The effect of pre-curing waiting time of different bonding resins on micro-tensile bond strength to dentin

ObjectiveTo evaluate the effect of 30 s waiting time of different bonding resins on their micro-tensile bond strength (μTBS) to dentin.MethodThe occlusal enamel of freshly extracted human third molars was removed to expose the middle dentin. The specimens were randomly assigned into four groups namely, Group I, two-steps-total-etch bonding system (Adper Single Bond 2/Filtek Supreme XT, ASB2/FSXT), Group II, two-steps-self-etch bonding system (Silorane System Adhesive/Filtek Silorane, SSA/FS), Group III, two-steps-self-etch bonding system (Adper SE Plus/Filtek Supreme XT, ASEP/FSXT) and Group IV, one-step-self-etch bonding system (Adper Easy One/Filtek Supreme XT, AEO/FSXT). Each group was further divided into two sub-groups according to the application time of the bonding resin (following manufacturer recommendation and 30s more than manufacturer recommendation). The corresponding resin composite (shade A3) was applied in 4 increments of 0.5–1 mm thickness each to build resin composite stump of 3–4 mm height. Each increment was light polymerized for 20 s using LED at intensity 1000 mW/cm2. The specimens were stored in deionized water at 37 °C for 24 hrs. The specimens were cut into bars according to the non-trimming technique (n = 20/group) with surface area of 0.81 mm2. The μTBS of the bars was tested using a micro-tensile device on a Universal testing machine at a crosshead speed of 1 mm/min.ResultTwo-way ANOVA revealed a statistical significant difference in the two main effects, the types of bonding systems (P = 0.0024) and the application times of bonding resins (P = 0.0005). There was no statistical significant interaction between the two main effects (P = 0.9257). The methacrylate-based two-steps-total-etch bonding system and two-steps-self-etch bonding system showed significant higher values than that of the one-step-self-etch bonding system.Conclusioni. Thirty-seconds pre-curing waiting time for bonding resins has a role in achieving higher μTBS to dentin. ii. One-step-self-etching bonding system ranked as the lowest bonding system.