Dr. Chris H. Chang
Last week, I was invited to give a webinar, which had only been announced one month previously. Within that month, it had attracted over 3,000 doctors, a record for such an orthodontic webinar. It is amazing when one considers the logistics, effort, time, manpower, and costs it would have involved in brining so many people under one roof. What makes it even more amazing is the fact that this was all arranged using only one software, Zoom...
Conservative Treatment for Severe Skeletal Class III Openbite Malocclusion: Reversing the Etiology of Interincisal Tongue-Posture
Eric Hsu, Chris H. Chang, W. Eugene Roberts
Skeletal Class III malocclusion with bimaxillary protrusion and anterior openbite is a major esthetic and functional disability. A 15-year-old female presented for orthodontic consultation with excessive facial height (58%), concave profile (-5 ̊), facial asymmetry (chin deviated 5mm to the left), bimaxillary protrusion (SNA 85 ̊, SNB 89.5 ̊), and an intermaxillary discrepancy (ANB -4.5 ̊). The full- cusp Class III malocclusion was complicated with lower arch crowding (-5mm), anterior openbite (6mm), and posterior crossbite tendency. The Discrepancy Index (DI) was 70. A thorough diagnosis and assessment of etiology indicated an effective treatment plan: asymmetric molar extraction pattern (UR7, UL7, LR7, LL6), bone screw anchorage for retraction of the lower arch, and correction of anterior, interincisal tongue posture. This severe malocclusion was treated to a satisfactory result in 24 months without orthognathic surgery. The Cast-Radiograph Evaluation (CRE) score was 30. (J Digital Orthod 2020;60:4-16)
Key words: Skeletal Class III, full-cusp Class III, molar extraction, anterior openbite, anterior tongue posture, posterior crossbite, asymmetrical extraction, passive self-ligating appliance
Interdisciplinary Conservative Treatment for Gummy Smile and Deep Bite
Lomia Lee, Chi Huang, Chris H. Chang, W. Eugene Roberts
Diagnosis and Etiology: A 23-year-old female presented with chief complaints of excessive gingival display (“gummy smile”) and severe intermaxillary crowding (>7mm). She desired improved smile esthetics without orthognathic surgery. The constricted, underdeveloped arches suggested inadequate occlusal loading, probably associated with a relatively soft, refined diet. Increased facial height (56.5%), bimaxillary retrusion (SNA 78.5 ̊, SNB 74 ̊), and extrusion of the maxillary dentition were consistent with a transient juvenile airway problem. The Discrepancy Index (DI) was 33.
Treatment: Interdisciplinary treatment involved dentofacial orthopedic alignment followed by maxillary anterior crown-lengthening surgery. All four first premolars were extracted to correct crowding. Skeletal anchorage was provided with three bone screws: infrazygomatic crests bilaterally, and another between the apices of the upper central incisors. Differential space closure with bone screw anchorage reduced lip protrusion, intruded the maxillary incisors, and achieved a near ideal Class I alignment. Surgical crown lengthening was performed in the maxillary anterior segment.
Results: 25 months of interdisciplinary treatment achieved a near ideal dentofacial result as evidenced by a Cast-Radiograph Evaluation (CRE) score of 27, and a Pink & White dental esthetic score of 2. (J Digital Orthod 2020;60:22-35)
Key words: Gummy smile, deep bite, Class II malocclusion, bite-turbos, surgical crown lengthening, temporary anchorage devices, infrazygomatic crest, extra-alveolar, bone screws, etiology
CIass III Camouflage Treatment: Premolar Extractions, Bite Turbos, and Differential Space Closure
Bear Chen, Chris H. Chang, W. Eugene Roberts
History: A 24 year-old male presented with protruded chin, crowded dentition, and poor smile esthetics. There was no contributing medical or dental history. Previous orthodontists recommended orthognathic surgery, but the patient preferred a more conservative approach.
Diagnosis: Skeletal Class III malocclusion (SNA 89 ̊, SNB 86 ̊, ANB -3 ̊) was complicated with bimaxillary protrusion, anterior crossbite and a concave profile. Asymmetric buccal segments were more Class III on the right side (8mm), and the mandibular midline was deviated 4mm to the left. The Discrepancy Index (DI) was 42 points.
Treatment: Four 1st premolars were extracted to provide space for camouflage treatment. CIass III elastics and an inclined bite plane on the lower incisors were used to correct the anterior crossbite. The buccal segment asymmetry and crowding were resolved with differential space closure and Class III elastics in all four quadrants. Posterior crossbite tendency was controlled with cross-elastics and upper archwire expansion.
Results: Retraction of the lower anterior segment improved facial convexity from 0 ̊ to 2 ̊. After 30 months of active treatment, this severe skeletal malocclusion was corrected to an excellent Cast-Radiograph Evaluation (CRE) of 26 points and a Pink & White dental esthetic score of 5.
Conclusions: Severe Class III skeletal malocclusion can be resolved with extractions and camouflage treatment. Mandibular buccal shelf bone screw anchorage may improve incisal angulation. (J Digital Orthod 2020;60:40-55)
Key words: Class III malocclusion, non-surgical treatment, anterior crossbite, bite turbos, torque selection
Bimaxillary Protrusion and Gummy Smile Treated with Clear Aligners: Closing Premolar Extraction Spaces with Bone Screw Anchorage
Lexie Y. Lin, Chris H. Chang, W. Eugene Roberts
Inadequate posterior anchorage is a serious limitation for aligner treatment involving extraction of four first premolars. Inappropriate axial inclinations may compromise intermaxillary occlusion and stability. OrthoBoneScrew (OBS®) anchorage is designed to augment the Invisalign® clear aligner G6 solution to produce more predictable outcomes as illustrated by the current case report. An 18-year- old female presented with two chief complains: (1) protrusive, incompetent lips, and (2) excessive gingival exposure when smiling (“gummy smile”). Clinical evaluation revealed bimaxillary protrusion, hypermentalis activity, anterior crowding, and excessive anterior axial inclinations, particularly of the lower incisors (116 ̊). The American Board of Orthodontics (ABO) Discrepancy Index (DI) was 21. The treatment plan was extraction of all four first premolars, and clear aligner (Invisalign®) therapy anchored with four OBS®s: infrazygomatic crest (IZC), and between the roots of the upper central and lateral incisors (Incisal) bilaterally. Eighteen months of initial treatment with 45 aligners retracted and intruded the anterior segments in both arches by closing the extraction spaces with supplemental anchorage provided by IZC and Incisal OBS®s. The final series of 20 refinement aligners achieved an excellent outcome as evidenced by an ABO Cast-Radiograph Evaluation (CRE) score of 10, and a pink and white (P&W) dental esthetic score of 3. Post- treatment analysis revealed multiple opportunities for improvement. The patient was well satisfied with the final outcome. (Reprinted with permission from APOS Trends Orthod 2020;10(2):120-31). (J Digital Orthod 2020;60:62-79)
Key words: Bimaxillary protrusion, gummy smile, premolar extraction, clear aligner treatment, Invisalign G6, IZC, Incisal, bone screws, space closure, anchorage, torque control
Extruding Crowded and Rotated Maxillary Lateral Incisors with Clear Aligners
Alex Lin, Chris H. Chang, W. Eugene Roberts
History: A 22-yr-7-mo-old female presented with chief complaints of poor dental esthetics and infra-occlusion, defined as intruded position relative to the occlusal plane.
Diagnosis: Normal skeletal and dental relationships were associated with mild anterior crowding in both arches. Upper lateral incisors (UR2 and UL2) were in infra-occlusion, tipped labially, and rotated mesial-out. The Discrepancy Index (DI) was 22.
Treatment: The ClinCheck® software was used to design Invisalign® clear aligners (Align Technology, Inc., San Jose, CA, USA) for correction of the moderate anterior alignment problems. Attachments were bonded on all teeth as indicated. Interproximal reduction (IPR) was specified as needed. During active treatment, the maxillary arch was expanded, but the aligners went off-track on the UL2. Additional aligners were designed with improved retention to extrude the UL2 and align the entire dentition as needed.
Results: Alignment of the dentition was near ideal. The Cast-Radiograph Evaluation (CRE) score was 3, and the Pink and White dental esthetic score was 0.
Discussion: Extruding lateral incisors in the presence of crowding requires extensive IPR. Adequate space for incisor alignment is required to avoid off-tracking due to distortion and poor retention of the aligners. Auxiliaries and horizontal rectangular attachments help ensure better aligner retention and interproximal confirmation.
Conclusions: Clear aligners, with specified attachments and IPR, can efficiently align labially tipped, rotated, and intruded maxillary lateral incisors. (J Digital Orthod 2020;60:84-99)
Key words: Invisalign®, clear aligner treatment, extrusion, lateral incisor, interproximal reduction