Porcelain surface roughness, color and gloss changes after orthodontic bonding.

The purpose of this study was to evaluate the alteration in surface characteristics after orthodontic debonding of two types of porcelain systems commonly used in prosthetic dentistry. For this purpose, porcelain specimens were fabricated from low-fusing (n = 20) and high-fusing (n = 20) porcelain. The baseline surface roughness, color, and gloss were evaluated using profilometry, color shade index, and gloss study. All specimens were bonded with brackets and debonded using a testing machine at a rate of 0.1 mm/minute crosshead speed. The porcelain surfaces were polished using a 12-fluted carbide composite removal bur (low-fusing, n = 20; high-fusing, n = 20). In addition, half of each porcelain group was further polished using a series of Sof-Lex discs (low-fusing, n = 10; high-fusing, n = 10). The postdebond porcelain surface characteristics roughness, color, and gloss were reevaluated and compared with baseline measurements. The results were analyzed with two-way analysis of variance and Tukey multiple comparisons test, with porcelain type (low-fusing or high-fusing) and polishing protocol (carbide bur or carbide bur and discs) serving as discriminate variables at alpha = 0.05 level of significance. Bonding and debonding increased all roughness parameters tested; however, no change was revealed between the two polishing protocols. Similarly, gloss and color index changes were significantly altered after resin grinding, regardless of the polishing method used. No difference was identified between the two porcelain types with respect to roughness, color index, or gloss. Orthodontic bonding alters the porcelain surfaces, and postdebond polishing does not restore the surface to the prebond state.

Effects of root-end filling materials on fibroblasts and macrophages in vitro.

OBJECTIVE: The aim of this study was to investigate the effects of 4 root-end filling materials (mineral trioxide aggregate [MTA], intermediate restorative material [IRM], amalgam, and Retroplast) on cell growth, cell morphology, and cytokine (interleukin [IL]1beta and IL-6) production in mouse fibroblasts and macrophages. STUDY DESIGN: Millipore culture plate inserts with freshly mixed or set root-end filling material were placed into 6-well cell culture plates with already attached mouse fibroblasts or macrophages. Cells cultured with only the Millipore culture plate inserts served as a control. After a 3-day incubation, cell morphology was examined, and the total cell number per well was counted and analyzed by using 1-way analysis of variance. For cytokine assay, mouse macrophages were incubated in 24-well flat-bottom plates with set root-end filling material disks in the bottom. Cells cultured without the material disks served as negative controls, and cells cultured with lipopolysaccharides served as positive controls. After 24-hour incubation, culture media were collected for cytokine assay by using enzyme-linked immunosorbent assay. RESULTS: All root-end filling materials inhibited the cell growth of mouse fibroblasts and macrophages. There was no growth in the originally seeded cells in the fresh IRM, the fresh Retroplast, and the set IRM group. There was no difference between MTA and amalgam for cell growth either in the fresh material groups or in the set material groups. The total cell number in the set Retroplast group was significantly less than that in the set MTA group. Morphologically, MTA was characterized by denatured medium proteins and dead cells adjacent to the material, which were observed only in the fresh MTA group. There was no detected cytokine production in any of the tested material groups. CONCLUSION: All root-end filling materials inhibited cell growth, and none induced IL-1beta and IL-6 production.