Healing and long-term prognosis of root-fractured permanent teeth: a retrospective longitudinal study

Aim The purpose of the present study was to evaluate permanent teeth with post-traumatic transversal root fractures, for their initial healing modality, the effect of candidate predictors and their long-term prognosis. Methodology A retrospective longitudinal clinical study was conducted to evaluate records from patients bearing transversal root fractures in permanent teeth in order to radiographically assess short-term healing and non-healing events in the fracture line, their prognostic factors and their relationship with long term outcomes. The inter-fragmentary tissues were classified as healing: hard tissue (HT), connective tissue (CT) or connective tissue and bone (CT + B) and non-healing: interposition of granulation tissue (GT). A competing risk survival analysis was conducted to estimate the hazards of healing and non-healing events in the short-term and the effect of demographic, clinical, and treatment variables was assessed using the subdistribution regression model (Fine & Gray). Results Radiographic findings showed 61.4% of healing in the short-term being strongly influenced by the presence and type of concomitant injuries to the coronal fragment. Teeth with concomitant crown fractures (sHR 24.38, 95% CI [3.16–188.3], p = 0.0022), luxations with dislocations (sHR 10.58, 95% CI [1.37–81.9], p = 0.0240) and subluxations (HR 9.66, 95% CI [1.14–81.7], p = 0.0370) were more likely to present non-healing of root fractures in the short-term. The healing rate in the long-term was of 75.9%, most of them with interposition of bone and connective tissue. Kappa statistics demonstrated an overall agreement of 67.1% between short and long-term healing patterns, in special HT and CT + Bone modalities. Conclusion Healing at the fracture site was the most frequent outcome, both in the short-term and in the long-term. Short-term healing modality was strongly influenced by the presence and type of concomitant injuries to the crown fragment, being the worst prognosis observed in root-fractured teeth with concomitant crown fractures, followed by concomitant luxations with dislocation. Clinical relevance Post-traumatic transversal root fractures have a positive prognosis supporting therefore, a more conservative approach for these teeth before considering more radical treatments.