The effect of repair protocols and chewing simulation on the microtensile bond strength of two resin matrix ceramics to composite resin.

BACKGROUND: To assess the micro tensile bond strength (µTBS) of two resin matrix ceramic (RMC) blocks bonded to composite resin by using different repair protocols with and without chewing simulation (CS). MATERIALS AND METHODS: Two resin matrix ceramic blocks (Vita Enamic and Lava Ultimate) were divided into 4 groups according to the surface treatments: Bur grinding (control), Bur grinding + silane, 9.5% HF acid etching, and 9.5% HF acid etching + silane. The single bond universal adhesive was applied on all specimens after the surface treatments according to the manufacturer's instructions, it was administered actively on the treated surface for 20 s and then light cured for 10 s, followed by incremental packing of composite resin to the treated surface. Each group was further divided into 2 subgroups (with/without chewing simulation for 500,000 cycles). A micro tensile bond strength test was performed for each group (n = 15). The effect of surface treatments on the materials was examined by using a scanning electron microscope (SEM). The micro tensile bond strength (MPa) data were analyzed with a three-way ANOVA, the independent t-test, and one-way ANOVA followed by the Tukey post-hoc test. RESULTS: µTBS results were significantly higher for Lava Ultimate than Vita Enamic for all the surface treatment protocols with (p < 0.01). The chewing simulation significantly negatively affected the micro-tensile bond strength (p < 0.001). Bur grinding + saline exhibited the highest bond strength values for Lava Ultimate, both with and without chewing simulation. For Vita Enamic, bur grinding + saline and HF acid + saline showed significantly higher bond strength values compared to other surface treatments, both with and without chewing simulation (p ≤ 0.05). CONCLUSION: Bur grinding + silane could be recommended as a durable repair protocol for indirect resin matrix ceramics blocks with composite resin material.

Release characterization and biological effect of Glass Ionomer Functionalized with two different chlorohexidine derivatives: an in vitro study

ABSTRACT Objective: To evaluate the effect of adding two different chlorohexidine derivatives; chlorhexidine hexametaphosphate and chlorhexidine digluconate to glass ionomer at three different concentrations (0.25%, 0.75%and 1.5%) regarding the antibacterial effect, chlorhexidine release and fluoride release. Methods: A total of 405 specimens were prepared and tested after 7 days, 3 months and 6 months of storage in distilled water (n=5).For testing antibacterial effect, chlorhexidine release and fluoride release, the mix was packed in a ready-made Split Teflon molds to obtain disc-shaped specimen with dimensions 10 mm in diameter and 2 mm thickness according to ISO standardizations. One-way ANOVA and One-way repeated measure ANOVA test were used for statistical analysis of data. Results: The incorporation of chlorhexidine into ChemFil Superior glass ionomer cement in both derivatives has high significance ability to provide a long-term antimicrobial effect on Streptococcus mutans and Lactobacillius acidophilus. The chlorhexidine release was increased by adding chlorhexidine in both derivatives to GIC than the unmodified Glass-ionomer cement for study duration. However, the fluoride release was decreased in the modified specimens than the original one. Conclusion: Addition of chlorhexidine enhanced the antibacterial effect of the glass ionomer and chlorhexidine release. However, fluoride release was reduced than original