Theobromine versus casein phospho-peptides/Amorphous calcium phosphate with fluoride as remineralizing agents: effect on resin-dentine bond strength, microhardness, and morphology of dentine.

BACKGROUND: This study aimed to assess the impact of theobromine and casein phospho-peptides/amorphous calcium phosphate with fluoride (CPP-ACPF) on the resin-dentine bond strength, microhardness, and dentine morphology. METHODS: A total of 18 sound human molars for micro-tensile bond strength (µTBS), 20 sound human premolars for microhardness, and 30 premolars for Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) were used. Based on the pre-treatment used, teeth were split into six groups; sound dentine, demineralized dentine, and demineralized dentine treated with theobromine (Sigma Aldrich) and MI paste plus (GC International, USA) for two-time intervals; 5 min and 1 month. The bonded teeth were sectioned to produce 1 mm2 resin-dentine sticks which were evaluated for µTBS using a universal testing device (Instron 3365, USA). The dentine microhardness was tested by using the Vickers microhardness tester (Nexus 4000 TM, Netherlands). The pre-treated dentine surface was examined using SEM/EDX (Neoscope JCM-6000 plus Joel benchtop SEM, Japan). µTBS results were analysed with two-way ANOVA. Microhardness and EDX results were analysed with two-way mixed model ANOVA. The significance level was set at (p ≤ 0.05). RESULTS: While both remineralizing materials at the two-time intervals demonstrated µTBS comparable to sound dentine (46.38 ± 12.18), the demineralized group demonstrated statistically the lowest µTBS (p < 0.001). Whether used for 5 min or 1 month, theobromine significantly increased the microhardness (50.18 ± 3.43) and (54.12 ± 2.66) respectively (p < 0.001), whereas MI paste only increased the hardness (51.12 ± 1.45) after 1 month (p < 0.001). CONCLUSIONS: The pre-treatment of demineralized dentine with theobromine for 5 min or 1 month could enhance its bond strength and microhardness while for MI paste plus, only 1-month application was efficient to ensure remineralization.

Antimicrobial properties, compressive strength and fluoride release capacity of essential oil-modified glass ionomer cements-an in vitro study.

OBJECTIVES: This study was designed to investigate the antimicrobial properties, compressive strength and fluoride release capacities of high-viscous glass ionomer cements (GICs) after incorporation of cinnamon and thyme essential oils. MATERIALS AND METHODS: Experimental-modified GICs were prepared by incorporation of thyme and cinnamon essential oils into the liquid phase of the cement at 5 and 10% v/v. Antimicrobial activity against selected microorganisms (Streptococcus mutans and Candida albicans) was done using direct contact test. Compressive strength of the four new formulations and control group was tested using a universal testing machine while fluoride ion release was measured by ion-selective electrode at 1, 7, 14 and 28 days. Data analysis and comparisons between groups were performed using factorial and one-way ANOVA and Tukey's tests. RESULTS: All newly formulated GICs exhibited significantly higher inhibitory effects against both Streptococcus mutans and Candida albicans growth when compared to conventional GIC (p < 0.05). Compressive strength of 5% cinnamon-modified GIC (MPa = 160.32 ± 6.66) showed no significant difference when compared with conventional GIC (MPa = 165.7 ± 5.769) (p value > 0.05). Cumulative fluoride-releasing pattern at days 7, 14, and 28 were 10% cinnamon-GIC > 5% thyme-GIC > 5% cinnamon-GIC > 10% thyme GIC > conventional GIC. CONCLUSIONS: Incorporation of 5% cinnamon oil into glass ionomer resulted in better antimicrobial effects against S. mutans and C. albicans and increased fluoride-release capacity without jeopardizing its compressive strength. CLINICAL RELEVANCE: The 5% cinnamon-modified GIC appears to be a promising alternative restorative material in ART technique.

Effect of dentin biomodification using natural collagen cross-linkers on the durability of the resin-dentin bond and demineralized dentin stiffness.

OBJECTIVE: The purpose of this study was to evaluate the effect of using natural cross-linkers as sumac and curcumin on the durability of the resin-dentin bond and stiffness of demineralized dentin matrix. METHODS: Thirty sound molars were divided into 5 groups: Control (CO), Grape Seed extract (GSE), Cacao seed extract (CSE), Sumac extract (SE) and Curcumin extract (CE). The teeth had their coronal dentin exposed, etched, and pre-treated for 1 min with the extracts. Teeth were then bonded using Single-Bond II adhesive and 4 mm composite was built up on dentin surface. Teeth were sectioned into 1 × 1 × 8mm beams and their micro-tensile bond strength (µTBS) was tested after 24 h and 6 months of water storage. For stiffness testing, 15 teeth were sectioned to obtain dentin beams (1 × 1 × 6.5 mm), the beams were demineralized in 10% phosphoric acid then rinsed and divided into 5 groups. Beams were then immersed in their respective extract solution for 1 min after which they were subjected to a 3- point loading test using a universal testing machine to calculate their modulus of elasticity. RESULTS: After 24 h, no significant difference in µTBS was shown between all groups. After 6 Months, GSE, CE, and SE showed significantly higher µTBS compared to CO (p ≥ 0.05). For the modulus of elasticity; only GSE showed a significantly higher modulus compared to other groups. CLINICAL RELEVANCE: The application of grape seed extract, curcumin and sumac extract as dentin pre-treatments appear to be a promising approach to enhance the durability of the resin-dentin bond in a clinically relevant application time.

Evaluation of Two Resin Composites Having Different Matrix Compositions.

This study compared two resin composites with similar filler systems and different matrix compositions. The depth of cure (DoC), polymerization shrinkage, and marginal leakage were evaluated. A Filtek Bulk Fill resin composite (FB) and a Filtek Supreme resin composite (FS) were used. For the DoC and polymerization shrinkage, cylindrical specimens with different thicknesses were prepared. The DoC was attributed to the bottom/top ratios of Vickers microhardness numbers. For polymerization shrinkage, each specimen was firstly scanned using micro-computed tomography (µCT) then cured for 20 s, then for 10 s, and then for 10 s, and they were rescanned between each curing time. Data were processed using the Mimics software. For marginal leakage, standardized 5 mm cavities were prepared in 90 molars. After etching and bonding, materials were packed according to groups: FB-bulk, FB-incremental, and FS-incremental, which were cured for 20, 30, and 40 s, respectively. After thermo-cycling, teeth were stored in 1% methylene blue dye for 24 h and then sectioned and observed for dye penetration. The results showed insignificant differences in the shrinkage and leakage between the different packing techniques and curing times of both materials. In conclusion, the introduction of a novel matrix into resin composite composition enabled bulk-filling in one layer up to 5 mm deep while keeping a tolerable polymerization shrinkage.