Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-12-09, 10:06:54 | version 1.38.0
Dental Tribune Middle East & Africa Edition | 4/2016 ORTHO tribune C3 changesincludedproclinationofthe maxillary incisors and retroclination of the mandibular incisors. Torque control was essential in camouflage treatment in order to prevent fur- ther periodontal problems. Lost con- trol of anterior teeth might compro- miselong-termstability,particularly in extraction cases.6 Early usage of ARTs and the pretorqued NiTi wire on the lower arch delivered a con- tinuous light force, as opposed to a heavyinterruptedforcefromatwist- ed rectangular wire at a later stage in treatment. As the transposed right maxillary canine was moved mesial- ly, an ART spring was used to correct theaxialinclination(Fig.18). Highertorquecaninebracketswould have been more favorable for the presentcase(Fig.12). Anterior or posterior placement of biteturboscanbeusedforbiteopen- ing. For the present patient, molar extrusion and clockwise rotation of the mandible were part of the treat- ment plan, so anterior bite turbos were appropriate for this purpose. Withbiteturbosandearlylightshort elastics (Class III vector), the anterior crossbite was corrected within seven months.ShortClassIIIelasticsonthe rightsidealsoprovidedanextrusion force for the infra-occlusion right mandibular canine and redirected the displaced mandible to return to its normal position. This approach would not be appropriate for pa- tients with a true severe skeletal asymmetry and large discrepancy in ramus height. Carefully monitoring of the treatment response is criti- cal for success. For instance, incisal occlusal stress due to anterior bite turbos may contribute to the root resorption of the maxillary incisors in some patients. A progress radio- graph six months into treatment would have been appropriate be- cause the root of the left maxillary central incisor appears to be mod- erately resorbed prior to treatment (Fig. 7). Fortunately, the panoramic radiograph at the end of treatment showed no significant progression of maxillary incisal root resorption (Fig.8) Temporary anchorage devices (TADs), placed lateral to the alveo- lar processes (mandibular buccal shelves, infrazygomatic crests) are a break-throughfortreatmentofClass III malocclusions.5,7 The stationary anchorage of TADs facilitate retrac- tionoftheentirelowerarch,without proclination (anterior tipping) of maxillary incisors7 or deterioration of smile arc, two common problems with Class III elastics (Fig. 19).5,8 For many Asians, the major contribu- tory factor for Class III malocclusion is mandibular prognathism with normal mid-face development.9 TADs provide reliable anchorage for Class III treatment without creating the undesirable effects seen with in- termaxillary elastics. For the present patient, the application of TADs was considered, but discarded because of theacceptableupperlipprominence (Fig. 20), and the transposition of the maxillary right canine and first pre- molar. Nonextraction treatment of the transposition with TAD anchor- age would have been very difficult. Since extraction of the maxillary left first premolar was necessary, the most expedient approach was to remove all four first premolars, and treat the patient with conventional mechanics. As mentioned previously, smile arc preservation is crucial for an esthetic result with Class III cases.10 Acker- man reported that 40% of routine orthodontics corrections show a deterioration in smile arc.11 The na- ture of Class III mechanics include molar extrusion, counter clockwise rotation of the occlusal plane8 (Fig. 17), and torque change in incisors of both arches. These side effects fur- therchallengesmilearcpreservation during Class III (Fig. 19) treatment. Restrictive usage of Class III elastics, in combination with Class II elastics and TADs in the mandible, can effec- tively enhance the smile arc.7 How- ever, the biomechanical boundary remains definitive, regardless of the treatment methods.12 As proposed byKondo,13,14 theanteriorlimitforin- cisor retraction is the posterior bor- der of the symphysis, while the PM or ramus line is the posterior limit forarchretraction(Fig.21). Asymmetricalcorrectioniscomplex, and often involves various mechan- ics, including intra-arch auxiliaries15 and multiple loops, for realigning and coordinating the arch.16 These special mechanics are often associ- ated with undesirable side effects like compromised molar angulation to meet occlusal goals at the end of treatment.17 Low fiction, selfligating brackets with special elastics con- figurations simplify this challenge significantly. Although the 4mm midline deviation, that was evident after correction of the functional shift, was not completely corrected for the present patient, but the re- sult was satisfactory. The CRE score was 22, with most of the points de- ducted for inadequate third order correction of the maxillary posterior segments, which is reflected in the scores for buccolingual inclination (4 points) and lingual cusp contacts (3points).Morebuccalroottorquein the maxillary buccal segments and additional detailing with wire bend- inginthefinishingstagewouldhave improvedthefinalresult.18 Conclusion Skeletal Class III treatment with camouflage orthodontics presents significant clinical challenges. The treatment is further complicated with Asian patients who present with hereditary etiology and severe crowding. Orthopedic treatment with rapid maxillary expansion, a facemask or a chincap show varying degrees of success, due to different protocols and case selection.19,20 With the help of self-ligating brackets, bite turbos,andaproperlydesignedforce system, clinicians can now deliver relatively efficient extraction treat- ment that achieves a satisfactory re- sult. However, the progress of treat- ment should be carefully monitored tocontrolpotentialcomplications. Acknowledgment Thanks to Ms. Tzu Han Huang for proofreadingthisarticle. References 1. Proffit WR, White RP Jr. Who needs surgical-orthodontic treatment? Int J Adult Orthodon Orthognath Surg. 1990;5(2):81-9. 2. Gazit-Rappaport T, Weinreb M, Gazit E. Quantitative evaluation of lip symmetry in functional asym- metry. Eur J Orthod. 2003;25(5):443- 50. 3. Baccetti T, Franchi L, McNamara JA Jr. Thecervial verteral maturation (CVM) method for assessment of optimal treatment timing in dentof- acial orthopedics. Sem Orthod. 2005;11:119-129. Fig.18.Earlytorquecontrolinrightmaxillarycaninecontributedgoodtorqueexpressin themiddleof treatment (Arrow:root torquespring) Fig. 19. Flattening of smile arc after Class III correction is a common side effect in tradi- tionalinterarchClassIIImechanics. Fig.20.AnacceptableupperlipprofilewithoutTADsanchorage. Fig. 21. Anterior and posterior bound- ary of the whole arch distalization in the mandible. 4. Tseng YC. Treatment of adult Class III malocclusions with orthodontic therapy or orthognathic surgery: re- ceiveroperatingcharacteristicanaly- sis. Am J Orthod Dentofacial Orthop. 2011;139(5):485-93. 5. Lin JJ. Treatment of Severe Class III with Buccal Shelf Mini-Screws. News & Trends in Orthodontics 2010;18:4- 13 6. Zachrisson BU. Important aspects of long-term stability. J Clin Orthod. 1997;31(9):562-83. The complete list of references avail- ablefromthepublisher ReprintedwithpermissionfromInter- national Journal of Orthodontics and Implantology. â—ŠPageC2