Rotation of the upper first molar in Class I, II, and III patients

Objective: The aim of this study was to evaluate the mean rotation of the upper first molar (U1 st M) in cast models from nontreated patients presenting: Class I, skeletal Class II, dental Class II, and skeletal Class III, comparing with Class I orthodontically treated patients. Materials and Methods: One hundred cast models were evaluated with five groups, composed of nontreated Class I ( n = 20), dental Class II ( n = 20), skeletal Class II ( n = 20), skeletal Class III ( n = 20), and treated Class I ( n = 20). Measurements were taken from photocopies of the upper arches. The angle formed between a line crossing the mesiopalatal and the distal-buccalcusps of the U1 st M and a line traced on mid palatal junction were measured in all samples. Results: One-way variance analysis showed that dental Class II group presented great mean rotation of the 1 st molar (x = 78.95°, SD = 6.19) ( P Conclusions: The skeletal Class II and skeletal Class III groups showed similar mean position of the 1 st molar, presenting rotation in approximately 50% of the patients. It can be concluded that upper molar rotation occurs mainly in dental Class II patients and shows higher mesial rotation angle.