Effect of different access cavity designs on fracture toughness of endodontically treated teeth: a systematic review...

Objective To compare the effect of different endodontic access cavities on fracture toughness of extracted endodontically treated human teeth.Data/sources An electronic literature search was performed in seven databases as well as hand search until September 2020. Risk-of-bias tool was used to evaluate the quality of included studies. Random effects frequentist network meta-analysis was performed, with mean difference (MD) and 95% confidence interval (CI) as the effect measure. Confidence in the documented evidence was assessed through the newly fuelled Confidence in Network Meta-analysis (CINeMA) framework based on the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.Study selection A total of 844 articles were obtained in the electronic and hand search. After the application of the eligibility criteria and duplicate removal, 14 studies were included in this systematic review. All included studies were in vitro that evaluated the influence of conservative endodontic cavities (CECs) on fracture toughness in extracted endodontically treated human teeth and compared to traditional endodontic cavities (TECs). In total, ten studies (n = 456) were included in the network meta-analysis for molars. The overall risk of bias was moderate.Results The results showed that when compared to intact teeth, the greatest reduction in fracture resistance was reported for TEC (MD: -927.52; 95% CI [-1304.80; -550.24]) and CEC showed least reduction in fracture resistance (MD: -365.59; 95% CI [-759.02; 27.83]). The surface under the cumulative ranking curve (SUCRA) value for intact teeth was highest (85.4% probability of being ranked as first), followed by CEC (51.4% probability of being ranked as second), with CEC presenting the highest probabilities to be the most effective access cavity design, according to the RANK (receptor activator of NF-kappaB) table. Level of confidence varied from low to moderate across all formulated comparisons.Conclusion Overall, based on the included in vitro studies in this systematic review, CEC was the most favourable access cavity design when compared to other (truss access cavities, TEC and ninja cavities) and TEC was the least favourable for fracture resistance; however, the level of evidence was moderate.