Objective: Evaluation of the shear bond strength of self-adhering flowable composite-resin to different surfaces of deciduous molars.
Methods: Eighteen-freshly extracted sound human deciduous molars were used. The teeth were embedded in acrylic blocks, such that their buccal surfaces were shown and aligned with the acrylic surfaces. The teeth were randomly divided into three groups. Group I: enamel surfaces without any intervention (Uncut Enamel), Group II: enamel surfaces with minimal grinding (Cut Enamel) and Group III: dentin surfaces. For all groups, self-adhering flowable composite-resin (DyadTM-flow, Kerr, USA); was applied. Specially designed holed-split Teflon mould was used for constructing composite - resin cylinders (3×3mm) over the buccal surfaces of the mounted teeth. The DyadTM-flow was applied in a central hole of the mould upon tooth surface, and then light cured for 20 seconds. The teeth were stored in distilled water at 37OC for 24 hours. The strength was recorded blindly by a different assessor using universal testing machine and statistically analyzed. Modes of failure were studied using digital microscope.
Results: Mean values of shear bond strength for groups I, II, III were 9.6, 5 and 3.6 MPa respectively, with statistically insignificant difference P=0.09 (P value≥0.05). Some specimens showed spontaneous de-bonding after water storage [group I (33.3%) and III (83.33%)]. Failure mode was 100% adhesive failure in all groups.
Conclusions: Bonding of DyadTM-flow was highest in uncut enamel however further material improvement may be required.