IMPACT OF INTEGRATING CRACK BRIDGING PHENOMENON ON THE FRACTURE RESISTANCE AND FRACTURE MODE OF THREE DIFFERENT ENDOCROWN RESTORATIONS IN ENDODONTICALLY TREATED POSTERIOR TEETH AN IN-VITRO STUDY

Aim of study: Compare three endocrown restorations using crack bridging material beneath them on the fracture resistance and fracture mode in endodontically treated posterior teeth. Material and methods: Fifty mature mandibular molars were selected. The samples were divided to five equal groups(n=10). Group (CN) 10 samples were kept untreated, Group (CP) 10 samples were endodontically treated only, the three test groups were subjected to root canal treatment and a standard butt joint endocrown preparation was done followed by application of 2mm Ever-X flow flowable composite to cover the floor of the pulp chamber. Group (EEC) 10 samples restored with Ever- X posterior composite endocrown, Group (EIM) 10 samples restored with IPS E-max CAD endocrown and Group (ECS) 10 samples restored with Cerasmart CAD/CAM endocrown. Following thermocycling fracture resistance and mode were assessed. Results: The experimental groups (EEC, EIM, and ECS) showed comparable fracture resistance values of 1085.3±99.5, 1126.3±92.9, and 1111.4±90.8 respectively. There were no significant differences between the experimental groups (EEC vs EIM p=0.376, EEC vs ECS p=0.571, EIM vs ECS p=0.747), suggesting similar performance among these treatments. Type III fractures were most prevalent in all groups. Type IV fractures were less common, with EIM showing the highest occurrence (20%). While there are some variations in fracture modes between groups, these differences are not statistically significant. Conclusion: Placing short fiber reinforced composite base beneath endocrown restorations not only produced near to intact tooth fracture resistance values but also yielded favorable modes of fracture.