Bahareh Asgartooran

Objectives: Dental caries, a prevalent infectious disease affecting teeth, ranks highest among 328 diseases, according to a 2017 Lancet study. In demineralized human dentin, matrix metalloproteinase‐3 (MMP3) functions as a proteoglycanase, contributing to the degradation of proteoglycan components. This process exposes collagen fibrils, thereby facilitating the demineralization of the dentin matrix. Inhibiting MMP3 shows potential for preventing dental caries.Methods: The binding affinity of 20 cinnamic acid derivatives, namely cynarin, chlorogenic acid, rosmarinic acid, cinnamyl caffeate, phenethyl caffeate, N‐p‐coumaroyltyramine, caffeic acid 3‐glucoside, caffeic acid phenethyl ester, roscovitine, benzyl caffeate, o‐coumaric acid, artepillin C, caffeic acid, methyl caffeate, 2‐methylcinnamic acid, ferulic acid, drupanin, p‐coumaric acid, cinnamic acid, and sinapinic acid, to the MMP3 catalytic cleft, was assessed utilizing AutoDock 4.0. Molecular dynamics simulation was then employed to analyze the stability of backbone atoms in free MMP3, MMP3‐positive control inhibitor, and MMP3 complexed with the top‐ranked cinnamic acid over a 100 ns computer simulation.Results: Four cinnamic acids demonstrated ΔG_binding scores below −10 kcal/mol, with cynarin emerging as the most potent MMP3 inhibitor, featuring a ΔG_binding score and inhibition constant value of −15.57 kcal/mol and 3.83 pM, respectively. The MMP3–cynarin complex exhibited stability after a 50 ns computer simulation, showing a root‐mean‐square deviation of 8 Å.Conclusions: The inhibition of MMP3 by cynarin, chlorogenic acid, rosmarinic acid, and cinnamyl caffeate holds promise as a potential preventive strategy for dental caries.

Background: Considering the therapeutic properties of the compounds used in Albodent Iranian toothpaste and little evidence about the effect of NovaMin toothpaste on primary caries lesions, the purpose of this research was to compare the effect of toothpaste containing fluoride and toothpaste containing bioactive glass with Albodent toothpaste on enamel remineralization in a laboratory manner. Methods: Overall, 24 healthy human premolar teeth were selected and divided into buccal and lingual halves. The demineralization cycle of the samples was performed for 14 days. The samples were classified into four groups and were brushed twice a day for 28 days with tested toothpaste. A microhardness test was conducted, and changes in the enamel surface and morphology of one sample selected from each group were evaluated by scanning electron microscopy. The analysis of variance and Tukey’s tests were used for the statistical analysis of the data. Results: The average difference in microhardness in the studied groups was statistically significant (P<0.05) when compared two-by-two with the control group. The most noticeable difference was found in the comparison of the Sensodyne group with the control group, while the lowest difference was observed in the comparison of the Albodent group with the control group. Conclusion: The presence of NovaMin in toothpaste along with fluoride can increase the efficiency of the remineralization rate of primary enamel lesions compared to fluoride toothpaste without bioactive glass. In addition, the effectiveness of herbal toothpastes, which do not contain essential artificial ingredients in the remineralization of primary enamel lesions was lower than that of non-herbal fluoride toothpastes.

Background: The methods of increasing the longevity of dental burs by improving the mechanical properties of these surfaces, can increase their longevity. This study assessed the effect of diamond-like carbon (DLC) coating applied by the physical vapor deposition (PVD) technique on wear of diamond and tungsten carbide (TC) burs. Methods: In this in vitro study, 30 diamond and 30 TC burs were evaluated in four groups, including TC burs without coating (control), TC burs with a 3.5-µm DLC coating applied by the PVD technique, diamond burs without coating (control), and diamond burs with a 3.5-µm DLC coating applied by the PVD technique. The burs were weighed by a digital scale, underwent the pin-on-disc wear test, and were weighed again. The weight loss indicated the degree of wear in each group. For qualitative assessments, the surface of the burs was inspected under a stereomicroscope at×4 and×10 magnifications before wear, halfway through the test, and after the test. Finally, the data were analyzed by two-way ANOVA (α=0.05). Results: The effect of DLC coating was significant on the wear of burs (P=0.032), but the effect of the type of bur and their interaction effect on wear were not significant (P=0.151). A significant difference existed in wear among the four groups (P < 0.001), and the wear of coated burs was significantly lower than that of non-coated burs (P=0.012). Stereomicroscopic assessments revealed some residual diamond particles, the impression of dislodged particles and the path of wear on the surface of diamond burs, and the path of wear on the surface of TC burs. Conclusions: Overall, the DLC coating of diamond and TC dental burs by the PVD technique could increase their wear resistance irrespective of the bur type.

Background: This study aimed to assess the effect of strontium-doped 45S5 bioglass (BG) and Nd:YAG laser on the microhardness of demineralized enamel. Materials and Methods: In this in vitro, experimental study, 65 sound enamel samples were prepared of human premolars and polished, and then immersed in a demineralizing solution for 10 weeks. The samples were randomly divided into 5 groups of control, BG, laser, laser plus BG, and BG plus laser. Two samples of each group underwent assessment of surface morphology under a scanning electron microscope. Finally, the microhardness of samples was measured using a Vickers hardness tester, and data were analyzed by ANOVA. Results: The mean microhardness of the BG group was significantly higher than that of other groups (P<0.05). The lowest microhardness was noted in the control group. The difference in microhardness was significant between laser and laser plus BG groups (P<0.05). Further, the BG plus laser group had a significant difference in microhardness with BG and control groups (P<0.05). The difference between laser plus BG and control groups was also significant in this respect (P<0.05). Eventually, maximum morphological changes were observed in the BG group. Conclusions: Overall, BG seems to be effective for the treatment of incipient enamel caries. It effectively increases enamel microhardness and decreases mineral loss while preserving the integrity of the enamel surface.

Background: Adhesion of composite resins to dentin is crucial in restorative dentistry. The aim of this study was to evaluate shear bond strength of composite restorations to dentin under different cycling conditions. Methods: Ninety extracted premolar teeth were randomly divided into 9 groups (n=10). The samples were mounted in resin and sectioned to prepare dentin samples. Then the samples were polished with 600-grit silicon carbide sanding sheet, and adhesive types of bonding (5th generation/Ambar, 6th generation/Clearfil SE bond, 8th generation/G-Premio) were applied on them. Afterward, composite resin was bonded to the surface, and cycling was exerted (control: no cycling; thermal cycling: 3000 cycles, 5°C to 55°C; thermal/erosive cycling: thermal cycling and storage in hydrochloric acid, pH = 2.1, 5 minutes, 6 times a day, for 8 days). Shear bond test was done for the specimens. Finally, statistical analysis was done using a two-way analysis of variance (ANOVA) and Tukey test (P < 0.001). Results: G-Premio displayed the most bond strength. No significant differences were observed between Clearfil liner bond and Ambar bond. While significant differences were observed in different cycling conditions. Measured bond strength was reduced by thermal/erosive cycling. Conclusions: Thermal cycling and thermal/erosive cycling could affect the shear bond strength of composite to dentin. Universal bonding systems can also increase the shear bond strength of composite resin to dentin.

Journal of North Khorasan University of Medical Sciences مجله دانشگاه علوم پزشکی خراسان شمالی