Molar Distalization using NiTi Coil Spring in High Mandibular Angle Cases

Previous studies have shown that molar distalization using Niti closed coil springs is effective, but increased vertical dimension was a disadvantage. Also, upper incisor flaring was also reported as a reciprocal result of upper molar distalization. Objectives: The purpose of this study was to evaluate the skeletal and dental changes after upper first molar distalization using Niti closed coil spring and Nance holding arch for anterior anchorage in cases with high mandibular plane angle. The null hypothesis was that there is no change in the vertical dimension and upper incisor position after upper first molar distalization. Materials and Methods: Pre – and post- upper molar distalization lateral cephalometric radiographs of ten adolescent cases (12-15 years of age) were used in this study. All radiographs were corrected for magnification distortion and traced using regular tracing techniques. Overall as well as maxillary and mandibular superimpositions of the pre- and post molar distalization were performed. Ten linear and angular measurements were obtained and all the data were statistically analyzed using paired t-test. Results: The results showed that molar distalization achieved was 3.5 mm + 1.4 mm and slight but not statistically significant increase in the vertical dimension before and after treatment (P< 0.05), as well as labial movement of the upper incisor (P < 0.05). Conclusion: In conclusion, upper molar distalization with Niti open coil spring can provide the needed arch length in cases with high mandibular plane angle without adversely affecting the skeletodental pattern of these patients.