The reliability of assessing rotation of teeth on photographed study casts

Objective: To examine the intra- and interexaminer reliability of assessing rotation of teeth on photographed study casts. In addition, the reliability parameters of two examiners scoring in mutual consultation were compared with the reliability parameters by one observer.

Materials and Methods: Standardized photographs of sets of maxillary and mandibular plaster casts of 10 patients before treatment (T1), after treatment (T2), and a long time after retention (T3) were digitized. Tooth rotation was assessed relative to a correct position in the ideal dental arch form. A computer analysis program was used to process the measurements. Two examiners assessed each study cast twice with a washout period of 3 weeks. A third examiner assessed each cast, together with one of the other examiners. The intra- and interexaminer agreements were calculated using intraclass correlation coefficients (ICCs). Wilcoxon signed-rank tests were used to determine significant differences between the intra- and interexaminer reliability coefficients of the three examiners.

Results: The ICCs ranged from 0.430 to 0.991. Incisors showed the highest ICCs and molars showed the lowest ICCs. Intraexaminer ICCs of the experienced examiners were significantly higher than those of the examiner with less experience. No significant differences in the reliability between a single examiner and the combination of two examiners were found.

Conclusion: The method of assessing tooth rotation in the present study has proved to be reproducible, except for the molars. This method can be helpful for clinicians assessing tooth rotation from photographed study casts.