ABSTRACT
The aim of this study was to evaluate the effect of dental surface treatment with Erbium-Doped Yttrium Aluminum Garnet[Er: YAG], Neodymium-Doped Yttrium Aluminium Garnet[Nd: YAG] and Carbon Dioxide Laser [CO[2]] lasers and sodium ascorbate to recently home bleached enamel by scanning electron microscope [SEM]. Thirty extracted human third molars were selected for this in vitro study. The teeth were randomly divided in two groups including home bleached group and control group [non-bleached]. In group 1, the samples were bleached by home bleach technique. No bleaching procedure was done in second the group which served as control group. Then, the samples of two groups were divided to five subgroups as follow: Subgroup 1: treated using Nd:YAG laser with output power of 1 W, Subgroup 2: treated using Er:YAG laser with output power of 0.5 W, Subgroup 3: treated using CO[2] laser with output power of 0.5 W, Subgroup 4: sodium ascorbate 10%, Subgroup 5: no treatment. After treatments, the surfaces were evaluated using Scanning Electron Microscope [SEM] analysis. The surfaces treated by Nd:YAG laser showed some melting and recrystallized areas and in some area droplet pattern was observed. But the surface treated by Er:YAG laser showed irregular and micro porous surface with flake pattern. CO[2] laser treatment of home-bleached surfaces resulted in melting area and cracks. Sodium ascorbate did not change the home-bleached surface. Among different surface treatments used in this study, it seems that Er:YAG laser can best interact with home-bleached teeth.
Subject(s)
Lasers, Solid-State , Lasers, Gas , Ascorbic AcidABSTRACT
Tooth-colored non-metal posts are adhered to the canal walls with the use of resin cements and dentin adhesives. Degree of conversion of these cements is especially important to ensure the durability of the restoration. The present study aimed at evaluating the degree of conversion [DC%] of self-cure and dual-cure resin cements at different depths and time points when using a DT. Light Post. In this experimental study, metal molds with 5 and 10 mm heights and internal diameter of 0.8 mm were used. Posts were vertically placed in the center of molds. Spectrum of absorption of the dual cure cement was measured before curing using Fourier transform infrared [FTIR] spectroscopy device. The uncured samples were then removed from the device and placed beneath the molds. After light irradiation, samples were transferred again to the FTIR device and their spectrum of absorption was measured. DC% was calculated using the relevant formula. For self-cure cements, spectrum of absorption was measured at 0, 2, 5, 10 and 15 minutes by the FTIR. Results were statistically analyzed using SPSS software. Self-cure cement had a DC of 5% at 0, 2, 5 and 10 minutes and a DC of 20% at 15 minutes. DC of the dual-cure cement was 44%, 15% and 8% at 0, 5 and 10 mm depths, respectively. Two-way ANOVA and Tukey's Post Hoc test [HSD] revealed that in the dual-cure cement the DC at 5 and 10 mm depths was significantly different [P<0.05]. DC was 20% at 15 minutes which was the highest. DC% of the dual-cure cement was higher than that of the self-cure cement which is attributed to the optimal characteristics of the dual-cure cement and also the ability of fiber post to pass light