Clinical assessment of occlusion and temporomandibular joint after placement of preformed metal crowns for primary molars

To explore the effect on children's occlusion and temporomandibular joint (TMJ) after placement of preformed metal crowns and provide a reference for the restoration of defective primary molars.

A total of 39 children who underwent all primary molar metal crown restorations under general anesthesia were enrolled. The participants underwent occlusal contact area, percentage of total occlusal force, asymmetric ratio of occlusal force and occlusal contact time examinations with the T-scan computerized occlusal analysis system. Vertical dimension of occlusion (VDO) was measured using a dental vertical dimension gauge. TMJ dysfunction signs were recorded using the modified clinical dysfunction index (Di), and TMJ dysfunction symptoms were recorded using questionnaires. All data were collected at pretreatment, 1-week, 1-month, 3-month, and 6-month follow-up visits.

The occlusal contact area at the 3-month and 6-month follow-up visits returned to the occlusal contact area of pretreatment, and the difference was statistically significant (P>0.05). Compared with pretreatment, the percentage of total occlusal force at the 3-month and 6-month follow-up visits increased significantly, and the difference was statistically significant (P<0.05). The asymmetric ratio of occlusal force and the occlusal contact time were significantly decreased at the 6-month follow-up visit (P<0.05). The vertical dimension of occlusion recovered after one month of treatment (P>0.05). The final statistical analysis of the TMJ assessment showed that there was no significant difference in the clinical disorder index and TMJ dysfunction symptoms before and after treatment (P>0.05).

After undergoing all primary molar metal crown restorations, occlusal re-equilibrations were attained after approximately one month. The percentage of total occlusal force and occlusal stability were significantly increased after six months of treatment, without significant temporomandibular joint dysfunction.