In vitro and in vivo evaluation of locally produced dental porcelain

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Date
2007
Authors
All Abu Sharbeh, Hazem Yousef
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Abstract
Biocompatibility of dental porcelain is of crucial importance to the long-term success of dental prostheses because of· its close contact with oral tissues for extended periods. This study was designed to evaluate the biocompatibility of locally produced dental porcelain "test" using in vitro and in vivo methods. The in vitro cytotoxic potential of the test material was evaluated using test on extracts and direct contact test formats as per ISO 10993-5. Cell culture medium was used both as a control and an extractant. Additionally, a commercially available product was included to facilitate comparison of results. HOS cell line (ATCC, USA) was incubated for 72 hours with the extraction solutions of the test and commercial materials powders at various concentrations (50, 100, 150, 200 and 250 mg/ml). Similarly, MRC-5 cell line (ATCC, USA) was incubated for 72 hours with the test and commercial discs (5 mm in diameter and 2 mm thick). Aging process was carried out by submerging the discs into 3% Bovine Serum Albumin (BSA) solution for 96 hours followed by reincubation with the MRC-5 cell line. Cellular response was assessed using MTT [3-( 4,5-Dimethylthiazol-2-yl)-2 ,5-Diphenyltetrazolium Bromide] assay for measuring the mitochondrial succinate dehydrogenase (SDH) activity of living cells. Optical densities were measured at 570 nm using ELISA (Enzyme Linked lmmunosorbent Assay) reader and then converted to a percentage of the control for each cell culture well. Results were compared using one-way ANOVA and Tukey Post-Hoc comparisons at a significance level of P <0.05. For in vivo study, materials discs were implanted subcutaneously into 12 Sprague-Dawley male albino rats, which were sacrificed in groups of 3 at 1, 2, 3 and 4 weeks after implantation. A semi-quantitative histological analysis of the tissue surrounding implanted discs was done under an image analyzer. In vitro cytotoxicity test on extracts showed that the test material was significantly different from the control at concentrations higher than 150 mg/ml. The mean(SD) percentage of cellular viability was 102.2(12.8) for 50 mg/ml, 98.9(10.3) for 100 mg/ml, 89.4(15.8) for 150 mg/ml, 86.7(14.6) for 200 mg/ml and 82.9(16.5) for 250 mg/ml. However, the commercial product was significantly different from the control at concentrations higher than 50 mg/ml. The mean(SD) percentage of cellular viability was 95.6(14.5) for 50 mg/ml, 85.4(12.4) for 100 mg/ml, 81.5(14.8) for 150 mg/ml, 80.7(14.5) for 200 mg/ml and 79.3(10.9) for 250 mg/ml. Direct test showed that the materials after aging were not significantly different from the control. The mean(SD) percentage of cellular viability was 89.2(13.4) for the test and 89.4(14.6) for the commercial. The materials tested were already significantly different from the control before the conditioning of BSA. The mean(SD) percentage of cellular viability was 88.5(12.1) for the test and 88.5(8.9) for the commercial. However, in both tests, the materials caused mild suppression of SOH activity ( <25% of control), which is considered to be accepted clinically. In vivo subcutaneous implantation showed that the macrophage was clearly the dominant cell type at the implant surface at the first week after implantation, followed by a gradual decrease as the implantation period increased. On the contrary, fibroblasts and fibrocytes were the dominant cell types in the tissue surrounding test and commercial discs at the third and fourth week after implantation. These findings, from pathological point of view, might be an indicator of biocompatibility.
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Dental porcelain
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