Assessment of the role that second molars play in bite-opening during orthodontic treatment in adolescents : a retrospective, cephalometric study

• Main Author: Trockel, Christopher
• Format: Others
• Published: NSUWorks 2013
• Subjects: Dentistry; Orthodontics and Orthodontology
• Online Access: https://nsuworks.nova.edu/hpd_cdm_stuetd/46; https://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1058&context=hpd_cdm_stuetd

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Abstract ASSESSMENT OF THE ROLE THAT SECOND MOLARS PLAY IN BITE-OPENING DURING ORTHODONTIC TREATMENT IN ADOLESCENTS: A RETROSPECTIVE, CEPHALOMETRIC STUDY DEGREE DATE: DECEMBER 6, 2013 Christopher B. Trockel, D.D.S. COLLEGE OF DENTAL MEDICINE NOVA SOUTHEASTERN UNIVERSITY Thesis Directed By: Shiva Khatami D.D.S., Ph.D, Committee Chair Mark Hall, D.D.S., Committee Member Abraham Lifshitz, Committee Member Objectives: This study aimed to investigate the role that second molars play in increasing the facial vertical dimension by comparing vertical changes experienced in growing patients, who had their second molars incorporated into the orthodontic appliance, with those that did not. The study investigated associations between the vertical changes experienced through treatment and the initial vertical classification of the patients (normo-, hypo-, and hyperdivergent). Background: Many studies have investigated the changes in the vertical dimensions that occur in orthodontic treatment. It has been shown that almost all orthodontic appliances produce extrusion whether desired or not. In theory, this extrusion may lead to an increase of the skeletal vertical dimension. Conventional wisdom says that second molars play a significant role in vertical control during treatment. Therefore, some practitioners advocate viii incorporating the second molars as soon as possible in treatment to help open the bite. It is also thought that it may be wise to not incorporate the second molars during treatment at all in cases with an open bite tendency. Methods: Eighty de-identified pre-treatment cephalometric radiographs (40 with second molars bonded and 40 without second molars bonded) from growing patients treated at the orthodontic clinic at Nova Southeastern University were analyzed and compared to their post-treatment analogs. Twelve linear and angular measurements were made (overbite, maxillary molar to palatal plane, mandibular molar to mandibular plane, upper anterior dentoalveolar height, lower anterior dentoalveolar height, upper anterior facial height, lower anterior facial height, total posterior facial height, lower posterior facial height, UAFH/LAFH ratio, mandibular plane angle, and Y-axis). Results: The results indicated that the vertical dimension was not significantly altered based solely on whether or not the second molars were incorporated into the orthodontic appliance. Changes experienced by both groups (bonded and non bonded) and all three subgroups (hypo-, normo-, and hyperdivergent) were consistent with what would be expected for growth alone. Conclusion: Bonding second molars in a growing population during orthodontic treatment does not significantly affect the vertical dimension, regardless of the patient's initial skeletal vertical classification.