ABSTRACT
STATEMENT OF PROBLEM: A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed. PURPOSE: We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability. MATERIAL AND METHODS: Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants (20 nm TiO(2) coating surface, heat-treated 80 nm TiO(2) coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media (RBM) surface, sandblast and acid-etched (SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. Periotest® & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done. RESULTS: In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants. CONCLUSIONS: In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.
ABSTRACT
STATEMENT OF PROBLEM: When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered. PURPOSE: The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment. MATERIAL AND METHODS: The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera™, Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at 25â for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-5®, United Calibration, USA). These values were statistically analyzed. RESULTS: 1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order. CONCLUSION: Within the limitations of this study, all methods of surface treatment used in this study are clinically available.
ABSTRACT
Nitric oxide (NO) is associated with many pathophysiology of the central nervous system including brain ischemia, neurodegeneration and inflammation. Epigallocatechin gallate (EGCG) is a major compound of green tea polyphenol that has shown the protective activity against neuronal diseases. This study examined the effect of EGCG on NO-induced cell death in PC12 cells. The administration of sodium nitroprusside (SNP), a NO donor, decreased the cell viability and induced apoptosis showing characterization such as cell shrinkage and chromatin condensation as well as subG1 fraction of cell cycles. EGCG inhibited the cytotoxicity and apoptotic morphogenic changes induced by SNP. EGCG attenuated the production of reactive oxygen species (ROS) by SNP, and ameliorated the SNP-induced Bax to Bcl-2 expression ratio leading to apoptosis. In addition, EGCG prevented the release of cytochrome c from the mitochondria into the cytosol as well as the upregulation of the voltage-dependent anion channel (VDAC), a cytochrome c releasing channel, in the mitochondria of SNP-treated cells. EGCG abrogated the activation of caspase-9, caspase-8 and caspase-3 induced by SNP. These results demonstrate that EGCG has a protective effect against SNP-induced apoptosis in PC12 cells by scavenging ROS and modulating the signal molecules associated with cytochrome c, caspases, VDAC and the Bcl-2 family. These findings suggest that EGCG might be a natural neuroprotective substance.
