Editorial: Less is More

Dr. Chris H. Chang

The question that has been at the back of my mind since the last issue has been how to ensure that a patient can be confident of a graduated student’s skill proficiency after 3 years of training. I think that this question is relevant not only to our profession, but really to any skills that one pursues. Those of you who know me better can all now figure that playing the violin and golf are those which come into my mind…

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Non-Extraction Treatment of a Class II Openbite with Amelogenesis Imperfecta

Drs. Yu-Hsin Huang, Kim-Choy Low, Po-Jan Kuo, John Jin-Jong Lin, W. Eugene Roberts

Abstract

Introduction: A 15-year-7-month-old female with a history of amelogenesis imperfecta (AI) presented with chief complaints of poor dental esthetics and anterior openbite.

History and Etiology: AI is a hereditary disorder that is usually manifested as an autosomal dominate trait involving defective ENAM gene(s). For the present patient, deficient enamel resulted in decreased biologic width of the epithelial attachment, in addition to dental attrition that reduced the heights of clinical crowns. Selective crown lengthening and complete provisional restoration were required. Habitual interdental tongue posture, which may reflect a history of airway compromise, resulted in an anterior openbite that induced posterior mandibular rotation to produce a long face.

Diagnosis: AI-related enamel deficiency has compromised the periodontium and dentition. Facial form was convex (12°) with increased lower facial height (59.5%), and a steep mandibular plane angle (FMA 37.5°). Cephalometrics revealed a protrusive maxilla (SNA 84.5°), retrusive mandible (77.5°), and an intermaxillary discrepancy of ANB 7°. The bilateral Class II malocclusion was complicated with anterior openbite, canted occlusal plane, and mandibular deviation to the left. The Discrepancy Index (DI) was 62.

Treatment: Crown lengthening surgery and revised provisional restorations established a healthy periodontium in preparation for orthodontic treatment. A fixed passive self-ligating appliance, with high torque brackets in the upper anterior segment, was bonded on both arches. Anchorage to intrude upper molars was provided with bilateral infra-zygomatic crest (IZC) bone screws. After initial orthodontic alignment, interproximal space was increased as needed with elastic separators to prepare gingival margins, and a new set of optimized provisional restorations was fabricated. Orthodontic finishing was accomplished with the same fixed appliance.

Results: Crown lengthening produced healthy periodontium with proper biological width in preparation for full provisional restoration and orthodontic alignment. As upper molars were intruded, the mandible rotated anteriorly, and the lower facial height decreased as lip and chin protrusion increased. This challenging openbite malocclusion, with a Discrepancy Index (DI) of 62, was treated in 22 months to an excellent outcome: Cast-Radiography Evaluation (CRE) score of 11, and Pink & White dental esthetic score of 1. An upper removable retainer was provided for night-time wear.

Conclusions: A patient with AI and an anterior openbite malocclusion was treated to a stable occlusion with a passive self-ligating fixed appliance and IZC bone screw anchorage. Interdisciplinary treatment with periodontics and prosthodontics was required before and after orthodontic therapy to appropriately restore dentofacial esthetics and function. (J Digital Orthod 2020;57:4-23)

Key words: Class II, openbite, occlusal cant, bimaxillary protrusion, molar intrusion, infrazygomatic crest screw, amelogenesis imperfecta, therapeutic provisional restoration
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Retreatment of Skeletal Class III Malocclusion: Insignia^TM CAD-CAM Custom Appliance for Orthodontics and Orthognathic Surgery

Drs. Hsin-Yin Yeh, Edward Chen, Kuan-Chou Lin, Chris H. Chang, W. Eugene Roberts

Abstract

History: Despite orthodontic treatment at age 12yr, a 17yr female presented with a severe skeletal Class III malocclusion.

Etiology: Inadequate dental loading contributed to constricted arches, and airway insufficiency resulted in low tongue posture with mandibular protrusion.

Diagnosis: In centric occlusion (Co), the facial profile was concave (-12 ̊), lips were retrusive to the E-line (-9mm/-3mm), and occlusal relationships were bilateral Class III with anterior and posterior crossbite. Skeletally, the maxilla was retrusive (SNA 78 ̊), mandible was protrusive (SNB 86 ̊), and the lower midline was deviated 4mm to the left. Crowding was severe in both arches (-13mm/-22mm), resulting in block-out of upper canines (U3s) and lower second premolars (L5s). The ABO Discrepancy index (DI) was 49.

Treatment: A custom, stainless steel fixed appliance (Insignia^TM System, Ormco, Brea, CA) was constructed to achieve ideal alignment with full-sized rectangular archwires. Digital set-up via computer-assisted design (CAD) specified custom brackets, produced with computer-assisted manufacturing (CAM). Treatment sequence was: 1) extraction of U4s and L5s, 2) progressive straight-wire alignment, 3) space closure, 4) two-jaw orthognathic surgery, 5) reduction genioplasty, and 6) finishing.

Outcomes: Seventeen months of treatment resulted in an excellent ABO Cast-Radiograph Evaluation (CRE) score of 17 with near ideal dental esthetics (Pink & White Score 1).

Conclusions: Surgical correction of severe skeletal Class III malocclusion was very efficient because precise presurgical alignment facilitated surgical correction of the intermaxillary skeletal discrepancy. (J Digital Orthod 2020;57:28-45)

Key words: Insignia^TM system, passive self-ligating bracket, archwire sequence, custom bracket, high Le Fort I osteotomy, oblique ramus osteotomy, genioplasty
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Canine Substitution Treatment of Class III Malocclusion, Crossbite with a Congenitally Missing Upper Incisor and a Peg Lateral Incisor

Drs. Claire JY Chen, Angle Lee, Chris H. Chang, W. Eugene Roberts

Abstract

History: Upper right lateral incisor (UR2) is congenitally missing, and upper left lateral incisor (UL2) is peg-shaped.

Diagnosis: A 30-year-old male presented with increased facial height (58.5%), and a markedly increased mandibular plane (SN-MP 49°), but a normal facial profile (13°). Intraoral examination revealed an asymmetric Class III malocclusion, lingual crossbite of the upper right first molar (UR6), anterior crossbite from canine to canine (UR3-UL3), missing UR2, peg-shaped UL2, and upper midline deviation 4mm to the left. The ABO Discrepancy Index (DI) was 50 points.

Treatment: The peg-shaped UL2, and both lower first premolars (LR4, LL4) were extracted. A full fixed passive self-ligation (PSL) Damon Q^® appliance was bonded on all permanent teeth. Four bite turbos were bonded on lower arch: LR6, LR3, LR1, and LL6. The anterior crossbite was corrected with Class III elastics, and the maxillary anterior spaces were closed in the upper arch to achieve bilateral canine substitution. Torque control of the U3s was accomplished with specific bracket selection and torquing auxiliary springs. Increasing the lower facial height to correct the anterior crossbite increased the facial convexity, but the patient maintained lip competence.

Outcome: This very difficult malocclusion (DI 50) was treated in 34 months to an acceptable result: ABO Cast-Radiograph Evaluation (CRE) 29 points, and Pink & White Esthetic Score 4. (J Digital Orthod 2020;57:52-67)

Key words: Canine substitution, missing lateral incisor, crossbite, bite turbos, early light short elastics (ELSE), torquing auxiliary spring, peg lateral incisor
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A Minimally Invasive Approach for Anterior Crossbite Correction without Surgery and Screws

Drs. Linda Tseng, Chris H. Chang, W. Eugene Roberts

Abstract

History: A 17yr male presented with a chief compliant of anterior crossbite. The probable etiology of the malocclusion was ectopic eruption of the maxillary central incisors at ~6yr of age. There was no other contributing medical or dental history.

Diagnosis: In centric occlusion (C_O), the buccal segments were Class I but all the maxillary incisors were in crossbite. In centric relation (C_R), the incisors were end-to-end consistent with ~1.5mm C_R → C_O discrepancy. Cephalometrics in (C_O) revealed bimaxillary protrusion (SNA 86.5°, SNB 86°, ANB 0.5°), relatively flat FMA (17°), and an everted lower lip. The ABO Discrepancy Index (DI) was 24.

Treatment: A passive self-ligating appliance was installed, along with bite turbos on the lower incisors and second molars. Class III elastics, bite turbos, and torque-specific brackets were used to correct the anterior crossbite. Molars were extruded to open the bite and increase facial convexity. Progressive archwire therapy aligned and detailed the dentition. After 19 months of treatment, near ideal dentofacial esthetics and function were achieved.

Outcome: The Cast-Radiograph-Evaluation (CRE) score was 27, and the Pink & White esthetic score was 4. (J Digital Orthod 2020;57:76-92)

Key words: Anterior crossbite, deep bite, minimally invasive approach
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