distalizacion de arcada

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CASE REPORT Distalization of the mandibular dentition with mini-implants to correct a Class III malocclusion with a midline deviation Kyu-Rhim Chung, a Seong-Hun Kim, b HyeRan Choo, c Yoon-Ah Kook, d and Jason B. Cope e 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 anchorage for Class I intra-arch elastics. 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 overbite and overjet were obtained, and facial balance was improved. (Am J Orthod Dentofacial Orthop 2010;137:135-46) E very orthodontic tooth movement is accompa- nied by a reaction. This can make it difficult to correct a malocclusion by using intraoral appli- ances alone, especially when complete distal movement of the mandibular dentition is planned in nonsurgical Class III malocclusion treatment. Traditionally, fixed ap- pliances and intermaxillary elastics have been used to move mandibular molars distally, often resulting in un- desirable proclination of the maxillary incisors and ex- trusion of the maxillary molars as reciprocal side effects. 1 This can cause an esthetic problem and instabil- ity, especially in long-faced adults. Also, because inter- maxillary elastic wear requires patient compliance, it is difficult to predict the final result in uncooperative patients. Therefore, several authors have attempted to treat this type of malocclusion by distal tooth movement alone. For example, animal studies and clinical investi- gations have used conventional implants as absolute anchorage 2-4 and miniplates for intrusion or distalization of the mandibular posterior teeth. 5,6 Because all portions of the anchor plates and screws were placed outside the dentition in these studies, it was possible to move the mandibular molars without disturbing tooth movement. Recently, the mechanics of group distal movement of teeth with microscrew implant anchorage was intro- duced. 7 A distalizing force is applied to the canines through a nickel-titanium (NiTi) coil spring connecting the miniscrew to hooks on the archwire. The primary treatment effect in the mandible is distal tipping move- ment of the posterior teeth concurrent with uprighting and distal movement of the anterior teeth. Because there is no force to move the maxillary anterior teeth forward (via Class III elastics), there are no side effects on the maxillary anterior teeth in microscrew implant-aided mechanics. Therefore, distal movement assisted by a rigid orthodontic implant can be a good alternative for treatment when intermaxillary elastics are not indi- cated or the patient is uncooperative. The stability of temporary skeletal anchorage devices is achieved from primary mechanical retention between the implant surface and the cortical bone, and secondary stability is provided by the healing process of the surrounding tissue. Primary stability is important to minimize the potential for failure from micromotion. Secondary stability is related to the microstructure of the implant surface. 8-11 In conventional dental a President, Korean Society of Speedy Orthodontics, Seoul, Korea. b Assistant professor, Department of Orthodontics, Catholic University of Korea, Uijongbu St. Mary’s Hospital, Uijongbu, Korea. c Attending orthodontist, The Children’s Hospital of Philadelphia; clinical asso- ciate, University of Pennsylvania School of Dental Medicine, Philadelphia, Pa. d Professor and chairman, Department of Orthodontics, Catholic University of Korea, Seoul St. Mary’s Hospital, Seoul, Korea. e Adjunct clinical assistant professor, Department of Orthodontics; adjunct assistant professor, Department of Oral and Maxillofacial Surgery, Baylor College of Dentistry, Dallas, Tex. Partly supported by the Korean Society of Speedy Orthodontics, the alumni fund of the Department of Dentistry, and the Graduate School of Clinical Dental Sci- ence, Catholic University of Korea. The authors report no commercial, proprietary, or financial interest in the prod- ucts or companies described in this article. Reprint requests to: Seong-Hun Kim, Catholic University of Korea, Uijongbu St. Mary’s Hospital, 65-1 Geumo-dong, Uijeongbu, Gyeonggi-do, 480-717, South Korea; e-mail, [email protected] or [email protected]. Submitted, April 2007; revised and accepted, June 2007. 0889-5406/$36.00 Copyright Ó 2010 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2007.06.023 135

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  • CASE REPORT

    Distalization of the mandmini-implants to correct awith a midline deviation

    Kyu-Rhim Chung,a Seong-Hun Kim,b HyeRan Choo,c Yoo

    Uijongbu and Seoul, Korea, Philadelphia, Pa, and Dallas, Tex

    This article describes the orthodontic treatment for a young wmalocclusion and a deviated midline. Two orthodontic minSeoul, Korea) were placed in the interdental spaces betweenlars. The treatment plan consisted of distalizing the mandibulfor en-masse retraction of the mandibular anterior teeth. C-im

    lantationd ov5-46

    Recently, the mechanics of group distal movementof teeth with microscrew implant anchorage was intro-

    caninesnectingprimarymove-

    rightingse thereforwards on the

    maxillary anterior teeth in microscrew implant-aided

    for treatment when intermaxillary elastics are not indi-

    Secondary stability is related to the microstructure ofthe implant surface.8-11 In conventional dental

    Professor and chairman, Department of Orthodontics, Catholic University of

    College of Dentistry, Dallas, Tex.

    0889-5406/$36.00

    Copyright 2010 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2007.06.023135cated or the patient is uncooperative.The stability of temporary skeletal anchorage

    devices is achieved from primary mechanical retentionbetween the implant surface and the cortical bone, andsecondary stability is provided by the healing processof the surrounding tissue. Primary stability is importantto minimize the potential for failure from micromotion.

    Partly supported by the Korean Society of Speedy Orthodontics, the alumni fund

    of the Department of Dentistry, and the Graduate School of Clinical Dental Sci-

    ence, Catholic University of Korea.

    The authors report no commercial, proprietary, or financial interest in the prod-

    ucts or companies described in this article.

    Reprint requests to: Seong-Hun Kim, Catholic University of Korea, Uijongbu

    St. Marys Hospital, 65-1 Geumo-dong, Uijeongbu, Gyeonggi-do, 480-717,

    South Korea; e-mail, [email protected] or [email protected].

    Submitted, April 2007; revised and accepted, June 2007.mechanics. Therefore, distal movement assisted bya rigid orthodontic implant can be a good alternative

    Korea, Seoul St. Marys Hospital, Seoul, Korea.eAdjunct clinical assistant professor, Department of Orthodontics; adjunct

    assistant professor, Department of Oral and Maxillofacial Surgery, Baylority, especially in long-faced adults. Also, because inter-maxillary elastic wear requires patient compliance, it isdifficult to predict the final result in uncooperative

    duced.7 A distalizing force is applied to thethrough a nickel-titanium (NiTi) coil spring conthe miniscrew to hooks on the archwire. Thetreatment effect in the mandible is distal tippingment of the posterior teeth concurrent with upand distal movement of the anterior teeth. Becauis no force to move the maxillary anterior teeth(via Class III elastics), there are no side effect

    aPresident, Korean Society of Speedy Orthodontics, Seoul, Korea.bAssistant professor, Department of Orthodontics, Catholic University of

    Korea, Uijongbu St. Marys Hospital, Uijongbu, Korea.cAttending orthodontist, The Childrens Hospital of Philadelphia; clinical asso-

    ciate, University of Pennsylvania School of Dental Medicine, Philadelphia, Pa.dClass I intra-arch elastics. The head design of the C-imptreatment. Sliding jigs were applied buccally for distaliztreatment period was 18 months. Normal overbite animproved. (Am J Orthod Dentofacial Orthop 2010;137:13

    Every orthodontic tooth movement is accompa-nied by a reaction. This can make it difficult tocorrect a malocclusion by using intraoral appli-

    ances alone, especially when complete distal movementof the mandibular dentition is planned in nonsurgicalClass IIImalocclusion treatment. Traditionally, fixed ap-pliances and intermaxillary elastics have been used tomove mandibular molars distally, often resulting in un-desirable proclination of the maxillary incisors and ex-trusion of the maxillary molars as reciprocal sideeffects.1 This can cause an esthetic problem and instabil-ibular dentition withClass III malocclusion

    n-Ah Kook,d and Jason B. Copee

    oman, aged 23 years 5 months, with a Class IIIi-implants (C-implants, CIMPLANT Company,the mandibular second premolars and first mo-ar dentition asymmetrically and creating spaceplants were placed to provide anchorage for

    minimizes gingival irritation during orthodonticof the mandibular posterior teeth. The activeerjet were obtained, and facial balance was)

    patients. Therefore, several authors have attempted totreat this type of malocclusion by distal tooth movementalone. For example, animal studies and clinical investi-gations have used conventional implants as absoluteanchorage2-4 andminiplates for intrusion or distalizationof themandibular posterior teeth.5,6 Because all portionsof the anchor plates and screws were placed outside thedentition in these studies, it was possible to move themandibular molars without disturbing tooth movement.

  • 136 Chung et al American Journal of Orthodontics and Dentofacial Orthopedicsprosthetic implants, implants with a rough surfaceshowed better stability and tissue reactions than didthose with a smooth surface. In orthodontic implants,porous-surfaced implants show higher marginal bonelevels and less relative implant displacement thanthreaded implants.12,13

    The C-implant (CIMPLANT Company, Seoul, Ko-rea) was developed to use osseointegration as themain stabilizing mechanism.14-17 This mini-implant

    Fig 1. Two-part design of the C-implant.has an upper abutment head component and a lowerthreaded body or screw-type component (Fig 1). Theunique head design makes it possible to apply multipleelastics while simultaneously preventing the elasticsfrom slipping off.15,16 The body or retentive componentof the C-implant is better able to resist the rotational ten-dency of heavy dynamic loads and control 3-dimen-sional tooth movement as a result of its higherosseointegration potential.

    When distalizing the mandibular dentition witha mandibular C-implant, the most important consider-ation is its position. The placement site should be asclose as possible to the mesial surface of the mandibularfirst molar because this will help achieve optimal distal-ization of the mandibular dentition. The initial toothmovement in distalization is posterior movement ofthe second molar by using a sliding jig that is connectedto the main archwire, followed by moving the otherteeth posteriorly (Fig 2). While the second molar is dis-talizing, the first molar also moves distally as a result ofdrifting. When molar distalization is complete, the pre-molars will also begin to move with the sliding jig.While the premolars are distalizing, spaces might de-velop between the anterior teeth. To retract the anteriorteeth with en-masse retraction, closing loops are placedbetween the lateral incisors and canines, and connectedto the C-implants by elastics. Because intermaxillaryelastics are not applied to the maxillary dentition,mesial movement of the maxillary arch and extrusionof the maxillary molars are avoided, and the incisorsare not flared. This case report describes the distaliza-tion of the mandibular dentition to treat a dental

    Fig 2. Schematic illustration of the C-implant depen-dent on mandibular distalization mechanics.January 2010Class III malocclusion with a deviated midline by usingC-implants.

    DIAGNOSIS

    The patient was a woman, aged 23 years 5 months,whose chief concern was protruding mandibular teeth.Her medical history was noncontributory, and occa-sional clicking of her temporomandibular joints (TMJ)was noted in her dental history.

    The pretreatment facial photographs (Fig 3) show anacceptable facial profile, despite mild midface defi-ciency and slight mandibular prognathism. No facialasymmetry was noticeable in the frontal view. The clin-ical examination (Figs 3 and 4) showed a Class III molarand canine relationship that was more significant on theright side. Other findings included an anterior edge-to-edge relationship, a midline discrepancy, mild man-dibular anterior crowding, and mesial angulation ofthe mandibular posterior teeth. The lower midline wasnot coincident with the facial midline and was shiftedto the left by 2.5 mm. The maxillary third molars andthe mandibular right third molar were missing

  • American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 137

    Volume 137, Number 1(Fig 5A). There was only slight contact between themaxillary right second molar and the opposing tooth be-cause of the Class III molar relationship.

    The cephalometric analysis (Fig 5B; Table) showeda skeletal Class III relationship with a high mandibularplane angle and a slightly retrognathic maxilla. The an-terior facial height was slightly long relative to the pos-terior facial height. The incisor position and interincisalrelationship were within normal limits except for theretroclined maxillary incisor. The patient was diagnosedwith a skeletal Class I malocclusion with mild maxillarydeficiency and a dental Class III relationship.

    TREATMENT OBJECTIVES

    A mandibular premolar extraction plan would bea relatively simple and stable way to resolve the anteriorcrossbite. Complex treatment mechanics and manytooth movements would not be needed. However, the

    Fig 3. Pretreatment extraoral apatient did not want extractions (except for the thirdmolars) or changes to her facial appearance; she wantedonly to correct the incisor relationship. Although themaxillary incisors were slightly upright, the patient re-quested that they not be allowed to move forward.Therefore, we rejected the premolar-extraction treat-ment option.

    Based on the initial records and the patients desires,the treatment objectives were to distalize all mandibularteeth, improve the interincisal relationship to have nor-mal overjet and overbite, shift the mandibular midline tocoincide with the facial and maxillary midlines, andachieve Class I canine and molar intercuspal relation-ships. A conventional fixed appliance was prescribed.

    TREATMENT ALTERNATIVES

    Maxillary advancement surgery was not a viabletreatment option because the skeletal deficiency was

    nd intraoral photographs.

  • Fig 4. Pretreatmen

    Fig 5. Pretreatment radiographs: A, panoramic; B,cephalometric.

    138 Chung et al American Journal of Orthodontics and Dentofacial Orthopedicst dental casts.January 2010not significant, and the patient was pleased with herfacial appearance. Maximum anchorage and interarchelastics were discussed for en-masse movement ofthe mandibular dentition. She refused the interarchelastics because of their visibility. Her occasionalclicking was also a matter of concern because it mightlead to TMJ dysfunction symptoms during orthodontictreatment. Therefore, mandibular distalization witha C-implant in the posterior dentition and intra-archelastics was the treatment of choice. After distalmovement of the mandibular dentition, a full fixedappliance would be used in the maxillary dentitionfor finishing.

    TREATMENT PROGRESS

    Two C-implants, 1.8 mm in diameter and 8.5 mmlong, were placed in the interdental spaces betweenthe 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 initialarchwire was used for leveling and distalization of themandibular posterior dentition. Intra-arch elastics(1/4-in, 3.5 oz) were applied from the 0.7-mm-diameterstainless steel sliding jig to the neck of the C-implant fordistalization of the mandibular second molar and ante-rior decrowding (Fig 6A).

  • American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 139Table. Cephalometric measurements

    Measurement Average (women)*

    SNA () 81.6SNB () 79.2ANB difference () 2.4

    Volume 137, Number 1The maxillary dentition was not bonded initially be-cause the dental and facial midlines were coincident,and no forward movement of the anterior teeth was de-sired. While the mandibular dentition was distalizing,drifting occurred. Therefore, a power chain was appliedto correct the midline (Fig 6B). This applied an intrusivemovement to the mandibular incisors because the NiTiarchwire was not stiff, and elastics were applied from

    PFH/AFH (%) 85.1/127.4 (66.8)

    SN-OP () 17.9FH-U1 () 116.0FMA () 24.3IMPA () 95.9FMIA () 59.8UL-E plane (mm) 0.9LL-E plane (mm) 0.6

    Interincisal angle 123.8

    Mx 1-NA (mm) 7.3

    Mx 1-NA () 25.3Mn 1-NB (mm) 7.9

    Mn 1-NB () 28.4SN-PP () 10.2

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

    Fig 6. Progress photographs: A,mandibular secondless steel sliding jig; B, power chain between C-implaand midline correction.Pretreatment Posttreatment

    77 76.5

    76.5 76

    0.5 0.5the incisors to the apically placed C-implant. To correctthe anterior open-bite tendency from the force directionof the elastics, the mandibular archwire was changed toa 0.016 3 0.022-in NiTi archwire and then a 0.016 30.022-in stainless steel archwire with closing loops(Fig 7).

    As the mandibular molars moved distally, the max-illary molars were extruded. To correct the extrusion,

    88.5/137 (64.6) 91/140.5 (64.8)

    20.6 18

    109.5 110

    33 33.5

    91 80

    56 66.5

    1.5 11 0.5

    127.5 136.5

    7 7.5

    24 26

    8 4.5

    27.3 17

    9.5 9.5

    molar distalization with 0.7-mm diameter stain-nts and mandibular anterior teeth for retraction

  • 140 Chung et al American Journal of Orthodontics and Dentofacial Orthopedicsthe maxillary dentition was bonded for intrusion andleveling of the maxillary molars. A Class I molar rela-tionship of the mandibular left dentition was achievedby using a sliding jig. The mandibular right dentitionwas distalized 6 mm but still required further move-ment. The sliding jig was continuously applied to themandibular first molar. The mandibular premolars

    Fig 7. Progress photographs of 0.016 3 0.022-in stto the mandibular dentition with a sliding jig to the mrelationship improvement.

    Fig 8. Progress photographs of themandibular rightmandibular en-masse retraction with C-implants.January 2010continued to move separately (Fig 8). The closingloop of the 0.016 3 0.022-in stainless steel archwirewas used as a hook for mandibular en-masse retraction.Distalization of the mandibular dentition and midlinecorrection took 18 months. The fixed appliances wereremoved, and retention was provided by maxillary andmandibular fixed retainers.

    ainless steel archwire with closing loop appliedandibular right first molar activated for molar

    second premolar distalized by the sliding jig and

  • American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 141

    Volume 137, Number 1TREATMENT RESULTS

    The active treatment period was 18 months. Thepatients facial profile was mostly unchanged (Fig 9).A Class I canine and molar relationship and normaltooth alignment with better midline coincidence,and normal overjet and overbite were achieved(Figs 9 and 10). The maxillary incisors moved for-ward slightly. The mandibular incisors were retractedconsiderably and extruded. The upper and lower lipsmoved very little. The interincisal angle increased asthe mandibular incisors uprighted and the ANB angleremained unchanged. The posterior facial height-anterior facial height ratio and the FMA were onlyslightly changed in spite of the significant mandibu-lar molar distalization as seen in the superimposition(Fig 11).

    Fig 9. Posttreatment extraoral aThe patient was pleased with the treatment results.An ideal incisor relationship and Class I canine andmolar relationship were obtained. All radiographic(Fig 12) and clinical measurements were within accept-able limits. Lingual bonded retainers and wrap-aroundretainers were placed. Intraoral photographs after 8months of retention (Fig 13) showed substantial relapseon the right side back to Class III molar and caninerelationships and a shallow overbite. We asked the pa-tient to wear the wraparound retainer more, and after26 months of retention, the occlusal relationship wasstable (Fig 14).

    DISCUSSION

    The entire mandibular dentition was distalized withintra-arch elastics and a supporting C-implant between

    nd intraoral photographs.

  • 142 Chung et al American Journal of Orthodontics and Dentofacial Orthopedicsthe second premolars and first molars bilaterally andwithout extrusion or forward movement of the maxil-lary dentition. Mandibular posterior distalization beganwith a NiTi wire for anterior decrowding and midlinecorrection. After distalization and decrowding, anterior

    Fig 10. Posttreatme

    Fig 11. Cephalometric superimposition. BlaJanuary 2010spacing was closed rapidly by using elastomeric chainfrom the C-implant. The implant site was based on cor-tical bone thickness, anatomic structures, and soft-tissuefunctional movements. Most reports suggest that thepreferred site for arch distalization with skeletal

    nt dental casts.

    ck, pretreatment; gray, posttreatment.

  • American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 143

    Volume 137, Number 1anchorage is the terminal molar.18,19 The retromolararea has been reported as an optimal placement site, of-fering a relatively thick cortical bone layer in the man-dible.18,19 However, soft-tissue problems can occuraround the screw implants because the soft tissue is usu-ally thicker and more movable in the retromolar areathan in other areas.7 This can result in inflammation,patient discomfort, and difficulty applying elastics orNiTi coil springs.

    Alternative sites for posterior anchorage are theedentulous areas of the alveolar process and posterioralveolar bone.19,20 Therefore, the alveolar bone aroundthe posterior teeth can be the site of choice in patientswithout edentulous areas. Miniscrews can be placedbetween the roots of the posterior teeth without damag-ing the roots, because the cortical bone in these areas isnot very thin.20

    Orthodontic mini-implants can be placed eitherbetween the first and second molars or between the sec-ond premolar and the first molar in the mandibular arch.The thickness of the cortical bone between the firstand second molars is enough to provide primary

    Fig 12. Posttreatment radiographs: A, panoramic; B,cephalometric.stability,19,20 but this site is not recommended becauseof tissue irritation during mastication.21 Thus, thealveolar bone between the second premolar and the firstmolar might be a good choice for minimum discomfortand maximum stability. The mental foramen and man-dibular canal can be avoided if the implant is placednot too far from the apex of the adjacent teeth.21

    We reviewed computed-tomography studies ofinterradicular space to prevent root damage.20,22

    Park20 evaluated the computed tomography imagesand reported bone thicknesses and distances betweenroots 5 to 7 mm apical to the alveolar crest. The averagedistance between the roots of the mandibular secondpremolar and first molar was 3.47 mm (range, 2.0-4.8mm). The distance between the roots of the mandibularfirst and second molars was 4.57 mm (range, 2.7-6.5mm). Park et al21 found smaller distances of 2.4 to3.3 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 theinterradicular space however, were relatively larger(3.7-4.2 and 5.3-7.0 mm, respectively). It follows thatorthodontic implants 1.8 mm in diameter can be placedat a slight angle of inclination relative to the buccal cor-tical bone to overcome the limitation of minimum inter-radicular space.

    The amounts of distal tooth movement have beenreported previously. Saito et al23 reported 1.8 to10.7 mm of tooth movement in a dog study. In anotherreport, the average amounts of distalization of the man-dibular first molars were 3.5 mm at the crown level and1.8 mm at the root level. The average amount of relapsewas 0.3 mm at both the crown and root apex levels.6 Ina recent case report, the mandibular dentition was distal-ized 5 and 2 mm on the left and right sides, respec-tively.16 In another case report, the mandibularposterior teeth were distalized 6 and 4 mm on the rightand left sides, respectively.24

    As seen in the treatment results reported here, distal-ization of the entire mandibular dentition was accompa-nied by a slight mandibular posterior extrusion, which isnot problematic in brachyfacial patients. However, insevere dolichofacial patients, intrusion of posterior teethwould be desirable, since counterclockwise mandibularrotation leads to more esthetic results. Maxillary poste-rior C-implants and interarch elastics might be goodchoices in such cases.16 Interarch elastics induce man-dibular posterior intrusion by tip-back mechanics,instead of extrusion. Maxillary C-implants can also beused as anchorage for additional maxillary posteriorintrusion. This allows selection of specific treatment

    mechanics for distalization based on the skeletal andfacial pattern of patients.

  • 144 Chung et al American Journal of Orthodontics and Dentofacial OrthopedicsAnother issue of concern is the relationship betweeninterarch elastics and temporomandibular disorders(TMD). According to a previous report, Class IIinterarch elastics were not related to TMD.25 However,Class III elastic usage in patients with subclinical TMDproblems needs more careful consideration. Someauthors suggested that a posteriorly positioned condyleis a common predisposing factor in anterior TMJdisc displacement.26,27 It has also been reported thatinterarch force might be an etiologic factor of TMD in

    Fig 13. Retention intraoral ph

    Fig 14. Retention intraoral phJanuary 2010animals.28 Although the exact cause of TMD is notcompletely understood, loading is at least considereda possible etiologic causes. Therefore, it might be pru-dent to create a treatment plan that minimizes condylarloading in patients with potential TMD problems.

    A final issue of concern is the relationship betweenthe long-term retention results and the entire dentitiondistalization method. We recommended the fixedretainer and wraparound retainer combined retentionmethod to the patient and also encouraged her to chew

    otographs at 8 months.

    otographs at 26 months.

  • retention and habitual mastication on left side. Merri-29

    Orthod 2005;75:119-28.

    17. Jeon MS, Kang YG, Mo SS, Lee KH, Kook YA, Kim SH. Effects

    American Journal of Orthodontics and Dentofacial Orthopedics Chung et al 145field defined directional forces as those that use direc-tional control to precisely position the teeth, and Limaand Lima30 showed 4 years of stable retention aftermandibular dentition distalization treatment in a casereport.

    If the mandibular molars in our patient werecontrolled bodily by additional loop mechanics aftertip-back movement, a more stable result was possible.The sliding jig application on a stiffer archwire wouldbe better than only tip-back treatment methods forbodily distalization of molars. On the contrary, thedistalized mandibular left dentition showed more stableretention compared with the right dentition. It wasassumed that second molar distalizing began a weekafter the mandibular left third molar extraction, andthe bodily tooth movement was possible because of rel-atively low cortical resistance on that side. Maxillaryand mandibular wraparound retainers were used inthis patient in that period, and she had a recall check 3months later. After 26 months of retention, the patientdid not show a significant relapse tendency as she hadafter 8 months of retention (Fig 14).

    Mandibular premolar extraction without movingmolars distally would perhaps have led to a more stableresult. Despite the patients request, we should havepersuaded her to select this simpler treatment option.However, the tip-back tooth movement and long-termretention results of this patient will be helpful for clini-cians who consider similar treatment mechanics forpatients with Class III anterior crossbite.

    In cases of whole-dentition distalization, we recom-mend both a wraparound removable retainer and a fixedretainer, and that chewing be done on both sides. ClassIII intermaxillary elastics applied to a splint-typeretainer with hooks for night wear can be a good alter-native to conventional retention methods.

    CONCLUSIONS

    The C-implant can withstand heavier loads thanother skeletal anchorage systems. It also has the advan-tage that its abutment head design can be used for elasticapplications. In this case, the C-implant and multipleintra-arch elastics distalized the entire mandibularon both sides after treatment. However, she acceptedonly the fixed retainers. Eight months after debonding,significant relapse on the right side was observed. Therelapse tendency was assumed to be due to severe tip-ping of the mandibular molar distally, as can be seenin the cephalometric radiograph, and also to insufficient

    Volume 137, Number 1dentition independently, without extrusion or flaringof the maxillary dentition.of surface treatment on the osseointegration potential of orthodon-

    tic mini-implant. Korean J Orthod 2008;38:328-36.We thank Jae-Hee Cho for assisting with manuscriptpreparation.

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    Distalization of the mandibular dentition with mini-implants to correct a Class III malocclusion with a midline deviationDiagnosisTreatment objectivesTreatment alternativesTreatment progressTreatment resultsDiscussionConclusionsReferences