Impact of systemic diseases and tooth-based factors on outcome of root canal treatment

To investigate the impact of systemic health and tooth-based factors on the outcome of root canal treatment (RCT).

The target population consisted of all patients receiving RCT at the Helsinki University Clinic in 2008-2011. The inclusion criteria were diagnosable pre- and postoperative (minimum 6 months after root filling) radiographs and adequate patient records of RCT available. Teeth extracted for nonendodontic reasons were excluded. Patient documents including digital radiographs of 640 permanent teeth in 504 patients were scrutinized. The radiographs were assessed by two examiners under standardized conditions. The Periapical Index was used to define radiographically 'healthy' and 'healing' cases as successful. Data included systemic health, technical quality of root fillings, type of restoration and level of alveolar bone loss. Statistical evaluation of differences between groups included chi-squared tests and Fisher's exact tests. Logistic regression modelling utilizing robust standard errors to allow for clustering within patients was applied to analyse factors related to the outcome of RCT.

The mean age of patients was 51.5 years (standard deviation (SD) 15.0; range 10-83), and 49% were female. In 41 cases (6%), the patient had diabetes mellitus (DM), in 132 (21%) cardiovascular disease and in 284 (44%) no systemic disease. The follow-up period was 6-71 months (mean 22.7). In the primary analyses, the success rate of RCT was 73.2% in DM patients and 85.6% in patients with no systemic disease (P = 0.043); other systemic diseases had no impact on success. In the multifactorial analysis, the impact of DM became nonsignificant and RCTs were more likely to succeed in the absence of apical periodontitis (AP; odds ratio (OR) = 4.4; P < 0.001), in teeth with optimal root filling quality (OR = 2.5; P < 0.001), in teeth restored with indirect restorations (OR = 3.7; P = 0.002) and in teeth with none/mild alveolar bone loss (OR = 2.4; P = 0.003).

DM diminished the success of RCT, especially in teeth with apical periodontitis. However, tooth-based factors had a more profound impact on the outcome of RCT. This should be considered in clinical decision-making and in assessment of RCT prognosis.