The Etiological Study On Occlusal Contacts In Temporomandibular Disorders

Objective:To investigate the characters of occlusal contacts of the temporomandibular disorders,and analyse the relationship between the occlusal factors and craniomandibular index,to discuss the effect of occlusal contacts to TMD clinical symptoms.Methods:18 cases with TMD were choosen and examined according to Friction clinical inspection sheet of temporomandibular joint to calculate craniomandibular index(CMI).The occlual contact characters of 18 cases and 16 controls were measured with T-ScanⅡsystem in the intercuspal occlusion position,the protrusive movement,the retruded movement as well as lateral movement.Then analysis was carried out statistically about the difference of two sets and the relationship between the occlusal factors and CMI.Results:1.The difference of percentage of occlusal force in TMD group was greater than that in control group and there are significant difference between them.The offset of center occlusal force of TMD group mainly concentrated in grade 2(60%≤percentage of left or right＜70%),while control group in grade 1(50%≤percentage of left or right＜60%).2.The incidence of premature contact,retruded occlusal interference and lateral occlusal interference in TMD group were higher than those in control group and there are significant difference between them.While there was no singnificant difference about protrusive occlusal interference between the two groups.3.The occlusion time,protrusive disclusion time and lateral disclusion time in TMD group were longer than those in control group and there are significant difference between them.4.There was moderate positive linear correlation between occlusion balance,occlusion time and CMI,while lower correlation between protrusive disclusion time,lateral disclusion time and CMI.Conclusion:1.There were poor occlusal balance and higher incidence of premature contact,retruded occlusal interference and lateral occlusal interference as well as prolong of occlusion time and disclusion time in TMD group.2.Occlusion balance,premature contact,retruded occlusal interference and lateral occlusal interference were closely related to TMD.3.Occlusion balance and occlusion time were important references for lesion degree and therapeutic efficacy of TMD,which could instruct clinical occlusion therapy.