This study was conducted to determine if the completeness of the root formation of mandibular third molars prior to removal affected clinical and health-related quality of life (HRQOL) recovery.Data from HRQOL responses from patients and clinical outcome data were available after third molar surgery conducted by surgeons in community practice and academic centers. The root development of each mandibular third molar on presurgery panoramic radiographs for these patients was assessed by trained clinician observers. Patients were categorized as those with complete root formation (both mandibular third molars had 100% completely formed roots) or as those with incomplete root formation (at least 1 mandibular third molar not completely formed). The proportion of patients who experienced delayed clinical or HRQOL recovery that exceeded a clinically relevant criterion value were compared for these 2 groups of patients using chi2 statistics. Level of significance was set at 0.05.Both mandibular third molars had 100% completely formed roots in 118 patients; at least 1 mandibular third molar was not completely formed in 218 patients. If patients had a mandibular third molar with roots less than 100% complete, they more likely: were female (65% vs 58%), were less than 25 years old (95% vs 54%), P < .01, and had not finished high school (59% vs 28%), P < .01. For those with incomplete root formation, bone removal for both mandibular third molars was more likely (84% vs 67%), P < .01, and the surgeons' overall estimate of degree of difficulty was greater (14/28 vs 12/28), P = .02. Median surgery time did not differ between groups. The proportion of patients who experienced delayed clinical or HRQOL recovery did not differ between the incomplete and complete root formation groups.Incomplete lower third molar root formation presurgery may not be a predictor of better or worse clinical or HRQOL recovery after surgery. Other clinical, demographic, and health indicators should influence surgeons' recommendations and patients' decisions regarding third molar treatment including surgery.