A comparison of the quality of root canal treatment in two Danish subpopulations examined 1974-75 and 1997-98

Aim The aim of this study was to compare the quality of root canal treatment in two Danish subpopulations. Methodology Group 1 (358 patients) was examined 1974-75 and group 2 (244 patients) 1997-98. All patients were more than 20 years old. All had undergone a full-mouth radiographic survey. In root-filled teeth the following parameters were assessed: the quality of the coronal restoration or crown, the lateral seal of the root filling, the length of the root filling, and the periapical status. Chi-squared tests were used for the evaluation of differences between the groups. Results In group 1 there were 975 endodontically treated teeth. in group 2 there were 753. In group I the majority of root-filled teeth were premolars, in group 2 the majority were molars (P < 0.001). The quality of coronal restorations (P = 0.35) and crowns (P = 0.68) did not differ significantly between the groups. In group 2 more teeth had adequately scaled root canals (P < 0.001) and adequate length of root filling (P < 0.001). More root-filled molar teeth had apical periodontitis (AP) than root-filled premolar and anterior teeth (P < 0.001). Conclusions Whilst the technical quality of endodontic treatment had improved during the last 24 years, basic differences between the populations prevented assessment of the impact of this change on disease frequencies. The study indicates that great care should be taken when comparing different patient populations, in particular more emphasis should be placed on the selection and description of study groups.