Long-term retention and prognostic factors in repaired vertically root-fractured teeth: A retrospective cohort study

Tooth extraction due to root fractures has recently been increasing. Preserving fractured teeth is clinically important to prevent progressive tooth loss and subsequent occlusal collapse. In this retrospective cohort study, we aimed to evaluate long-term tooth retention after root fracture repair and identify prognostic factors associated with retention outcomes.

The participants were patients who were treated for fractured teeth at Niigata University Hospital in Niigata, Japan from 2003 to 2022. Tooth extraction was defined as the study endpoint. The effects of age, sex, location of teeth, presence of adjacent teeth, Eichner's classification, Miyachi's occlusal triangle, and fracture type were analyzed.

In total, 330 root-fractured teeth of 264 patients were analyzed. Kaplan-Meier analysis demonstrated retention rates of 82.4% at 3 years and 70.1% at 5 years after repair, with a median retention period of 8.1 years. Log-rank tests showed that the absence of adjacent teeth (P = 0.01), Eichner's classifications of B and C (P < 0.01), and Miyachi's occlusal triangles II, III, and IV (P = 0.03) were significantly associated with worse retention. Cox proportional hazards analysis identified the absence of adjacent teeth (HR = 1.78; 95% CI: 1.05-3.08; P = 0.03) and Eichner's classification B or C (HR = 2.27; 95% CI: 1.14-4.62; P = 0.02) as significant risk factors for the loss of root-fracture-treated teeth.

Root fracture repair may represent an effective strategy to delay tooth extraction and prevent occlusal collapse. Favorable retention outcomes were observed in patients with stable occlusal support, particularly those with adjacent teeth and an Eichner's classification of A.