Nonextraction treatment with temporary skeletal anchorage devices to correct a Class II Division 2 malocclusion with excessive gingival display Makoto Nishimura, a Minayo Sannohe, b Hiroshi Nagasaka, c Kaoru Igarashi, d and Junji Sugawara e Sendai and Saitama, Japan, and Farmington, Conn The patient was a 22-year-old Japanese woman who complained of a gummy smile. She had several other or- thodontic problems, including crowding of the maxillary anterior teeth, retroclination of the maxillary central in- cisors, excessive maxillary incisor display, a deep overbite, Class II dental relationships, a Class II profile, and a long face. Two options for the correction of these problems were proposed. The first option was to extract the maxillary first premolars to correct the Class II relationship and implant a miniscrew to correct the gingival display; the second option was to place 2 miniplates for distalization of the maxillary molars and a miniscrew to correct the gingival smile without premolar extractions. The patient chose the second option. After placing a preadjusted bracketed system, 2 miniplates were placed in the zygomatic buttresses bilaterally with monocort- ical screws, and 1 miniscrew was fixed between the root apices of the maxillary central incisors. Distalization and intrusion of the maxillary molars and intrusion of the maxillary incisors were simultaneously started with those temporary skeletal anchorage devices functioning as absolute orthodontic anchors. The total treatment period was approximately 22 months. Her orthodontic problems were corrected. According to the cephalometric eval- uation, the entire maxillary dentition was significantly distalized, and her maxillary incisors were successfully intruded, with the mandible showing a slight counterclockwise rotation. Thanks to the temporary anchorage de- vices combined with miniplates and a miniscrew, we were able to predictably achieve her treatment goals without premolar extractions, orthognathic surgery, and the need for patient compliance. (Am J Orthod Dentofacial Orthop 2014;145:85-94) T he prevalence of Angle Class II Division 2 maloc- clusion is relatively low in comparison with other malocclusions. 1-3 This malocclusion is generally characterized by retroclination of the maxillary incisors, a deepbite, and an obtuse interincisal angle. 4 In the treatment of a Class II Division 2 malocclusion, the improvement of a deepbite with a gummy smile is a challenging treatment objective. Conventional ortho- dontic methods, such as an intrusive arch, have been used to reduce overbite, often resulting in undesirable extrusion and flaring of the posterior teeth. 5 The clock- wise rotation of the mandible caused by the extrusion of the posterior teeth worsens the Class II convex profile in many patients and also leads to an increase in the inci- dence of relapse for adults. 6-10 Extraoral appliances to reduce overbite, such as the J-hook, are effective in controlling the anchorage, but it is difficult to predict the final result in uncooperative patients. 11 There is a clear need for a procedure for patients with deepbite and excessive gingival display resulting a gummy smile that effectively intrudes the maxillary incisors without undesirable side effects and without their cooperation. The successful use of temporary skeletal anchorage devices (TSADs) as absolute anchorage to reduce over- bite in nongrowing patients has been reported. 12,13 However, no case report has detailed the simultaneous intrusion of the anterior teeth to correct a gummy smile and distalization of the maxillary posterior teeth to correct molar relationships. a Assistant professor, Division of Oral Dysfunction Science, Graduate School of Dentistry, Tohoku University, Sendai, Japan. b Private practice, Saitama, Japan. c Lecturer, Division of Maxillofacial Surgery, Graduate School of Dentistry, To- hoku University, Sendai, Japan. d Professor, Division of Oral Dysfunction Science, Graduate School of Dentistry, Tohoku University, Sendai, Japan. e Visiting clinical professor, Division of Orthodontics, Department of Craniofacial Science, School of Dental Medicine, University of Connecticut, Farmington, Conn; chief orthodontist, SAS Orthodontic Centre, Ichiban-cho Dental Office, Sendai, Japan. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Makoto Nishimura, Division of Oral Dysfunction Sci- ence, Department of Oral Health and Development Sciences, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan; e-mail, [email protected]. Submitted, January 2012; revised and accepted, June 2012. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2012.06.022 85 CASE REPORT
Nonextraction treatment with temporary skeletal anchorage devices to correct a Class II Division 2 malocclusion with excessive gingival display
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Nonextraction treatment with temporary skeletal anchorage devices to correct a Class II Division 2 malocclusion with excessive gingival displayNonextraction treatment with temporary skeletal anchorage devices to correct a Class II Division 2 malocclusion with excessive gingival display
Makoto Nishimura,a Minayo Sannohe,b Hiroshi Nagasaka,c Kaoru Igarashi,d and Junji Sugawarae
Sendai and Saitama, Japan, and Farmington, Conn
aAssis Denti bPriva cLectu hoku dProfe Tohok eVisiti Scien Conn Senda All au Poten Addre ence, Denti Japan Subm 0889- Copyr http:/
The patient was a 22-year-old Japanese woman who complained of a gummy smile. She had several other or- thodontic problems, including crowding of the maxillary anterior teeth, retroclination of the maxillary central in- cisors, excessive maxillary incisor display, a deep overbite, Class II dental relationships, a Class II profile, and a long face. Two options for the correction of these problems were proposed. The first option was to extract the maxillary first premolars to correct the Class II relationship and implant a miniscrew to correct the gingival display; the second option was to place 2 miniplates for distalization of the maxillary molars and a miniscrew to correct the gingival smile without premolar extractions. The patient chose the second option. After placing a preadjusted bracketed system, 2 miniplates were placed in the zygomatic buttresses bilaterally with monocort- ical screws, and 1miniscrewwas fixed between the root apices of themaxillary central incisors. Distalization and intrusion of the maxillary molars and intrusion of the maxillary incisors were simultaneously started with those temporary skeletal anchorage devices functioning as absolute orthodontic anchors. The total treatment period was approximately 22 months. Her orthodontic problems were corrected. According to the cephalometric eval- uation, the entire maxillary dentition was significantly distalized, and her maxillary incisors were successfully intruded, with the mandible showing a slight counterclockwise rotation. Thanks to the temporary anchorage de- vices combinedwithminiplates and aminiscrew, wewere able to predictably achieve her treatment goals without premolar extractions, orthognathic surgery, and the need for patient compliance. (Am J Orthod Dentofacial Orthop 2014;145:85-94)
The prevalence of Angle Class II Division 2 maloc- clusion is relatively low in comparison with other malocclusions.1-3 This malocclusion is generally
characterized by retroclination of the maxillary incisors, a deepbite, and an obtuse interincisal angle.4
In the treatment of a Class II Division 2 malocclusion,
tant professor, Division of Oral Dysfunction Science, Graduate School of stry, Tohoku University, Sendai, Japan. te practice, Saitama, Japan. rer, Division of Maxillofacial Surgery, Graduate School of Dentistry, To- University, Sendai, Japan. ssor, Division of Oral Dysfunction Science, Graduate School of Dentistry, u University, Sendai, Japan. ng clinical professor, Division of Orthodontics, Department of Craniofacial ce, School of Dental Medicine, University of Connecticut, Farmington, ; chief orthodontist, SAS Orthodontic Centre, Ichiban-cho Dental Office, i, Japan. thors have completed and submitted the ICMJE Form for Disclosure of tial Conflicts of Interest, and none were reported. ss correspondence to: Makoto Nishimura, Division of Oral Dysfunction Sci- Department of Oral Health and Development Sciences, Graduate School of stry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, ; e-mail, [email protected]. itted, January 2012; revised and accepted, June 2012. 5406/$36.00 ight 2014 by the American Association of Orthodontists. /dx.doi.org/10.1016/j.ajodo.2012.06.022
the improvement of a deepbite with a gummy smile is a challenging treatment objective. Conventional ortho- dontic methods, such as an intrusive arch, have been used to reduce overbite, often resulting in undesirable extrusion and flaring of the posterior teeth.5 The clock- wise rotation of the mandible caused by the extrusion of the posterior teeth worsens the Class II convex profile in many patients and also leads to an increase in the inci- dence of relapse for adults.6-10 Extraoral appliances to reduce overbite, such as the J-hook, are effective in controlling the anchorage, but it is difficult to predict the final result in uncooperative patients.11 There is a clear need for a procedure for patients with deepbite and excessive gingival display resulting a gummy smile that effectively intrudes the maxillary incisors without undesirable side effects and without their cooperation.
The successful use of temporary skeletal anchorage devices (TSADs) as absolute anchorage to reduce over- bite in nongrowing patients has been reported.12,13
However, no case report has detailed the simultaneous intrusion of the anterior teeth to correct a gummy smile and distalization of the maxillary posterior teeth to correct molar relationships.
85
86 Nishimura et al
In this case report, we present the nonextraction treatment of an adult with a Class II Division 2 malocclu- sion whose deep overbite and gummy smile were pre- dictably corrected using TSADs combined with miniplates and a miniscrew on the basis of a goal- oriented approach.
DIAGNOSIS AND ETIOLOGY
The patient, a 22-year-old Japanese woman, had a convex profile, a Class II malocclusion, and excessive display of her maxillary incisors (Fig 1). Her chief complaint was a gummy smile. A short upper lip and hy- peractivity of the elevator muscles of the upper lip were found in the clinical examination and are clearly shown in her pretreatment smiling photograph. Intraorally, she had Class II molar relationships bilaterally, a deep over- bite, retroclination of the maxillary incisors, a high canine on the left hand side, and anterior crowding in the maxilla (Fig 2).
The initial lateral cephalometric radiograph was taken in natural head position with relaxed lip posture
January 2014 Vol 145 Issue 1 American
and at centric relation (Fig 3). The cephalometric tem- plate analysis (Fig 4) and the cephalometric measure- ments (Table) clearly indicated that she had a skeletal Class II profile, retroclination of the maxillary central in- cisors, and excessive eruption of the maxillary incisors. The panoramic radiograph showed her bilateral mandib- ular third molars. The level of alveolar bone crest was within the normal range, and she had healthy peri- odontal tissues (Fig 5).
TREATMENT OBJECTIVES
The principal treatment objectives were to achieve optimal overjet and overbite, improve her gummy smile, and establish Class I canine and molar relationships. Figure 6 shows her treatment goal on the basis of the cephalometric prediction. According to her treatment goal, the maxillary central incisors and first molars needed to be intruded by 4.0 and 1.0 mm, respectively. The intru- sion of the entire maxillary dentition was expected to induce a counterclockwise rotation of themandible, in ef- fect improving her Class II profile and significantly
Journal of Orthodontics and Dentofacial Orthopedics
Fig 2. Pretreatment dental models.
Fig 3. Pretreatment cephalometric radiograph.
Nishimura et al 87
reducing her large interlabial gap. In addition, a 4.0-mm average bilateral distalization of the maxillary molars was needed to correct her Class II dentition.
American Journal of Orthodontics and Dentofacial Orthoped
TREATMENT ALTERNATIVES
The development of TSADs has made it possible to correct a gummy smile successfully without surgery. Orthognathic surgery is no longer the first option for the correction of a gummy smile. The patient was given 2 nonsurgical alternatives: the first option was to extract the maxillary first premolars for Class II correc- tion and implant a miniscrew for gummy simile correc- tion, and the second option was to place 2 miniplates for distalization of the maxillary molars and a mini- screw for gummy smile correction without premolar extractions.
Since she was reluctant to have her 2 maxillary pre- molars extracted, she decided on the second option.
TREATMENT PROGRESS
Before starting the orthodontic treatment, the bilat- eral mandibular third molars were extracted. Subse- quently, 0.022-in preadjusted brackets were bonded at the maxillary posterior teeth, nickel-titanium archwires were engaged for leveling and aligning segmentally, and titaniumminiplates (Dentsply Sankin, Tokyo, Japan) were implanted at the zygomatic buttresses bilaterally under local anesthesia by an oral surgeon. A 0.032 3 0.032-in transpalatal arch was placed to prevent buccal expansion of the first premolars after distalization of the maxillary posterior teeth and buccal flaring of the molars during intrusion of the maxillary molars.
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Fig 4. Craniofacial drawing standards analysis.
Table. Cephalometric analysis
Pretreatment Posttreatment Retention
2 y Norm SNA () 76 75 75 82 SNB () 69 69 69 80.5 ANB () 7 6 6 1.5 AB to occlusal plane (mm)
4 3 4 -
U1 to SN () 77.5 94 90.5 107.5 SN-OP () 27 25 24 16 FMA () 35.5 35 35 29 IMPA () 91 96 97 96.5 FMIA () 53.5 49 47 54.5 Interincisal angle () 145.5 124 126 127 Upper lip (mm) 0 1 1 1 Lower lip (mm) 1 0 0.5 0
Fig 5. Pretreatment panoramic radiograph.
Fig 6. Treatment goal.
88 Nishimura et al
Three weeks after the implantation surgery, distaliza- tion of the maxillary posterior segments was started with elastic chain modules. The magnitude of orthodontic force for distalization was 250 g per side. During
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distalization of the maxillary posterior segments, the buccal archwires were ligated to the transpalatal arch at the maxillary first premolar to prevent expansion of the first premolar (Figs 7, A, 8, A, and 9, A).
Four months later, brackets were bonded at the maxillary anterior dentition, and a miniscrew was fixed between the root apices of the maxillary central incisors. Thereafter, leveling and aligning of the entire maxillary dentition and intrusion of the maxillary incisors were started by applying an elastic thread tied from the head of the miniscrew to the archwire between the maxillary central incisors (Figs 7, B; and 8, B). Then, after engaging a rigid rectangular wire (0.0175 3 0.025-in stainless steel), distalization of the entire maxillary dentition was started. Orthodontic force was delivered from the miniplates to the power arms that were placed between the maxillary canines and first pre- molars (Figs 7, C, 8, C, and 9, B).
Ten months later, brackets were bonded on the entire mandibular dentition, and leveling and aligning were initiated with a nickel-titanium archwire. The intrusion of the entire maxillary arch started with the application
Journal of Orthodontics and Dentofacial Orthopedics
Fig 7. A-F, Treatment progress intraoral photographs, frontal view.
Fig 8. A-F, Treatment progress intraoral photographs, lateral view.
Fig 9. A-C, TSAD mechanics for distalization of molars and intrusion of incisors and maxillary dentition.
Nishimura et al 89
of specific mechanics. The maxillary incisors were intruded using a miniscrew, and the canines and premo- lars were intruded by intrusion cantilevers. Those levers
American Journal of Orthodontics and Dentofacial Orthoped
were inserted into the buccal tubes bonded on the head portion of the miniplates. In addition, another intrusive force was bilaterally applied with elastic threads
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Fig 10. Posttreatment facial and intraoral photographs.
Fig 11. Posttreatment dental models.
90 Nishimura et al
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Fig 12. Posttreatment cephalometric radiograph.
Fig 13. Posttreatment cephalometric superimposition.
Fig 14. Posttreatment panoramic radiograph.
Nishimura et al 91
from the miniplates to the maxillary first molars at the same time (Figs 7, D, 8, D, and 9, C).
After intrusion of the maxillary dentition, distaliza- tion of the entire maxillary dentition was carried out to
American Journal of Orthodontics and Dentofacial Orthoped
correct the molar relationships and overjet (Figs 7, E, and 8, E). Through the finishing and detailing stage, a functional occlusion with proper anterior guidance and rigid posterior support was established (Figs 7, F, and 8, F). Since the clinical crown length of the maxillary incisors was reduced by the intrusion, electrical cautery was used to modify the gingival margins of the maxillary incisors once the intrusion was completed.
After 22 months of active orthodontic treatment, the multibracketed system and all the TSADs were removed. Immediately after debonding, a wraparound type of retainer in the maxillary dentition and a lingual bonded retainer from canine to canine in the mandibular denti- tion were placed.
TREATMENT RESULTS
Thanks to the application of the 2 types of TSADs, the patient's orthodontic problems dramatically improved. She obtained a balanced profile, and her gummy smile and deepbite were dramatically corrected. The canine and molar relationships were normalized from Class II to Class I. A functional occlusion with stable posterior support and proper anterior guidance was established (Figs 10 and 11).
The cephalometric superimposition before and after treatment showed that her treatment goals were predict- ably achieved (Figs 12 and 13). Particularly worthy of note is the accuracy of the results of the maxillary inci- sors and molar positions: these were almost exactly the same as the treatment goals. The maxillary first molars were intruded about 1.5 mm and distalized by 4.0 mm. The maxillary central incisors were intruded by 3.5 mm. The amount of counterclockwise rotation of the mandible was less than predicted. The panoramic radiograph taken at debonding showed that her maxil- lary and mandibular dentitions had proper root paral- lelism (Fig 14). A stable occlusion and a balanced profile have been maintained during the 2-year follow- up period (Figs 15 and 16).
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Fig 15. Two-year posttreatment facial and intraoral photographs.
Fig 16. Two-year posttreatment panoramic radiograph.
92 Nishimura et al
DISCUSSION
A gummy smile is the result of a combination of fac- tors, including excessive eruption of the maxillary inci- sors, vertical maxillary excess including a posterior gummy smile, a short upper lip, and hyperactivity of the elevator muscles of the upper lip.14,15 The principal factor in this patient seemed to be the excessive eruption of the maxillary incisors (central incisors to stomion, 8.0 mm). Thus, we believed that if the
January 2014 Vol 145 Issue 1 American
extruded maxillary incisors were intruded, the gummy smile would be improved after the remodeling of the alveolar bone and the gingivae of the incisors.
Creekmore and Eklund12 were the first to report intrusion of the maxillary incisors with a TSAD when they used a surgical vitallium bone screw. Ohnishi et al13 reported maxillary incisor intrusion using a mini- screw. Clearly, TSADs can intrude the maxillary incisors without side effects: ie, without extrusion of the maxil- lary molars or the undesirable clockwise rotation of the mandible. Recently, Lin et al16 reported simultaneous reduction in the vertical dimension and improvement of a gummy smile using miniscrews. Especially in nongrowing patients, intrusion mechanics with TSADs are the most effective and useful method available to us at this time and compare favorably with conventional orthodontic therapies.
In our patient, the maxillary incisors were success- fully intruded by 3.5 mm, and the gummy smile improved without side effects. The maxillary molars were intruded by 1.5 mm. In addition, the intruded incisors and molars showed no relapse at the 2-year
Journal of Orthodontics and Dentofacial Orthopedics
Nishimura et al 93
follow-up. Riedel17 suggested that a large interincisal angle at the end of treatment was associated with relapse of a deepbite. The patient's interincisal angle was reduced by 21.5 during orthodontic treatment. Ac- cording to the literature to date, the relapse rates after maxillary molar intrusion and maxillary incisor intrusion range from 10% to 30%18-20 and 20% to 60%,21-26
respectively. These authors also reported that intruded molars are less stable than are mesiodistal movement and rotation because no effective method for retention has been developed. It has been suggested that intrusion should be performed slowly to allow for neuromuscular adaptation, overcorrection, and active retention, and that this strategy will assist in stabilizing the intrusive molars.17,20
After distalization of the maxillary molars, the Class II molar relationship was successfully corrected in this pa- tient. It has been reported that the average amount of distalization of the maxillary first molars with miniplates is 3.8 mm at the crown level.27 In this patient, distaliza- tion of the maxillary first molar was 4.0 mm. The maxil- lary molars were predictably distalized in accordance with the treatment goals established before the ortho- dontic treatment. The biomechanics of the skeletal anchorage system with miniplates for distalization are simpler than those for miniscrews because miniplates are fixed outside the dentition. Since miniplates do not disturb tooth movement in any way, the skeletal anchorage system makes simultaneous 3-dimensional control of the maxillary and mandibular teeth possible. Since the miniplate is one of the most reliable TSADs, the treatment goal can be predictably achieved, with lit- tle difference between the objectives established before treatment and the outcome of treatment.
For the bodily distalization of the posterior teeth, lever arms were extended from the main arch to bring the line of force closer to the center of resistance, in effect limiting the length of the lever arm because of the soft-tissue impingement. In this patient, the line of orthodontic force was expected to be below the center of resistance of the whole maxillary dentition. As a result, it was expected that extrusion of the anterior teeth and intrusion of the posterior teeth would induce clockwise rotation of the occlusal plane. Extrusion of the anterior teeth was considered particularly undesir- able because it would only worsen the gummy smile. The miniscrew implanted between the root apices of the maxillary central incisors and the intruding lever arm were required for prevention of undesirable side ef- fects that are sometimes associated with distalization of the posterior teeth and correction of a gummy smile. Because the surgical intervention required for the inser- tion of a miniscrew is relatively minor and because it is
American Journal of Orthodontics and Dentofacial Orthoped
possible to intrude the anterior teeth without undesir- able side effects with a miniscrew, a miniscrew is consid- ered to provide the most effective mechanism to predictably intrude the anterior teeth.
In an orthodontic treatment that requires distaliza- tion to correct the molar relationships and intrusion to correct a gummy smile, it is possible to predictably achieve treatment goals using a combination of TSADs: miniplates and a miniscrew.
CONCLUSIONS
Thanks to a combination of TSADs, miniplates, and a miniscrew, the correction of this patient's Class II Division 2 malocclusion with a gummy smile was suc- cessfully achieved without premolar extractions, or- thognathic surgery, and the need for patient compliance.
REFERENCES
1. Massler M, Frankel JM. Prevalence of malocclusion in children aged 14 to 18 years. Am J Orthod 1951;37:751-68.
2. Ast DH, Carios AP, Cons NC. The prevalence and characteristics of malocclusion among senior high school students in upstate New York. Am J Orthod 1965;51:437-45.
3. Peck S, Peck L, Kataja M. Class II Division 2 malocclusion: a heri- table pattern of small teeth in well-developed jaws. Angle Orthod 1998;68:9-20.
4. Brezniak N, Arad A, Heller M, Dinbar A, Dinte A, Wasserstein A. Pathognomonic cephalometric characteristics of Angle Class II Di- vision 2 malocclusion. Angle Orthod 2002;72:251-7.
5. Burstone CJ. Deep overbite correction by intrusion. Am J Orthod 1977;72:1-22.
6. Bell WH, Jacobs JD, Legan HL. Treatment of Class II deep bite by orthodontic and surgical means. Am J Orthod 1984;85:1-20.
7. Wylie WL. Overbite and vertical facial dimensions in terms of mus- cle balance. Angle Orthod 1944;14:13-7.
8. Schudy FF. The association of anatomical entities as applied to clinical orthodontics. Angle Orthod 1966;36:190-203.
9. MacDowell EH, Baker IM. The skeletodental adaptations in deep bite correction. Am J Orthod Dentofacial Orthop 1991;100: 370-5.
10. Bench RW, Gugino CF, Hilgers JJ. Bio-progressive therapy. Part 2. J Clin Orthod 1977;11:661-82.
11. Janzen EK. A balanced smile—a most important treatment objec- tive. Am J Orthod 1977;72:359-72.
12. Creekmore TD, Eklund MK. The possibility of skeletal anchorage. J Clin Orthod 1983;17:266-9.
13. Ohnishi H, Yagi T, Yasuda Y, Takata K. A mini-implant for ortho- dontic anchorage in a deep overbite case. Angle Orthod 2005;75: 444-52.
14. Monaco A, Streni O, Marci MC, Marzo G, Gatto R, Giannoni M. Gummy smile: clinical parameters useful for diagnosis and thera- peutical approach. J Clin Pediatr Dent 2004;29:19-25.
15. Robbins JW. Differential diagnosis and treatment of excess gingival display. Pract Periodontics Aesthet Dent 1999;11:265-72.
16. Lin JC, Liou EJ, Bowman SJ. Simultaneous reduction in vertical dimension and gummy…
Makoto Nishimura,a Minayo Sannohe,b Hiroshi Nagasaka,c Kaoru Igarashi,d and Junji Sugawarae
Sendai and Saitama, Japan, and Farmington, Conn
aAssis Denti bPriva cLectu hoku dProfe Tohok eVisiti Scien Conn Senda All au Poten Addre ence, Denti Japan Subm 0889- Copyr http:/
The patient was a 22-year-old Japanese woman who complained of a gummy smile. She had several other or- thodontic problems, including crowding of the maxillary anterior teeth, retroclination of the maxillary central in- cisors, excessive maxillary incisor display, a deep overbite, Class II dental relationships, a Class II profile, and a long face. Two options for the correction of these problems were proposed. The first option was to extract the maxillary first premolars to correct the Class II relationship and implant a miniscrew to correct the gingival display; the second option was to place 2 miniplates for distalization of the maxillary molars and a miniscrew to correct the gingival smile without premolar extractions. The patient chose the second option. After placing a preadjusted bracketed system, 2 miniplates were placed in the zygomatic buttresses bilaterally with monocort- ical screws, and 1miniscrewwas fixed between the root apices of themaxillary central incisors. Distalization and intrusion of the maxillary molars and intrusion of the maxillary incisors were simultaneously started with those temporary skeletal anchorage devices functioning as absolute orthodontic anchors. The total treatment period was approximately 22 months. Her orthodontic problems were corrected. According to the cephalometric eval- uation, the entire maxillary dentition was significantly distalized, and her maxillary incisors were successfully intruded, with the mandible showing a slight counterclockwise rotation. Thanks to the temporary anchorage de- vices combinedwithminiplates and aminiscrew, wewere able to predictably achieve her treatment goals without premolar extractions, orthognathic surgery, and the need for patient compliance. (Am J Orthod Dentofacial Orthop 2014;145:85-94)
The prevalence of Angle Class II Division 2 maloc- clusion is relatively low in comparison with other malocclusions.1-3 This malocclusion is generally
characterized by retroclination of the maxillary incisors, a deepbite, and an obtuse interincisal angle.4
In the treatment of a Class II Division 2 malocclusion,
tant professor, Division of Oral Dysfunction Science, Graduate School of stry, Tohoku University, Sendai, Japan. te practice, Saitama, Japan. rer, Division of Maxillofacial Surgery, Graduate School of Dentistry, To- University, Sendai, Japan. ssor, Division of Oral Dysfunction Science, Graduate School of Dentistry, u University, Sendai, Japan. ng clinical professor, Division of Orthodontics, Department of Craniofacial ce, School of Dental Medicine, University of Connecticut, Farmington, ; chief orthodontist, SAS Orthodontic Centre, Ichiban-cho Dental Office, i, Japan. thors have completed and submitted the ICMJE Form for Disclosure of tial Conflicts of Interest, and none were reported. ss correspondence to: Makoto Nishimura, Division of Oral Dysfunction Sci- Department of Oral Health and Development Sciences, Graduate School of stry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, ; e-mail, [email protected]. itted, January 2012; revised and accepted, June 2012. 5406/$36.00 ight 2014 by the American Association of Orthodontists. /dx.doi.org/10.1016/j.ajodo.2012.06.022
the improvement of a deepbite with a gummy smile is a challenging treatment objective. Conventional ortho- dontic methods, such as an intrusive arch, have been used to reduce overbite, often resulting in undesirable extrusion and flaring of the posterior teeth.5 The clock- wise rotation of the mandible caused by the extrusion of the posterior teeth worsens the Class II convex profile in many patients and also leads to an increase in the inci- dence of relapse for adults.6-10 Extraoral appliances to reduce overbite, such as the J-hook, are effective in controlling the anchorage, but it is difficult to predict the final result in uncooperative patients.11 There is a clear need for a procedure for patients with deepbite and excessive gingival display resulting a gummy smile that effectively intrudes the maxillary incisors without undesirable side effects and without their cooperation.
The successful use of temporary skeletal anchorage devices (TSADs) as absolute anchorage to reduce over- bite in nongrowing patients has been reported.12,13
However, no case report has detailed the simultaneous intrusion of the anterior teeth to correct a gummy smile and distalization of the maxillary posterior teeth to correct molar relationships.
85
86 Nishimura et al
In this case report, we present the nonextraction treatment of an adult with a Class II Division 2 malocclu- sion whose deep overbite and gummy smile were pre- dictably corrected using TSADs combined with miniplates and a miniscrew on the basis of a goal- oriented approach.
DIAGNOSIS AND ETIOLOGY
The patient, a 22-year-old Japanese woman, had a convex profile, a Class II malocclusion, and excessive display of her maxillary incisors (Fig 1). Her chief complaint was a gummy smile. A short upper lip and hy- peractivity of the elevator muscles of the upper lip were found in the clinical examination and are clearly shown in her pretreatment smiling photograph. Intraorally, she had Class II molar relationships bilaterally, a deep over- bite, retroclination of the maxillary incisors, a high canine on the left hand side, and anterior crowding in the maxilla (Fig 2).
The initial lateral cephalometric radiograph was taken in natural head position with relaxed lip posture
January 2014 Vol 145 Issue 1 American
and at centric relation (Fig 3). The cephalometric tem- plate analysis (Fig 4) and the cephalometric measure- ments (Table) clearly indicated that she had a skeletal Class II profile, retroclination of the maxillary central in- cisors, and excessive eruption of the maxillary incisors. The panoramic radiograph showed her bilateral mandib- ular third molars. The level of alveolar bone crest was within the normal range, and she had healthy peri- odontal tissues (Fig 5).
TREATMENT OBJECTIVES
The principal treatment objectives were to achieve optimal overjet and overbite, improve her gummy smile, and establish Class I canine and molar relationships. Figure 6 shows her treatment goal on the basis of the cephalometric prediction. According to her treatment goal, the maxillary central incisors and first molars needed to be intruded by 4.0 and 1.0 mm, respectively. The intru- sion of the entire maxillary dentition was expected to induce a counterclockwise rotation of themandible, in ef- fect improving her Class II profile and significantly
Journal of Orthodontics and Dentofacial Orthopedics
Fig 2. Pretreatment dental models.
Fig 3. Pretreatment cephalometric radiograph.
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reducing her large interlabial gap. In addition, a 4.0-mm average bilateral distalization of the maxillary molars was needed to correct her Class II dentition.
American Journal of Orthodontics and Dentofacial Orthoped
TREATMENT ALTERNATIVES
The development of TSADs has made it possible to correct a gummy smile successfully without surgery. Orthognathic surgery is no longer the first option for the correction of a gummy smile. The patient was given 2 nonsurgical alternatives: the first option was to extract the maxillary first premolars for Class II correc- tion and implant a miniscrew for gummy simile correc- tion, and the second option was to place 2 miniplates for distalization of the maxillary molars and a mini- screw for gummy smile correction without premolar extractions.
Since she was reluctant to have her 2 maxillary pre- molars extracted, she decided on the second option.
TREATMENT PROGRESS
Before starting the orthodontic treatment, the bilat- eral mandibular third molars were extracted. Subse- quently, 0.022-in preadjusted brackets were bonded at the maxillary posterior teeth, nickel-titanium archwires were engaged for leveling and aligning segmentally, and titaniumminiplates (Dentsply Sankin, Tokyo, Japan) were implanted at the zygomatic buttresses bilaterally under local anesthesia by an oral surgeon. A 0.032 3 0.032-in transpalatal arch was placed to prevent buccal expansion of the first premolars after distalization of the maxillary posterior teeth and buccal flaring of the molars during intrusion of the maxillary molars.
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Fig 4. Craniofacial drawing standards analysis.
Table. Cephalometric analysis
Pretreatment Posttreatment Retention
2 y Norm SNA () 76 75 75 82 SNB () 69 69 69 80.5 ANB () 7 6 6 1.5 AB to occlusal plane (mm)
4 3 4 -
U1 to SN () 77.5 94 90.5 107.5 SN-OP () 27 25 24 16 FMA () 35.5 35 35 29 IMPA () 91 96 97 96.5 FMIA () 53.5 49 47 54.5 Interincisal angle () 145.5 124 126 127 Upper lip (mm) 0 1 1 1 Lower lip (mm) 1 0 0.5 0
Fig 5. Pretreatment panoramic radiograph.
Fig 6. Treatment goal.
88 Nishimura et al
Three weeks after the implantation surgery, distaliza- tion of the maxillary posterior segments was started with elastic chain modules. The magnitude of orthodontic force for distalization was 250 g per side. During
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distalization of the maxillary posterior segments, the buccal archwires were ligated to the transpalatal arch at the maxillary first premolar to prevent expansion of the first premolar (Figs 7, A, 8, A, and 9, A).
Four months later, brackets were bonded at the maxillary anterior dentition, and a miniscrew was fixed between the root apices of the maxillary central incisors. Thereafter, leveling and aligning of the entire maxillary dentition and intrusion of the maxillary incisors were started by applying an elastic thread tied from the head of the miniscrew to the archwire between the maxillary central incisors (Figs 7, B; and 8, B). Then, after engaging a rigid rectangular wire (0.0175 3 0.025-in stainless steel), distalization of the entire maxillary dentition was started. Orthodontic force was delivered from the miniplates to the power arms that were placed between the maxillary canines and first pre- molars (Figs 7, C, 8, C, and 9, B).
Ten months later, brackets were bonded on the entire mandibular dentition, and leveling and aligning were initiated with a nickel-titanium archwire. The intrusion of the entire maxillary arch started with the application
Journal of Orthodontics and Dentofacial Orthopedics
Fig 7. A-F, Treatment progress intraoral photographs, frontal view.
Fig 8. A-F, Treatment progress intraoral photographs, lateral view.
Fig 9. A-C, TSAD mechanics for distalization of molars and intrusion of incisors and maxillary dentition.
Nishimura et al 89
of specific mechanics. The maxillary incisors were intruded using a miniscrew, and the canines and premo- lars were intruded by intrusion cantilevers. Those levers
American Journal of Orthodontics and Dentofacial Orthoped
were inserted into the buccal tubes bonded on the head portion of the miniplates. In addition, another intrusive force was bilaterally applied with elastic threads
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Fig 10. Posttreatment facial and intraoral photographs.
Fig 11. Posttreatment dental models.
90 Nishimura et al
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Fig 12. Posttreatment cephalometric radiograph.
Fig 13. Posttreatment cephalometric superimposition.
Fig 14. Posttreatment panoramic radiograph.
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from the miniplates to the maxillary first molars at the same time (Figs 7, D, 8, D, and 9, C).
After intrusion of the maxillary dentition, distaliza- tion of the entire maxillary dentition was carried out to
American Journal of Orthodontics and Dentofacial Orthoped
correct the molar relationships and overjet (Figs 7, E, and 8, E). Through the finishing and detailing stage, a functional occlusion with proper anterior guidance and rigid posterior support was established (Figs 7, F, and 8, F). Since the clinical crown length of the maxillary incisors was reduced by the intrusion, electrical cautery was used to modify the gingival margins of the maxillary incisors once the intrusion was completed.
After 22 months of active orthodontic treatment, the multibracketed system and all the TSADs were removed. Immediately after debonding, a wraparound type of retainer in the maxillary dentition and a lingual bonded retainer from canine to canine in the mandibular denti- tion were placed.
TREATMENT RESULTS
Thanks to the application of the 2 types of TSADs, the patient's orthodontic problems dramatically improved. She obtained a balanced profile, and her gummy smile and deepbite were dramatically corrected. The canine and molar relationships were normalized from Class II to Class I. A functional occlusion with stable posterior support and proper anterior guidance was established (Figs 10 and 11).
The cephalometric superimposition before and after treatment showed that her treatment goals were predict- ably achieved (Figs 12 and 13). Particularly worthy of note is the accuracy of the results of the maxillary inci- sors and molar positions: these were almost exactly the same as the treatment goals. The maxillary first molars were intruded about 1.5 mm and distalized by 4.0 mm. The maxillary central incisors were intruded by 3.5 mm. The amount of counterclockwise rotation of the mandible was less than predicted. The panoramic radiograph taken at debonding showed that her maxil- lary and mandibular dentitions had proper root paral- lelism (Fig 14). A stable occlusion and a balanced profile have been maintained during the 2-year follow- up period (Figs 15 and 16).
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Fig 15. Two-year posttreatment facial and intraoral photographs.
Fig 16. Two-year posttreatment panoramic radiograph.
92 Nishimura et al
DISCUSSION
A gummy smile is the result of a combination of fac- tors, including excessive eruption of the maxillary inci- sors, vertical maxillary excess including a posterior gummy smile, a short upper lip, and hyperactivity of the elevator muscles of the upper lip.14,15 The principal factor in this patient seemed to be the excessive eruption of the maxillary incisors (central incisors to stomion, 8.0 mm). Thus, we believed that if the
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extruded maxillary incisors were intruded, the gummy smile would be improved after the remodeling of the alveolar bone and the gingivae of the incisors.
Creekmore and Eklund12 were the first to report intrusion of the maxillary incisors with a TSAD when they used a surgical vitallium bone screw. Ohnishi et al13 reported maxillary incisor intrusion using a mini- screw. Clearly, TSADs can intrude the maxillary incisors without side effects: ie, without extrusion of the maxil- lary molars or the undesirable clockwise rotation of the mandible. Recently, Lin et al16 reported simultaneous reduction in the vertical dimension and improvement of a gummy smile using miniscrews. Especially in nongrowing patients, intrusion mechanics with TSADs are the most effective and useful method available to us at this time and compare favorably with conventional orthodontic therapies.
In our patient, the maxillary incisors were success- fully intruded by 3.5 mm, and the gummy smile improved without side effects. The maxillary molars were intruded by 1.5 mm. In addition, the intruded incisors and molars showed no relapse at the 2-year
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follow-up. Riedel17 suggested that a large interincisal angle at the end of treatment was associated with relapse of a deepbite. The patient's interincisal angle was reduced by 21.5 during orthodontic treatment. Ac- cording to the literature to date, the relapse rates after maxillary molar intrusion and maxillary incisor intrusion range from 10% to 30%18-20 and 20% to 60%,21-26
respectively. These authors also reported that intruded molars are less stable than are mesiodistal movement and rotation because no effective method for retention has been developed. It has been suggested that intrusion should be performed slowly to allow for neuromuscular adaptation, overcorrection, and active retention, and that this strategy will assist in stabilizing the intrusive molars.17,20
After distalization of the maxillary molars, the Class II molar relationship was successfully corrected in this pa- tient. It has been reported that the average amount of distalization of the maxillary first molars with miniplates is 3.8 mm at the crown level.27 In this patient, distaliza- tion of the maxillary first molar was 4.0 mm. The maxil- lary molars were predictably distalized in accordance with the treatment goals established before the ortho- dontic treatment. The biomechanics of the skeletal anchorage system with miniplates for distalization are simpler than those for miniscrews because miniplates are fixed outside the dentition. Since miniplates do not disturb tooth movement in any way, the skeletal anchorage system makes simultaneous 3-dimensional control of the maxillary and mandibular teeth possible. Since the miniplate is one of the most reliable TSADs, the treatment goal can be predictably achieved, with lit- tle difference between the objectives established before treatment and the outcome of treatment.
For the bodily distalization of the posterior teeth, lever arms were extended from the main arch to bring the line of force closer to the center of resistance, in effect limiting the length of the lever arm because of the soft-tissue impingement. In this patient, the line of orthodontic force was expected to be below the center of resistance of the whole maxillary dentition. As a result, it was expected that extrusion of the anterior teeth and intrusion of the posterior teeth would induce clockwise rotation of the occlusal plane. Extrusion of the anterior teeth was considered particularly undesir- able because it would only worsen the gummy smile. The miniscrew implanted between the root apices of the maxillary central incisors and the intruding lever arm were required for prevention of undesirable side ef- fects that are sometimes associated with distalization of the posterior teeth and correction of a gummy smile. Because the surgical intervention required for the inser- tion of a miniscrew is relatively minor and because it is
American Journal of Orthodontics and Dentofacial Orthoped
possible to intrude the anterior teeth without undesir- able side effects with a miniscrew, a miniscrew is consid- ered to provide the most effective mechanism to predictably intrude the anterior teeth.
In an orthodontic treatment that requires distaliza- tion to correct the molar relationships and intrusion to correct a gummy smile, it is possible to predictably achieve treatment goals using a combination of TSADs: miniplates and a miniscrew.
CONCLUSIONS
Thanks to a combination of TSADs, miniplates, and a miniscrew, the correction of this patient's Class II Division 2 malocclusion with a gummy smile was suc- cessfully achieved without premolar extractions, or- thognathic surgery, and the need for patient compliance.
REFERENCES
1. Massler M, Frankel JM. Prevalence of malocclusion in children aged 14 to 18 years. Am J Orthod 1951;37:751-68.
2. Ast DH, Carios AP, Cons NC. The prevalence and characteristics of malocclusion among senior high school students in upstate New York. Am J Orthod 1965;51:437-45.
3. Peck S, Peck L, Kataja M. Class II Division 2 malocclusion: a heri- table pattern of small teeth in well-developed jaws. Angle Orthod 1998;68:9-20.
4. Brezniak N, Arad A, Heller M, Dinbar A, Dinte A, Wasserstein A. Pathognomonic cephalometric characteristics of Angle Class II Di- vision 2 malocclusion. Angle Orthod 2002;72:251-7.
5. Burstone CJ. Deep overbite correction by intrusion. Am J Orthod 1977;72:1-22.
6. Bell WH, Jacobs JD, Legan HL. Treatment of Class II deep bite by orthodontic and surgical means. Am J Orthod 1984;85:1-20.
7. Wylie WL. Overbite and vertical facial dimensions in terms of mus- cle balance. Angle Orthod 1944;14:13-7.
8. Schudy FF. The association of anatomical entities as applied to clinical orthodontics. Angle Orthod 1966;36:190-203.
9. MacDowell EH, Baker IM. The skeletodental adaptations in deep bite correction. Am J Orthod Dentofacial Orthop 1991;100: 370-5.
10. Bench RW, Gugino CF, Hilgers JJ. Bio-progressive therapy. Part 2. J Clin Orthod 1977;11:661-82.
11. Janzen EK. A balanced smile—a most important treatment objec- tive. Am J Orthod 1977;72:359-72.
12. Creekmore TD, Eklund MK. The possibility of skeletal anchorage. J Clin Orthod 1983;17:266-9.
13. Ohnishi H, Yagi T, Yasuda Y, Takata K. A mini-implant for ortho- dontic anchorage in a deep overbite case. Angle Orthod 2005;75: 444-52.
14. Monaco A, Streni O, Marci MC, Marzo G, Gatto R, Giannoni M. Gummy smile: clinical parameters useful for diagnosis and thera- peutical approach. J Clin Pediatr Dent 2004;29:19-25.
15. Robbins JW. Differential diagnosis and treatment of excess gingival display. Pract Periodontics Aesthet Dent 1999;11:265-72.
16. Lin JC, Liou EJ, Bowman SJ. Simultaneous reduction in vertical dimension and gummy…
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