Condylar repositioning in mandibular retrusion

Statement of problem. There has been debate about which anteroposterior max illomandibular relationship should be used in fixed and removable prosthodo ntics for patients without a definite maximal intercuspation. The choice ha s important implications for complete denture fabrication in which any guid ance to the previous dentulous maximal intercuspal position is missing. Purpose. This study was designed to estimate the posterior displacement tha t takes place at the mandibular condyles and occlusal surfaces when the man dible is moved from maximal intercuspal position to the most retruded mandi bular position. Material and methods. Articulated occlusal models of 18 subjects with a nat ural dentition and well-defined maximal intercuspation were studied. Models were rearticulated in retruded contact position, and the original vertical dimension of occlusion was restored by eliminating all interfering occlusa l contacts on the retruded path of closure. Measurement of change in condyl ar position was estimated using a SAM2 articulator with condylar position i ndicator. Posterior displacement at the occlusal surfaces was measured with a traveling microscope. Results. Condylar analog retrusion in the horizontal plane at the initial r etruded contact position varied from 0.6 to 2.4 mm (mean 1.0 +/- 0.4 mm); h owever, after occlusal adjustment to restore the original vertical dimensio n of occlusion, retrusion was reduced to a range of 0 to 0.4 mm (mean 0.2 /- 0.1 mm). Retrusion at the occlusal surfaces was found to vary from 0.4 t o 1.5 mm (mean 0.7 +/- 0.3 mm) at retruded contact position; however, after occlusal adjustment, retrusion was reduced to a range of 0 to 0.5 mm (mean 0.2 +/- 0.1 mm). Conclusion. Posterior displacement at both the occlusal surfaces and the co ndyles was small when interfering occlusal contacts on the retruded path of closure were removed.