth requiring eruption, was placed approximately 4 to 5 mm apical to the level of the other brackets. The twist wire was engaged and secured in position. Within 2 weeks the lateral incisor showed some eruption, and by the fourth week the orthodontic extrusion of approximately 4 to 5 mm was completed. The twist wire was left in place for retention for 6 additional weeks (Fig. 2, B). Due to unfavorable soft tissue contours that developed during the orthodontic movement, a periodontal flap procedure was deemed necessary. The procedure carried out was similar to that described in patient I, except that osteoplasty was not necessary (Fig. 2, C). Four weeks later the patient was evaluated (Fig. 2, U) and referred for placement of the final restoration.
Patient 3 A 20-year-old man was examined with a crownroot fracture of the maxillary right central incisor from a job-related incident (Fig. 3, A). Examination revealed an angular nature to the fracture that 403
IVEY ET AL.
Fig. 2. A, Maxillary left lateral incisor during the initial examination. B, Following eruption, the orthodontic wire was utilized for the 6 week retention period. C, The lateral incisor after eruption and immediately following soft tissue recontouring. D, Four weeks following soft tissue surgery and prior to placement of the final restorations.
involved the palatal root surface (Fig. 3, B). The following treatment options were considered: (1) extraction and placement of a three-unit fixed partial denture, (2) periodontal crown extension surgery, endodontic therapy, and fabrication of a single post-core crown, and (3) endodontic therapy, a post-core restoration, and forced eruption prior to the crown restoration. Because of the existing diastema, possible esthetic compromise, and the subcrestal involvement of the palatal root fracture, the forced eruption treatment plan was chosen. Following endodontic therapy and the cast postcore cementation, the eruption procedure was initiated, as described previously (Fig. 3, C). Three weeks later, after alignment with the multistrand wire, it was decided that further eruption was necessary, and a 0.02-inch arch wire with compensating bends was placed (Fig. 3, 0). After extrusion and a retention period, an apically positioned flap was utilized to correct the discrepancy in gingival height. After a total treatment time of 10 weeks, the final crown restoration was constructed without esthetic compromise (Fig. 3, E). 404
Patient 4 A 34-year-old man was seen 2 weeks following a pulpectomy and placement of a temporary post-core crown in a maxillary right lateral incisor. The reported that trauma patient, an endodontist, during a sporting event 13 years ago had resulted in a horizontal subossesous root fracture. His family dentist felt the tooth was nonrestorable, but advised against extraction at that time. The tooth remained comfortable and moderately mobile for 11 years. Within the previous 2 years mobility had increased. Two weeks prior to examination, the crown completely separated from the gingiva. Fig. 4, A is a copy of a radiograph made 1 year prior to crown loss. Extraction followed by a fixed partial denture or crown extension had been previously considered undesirable because of diastemas between the maxillary anterior teeth and because of the subcrestal level of root fracture, respectively. Still faced with these unesthetic features, forced eruption was chosen as a possible alternative. Following endodontic therapy, a post-core restoraAPRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
Fig. 3. A, The crown-root fracture of the maxillary right lateral incisor. B, The incisal and palatal dimensions of the crown-root fracture following minimal gingival resection to accommodate endodontic therapy and post preparation. C, Beginning of orthodontic extrusion with the multistrand wire engaging th.e apically positioned bracket of the right central incisor. D, Maxillary right central incisor in the final stage of eruption. Note that the gingival tissue has followed the erupting tooth (relative to adjacent incisors) creating a discrepancy in the coronal gingival height. E, Following extrusion and an apically repositioned flap, the right central incisor is ready for the planned crown restoration. tion, and placement of a temporary crown, forced eruption was initiated with the bracket on the involved tooth approximately 4 to 5 mm apical to the alignment of the adjacent teeth (Fig. 4, B). For 6 weeks no perceptible mobility or eruption was noted. However, within the next 3 weeks the desired movement occurred and the tooth was stabilized for 8 weeks. Prior to preparation for the crown restoration, a THE JOURNAL
OF PROSTHETIC
DENTISTRY
gingivoplasty was performed to facilitate refinement of the crown preparation. Subsequently the patient was referred for final restoration of the tooth (Fig. 4, c). DISCUSSION The orthodontic procedure described is a segmental approach that uses acid-etched orthodontic brackets and a very flexible multistrand wire. The 40.5
IVEY ET AL.
Fig. 4. A, A,Radiograph Radiograph of the maxillary right lateral incisor made I year prior to crown loss. B, B,’ At the onset of eruption, the orthodontic wire was placed approximately 4 to 5 mm out of line. C, Following completion of extrusion and retention, the patient was referred for the porcelain-fused-to-metal restoration. periodontal crown lengthening procedure that followed the extrusion in Patients 1 and 2 provided sufficient tooth structure for the restorative needs that followed. Several authors”-’ have described eruptive tooth movement resulting in a coronal shift of the supporting connective tissue attachment and alveolar bone. As demonstrated in Patients 2 and 4 this may not be a predictable occurrence, since ostectomy was not found necessary. However, when the attachment structures do follow the tooth coronally, the ostectomy necessary should include removal of only that alveolus which moved cosonally. Also, the gingival fibers that are stressed, posing a possible relapse problem, have to be severed during flap This closely parallels the rationale reflection. described by Edwards’. 7 in his transseptal fiber resections used to prevent postorthodontic rotational relapses of teeth. Restorative considerations that result from the narrow mesiodistal width of the extruded roots are
vitally important and have been described by Ingber.? Another restorative consideration that has received attention more recently is an anatomic area referred to as the biologic width.“, ” Palomo and Kopczyk” state that “at least 1% mm between the base of the sulcus and the crest of alveolar bone” should exist to maintain periodontal health. This area is said to allow for epithelial and connective tissue attachment to the tooth. Similarly, Ingber’ and Ingber and associate? state that at least 2 mm is needed for the connective tissue and epithelial attachment to maintain the biologic width. These authors discuss maintaining the biologic width and its importance in restorative dentistry. At present, the only histometric study available from which this concept is drawn was done by Gargiulo and associates”’ in 1961. Their findings are based on 30 human cadaver jaws containing 287 teeth of uncertain gingival health. Measurements were made
APRIL 1980
VOLUME
43
NUMBER
4
ORTHODONTIC
EXTRUSION
of the dentogingival junction areas, and the mean measurements were reported. These results are often referred to when determining the amount of tooth structure to be exposed in crown lengthening procedures. Perhaps further studies of a quantitative nature will help to clarify this concept. No clinical or experimental studies have demonstrated that infringement of this dentogingival junction will result in the loss of alveolar bone, provided the area is maintained plaque free. However, several studies”-’ ’ indicate that subgingival placement of crown margins results in increased inflammation. Silness’” reported that the degree of inflammation was directly proportional to the distance a crown margin is placed below the gingiva. In turn, inflammation was directly associated with the patient’s inability to control plaque subgingivally and maintain gingival health. In light of these studies it seems prudent to keep restorative margins supragingival whenever possible. Due to esthetic considerations of anterior teeth, patient acceptance often demands margins be placed into a healthy crevice, but minimal impingement seems advisable. ‘I‘he patients selected for treatment and reported demonstrate the minimum of time and materials needed in carrying out the procedures. Even more important is the concept of salvaging badly broken down teeth and restoring them to a state that allows the patient to maintain the health of the periodontium while satisfying cosmetic requirements. SUMMARY The technique described in this study demonstrates that the use of orthodontic extrusion can provide an alternative to extraction and extensive periodontal surgery. Selection of patients is an important aspect when considering this type of treatment. The crown-root ratio, as well as the root anatomy, if inadequate, may render this type of treatment inappropriate. The concept of a biologic width is discussed, and its application to forced eruption is described.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
REFERENCES 1. Heithersay, G. S.: Combined endodontic treatment of transverse root fractures in the region of the alveolar crest. Oral Surg 36:404, 1973. 2. Ingber, J, S.: Forced eruption: Part II. A method of treating nonrestorable teeth-periodontal and restorative considerations. J Periodontol 47:203, 1976. 3. Reitan, K.: Clinical and histologic observations on tooth movement during and after orthodontic treatment. Am J Orthod 53:721, 1967. 4. Oppenheim, A.: Artificial elongation of teeth. Am J Orthod 26:931, 1940. 5. Brown, I.: The effect of orthodontic therapy on certain types of periodontal defects. I. Clinical findings. J Periodontol 44:742, 1973. 6. Edwards, J. G.: A study of the periodontium during orthodontic rotation of teeth. Am J Orthod .X441, 1968. 7. Edwards, J, G.: A surgical procedure to eliminate rotational relapse. Am J Orthod 57335, 1970. 8. Palomo, F., and Kopczyk, R. A.: Rationale and methods for crown lengthening. J Am Dent Assoc 96:257. 1978. 9. Ingber, J., Rose, L., and Coslet. J.: The “Biologic Width”-A concept in periodontics and restorative dentistry. Alpha Omega, December 197i. 10. Gargiulo, A. W., Wentz, F. M., and Orban, B.: Dimensions and relations of the dentogingival junction in humans. J Periodontol 32:261, 1961. 11. Bergman, B., Hugosor, A., and Olsson, C. 0.: Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. A longitudinal twoyear study. Acta Odontol Stand 29:621. 1971. 12. Bjorn, A.: The relationship between the location of subgingival crown margins and gingival inflammation. J Periodonto1 45:151, 1974. 13. Newcomb, G.: The relationship between the location of subgingival crown margins and gingival inflammation. J Periodontol 45:151, 1974. 14. Miirmann, W.: Gingival reaction to well-fitted subgingival proximal gold inlays. J Clin Periodontol 1:120, 1974. 15. Silness, J.: Periodontal conditions in patients treated with dental bridges. III. The relationship between the location of the crown margin and the periodontal condition. J Periodont Res 5:225, 1970. Reprint requeststo: DR. Wnrr.w B. KEMP DEPT. OF ENDODONTICS MCV STATION Box 637 RICHMOND, VA. 23298
407