The present study found a high prevalence and incidence of AP in association with root-filled teeth. The technical quality of many root canal treatments was unacceptable.

Both endodontists and GDPs were found to be observing national guidelines when performing root canal treatment. Greater use of apex locators was found amongst endodontists who tended to use a combined approach of an apex locator and periapical radiography.

The results of this study are in agreement with National and European guidelines, which recommend the use of a viewing box, magnification and masking for radiographic interpretation.

Both Endodontists and GDPs demonstrated compliance with guidelines relating to radiation protection being more significant amongst those clinicians working within specialist clinical practice.

The aim of this study was to evaluate the optimal horizontal beam angulation for the detection of second mesiobuccal canal (MB2) in maxillary first molar using three imaging modalities in terms of receiver operating characteristic (ROC) curve. Micro-computed tomography (micro-CT) was used to validate the presence or absence of MB2 canal. Images were generated with three different imaging modalities (analogue film, Visualix and VistaScan) for the twelve models at 10° intervals between 0° to 30° from both right and left sides. Each model consisted of maxillary second premolar, maxillary first and second molar arranged to replicate a posterior dentate maxilla. Images were scored on a 5-point scale by 15 observers. ROC analysis was performed to identify the optimal horizontal angulation for the three imaging modalities and the best observer groups. ANOVA was also used to assess if there was a difference between the three imagining modalities and between the observer groups. ROC analysis demonstrated that the highest area under the curve (AUC) was related to angle +20° (right). The AUC for the three radiographic techniques at angle +20° were as followed (analogue film, 0.625; Visualix, 0.544; VistaScan, 0.508). There was a significant difference between the analogue film and the other two digital systems (p<0.05). The +20° horizontal beam angulation for the analogue film was found to be optimal in the identification of MB2 canal with all imaging modalities. Endodontists demonstrated a significantly better performance compared with the other two groups.