JDO Vol. 77
Editorial
Chris H. Chang
American Orthodontic Innovation Award - John Valentine Mershon Memorial Award
It is an incredible honor to stand before you today as the recipient of the John Valentine Mershon Memorial Award. This award holds a profound significance - not only because of its prestigious legacy within the American Association of Orthodontists, but also because of what it represents: a commitment to innovation, education, and the advancement of our profession.
I am deeply humbled to be included among the distinguished individuals who have received this award before me. It is both a recognition of past efforts and a powerful encouragement to continue striving for excellence in orthodontic care and research…
Conservative Treatment of an Angle Class III Malocclusion with Severe Open Bite and Negative Overjet with Clear Aligners
Nawal J. Almutawa, Vicky T. Huang, Chris H. Chang, W. Eugene Roberts
History: A 31-year-old male presented for orthodontic consultation with a severe Class III malocclusion, anterior open bite of 5 mm, and a posterior crossbite on both sides.The chief complaints were poor esthetics and inadequate masticatory function.
Diagnosis: A narrow upper arch and constricted in the 1st molars area, resulted in a crossbite relation on both sides. There was a wide lower arch and moderate crowding in the lower anterior dentition. Anterior open bite was 5 mm, extending to the 2nd premolar area. There was a full-cusp Class lII malocclusion with end-to-end crossbite on both sides. However, cephalometric analysis showed a Skeletal Class I relationship with a straight profile. The etiology for the the anterior open bite is likely related to external factors such as pre-existing thumb-sucking as a child and existing habits such as mouth breathing and interincisal tongue posture which inhibited eruption of upper and lower anterior teeth. There was proclination of upper incisors and crowding of lower incisors. A high mandibular angle (FMA, 35 ̊) led to a hyperdivergent facial pattern, anterior open bite, and Class III malocclusion.
Treatment: A non-surgical, orthodontic approach with clear aligners and elastics was planned. Full pre-treatment evaluation was carried out. Digital intraoral scanning for digital impressions were done by iTero Element II. Full records and prescription form were submitted for Invisalign comprehensive clear aligners. On arrival of the aligners, a set of 59 aligners was prescribed. After one week, at the second visit, attachments where bonded, and early Class III elastics were used. The patient was appointed every 4 weeks, with 7-day intervals between aligner changes. On completion of the aligner treatment, a significant improvement in overjet and overbite, as well as Class I molar and canine relationships on both sides, were achieved. Retention was done with clear retainers. (J Digital Orthod 2025;77:4-20)
Outcomes: Treatment goals were achieved after 18 months of treatment with clear overlay aligners.
Key words: Class llI malocclusion, Class llI molar relationship, open bite, crossbite, Class Ill elastics, overjet , overbite
Download Article
Severe Class III Malocclusion with Anterior Crossbite and Anterior Crowding: Camouflage Treatment with Premolar Extractions
Jason J. Wu, Jenny Y. Chang, Chris H. Chang, W. Eugene Roberts
History: A 33-year-old male presented with chin protrusion and crossbite.
Diagnosis: A skeletal Class III relationship (SNA, 81˚; SNB, 85.5˚; ANB, -4.5˚) along with a full-cusp Class III molar and canine relationships were noted. Dental analysis revealed retroclined upper central incisors (U1-to-NA, 9 mm; U1-to-SN, 103.5˚) and retroclined lower incisors (L1-to-NB, 7 mm; L1-to-MP, 83.5˚) with an overjet of -4 mm and an overbite of 5 mm. The facial profile was concave. The Discrepancy Index (DI) was 39.
Treatment: Extractions of both maxillary second premolars and mandibular first premolars were performed to create enough space for relieving the anterior crowding and retracting the mandibular arch. A passive self-ligating fixed appliance was utilized with Class III elastics, bite turbos, and open coil springs.
Results: After 39 months of treatment without orthognathic surgery, a near-ideal profile and satisfactory occlusal alignment were achieved. The Cast-Radiograph Evaluation score was 10, and the Pink and White esthetic score was 7. There were two main discrepancies: the upper right first premolar, lower left second premolar, and lower right first molar were rotated. In addition, the mesiobuccal cusp of the lower left second molar was 1 mm out of contact, and the distobuccal cusp was 2 mm out of contact.
Conclusions: This case report demonstrates that premolar extraction is crucial in treating a severe Class III malocclusion with anterior crowding. Torque selection is vital for controlling the axial inclination of incisors. Using specific brackets and Class III elastics potential torque loss was compensated. Class III elastics combined with posterior and anterior bite turbos, as well as open coil springs, effectively corrected the anterior crossbite and facilitated overjet correction while minimizing patient discomfort. (J Digital Orthod 2024;77:24-39)
Key words: Skeletal Class III, full-cusp Class III, anterior crowding, anterior crossbite, premolar extraction, passive self-ligating appliance, camouflage treatment
Download Article
Center of Resistance: Critical Factor in Expression of Tooth Movement
Naphtali Brezniak, Noam Protter, Agate N. Krausz, W. Eugene Roberts
The concept for a tooth’s center of resistance (CRes) was introduced about 100 years ago. It is fundamental to the physics of orthodontic biomechanics. The CRes defines the response of a naturally restrained tooth (PDL and alveolar bone) to applied loads. It is typically specified near the center of the bone-supported root. This report describes the dynamic change in the position of the CRes during treatment with fixed appliances (FA) to achieve precise tooth movement with applied force (F) for tipping the tooth and a couple for rotating the root in the plane of the force. The limitation for removable appliances, including clear aligners (CA), is they only readily achieve tipping. A specific set of aligners rarely exceed a treatment efficiency greater than 50% of a programmed clinical simulation like ClinCheck® (Align Technology, Tempe AZ). Removable appliances fail to efficiently control the location of the CRes. (J Digital Orthod 2025;77:46-54)
Where Legacy Meets Innovation: Reflection on the Mershon Award and an AI-Assisted AAO Presentation
Dr. Lexie Y. Lin
Anyone who has devoted themselves to the field of orthodontics has likely heard of the John Valentine Mershon Memorial Award. Established by the American Association of Orthodontists (AAO) in 1960, it is the third oldest honor - following the Ketcham and Hellman Awards - designed to recognize individuals who have made visionary and inspiring contributions to the profession. Dr. Mershon was a direct student of Dr. Edward H. Angle and served as Head of the Department of Orthodontics at the University of Pennsylvania from 1916 to 1925, during which time he developed the innovative removable lingual arch. His influence continues to shape the field…
My Journey in Pursuing a Master’s Degree in Orthodontics in Germany
Dr. Yi-Hsuan Lin
In my early dental training, my specialization focused on prosthodontics. As I gained more clinical experience, I began to realize a key issue: the alignment of teeth significantly affects the quality and success of prosthetic treatment. When teeth are not in ideal positions, even with the utmost effort put into making prostheses, both function and esthetics may fall short of expectations.
This clinical dilemma led me to reflect: if orthodontic treatment could be introduced before prosthetic rehabilitation, moving teeth into more favorable positions, it would enhance the precision of prosthesis design and bring outcomes closer to our shared goal of natural harmony…
A Letter from Dr. Roberts
Dear Chang Family,
I returned home late last night. The flight to San Francisco out of Taipei was late leaving, but there was no problem because I had a several hour layover at SFO. All the luggage made it including the heavy blue trunk full of gifts that all of you so generously bestowed. The lock was destroyed so my big blue trunk has made its last trip. Cheri and I are having treat fun going through all the gifts you sent. Now we must dig into all the photos and videos!
There is no adequate way to thank you for the marvelous generosity. The trips, family togetherness, rose stones, Jimmy & Lily, and the excellent single malt whiskey were really special. The four Beethoven Girls are quite a group! We have so much fun at the spas, shopping and dining…