| Abstract: | Earlier published measurements of the polymerization shrinkage and water-absorption expansion of plastic filling materials are often difficult to relate to the clinical application of the materials. In the present work an attempt has been made to rectify this situation. The following materials were investigated: Adaptic, Addent XV, Blendànt, Concise, D.F.R., Palakav, capsulated Palakav, TD 71, Palavit 55, Sevriton Simplified and Swedon. The filling materials were placed in cavities cut in extracted teeth. Dimensional changes of the fillings were measured in a microscope. The complete investigation was conducted in a thermostat room maintained at 37°C. The fillings were examined either shortly after initial set or after varying periods of immersion in water. Immediately after initial set a marginal gap at both the enamel and dentin levels of the walls was observed. Polishing the fillings at this time resulted in a zone of fractured enamel 20—40 microns wide. If the fillings were stored in water, the width of the marginal gaps was reduced; for some brands the gaps were completely closed in less than 32 days. Polishing of fillings with closed shrinkage gaps resulted in a minimum of fractures of the enamel margins. |
