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Dentists and dental technicians are interested in new products. They should, together, evaluate the quality of such new products with regard to technical, economic and esthetic aspects.

Standards for dental materials are available for both biological and chemical/physical properties. In order to predict the clinical performance of a material by means of standard tests, both the test and the method used in the test should ideally simulate clinical usage. However, owing to lack of knowledge with regard to intra-oral failure modes, and technical considerations in the performance of tests, this ideal may not always be achieved.

Fracture toughness (KIC), critical stress intensity factor, and bending strength of 3 types of commercially available dental composite resins (macrofilled, hybrid and microfilled type) were determined using three point bend specimens. Acoustic Emission (AE), which is the generation of elastic wave due to the release of energy from the localized sources in material, was also detected during the fracture toughness test. Fracture surfaces were examined by scanning electron microscope. The fracture toughness values, AE patterns, and the nature of fracture surface were analyzed to understand fracture behavior of dental composite resins and fracture mechanism for each dental composite resin are proposed.

The authors describe electrochemical etching and sand-blasting of Ni-Cr alloys (Wiron-88, Nidemet-K) for adhesive bridges.

Various samples of two commercial dental mercuries were tested by chemical analyses with regard to metallic impurities (Fe, Cu, Ni, Zn, Mn, Cd, As, Tl, AG, Au). The surfaces of some of the tested samples were no longer bright and clear. The detectable metallic impurities reached a maximum of about 2 ppm.

The clinical applications possibilities and indication--fields of the composite Concise Enamel Bond System were examined within a 10 months observation period and compared with other plastic composites.