Maxillary first premolar inclination in 8- to 11-year-old children: An observational cross-sectional study on panoramic radiographs

Introduction: In this study, we examined first premolar inclination in a large sample. Methods: First premolar inclination, canine inclination, and mesiodistal location were measured on 797 panoramic radiographs of orthodontically untreated children (ages, 8-11 years; 381 boys, 416 girls). The sample comprised 1496 premolars and 1496 canines. A linear mixed-effects model was used to determine the contribution of age, sex, canine inclination, canine sector location, second molar maturational stage (D-G), and dental arch side on premolar inclination. Results: First premolar inclination values (medians and interquartile ranges) were 12.76 (8.12- 19.05) at 8 years, 11.82 (7.87-16.04) at 9 years, 10.40 (6.38-15.46) at 10 years, and 9.03 (5.42- 12.81) at 11 years; 13.86 (8.60-18.78) at stage D, 10.56 (7.39-14.77) at stage E, 10.43 (6.08-15.09) at stage F, and 8.00 (4.62-10.74) at stage G. The following equation was selected (Akaike information Q1 criteria 5 424.99): first premolar inclination 5 –2.211 1 2.240 (8 years) 1 1.363 (9 years) 1 0.955 (10 years) 10.387 (canine inclination) 1 0.902 (right side) 1 2.320 (stage D) 1 6.320 (sector 1)1 5.446 (sector 2) 1 3.803 (sector 3). There was no difference between percentiles constructed by age and maturational stage. Conclusions: First premolar inclination decreases during the mixed dentition and is moderately correlated with canine inclination.