الفهرس 
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Abstract
This study was conducted to evaluate the SBS durability and nanoleakage of the different chemical surface treatments on resin cement to chair side indirect resin composite material.
For shear bond strength testing, 200 resin composite discs and 200 cylinders were randomly divided into 20 experimental groups (n = 10) according to the two experimental factors investigated in this study: Factor 1: The resin composite surface treatment, 10 groups and Factor 2: The storage time, 2 groups. Before bonding, the fitting surface of each resin composite specimen was treated with each chemical surface treatment as specified. Resin composite cylinders were bonded to the discs using a dual cure resin cement and light cured. Half of the bonded specimens were stored for 24 hours and the other half was stored for 1-year. SBS test was run at a crosshead speed of 0.5 mm/min. For nanoleakage testing, specimens were assigned into 20 groups (n = 2) as for SBS testing. Specimens were evaluated using SEM operated in the backscattered mode to detect dye penetration. For resin composite/resin cement/resin composite interface and surface topography, specimens were examined using SEM. Surface microhardness was evaluated using Vickers microhardness tester. Statistical analysis was performed using Two-Way ANOVA/ Turkey’s HSD post hoc test.
The results showed that Two-Way ANOVA revealed that surface treatment, storage time and their interactions showed a significant effect on shear bond strength (P<0.001). For 24 hours, only, the HP+S showed the highest significant SBS values among all tested groups. All groups were shown statistically significant DROP in SBS after 1-year storage period. Nanoleakage results showed tracer penetration at the resin composite resin cement interface was not observed in all of the tested groups except, specimens treated with HF acid/HF acid+S and stored for 1-year. SEM evaluation of adaptation of resin composite/resin cement interface reveled the intimate adaptation of all experimental groups. Surface topography demonstrated the ability of all the tested surface treatment, except the PP surface treatment, to alter resin composite surface when compared to the NT groups. Surface microhardness testing showed that HF acid significantly decreased surface microhardness compared to all tested groups. The PP group showed statistically significant DROP in surface microhardness when compared to the NT group.
Conclusions
Within the limitations of this study, the following conclusions could be suggested:
1- Although, the different surface treatments improved the SBS of resin cement to chair side resin composite used in this study compared to NT, the PP surface treatment solely or with silane did not revealed any positive effect on the SBS.
2- Storage in water for 1-year negatively affected the SBS durability regardless of the type of chemical treatment used.
3- The application of silane over the chemically treated resin composite surfaces did not improve the durability of the SBS. Its effect was dependent on the type of chemical treatment used.
4- The intimate adaptation of resin cement to resin composite was evident even after 1-year storage period, with no nanoleakage, except for the HF and HF+S groups stored for 1-year, which exhibited silver nitrate depositions along the interface after 1-year storage time.
5- The use of HF acid dramatically decreased the surface microhardness compared to all tested treatments.
6- Alteration of surface morphology was clear for all the chemical surface treatments used in this study compared to the NT group, except for the PP surface treatment, which showed no surface morphology alteration.
It seems that chemical surface treatments of chair side resin composite material used in this study can be adopted as effective, easy and non-costly alternative to more sophisticated treatments. The use of Potassium Permanganate to treat highly filled resin composite should be reconsidered in future studies.