Effect of Different Surface Treatments on Repair Micro-Shear Bond Strength of An Injectable Composite

Objective
This study was conducted to evaluate the effect of three different surface treatments on the repairability of injectable composite of different age.
Materials and Methods
A total of 48 specimens were used in this study. Specimens were divided into two groups according to age of injectable universal composite; immediate and 3-month, water-aged. Each group was divided into three subgroups according to the different surface treatments to which the composite was exposed (n=8); etching (E), stone roughening followed by etching (S), and air abrasion followed by etching (A). Bonding agent (G Premio Bond) was applied, followed by same composite. Micro-cylindrical specimens were subjected to micro-shear bond strength testing, using a Universal Testing Machine, at a crosshead speed of 0.5mm/min. Fractured specimens’ mode of failure was observed and designated as adhesive, cohesive, or mixed. Data was statistically analyzed using two-way ANOVA followed by Tukey’s post hoc test.
Results
Two-way ANOVA test results showed that only surface treatment had a significant effect on bond strength (p<0.001), while aging and interaction were not significant (p>0.05). Post hoc pairwise comparisons showed surface treatments (E) and (S) have significantly higher micro-shear bond strength values than air abrasion (A) (p<0.05). Most dominant failure mode observed was mixed.
Conclusions
1. Repair behavior of injectable composite; immediate and water-aged for 3 months seems to be consistent.
2. Etching and stone roughening followed by etching, as surface treatments, performed well combined with universal adhesive for repair of injectable composite of both ages, while air abrasion seems to be non-advisable.