Applicability of Yen and W Angle Cephalometric Norms in the Bodo Tribal Population of Assam: A Comparative Study

Evaluating sagittal skeletal relationships is essential in orthodontic diagnosis and treatment planning. The newer cephalometric measures, Yen angle and W angle, depend on stable skeletal landmarks and are less influenced by jaw rotation or cranial base variations.

This study aimed to compare the values of the Yen and W angles in the Bodo tribal population of Assam (North Eastern State of India) with the established norms proposed by Neela et al. and Bhad et al. across skeletal Class I, II, and III patterns.

Pretreatment lateral cephalograms of Bodo individuals were analyzed to measure the Yen and W angles in Class I, II, and III skeletal relationships. The results were statistically compared with the original normative data using independent t-tests.

The mean Yen angle values for the Bodo population were 123.5° for Class I, 114.7° for Class II, and 132.65° for Class III. Compared to a study by Neela et al., significant differences were found in Class I (P = 0.007) and Class III (P = 0.018), but there was no significant variation in Class II (P = 0.941). The W angle values for the Bodo group were 55.1° for Class I, 50.1° for Class II, and 62.3° for Class III, with Class III showing a statistically significant increase compared to Bhad et al. (P < 0.001). The differences in Class I and II were not statistically significant.

The Bodo tribe exhibits distinct sagittal profiles particularly in Class I and III, underscoring the inadequacy of generalized cephalometric norms and the need for ethnic-specific reference values.