CASE REPORT

Distalization of the mandibular dentition with mini-implants to correct a Class III with a midline deviation

Kyu-Rhim Chung,a Seong-Hun Kim,b HyeRan Choo,c Yoon-Ah Kook,d and Jason B. Copee Uijongbu and Seoul, Korea, Philadelphia, Pa, and Dallas, Tex

This article describes the orthodontic treatment for a young woman, aged 23 years 5 months, with a Class III malocclusion and a deviated midline. Two orthodontic mini-implants (C-implants, CIMPLANT Company, Seoul, Korea) were placed in the interdental spaces between the mandibular second premolars and first mo- lars. The treatment plan consisted of distalizing the mandibular dentition asymmetrically and creating space for en-masse retraction of the mandibular anterior teeth. C-implants were placed to provide for Class I intra-arch . The head design of the C-implant minimizes gingival irritation during orthodontic treatment. Sliding jigs were applied buccally for distalization of the mandibular posterior teeth. The active treatment period was 18 months. Normal and overjet were obtained, and facial balance was improved. (Am J Orthod Dentofacial Orthop 2010;137:135-46)

very orthodontic tooth movement is accompa- patients. Therefore, several authors have attempted to nied by a reaction. This can make it difficult to treat this type of malocclusion by distal tooth movement Ecorrect a malocclusion by using intraoral appli- alone. For example, animal studies and clinical investi- ances alone, especially when complete distal movement gations have used conventional implants as absolute of the mandibular dentition is planned in nonsurgical anchorage2-4 and miniplates for or distalization Class III malocclusion treatment. Traditionally, fixed ap- of the mandibular posterior teeth.5,6 Because all portions pliances and intermaxillary elastics have been used to of the anchor plates and screws were placed outside the move mandibular molars distally, often resulting in un- dentition in these studies, it was possible to move the desirable proclination of the maxillary incisors and ex- mandibular molars without disturbing tooth movement. trusion of the maxillary molars as reciprocal side Recently, the mechanics of group distal movement effects.1 This can cause an esthetic problem and instabil- of teeth with microscrew implant anchorage was intro- ity, especially in long-faced adults. Also, because inter- duced.7 A distalizing force is applied to the canines maxillary elastic wear requires patient compliance, it is through a nickel-titanium (NiTi) coil spring connecting difficult to predict the final result in uncooperative the miniscrew to hooks on the archwire. The primary treatment effect in the mandible is distal tipping move- a President, Korean Society of Speedy Orthodontics, Seoul, Korea. ment of the posterior teeth concurrent with uprighting b Assistant professor, Department of Orthodontics, Catholic University of and distal movement of the anterior teeth. Because there Korea, Uijongbu St. Mary’s Hospital, Uijongbu, Korea. is no force to move the maxillary anterior teeth forward c Attending orthodontist, The Children’s Hospital of Philadelphia; clinical asso- ciate, University of Pennsylvania School of Dental Medicine, Philadelphia, Pa. (via Class III elastics), there are no side effects on the d Professor and chairman, Department of Orthodontics, Catholic University of maxillary anterior teeth in microscrew implant-aided Korea, Seoul St. Mary’s Hospital, Seoul, Korea. mechanics. Therefore, distal movement assisted by e Adjunct clinical assistant professor, Department of Orthodontics; adjunct assistant professor, Department of Oral and Maxillofacial Surgery, Baylor a rigid orthodontic implant can be a good alternative College of Dentistry, Dallas, Tex. for treatment when intermaxillary elastics are not indi- Partly supported by the Korean Society of Speedy Orthodontics, the alumni fund cated or the patient is uncooperative. of the Department of Dentistry, and the Graduate School of Clinical Dental Sci- ence, Catholic University of Korea. The stability of temporary skeletal anchorage The authors report no commercial, proprietary, or financial interest in the prod- devices is achieved from primary mechanical retention ucts or companies described in this article. between the implant surface and the cortical bone, and Reprint requests to: Seong-Hun Kim, Catholic University of Korea, Uijongbu St. Mary’s Hospital, 65-1 Geumo-dong, Uijeongbu, Gyeonggi-do, 480-717, secondary stability is provided by the healing process South Korea; e-mail, [email protected] or [email protected]. of the surrounding tissue. Primary stability is important Submitted, April 2007; revised and accepted, June 2007. to minimize the potential for failure from micromotion. 0889-5406/$36.00 Copyright Ó 2010 by the American Association of Orthodontists. Secondary stability is related to the microstructure of 8-11 doi:10.1016/j.ajodo.2007.06.023 the implant surface. In conventional dental 135 136 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

Fig 1. Two-part design of the C-implant. Fig 2. Schematic illustration of the C-implant depen- dent on mandibular distalization mechanics. prosthetic implants, implants with a rough surface velop between the anterior teeth. To retract the anterior showed better stability and tissue reactions than did teeth with en-masse retraction, closing loops are placed those with a smooth surface. In orthodontic implants, between the lateral incisors and canines, and connected porous-surfaced implants show higher marginal bone to the C-implants by elastics. Because intermaxillary levels and less relative implant displacement than elastics are not applied to the maxillary dentition, threaded implants.12,13 mesial movement of the maxillary arch and extrusion The C-implant (CIMPLANT Company, Seoul, Ko- of the maxillary molars are avoided, and the incisors rea) was developed to use osseointegration as the are not flared. This case report describes the distaliza- main stabilizing mechanism.14-17 This mini-implant tion of the mandibular dentition to treat a dental has an upper abutment head component and a lower Class III malocclusion with a deviated midline by using threaded body or screw-type component (Fig 1). The C-implants. unique head design makes it possible to apply multiple elastics while simultaneously preventing the elastics from slipping off.15,16 The body or retentive component DIAGNOSIS of the C-implant is better able to resist the rotational ten- The patient was a woman, aged 23 years 5 months, dency of heavy dynamic loads and control 3-dimen- whose chief concern was protruding mandibular teeth. sional tooth movement as a result of its higher Her medical history was noncontributory, and occa- osseointegration potential. sional clicking of her temporomandibular joints (TMJ) When distalizing the mandibular dentition with was noted in her dental history. a mandibular C-implant, the most important consider- The pretreatment facial photographs (Fig 3) show an ation is its position. The placement site should be as acceptable facial profile, despite mild midface defi- close as possible to the mesial surface of the mandibular ciency and slight mandibular . No facial first molar because this will help achieve optimal distal- asymmetry was noticeable in the frontal view. The clin- ization of the mandibular dentition. The initial tooth ical examination (Figs 3 and 4) showed a Class III molar movement in distalization is posterior movement of and canine relationship that was more significant on the the second molar by using a sliding jig that is connected right side. Other findings included an anterior edge- to the main archwire, followed by moving the other to-edge relationship, a midline discrepancy, mild man- teeth posteriorly (Fig 2). While the second molar is dis- dibular anterior crowding, and mesial angulation of talizing, the first molar also moves distally as a result of the mandibular posterior teeth. The lower midline was drifting. When is complete, the pre- not coincident with the facial midline and was shifted molars will also begin to move with the sliding jig. to the left by 2.5 mm. The maxillary third molars and While the premolars are distalizing, spaces might de- the mandibular right third molar were missing American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 137 Volume 137, Number 1

Fig 3. Pretreatment extraoral and intraoral photographs.

(Fig 5A). There was only slight contact between the patient did not want extractions (except for the third maxillary right second molar and the opposing tooth be- molars) or changes to her facial appearance; she wanted cause of the Class III molar relationship. only to correct the incisor relationship. Although the The (Fig 5B; Table) showed maxillary incisors were slightly upright, the patient re- a skeletal Class III relationship with a high mandibular quested that they not be allowed to move forward. plane angle and a slightly retrognathic maxilla. The an- Therefore, we rejected the premolar-extraction treat- terior facial height was slightly long relative to the pos- ment option. terior facial height. The incisor position and interincisal Based on the initial records and the patient’s desires, relationship were within normal limits except for the the treatment objectives were to distalize all mandibular retroclined maxillary incisor. The patient was diagnosed teeth, improve the interincisal relationship to have nor- with a skeletal Class I malocclusion with mild maxillary mal overjet and overbite, shift the mandibular midline to deficiency and a dental Class III relationship. coincide with the facial and maxillary midlines, and achieve Class I canine and molar intercuspal relation- TREATMENT OBJECTIVES ships. A conventional fixed appliance was prescribed. A mandibular premolar extraction plan would be a relatively simple and stable way to resolve the anterior TREATMENT ALTERNATIVES . Complex treatment mechanics and many Maxillary advancement surgery was not a viable tooth movements would not be needed. However, the treatment option because the skeletal deficiency was 138 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

Fig 4. Pretreatment dental casts.

not significant, and the patient was pleased with her facial appearance. Maximum anchorage and interarch elastics were discussed for en-masse movement of the mandibular dentition. She refused the interarch elastics because of their visibility. Her occasional clicking was also a matter of concern because it might lead to TMJ dysfunction symptoms during orthodontic treatment. Therefore, mandibular distalization with a C-implant in the posterior dentition and intra-arch elastics was the treatment of choice. After distal movement of the mandibular dentition, a full fixed appliance would be used in the maxillary dentition for finishing.

TREATMENT PROGRESS Two C-implants, 1.8 mm in diameter and 8.5 mm long, were placed in the interdental spaces between the mandibular second premolars and first molars. Bone quality in the mandible was good, and the im- plants were loaded immediately. A 0.016-in NiTi initial archwire was used for leveling and distalization of the mandibular posterior dentition. Intra-arch elastics (1/4-in, 3.5 oz) were applied from the 0.7-mm-diameter stainless steel sliding jig to the neck of the C-implant for Fig 5. Pretreatment radiographs: A, panoramic; B, distalization of the mandibular second molar and ante- cephalometric. rior decrowding (Fig 6A). American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 139 Volume 137, Number 1

Table. Cephalometric measurements

Measurement Average (women)* Pretreatment Posttreatment

SNA () 81.6 77 76.5 SNB () 79.2 76.5 76 ANB difference () 2.4 0.5 0.5 PFH/AFH (%) 85.1/127.4 (66.8) 88.5/137 (64.6) 91/140.5 (64.8) SN-OP () 17.9 20.6 18 FH-U1 () 116.0 109.5 110 FMA () 24.3 33 33.5 IMPA () 95.9 91 80 FMIA () 59.8 56 66.5 UL-E plane (mm) À0.9 À1.5 À1 LL-E plane (mm) 0.6 1 0.5 Interincisal angle 123.8 127.5 136.5 Mx 1-NA (mm) 7.3 7 7.5 Mx 1-NA () 25.3 24 26 Mn 1-NB (mm) 7.9 8 4.5 Mn 1-NB () 28.4 27.3 17 SN-PP () 10.2 9.5 9.5

*For Korean women, data from, Korean Association of Orthodontists.31

Fig 6. Progress photographs: A, mandibular second molar distalization with 0.7-mm diameter stain- less steel sliding jig; B, power chain between C-implants and mandibular anterior teeth for retraction and midline correction.

The maxillary dentition was not bonded initially be- the incisors to the apically placed C-implant. To correct cause the dental and facial midlines were coincident, the anterior open-bite tendency from the force direction and no forward movement of the anterior teeth was de- of the elastics, the mandibular archwire was changed to sired. While the mandibular dentition was distalizing, a 0.016 3 0.022-in NiTi archwire and then a 0.016 3 drifting occurred. Therefore, a power chain was applied 0.022-in stainless steel archwire with closing loops to correct the midline (Fig 6B). This applied an intrusive (Fig 7). movement to the mandibular incisors because the NiTi As the mandibular molars moved distally, the max- archwire was not stiff, and elastics were applied from illary molars were extruded. To correct the extrusion, 140 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

Fig 7. Progress photographs of 0.016 3 0.022-in stainless steel archwire with closing loop applied to the mandibular dentition with a sliding jig to the mandibular right first molar activated for molar relationship improvement.

Fig 8. Progress photographs of the mandibular right second premolar distalized by the sliding jig and mandibular en-masse retraction with C-implants. the maxillary dentition was bonded for intrusion and continued to move separately (Fig 8). The closing leveling of the maxillary molars. A Class I molar rela- loop of the 0.016 3 0.022-in stainless steel archwire tionship of the mandibular left dentition was achieved was used as a hook for mandibular en-masse retraction. by using a sliding jig. The mandibular right dentition Distalization of the mandibular dentition and midline was distalized 6 mm but still required further move- correction took 18 months. The fixed appliances were ment. The sliding jig was continuously applied to the removed, and retention was provided by maxillary and mandibular first molar. The mandibular premolars mandibular fixed retainers. American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 141 Volume 137, Number 1

Fig 9. Posttreatment extraoral and intraoral photographs.

TREATMENT RESULTS The patient was pleased with the treatment results. The active treatment period was 18 months. The An ideal incisor relationship and Class I canine and patient’s facial profile was mostly unchanged (Fig 9). molar relationship were obtained. All radiographic A Class I canine and molar relationship and normal (Fig 12) and clinical measurements were within accept- tooth alignment with better midline coincidence, able limits. Lingual bonded retainers and wrap-around and normal overjet and overbite were achieved retainers were placed. Intraoral photographs after 8 (Figs 9 and 10). The maxillary incisors moved for- months of retention (Fig 13) showed substantial relapse ward slightly. The mandibular incisors were retracted on the right side back to Class III molar and canine considerably and extruded. The upper and lower lips relationships and a shallow overbite. We asked the pa- moved very little. The interincisal angle increased as tient to wear the wraparound more, and after the mandibular incisors uprighted and the ANB angle 26 months of retention, the occlusal relationship was remained unchanged. The posterior facial height- stable (Fig 14). anterior facial height ratio and the FMA were only slightly changed in spite of the significant mandibu- DISCUSSION lar molar distalization as seen in the superimposition The entire mandibular dentition was distalized with (Fig 11). intra-arch elastics and a supporting C-implant between 142 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

Fig 10. Posttreatment dental casts.

Fig 11. Cephalometric superimposition. Black, pretreatment; gray, posttreatment. the second premolars and first molars bilaterally and spacing was closed rapidly by using elastomeric chain without extrusion or forward movement of the maxil- from the C-implant. The implant site was based on cor- lary dentition. Mandibular posterior distalization began tical bone thickness, anatomic structures, and soft-tissue with a NiTi wire for anterior decrowding and midline functional movements. Most reports suggest that the correction. After distalization and decrowding, anterior preferred site for arch distalization with skeletal American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 143 Volume 137, Number 1

stability,19,20 but this site is not recommended because of tissue irritation during mastication.21 Thus, the alveolar bone between the second premolar and the first molar might be a good choice for minimum discomfort and maximum stability. The mental foramen and man- dibular canal can be avoided if the implant is placed not too far from the apex of the adjacent teeth.21 We reviewed computed-tomography studies of interradicular space to prevent root damage.20,22 Park20 evaluated the computed tomography images and reported bone thicknesses and distances between roots 5 to 7 mm apical to the alveolar crest. The average distance between the roots of the mandibular second premolar and first molar was 3.47 mm (range, 2.0-4.8 mm). The distance between the roots of the mandibular first and second molars was 4.57 mm (range, 2.7-6.5 mm). Park et al21 found smaller distances of 2.4 to 3.3 mm between the second premolar and the first mo- lar, and 2.8 to 3.7 mm between the first and second mo- lars. The distances from the cortical bone surface to the interradicular space however, were relatively larger (3.7-4.2 and 5.3-7.0 mm, respectively). It follows that orthodontic implants 1.8 mm in diameter can be placed at a slight angle of inclination relative to the buccal cor- tical bone to overcome the limitation of minimum inter- radicular space. Fig 12. Posttreatment radiographs: A, panoramic; B, The amounts of distal tooth movement have been 23 cephalometric. reported previously. Saito et al reported 1.8 to 10.7 mm of tooth movement in a dog study. In another report, the average amounts of distalization of the man- dibular first molars were 3.5 mm at the crown level and anchorage is the terminal molar.18,19 The retromolar 1.8 mm at the root level. The average amount of relapse area has been reported as an optimal placement site, of- was 0.3 mm at both the crown and root apex levels.6 In fering a relatively thick cortical bone layer in the man- a recent case report, the mandibular dentition was distal- dible.18,19 However, soft-tissue problems can occur ized 5 and 2 mm on the left and right sides, respec- around the screw implants because the soft tissue is usu- tively.16 In another case report, the mandibular ally thicker and more movable in the retromolar area posterior teeth were distalized 6 and 4 mm on the right than in other areas.7 This can result in inflammation, and left sides, respectively.24 patient discomfort, and difficulty applying elastics or As seen in the treatment results reported here, distal- NiTi coil springs. ization of the entire mandibular dentition was accompa- Alternative sites for posterior anchorage are the nied by a slight mandibular posterior extrusion, which is edentulous areas of the alveolar process and posterior not problematic in brachyfacial patients. However, in alveolar bone.19,20 Therefore, the alveolar bone around severe dolichofacial patients, intrusion of posterior teeth the posterior teeth can be the site of choice in patients would be desirable, since counterclockwise mandibular without edentulous areas. Miniscrews can be placed rotation leads to more esthetic results. Maxillary poste- between the roots of the posterior teeth without damag- rior C-implants and interarch elastics might be good ing the roots, because the cortical bone in these areas is choices in such cases.16 Interarch elastics induce man- not very thin.20 dibular posterior intrusion by tip-back mechanics, Orthodontic mini-implants can be placed either instead of extrusion. Maxillary C-implants can also be between the first and second molars or between the sec- used as anchorage for additional maxillary posterior ond premolar and the first molar in the mandibular arch. intrusion. This allows selection of specific treatment The thickness of the cortical bone between the first mechanics for distalization based on the skeletal and and second molars is enough to provide primary facial pattern of patients. 144 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

Fig 13. Retention intraoral photographs at 8 months.

Fig 14. Retention intraoral photographs at 26 months.

Another issue of concern is the relationship between animals.28 Although the exact cause of TMD is not interarch elastics and temporomandibular disorders completely understood, loading is at least considered (TMD). According to a previous report, Class II a possible etiologic causes. Therefore, it might be pru- interarch elastics were not related to TMD.25 However, dent to create a treatment plan that minimizes condylar Class III elastic usage in patients with subclinical TMD loading in patients with potential TMD problems. problems needs more careful consideration. Some A final issue of concern is the relationship between authors suggested that a posteriorly positioned condyle the long-term retention results and the entire dentition is a common predisposing factor in anterior TMJ distalization method. We recommended the fixed disc displacement.26,27 It has also been reported that retainer and wraparound retainer combined retention interarch force might be an etiologic factor of TMD in method to the patient and also encouraged her to chew American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 145 Volume 137, Number 1 on both sides after treatment. However, she accepted We thank Jae-Hee Cho for assisting with manuscript only the fixed retainers. Eight months after debonding, preparation. significant relapse on the right side was observed. The relapse tendency was assumed to be due to severe tip- REFERENCES ping of the mandibular molar distally, as can be seen 1. Proffit WR. Interarch elastics: their place in modern orthodontics. in the cephalometric radiograph, and also to insufficient In: Ho¨sl E, Baldauf A, editors. Mechanical and biological basics retention and habitual mastication on left side. Merri- in orthodontic therapy. Huthig Buchverlag GmbH, Heidelberg, 29 field defined directional forces as those that use direc- Germany: 1991. p. 173-8. tional control to precisely position the teeth, and Lima 2. Roberts WE, Smith RK, Zilberman Y, Mozsary PG, Smith RS. and Lima30 showed 4 years of stable retention after Osseous adaptation to continuous loading of endosseous implants. Am J Orthod Dentofacial Orthop 1984;86:95-111. mandibular dentition distalization treatment in a case 3. Roberts WE, Helm FR, Marchall KJ, Gongloff RK. Rigid endo- report. sseous implants for orthodontic anchorage and orthopedic anchor- If the mandibular molars in our patient were age. Angle Orthod 1989;59:247-56. controlled bodily by additional loop mechanics after 4. Higuchi KW, Slack JM. The use of titanium fixtures for intraoral tip-back movement, a more stable result was possible. anchorage to facilitate orthodontic tooth movement. Int J Oral Maxillofac Implants 1991;6:338-44. The sliding jig application on a stiffer archwire would 5. Umemori M, Sugawara J, Mitani H, Nagasaka H, Kawamura H. be better than only tip-back treatment methods for Skeletal anchorage system for open-bite correction. Am J Orthod bodily distalization of molars. On the contrary, the Dentofacial Orthop 1999;115:166-74. distalized mandibular left dentition showed more stable 6. Sugawara J, Daimaruya T, Umemori M, Nagasaka H, Takahashi I, retention compared with the right dentition. It was Kawamura H, et al. Distal movement of mandibular molars in adult patients with the skeletal anchorage system. Am J Orthod assumed that second molar distalizing began a week Dentofacial Orthop 2004;125:130-8. after the mandibular left third molar extraction, and 7. Park HS, Lee SK, Kwon OW.Group distal movement of teeth using the bodily tooth movement was possible because of rel- microscrew implant anchorage. Angle Orthod 2005;75:602-9. atively low cortical resistance on that side. Maxillary 8. Wehrbein H, Glatzmaier J, Yildirim M. Orthodontic anchorage and mandibular wraparound retainers were used in capacity of short titanium screw implants in the maxilla. An experi- mental study in the dog. Clin Oral Implants Res 1997;8:131-41. this patient in that period, and she had a recall check 3 9. De Pauw GA, Dermaut L, De Bruyn H, Johansson C. Stability of months later. After 26 months of retention, the patient implants as anchorage for orthopedic traction. Angle Orthod did not show a significant relapse tendency as she had 1999;69:401-7. after 8 months of retention (Fig 14). 10. Gotfredsen K, Berglundh T, Lindhe J. Bone reactions adjacent to Mandibular premolar extraction without moving titanium implants subjected to static load. A study in the dog (I). Clin Oral Implants Res 2001;12:1-8. molars distally would perhaps have led to a more stable 11. Gotfredsen K, Berglundh T, Lindhe J. Bone reactions adjacent to result. Despite the patient’s request, we should have titanium implants with different surface characteristics subjected persuaded her to select this simpler treatment option. to static load. A study in the dog (II). Clin Oral Implants Res 2001; However, the tip-back tooth movement and long-term 12:196-201. retention results of this patient will be helpful for clini- 12. Oyonarte R, Pillar RM, Deporter D, Woodside DG. Peri-implant bone response to orthodontic loading: part 1. A histomorphomet- cians who consider similar treatment mechanics for ric study of the effects of implant surface design. Am J Orthod patients with Class III anterior crossbite. Dentofacial Orthop 2005;128:173-81. In cases of whole-dentition distalization, we recom- 13. Oyonarte R, Pillar RM, Deporter D, Woodside DG. Peri-implant mend both a wraparound removable retainer and a fixed bone response to orthodontic loading: part 2. Implant surface retainer, and that chewing be done on both sides. Class geometry and its effect on regional bone remodeling. Am J Orthod Dentofacial Orthop 2005;128:182-9. III intermaxillary elastics applied to a splint-type 14. Chung KR, Kim SH, Kook YA. The C-orthodontic micro-implant. retainer with hooks for night wear can be a good alter- J Clin Orthod 2004;38:478-86. native to conventional retention methods. 15. Chung KR, Nelson G, Kim SH, Kook YA. Severe bidentoalveolar protrusion treated with orthodontic microimplant-dependent en- masse retraction. Am J Orthod Dentofacial Orthop 2007;132: CONCLUSIONS 105-15. 16. Chung KR, Kim SH, Kook YA. C-orthodontic microimplant for The C-implant can withstand heavier loads than distalization of mandibular dentition in Class III correction. Angle other skeletal anchorage systems. It also has the advan- Orthod 2005;75:119-28. tage that its abutment head design can be used for elastic 17. Jeon MS, Kang YG, Mo SS, Lee KH, Kook YA, Kim SH. Effects applications. In this case, the C-implant and multiple of surface treatment on the osseointegration potential of orthodon- tic mini-implant. Korean J Orthod 2008;38:328-36. intra-arch elastics distalized the entire mandibular 18. Kim JH, Joo JY, Park YW, Cha BK, Kim SM. Study of maxillary dentition independently, without extrusion or flaring cortical bone thickness for skeletal anchorage system in Korean. of the maxillary dentition. J Kor Oral Maxillofac Surg 2002;28:249-55. 146 Chung et al American Journal of Orthodontics and Dentofacial Orthopedics January 2010

19. Costa A, Raffaini M, Melsen B. Miniscrews as orthodontic prospective study. Am J Orthod Dentofacial Orthop 1993;103: anchorage: a preliminary report. Int J Adult Orthod Orthognath 459-63. Surg 1998;13:201-9. 26. Farrar WB, McCarty WL. A clinical outline of temporomandibu- 20. Park HS. An anatomical study using CT images for the im- lar joint diagnosis and treatment. Montgomery, Ala: Walker Print- plantation of micro-implants. Korean J Orthod 2002;32: ing; 1983. p. 84-5. 435-41. 27. Wyatt WE. Preventing adverse effects on the temporomandibular 21. Park YC, Kim JK, Lee JS. Atlas of contemporary orthodontics. joint through orthodontic treatment. Am J Orthod Dentofacial Vol. III. Seoul, Korea: Sinheung; 2005. p. 178-93. Orthop 1987;91:493-9. 22. Carano A, Velo S, Incorvati C, Poggio P. Clinical applications of 28. Fujimura K, Kobayashi S, Suzuki T, Segami N. Histologic evalu- the mini-screw anchorage system (M.A.S) in the maxillary alve- ation of temporomandibular arthritis induced by mild mechanical olar bone. Prog Orthod 2004;5:212-30. loading in rabbits. J Oral Pathod Med 2005;34:157-63. 23. Saito S, Sugimoto N, Morohashi T, Ozeki M, Kurabayashi H, 29. Merrifield LL. Differential diagnosis. Semin Orthod 1996;2: Shimizu H, et al. Endosseous titanium implants as anchors for 241-53. mesiodistal tooth movement in the beagle dog. Am J Orthod Den- 30. Lima CEO, Lima MTO. Directional force treatment for an adult tofacial Orthop 2000;118:601-7. with Class III malocclusion and open bite. Am J Orthod Dentofa- 24. Park HS, Kwon TG, Sung JH. Nonextraction treatment with cial Orthop 2006;129:817-24. microscrew implants. Angle Orthod 2004;74:539-49. 31. Korean Association of Orthodontists. Cephalometric norm of 25. O’Reilly MT, Rinchuse DJ, Close J. Class II elastics and Korean adults with normal occlusion. Korea: Ji-Sung Publishing extractions and temporomandibular disorders: a longitudinal Co.; 1998. p. 589-95.