The probability of and factors influencing tooth survival following non‐surgical root canal treatment – a prospective study

Abstract

Aim To investigate the probability of and factors influencing tooth survival following primary or secondary root canal treatment.Methodology This prospective study involved annual follow‐up of up to 4 years of primary (759 teeth, 572 patients) or secondary (858 teeth, 642 patients) root canal treatment in an Eastman cohort. Informed consent was obtained from the patients. Pre‐, intra‐ and post‐operative data were collected prospectively on customised proforma. Information about extraction of the root treated tooth was reported by the patient, the referring dentist or extracted from the patient's hospital medical records. The timing and reasons for extraction were recorded. Tooth survival was estimated and prognostic factors investigated using Cox regression. Clustering effects within patients were adjusted in all models using robust standard error.Results The 4‐year tooth survival after primary root canal treatment (95.4%) or secondary root canal treatment (95.3%) were similar. Fourteen prognostic factors were identified. Significant patient factors included: History of diabetes and systemic steroid therapy. Significant pre‐operative factors included: narrow periodontal probing depth; pain; discharging sinus; cervical root resorption; and iatrogenic perforation (for retreatment cases only). Significant intra‐operative factors included: iatrogenic perforation; patency at apical terminus; and extrusion of root fillings. Significant post‐operative restorative factors included: Presence of cast restoration or temporary restoration; presence of cast post & core; proximal contacts with both mesial and distal adjacent teeth; and terminal location of the tooth. The presence of pre‐operative pain had a profound effect on tooth loss within the first 22 months after treatment (HR = 3.1; P = 0.001) with a lesser effect beyond 22 months (HR = 2.4; P = 0.01). Patency at the apical terminus reduced tooth loss (HR = 0.3; P < 0.01) within the first 22 months after treatment but had no significant effect on tooth survival beyond 22 months. Extrusion of gutta‐percha root filling did not have any effect on tooth survival (HR = 1.1; P = 0.2) within the first 22 months but significantly increased the hazard of tooth loss beyond 22 months (HR = 3.0; P = 0.003).Conclusions The 4‐year tooth survival following primary or secondary root canal treatment was 95%; with fourteen prognostic factors common to both.