Journal of Dental Biomaterials
Volume:1 Issue: 1, 2014

Statement of problem: The effect of mouth washes on discolouration of dentalceramics with different surface preparations is not well documented. This in-vitro study has been conducted to evaluate the effect ofchlorhexidine (CHX) mouth rinse on colour stability of overglazed (OP), autoglazed,(AP) or polished porcelain (POP) specimens. The restorative material investigated in this study wasoverglazed, autoglazed, or polished feldspathic porcelain. A total of 48 cylandricalspecimens were prepared, (n=16 per each group). After baseline colour measurements,for a period of14 days 8 specimens of each group were immersed in 15 ml of 0.2%chlorhexidine mouth rinse twice daily for 2 min. After each immersion, the specimenswere washed and stored in artificial saliva. Half of the specimens from each groupwere selected randomly as controls and stored in artificial saliva that was changeddaily. The colour change (ΔE) of the specimens was measured by a spectrophotometerdevice. Data were statistically analyzed using 2-Way ANOVA followed by Tukey test All the specimens displayed colour changes after immersion in chlorhexidinemouth rinse. POP specimens exhibited more colour change compared to AP and OPspecimens (P=0.001). AP and OP specimens showed relatively the same colour changewhich was not significant compared to the control groups (P=0.9). Auto-glazed and over-glazed porcelain can tolerate chlorhexidine mouthrinse better than polished porcelain. However the colour changes of the ceramic withthree different surface preparations were not perceivable clinically.

Statement of Problem: Resin composites are a common type of tooth coloured restorative materials. These materials are brittle and their major shortcomings aresensitivity to flaws and defects, low tensile strength, and susceptibility to catastrophic failure. The role of home bleaching agents on the fracture toughness of resin composites using four-point bending test is scanty. To compare the fracture toughness (KIc) of resin composites on a four point bending test and to assess the effect of distilled water and a home bleaching agent on the resistance of the materials to fracture. seventy-two bar-shaped specimens were prepared from three materials: Rok (SDI), Estelite (Tokuyama), and Vit-l-escence (Ultradent) and divided into three groups. Two groups were assigned as “control” and conditioned in distilled water at 37oC for 24 hours or 21 days, respectively. The specimens in the third group (treatment) were stored in distilled water for 21 days and bleached using Polanight(SDI) for 2 hours daily. For each material, a total of 24 disc-shaped specimens were prepared and after each time interval loaded in a four-point bending test using a universal testing machine with a crosshead speed of 0.5 mm/m. The maximum loadto specimen failure was recorded and the KIc was calculated. Statistical analysis using two-way ANOVA showed a significant relationship between materials and treatment (P<0.05). Tukey’s test showed that after 24 hours of immersion in distilled water, KIc was not significantly different between materials; Rok revealed the highest value followed by Estelite and Vit-l-escence. The bleaching agent significantly decreased the KIc values of Estelite and Rok while it did not affect that of Vita-l-escence. Immersion in distilled water for all resin composites caused a significant decrease in KIc. The fracture toughness of the resin composites was affected by the bleaching agent and 21day immersion in distilled water.

Statement of problem: Surface staining of resin composite by dietary factors may be modified by the placement of a low-viscosity surface sealant aimed at reducing surface voids and defects occurring after light-curing and polishing. The aim of this study was to investigate the staining effect of various drinks and temperatures on the surface sealant (Fortify Plus™) sealed on a nano-filledresin composite (Supreme XTE™) after artificial aging at different temperatures. Surface sealant was applied on one surface of forty resin composite discs (10×2 mm). Five discs each were immersed in test solutions of black cola, commercial dark grape juice, coffee and distilled water (negative control). Discs were either placed at 4°C (20 discs) or 37°C (20 discs) and the colour difference (ΔE) was calculated based on the colour coordinates at 0 (baseline), 7, 14 and 28 days of staining treatment. Two-factor with replication analysis was carried out with ANOVA. The results showed significant discolouration after 28 days immersion in coffee (P<0.001) and grape juice group (P<0.001). Surface sealant significantly affected colour changes in coffee and grape juice group (P=0.002). Higher temperatures in coffee and grape juice also significantly increased the effect of staining (P<0.001). Surface sealant was able to reduce discolouration in the grape juice group only. A lower temperature of 4°C caused less staining in coffee and grape juice groups as compared to the 37°C corresponding test groups. Prolonged immersion time significantly increased discolouration in coffee and grape juice groups.

Statement of problem: The effect of different mouth rinses on the surface characteristics of ceramic materials is not documented. The aim of this study was to determine the effect of three mouth rinses, containing either alcohol, hydrogen peroxide or fluoride, on micro hardness of two dental ceramics, (Duceram love, IPS e.max Ceram). Eighty cylindrical disks were prepared and divided into eight experimental groups (n=10 for each group) according to the ceramic material and storage solutions. The micro hardness of each sample in all groups was recorded prior to testing. For each ceramic, three groups were immersed in one of the three mouth rinses for a total of 24 and 96 hours. The fourth group was immersed in distilled water as the control. At the end the specimens were taken out, rinsed, dried and tested using micro hardness tester. The results of the two-way ANOVA indicated that there was no interaction between media, time and materials (P>0.05). Micro hardness of the ceramics was not adversely affected by immersion in the studied mouth rinses. The patients with porcelain restorations should be assured that using mouth rinses containing hydrogen peroxide, alcohol or fluoride do not damage the surface hardness of the porcelain.

Statement of problem: Dental plaque is the main source for dental caries and there is no proper vaccine that can affect dental plaques. Daily use of an efficient anti-plaque product can be very beneficialin plaque control and, thus, prevention of caries. This study aims to evaluate the antibacterial effects of four products of Chlorhexidine and Fluoride on two types of cariogenic bacteria. In this in vitro study, the antibacterial effect of Chlorhexidine and Fluoride (gel and solution) against Streptococci Sanguis and Sobrinus wasevaluated. Chlorhexidine gluconate 1% gel (Corosodyl, France), Chlorhexidinegluconate 2% solution (Consepsis, Ultradent, US), Sodium fluoride 0.2% solution (Oral-B, US) and Acidulated Phosphate Fluoride 1.23% gel (Denti-Care, Canada)were used. The disc diffusion method was used for testing bacterial sensitivity. The data were analyzed using paired t-test and Chi-square test. In comparison with the negative control, each of the four gels and solutions showed antibacterial effects but the effects were not statistically significant for fluoride solution (P=0.217). For S. Sobrinus, the mean diameter of inhibition zone around the discs coated with fluoride gel (F g), fluoride solution (F s), Chlorhexidine gel (CHX g) and Chlorhexidine solution (CHX s) were 19, 9, 21.5 and 27.5mm, respectively. For S. Sanguis, the mean diameter of inhibition zone around the discs coated with F g,F s, CHX g and CHX s were 17, 11, 17 and 25mm, respectively. CHX s had the most effect on both bacteria and F s had the least. CHX g and F g were less effective than CHX s, respectively. The results demonstrated that 2% CHX s and 1.23% F g can be effective on inhibition of the growth of some of cariogenic bacteria. Therefore, these agents can be used in the prevention of Early Childhood Caries.

Statement of Problem: The question about resistance of resin composites under rest in removable partial denture (RPD) is still unanswered. It is important to find the strongest material that withstands the applied stresses when used under RPD components. To evaluate and compare the fatigue behavior of amalgam and composite estorations used under the rest of the removable partial denture. Forty-five permanent human upper premolars were prepared with standard class II DO cavities and divided into 3 groups of specimens (n=15 for each group). Group I was filled with amalgam (Dispersalloy), group II and III were filled with resin composite (Flitek Z250 and Tetric ceram, respectively). The teeth were stored in distilled water for 14 days before testing. After thermocycling, the “staircase” approach was used to determine the flexural fatigue limits (FFL). The mean differences were evaluated using One-Way ANOVA and post hoc test. A strong significant differences of flexural fatigue strength have been found between amalgam and composite groups (P<0.001). There was no significant difference between two groups of resin composite (P=0.1). To achieve more flexural fatigue strength in the rest seats, the use of resin composite in comparison with amalgam is recommended.