Comparing Four Cephalometric Methods Used to Evaluate the Change in the Lower Incisor Inclination

Abstract

Aim: The assessment of change in the lower incisor inclination using cephalometry during any orthodontic treatment is used to determine the treatment outcome. The inclination change is measured using the lower border of the mandible even though it is subjected to remodeling in growing children. We have used Bjork’s superimposition technique using “stable structures” to eliminate these growth changes. In this study, we have evaluated if there is any major difference between three routinely used methods to estimate the lower incisor inclination change influenced by orthodontic treatment (gonion-gnathion, gonion-menton, and tangent drawn to the lower border of the mandible) in contrast to Bjork’s superimposition technique. Materials and Methods: This study was performed using the lateral cephalograms of total of 39 subjects undergoing orthodontic treatment using fixed appliances, aged 12–16 years at the beginning of the treatment. The pretreatment and mid-treatment cephalograms of these subjects were evaluated with a gap of at least 1 year between the two radiographs. Patients who had undergone lower incisor extractions were excluded from this study. Results: The ICC was calculated using Bjork’s superimposition technique as references and subsequently the other techniques were compared. The linear regression model showed good ICC between all methods, with ICC being 0.92 for Go-Me, 0.94 for Go tangent, and 0.88 for Go-Gn. All the three methods showed a significant correlation with Bjork’s method. Conclusion: The data in the current study showed that there was no significant difference in the findings obtained by Bjork’s superimposition method when compared to other techniques. Furthermore, remodeling of the lower border of the mandible showed no significant changes in the investigated time frame.