The impact of CBCT on outcomes associated with endodontic access cavity preparation: a controlled human analogue study using 3D printed first maxillary molars.

Objectives: To identify if supplemental preoperative CBCT imaging could improve outcomes related to endodontic access cavity preparation, using 3D-printed maxillary first molars (M1Ms) in a rigorously simulated, controlled human analogue study.

Methods: 18 operators with three experience-levels took part in two simulated clinical sessions, one with and one without the availability of CBCT imaging, in a randomised order and with an intervening 8-week washout period. Operators attempted location of all four root canals in each of three custom-made M1Ms (two non-complex and one complex mesiobuccal canal anatomy). Primary outcome was tooth volume removed. Secondary outcomes were linear cavity dimensions, canals located, and procedural time. Operator confidence and 'helpfulness' of available imaging were recorded. Statistical analysis of data included: paired t-tests, Fishers Exact test, linear mixed effect modelling and Mann-Whitney U test, with an alpha level of .05 for all.

Results: When supplemental preoperative CBCT was available, there were significant reductions in volume of the access cavity and procedural times, with significantly increased mesiobuccal-2 (MB2) canal location, but only for teeth with non-complex anatomies and for more experienced operators. Linear mixed-effect modelling identified image type and operator experience as significant predictors of tooth volume removed and procedural time. There was significantly lower confidence in canal location and perceived 'helpfulness" (all experience groups) when conventional imaging only was used compared with when CBCT was available.

Conclusions: Supplemental preoperative CBCT had several beneficial impacts on access cavity preparation, although this only applied to teeth with non-complex anatomy and for more experienced operators.