Effect of Surface Hardeners on a Physical Property of Type IV Gypsum Products

Abstract

Background: Gypsum products are being used for construction of dental prosthesis. Most of the researches done so far on gypsum materials are on its use as fixed and removable prosthodontics. And although many studies have looked at a multitude of means for altering its properties, relatively less has been explored on examining the abrasion resistance of the gypsum product itself. Objectives: The current study was done to determine the abrasion resistance of three commercially available type IV gypsum products on application of three die-hardeners when abraded with 20gm and 50gm load stylus. Methods: An experimental in vitro study was done in the Dept. of Prosthodontics, UP Dental College & Research Center and the Dept. of Pharmacy, BBD National Institute of Technology & Management, Lucknow. A standardized machined die was fabricated so that the die consisted of 27 vertical ridges of 1mm depth. Three type IV gypsum products viz., Kalrock, Elite Rock and Denstone Plus and three die-hardeners viz., Hartebad die-hardener, Handae die-hardener and Maarc die-hardener were included in the study. 40 samples were prepared from each of the die-stones by pouring into impressions made by using the putty-wash technique. Resultantly, 120 samples were prepared which were let to mature. These 120 samples were divided into 24 groups, each group consisting of 5 samples. They were grouped as uncoated, coated with Hartebad die-hardener, coated with Handae die-hardener and coated with Maarc die-hardener. They were sub-grouped further for abrading under 20gm and 50gm loads by using an abrasion-testing machine. After 10 oscillations, the loss of mass was measured using analytical electronic machine. The different findings were compared by using appropriate statistical analytic tests. Results: The abrasion resistance of type IV gypsum products increased with the application of surface-hardeners irrespective of the load and Elite Rock showed better abrasive resistance while Denstone Plus showed lesser abrasion resistance among all the type IV gypsum products tested. Conclusion: Elite Rock when coated with Hartebad die-hardener showed maximum abrasion resistance irrespective of the load applied.

To Evaluate and Compare the Effect of Commercially Available Model Hardening Agent on Surface Hardness and Surface Roughness of Refractory Investment Materials: An In-Vitro Study

“…Hence, to achieve the more desirable properties of surface roughness and surface hardness, refractory investment materials are commonly treated with surface hardening agent, surface coatings or various specific surface treatments. Several reports have been published regarding cast hardening agent that has significantly changed the mechanical and physical properties of various dental investment materials [7][8][9][10][11] . Another recent study conducted by Saji et al 2 , application of different hardening agents on two commercially available refractory materials.…”