Strengthening effect of bioceramic cement when used to repair simulated internal resorption cavities in endodontically treated teeth

Background. The reinforcement of teeth with internal root resorption is essential to prevent their fracture. Objectives. The aim of this study was to assess the fracture resistance of the premolar teeth with internal root resorption cavities (IRCs), repaired with glass-ionomer cement (GIC), gutta-percha (GP) or EndoSequence (R) Root Repair Material (TM) (RRM). Material and methods. Forty lower premolars, instrumented to size 50, were used. Ten teeth were assigned to the control group, which received the full obturation of the root canals. In the remaining 30, IRCs were prepared with Gates-Glidden burs. The apical 8 mm was obturated to the level of IRC using the single-cone technique. Then, the teeth were divided into 3 groups according to the material used for repairing the cavities (n = 10): GIC; GP; and RRM. The canals were filled with respective materials and backfilled with GP. All of the specimens were scanned at the level of IRC with a micro-computed tomography (micro-CT) system, and the volume of the IRCs and the percentages of voids in the filling materials were measured. The specimens were subjected to fracture testing. The force recorded at the time of fracture was analyzed with the Kruskal-Wallis test and the independent t-test. Results. The control group showed a significantly higher mean value of fracture resistance as compared to the groups with IRCs (p < 0.05). No significant difference was found between GIC and RRM, whereas the GP group had a significantly lower fracture resistance than other tested IRC groups (p < 0.05). The percentage of voids was significantly higher in the GIC group as compared to the GP and RRM groups (p < 0.05). Conclusions. EndoSequence Root Repair Material provides more strength to the teeth than the GP/sealer technique when both are used to fill a resorption cavity. The fracture resistance of the teeth filled with RRM was close to that obtained with GIC.