Influence of Different Bonding Agents and Composite Resins on Fracture Resistance of Reattached Incisal Tooth Fragment

Statement of Problem: Reattachment of the fractured tooth fragment should be considered as a conservative treatment and valid alternative to a composite restoration. Purpose: This in vitro study was to evaluate the influence of different adhesives and composite resins on fracture resistance of dental fragment reattached to the sectioned incisal edges. Materials and Method: 120 sound human maxillary central incisors were selected under standard conditions and randomly divided into 3 groups, 12 sound teeth were used as a control group and the remaining teeth were assigned to 3 groups (n=36) and each group into three subgroups (n=12). The incisal third of the samples was sectioned using a diamond disk and the respective fragments were then reattached utilizing different intermediate restorative materials, namely: i) adhesive materials alone (OptiBond S or OptiBond XTR or OptiBond All-in-One; ii) Premise flowable composite and iii) Point 4 composite in the one of the mentioned adhesive interface. After storage for two weeks at 37°C and 100% humidity and then thermocycling; shear bond strength (SBS) was recorded in kilogram force (kgf) by applying a load in the middle incisal third with a Zwick Universal Testing Machine at a cross-head speed of 1 mm/min. Data was analyzed with one-way ANOVA and Tukey HSD (p< 0.05). Results: The control group had a significantly higher SBS than other groups (p= 0.001); the highest SBS values were obtained using the Premise flowable composite and OptiBond S adhesive (112.44±30.46 MPa); and the lowest with OptiBond All-in-One alone (33.97± 15.63 MPa). Conclusion: Although, none of the tested materials provided fracture resistance similar to that found with the intact maxillary central incisors; utilizing the Premise flowable composite and OptiBond S adhesive improved the SBS of the reattached fragment than other materials.