PubMed · 13313334
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Liaras, J Houel. [Post-traumatic constrictive pericarditis].. https://pubmed.ncbi.nlm.nih.gov/13313334/
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Sterilization capability is a necessary requirement for any material that is to be used in a medical application. Therefore, it is necessary for apatite cement (AC) to be sterilized. Because there is little information on the sterilization methods of AC, the aims of this investigation were to evaluate the effects of various sterilization methods, including steam, dry heat, ethylene oxide (EtO) gas, and gamma irradiation sterilizations, on the setting and mechanical properties of AC. In the case of steam sterilization, because AC powder aggregated before setting-time measurements, the setting time could not be measured. When the powder was sterilized by dry heat or EtO gas, the setting time was prolonged significantly and the wet diametral tensile strength (DTS) value decreased significantly. Therefore, sterilizations with steam, dry heat, or EtO gas were suggested to be inappropriate methods for AC. Accordingly, the following experiments focused on gamma sterilization. The setting time of AC was retarded with an increase in gamma irradiation dose. The wet DTS value decreased with the increase in gamma irradiation dose. There was no compositional change due to the gamma irradiation. The following tests were carried out in order to examine the effect of the gamma irradiation on the setting reaction of AC in detail. Tetracalcium phosphate [TTCP: Ca(4)(PO(4))(2)O] and dicalcium phosphate anhydrous (DCPA: CaHPO(4)) were separately irradiated, and the cements were produced with the use of irradiated powder and nonirradiated powder. Although the wet DTS value of AC produced from irradiated TTCP and nonirradiated DCPA decreased with increasing gamma irradiation dose, there was no significant difference. In contrast, the wet DTS value of AC produced from irradiated DCPA and nonirradiated TTCP significantly decreased with the increase in gamma irradiation dose. In conclusion, although the detailed mechanism of the delayed setting time and decreased DTS value was not clarified by the present study, it was found that gamma irradiation affected DCPA more than TTCP.
The aim of this in vitro study was to evaluate dentin bond strength and marginal adaptation of direct resin composite fillings after different storage times. Three hundred sixty cavities were prepared in discs of freshly extracted human third molars and filled with resin composites. Multistep self-etching adhesives (Syntac Classic, A.R.T. Bond, both with and without total etching), three-step etch-and-rinse adhesives (Scotchbond Multi-Purpose Plus, EBS), and two-step etch-and-rinse adhesives (Prime and Bond 2.0, Syntac Single-Component) were used for bonding. After 1, 90, and 2190 days of water storage and 24 h thermocycling (1150 cycles), push-out testing was performed. From the 6-year group, replicas were made after 1 day, 90 days, and 1, 2, 3, 4, 5, and 6 years, and examined regarding marginal adaptation under an SEM (x 200 magnification). In all groups under investigation, push-out bond strengths remained stable after 90 days; however, the strengths significantly decreased after 6 years of water storage. The two-step systems exhibited lower bond strengths than three-step systems after 6 years. Marginal analysis revealed a significant loss regarding the percentage of perfect margins having been stable after 2 years for the three-step etch-and-rinse systems. Overall, the older three-step systems proved to be more effective than the simplified adhesives Syntac Single-Component and Prime and Bond 2.0 with regard to bond strength and marginal adaptation.