Evaluation of remaining dentin thickness in molars following different access cavity designs and biomechanical preparation – An in vitro study

Aim: The objective of this study was to evaluate the impact of two different access cavity designs and biomechanical preparation on the remaining dentinal thickness (RDT) in mandibular molar teeth utilizing a 3-dimensional cone beam computed tomography (CBCT) imaging approach. Methods: A total of 60 fully formed mandibular first and second molars, with multiple roots, were carefully selected. Randomization of samples was divided into two groups, a conventional access preparation group (Group 1) and a conservative access preparation group (Group 2), each consisting of 30 teeth. The samples underwent a pre-CBCT scan at three specific regions: 2 mm above the cementoenamel junction (CEJ), at the CEJ, and 2 mm below the CEJ. This was done to quantify the overall thickness of dentin. For the control group, samples were obtained, and biomechanical preparation was performed using the ProTaper X2 file. Group 2 utilized CK microendodontic burs and a dental operating microscope (DOM) to access samples. Biomechanical preparation was performed using the TruNatomy Prime file. After the cleaning and shaping process, samples from both groups underwent a post-CBCT scan to measure the RDT. Results: The average RDT was lower in Group 1 compared to Group 2. Group 2 had greater preservation of pericervical dentin (PCD). The statistical difference between the experimental groups was extremely significant ( P < 0.001). Conclusion: This study demonstrates that conservative access using a DOM and TruNatomy files preserves more PCD than conventional access with ProTaper Next. CBCT analysis confirmed reduced dentin loss, supporting the advantages of minimally invasive techniques.