Effect of different bonding techniques on marginal adaptation of Harmonize composite resin at different storage times.

Abstract Background This study evaluated the effect of different bonding techniques on marginal adaptation of Harmonize composite resin at different storage times. Methods Hundred twenty upper premolars were divided into two main groups (n = 60) according to the type of the adhesive system used (self-etch adhesive system or total etch adhesive system). Each group was further divided into three subgroups (20 teeth each) according to the storage times into one day, three months and six months. Standardized Class II cavities were prepared and restored with Harmonize composite incrementally. Teeth were stored in distilled water at room temperature. After each storage time, teeth were sectioned buccolingually into two halves and examined under digital stereomicroscope for the purpose of gap formation detection and scanning electron microscope examination was done to evaluate resin-dentin interfaces. The recorded values were tabulated and statistically analyzed. Regression model using three-way Analysis of Variance (ANOVA) was used for testing significance of the effect of adhesive system, storage period and their interactions on the mean gap area. Tukey’s post-hoc test was used for pair-wise comparisons between the groups when ANOVA test is significant. The significance level was set at P ≤ 0.05. Results Self-etch adhesive system showed statistically significant higher mean gap area than Total-etch adhesive system at the occlusal and cervical margins. Six months period showed the statistically significant highest mean gap area. There was no statistically significant difference between 1 day and 3 months periods; both showed the statistically significant lowest mean gap area values respectively at the occlusal and cervical margins. Conclusions Total-etch adhesive system enhances the marginal adaptation when compared to self-etch adhesive system and the storage period of composite resin in water has adverse effect on the marginal adaptation to all groups with time.