Abstract:

Objective To investigate the effects of occlusal rehabilitation on chewing patterns of patients with extensive tooth wear. Methods 29 patients with severe tooth wear were selected and divided into two groups: GroupⅠwith complete posterior tooth support（15 cases）and group Ⅱ with one- side or both side posterior support lost（14 cases）. 15 normal old persons were also selected as control group. The surface electromyography（EMG） of masseter（MM）, anterior temporalis（TA） and posterior temporalis（TP） during chewing movement were recorded in the stage of pre- treatment, 1 month after temporary restoration and 1 month after permanent restoration. The EMG activity, total cycle duration（TCD） and ratio of activation period to relaxation period（AP/RP） of chewing cycles were measured and compared. Results 1）Before treatment, the TCD of these two groups were longer than normal group, but the differences were not significant（P>0.05）. All of the AP/RPs of MM, TA and TP in group Ⅱ were significantly higher than that of normal group（P<0.01）, and EMG activity of TA of group Ⅱ was significantly lower than normal（P<0.05）. 2）After temporary restoration, the TCD of both groups were slightly shortened, while the AP/RP of these two groups were significantly decreased. EMG activities of MM and TP in groupⅠwere both significantly lower than that in pre- treatment stage. 3）After permanent restoration, the TCD of groupⅠwere significantly lower than that in temporary restoration stage（P<0.01）. In group Ⅱ, the TCD was continuously slightly shortened, while the AP/RP were significantly lower（P <0.01） and EMG activities were significantly higher（P<0.01）than that in the temporary restoration stage. Conclusion Occlusal rehabilitation could obviously change the chewing patterns and the EMG activities of patients with severe tooth wear.

Key words: severe tooth wear, chewing pattern, electromyography, occlusal rehabilitation