Effect of maxillary molar distalization on mandibular condylar pathways

INTRODUCTION: The objectives of this study were to determine whether maxillary molar distalization with a Pendulum appliance affects mandibular condylar pathways and whether quantitative axiographic measurements and tracings can measure these changes. METHODS: Twenty Dental Class II subjects, aged 11.5–15.5, were selected for maxillary molar distalization with a pendulum appliance. Before treatment open-close, protrusion–retrusion, and left and right mediotrusion movements were recorded for each subject. Axiography was repeated after molar correction to Class I and appliance removal. The differences between pre-treatment and post-treatment data were determined and analysed with paired t-tests. RESULTS: The open–close curve coefficient increased 0.03 for left excursion (p < 0.033), 0.03 for left incursion (p < 0.008) and 0.04 for right incursion (p < 0.001). The protrusion–retrusion left reproducibility index was reduced 0.29 mm2/mm (p < 0.001) and the right reproducibility index of 0.65 mm2/mm (p < 0.001). The left mediotrusion movement left quantity was reduced 1.49 mm (p < 0.001). The right mediotrusion movement right quantity was reduced 1.07 mm (p < 0.001). CONCLUSION: Following Pendulum appliance treatment, for the open–close movement, the increases in the Kobs curve coefficient are indicative of a more physiologic condylar tracing. For the protrusion–retrusion and left and right mediotrusion movements the changes in both quantitative axiographic values and curvature deviation are indicative of a less physiologic condylar tracing as defined by Kobs.