In situ replication techniques: II. Quantitative methodologies for replicate materials

Abstract

Because replicate materials have requirements different from those of recording or impression materials, quantitative methodologies were sought using commercial impression materials. Two satisfactory objective techniques resulted, a laser-scattering and a capillary flow test. Using high-resolution gratings to stimulate tooth detail (less than 1 micron), the reproduction quality of 36 two-stage replicas was determined in diffraction, reflection, and in an unblazed state. Using precision bore glass tubes (0.25, 0.5, 1, and 2 mm diameters) to simulate the high-energy surface of enamel, the flow characteristics of nine elastomers (the first stage replicates) and four epoxies (the second stage replicates) were determined at isobaric conditions. Because the laser spot size was relatively large (0.6 mm) and the pressure differential was small (25 mm Hg), both the global resolution and the low shear rate characteristics could be measured. Of the commercial materials tested, Reprosil Light had the best combination of fluidity and resolution, regardless of which positive material was used. Although Permagum Low, Silene Wash, and Xantopren Blue scored high in one of the two tests, none of these materials could compare to Reprosil Light within the context described herein.

Methods of clinical evaluation of dental restorative materials

“…A method designed to test the accuracy of various impression materials when used for this procedure showed the addition-cured silicone materials to be the most accurate (Kusy & Whitley, 1985) although other workers have recommended the use of condensationcured silicone material (Hirt, Lutz & Roulet, 1984). A recent systematic inquiry into the use of high-resolution replica materials concluded that a standardization of technique would allow researchers to directly compare studies (Bromage, 1985).…”