Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Permanent Mandibular Molars: An In-vitro Study

Abstract

Introduction: Minimal invasive endodontics in the form of conservative access designs and minimal root canal taper preparation have been devised to preserve tooth structure and increase fracture resistance. Aim: To assess the influence of two different access cavity designs and two different final preparation tapers on fracture resistance of mandibular molars. Materials and Methods: In this in-vitro study, performed over a period of two months, a total of 54 extracted human permanent mandibular first and second molar teeth with completely formed apices were selected and for infection control, the teeth were stored in 10% buffered formalin solution for two weeks before the experiment. The teeth were then randomly allocated into three groups, Group C where no tooth preparation was carried out, Group TAC in which traditional access cavity design was performed and Group TREC where Truss access cavity was performed. The groups TAC and TREC were further subdivided into subgroup A and B with two different tapers 0.04 and 0.06 taper preparations. Mesial canals of the teeth were chosen for testing the minimal root canal taper preparations. After apical gauging the distal canals, obturation and postendodontic restoration was carried out in all teeth of both the test groups. The teeth in all three groups were subjected to fracture testing in a universal testing machine. The data were recorded. Oneway Analysis of Variance (ANOVA) and Tukey Post-hoc test were used for statistical analysis. Results: The fracture resistance between group C and groups TAC and TREC and their subgroups were found to be statistically significant (p<0.05). However, there was no statistically significant difference (p>0.05) observed between the two test groups TAC and TREC and their subgroups. Conclusion: The conservative truss access design in combination with a reduced root canal taper preparation has shown to have produced better fracture resistance values in comparison to other groups and their subgroups although the results were not statistically significant.