Reliability of different methods for measuring the inclination of the maxillary canines on panoramic radiographs

Objectives – To test the reliability of 4 different methods of measuring maxillary canine inclination (CI) on panoramic radiographs, and to determine whether examiner experience level influenced these measurements under ideal experimental conditions. Setting and Sample Population – The sample consisted of 20 highquality panoramic radiographs obtained under standardized conditions using the same radiological apparatus. Material and Methods – Canine inclination (CI) was measured as either the angle formed by the canine long axis and the midline (method A), a line passing through the suborbitary points (method B), the most superior points of condyles (method C) or the mesiobuccal cusp tip of the first molars (method D). Measurements were made at initial observation (T1) and after 3 months (T2) by 5 experienced orthodontists and 5 undergraduate dental students. Results – Mean T1-T2 differences for the measurements were close to zero, with no relationship between their magnitude or direction for each method. Intra-rater reliability was excellent, with the lowest values being observed for method B and the highest for method C. No influence of the examiner experience level was detected. Conclusion – The four methods used in this study to measure CI showed excellent intra-rater and inter-rater reliability, irrespective of examiner experience level. Method B was the least reliable and method C the most reliable, if compared with the others.