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The authors conducted a study to determine the validity of two commercially available in-office dental unit waterline test kits compared to the gold standard, R2A agar. Samples were collected from the air/water syringes of dental units and cultured on HPC Samplers, Petrifilm AC Plates, and R2A agar plates. HPC Samplers and R2A agar plates were incubated for 7 days and counted manually using magnification. Petrifilm AC Plates were counted after incubation time of 5 and 7 days using an electronic-plate reader. Validity measurements were calculated using a cutoff value < or = 500 colony-forming units per milliliter. The accuracy for the HPC Sampler compared to R2A agar was 71%. The accuracy for the Petrifilm AC Plates at 5 and 7 days was 79% and 87% compared to R2A agar. The Petrifilm AC Plate (7-day incubation) demonstrated higher sensitivity, specificity, predictive values, and accuracy than the HPC Sampler kit. [ABSTRACT FROM AUTHOR]

This study sought to determine how irradiance at various distances affected the hardness of a new silorane-based composite compared to a methacrylate-based composite resin restorative material. A visible-light curing unit was used at low and high irradiances. Plastic molds of various thicknesses (1, 2, 3, and 4 mm) were filled with composite resin and polymerized for 20 seconds at various distances (0, 2, 4, and 6 mm). After 24 hours of storage at 37°C, the microhardness of each specimen was tested at the bottom surface using a microhardness tester. These microhardness values were expressed as a percentage of maximum microhardness and analyzed with ANOVA and Tukey's post-hoc tests. At both low and high irradiances, the silorane-based composite (shade A2) was capable of acceptable (80%) bottom-to-maximum microhardness ratios at increments up to 3 mm and at curing distances up to 4 mm (at low irradiance) and 6 mm (at high irradiance). [ABSTRACT FROM AUTHOR]

Manufacturers often recommend refrigerated storage of self-etching enamel and dentin adhesives. The purpose of this study was to compare the shear-bond strength of composite resin to dentin using two different self-etching adhesives after extended storage at room or refrigerated temperatures. One- and two-step self-etching bonding agents were stored separately at room (23 degrees C) or refrigerated temperatures (5 degrees C) per manufacturer recommendations for 1, 4, or 18 months before testing. After each time period, composite resin was bonded to the dentinal surface of extracted human third molars using a mold and tested in shear on a universal-testing machine. Data were analyzed with analysis of variance/Tukey's test. No significant difference in bond strengths was found on the basis of storage temperature for either adhesive type. The one-step adhesive had a significant loss in bond strength over the 18 months of storage. However, the two-step self-etch adhesive had no loss in bond strength, regardless of storage temperature. [ABSTRACT FROM AUTHOR]

Objective: The goal was to evaluate the effect of high-heat storage of three dental adhesive bonding agents on the bond strength of composite resin to dentin.Methods: Three different adhesive bonding agents were stored for 1 month at the manufacturers' recommended temperatures and simultaneously at high temperatures (43 degrees C). The adhesives and a composite resin restorative material were bonded to the dentinal surface of five sectioned, extracted, human teeth for each of the six groups. The teeth were further sectioned into four beams per tooth (N=20) and separated with a universal testing machine. Data were analyzed with analysis of variance/Tukey's test and Student's t test.Results: One of the three bonding agents had significantly lower bond strength when stored in a high-heat environment (p = 0.0003).Conclusions: High-heat storage conditions, as may occur in areas of deployment in Southwest Asia, may cause a reduction in the performance of some dental adhesives, potentially leading to premature failure of the restoration. [ABSTRACT FROM AUTHOR]

This study sought to determine how repeated applications of a refrigerant spray on various cotton carriers affected the change in pulpal temperature. A thermocouple was placed at the roof of the pulp chamber of a human maxillary canine and connected to a thermometer logging at one-second intervals while the root was immersed in a water bath at 37 degrees C. Four different carrier types were used: large cotton pellets, small cotton pellets, cotton-tip applicators, and cotton rolls. Each carrier was sprayed with 1,1,1,2-tetrafluoroethane and placed on the crown for five seconds. Pulpal temperature change was recorded after each five second application of the same carrier to the tooth until a total of six consecutive sprays and applications of the carrier were applied. Each carrier group consisted of 10 performances of the six sets of readings (n = 10). The difference between baseline and the low temperature reading was calculated to determine the temperature change (in degrees C) in the pulp chamber per application. When the refrigerant spray was used, the large cotton pellet carrier generally produced the largest decrease in pulpal temperature at each repeated application compared to the other types of carriers. However, the same large cotton pellet should not be sprayed with the refrigerant more than two times before it is replaced. [ABSTRACT FROM AUTHOR]