Comparative analysis of three dimensional position discrepancy of centric relation-maximum intercuspation in patients with mandibular deviation

Abstract:

Objective：To analyze the three dimensional characteristics of condylar position between centric relation（CR） and maximum intercuspation（MI） in patients with mandibular deviation and to discuss its influence on orthodontic treatments of dental maxillofa－cial deformities. Methods：Thirty-four patients with mandibular deviation were taken as experimental group and fifty patients with non-deviation as control group. Experimental group was then divided into two groups according to the existence of temporomandibular joint disorder（TMD）. CR/MI occlusions and occlusal interferences of CR position were recorded respectively. Condylar positions of CR and MI were measured respectively by measures condyle displacement（MCD） and the proportion of occlusal interferences and CR-MI discrepancy，as well as the offset in condylar position between CR and MI in three dimensional direction were compared. Results：（1）Percentages of occlusion interferences in experimental and control group were 94.12% and 72% respectively with statistical differences（χ2=6.421，P=0.010） and the occlusion interferences of both groups were located at the posterior teeth，accounting for 91.18% and 68% respectively；（2）Percentages of CR-MI discrepancy in experimental and control group were 79.41% and 12.00% respectively（ χ2=38.59，P=0.000）；（3）In the experimental group，there was no significant difference in the percentage of CR-MI discrepancy（ χ2=0.167，P=0.687） and the amount of displacement of CR-MI in vertical（t=0.283，P=0.779） or sagittal（t=-0.743，P=0.463） plane between deviated and non-deviated side（P >0.05）. There was no significant difference in the amount of displacement of mandible and ＣＲ-ＭＩ discrepancy in three dimensional direction between TMD group and non-TMD group（P >0.05）. Conclusions：Patients with mandibular deviation show a higher tendency to suffer occlusal interferences and CR-MI discrepancy，so it is necessary to analyze the consistency of CR-MI in patients with mandibular deviation and to make a treatment plan in the ideal position of jaw.