Abstract:

Objective To investigate the feasibility of round-shape pin-hole marker measurement of irregular alginate dental impression deformation. Methods The metal model simulating abutment preparations was obtained, which had triangle-formed circular needles on the surface. Two types of alginate impression (Alginoplast and Palgat Plus, n=10 for each material) made by the metal model had the corresponding pin-hole markers. The dimensional changes of the markers after model withdrawl were observed by stereomicroscopy. The data of coordinates 0 min, 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 15 min and 20 min after model withdrawl were output by the software which could simulate the center of a circle to measure the displacement and impression accuracy (additional time point of 30 min after model withdrawl for CG length recording), and the linear dimensional change rates of impression samples were calculated. Results The outline of the pin-hole marker was clear, and the values of center coordinates were well repeated. The linear dimensional change rate of Alginoplast impression samples was 0.38% 20 min after model withdrawl, and that was 0.45% for Palgat Plus impression samples. For Alginoplast impression samples, the coordinate increased by 0.040% （8.4 μm） 2 min after model withdrawl, and decreased by 0.237% （49.4 μm） 30 min after model withdrawl. For Palgat Plus impression samples, the coordinate increased by 0.068% （14.2 μm） 2 min after model withdrawl, and decreased by 0.189% （39.5 μm） 30 min after model withdrawl. Conclusion The roundshape pin-hole marker measurement of irregular alginate dental impression deformation is feasible.

Key words: dental impression, round shape, pin-hole marker, impression deformation