[Pulp prognosis and influencing factors of luxation injuries in young permanent teeth: a retrospective study]

Objective: To evaluate the pulp prognosis and related influencing factors of traumatic teeth with dislocating periodontal injuries, and to provide references for the clinical treatment of dislocating traumatic teeth. Methods: A retrospective study design was adopted. Clinical data of 245 patients (345 affected teeth) who visited the Department of General Dentistry & Emergency of the School of Stomatology of The Fourth Military Medical University from January 2021 to December 2023 were collected. All cases met the diagnostic criteria for dislocating injuries specified in the International Association of Dental Traumatology(IADT) guidelines for the management of traumatic dental injuries, with complete data and a follow-up period of≥6 months. Variables including patient gender, age, type of trauma, apical foramen closure status, stage of root development (Nolla stage), time to consultation after trauma and type of pulp tissue prognosis were recorded. SPSS 21.0 software was used for univariate chi-square tests, linear-by-linear Association test and multivariate Logistic regression analysis to identify factors associated with pulp tissue prognosis. Results: Among the 345 affected teeth, only 44.3%(153/345) achieved pulp survival. Univariate analysis showed that age, apical foramen closure status and type of injury had significant effects on pulp prognosis (all P<0.05). Linear-by-linear Association analysis showed that the pulp necrosis rate increased significantly with advancing Nolla stage (χ²=22.05, P<0.001). Multivariate logistic regression analysis showed that apical closure and injury type were independent risk factors for pulp prognosis. The pulp survival rate was highest in teeth with subluxation [67.2%(78/116)] and lowest in those with lateral luxation [28%(21/75)]. Additionally, teeth with open apical foramina had a higher survival rate[68.3%(56/82)] than those with closed apical foramina[36.9%(97/263)](χ²=24.99,P<0.001). Conclusions: Apical foramen closure status, type of injury and stage of root development are key influencing factors for the pulp prognosis of traumatic teeth with dislocating periodontal injuries. The risk of pulp necrosis increased with the degree of root development.Teeth with subluxation have the best pulp prognosis, while those with closed apical foramina, extrusive luxation, lateral luxation, or intrusive luxation are more prone to pulp necrosis. Clinically, targeted intervention and enhanced follow-up should be implemented for these high-risk cases.