BACKGROUND: During third molar removal, the mandible is supported by a dental assistant (DA) to counter downward forces during surgery, and with sedation, to maintain airway patency. The Restful Jaw device (PEP Design; Saint Paul) provides this support instead of the DA. PURPOSE: This study compared the occurrence of postoperative preauricular and masticatory muscle pain symptoms (PMMPS) between the device and DAs providing mandibular support, using two outcome measures. Secondary aims identify predictors of outcome and providers' opinions of the device. STUDY DESIGN, SETTING, SAMPLE: In this multisite, single-blind, two-arm parallel randomized trial, participants without preoperative PMMPS had surgical removal of third molars, with sedation and bite blocks were randomly assigned to manual support or the device. EXPOSURE VARIABLE: The exposed group was randomly assigned to the device and the nonexposed group to manual support. MAIN OUTCOME VARIABLE(S): The primary outcome was patient-reported PMMPS. Two secondary outcomes were pain assessed with the temporomandibular disorder Pain Screener and providers' views on the device. Outcomes were assessed at 1-, 3-, and 6-month postsurgery. COVARIATES: The covariates are baseline demographics (eg, sex), clinical characteristics (eg, eruption status), and third molar surgeries. ANALYSES: For occurrence of pain, generalized estimating equations assessed differences between groups. Logistic regression analysis assessed predictors of pain at 1 month, per the Screener. The level for statistical significance was 5%. RESULTS: Enrollment was 86 and 83 participants in the device and DA groups, respectively. The average age was 20.8 years; the majority were female (65%) and Caucasian (66%). The retention rate was ≥ 95.9%. The groups did not differ significantly for occurrence of pain using the primary and secondary outcome measures at any follow-up (P  ≥  .46). Fully impacted molars were associated with occurrence of pain (odds ratio = 3.44; 95% confidence interval 1.49-7.92; P = .004). CONCLUSION AND RELEVANCE: Occurrence of pain using the primary and secondary outcome measures did not differ significantly between groups at any follow-up and was associated with removal of fully impacted third molars. Four out of five surgeons reported wanting to use the device on a regular basis when performing this procedure in sedated patients.