Dr. Chris H. Chang
Prediction is Difficult
Last month, we were fortunate enough to have been invited to participate in the first Graphy Shape Memory Aligner Summit Symposium, which was held in Seoul, South Korea. Five of our most active and dynamic young orthodontists had been appointed to participate in the event focusing on the materials and technologies of the next generation in aligners, thanks to the arrangements of my good friend, Dr. Kenji Ojima.
I started to learn orthodontics 35 years ago. At that time, there was an emerging trend which used a new material called shape-memory alloy, a material which remembers its original shape. It was used in NASA’s space shuttles since shuttles made from this material could change their shape when entering into the absence of gravity of outer space, and then return to the original shape upon re-entering Earth’s atmosphere. This idea inspired orthodontists to consider that this material would be most suitable for applications used in orthodontic correction, as placing crooked wires on the dentition which would return to perfectly curved lines would effectively bring the teeth into an ideal position…
Skeletal Class III Malocclusion with a High Mandibular Plane Angle Treated with Four First Premolar Extractions
Hsuan Cheng Chu, Chun-Hung Chen, Chris H. Chang, W. Eugene Roberts
History: An 18yr-8mo-old female presented with chief complaints of a prognathic mandible and a protrusive lower lip.
Diagnosis: Cephalometric analysis revealed a skeletal Class III relationship (SNA, 75.5˚; SNB 77.5˚; ANB, -2˚), as well as reduced facial convexity (-1˚) and a high mandibular plane angle (SN-MP, 39˚). A functional shift was noted. The upper and lower midlines were both deviated 2 mm to the right of the facial midline, and the chin was also shifted to the right. An intraoral assessment revealed a bilateral full-cusp Class III malocclusion with anterior crossbite. Mild crowding was evident in the upper and lower arches. The Discrepancy Index (DI) was 30.
Treatment: A Damon® system appliance with passive self-ligating brackets was applied to correct the malocclusion after extraction of four first premolars. Anterior bite turbos and early light short Class III elastics were used to correct the anterior crossbite. Space closing was also accomplished with elastics. The active treatment was 29 months with no temporary skeletal anchorage devices used.
Results: Improved dentofacial esthetics and occlusal function were achieved after the treatment. The overjet was corrected, and the lower lip was retruded. The Cast-Radiograph Evaluation (CRE) score was 16, and the Pink and White esthetic score was 2. The posttreatment panoramic radiograph shows complete space closure and good root parallelism.
Conclusions: This case report demonstrates that the use of passive self-ligating brackets helps resolve skeletal and dental Class III malocclusion. Neither orthognathic surgery nor temporary skeletal anchorage devices were necessary. (J Digital Orthod 2023;70:4-21)
Key words: Skeletal Class III, full-cusp Class III, anterior crossbite, midline deviation, passive self-ligating brackets, temporary skeletal anchorage devices (TSADs)
Severe Class III Malocclusion with Deep Overbite and Blocked-Out Canines: Conservative Correction with Premolar Extractions
Linda Tsai, Joshua S. Lin, Chris H. Chang, W. Eugene Roberts
History: A 20-year-old female presented with chief complaints of a prominent chin and crowded teeth.
Diagnosis: Clinical examination revealed mandibular prognathism, blocked-out canines, skeletal Class III (ANB = -3˚), anterior crossbite, and deep overbite. The Discrepancy Index (DI) was 37.
Treatment: Bilateral upper and lower first premolars were removed to gain space for relieving the crowding and retracting the lower anterior segment to correct the anterior crossbite. A passive self-ligating (PSL) bracket system was bonded on the dentition with high-torque brackets on the lower incisors and low-torque brackets on the upper incisors.
Outcome: After 24 months of active treatment, this challenging full-cusp Class III malocclusion was corrected to a near ideal result. The Cast-Radiograph Evaluation (CRE) score was 19, with an excellent Pink and White dental esthetic score of 2. (J Digital Orthod 2023;70:28-42)
Key words: Skeletal Class III, full-cusp Class III molar relationship, first premolar extraction, passive self-ligating brackets
Efficient Procedure for Precise Bonding of Aligner Attachments
Joshua S. Lin, Chris H. Chang, W. Eugene Roberts
Computer-generated attachments, as specified in the ClinCheck® simulation, must be precisely duplicated chair-side on the patient’s dentition. This article describes the use of flexible attachment templates for each quadrant. Windows (reliefs) for each specified attachment are filled with composite resin that is bonded on the surface of the teeth. Standard operative procedure, quality control checks, and patient training are reviewed. This article provides step-by-step descriptions and illustrations for efficiently and precisely initiating aligner therapy. This protocol is standard operating procedure at the Beethoven Orthodontic Center. (J Digital Orthod 2023;70:52-61. Reprinted from J Digital Orthod 2020;59:64-73)
Taiwanese Lifestyle Through the Eyes of CC
Chapter 9. Maximizing spaces and resources - Regenerating dead space and your soul
“Creativity is seeing what others see and thinking no one else ever thought.” - Albert Einstein
In housing design, there is always an inevitable sacrifice of space in order to achieve certain functions or purposes. If such spaces are big enough, they may be turned into something else; for example, the triangular space under staircases is often fitted with shelves and cupboards to serve as storage, or in older Taiwanese residences, a bathroom. However, what if the space is just too fragmentary and difficult for common uses? One such example would be the gap under an access ramp, which is more often than not filled up with solid concrete.
The need for wheelchair access for Dr. Chang’s mother promoted the addition of a ramp to connect their two houses, and since the neighborhood is situated on a slope, a discrepancy in ground levels exists. As the ramp goes past Dr. Chang’s spectacular front yard aviary, the logic of space extension has again been implemented in the ramp’s design, similar to how the garage ceiling was converted into an aviary extension (see chapter 8)…