Chris H. Chang
The New Way of Learning
Recently, I was invited to give a two-day lecture in Turkey, after which the organizer arranged a visit to Cappadocia, an ancient city in Turkey renowned for its unique hills and recognized as a UNESCO World Heritage Site. We spent three days there enjoying the incredibly beautiful scenery. Apart from visiting the city's main attractions, we also flew in a hot air balloon ride soaring above the landscape, making it a very enriching journey. When the journey had ended, I reflected on the entire trip to Turkey and asked myself: Was it worth it to experience such a fantastic place? The answer is obviously a resounding yes. However, another question also arose: Is it worth the effort to travel all the way to distant Turkish destinations? The answer is a clear NO. If you happen to be there, visiting Cappadocia is a must, but it is not worth going out of your way to visit such a remote place. To appreciate the beauty of Cappadocia, there are many videos on YouTube that offer even more spectacular and beautiful views than your firsthand experience. It genuinely does not require so much time and effort to go there….
Full-Cusp Class II Malocclusion with 12 mm Overjet:
Non-Extraction Treatment with Bone Screws and Passive Self-Ligating Appliance
Debby Y.W. Sung, Lily Y. Chen, Chris H. Chang, W. Eugene Roberts
History: A 12-year-old female presented with flared maxillary central incisors.
Diagnosis: The skeletal Class I relationship (SNA, 85˚; SNB, 80˚; ANB, 5˚) was associated with a full-cusp Class II molar relationship on the right side and an end-on Class II molar relationship on the left side. Dental analysis revealed flared maxillary central incisors (U1-to-NA, 10 mm; U1-to-SN, 128.5˚) with an excessive overjet of 12 mm. The facial profile was convex with protrusive lips (1.5 mm/4.5 mm to the E-line). The Discrepancy Index was 20.
Treatment: A fully fixed passive self-ligating (PSL) appliance was bonded on all present permanent teeth (UR6-UL6 and LL6-LR6). Skeletal anchorage was provided by bilateral infrazygomatic crest (IZC) miniscrews. Class II elastics were implemented to reduce the overjet and overbite.
Results: After 22 months of active treatment, satisfactory facial profile and dental alignment were achieved. The Cast-Radiograph Evaluation score was 18, and the Pink and White esthetic score was 0.
Conclusions: A full-cusp Class II malocclusion with 12 mm overjet, flared U1s, 100% overbite, and periodontal impingement was treated without extraction. Bilateral IZC anchorage facilitated the retraction of the entire maxillary dentition. The 12 mm overjet was corrected to a pleasing result with stability noted at the 5-year follow-up. (J Digital Orthod 2023;72:4-18)
Key words: Excessive overjet, full-cusp Class II malocclusion, periodontal impingement, Class II elastics, infrazygomatic crest miniscrews, passive self-ligating appliance, interproximal reduction
Labially Impacted Maxillary Canine with Class III Malocclusion: Bone-Anchored 3D Lever Arm Mechanics
Jenny Chang, Kristine Chang, Chris H. Chang, W. Eugene Roberts
Introduction: A 17-year-old female was referred by another dentist to assess her impacted canine.
Diagnosis: The patient was skeletal Class I (SNA, 84.5˚; SNB, 81˚; ANB, 3.5˚) with bilateral end-on Class III molar relationships. Her profile suggested a Class III malocclusion since she had a high mandibular angle of 48˚. The upper left deciduous canine (ULc) was present, the UL3 was labially and horizontally impacted, and root resorption of the apex of the UL2 was noticed. The Discrepancy Index (DI) was 47.
Treatment: The impacted canine was treated using the vertical incision subperiosteal tunnel access (VISTA) technique and a custom 3D lever arm anchored by an OrthoBoneScrew® (OBS) inserted in the left infrazygomatic crest (IZC) to produce a submucosal space for retracting and extruding the impaction and aligning it into the normal canine position.
Outcome: After 30 months of active treatment, the impacted upper left canine was recovered and aligned in an ideal relationship. The Cast-Radiograph Evaluation (CRE) was 16, and the dental esthetic (Pink & White) score was 4.
Conclusions: The VISTA surgical exposure is a unique approach for submucosal movement of the impactions. Skeletal anchorage using OBS with a 3D lever arm provides an independent force system for retracting the impaction. (J Digital Orthod 2023;72:26-49)
Key words: Impacted maxillary canine, infrazygomatic crest miniscrews, bone screw anchorage, vertical incision subperiosteal tunnal access (VISTA), 3D lever arm, root resorption
Class II Excessive Overjet and Deep Bite with a Congenitally Missing Lower Incisor
Yi-Hsuan Lin, Joshua S. Lin, Chris H. Chang, W. Eugene Roberts
Introduction: An 11-year-old female presented with chief complaints of flared upper central incisors and protrusive lips.
Diagnosis: The cephalometric analysis revealed a skeletal Class II relationship (SNA, 84˚; SNB, 76˚; ANB, 8˚) and proclined upper incisors. An intraoral assessment revealed a congenitally missing lower right lateral incisor, large overjet, deep overbite, and lower midline deviation 3 mm to the right. There was 4-5 mm of crowding in the lower anterior dentition. The Discrepancy Index (DI) was 23.
Treatment: A Damon® system appliance with passive self-ligating brackets was applied to correct the dental malocclusion after extracting both upper first premolars. Asymmetrical extraction of the lower left central incisor was carried out due to the congenitally missing lower right lateral incisor. Space closure and midline correction were accomplished with elastomer chains and Class II elastics. The active treatment time was 28 months.
Results: Improved dentofacial esthetics and occlusal function were achieved after treatment. The Cast-Radiograph Evaluation (CRE) was 27, and the Pink and White esthetic score was 3. Neither significant root resorption nor periodontal problems were noted.
Conclusions: This case report demonstrates the use of passive self-ligating appliances to resolve a severe anterior overjet with deep bite without using an orthodontic bone screw. (J Digital Orthod 2023;72:56-70)
Key words: Skeletal Class II, excessive overjet, deep bite, congenitally missing lower incisor, proclined anterior teeth, midline deviation