A study on metal release of tin ion-plated stainless steel orthodontic appliances / 대한치과교정학회지

This study was conducted to examine the metal release of TiN-plated stainless steel orthodontic appliances by constructing the simulated orthodontic appliances equivalent to maxillary half arch, by dividing into TiN-plated and TiN-nonplated groups and by dividing again these groups into welded and nonwelded groups. And then, the total quantity of metal release was obtained by measuring the amounts of both soluble and precipitated nickel and chromium after immersing in artificial saliva for 15 days. And then, the corrosion appearance of surface structure was observed by using SEM. The results of this study were summarized as follows. 1. The total amounts of released nickel and chromium showed that the TiN-plated group after welding (Group I) was 25.46microgram, respectively, and 17.4microgram, while the TiN-nonplated group after welding(Group III) was 54.69microgram, respectively, and 85.27microgram. Then, the TiN-plated group indicated less amounts of metal release(p<0.05). 2. The total amounts of the TiN-plated group without welding (Group II) was 0.05microgram and 0.34microgram, respectively. Then, it was shown that the TiN-plated group without welding(Group II) indicated less metal release than that of the TiN-plated group after welding(Group I)(p<0.01, p<0.05). 3. When observing their surface structure, there were a lot of precipitate and pitting corrosion in the groups with welding(Group I & III), when the TiN-plated group(Group I) showed lower level than the TiN-nonplated group(Group III). On the other hand, the groups without welding(Group II & IV) indicated a little of pitting corrosion. 4. In case of observation with the naked eyes, it was shown that there were significant discoloration and corrosion in the groups with welding(Group I & III), while there was no any remarkable change in the groups without welding(Group II & IV).

An experimental study on the cytotoxicity of recycled brackets / 대한치과교정학회지

The purpose of this study was to evaluated the cytotoxicity of brackets which were recycled thermally or chemically. New brackets and used brackets which had been in mouth for at least 2years were used as samples and human gingival cell culture and agar overlay technique was used to evaluate the cytotoxicity. From the experiment the following results were obtained: 1. New brackets in the as received state showed mild cytotoxicity. 2. Thermally recycled brackets except the used bracket not electropolished showed moderate cytotoxicity and among them new brackets showed greater cytotoxicity than used ones. 3. Used brackets which were thermally recycled without electropolishing showed mild cytotoxicity. 4. Among thermally recycled brackets, electropolished brackets showed greater cytotoxicity than not electropolished ones. 5. Chemically recycled brackets showed moderate cytotoxicity, and among them, new brackets appeared to be more cytotoxic than used ones.