Edwin H Yen

Objectives: To evaluate the diagnostic accuracy of near infra-red imaging (NIRI) technology of iTero Element 5D intra-oral scanners (index test) by comparing it to bitewing radiography (clinical reference standard) for detecting proximal surface enamel caries (target condition). Methods: We conducted a diagnostic study on 42 consecutive patients (22 males & 20 females) who presented for orthodontic treatment at the University of British Columbia (UBC). Consenting individuals ≥12 years of age received intra-oral digital scanning using iTero Element 5D scanners and full-mouth bitewing radiographs (BWRs). Two experienced pediatric dentists independently evaluated the non-restored proximal surfaces on BWRs and NIRI images for the presence/absence of initial enamel caries. Results: The prevalence of the target condition in the sample population was 5.8%. Of 1110 proximal surfaces included in the analysis, the diagnosis of the target condition was confirmed in 65 surfaces based on BWRs. The index test showed a sensitivity of 60.0%, specificity of 97.7%, positive predictive value of 61.9%, and negative predictive value of 97.5%. The inter- and intra-examiner reliability for BWRs and NIRI images were 0.78, 0.97, 0.85, and 1.0 respectively. The Area Under the Curve (AUC) value for the index test was 0.78 which can be considered acceptable in terms of the test’s ability to distinguish between positive (caries) and negative cases (no caries).Conclusions: The index test showed high specificity and negative predictive value; therefore, it has potential as a non-ionizing screening tool for the detection of proximal surfaces without enamel caries in permanent teeth, particularly in adolescents with a moderate/high caries risk.Acknowledgements: This project was supported by a 2021 Align Research Award (AWD-020121).

View record

Objectives: The European colonization of Canada has resulted in generations of oppression and transgenerational trauma for Indigenous people. The long-term consequences of colonization include well-documented worse health outcomes, including poorer oral health and increased severity and occurrence of malocclusion for Indigenous people. The Canadian government has treaty obligations to provide medical coverage to Indigenous people. Through the Canadian government’s Non-Insured Health Benefits program (or the First Nations Health Authority in British Columbia), tier-three medical benefits are covered, including dental treatments and orthodontics. However, the criteria for being approved for orthodontic coverage under this program are extremely stringent and require a complicated pre- determination process. The purpose is to evaluate the extent to which the predetermination process is a barrier to Indigenous youth in Canada obtaining government funding for orthodontic treatment. Methods: Interviews were conducted to explore the perspectives of office managers of orthodontic offices, orthodontists, administrators of orthodontic-related associations including the CAO and the FNHA. International orthodontists were also interviewed to compare government-funding orthodontics around the world to Canada's model. The interviews used a topic-guided, standardized, open-ended interview format. The transcribed interviews were analyzed for general themes. Results: Eight themes emerged from 13 interviews: 1. Excessive use of staff, 2. Administrative barriers, 3. Issues with Jordan’s Principle, 4. Family expectations, 5. Qualifying issues, 6. Problems with phase 1, 7. Transparency and accountability, and 8. Focus on expense. Conclusions: This study suggests that there are significant administrative barriers associated with the orthodontic predetermination process encountered by Indigenous Canadian youth seeking funding for care through the Non-Insured Health Benefits Program, or the First Nations Health Authority in British Columbia. Some recommendations for reducing these barriers are enumerated.

View record

Objectives: Non-thermal plasma (NTP) has been used to modify enamel and dentin surfaces and improve the interfacial bonding of dental composite restorations. NTP is shown to cause super hydrophilic surface by decreasing the contact angle measurements and improve the quality of the adhesive - enamel and adhesive - dentin interface. We sought to determine the effects of NTP treatment on the bond strength of brackets to enamel. We investigated the application of NTP alone and in combination with phosphoric acid (PA) etching and assessed the outcomes after 24 hours and 1 month.Methods: 84 extracted pre-molars washed and disinfected were divided into 2 broad groups: No-treatment and Treatment group. No - treatment group consisted of 12 premolars on which orthodontic bracket bonding was performed without any surface - treatment except for polishing with pumice. Treatment group consisted of 72 premolars which were divided randomly into 3 main groups of 24 premolars each. These groups were Group 1: PA Etch (30s), Group 2: PA Etch (30s) + NTP (30s) and Group 3 NTP (30s). The bonded teeth were stored in water at 37° C and tested in shear mode after 24 hours and 1 month (n= 12). The fracture mode and adhesive remnant index were determined on de-bonded surfaces. SEM pictures were taken from enamel surfaces after each treatment. Results: During the first 24 hours of testing, SBS was maximum with Etch+ NTP and Etch treated group followed by NTP group ( P
View record

Objectives: To determine the relationships between tooth tipping and occlusal curvature patterns in serial extraction (SE) cases versus late premolar extraction (LPE) cases and controls. Methods: Mandibular dental casts and cephalometric radiographs were collected from 90 subjects (30 Class I controls, 30 SE cases, 30 LPE cases) at 3 time points: baseline (T0) for controls and SE, after natural drift/pre orthodontics (T1) for controls, SE, and LPE, and after comprehensive orthodontic treatment (T2) for the SE and LPE groups. The casts were scanned and rendered as virtual models. 12 cusp tips (4 incisors and 2 first molars) were digitized and the occlusal curves were measured using Rhinoceros by fitting a sphere to the landmarks (least-squares method). Radiographs were digitized and the long axes of the central incisor, canine, and first molar were landmarked and related to palatal plane to determine the direction and amount of tipping. Results: The SE group differed significantly from the other two groups at T1, with smaller radii in 2/3 outcomes. From T0-T1, the SE group showed a tendency for the incisor and canine to tip distally, while the molar tipped mesially. From T1-T2, the SE group had smaller radii versus LPE and demonstrated mesial tipping of the incisor and canine angulations, with the molar tipping distally. Conclusions: SE cases tend to have steeper occlusal curves (smaller radii), post tooth drift and after orthodontic treatment as compared to the other groups. In general, orthodontic treatment, post SE, involved incisor and canine proclination, as well as molar uprighting. SE is unlikely to save more than 4-6 months of active treatment due to the time needed to correct the increased occlusal curvature that results from this procedure.

View record

Introduction: The aims of the cross-sectional study were to determine the prevalence of malocclusion and orthodontic treatment need according to the Index of Complexity, Outcome, and Need (ICON) among schoolchildren of the Aboriginal Island Community of Haida Gwaii in Northwestern British Columbia, Canada.Methods: Out of 535 schoolchildren, 215 (90 boys and 125 girls) agreed to participate in the clinical examination. An examiner, trained in occlusal indices, assessed orthodontic treatment need in children employing the ICON score and the ICON complexity grade. In addition, a questionnaire was modified and used to measure the schoolchildren’s expectations of and self- perceived need for orthodontic treatment. Out of the 215 schoolchildren that were clinically examined, 192 were old enough to comprehend the questions in the questionnaire and were capable of completing the questionnaire without any assistance.Results: The mean age (N=215) was 12.9±2.8 years. Of the examined schoolchildren, 67% have Aboriginal ancestry (at least one parent is Aboriginal). The mean ICON score was 43.5±26.2. There were no statistically significant differences in ICON scores regarding gender (t-test, P=0.207), ethnicity (t-test, paternal ethnicity P=0.886 and maternal ethnicity, P=0.389), or school (ANOVA with Post Hoc Bonferroni Adjustment P=0.317). Overall, 43.7% of the schoolchildren needed orthodontic treatment (ICON > 43). Based on the ICON complexity, 31% of the schoolchildren had moderate to very difficult malocclusions to treat. Adolescents (N=192) with higher ICON complexity scores (more complicated malocclusions) felt a greater need for orthodontic treatment, for extractions, that treatment would give them confidence, and that they were willing to be treated either on island or off island (One way ANOVA with Post Hoc Bonferroni Adjustment, P
View record