A radiographic study of the mandibular third molar root development in different ethnic groups.

BACKGROUND: The nature of differences in the timing of tooth formation between ethnic groups is important when estimating age. AIM: To calculate age of transition of the mandibular third (M3) molar tooth stages from archived dental radiographs from sub-Saharan Africa, Malaysia, Japan and two groups from London UK (Whites and Bangladeshi). MATERIALS AND METHODS: The number of radiographs was 4555 (2028 males, 2527 females) with an age range 10-25 years. The left M3 was staged into Moorrees stages. A probit model was fitted to calculate mean ages for transitions between stages for males and females and each ethnic group separately. The estimated age distributions given each M3 stage was calculated. To assess differences in timing of M3 between ethnic groups, three models were proposed: a separate model for each ethnic group, a joint model and a third model combining some aspects across groups. The best model fit was tested using Bayesian and Akaikes information criteria (BIC and AIC) and log likelihood ratio test. RESULTS: Differences in mean ages of M3 root stages were found between ethnic groups, however all groups showed large standard deviation values. The AIC and log likelihood ratio test indicated that a separate model for each ethnic group was best. Small differences were also noted between timing of M3 between males and females, with the exception of the Malaysian group. These findings suggests that features of a reference data set (wide age range and uniform age distribution) and a Bayesian statistical approach are more important than population specific convenience samples to estimate age of an individual using M3. CONCLUSION: Some group differences were evident in M3 timing, however, this has some impact on the confidence interval of estimated age in females and little impact in males because of the large variation in age

Cross-cultural adaptation and validation of the Italian Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ)

Purpose To validate and cross-culturally adapt the Italian version of the Psychological Impact of Dental Aesthetics Questionnaire (PIDAQ) among Italian young adults. Methods After translation, back translation, and crosscultural adaptation of the English PIDAQ, a first version of the Italian questionnaire was pretested. The final Italian PIDAQ was administered to 598 subjects aged 18–30 years, along with two other instruments: the aesthetic component of the index of orthodontic treatment need (IOTN-AC) and the perception of occlusion scale (POS), which identified the self-reporting grade of malocclusion. Structural validity was assessed by means of factorial analysis, internal consistency was measured with Cronbach’s alpha coefficient (a), convergent validity was assessed by means of Spearman correlation, and test–retest reliability was calculated with intra-class correlation coefficient (ICC) and standard measurement error. Criterion validity was evaluated by multivariate and univariate analysis of variance with Bonferroni post hoc tests. Results The a of the Italian PIDAQ domains ranged between 0.79 and 0.92. The ICC was between 0.81 and 0.90. The mean scores of each PIDAQ domain showed a statistically significant difference when analysed according to the IOTN-AC and POS scores. Conclusion The satisfactory psychometric properties make PIDAQ a usable tool for future studies on oral healthrelated quality of life among Italian young adults