Erosive potential of different types of grape juices

The purpose of the present study was to evaluate the erosive potential of different types (concentrated and powdered) and commercial brands of industrialised grape juices. The pH of all five fruit drinks was measured at two time points: immediately after preparation and 24 hours later. Sixty specimens of bovine enamel were randomly allocated and immersed in different types of grape juice (n = 10) for 10 minutes four times a day for fifteen days. The enamel alteration was analysed using surface Knoop microhardness (KHN) and surface roughness (Ra) tests at baseline and on the 5th, 10th and 15th days of the experiment. Two way ANOVA, Tukey's post hoc and Pearson's correlation tests were used for statistical analysis (α = 5%). The grape juices presented pH values ranging from 2.9 to 3.5. All of the tested juices promoted significant enamel mineral loss (p < 0.05) on the first evaluation (5th day of immersion) and produced a significant increase in the mean roughness from the 10th day on when compared to the control group (p < 0.05). By the 15th day, all of the beverages had produced surface roughnesses that were significantly higher than that of the control group. The results suggest that all grape juices, regardless of their commercial presentation, present erosive potential

Eroded dentin does not jeopardize the bond strength of adhesive restorative materials

This in vitro study evaluated the bond strength of adhesive restorative materials to sound and eroded dentin. Thirty-six bovine incisors were embedded in acrylic resin and ground to obtain flat buccal dentin surfaces. Specimens were randomly allocated in 2 groups: sound dentin (immersion in artificial saliva) and eroded dentin (pH cycling model - 3× / cola drink for 7 days). Specimens were then reassigned according to restorative material: glass ionomer cement (KetacTM Molar Easy Mix), resin-modified glass ionomer cement (VitremerTM) or adhesive system with resin composite (Adper Single Bond 2 + Filtek Z250). Polyethylene tubes with an internal diameter of 0.76 mm were placed over the dentin and filled with the material. The microshear bond test was performed after 24 h of water storage at 37ºC. The failure mode was evaluated using a stereomicroscope (400×). Bond strength data were analyzed with two-way ANOVA and Tukey's post hoc tests (α = 0.05). Eroded dentin showed bond strength values similar to those for sound dentin for all materials. The adhesive system showed the highest bond strength values, regardless of the substrate (p < 0.0001). For all groups, the adhesive/mixed failure prevailed. In conclusion, adhesive materials may be used in eroded dentin without jeopardizing the bonding quality. It is preferable to use an etch-and-rinse adhesive system because it shows the highest bond strength values compared with the glass ionomer cements tested

Fluoride release and uptake of glass ionomer cements indicated for atraumatic restorative treatment/Liberação e reincorporação de fluoreto de cimentos de ionômero de vidro utilizados no tratamento restaurador atraumático

Objective: This study aimed to evaluate the fluoride release and uptake capability of high-viscous glass ionomer cements. Methods: Cylindrical specimens prepared with five different materials (n=3) - Vidrion R (control), Vidrion N, Chem Flex, Fuji IX and Ketac Molar ART - were maintained in individual containers with deionized water for 28 days. Every 24 hours, the water was changed, and after that, the specimens were immersed for 3 minutes in containers with 1100 ppm fluoridated dentifrice diluted in deionized water, before turning to new containers with deionized water. This procedure was repeated for 3 days, totalizing 31 days of experiment. The amount of fluoride ions was measured in the containers used during the experiment with specific electrode for ion detection coupled to a potentiometer. Data were submitted to analysis of variance and LSD test, (α=5%) Results: Vidrion R presented the highest level of fluoride release during the studied period and this difference was statistically significant for all days of experiment. Between the 28 th and 31 st days, the material which released the highest amount of fluoride was also Vidrion R and the one which released the smaller amount of fluoride was Ketac Molar ART. Vidrion N was not able to be recharged with fluoride from the fluoridated dentifrice. Conclusion: Glass ionomer cements suitable for use in ART seem to release fewer amounts of fluoride ions when compared to conventional (low strength) glass ionomer cement