Influence of Contracted Endodontic Access on Root Canal Geometry: An In Vitro Study.

INTRODUCTION: Contracted endodontic cavities (CECs) have developed from the concept of minimally invasive dentistry and provide an alternative to traditional endodontic cavities (TECs). They have been designed in an effort to preserve the mechanical stability of teeth. The contracted cavity design preserves more of the dentin but may influence the geometric shaping parameters. The aim of this micro-computed tomographic study was to evaluate the influence of contracted endodontic cavities on the preservation of the original root canal anatomy after shaping with nickel-titanium rotary instruments.

METHODS: Thirty extracted human mandibular molars with fully formed apices and independent mesial canals were randomly assigned to group 1 (TEC) and group 2 (CEC). Each group was shaped using ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer). Irrigation was performed with 10% EDTA and 5% sodium hypochlorite. Samples were scanned before and after canal shaping to match canal volumes (SkyScan; Bruker microCT, Kontich, Belgium [100 kV, 100 μA, and 15-μm resolution]), and images were analyzed to evaluate canal volumes, surface areas, and centroid shift on cross sections at -1 mm and -3 mm from the apex.

RESULTS: TECs showed a greater preservation of the original root canal anatomy with less apical transportation than CECs, possibly because of the absence of coronal interferences and, therefore, fewer pecking motions required to complete instrumentation.

CONCLUSIONS: Within the limitations of this study, TECs may lead to a better preservation of the original canal anatomy during shaping compared with CECs, particularly at the apical level.