Background: The reported risk of pulp necrosis (PN) is generally low in teeth with subluxation injuries. A concomitant crown fracture may increase the risk of PN in such teeth.
Aim: To analyze the influence of a concomitant infraction, enamel-, enamel-dentin-, or enamel-dentin-pulp fracture on the risk of PN in permanent teeth with subluxation injury.
Material and methods: The study included 404 permanent incisors with subluxation injury from 289 patients (188 males, 101 females). Furthermore, 137 teeth had suffered a concomitant crown fracture. All the teeth were examined and treated according to a standardized protocol.
Statistical analysis: The risk of PN was analyzed separately for teeth with immature and mature root development by the Kaplan-Meier method, the log-rank test and Cox regression analysis. The level of significance was set at 5%. Risk factors included in the analysis were: gender, patient age, crown fracture type, mobility, and reaction to electric pulp test (EPT) at the time of injury.
Results: Teeth with immature root development: The risk of PN was increased in teeth with a concomitant enamel fracture (log-rank test: p=0.002), enamel-dentin fracture (log-rank test: p<0.0001), enamel-dentin-pulp fracture (log-rank test: p<0.0001) and negative EPT at the time of injury (hazard ratio: 21, (95% CI: 2.5-172.5), p=0.005). Teeth with mature root development: The risk of PN was increased in teeth with an enamel-dentin fracture (hazard ratio: 12.2 (95% CI: 5.0-29.8), p<0.0001) infraction (hazard ratio: 5.1 (95% CI: 1.2-21.4) p=0.04), and negative EPT at the time of injury (hazard ratio: 8 (95% CI: 3.3-19.5), p<0.0001).
Conclusion: A concomitant crown fracture and a negative EPT at time of injury may be used to identify teeth at increased risk of PN following subluxation injury.