Reproduction of details using dental stones and investment material in impressions of elastomers and waxes.

In the fabrication of crowns and inlays it is very important that all the details of the impression are exactly reproduced by the cast. These requirements prevail between elastomeric impression materials and dental stones as well as between waxes and investment materials. Inadequate filling of the details of the impression will result in rounded inner corners of the casting, which then may not properly seat on the prepared tooth. Two brands of elastomeric impression material, dental stone, wax, investment material and wetting agent were chosen to study the reproduction of details. A master model of stainless steel, shaped like a truncated cone with a convex top and 60 degrees threads, was used. The shape of this model made it possible to make microscopic measurements of the reproduced detail of the threads. No significant difference, by different prepouring treatment of the impressions was found in reproducing details with elastomeric impression materials and dental stones. All combinations of elastomeric impression materials and dental stones reproduced, however, significantly more details than combinations of waxes and investment materials. The relevance of transferring conclusions from the laboratory investigation to clinical conditions are discussed as well as the clinical value of reproducing details.