CEPHALOMETRIC FLOATING NORMS FOR THE MMBP-WITS AND b ANGLE AMONG THE CHENNAI POPULATION

Abstract

AIM: The purpose of this study was to attain floating norms for the MMBP-Wits and 𝛽 angle in adult Chennai population that can aid in proper diagnosis and treatment planning of different cases. Methods: Lateral cephalograms were acquired from 100 subjects (50 males and 50 females; mean age: 18-25 years) with pleasant profile and well-balanced and a near-ideal occlusion. Land mark identification and tracings were carried out manually on 0.003’ thickness acetate film. The ANB angle, the 𝛽-angle, the MMBP-Wits were measured. Four Other angular cephalometric parameters which included the SN/PP, SN/MP, SNA, and NSB angles were also measured. Multiple regression models were used to quantify the correlation of the ANB angle, MMBP-Wits and 𝛽 angle with each other and also with four other angular cephalometric parameters mentioned above. RESULTS: All the three cephalometric parameters of antero-posterior maxillary-mandibular relationship had considerable association with the explanatory variables with 𝑅2 range from 0.183 to 0.212 for the ANB angle and the MMBP-Wits, respectively. The ANB angle was considerably related with all the explanatory variables. In particular, the NSBa, SNA, and SN/MP angles were certainly associated with the ANB angle, whereas the SN/PP angle was inversely associated. On the contrary, both the 𝛽 angle and MMBP-Wits were considerably associated with SNA and SN/MP angles. These explanatory variables showed positive and inverse association with the MMBP-Wits and the 𝛽 angle. CONCLUSION: (i) The ANB angle is prone to have considerably more geometrical distortion as compared to the MMBP-Wits and the 𝛽 angle. (ii) Floating norms have been given to individualize the reference values for both the MMBP-Wits and 𝛽 angle.