Assessment of occlusion and temporomandibular joint after placing preformed metal crowns on all primary molars in children

Placing preformed metal crowns (PMCs) on all eight primary molars at one single clinical visit may disrupt a child's occlusion; the literature regarding the effects on occlusion and temporomandibular joint (TMJ) is scarce.This study aimed to quantify the changes in occlusion using T-Scan III and to investigate whether there was TMJ dysfunction after placing eight PMCs at the same time.In this study, we enrolled children with severe early childhood caries (S-ECC) and dental phobia, who needed eight PMCs to be placed under general anesthesia. The participants underwent occlusal examinations with a computed occlusal analysis system. The vertical dimension of occlusion (VDO) was measured using a dental vertical dimension gauge, TMJ dysfunction signs were recorded by the clinical dysfunction index (Di), and TMJ dysfunction symptoms were recorded using a questionnaire. The data were collected before treatment (T0 ), 1 week after treatment (T1 ), and 1 month (T2 ) and 3 months (T3 ) after treatment during follow-up visits. Repeated-measures analysis of variance and Friedman's test were used for occlusal data analysis. In addition, the Di and symptoms were compared over time using McNemar's test.Forty patients (mean age = 4.25 ± 0.63 years, age range = 3-5 years, 21 boys and 19 girls) were followed up for 3 months. The occlusal contact area 3 months after treatment did not return to the pretreatment status (p = .03). The total of force at the 3-month follow-up visit increased significantly (p = .009) compared with that at the pretreatment. The asymmetric ratio of occlusal force at the 1-month follow-up visit was restored to pretreatment. Concerning the occlusion time, no significant changes were observed for any time intervals (p = .069). The VDO was recovered at the 1-month follow-up visit. The statistical analysis of TMJ dysfunction showed no significant differences in the Di and TMJ dysfunction symptoms before and after treatment (p > .05).After undergoing eight PMC restorations under general anesthesia, occlusal re-equilibration was attained approximately after 1 month. There were no significant signs and symptoms of TMJ dysfunction after treatment.