Comparison of Mechanical Properties of PEEK and PMMA: An In Vitro Study.

AIM: Evaluation and comparison of flexural strength and hardness of heat-cured polymethylmethacrylate (PMMA) denture base with polyetheretherketone (PEEK). MATERIAL AND METHODS: A total of 80 samples of PEEK and PMMA were prepared and divided into two groups: group A and group B, of 40 each. Both the groups were further divided into subgroups consisting of 20 samples of PMMA and PEEK. The group A specimens were tested for flexural strength by universal testing machine (UTM), and group B samples were subjected to hardness test using Vickers microhardness tester. The values obtained were subjected to statistical analysis. The readings were subjected to an unpaired t-test for comparison of flexural strength and hardness of PEEK and PMMA. RESULT: The flexural strength of PEEK was 183 MPa, while that of PMMA was 84 MPa. The hardness of PEEK and PMMA was 24 VHN and 19.4 VHN, respectively. CONCLUSION: It was observed that PEEK can be a potential denture base material with superior properties as compared to PMMA. Further researches are needed to be carried out. CLINICAL SIGNIFICANCE: PEEK as a denture base exhibits adequate flexural strength prolonging its clinical longevity and overcoming the most common reason for the failure of PMMA denture base that results in fracture.

Comparison of the Solubility of Conventional Luting Cements with that of the Polyacid Modified Composite Luting Cement and Resin-modified Glass lonomer Cement.

INTRODUCTION: This study was planned to find the solubility of the conventional luting cements in comparison with that of the polyacid-modified composite luting cement and recently introduced resin-modified glass ionomer cement (RMGIC) with exposure to water at early stages of mixing. MATERIALS AND METHODS: An in vitro study of the solubility of the following five commercially available luting cements, viz., glass ionomer cement (GIC) (Fuji I, GC), zinc phosphate (Elite 100, GC), polyacid-modified resin cement (PMCR) (Principle, Dentsply), polycarboxylate cement (PC) (Poly - F, Dentsply), RMGIC (Vitremer, 3M), was conducted. For each of these groups of cements, three resin holders were prepared containing two circular cavities of 5 mm diameter and 2 mm depth. All the cements to be studied were mixed in 30 seconds and then placed in the prepared cavities in the resin cement holder for 30 seconds. RESULTS: From all of the observed luting cements, PMCR cement had shown the lowest mean loss of substance at all immersion times and RMGIC showed the highest mean loss of substanceat all immersion times in water from 2 to 8 minutes. The solubility of cements decreased by 38% for GIC, 33% for ZnPO4, 50% for PMCR, 29% for PC, and 17% for RMGIC. CONCLUSION: The PMCR cement (Principle-Dentsply) had shown lowest solubility to water at the given time intervals of immersion. This was followed by PC, zinc phosphate, and GIC to various time intervals of immersion.