To compare the technical quality and long‐term outcomes of root canal treatment by general practitioners of a Swedish Public Dental Service, before and after an endodontic education including Ni–Ti rotary technique (NiTiR).

A random sample was compiled, comprising one root filled tooth from each of 830 patients, treated by 69 general practitioners participating in the education: 414 teeth root filled in 2002, pre‐education, using primarily stainless steel instrumentation and filling by lateral compaction, and 416 teeth root filled post‐education (2005), using mainly NiTiR and single‐cone obturation. Follow‐up radiographs taken in 2009 were evaluated alongside immediate post‐filling radiographs from 2002 to 2005. The density and length of the root fillings were registered. Periapical status was assessed by the Periapical Index (PAI), using two definitions of disease: apical periodontitis (AP) (PAI 3�+�4�+�5) and definite AP (PAI 4�+�5). Tooth survival was registered. Root fillings pre‐ and post‐education were compared using chi‐square and Fisher's exact tests. Crude extraction rates per 100�years were calculated for comparison of tooth survival. Explanatory variables (type of tooth, root filling quality, periapical status, marginal bone loss, type and quality of coronal restoration) in relation to the dependent variable (AP at follow‐up) were analysed by multivariable logistic regression.

Follow‐up data were available for 229 (55%) of teeth treated pre‐ and 288 (69%) treated post‐education: both tooth survival (P�<�0.001) and root filling quality were significantly higher (P�< 0.001) in the latter. However, there was no corresponding improvement in periapical status. Both pre‐ and post‐education, root fillings with definite AP on completion of treatment had significantly higher odds of AP or definite AP at follow‐up. For teeth treated post‐education, inadequate root filling quality was significantly associated with AP at follow‐up.

Despite a higher tooth survival rate and a significant improvement in technical quality of root fillings after the education, there was no corresponding improvement in periapical status.