PubMed · 10765821
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M W Davis. 1999. Dazzle camouflage.. https://pubmed.ncbi.nlm.nih.gov/10765821/
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OBJECTIVES: The aim of the study was to investigate the influence of two resin composites with different handling properties and application techniques on the homogeneity of a restoration placed in small and large cavities. Furthermore, the operator-effect on the restorative procedure was studied. METHODS: Standardized Class I cavities of two sizes were prepared in artificial lower first molars. The cavities were restored with two resin composites (Surefil and Ecusit) using either a packing or an injection technique. Six operators were involved in the study, five general practitioners and one final-year dental student. Each operator restored 40 preparations, ten in each group. After finishing, the restorations were sectioned and inspected for the presence of voids and porosities. RESULTS: 240 restorations were placed and 480 sections were available for evaluation. Only 143 sections were totally free of porosities. For both the small and large preparation design the Ecusit composite used with the injection technique resulted in significantly less porosities in the restoration. Differences between operators were evident, but none of the operators achieved significantly better results with the packing technique than with the injection technique. SIGNIFICANCE: The use of a syringable resin composite results in a better adaptation of the restoration compared to a packable resin composite.
Five visible light-cured composite resins used as restoration or adhesive materials in dentistry, were irradiated with high energy plasma light (1300 mW/cm2), and contraction, rate of contraction, irradiation-induced temperature were analysed. A comparison was carried out with the same materials irradiated with a conventional halogen light (400 mW/cm2). The exposure to the photoactivating lights was either continuously or sequentially in three or more intervals with 10 min between intervals. Comparing the lengths of exposure of both lights, which induced the same contraction in a given material, it was found that the exposure length to the plasma light was greatly reduced, when compared with the exposure length of the halogen light (1:10). Frequently, the final contraction of plasma-irradiated materials was lower, whereas the rate of contraction, as indicated by the linear dimensional variation curves obtained by laser beam scanning method, did not show significant differences between the two lights. The temperature increase induced by plasma light on the material did not exceed the temperature induced by conventional light.
OBJECTIVE: To determine the suitability of two mechanical test methods for the in vitro evaluation of dental bonding agents. METHODS: The first method was the Iosipescu shear test in which a pure shear stress is induced in a notched beam sample, and the second was a multilayer vibrating reed test in which the effectiveness of bonding could be assessed by the magnitude of relative elastic modulus and mechanical damping factors. The tests were applied to bonded samples of high-copper amalgam, gallium alloy and composite resin with two different types of adhesive. Representative data is presented to show the capabilities of the test methods. RESULTS: Both methods were shown to generate more consistent data with lower scatter than that usually reported in this field. Each may be used to provide information of clinical relevance. CONCLUSION: With further development, these test methods could make a useful contribution to the assessment of dental bonding agents.