Dr. Chris H. Chang
“It has been documented.” - Dr. Charles Burstone, 2011
I am frequently asked where my enthusiasm for publishing orthodontic case reports comes from. Whilst contemplating this question, I have pondered deeply to try and determine the potential source of this drive and the significance of its importance. As is often the case, it is necessary to turn back the clock, by approximately 36 years, to the time when I began to learn orthodontics.
My main source of information during that pre-Google/internet era was the prestigious journal American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO). I sought relevant reports from AJO-DO to ascertain the answers to my questions. This was for me the most effective way, and those articles became my most loyal and trustworthy friends…
Skeletal Class III Malocclusion with Anterior and Posterior Crossbites: Camouflage Treatment with Mandibular Second Molar Extractions and TSADs
Hsuan-Cheng Chu, Chris H. Chang, W. Eugene Roberts
History: An 18-year-8-month-old male was referred for orthodontic consultation with chief complaints of a prognathic mandible, anterior spaces, and open bite.
Diagnosis: Cephalometric analysis showed a skeletal Class III relationship with bimaxillary protrusion (SNA, 90˚; SNB, 92.5˚; ANB, -2.5˚). Clinical examination revealed a severe anterior crossbite (overjet = -5mm), an anterior open bite, bilateral lingual posterior crossbite, and full-cusp Class III molar relationship. There were small spaces between the anterior teeth in both arches. The mandibular dental midline deviated 1mm to the right. The chin shifted 3mm to the right. The Discrepancy Index for this severe skeletal malocclusion was 71.
Treatment: Bone screws were placed in the mandibular buccal shelves to retract the mandibular arch. Bilateral lower second molars were extracted to create posterior spaces for retracting the mandibular arch to correct the anterior crossbite. A Damon® system full-fixed appliance with passive self-ligating brackets was applied to correct the dental malocclusion. Early light Class III elastics were also used to facilitate the anterior crossbite correction. The posterior crossbite was a big challenge, which was resolved with cross elastics and careful archwire adjustment. The active treatment was 26 months. A surgical crown-lengthening procedure was performed to increase the esthetic outcome of the maxillary anterior teeth.
Results: After 26 months of active treatment, this severe skeletal Class III malocclusion was conservatively corrected to an excellent result without orthognathic surgery. The Cast Radiograph Evaluation was 31 points, and the Pink and White dental esthetic score was 1.
Conclusions: This case report demonstrates that the use of passive self-ligating appliances, lower second molar extractions, and buccal shelf screws can resolve a severe anterior negative overjet combined with an anterior open bite and lingual posterior crossbite without orthognathic surgery. (J Digital Orthod 2022;67:4-22)
Key words: Skeletal Class III, anterior crossbite, anterior negative overjet, anterior open bite, posterior crossbite, temporary skeletal anchorage devices (TSADs)
Non-Extraction Treatment of Class III Malocclusion with Clear Aligners and Buccal Shelf Screws
Lily Y. Chen, Bear C. Chen, Chris H. Chang, W. Eugene Roberts
History: An 18yr-9m-old male presented with a Class III malocclusion with negative overjet. His chief complaints were crowding and a protrusive lower lip. He previously rejected treatment with extractions or orthognathic surgery.
Diagnosis: The cephalometric analysis revealed skeletal Class III (SNA, 82˚; SNB, 85˚; ANB, -3˚), high mandibular angle, flared upper incisors, and retroclined lower incisors. An intraoral examination documented negative overjet, anterior crowding on both arches, and posterior buccal crossbite on U7s. The Discrepancy Index was 32 points.
Treatment: A camouflage, non-surgical approach without extractions was indicated. Buccal shelf (BS) bone screws (2x12-mm, OrthoBoneScrew®, iNewton, Inc., Hsinchu City, Taiwan) were used as anchorage to retract the mandibular dentition, and Class III elastics corrected the intermaxillary discrepancy. Inter-proximal reduction and arch expansion were prescribed in order to provide spaces for arch alignment.
Results: The facial profile was improved with a more balanced lip position. Torque control for the upper and lower incisors was excellent. After 28 months of active treatment, the skeletal Class III malocclusion was corrected to an excellent Cast-Radiograph Evaluation score of 24 points and a Pink & White dental esthetic score of 4.
Conclusions: When correcting skeletal Class III with camouflage treatment, spaces are usually provided through extraction, inter-proximal reduction, and/or arch expansion. However, buccal shelf bone screw anchorage combined with Class III elastics is a powerful weapon to retract the mandibular arch. (J Digital Orthod 2022;67:28-43)
Key words: Class III malocclusion, camouflage treatment, non-surgical treatment, buccal shelf screw, Class III elastics, clear aligner
Lower First Molar Extraction to Treat a Class III Malocclusion with Three-Dimensional Problems
Daisy T. Lin, Lexie Y. Lin, Chris H. Chang, W. Eugene Roberts
Introduction: A 24-year-old female presented with chief complaints of protruded chin, protrusive lower lip, and poor smile esthetics.
Diagnosis: Cephalometric analysis showed a skeletal Class III relationship (SNA, 81˚; SNB, 84˚; ANB, -3˚) with high mandibular plane angle (SN-MP, 50˚). An intraoral assessment revealed bilateral Class III malocclusion with anterior crossbite (UR1, UR2, UR3, UL1, UL2, and UL3), and the lower midline was deviated 1.5mm to the right. Mild crowding was present in the lower anterior dentition. The Discrepancy Index (DI) was 61.
Treatment: A Damon® system appliance with passive self-ligating brackets was applied to correct the dental malocclusion after extracting four molars (UR8, UL8, LR6, and LL6). Posterior bite turbos and early light short Class III elastics were used to correct the anterior crossbite. Space closing and midline correction were also accomplished with elastics. The active treatment time was 29 months. The dentition was aligned, and space was created for an implant-supported prosthesis (ISP) to restore UL6.
Results: Retraction of the lower anterior segment and adjacent lip was achieved to improve the profile. After 29 months of active treatment, this severe skeletal malocclusion was corrected to an excellent Cast-Radiograph Evaluation (CRE) of 23 points and a Pink and White esthetic score of 9. No root resorption nor periodontal problems were noted.
Conclusions: This case report demonstrates the use of passive self-ligating appliances to resolve skeletal and dental Class III malocclusions without orthognathic surgery. (J Digital Orthod 2022;67:50-66)
Key words: Skeletal Class III, full-cusp Class III, non-surgical treatment, anterior crossbite, torque selection, bite turbos
Taiwanese Lifestyle Through the Eyes of CC
Maximizing Spaces and Resources - Natural Habitat Aviary
The true secret of happiness lies in taking a genuine interest in all details of daily life.” - William Morris
Dr. Chang’s orthodontic journey began 36 years ago. Along the way, there has been excitement, a sense of fulfillment, and contentment; however, not until the last couple of years has he learned to slow down and step a little off track to appreciate ordinary happiness that occurs while he goes about his daily life.
Bird-keeping has recently become Dr Chang’s new-found passion. Throughout this lifestyle series, his effort and determination to create a close-to-nature shelter for his feathered companions is apparent and unquestionable. Even so, sometimes it still takes painful experience to develop a fully protected home for the birds so that neither natural hazards nor careless human actions endanger them…