Flow properties of dental impression materials by means of a modified sharkfin test at clinically relevant times after mixing

Abstract

Objectives: The aim of this study was: (1) To determine the relevant processing times for clinical practice. (2) To analyze the flow properties of several elastomeric impression materials depending on these clinically measured times by means of the modified sharkfin test. Methods and materials: (1) Clinical trial: The processing times of 86 clinical cases were measured by the same person. The impressions were taken by 14 different clinicians with the one-step technique (Impregum-Penta as regular body and Permadyne Garant 2:1 as light body). (2) Laboratory trial: On the basis of the clinical results, the sharkfin test was performed at the times of the 10th and 90th precentiles and the median value at 50 s, 26 s, and 81 s. 11 impression materials were tested: Regular materials (1. Aquasil Ultra Monophase. 2. Aquadyn Medium Soft Quick. 3. Aquadyn Medium Soft regular. 4. Aquadyn Medium Transfer. 5. Impregum Penta. 6. Impregum Penta Soft. 7. Impregum Penta Soft Quick. Light materials ( 1. Aquasil Ultra LV. 2. Aquadyn Light. 3. Impregum Garant L DuSoft. 4. Permadyne Garant 2:1). Two sizes of molds were used, 2 mm wide at the base for regular materials and 1 mm for light materials. The materials and the receptacle were brought to 23 °C and the entire assembled housing unit was brought to 35 °C to simulate the clinical conditions. Five experiments were made with each material and each of the three clinically measured times. Results and discussion: The experiments produced sharkfins and yielded flowcurves. The heights of the sharkfins were measured, and from the flowcurve data difference curves were made, in order to calculate the equilibrium points. Mean values, mean flow curves, and statistical analysis of all results at each clinically measured time were made. The longest clinically measured time (81 s) was regarded the most important one to characterize the flow properties. The results of every material at each time were compared to each other. Therefore, all the tested materials at all clinically measured times performed acceptable sharkfins. However, a very important point was significantly noticed, that Aquasil light and regular body gave very poor results compared to the other materials. At 81 seconds Aquasil Ultra Monophase was barely sufficient ). The light materials showed better flow properties than regular materials. The materials of polyether base show such a high ability of flowing independent of the temperature of the entire assembled unit which was adapted to the mouth temperature. The impregum-P-S-Q showed superior flow property, in addition to a reasonable sharkfin. According to the manufactur’s recommended working time (60 seconds), Impregum-P-S-Q was not supposed to give good results at 81 seconds. This study showed that the new materials on silicon base have a similar behavior like polyether concerning the flow properties.

In dieser Studie wurden sowohl experimentelle als auch handelsübliche Abformmassen hinsichtlich ihres Fliessverhaltens mit Hilfe des Sharkfin Tests und in Anlehnung an klinisch gemessenen Zeiten geprüft.