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.