Background: Root resection is one treatment option for preserving molars with furcation involvement. This study evaluated the prognosis of root-resection therapy retrospectively and examined the factors influencing the survival rate of resected molars.
Methods: Root-resection therapy was performed on 691 molars in 579 patients. The associated factors were examined from 342 of 402 molars that had been followed up for >1 year. Survival analysis was used to statistically analyze the factors.
Results: Over the past 10 years, 102 of 342 cases (29.8%) failed. The factors were classified into four groups and analyzed to determine their influence on the survival rate of the resected molars. Regarding the resection-related factors, the molars resected because of periodontal problems had a higher survival rate than those resected because of non-periodontal problems (tooth fracture, dental caries, and endodontic problems; P = 0.0097). Patient- and tooth-related factors had no effect on the survival rates. Among the site-related factors, only the amount of bone support of the remaining roots at the time of surgery had a significant effect on the survival rate in the group of molars with periodontal problems (P = 0.0269).
Conclusions: Root resection to treat periodontal problems had a better prognosis than for non-periodontal problems. To achieve a good result, it was important that the remaining roots had >50% bone support. This guideline may help to improve the predictability of root-resection therapy.