Ureporn Kedjarune-Leggat

The effect of acidic agents on surface ion leaching and surface characteristics of dental porcelains

STATEMENT OF PROBLEM Acidic food and sour fruits and drinks have been investigated for their destructive effects on enamel. However, their effect on porcelain restorations has not been widely examined. PURPOSE The purpose of this study was to evaluate the ion leaching of porcelains immersed in acidic agents. MATERIAL AND METHODS Fifty-five discs (12.0 mm in diameter and 2.0 mm in thickness) were made from each of 4 types of porcelain (VITA VMK 95, Vitadur Alpha, IPS Empress Esthetic, and IPS e.max Ceram). Baseline data of elemental compositions of all storage agents were recorded. Four groups of discs (n=10) were then immersed in acidic agents (citrate buffer solution, pineapple juice, and green mango juice) and deionized water (control) at 37 degrees C for 168 hours. One group was immersed in 4% acetic acid at 80 degrees C for 168 hours. After immersion, fluids from all specimens for each acidic agent were measured for ion leaching with an inductively coupled plasma optical emission spectroscopy. Surface characteristics of specimens were examined using scanning electron microscopy (SEM). Data were analyzed using 3-way repeated ANOVA and Tukey HSD multiple comparisons (alpha=.05). RESULTS This study revealed that each type of porcelain had significantly leached the various ions to varying degrees after being immersed in acidic agents (P<.001 for all comparisons). SEM photomicrographs showed surface destruction of all porcelains. CONCLUSIONS Acidic agents used in this study affected elemental dissolution of the 4 types of porcelains evaluated.

Chemical durability and microhardness of dental ceramics immersed in acidic agents.

Abstract Objective. To evaluate the microhardness and surface elemental compositions of ceramics immersed in acidic agents. Material and methods. Thirty-five ceramic disc specimens were made from each of four types of ceramic (VMK 95, Vitadur Alpha, Empress Esthetic and IPS e.max Ceram). Before immersion, baseline data of Vickers microhardness and elemental composition were recorded. Four groups of discs (seven per group) were then immersed in acidic agents (citrate buffer solution, pineapple juice and green mango juice) and deionized water (as a control) for 168 h at 37°C. One group was immersed in 4% acetic acid at 80°C for 168 h. After immersion, specimens were evaluated and data were analyzed using two-way ANOVA with repeated measurements and a paired t-test at a significance level of 0.05. Results. The microhardness values of four types of ceramic significantly decreased after being immersed in acidic agents (p < 0.05). The elemental compositions of ceramics mainly comprise silicon, aluminium and potassium. These compositions also decreased after immersion (p < 0.05). Conclusions. The acidic agents used in this study affected the microhardness and elemental dissolution of ceramics. The main elemental compositions of ceramics (silicon, aluminium and potassium) decreased after being immersed in acidic agents.

Effect of novel chitosan-fluoroaluminosilicate glass ionomer cement with added transforming growth factor beta-1 on pulp cells.

INTRODUCTION Vital pulp therapy might benefit from the sustained release of transforming growth factor beta-1 (TGF-β1) from dental restorative materials. Chitosan has previously been shown to enable sustained release of bovine serum albumin (BSA) from glass ionomer cement (GIC). Because BSA can prolong release of growth factor, chitosan-fluoroaluminosilicate GIC with albumin (BIO-GIC) should sustain the effect of growth factor. This study investigated the effect of BIO-GIC with added TGF-β1 on pulp cells. METHODS BIO-GIC was prepared from GIC (conventional type) incorporated with 15% of chitosan and 10% of BSA. TGF-β1 (100 ng) was added in BIO-GIC+TGF-β1 and GIC+TGF-β1 groups during each disk specimen (10 mm diameter, 1 mm high) preparation. Two control groups were BIO-GIC and GIC. The effect of each specimen on pulp cells was investigated by using the Transwell plate technique. Cell proliferation was determined by MTT assay at 2 time periods (each period lasting 3 days). Pulp cell differentiation was examined by alkaline phosphatase activity and also by cell mineralization, which was measured by calculating the area of mineralization with von Kossa staining. RESULTS Percentage of viable cells of GIC+TGF-β1 group was the highest after the first period. This might suggest an initial rapid release of TGF-β1 from GIC. After the second period, BIO-GIC, BIO-GIC+TGF-β1, and GIC+TGF-β1 had more than 90% cell survival. It was significantly greater than GIC (82% ± 2%). There was no significant difference in alkaline phosphatase activity. BIO-GIC+TGF-β1 had the highest mineralization area during 21 days. CONCLUSIONS BIO-GIC could retain the effect of TGF-β1.

Bovine serum albumin release from novel chitosan-fluoro-aluminosilicate glass ionomer cement: Stability and cytotoxicity studies

OBJECTIVE This study aimed to evaluate the effect of adding chitosan (CS) to conventional glass ionomer cement (GIC) on protein release and its cytotoxicity. METHODS Bovine serum albumin (BSA) was used as the released protein from two glass ionomer formulations. One (GIC+BSA) contained fluoro-aluminosilicate glass mixed with BSA, and another (GIC:CS+BSA) used a similar glass and BSA with 20% chitosan. Six disc specimens per group (10mm in diameter, 2mm in height) were prepared and placed in phosphate buffer saline, which was replaced at various times over 2 weeks. The released protein was determined by a BCA assay. Cytotoxicity of the extracts from these materials for 1, 2 and 7 days to dental pulp cells was evaluated using MTT assay. RESULTS The GIC:CS+BSA released a burst of BSA in the first 6h, and slowly released at different rates over the 2 weeks. GIC+BSA showed a similar result, but protein could not be detected at the 12h. The protein release rate of GIC:CS+BSA was significantly greater than GIC+BSA (P<0.01); nearly three times higher. The released BSA had the same molecular weight as evaluated by SDS-PAGE. From the MTT assay, the percentages of viable cells were significantly different and can be arranged as: GIC:CS+BSA>GIC:CS>GI+BSA>GI and the cytotoxicity was increased by time of extraction. CONCLUSION Chitosan added in glass ionomer cement can prolong release of BSA as well as not increasing the toxicity to pulp cells. This material may be useful for protein delivery.

Ultrasound treatment increases transfection efficiency of low molecular weight chitosan in fibroblasts but not in KB cells.

The aim of this study was to optimize transfection efficiency (TE) of the depolymerized low molecular weight (LW) chitosan with molecular weight (Mw) at 16 kDa and 54% degree of deacetylation (DDA) on three primary cells of fibroblast (F), dental pulp (P), and periodontal ligament (PDL). The effect of low frequency ultrasound treatment on the chitosan-DNA complexes prior transfection on TE was also evaluated. This LW chitosan required high N/P ratio (>34) to bind DNA completely. An N/P ratio above 56 tended to improve TE in most primary cells nearly at the level of Lipofectamine. Ultrasonication can reduce the aggregation and sizes of the chitosan-DNA microparticles. It increased TE of F cells at an N/P ratio above 34, which was higher than Lipofectamine. However, this ultrasound treatment caused loss of TE in KB cells. MTT assay of these chitosan-DNA complexes revealed no significant cytotoxicity to both KB and F cells. This LW chitosan has potential for further development into a safer alternative to gene delivery systems in various cells of interest; however the optimal conditions have to be adjusted, depending on each cell source.

Expression of translationally controlled tumor protein in heat-stressed human dental pulp cells.

OBJECTIVE The aim of this study was to investigate the effects of heat stress on cell viability, translationally controlled tumor protein (TCTP) expression, and the effects of recombinant TCTP on heat-stressed human dental pulp cells (HDPCs). METHODS HDPCs were isolated from human teeth and cultured at 37°C. For heat stress, HPDCs were incubated at 43°C for 45min. After heat stress, recombinant TCTP were added to HDPCs and cultured for various periods of time at 37°C. Heat-treated cells were then analyzed by DNA staining with Hoechst 33258, MTT, and caspase 3 activity assays. TCTP expression level was assessed by real-time PCR and western blot analysis. RESULTS Heat-treated cells displayed lower cell density and nuclear morphology resembling apoptotic body. Heat stress significantly decreased cell viability and induced activity of caspase 3. The effect of recombinant TCTP on pulp cell death from heat stress varied depending on each subject and TCTP concentration. Heat stress up-regulated TCTP mRNA expression level. In contrast, TCTP protein level remained unchanged. Recombinant TCTP did not affect TCTP mRNA expression but down-regulated TCTP protein in heat-treated cells. CONCLUSIONS Heat stress induces caspase 3 activation and up-regulates TCTP mRNA expression in HDPCs. TCTP did not play a key role on pulp cell recovery from heat stress.

3D interconnected porous HA scaffolds with SiO2 additions: Effect of SiO2 content and macropore size on the viability of human osteoblast cells†

3D interconnected porous scaffolds of HA and HA with various additions of SiO2 were fabricated using a polymeric template technique, to make bioceramic scaffolds consisting of macrostructures of the interconnected macropores. Three different sizes of the polyurethane template were used in the fabrication process to form different size interconnected macropores, to study the effect of pore size on human osteoblast cell viability. The template used allowed fabrication of scaffolds with pore sizes of 45, 60, and 75 ppi, respectively. Scanning microscopy was used extensively to observe the microstructure of the sintered samples and the characteristics of cells growing on the HA surfaces of the interconnected macropores. It has been clearly demonstrated that the SiO2 addition has influenced both the phase transformation of HA to TCP (β-TCP and α-TCP) and also affected the human osteoblast cell viability grown on these scaffolds.

Translationally controlled tumor protein supplemented chitosan modified glass ionomer cement promotes osteoblast proliferation and function.

The objective of this study was to evaluate the effect of translationally controlled tumor protein (TCTP) supplemented in a novel glass ionomer cement (BIO-GIC) on normal human osteoblasts (NHost cells). BIO-GIC was a glass ionomer cement (GIC) modified by adding chitosan and albumin to promote the release of TCTP. NHost cells were seeded on specimens of GIC, GIC+TCTP, BIO-GIC and BIO-GIC+TCTP. Cell proliferation was determined by BrdU assay. It was found that BIO-GIC+TCTP had significantly higher proliferation of cells than other specimens. Bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) gene expressions assessed by quantitative real time PCR and alkaline phosphatase (ALP) activity were used to determine cell differentiation. Bone cell function was investigated by calcium deposition using alizarin assay. Both BMP-2 and OPN gene expressions of cells cultured on specimens with added TCTP increased gradually up-regulation after day 1 and reached the highest on day 3 then down-regulation on day 7. The ALP activity of cells cultured on BIO-GIC+TCTP for 7 days and calcium content after 14 days were significantly higher than other groups. BIO-GIC+TCTP can promote osteoblast cells proliferation, differentiation and function.

The Recovery Effect of the Translationally Controlled Tumor Protein in 2-Hydroxy-Ethyl Methacrylate-Treated Human Dental Pulp Cells

2-Hydroxy-ethyl methacrylate (HEMA) is a major monomer released from resin-base dental restorative materials. This study examined the recovery effect of the Translationally Controlled Tumor Protein (TCTP) in human dental pulp cells (HDPCs) after exposed to HEMA. TCTP from banana prawn (Penaeus merguiensis) was cloned and the protein was purified. A real-time cell analyzer was used to evaluate cell survival. The cell suspensions were seeded into an E-plate 96 at 8,000 cells/ well. After 24 hours, HDPCs were treated with 8 mM HEMA mixed in culture medium (alpha modified Eagles medium, α-MEM) for 1 hour before the medium supplemented with TCTP at 0, 100 ng/ml, 1 μg/ml, 10 μg/ml was replaced and left for 23 hours. After that, cells were fed with fresh medium for 72 hours. The cell indexes were monitored every 15 minutes and the 1-way analysis of variance (ANOVA) was used for statistical analysis. Real-time xCELLigence impedance analysis indicated that the cell indexes reached to 0 after treated with HEMA for 1 hour. TCTP at 1 μg/ml was significantly (P < 0.05) increased the cell index of HEME-treated HDPCs from 0 to 0.02 and 0.04 after TCTP exposure for 1 hour and 23 hours, respectively. It was suggested that TCTP has an ability to recover the cytotoxic effect of HEMA-treated pulp cells.