Evaluation of Vickers Hardness Number of the five feldspathic ceramics

Objectives:The purpose of this study was to evaluate the Vickers hardness of the five feldspathic ceramics (D.sign (Ivoclar) DS; Duceram Plus (DeguDent) DP, Noritake EX3 (Noritake) NK, HeraCeram (Kulzer) HR and Duceragold (DeguDent) DG, before and after the simulation of occlusal adjustment. Methods: Twenty enamel ceramic discs with 7mm in diameter and 2 mm thickness were made and glazed for each material following the manufactorer's instructions and divided in two groups. The discs were stored in distilled water at 37oC for seven days. Group 1: Vickers hardness was measured using HMV-2000 (Shimadzu) with a load of 300 g by 30 seconds. Nine indentations were made in each sample. Group 2: the ceramic adjustment was made with a rotatory grinding instrument in order to simulate the occlusal adjustment, and polishing accomplished using an Edenta commercial finishing kit. The Vickers hardness was made identical in group 1. The data were submitted to variance analysis and Tukey's test (5%). Results: The Vickers hardness after the occlusal adjustment simulation and polishing (553.2 VHN) for DP was statisyically superior them others, (476.2 VHN) DS, (468.3 VHN) NK, (449.9 VHN) HR that did not showed statistically difference, but were superior to the DG (427,1 VHN). For the glazed ceramics DP (511.9 VHN) showed values statisyically superior them others DS (444.7 VHN); NK (442.2 VHN) HR (436.6 VHN) e DG (427.8 VHN) . Conclusion: The Duceram Plus presented higher values of Vickers hardness them others.