Conservative Management of Class I Crowded Malocclusion Complicated by Severe Maxillary Protrusion, Facial Convexity and Deepbite
Drs. Irene Yi-Hung Shih, John Jin-Jong Lin, Roberts WE.
A 20-year-9-month old male presented with a Class I malocclusion complicated with severe crowding in the lower arch (-7mm), Class II skeletal pattern (SNA 88.5º, ANB 8.8º), steep mandibular plane (FMA 29.4º), convex profile (G-Sn-Pg’ 20º), and anterior deepbite (5.5mm). Despite the severe skeletal discrepancy, the patient had good facial balance, so conservative treatment with no extractions or orthognathic surgery was indicated. The nonextraction treatment plan relied on infrazygomatic (IZC) miniscrew anchorage to retract both arches and rotate the mandible anteriorly, to decrease the vertical dimension of occlusion (VDO) and increase lower lip protrusion. Space to correct the severe crowding was accomplished with posterior arch expansion, retraction of upper and lower molars, and increased axial inclination of the lower incisors. In brief, this severe skeletal malocclusion (DI 24) was corrected in 15 months to an overall excellent outcome (CRE 16), but it was necessary to flare the lower incisors, and accept a Class II buccal occlusion on the right side, to avoid facial compromise. Step-by-step procedures are provided for the efficient camouflage approach used to resolve this severe, compensated malocclusion in an efficient manner. (Int J Orthod Implantol 2016;44:4-16)
Key words: Class I, crowding, protrusive maxilla, deepbite, non-extraction conservative treatment, TADs (temporary anchorage devices), IZC (infrazygomatic crest) miniscrews, compromise treatment, camouflage
Bimaxillary Protrusion with Missing Lower First Molar and Upper Premolar: Asymmetric Extractions, Anchorage Control
and Interproximal Reduction
Drs. Chi Huang, Chuanwei Su, Chang CH, Roberts WE.
A 38-year-old female presented with a Class I bimaxillary protrusion, complicated by asymmetric anterior spacing in both arches. Early loss of a lower right (LR) first molar resulted in mesial tipping of adjacent molars, a unilateral excessive curve of Spee, and an atrophic ridge. The upper left (UL) second premolar was missing and there was extensive subgingival calculus. Following periodontal scaling, additional extractions were needed to correct the protrusion, so the most compromised teeth in the affected quadrants were selected: upper right (UR) first premolar with cervical abrasion, a super-erupted maxillary left third molar, and a lower left (LL) first molar with extensive caries. The asymmetric extraction spaces required careful management of anchorage to retract the anterior segments without canting the occlusal plane and/or producing a midline deviation. After 34 months of active treatment, the partially edentulous compensated malocclusion with a discrepancy index (DI) of 18 was treated to an acceptable cast-radiograph evaluation score of 23. The facial profile was corrected by retraction of the lips, and the dental esthetics were improved with space closure, symmetrical alignment, and coincidence of the midlines. (Int J Orthod Implantol 2016;44:20-41)
Key words: Adult orthodontic treatment, complex asymmetric malocclusion, bimaxillary protrusion, atrophic edentulous spaces, extraction of compromised teeth, asymmetric mechanics, midline diastema
Early Treatment of Anterior Crossbite Combined with Bilateral Maxillary Labially Impacted Canines
Drs. Wei Lun Peng, Chang CH, Roberts WE.
Correction of Anomalous Tooth Form Prior to Bonding Preadjusted Orthodontic Brackets
Drs. Linda Tseng, Chang CH, Roberts WE.
Orthodontics is an art as well as a science. All preadjusted (straight-wire) appliances require precision bracket placement to efficiently achieve the desired functional and esthetic result. The geometric center of a bracket base is ideally positioned over the facial axis (FA) point, which is in the middle of the labial surface of a clinical crown, and in line with the long axis of the tooth. Prospective (pretreatment) tooth contouring may be necessary to optimally position brackets for facilitating the function and esthetics of the final alignment. A step-by-step procedure is described for reshaping anomalous tooth form to reliably bond a bracket at the desired FA point to help achieve an optimal result. (Int J Orthod Implantol 2016;44:64-71)
Extraction vs. Non-Extraction Therapy: Statistics and Retrospective Study
Drs. Chi Huang, Chang CH, Roberts WE and Ms. Laurel Shern.
Objective: Since 1970 there has been a progressive trend in Western countries toward non-extraction management for comprehensive orthodontic problems because of advances in clinical technology. It is hypothesized that extractions are rare in an Asian group practice using advanced technology, including self-ligating brackets (SLB) and extra-alveolar temporary anchorage devices (E-A TADs).
Materials and Methods: 200 consecutive patient files were drawn on October 31, 2015, from the Beethoven Orthodontic Center in Hsinchu City, Taiwan, to determine if teeth were extracted as part of a comprehensive treatment plan. Third molar extractions were not included if their removal was unrelated to the treatment of the malocclusion.
Results: The chief complaint (CC) for 47% of the patients in the sample was lip protrusion. Other concerns were prognathic (CIass III) occlusion (15%), a perceived need for interdisciplinary treatment (10%), impaction(s) (7%), and other problems (20%). In evaluating the labial profile for the patients with a CC of lip protrusion, 39% of upper and 55% of lower lips protruded beyond the Ricketts E-line. Sixty-five percent of the lip protrusion patients accepted a treatment plan involving extractions. Eighty-five percent of the extractions were performed to reduce protrusion, and maintain lip balance to the E-line. Forty percent of the patients had crowding >7mm. Twenty percent of the extractions were for compromised dental health such as caries, failed root canal treatment, fracture, and prostheses.
Conclusions: The hypothesis is rejected that advanced clinical technology has markedly decreased the extraction rate for Asians. Patients affected by lip protrusion and/or severe crowding readily accept a treatment plan to reduce the number of permanent teeth. A desirable soft tissue profile with optimal lip esthetics is a significant factor in the decision for extractions. Additionally, extractions and space closure treatment were perceived as the most efficient approach for correcting asymmetry, as well as for avoiding prostheses and/or implants. Despite the pros and cons for extraction treatment, patient expectations and treatment preference remain the most crucial factor for implementing an extraction treatment plan. (Int J Orthod Implantol 2016;44:76-86) kets, is to control rotation during alignment. Delays in reaching this goal can slow down the treatment process. (Int J Orthod Implantol 2016;43:76-79)
Key words: Extraction vs non-extraction treatment, patient treatment preference, E-line, retrospective analysis, Asian facial preference, lip protrusion, severe crowding, patient expectations