The objective of this study was to compare peri-implant bone formation among uncoated (UC), hydroxyapatite (HA), collagen plus hydroxyapatite (CH), and silk plus hydroxyapatite (SH) implant groups. Surface coating was applied using the aerosol deposition method. The morphology of MG63 cells on the implant surfaces were examined by scanning electron microscopy (SEM) after 8 h cultures on the each of implant groups. After 48 h cultures, MTT assay was performed to compare cell viabilities of each group. Subsequently, a total of 20 implants from each group were installed in the tibia of the rabbits. The animals were sacrificed at 6 weeks after the implant installation. The peri-implant bone formation was evaluated from the histological sections. In the SEM images, SH coating implant showed better attachment of MG63 cells to the implant surface than the other groups. It also showed adequate cell viabilities and peri-implant bone formations compared with other implant groups. From these in vitro and vivo experiments, SH coating can be a possible candidate for the surface treatment of dental implant. This study was supported by a grant from the Next-Generation BioGreen21 Program (Center for Nutraceutical & Pharmaceutical Materials no. PJ009013)

Establishment of emission concentrations of PCDDs and PCDFs in emission gases from 85 domestic crematories were measured. The relationship between PCDDs/DFs and several factors such as structure, equipment and operational state of the crematory is discussed. Furthermore, emission of PCDDs/DFs from all crematories in korea is estimated. The following results are obtained: (1) total concentration (2,3,7,8- substituted isomers) of PCDDs/DFs was 0.113 ~ 14.34 ng/ Sm3, whose TEQ concentration was 1.815 ng-TEQ/Sm3; (2) total emission of PCDDs/DFs from crematories in korea was estimated to be 1.815 g-TEQ/yr.