CASE REPORT
Orthodontic decompensation and correction of skeletal Class III malocclusion with gradual dentoalveolar remodeling in a growing patient Bin Cai,a Xiao-Guang Zhao,b and Lu-Sai Xiangc Guangzhou, Guangdong, China
An 8-year-old girl with a skeletal Class III malocclusion was treated in 2 phases. Maxillary expansion and protraction were carried out as the early intervention. However, her maxillary hypoplasia and mandibular hyperplasia deteriorated with age. The phase 2 comprehensive treatment began with proper mechanics when she was 12 years old with growth potential. In the maxillary arch, an auxiliary rectangular wire was used with a round main wire and an opening spring to create space for the impacted teeth and to bodily move the anterior teeth forward. Decompensation of mandibular incisors and correction of the Class III malocclusion were achieved by short Class III elastics with light forces and a gentle interaction between the rectangular wires and the lingual roottorque slots. The phase 2 active treatment period was 4 years 8 months. The 2-year follow-up indicated that our treatment results were quite stable. (Am J Orthod Dentofacial Orthop 2014;145:367-80)
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n the treatment of skeletal Class III malocclusion, there is no clear borderline between what can be achieved by orthodontic camouflage and what inevitably requires orthognathic surgery. Comparatively, orthognathic surgery could obtain substantial skeletal improvement as well as favorable tooth inclinations by the presurgical decompensation. However, camouflage treatment demands more time and high patient compliance, although the treatment expenses and risks are lower.1 For patients who do not want the risk of surgery, early orthodontic intervention in the mixed dentition followed by comprehensive treatment in the early permanent dentition is a valid therapy.2,3 Traditional orthodontic camouflage of skeletal Class III malocclusion always results in more lingual inclination of the mandibular incisors and more proclination of the maxillary incisors for compensation of a skeletal discrepancy.4 However, excessive inclination of the incisors will not only ruin the dental esthetics but also From the Department of Orthodontics, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China. a Associate professor. b Lecturer. c Postgraduate student. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Xiao-Guang Zhao, Department of Orthodontics, Hospital of Stomatology, Sun Yat-sen University, 56 Lingyuan West Rd, Guangzhou, Guangdong, China 510055; e-mail, [email protected]. Submitted, revised and accepted, April 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.04.026
harm the surrounding periodontal tissues, probably from the traumatic occlusal forces.5,6 Authors of a previous study attempted to improve the compensative inclination of the mandibular incisors with mandibular skeletal anchorage.7 The patient's pubertal growth is the optimal timing for routine orthodontic treatment because modifications of dentoalveolar bone are easier in this stage. In general, bone around the alveolar socket will remodel to the some extent after orthodontic tooth movement.8,9 If orthodontists could take the advantage of this period to achieve “orthodontic decompensation” and to correct a Class III malocclusion at the same time by gradual alveolar remodeling with comprehensive orthodontic treatment, further inclination of the incisors and unfavorable side effects could be avoided. How much could the dentoalveolar remodeling compensate for the base bone discrepancy? To answer this question, we present a skeletal Class III patient treated with early intervention and orthodontic camouflage. In her comprehensive orthodontic treatment, we attempted to decompensate the incisor inclination during her growing stage with dentoaveolar remodeling. DIAGNOSIS AND ETIOLOGY
An 8-year-old girl came for orthodontic consultation with chief complaints of an anterior crossbite and a dished-in face. Her parents said that her psychology was negatively affected by her unesthetic facial 367
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appearance. Her medical history showed no systemic diseases or developmental anomalies. Her parents did not have Class III characteristics. The patient had a retrognathic maxilla and a prognathic mandible with a sharp nasolabial angle and a concave facial profile (Fig 1). As shown by the cephalometric analysis, the ANB angle was 3.5 , and the Wits appraisal was 6.5 mm (Fig 2, Table). The intraoral examination indicated a Class III malocclusion with an anterior crossbite and a unilateral crossbite. Cephalometrically, she had lingually inclined mandibular deciduous incisors (Md 1 to MP, 66.8 ) and an excessive interincisal angle (166.1 ), which was the dental compensation of the skeletal Class III discrepancy. Her cephalogram showed that the lower border of the second through the fourth cervical vertebrae had no concavity, indicating that she was at cervical vertebral stage 1.10 Considering the severity of her skeletal problem, we explained the possibility of orthognathic surgery to the patient and her parents. However, they were reluctant to undertake the risks of surgery. TREATMENT OBJECTIVES
The proposed treatment included 2 phases: early orthopedic intervention and comprehensive treatment. Skeletally, we proposed to promote sagittal growth of the maxilla before her pubertal growth spurt to improve the midfacial deficiency and to eliminate the acute nasolabial angle; this could be done in the first stage. Meanwhile, the transverse coordination of the maxilla and the mandible could be carried out by maxillary disjunction with a palatal expander. Since it is impossible to limit the absolute growth of mandible, changing the growth direction could be helpful in the improvement of her skeletal discrepancy. However, we did not expect to increase her facial height much because it would ruin her facial balance. If her mandibular growth exceeded the maxillary growth too much, orthognathic surgery could not be avoided. We explained this to the patient and her parents before the treatment started. Because the patient was reluctant to have surgery, dental camouflage became the solution to compensate for the skeletal discrepancy. The goals consisted of achieving good dental alignment and establishing posterior interdigitation with Class I molar and canine relationships. In addition, to obtain better facial esthetics and more stability, we attempted to decompensate the inclination of the maxillary and mandibular incisors by dentoaveolar remodeling in her phase 2 treatment.
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TREATMENT ALTERNATIVES
Since the patient and her parents cared about her facial appearance, an early intervention of the skeletal discrepancy would benefit her psychological health and make the following treatment easier as well.2,3 Therefore, a plan of 2-phase treatment was made for her. In phase 1 of the treatment, facemask protraction and chincap were 2 alternatives to improve the patient's facial appearance. Because she had a posterior crossbite, maxillary retrognathism, and mandibular prognathism, the maxillary expander with facemask protraction was adopted. In the pretreatment cephalogram, her cervical vertebral maturation was judged to be at least 2 years before the pubertal growth spurt (stage 1); this was good timing for facemask protraction.10 There are different types of expanders including hyrax, Haas, and bonded expanders. Because the maxillary first molars had not erupted yet, a bonded expander was the choice for better retention. Phase 2 treatment would depend on mandibular growth and the patient's preference. Orthognathic surgery is a viable, and even optimal, option especially for a severe skeletal discrepancy.11 It could correct not only the dental problems but also the skeletal and soft tissue discrepancies. However, the patient and her parents rejected it for its invasiveness and potential complications. They were more willing to accept a less-than-ideal result. Therefore, nonsurgical orthodontic treatment was considered. The timing to start the comprehensive orthodontic treatment with dental camouflage could be during the adolescent or the postadolescent phase. In the planning of nonsurgical orthodontic camouflage, a nonextraction strategy was preferred because extractions in the maxillary arch would increase the severity of the anterior crossbite, whereas extractions in the mandibular arch would cause further lingual inclination of the mandibular incisors. TREATMENT PROGRESS
The phase 1 treatment was started with a bonded maxillary expander and facemask protraction (Fig 3). The patient was asked to activate the screw twice daily (0.25 mm per turn). After 2 weeks, the screw was successfully opened by 7 mm, and the posterior crossbite was corrected. Then it was fixed to hold the expanded space in the maxilla. Facemask protraction was used about 12 to 14 hours per day with a force of 500 cN per side. The protractor was worn for 1 year 2 months until the positive overjet was stable (Fig 4). The cephalometric analysis (Fig 5, Table) showed that the SNB angle decreased from 78.5 to 76.0 , whereas the mandibular plane angle increased from 26.3 to 29.3 . Therefore, the
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Fig 1. Pretreatment facial and intraoral photographs.
Fig 2. Pretreatment cephalometric and panoramic radiographs.
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Table. Cephalometric analyses at various stages of the
2-phase treatment Phase 1 treatment
Phase 2 treatment
After 2-year Before After Before After follow-up
Measurement Hard tissues SNA ( ) 75 75.2 74.5 78.1 SNB ( ) 78.5 76.0 79.3 79.3 ANB ( ) 3.5 0.8 4.9 1.2 PO-NB (mm) 2.4 3.3 1.0 3.1 Wits appraisal (mm) 6.5 4.6 7.8 4.9 FMA ( ) 26.3 29.3 28.7 31.7 SN-occlusal plane ( ) 17.9 20.7 15.6 16.5 Mx 1-NA (mm) 0.9 4.3 5.3 7.2 Mx 1-SN ( ) 90.2 94.2 107.7 109.4 Md 1-NB (mm) 0.1 0.4 1.7 3.2 Md 1-MP ( ) 66.8 71.6 61.2 83.0 Interincisor angle ( ) 166.1 155.8 151.4 127.7 Soft tissues E-plane–upper lip (mm) 3.2 2.0 6.4 4.9 E-plane–lower lip (mm) 1.4 2.0 5.5 3.6
77.7 78.5 0.8 4.0 5.1 30.9 18.4 6.1 106.6 2.5 78.5 135.6 5.1 4.3
mechanism of phase 1 treatment was the clockwise rotation of the mandible. The SNA angle did not increase significantly. Three years later when the patient was 12 years old, her crossbite relapsed with significant mandibular growth. Her concave facial profile deteriorated over time. Her mandibular incisors became severely lingually inclined. The maxillary left second premolar was impacted because of the missing deciduous second molar and the mesial movement of the first molar. Furthermore, there was not enough space for eruption of the maxillary right canine (Figs 6 and 7). The cervical vertebral image in the cephalogram indicated that the patient was undergoing her adolescent pubertal growth spurt (cervical vertebral stages 3 to 4) (Fig 8). The patient wanted to improve her appearance but refused the surgery. A comprehensive orthodontic treatment was initiated without extraction with preadjusted 0.022-in edgewise appliances of MBT prescriptions (3M Unitek, Monrovia, Calif).12 It started from the maxillary arch. To prevent the maxillary incisors from further proclination, an auxiliary rectangular wire was used to control the torque; meanwhile, a 0.016-in stainless steel round wire was used as the main archwire during the distalization of the maxillary first molars with an opening spring (Fig 9). The reaction to this distalization contributed to the correction of the anterior crossbite. The mandibular teeth were bracketed when the maxillary arch was well aligned. The brackets of the mandibular incisors were attached upside down so that a lingual root-torque prescription (16 ) was set in their slots. Short Class III elastics (1/4 in, 2 oz) were used with
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light forces to resolve the anterior crossbite. Later, through the interaction between the rectangular wires and the lingual root-torque slots, the mandibular incisors were gradually uprighted with the dentoalveolar modification over time (Fig 10). After debonding, maxillary vacuum-formed and mandibular fixed retainers from canine to canine were used. The patient was asked to wear the maxillary retainer full-time for 1 year and only at night for another year. The phase 1 treatment took 14 months, and the phase 2 treatment lasted 4 years 8 months. TREATMENT RESULTS
After the 2-phase orthodontic treatment, a balanced occlusion was established with good tooth alignment, adequate overjet and overbite, proper anterior guidance, and good intercuspation of the posterior teeth (Figs 11 and 12). No dehiscence or fenestration was found in the labial and lingual sides of the mandibular anterior range. The posttreatment extraoral photographs show the improved facial profile with a retracted lower lip and an increase of the inferior labial sulcus. The patient had significantly improved smile esthetics with more confidence (Fig 11). The chin still seemed mildly protruded, but the patient and her parents were satisfied with her teeth and facial appearance. The posttreatment panoramic radiograph showed good root parallelism. No significant root resorption, especially in the mandibular anterior region, was detected (Fig 13). The cephalometric analysis indicated that the skeletal discrepancy in the sagittal dimension was improved compared with before the phase 2 treatment (ANB angle, from 4.9 to 1.2 ). The increased SNA angle (from 74.5 to 78.1 ) showed that A-point was brought forward. The SNB angle remained stable at 79.3 . However, the FMA increased from 28.7 to 31.7 , indicating clockwise rotation of the mandible. Meanwhile, rotation of the occlusal plane (from 15.6 to 16.5 ) was observed. The inclination of the maxillary incisors increased from 107.7 to 109.4 ; this contributed to the correction of the anterior crossbite. The most dramatic change in this growing Class III patient was the improvement of the inclination of the mandibular incisors. They were decompensated from 61.2 to 83.0 . Therefore, the interincisor angle was improved from 151.4 to 127.7 . In addition, no root penetration from the lingual side of the symphysis was found (Fig 11). The superimpositions (Fig 14) proved our findings of skeletal and dental changes in the cephalometric analysis.
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Fig 3. Bonded expander was used with facemask protraction.
Fig 4. Intraoral photographs after phase 1 treatment.
Fig 5. Cephalometric and panoramic radiographs after phase 1 treatment.
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Fig 6. Facial and intraoral photographs before phase 2 treatment.
Fig 7. Dental casts before phase 2 treatment.
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Fig 8. Cephalometric and panoramic radiographs before phase 2 treatment.
Fig 9. Intraoral progress photographs. The treatment started from the maxillary arch, and a 0.017 3 0.025-in stainless steel wire was used as an auxiliary wire in the distalization of the maxillary first molars.
At the 2-year follow-up, the patient's stable occlusion was maintained along with satisfactory dental and smile esthetics (Figs 15 and 16). Cephalometrically, the inclination of the mandibular incisors slightly relapsed (Md 1-MP, from 83.0 to 81.9 ), but this was still much better than before the phase 2 treatment (61.2 ) (Fig 17). The superimpositions of the posttreatment and the 2-year follow-up tracings indicated that the patient had a little vertical growth,
and her skeletal structure and dental inclination were stable (Fig 18). DISCUSSION
The patient clearly had a skeletal Class III discrepancy when she was 8 years old at her first visit. The lingual inclination of the mandibular deciduous incisors (66.8 ) reminded us of the severity of her skeletal malocclusion. Therefore, the challenges in her treatment included
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Fig 10. Intraoral progress photographs. During the comprehensive treatment, the mandibular incisors were gradually uprighted.
improving her skeletal relationship and eliminating the compensation of mandibular incisors' lingual inclination as much as possible. Her 2-phase treatment consisted of early orthopedic intervention and comprehensive orthodontic treatment. Many investigators have proclaimed the importance of early intervention in the treatment of Class III malocclusions.2,3,13-15 It is essential to reduce the severity of the malocclusion and establish a suitable environment for jaw growth.2,3 It can not only provide early improvement of the facial profile, which psychosocially benefits patients and their parents, but also reduce the necessity of orthognathic surgery in the future.15 Previous studies have found that Class III patients treated at a younger age can obtain a greater skeletal component.16,17 In addition, the skeletal transverse problem can be resolved by maxillary disjunction with a palatal expender. The timing of early intervention should be in the mixed dentition and before pubertal growth.10,13,14 Therefore, in this patient, early treatment began right after she first came to us; it successfully improved her occlusion and facial appearance. The early treatment provided a suitable environment for her jaw growth, but it could not change her skeletal heredity. Her mandibular excessive growth during adolescence caused the relapse of the Class III malocclusion and deterioration of her facial appearance. This was attributed to the hereditary factor in her craniofacial development. A previous study proved that mandibular
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growth, in general, can be redirected instead of restrained in most Class III patients.18 Orthodontic camouflage is a less-than-ideal therapy, but it is valid if patients refuse surgery. It is a dilemma to determine the appropriate timing to start treatment. If it is carried out after the completion of facial growth, more stability can be expected. However, in this period, dental compensation is hard to achieve because of the limited remodeling of the alveolar bone. Comparatively, during pubertal growth, the alveolar bone is easier to modify, and more orthodontic decompensation can be expected. However, the stability of camouflage may be unpredictable if the patient still has growth potential when the treatment is finished. In this study, the comprehensive orthodontic treatment was carried out when the patient was 12 years old because of her urgent desire for improvement of her appearance. At that time, the patient had a lot of growth potential, which facilitated the alveolar remodeling. After 4 years 8 months of camouflage treatment, the patient was around 17 years old. Therefore, more treatment stability could be expected. The most dramatic changes in this patient were the improvement of her incisor inclination and the remodeling of the anterior alveolae. The incisor movement was partly controlled by the bracket system and the treatment mechanics.19 During the treatment, we used light-force elastics and gradually achieved our goals. The auxiliary rectangular wire (0.017 3 0.025-in
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Fig 11. Facial and intraoral photographs after phase 2 treatment.
Fig 12. Dental casts after phase 2 treatment.
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Fig 13. Cephalometric and panoramic radiographs after phase 2 treatment.
Fig 14. The overall maxillary and mandibular superimpositions of the initial and final tracings of the phase 2 treatment.
nickel-titanium) in the maxillary arch was used with a round main wire (0.016-in stainless steel) and an opening spring to create space for the impacted left second premolar and to move the anterior segment forward.
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Thereafter, the whole maxillary arch (with a 0.019 3 0.025-in nickel-titanium wire) was used as anchorage for retraction of the mandibular teeth to limit the deleterious effects of Class III elastics.
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Fig 15. Facial and intraoral photographs after 2 years of retention.
Fig 16. Dental casts after 2 years of retention.
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Fig 17. Cephalometric and panoramic radiographs after 2 years of retention.
Fig 18. The overall maxillary and mandibular superimpositions of the posttreatment and the 2-year follow-up tracings.
From the pretreatment vs posttreatment superimposition (Fig 14), A-point (deepest point between ANS and the maxillary incisal alveolus) and B-point (deepest
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point between pogonion and the mandibular incisal alveolus) followed the movement of the incisor roots. In the maxillary arch, the reaction of the distalization
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Fig 19. The dramatic changes of the mandibular anterior contour and B-point: A, before comprehensive treatment; B, after orthodontic treatment; C, at the 2-year follow-up.
of the first molars and the following Class III elastics pushed the anterior teeth forward. The maxillary incisors were moved bodily forward with good torque control. Since “bone traced the tooth movement,”9 the SNA angle increased from 74.5 to 78.1 with the sagittal improvement of A-point. This remarkable change was caused by both the maxillary sagittal growth and the bodily forward movement of the maxillary incisors. Similarly, Goldin19 claimed that a greater rate of Apoint advancement could be produced by labial root torque in orthodontic treatment compared with normal growth. He attributed the change to the greater dentoalveolar effect than the effect on the midsagittal basal bone. The decompensation of the inclination of the mandibular incisors should be carried out gently and gradually to prevent bone loss and gingival recession. The prescription for the mandibular incisors changed to 6 when we placed the brackets upside down intentionally. The wire in the mandibular arch was gradually changed from 0.016 3 0.022-in nickel-titanium to 0.019 3 0.025-in nickel-titanium. Meanwhile, short Class III elastics with a light force (1.5 oz) were worn. Through the interaction between the bracket slots and the archwires, the lingual root torque of the mandibular incisors was gradually expressed. The force of the Class III elastics prevented the incisors from proclination and retracted the mandibular dentition. In the end, the mandibular incisors were successfully uprighted and distalized (Figs 14 and 19). B-point was stabilized, and the SNB angle remained stable (79.3 ), despite the continuous growth of the chin (PO-NB, from 1.0 to 3.1mm) during the phase 2 treatment (Table). Furthermore, the reshaping of mandibular anterior region led to an esthetic contour of the mentolabial fold and the improvement of the patient's lower facial profile.20
Janson et al1 used “biofunctional brackets” with reverse torque prescriptions on the maxillary and mandibular incisors to control the proclination of the maxillary incisors and the retroclination of the mandibular incisors and to obtain bodily movement of the incisors. They used prescriptions of lingual crown torque on the maxillary anterior teeth (0 ) and labial crown torque on the mandibular anterior teeth (14 ) to counteract the Class III elastics because they believed that bodily movement would induce a greater alveolar remodeling response.1,19,21 Unlimited movement of the mandibular incisors is not possible because of the restriction imposed by the symphyseal bone.22 Because the bone support in the anterior region of a dental arch is limited in skeletal Class III patients, severe iatrogenic sequelae of orthodontic treatment should be considered, consisting of resorption of the labial cortical plate with subsequent gingival recession, dehiscence, or fenestration and lengthening of the clinical crowns of the mandibular incisors or resorption of their lingual cortical plates.6,22,23 After observing the changes in alveolar bone thickness from retraction of the anterior teeth, Sarikaya et al22 inferred that light forces and long-term activations to allow the alveolar bone to adapt might be helpful in reducing the risk of adverse effects. Their proposals were exactly what we did for this patient. The force of Class III elastics we used was about 2 oz (56.7 g), and the comprehensive treatment took 4 years 8 months. No negative effects have been seen in this patient. Another reason for the light force we used in Class III elastics was to prevent extrusion of the maxillary posterior teeth; this would have caused a severe backward rotation of the mandible. Although this treatment-induced rotation assists the resolution of the anterior crossbite, the consequent increase of facial height will cause the facial esthetics to deteriorate and might cause lip incompetence.24 The
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patient's mandibular angle (FMA) increased by 3 (from 28.7 to 31.7 ) during the comprehensive treatment and relapsed a little during the retention (back to 30.9 ). The 2-year follow-up records (Figs 15-17, Table) and the superimpostions (Fig 18) indicated that the treatment results were quite stable. The patient was 19 years old with little potential mandibular growth when she visited us the last time. Therefore, our 2-phase treatment was proved successful. We suggested that the patient should have genioplasty, because it would remarkably improve her facial appearance. But she refused it again. However, this protocol of “orthodontic decompensation” with dentoalveolar remodeling in a growing Class III patient and then genioplasty in adulthood could be considered in the future. CONCLUSIONS
A skeletal Class III girl was successfully treated in 2 phases without surgery. In the comprehensive orthodontic treatment, “orthodontic decompensation” and Class III correction were achieved by gradual dentoalveolar remodeling during the patient's growth. Proper treatment mechanics and sufficient treatment time were the keys to success. REFERENCES 1. Janson G, de Souza JE, Alves Fde A, Andrade P Jr, Nakamura A, de Freitas MR, et al. Extreme dentoalveolar compensation in the treatment of Class III malocclusion. Am J Orthod Dentofacial Orthop 2005;128:787-94. 2. Sugawara J, Aymach Z, Hin H, Nanda R. One-phase vs 2-phase treatment for developing Class III malocclusion: a comparison of identical twins. Am J Orthod Dentofacial Orthop 2012;141:e11-22. 3. Jiang J, Lin J, Ji C. Two-stage treatment of skeletal Class III malocclusion during the early permanent dentition. Am J Orthod Dentofacial Orthop 2005;128:520-7. 4. Lin J, Gu Y. Preliminary investigation of nonsurgical treatment of severe skeletal Class III malocclusion in the permanent dentition. Angle Orthod 2003;73:401-10. 5. Sperry TP, Speidel TM, Isaacson RJ, Worms FW. The role of dental compensations in the orthodontic treatment of mandibular prognathism. Angle Orthod 1977;47:293-9. 6. Handelman CS. The anterior alveolus: its importance in limiting orthodontic treatment and its influence on the occurrence of iatrogenic sequelae. Angle Orthod 1996;66:95-109.
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7. Yanagita T, Kuroda S, Takano-Yamamoto T, Yamashiro T. Class III malocclusion with complex problems of lateral open bite and severe crowding successfully treated with miniscrew anchorage and lingual orthodontic brackets. Am J Orthod Dentofacial Orthop 2011;139:679-89. 8. Reitan K. Effects of force magnitude and direction of tooth movement on different alveolar bone types. Angle Orthod 1964;34:244-55. 9. Vardimon AD, Oren E, Ben-Bassat Y. Cortical bone remodeling/ tooth movement ratio during maxillary incisor retraction with tip versus torque movements. Am J Orthod Dentofacial Orthop 1998;114:520-9. 10. Baccetti T, Franchi L, McNamara JA Jr. The cervical vertebral maturation (CVM) method for the assessment of optimal treatment timing in dentofacial orthopedics. Semin Orthod 2005;11: 119-29. 11. Troy BA, Shanker S, Fields HW, Vig K, Johnston W. Comparison of incisor inclination in patients with Class III malocclusion treated with orthognathic surgery or orthodontic camouflage. Am J Orthod Dentofacial Orthop 2009;135:146.e1-9; discussion, 146-7. 12. McLaughlin RP, Bennett JC, Trevisi HJ. Systemized orthodontic treatment mechanics. Edinburgh, United Kingdom: Mosby; 2001. 13. Graber LW, Vanarsdall RL Jr, Vig KW. Orthodontics: current principles and techniques. 5th ed. Philadelphia: Elsevier; 2011. 14. Proffit WR, Fields HW Jr, Sarver DM. Contemporary orthodontics. 5th ed. Philadelphia: Elsevier; 2006. 15. Kanno Z, Kim Y, Soma K. Early correction of a developing skeletal Class III malocclusion. Angle Orthod 2007;77:549-56. 16. Sakamoto T. Effective timing for the application of orthopedic force in the skeletal Class III malocclusion. Am J Orthod 1981; 80:411-6. 17. Mermigos J, Full CA, Andreasen G. Protraction of the maxillofacial complex. Am J Orthod Dentofacial Orthop 1990;98:47-55. 18. Sugawara J, Mitani H. Facial growth of skeletal Class III malocclusion and the effects, limitations, and long-term dentofacial adaptations to chincap therapy. Semin Orthod 1997;3:244-54. 19. Goldin B. Labial root torque: effect on the maxilla and incisor root apex. Am J Orthod Dentofacial Orthop 1989;95:208-19. 20. Belinfante LS. Esthetic contouring of the mentolabial fold as an adjunct to the osseous sliding genioplasty. J Oral Maxillofac Surg 1997;55:1023-5. 21. Wainwright WM. Faciolingual tooth movement: its influence on the root and cortical plate. Am J Orthod 1973;64:278-302. 22. Sarikaya S, Haydar B, Ciger S, Ariyurek M. Changes in alveolar bone thickness due to retraction of anterior teeth. Am J Orthod Dentofacial Orthop 2002;122:15-26. 23. Wehrbein H, Bauer W, Diedrich P. Mandibular incisors, alveolar bone, and symphysis after orthodontic treatment. A retrospective study. Am J Orthod Dentofacial Orthop 1996;110:239-46. 24. Bilodeau JE. Vertical considerations in diagnosis and treatment. A surgical orthodontic case report. Am J Orthod Dentofacial Orthop 1995;107:91-100.
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Orthodontic decompensation and correction of skeletal Class III malocclusion with gradual dentoalveolar remodeling in a growing patient Bin Cai,a Xiao-Guang Zhao,b and Lu-Sai Xiangc Guangzhou, Guangdong, China
An 8-year-old girl with a skeletal Class III malocclusion was treated in 2 phases. Maxillary expansion and protraction were carried out as the early intervention. However, her maxillary hypoplasia and mandibular hyperplasia deteriorated with age. The phase 2 comprehensive treatment began with proper mechanics when she was 12 years old with growth potential. In the maxillary arch, an auxiliary rectangular wire was used with a round main wire and an opening spring to create space for the impacted teeth and to bodily move the anterior teeth forward. Decompensation of mandibular incisors and correction of the Class III malocclusion were achieved by short Class III elastics with light forces and a gentle interaction between the rectangular wires and the lingual roottorque slots. The phase 2 active treatment period was 4 years 8 months. The 2-year follow-up indicated that our treatment results were quite stable. (Am J Orthod Dentofacial Orthop 2014;145:367-80)
I
n the treatment of skeletal Class III malocclusion, there is no clear borderline between what can be achieved by orthodontic camouflage and what inevitably requires orthognathic surgery. Comparatively, orthognathic surgery could obtain substantial skeletal improvement as well as favorable tooth inclinations by the presurgical decompensation. However, camouflage treatment demands more time and high patient compliance, although the treatment expenses and risks are lower.1 For patients who do not want the risk of surgery, early orthodontic intervention in the mixed dentition followed by comprehensive treatment in the early permanent dentition is a valid therapy.2,3 Traditional orthodontic camouflage of skeletal Class III malocclusion always results in more lingual inclination of the mandibular incisors and more proclination of the maxillary incisors for compensation of a skeletal discrepancy.4 However, excessive inclination of the incisors will not only ruin the dental esthetics but also From the Department of Orthodontics, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China. a Associate professor. b Lecturer. c Postgraduate student. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Xiao-Guang Zhao, Department of Orthodontics, Hospital of Stomatology, Sun Yat-sen University, 56 Lingyuan West Rd, Guangzhou, Guangdong, China 510055; e-mail, [email protected]. Submitted, revised and accepted, April 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.04.026
harm the surrounding periodontal tissues, probably from the traumatic occlusal forces.5,6 Authors of a previous study attempted to improve the compensative inclination of the mandibular incisors with mandibular skeletal anchorage.7 The patient's pubertal growth is the optimal timing for routine orthodontic treatment because modifications of dentoalveolar bone are easier in this stage. In general, bone around the alveolar socket will remodel to the some extent after orthodontic tooth movement.8,9 If orthodontists could take the advantage of this period to achieve “orthodontic decompensation” and to correct a Class III malocclusion at the same time by gradual alveolar remodeling with comprehensive orthodontic treatment, further inclination of the incisors and unfavorable side effects could be avoided. How much could the dentoalveolar remodeling compensate for the base bone discrepancy? To answer this question, we present a skeletal Class III patient treated with early intervention and orthodontic camouflage. In her comprehensive orthodontic treatment, we attempted to decompensate the incisor inclination during her growing stage with dentoaveolar remodeling. DIAGNOSIS AND ETIOLOGY
An 8-year-old girl came for orthodontic consultation with chief complaints of an anterior crossbite and a dished-in face. Her parents said that her psychology was negatively affected by her unesthetic facial 367
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appearance. Her medical history showed no systemic diseases or developmental anomalies. Her parents did not have Class III characteristics. The patient had a retrognathic maxilla and a prognathic mandible with a sharp nasolabial angle and a concave facial profile (Fig 1). As shown by the cephalometric analysis, the ANB angle was 3.5 , and the Wits appraisal was 6.5 mm (Fig 2, Table). The intraoral examination indicated a Class III malocclusion with an anterior crossbite and a unilateral crossbite. Cephalometrically, she had lingually inclined mandibular deciduous incisors (Md 1 to MP, 66.8 ) and an excessive interincisal angle (166.1 ), which was the dental compensation of the skeletal Class III discrepancy. Her cephalogram showed that the lower border of the second through the fourth cervical vertebrae had no concavity, indicating that she was at cervical vertebral stage 1.10 Considering the severity of her skeletal problem, we explained the possibility of orthognathic surgery to the patient and her parents. However, they were reluctant to undertake the risks of surgery. TREATMENT OBJECTIVES
The proposed treatment included 2 phases: early orthopedic intervention and comprehensive treatment. Skeletally, we proposed to promote sagittal growth of the maxilla before her pubertal growth spurt to improve the midfacial deficiency and to eliminate the acute nasolabial angle; this could be done in the first stage. Meanwhile, the transverse coordination of the maxilla and the mandible could be carried out by maxillary disjunction with a palatal expander. Since it is impossible to limit the absolute growth of mandible, changing the growth direction could be helpful in the improvement of her skeletal discrepancy. However, we did not expect to increase her facial height much because it would ruin her facial balance. If her mandibular growth exceeded the maxillary growth too much, orthognathic surgery could not be avoided. We explained this to the patient and her parents before the treatment started. Because the patient was reluctant to have surgery, dental camouflage became the solution to compensate for the skeletal discrepancy. The goals consisted of achieving good dental alignment and establishing posterior interdigitation with Class I molar and canine relationships. In addition, to obtain better facial esthetics and more stability, we attempted to decompensate the inclination of the maxillary and mandibular incisors by dentoaveolar remodeling in her phase 2 treatment.
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TREATMENT ALTERNATIVES
Since the patient and her parents cared about her facial appearance, an early intervention of the skeletal discrepancy would benefit her psychological health and make the following treatment easier as well.2,3 Therefore, a plan of 2-phase treatment was made for her. In phase 1 of the treatment, facemask protraction and chincap were 2 alternatives to improve the patient's facial appearance. Because she had a posterior crossbite, maxillary retrognathism, and mandibular prognathism, the maxillary expander with facemask protraction was adopted. In the pretreatment cephalogram, her cervical vertebral maturation was judged to be at least 2 years before the pubertal growth spurt (stage 1); this was good timing for facemask protraction.10 There are different types of expanders including hyrax, Haas, and bonded expanders. Because the maxillary first molars had not erupted yet, a bonded expander was the choice for better retention. Phase 2 treatment would depend on mandibular growth and the patient's preference. Orthognathic surgery is a viable, and even optimal, option especially for a severe skeletal discrepancy.11 It could correct not only the dental problems but also the skeletal and soft tissue discrepancies. However, the patient and her parents rejected it for its invasiveness and potential complications. They were more willing to accept a less-than-ideal result. Therefore, nonsurgical orthodontic treatment was considered. The timing to start the comprehensive orthodontic treatment with dental camouflage could be during the adolescent or the postadolescent phase. In the planning of nonsurgical orthodontic camouflage, a nonextraction strategy was preferred because extractions in the maxillary arch would increase the severity of the anterior crossbite, whereas extractions in the mandibular arch would cause further lingual inclination of the mandibular incisors. TREATMENT PROGRESS
The phase 1 treatment was started with a bonded maxillary expander and facemask protraction (Fig 3). The patient was asked to activate the screw twice daily (0.25 mm per turn). After 2 weeks, the screw was successfully opened by 7 mm, and the posterior crossbite was corrected. Then it was fixed to hold the expanded space in the maxilla. Facemask protraction was used about 12 to 14 hours per day with a force of 500 cN per side. The protractor was worn for 1 year 2 months until the positive overjet was stable (Fig 4). The cephalometric analysis (Fig 5, Table) showed that the SNB angle decreased from 78.5 to 76.0 , whereas the mandibular plane angle increased from 26.3 to 29.3 . Therefore, the
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Fig 1. Pretreatment facial and intraoral photographs.
Fig 2. Pretreatment cephalometric and panoramic radiographs.
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Table. Cephalometric analyses at various stages of the
2-phase treatment Phase 1 treatment
Phase 2 treatment
After 2-year Before After Before After follow-up
Measurement Hard tissues SNA ( ) 75 75.2 74.5 78.1 SNB ( ) 78.5 76.0 79.3 79.3 ANB ( ) 3.5 0.8 4.9 1.2 PO-NB (mm) 2.4 3.3 1.0 3.1 Wits appraisal (mm) 6.5 4.6 7.8 4.9 FMA ( ) 26.3 29.3 28.7 31.7 SN-occlusal plane ( ) 17.9 20.7 15.6 16.5 Mx 1-NA (mm) 0.9 4.3 5.3 7.2 Mx 1-SN ( ) 90.2 94.2 107.7 109.4 Md 1-NB (mm) 0.1 0.4 1.7 3.2 Md 1-MP ( ) 66.8 71.6 61.2 83.0 Interincisor angle ( ) 166.1 155.8 151.4 127.7 Soft tissues E-plane–upper lip (mm) 3.2 2.0 6.4 4.9 E-plane–lower lip (mm) 1.4 2.0 5.5 3.6
77.7 78.5 0.8 4.0 5.1 30.9 18.4 6.1 106.6 2.5 78.5 135.6 5.1 4.3
mechanism of phase 1 treatment was the clockwise rotation of the mandible. The SNA angle did not increase significantly. Three years later when the patient was 12 years old, her crossbite relapsed with significant mandibular growth. Her concave facial profile deteriorated over time. Her mandibular incisors became severely lingually inclined. The maxillary left second premolar was impacted because of the missing deciduous second molar and the mesial movement of the first molar. Furthermore, there was not enough space for eruption of the maxillary right canine (Figs 6 and 7). The cervical vertebral image in the cephalogram indicated that the patient was undergoing her adolescent pubertal growth spurt (cervical vertebral stages 3 to 4) (Fig 8). The patient wanted to improve her appearance but refused the surgery. A comprehensive orthodontic treatment was initiated without extraction with preadjusted 0.022-in edgewise appliances of MBT prescriptions (3M Unitek, Monrovia, Calif).12 It started from the maxillary arch. To prevent the maxillary incisors from further proclination, an auxiliary rectangular wire was used to control the torque; meanwhile, a 0.016-in stainless steel round wire was used as the main archwire during the distalization of the maxillary first molars with an opening spring (Fig 9). The reaction to this distalization contributed to the correction of the anterior crossbite. The mandibular teeth were bracketed when the maxillary arch was well aligned. The brackets of the mandibular incisors were attached upside down so that a lingual root-torque prescription (16 ) was set in their slots. Short Class III elastics (1/4 in, 2 oz) were used with
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light forces to resolve the anterior crossbite. Later, through the interaction between the rectangular wires and the lingual root-torque slots, the mandibular incisors were gradually uprighted with the dentoalveolar modification over time (Fig 10). After debonding, maxillary vacuum-formed and mandibular fixed retainers from canine to canine were used. The patient was asked to wear the maxillary retainer full-time for 1 year and only at night for another year. The phase 1 treatment took 14 months, and the phase 2 treatment lasted 4 years 8 months. TREATMENT RESULTS
After the 2-phase orthodontic treatment, a balanced occlusion was established with good tooth alignment, adequate overjet and overbite, proper anterior guidance, and good intercuspation of the posterior teeth (Figs 11 and 12). No dehiscence or fenestration was found in the labial and lingual sides of the mandibular anterior range. The posttreatment extraoral photographs show the improved facial profile with a retracted lower lip and an increase of the inferior labial sulcus. The patient had significantly improved smile esthetics with more confidence (Fig 11). The chin still seemed mildly protruded, but the patient and her parents were satisfied with her teeth and facial appearance. The posttreatment panoramic radiograph showed good root parallelism. No significant root resorption, especially in the mandibular anterior region, was detected (Fig 13). The cephalometric analysis indicated that the skeletal discrepancy in the sagittal dimension was improved compared with before the phase 2 treatment (ANB angle, from 4.9 to 1.2 ). The increased SNA angle (from 74.5 to 78.1 ) showed that A-point was brought forward. The SNB angle remained stable at 79.3 . However, the FMA increased from 28.7 to 31.7 , indicating clockwise rotation of the mandible. Meanwhile, rotation of the occlusal plane (from 15.6 to 16.5 ) was observed. The inclination of the maxillary incisors increased from 107.7 to 109.4 ; this contributed to the correction of the anterior crossbite. The most dramatic change in this growing Class III patient was the improvement of the inclination of the mandibular incisors. They were decompensated from 61.2 to 83.0 . Therefore, the interincisor angle was improved from 151.4 to 127.7 . In addition, no root penetration from the lingual side of the symphysis was found (Fig 11). The superimpositions (Fig 14) proved our findings of skeletal and dental changes in the cephalometric analysis.
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Fig 3. Bonded expander was used with facemask protraction.
Fig 4. Intraoral photographs after phase 1 treatment.
Fig 5. Cephalometric and panoramic radiographs after phase 1 treatment.
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Fig 6. Facial and intraoral photographs before phase 2 treatment.
Fig 7. Dental casts before phase 2 treatment.
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Fig 8. Cephalometric and panoramic radiographs before phase 2 treatment.
Fig 9. Intraoral progress photographs. The treatment started from the maxillary arch, and a 0.017 3 0.025-in stainless steel wire was used as an auxiliary wire in the distalization of the maxillary first molars.
At the 2-year follow-up, the patient's stable occlusion was maintained along with satisfactory dental and smile esthetics (Figs 15 and 16). Cephalometrically, the inclination of the mandibular incisors slightly relapsed (Md 1-MP, from 83.0 to 81.9 ), but this was still much better than before the phase 2 treatment (61.2 ) (Fig 17). The superimpositions of the posttreatment and the 2-year follow-up tracings indicated that the patient had a little vertical growth,
and her skeletal structure and dental inclination were stable (Fig 18). DISCUSSION
The patient clearly had a skeletal Class III discrepancy when she was 8 years old at her first visit. The lingual inclination of the mandibular deciduous incisors (66.8 ) reminded us of the severity of her skeletal malocclusion. Therefore, the challenges in her treatment included
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Fig 10. Intraoral progress photographs. During the comprehensive treatment, the mandibular incisors were gradually uprighted.
improving her skeletal relationship and eliminating the compensation of mandibular incisors' lingual inclination as much as possible. Her 2-phase treatment consisted of early orthopedic intervention and comprehensive orthodontic treatment. Many investigators have proclaimed the importance of early intervention in the treatment of Class III malocclusions.2,3,13-15 It is essential to reduce the severity of the malocclusion and establish a suitable environment for jaw growth.2,3 It can not only provide early improvement of the facial profile, which psychosocially benefits patients and their parents, but also reduce the necessity of orthognathic surgery in the future.15 Previous studies have found that Class III patients treated at a younger age can obtain a greater skeletal component.16,17 In addition, the skeletal transverse problem can be resolved by maxillary disjunction with a palatal expender. The timing of early intervention should be in the mixed dentition and before pubertal growth.10,13,14 Therefore, in this patient, early treatment began right after she first came to us; it successfully improved her occlusion and facial appearance. The early treatment provided a suitable environment for her jaw growth, but it could not change her skeletal heredity. Her mandibular excessive growth during adolescence caused the relapse of the Class III malocclusion and deterioration of her facial appearance. This was attributed to the hereditary factor in her craniofacial development. A previous study proved that mandibular
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growth, in general, can be redirected instead of restrained in most Class III patients.18 Orthodontic camouflage is a less-than-ideal therapy, but it is valid if patients refuse surgery. It is a dilemma to determine the appropriate timing to start treatment. If it is carried out after the completion of facial growth, more stability can be expected. However, in this period, dental compensation is hard to achieve because of the limited remodeling of the alveolar bone. Comparatively, during pubertal growth, the alveolar bone is easier to modify, and more orthodontic decompensation can be expected. However, the stability of camouflage may be unpredictable if the patient still has growth potential when the treatment is finished. In this study, the comprehensive orthodontic treatment was carried out when the patient was 12 years old because of her urgent desire for improvement of her appearance. At that time, the patient had a lot of growth potential, which facilitated the alveolar remodeling. After 4 years 8 months of camouflage treatment, the patient was around 17 years old. Therefore, more treatment stability could be expected. The most dramatic changes in this patient were the improvement of her incisor inclination and the remodeling of the anterior alveolae. The incisor movement was partly controlled by the bracket system and the treatment mechanics.19 During the treatment, we used light-force elastics and gradually achieved our goals. The auxiliary rectangular wire (0.017 3 0.025-in
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Fig 11. Facial and intraoral photographs after phase 2 treatment.
Fig 12. Dental casts after phase 2 treatment.
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Fig 13. Cephalometric and panoramic radiographs after phase 2 treatment.
Fig 14. The overall maxillary and mandibular superimpositions of the initial and final tracings of the phase 2 treatment.
nickel-titanium) in the maxillary arch was used with a round main wire (0.016-in stainless steel) and an opening spring to create space for the impacted left second premolar and to move the anterior segment forward.
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Thereafter, the whole maxillary arch (with a 0.019 3 0.025-in nickel-titanium wire) was used as anchorage for retraction of the mandibular teeth to limit the deleterious effects of Class III elastics.
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Fig 15. Facial and intraoral photographs after 2 years of retention.
Fig 16. Dental casts after 2 years of retention.
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Fig 17. Cephalometric and panoramic radiographs after 2 years of retention.
Fig 18. The overall maxillary and mandibular superimpositions of the posttreatment and the 2-year follow-up tracings.
From the pretreatment vs posttreatment superimposition (Fig 14), A-point (deepest point between ANS and the maxillary incisal alveolus) and B-point (deepest
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point between pogonion and the mandibular incisal alveolus) followed the movement of the incisor roots. In the maxillary arch, the reaction of the distalization
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Fig 19. The dramatic changes of the mandibular anterior contour and B-point: A, before comprehensive treatment; B, after orthodontic treatment; C, at the 2-year follow-up.
of the first molars and the following Class III elastics pushed the anterior teeth forward. The maxillary incisors were moved bodily forward with good torque control. Since “bone traced the tooth movement,”9 the SNA angle increased from 74.5 to 78.1 with the sagittal improvement of A-point. This remarkable change was caused by both the maxillary sagittal growth and the bodily forward movement of the maxillary incisors. Similarly, Goldin19 claimed that a greater rate of Apoint advancement could be produced by labial root torque in orthodontic treatment compared with normal growth. He attributed the change to the greater dentoalveolar effect than the effect on the midsagittal basal bone. The decompensation of the inclination of the mandibular incisors should be carried out gently and gradually to prevent bone loss and gingival recession. The prescription for the mandibular incisors changed to 6 when we placed the brackets upside down intentionally. The wire in the mandibular arch was gradually changed from 0.016 3 0.022-in nickel-titanium to 0.019 3 0.025-in nickel-titanium. Meanwhile, short Class III elastics with a light force (1.5 oz) were worn. Through the interaction between the bracket slots and the archwires, the lingual root torque of the mandibular incisors was gradually expressed. The force of the Class III elastics prevented the incisors from proclination and retracted the mandibular dentition. In the end, the mandibular incisors were successfully uprighted and distalized (Figs 14 and 19). B-point was stabilized, and the SNB angle remained stable (79.3 ), despite the continuous growth of the chin (PO-NB, from 1.0 to 3.1mm) during the phase 2 treatment (Table). Furthermore, the reshaping of mandibular anterior region led to an esthetic contour of the mentolabial fold and the improvement of the patient's lower facial profile.20
Janson et al1 used “biofunctional brackets” with reverse torque prescriptions on the maxillary and mandibular incisors to control the proclination of the maxillary incisors and the retroclination of the mandibular incisors and to obtain bodily movement of the incisors. They used prescriptions of lingual crown torque on the maxillary anterior teeth (0 ) and labial crown torque on the mandibular anterior teeth (14 ) to counteract the Class III elastics because they believed that bodily movement would induce a greater alveolar remodeling response.1,19,21 Unlimited movement of the mandibular incisors is not possible because of the restriction imposed by the symphyseal bone.22 Because the bone support in the anterior region of a dental arch is limited in skeletal Class III patients, severe iatrogenic sequelae of orthodontic treatment should be considered, consisting of resorption of the labial cortical plate with subsequent gingival recession, dehiscence, or fenestration and lengthening of the clinical crowns of the mandibular incisors or resorption of their lingual cortical plates.6,22,23 After observing the changes in alveolar bone thickness from retraction of the anterior teeth, Sarikaya et al22 inferred that light forces and long-term activations to allow the alveolar bone to adapt might be helpful in reducing the risk of adverse effects. Their proposals were exactly what we did for this patient. The force of Class III elastics we used was about 2 oz (56.7 g), and the comprehensive treatment took 4 years 8 months. No negative effects have been seen in this patient. Another reason for the light force we used in Class III elastics was to prevent extrusion of the maxillary posterior teeth; this would have caused a severe backward rotation of the mandible. Although this treatment-induced rotation assists the resolution of the anterior crossbite, the consequent increase of facial height will cause the facial esthetics to deteriorate and might cause lip incompetence.24 The
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patient's mandibular angle (FMA) increased by 3 (from 28.7 to 31.7 ) during the comprehensive treatment and relapsed a little during the retention (back to 30.9 ). The 2-year follow-up records (Figs 15-17, Table) and the superimpostions (Fig 18) indicated that the treatment results were quite stable. The patient was 19 years old with little potential mandibular growth when she visited us the last time. Therefore, our 2-phase treatment was proved successful. We suggested that the patient should have genioplasty, because it would remarkably improve her facial appearance. But she refused it again. However, this protocol of “orthodontic decompensation” with dentoalveolar remodeling in a growing Class III patient and then genioplasty in adulthood could be considered in the future. CONCLUSIONS
A skeletal Class III girl was successfully treated in 2 phases without surgery. In the comprehensive orthodontic treatment, “orthodontic decompensation” and Class III correction were achieved by gradual dentoalveolar remodeling during the patient's growth. Proper treatment mechanics and sufficient treatment time were the keys to success. REFERENCES 1. Janson G, de Souza JE, Alves Fde A, Andrade P Jr, Nakamura A, de Freitas MR, et al. Extreme dentoalveolar compensation in the treatment of Class III malocclusion. Am J Orthod Dentofacial Orthop 2005;128:787-94. 2. Sugawara J, Aymach Z, Hin H, Nanda R. One-phase vs 2-phase treatment for developing Class III malocclusion: a comparison of identical twins. Am J Orthod Dentofacial Orthop 2012;141:e11-22. 3. Jiang J, Lin J, Ji C. Two-stage treatment of skeletal Class III malocclusion during the early permanent dentition. Am J Orthod Dentofacial Orthop 2005;128:520-7. 4. Lin J, Gu Y. Preliminary investigation of nonsurgical treatment of severe skeletal Class III malocclusion in the permanent dentition. Angle Orthod 2003;73:401-10. 5. Sperry TP, Speidel TM, Isaacson RJ, Worms FW. The role of dental compensations in the orthodontic treatment of mandibular prognathism. Angle Orthod 1977;47:293-9. 6. Handelman CS. The anterior alveolus: its importance in limiting orthodontic treatment and its influence on the occurrence of iatrogenic sequelae. Angle Orthod 1996;66:95-109.
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7. Yanagita T, Kuroda S, Takano-Yamamoto T, Yamashiro T. Class III malocclusion with complex problems of lateral open bite and severe crowding successfully treated with miniscrew anchorage and lingual orthodontic brackets. Am J Orthod Dentofacial Orthop 2011;139:679-89. 8. Reitan K. Effects of force magnitude and direction of tooth movement on different alveolar bone types. Angle Orthod 1964;34:244-55. 9. Vardimon AD, Oren E, Ben-Bassat Y. Cortical bone remodeling/ tooth movement ratio during maxillary incisor retraction with tip versus torque movements. Am J Orthod Dentofacial Orthop 1998;114:520-9. 10. Baccetti T, Franchi L, McNamara JA Jr. The cervical vertebral maturation (CVM) method for the assessment of optimal treatment timing in dentofacial orthopedics. Semin Orthod 2005;11: 119-29. 11. Troy BA, Shanker S, Fields HW, Vig K, Johnston W. Comparison of incisor inclination in patients with Class III malocclusion treated with orthognathic surgery or orthodontic camouflage. Am J Orthod Dentofacial Orthop 2009;135:146.e1-9; discussion, 146-7. 12. McLaughlin RP, Bennett JC, Trevisi HJ. Systemized orthodontic treatment mechanics. Edinburgh, United Kingdom: Mosby; 2001. 13. Graber LW, Vanarsdall RL Jr, Vig KW. Orthodontics: current principles and techniques. 5th ed. Philadelphia: Elsevier; 2011. 14. Proffit WR, Fields HW Jr, Sarver DM. Contemporary orthodontics. 5th ed. Philadelphia: Elsevier; 2006. 15. Kanno Z, Kim Y, Soma K. Early correction of a developing skeletal Class III malocclusion. Angle Orthod 2007;77:549-56. 16. Sakamoto T. Effective timing for the application of orthopedic force in the skeletal Class III malocclusion. Am J Orthod 1981; 80:411-6. 17. Mermigos J, Full CA, Andreasen G. Protraction of the maxillofacial complex. Am J Orthod Dentofacial Orthop 1990;98:47-55. 18. Sugawara J, Mitani H. Facial growth of skeletal Class III malocclusion and the effects, limitations, and long-term dentofacial adaptations to chincap therapy. Semin Orthod 1997;3:244-54. 19. Goldin B. Labial root torque: effect on the maxilla and incisor root apex. Am J Orthod Dentofacial Orthop 1989;95:208-19. 20. Belinfante LS. Esthetic contouring of the mentolabial fold as an adjunct to the osseous sliding genioplasty. J Oral Maxillofac Surg 1997;55:1023-5. 21. Wainwright WM. Faciolingual tooth movement: its influence on the root and cortical plate. Am J Orthod 1973;64:278-302. 22. Sarikaya S, Haydar B, Ciger S, Ariyurek M. Changes in alveolar bone thickness due to retraction of anterior teeth. Am J Orthod Dentofacial Orthop 2002;122:15-26. 23. Wehrbein H, Bauer W, Diedrich P. Mandibular incisors, alveolar bone, and symphysis after orthodontic treatment. A retrospective study. Am J Orthod Dentofacial Orthop 1996;110:239-46. 24. Bilodeau JE. Vertical considerations in diagnosis and treatment. A surgical orthodontic case report. Am J Orthod Dentofacial Orthop 1995;107:91-100.
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