The Influence of Labio-lingual and Mesio-distal Anterior Tooth Dimensions on Inter-arch Relationships: A Modified Anterior Bolton Analysis

Yelena Akselrod Beygelman
Chair of the Supervisory Committee:
Anne-Marie Bollen, Graduate Program Director
Department of Orthodontics

Introduction: Tooth size and morphology of anterior teeth influence inter-arch relationships. The Bolton analysis uses tooth width to calculate a sum of mandibular to maxillary tooth widths ratio necessary for proper occlusion. Several parameters not factored in the Bolton analysis influence occlusion such as tooth thickness. This study sought to use 3D modeling to develop and assess a tooth size analysis that encompasses labio-lingual thickness as well as mesio-distal width of anterior teeth.

Methods: The role of tooth thickness in inter-arch relationships was studied using simulations in a 3D modeling software (SuresmileTM). To develop a new chart of inter-arch ratios based on tooth thickness, a series of simulations were produced with varying tooth thicknesses and widths. The new ratios were evaluated on records from 50 patients.

Results: Findings from the simulations suggest that the ideal tooth thickness remains approximately 2mm if the overall tooth width of the dentition increases and the inter-arch anterior ratio is maintained. The thickness-adjusted anterior mandibular to maxillary tooth ratio ranges from 0.70 to 0.79 depending on the tooth thickness. This thickness-adjusted ratio provides a superior prediction for the sum of anterior tooth width compared to the Bolton analysis.

Conclusions: Tooth thickness does affect inter-arch tooth width ratios and anterior occlusion. A thickness-adjusted ratio can be used to more accurately predict anterior tooth dimensions necessary to achieve proper occlusion.

Bio: Yelena is originally from Ukraine, and moved to the states at a young age. She grew up in Bellevue, Washington and completed her undergraduate education in Biology at the University of Washington. She then moved to sunny Los Angeles to attend the University of California, Los Angeles for her dental degree, where she met her husband, Leo. Keeping up the Team 1 tradition, she got married in the first year of her orthodontic residency program. Yelena is immensely fortunate to have had the opportunity to return home to the Pacific Northwest to pursue orthodontics at the University of Washington. She is forever grateful to the wonderful faculty for sharing their experience, and for their endless support. She would especially like to thank her loving family and husband, who have been by her side through this journey. Three years have flown by, and she will miss the UW Ortho family. Yelena is looking forward to staying in Seattle after graduation and starting her orthodontic career.

Evaluating Changes in the Inter-Occlusal Space During Orthodontic Retention Stage

Veronica M. Toro
Chair of the Supervisor Committee:
Anne-Marie Bollen, Professor and Program Director
Department of Orthodontics

Introduction: This study measured post-treatment changes in the inter-occlusal space one month and three months after comprehensive orthodontic treatment: “settling”, using 3D images. The effects of patients’ demographics and retention were analyzed.

Methods: Intraoral scans were taken at debond, 1-month and 3-months retainer checks for 90 consecutively finished patients. A heat map was created with a 3D Software to measure the inter-occlusal changes. The changes in the total surface area in range, anterior and posterior areas, retainer type (occlusal coverage or not), age, and gender were compared.

Results: The Total Surface Area in range increased the first month (p<0.001) and from 1 month to 3 months (p>0.05). Anterior and posterior teeth experience changes in the inter-occlusal space during the 3-month period. There was an increase in occlusal contacts for patients wearing retainers without occlusal coverage. There was no influence of gender or age.

Conclusions: During the first month after the removal of orthodontic appliances, there is an increase in total surface area in range. The contact surface area of teeth within the -2mm to 0.25mm range of distance between the upper and lower teeth remains constant. Retainers without occlusal coverage allow changes in the inter-occlusal space.

Bio: Veronica was born and raised in San Juan, Puerto Rico with her parents and big sister. Since she was a little girl, she had two passions: dogs (passion she got from her Mom), and straight teeth (which she definitely inherited from her Grandfather and Dad). Following in her Dad’s footsteps, she decided to become an Orthodontist. Veronica completed Dental School at the University of Puerto Rico School of Dental Medicine. In 2014, she was fortunate to join an amazing group of residents at the University of Washington for her Orthodontics Residency. She is grateful for the constant support, encouragement, education, and guidance the UW Ortho family gave her the past 3 years. Veronica is also very thankful for her family; it has been a very long journey, and she could not have done it without their support. Lastly, she would like to thank her Team 5 for all the support and tell them: “Guys, there is no team like ours! Let’s continue being awesome.”

Characterizing the appearance of ex vivo remineralized white spot lesions with a novel peptide

Sherwin Habibi

Background: White spot lesions (WSLs) are unfortunate post-orthodontic sequelae that compromise the final esthetics of treatment, can result in caries, and can persist indefinitely. Current methods to treat WSLs may promote remineralization, but have not demonstrated consistent improvement with respect to the appearance of the lesion.

Purpose: This study explores the remineralizing potential of a novel peptide, amelogenin-derived peptide 5 (ADP5), in comparison with MI Paste Plus (MIPP) and topical fluoride treatment.

Methods: Artificial WSL lesions were created on ex vivo human molars. Teeth were sectioned into samples and randomly assigned to 1 of 4 arms: (1) a daily regimen of ADP5 solution, (2) a daily regimen of MIPP, (3) a daily regimen of 20,000 ppm fluoride solution, and (4) incubation in an artificial saliva control. Samples were treated for a period of 2 weeks. Photographs were taken prior to and after treatment. Two panels comprising 5 dental professionals and 5 laypersons assessed before-and-after pairs of photographs in a blinded fashion. Scanning electron microscopy was performed on most samples after treatment to assess the subsurface lesion microstructure and the effects of treatment.

Results: After creating WSLs, 11 of these were assigned to the ADP5 group, 12 to the MIPP group, 12 to the fluoride group, and 10 to the control group. The mean improvements assessed by the expert panel were 16%, 16%, 15%, and 8% in the ADP5, MIPP, fluoride solution, and control groups, respectively. The mean improvements assessed by the lay panel were 16%, 13%, 16%, and 8%, respectively. Single factor ANOVA revealed no difference in the amount of improvement across the 4 study groups. SEM images were qualitatively assessed. Samples treated with ADP5 showed an appositional layer of approximately 5 m and a subsurface remineralization depth of 25 m. Control samples did not appear to display any apposition or any remineralization. MIPP and fluoride samples were more variable in their presentation, with subsurface remineralization depths ranging from 0 to 25 m in both groups.

Conclusions: Treatment of WSLs with ADP5 did not produce a significantly greater visual improvement when compared to the other treatment groups or the control over the 2-week period. SEM imaging revealed a more consistently achieved penetrative remineralization in ADP5 groups compared to MIPP and fluoride groups, as well as a thin appositional layer that was often present.

Bio: While Sherwin was born in Halifax, Nova Scotia, his family soon after moved to Ottawa, the beautiful capital city of Canada. There, he went through his formative years, instructed martial arts, and completed his undergraduate degree in Biology at Carleton University. Upon graduation, Sherwin was awarded the Governor General’s Academic Medal for the highest academic standing amongst his peers. He then set out for dental school at the University of Toronto, where he enjoyed immersing himself in all that the program and city had to offer. While in dental school, he developed an interest in orthodontics, and was ecstatic to be accepted to UW Orthodontics.

Calling the faculty by their first names was an uneasy adjustment at first, but Sherwin quickly learned that it reflected the department’s collegiality and warmth. Sherwin feels privileged and extremely proud to have been given the opportunity to complete his orthodontic residency here and to be in such a wonderful environment of excellence and encouragement by its incredible faculty, administration, and support staff. He strongly believes in the noble station of teachers, and hopes to, in some capacity, teach up-and-coming generations of students himself in the future. Sherwin treasures the friendships that he has developed here at UW and is looking forward to continuing them as he moves forward in his career.

Sherwin plans to return home to Canada to practice, where he is excited to enhance the smiles and confidence of his patients. He will continue with his other passions of snowboarding, directing and editing videos, and beatboxing!

3-D Comparison of the shape and position of the condyle before and after Class II correction

Sepideh Torkan

Purpose: The aims of this study were to assess the changes in the shape and position of the condyle in the fossa as well as its position relative to the cranial base before and after Class II correction with the Herbst appliance (HA) or headgear (HG), and to also compare any changes to matched Class I cases.

Methods: Patients were divided into four groups, Class II treated with HA and their matched Class I cases, as well Class II cases treated with HG and their matched Class I cases. CBCTs were obtained before and after treatment in all cases. A total of 122 condyles (left and right) from 61 patients were assessed. 242 landmarks were identified on the condyle and fossa, from which 3-D surface meshes were created. 7 relatively stable landmarks were recorded on the skull to assess the position of the condyle relative to cranial base. Length of the mandible was measured on laterals cephalograms rendered from CBCTs. Principal component, generalized Procrustes, and discriminant function analyses were used to assess shape and position changes.

Results: There were no significant changes in the position of the condyle relative to the cranial base before and after treatment. No significant differences were reported in the anteropostserior or vertical position of the condyle relative to the fossa (P=0.71 and P=079 respectively). There were significant changes in the shape of the condyles when Class II untreated cases were compared to controls. Untreated Class II cases had more internal rotation of the mediolateral long axis of the condyles when compared to Class I cases. There were no significant differences in changes in the length of the mandible between Class II and control cases.

Conclusions: The condyles of all untreated patients, whether they were Class I or Class II initially, did not change their position (within the fossa or relative to stable cranial base structures) when assessed at the end of orthodontic treatment.

Bio: Sepi grew up in Iran with her parents and her older brother and sister. She completed dental school in her hometown where she met her husband, Navid. Sepi became increasingly fascinated by orthodontics during her time in dental school. She started a 4-year orthodontics residency right after finishing dental school and worked as an orthodontist for 8 months before deciding to start a new journey and move to the United States. She was very fortunate to get into the school of her dreams; the University of Washington has given rise to a great number of her orthodontic idols. After two residencies and two countries, she is very excited for the next chapter of her life and is looking forward to starting a career as an orthodontist in Seattle where she now calls home. Sepi is proud to finally be in the ranks of UW alumni and is grateful for all the valuable lessons she has learned from her faculty. She would like to thank her husband, Navid, for his unwavering support and unconditional love. This day would not have come without him!

Mouthguards During Orthodontic Treatment: Perspectives of Orthodontists and a Survey of Orthodontic Patients Playing School-Sanctioned Basketball and Football

Neal Bastian 

Purpose: This study’s objectives were to: 1) examine the beliefs and practices of orthodontists about mouthguard use in orthodontic patients, and 2) survey orthodontic patients currently playing school-sanctioned basketball and/or football about mouthguards.

Methods: Fifteen orthodontists were interviewed about mouthguard use in their patients. Patients from 13 of the offices participated in an online survey about mouthguards. Orthodontic patients (11-18 years old) playing organized school basketball (N=53) and/or football (N=22) completed the survey.

Results: Approximately half of the orthodontists surveyed initiated a discussion about mouthguards with their patients. The boil-and-bite type mouthguard was most commonly recommended by the orthodontists. All football players reported using a mouthguard, as mandated by this sport. Basketball does not mandate mouthguard use and only 38% of basketball players reported wearing one. Mouthguard users most commonly reported having a stock type [football (59%), basketball (50%)]. Players who used mouthguards cited forgetting as the most frequent reason for not always using one. Basketball players who never wore a mouthguard reported that hardly anyone on their team wears one (77%), that it might make it hard to breathe or talk (74%), and that they never thought about wearing one (68%). A greater proportion of football (87%) than basketball (32%) players reported that their coach recommended a mouthguard (p<0.0001).

Conclusions: Orthodontists differ in how they approach mouthguard use by their patients, which likely reflects a lack of evidence-based guidelines. The beliefs, recommendations and practices of orthodontists concerning mouthguard use are discussed. Research directions to improve mouthguard use are suggested.

Bio: Neal was born and raised in Mill Creek, Washington.  He received a Bachelor of Science in Exercise Science from Brigham Young University.  He served a mission for his church in Manila, Philippines and is fluent in Tagalog.  After several years away from home, Neal was grateful to return to Seattle to attend dental school at the University of Washington.  Over the last 7 years at UW, Neal and his wife Michelle have seen their family grow from 1 child to adding two children during dental school and now one more on the way!  Neal would like to share his appreciation for his wife for all of her sacrifices and service.  The Bastian family is thrilled to again call Mill Creek home where Neal will be joining Sullivan Orthodontics, in private practice.