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Light curing composite resins became the preferred material in treating carious or traumatic lesions of anterior teeth. Attempts to improve the properties of these materials lead to the development of hybrid composites with an amount of anorganic fillers of more than 80 weight %. It was the purpose of this study to investigate whether composites with higher amounts of anorganic filler show better properties than those with lower amounts of filler. Eight commercial and two experimental composites have been tested for their resistance to abrasion by simulated toothbrushing, polymerization shrinkage, water sorption, porosity, and surface quality. The results showed no correlation between the amount of anorganic filler on the one hand and tested properties on the other. The amount of anorganic filler is no quality criterium per se, the properties of a composite are rather influenced by composition and quality of the organic matrix, even if the amount of anorganic fillers increases to more than 80 weight %.

Eight commercial and two experimental light cured composite have been tested for color stability after experimental aging. Color differences were measured by computer-controlled spectrophotometry and expressed in terms of L*A*B* color coordinates (CIELAB). Although three composites with a high content of anorganic filler showed the best color stability and the material with the lowest anorganic filler content showed the greatest discoloration, there was no strong correlation between the amount of anorganic filler on the one hand and color stability after experimental aging on the other.

The reproduction of elastic impression materials is described with a laser-technique. This technique allows a quantitative evaluation without touching and deforming the surfaces. Although it is possible to measure differences, clinically relevant differences between several elastomere and one hydrocolloid material are not found.

The surface roughness of cast Titanium compared with a precious alloy (Au-Ag-Cu), two Pd-base alloys (Pd-Ag-Sn-In, Pd-Sn-Ga-Cu) and two base metal alloys (Ni-Cr-Mo, Co-Cr-Mo) was determined by surface profile measurements after polishing with six different polishing pastes. The results revealed the best surface quality for Au-Ag-Cu followed by Ni-Cr-Mo, Co-Cr-MO, Pd-Sn-Ga-Cu and Pd-Ag-Sn-In. The highest but still acceptable surface roughness was found with Ti.

The effects of several fluoride gels on ceramic surfaces (Dicor, Optec, Biodent ceramic and Vita VMK) were tested by SEM and by means of an electrical stylus instrument. After 10 min exposure time an acidulated gel (Oral-B Fluoride-Gel) showed a significant effect, whereas the effect of two non-acidulated gels (Elmex-Gelee, Blend-a-med Fluoride Gel) was not significant. After 24 h exposure time, Elmex and Blend-a-med gel showed an effect, too.

Glass fibers added to temporary crown and bridge material (Proviso-Blend, Blendax) by 5% to the weight increased the tensile strength of the acrylic resin by 38%. The increase was even greater when carbon fibers were added (50%), but the resin discoloured to a greyish shade. The results were less spectacular with Dentalon Plus (Kulzer), and the experiment did not work with Protemp (Espe). The amount of improvement in tensile strength depended on the type and geometry of the fiber and of the fiber concentration. Neither the properties of the polished surface of a fiber-reinforced acrylic nor adverse effects of such fibers possibly swallowed by the patient are investigated as yet.