RESUMEN
Objectives: the aim of this study was to compare the microtensile bond strengths [micro TBS] of three core materials with one lithium disilicate reinforced ceramic using two resin cements
Methods: three core materials [Nulite F[registered sign] [Biodental Technologies], Filtek Z250[registered sign] [3M-ESPE], Prettau-Anterior[registered sign] [Zirkonzhan, Germany]] were prepared as blocks [10×10×4 mm3] according to the manufacturer's instructions. Lithium disilicate ceramic blocks were also constructed and bonded to core specimens with two dual curing luting resin cements [Duo-Link[registered sign] [Schaumburg, IL], Bifix QM[registered sign] [VOCO, Cuxhaven, Germany]]. Micro-bar specimens were prepared and loaded in tension to determine the micro TBS Failure modes were classified by scanning electron microscope [SEM]. Data were analysed using two-way ANOVA and Tukey HSD test
Results: the micro TBS varied significantly depending on the core materials and resin cements used [P< 0.05]. The micro TBS of Bifix QM was significantly higher than of Duo-Link in all core materials. The micro TBS of zirconia core was significantly higher than of both composite cores with both resin cements. There were no statistically significant differences among Nulite F and Filtek Z250 [P> 0.05]. The highest bond strength was obtained between zirconia core and Bifix QM [45.3 +/- 6.7 MPa]
Conclusion: in vitro micro TBS of glass ceramic blocks bonded to zirconia core material showed higher bond strength values than resin-based core material, regardless of the resin cement type used
RESUMEN
Objective: Removal of enamel superficial layer during microabrasion treatments may adversely affect sealing ability of the restorative materials. The aim of this study was to measure the effect of different periods of enamel microabrasion on the microleakage of class V glass-ionomer restorations
Methods: This in vitro experimental study was conducted on 96 Class V cavities which had been prepared on the buccal and lingual surfaces of 48 sound human premolars. After conditioning with 10% polyacrylic acid [GC, Tokyo, Japan] one half of the cavities were restored with the conventional glass-ionomer [Fuji II GC, Tokyo, Japan] and another half with resin-modified glassionomer [Fuji II LC GC, Tokyo, Japan]. Finishing and polishing were performed after 24 hours and the teeth incubated for 2 weeks [37[degree sign] and 100% humidity].Then the teeth were classified into eight groups [n=12]. Microabrasion treatment was performed with Opulster [Ultradent product Inc, South Jordan, UT, USA] in 0[control no treatment], 60, 120 and 180 seconds. Then teeth were thermocycled between 5[degree sign]-55[degree sign] [×1000], immersed in 0.5% basic-fushin solution [24h] and sectioned longitudinally in bucco-lingual direction [n=192]. Dye penetration was examined with stereomicroscope [×40]. Microleakage scores were statistically analyzed by Kruskal-Wallis test while the paired comparisons were done using Mann-Whitney U test
Results: The mean microleakage scores were significantly increased following increased microabrasion times in occlusal margin in FU II [p<0.009] and FU II LC [p<0.02] and in gingival margin in resin-modified glass-ionomer [p<0.04]
Conclusion: In Fuji II restorations after microabrasion in occlusal margins, microleakage increased up to 120s but in gingival margins no significant difference were seen. In Fuji II LC restorations after microabrasion in occlusal margin, microleakage from 60s up to 180s was significantly increased. In gingival margin with increasing the time up to 180s microleakage increased
RESUMEN
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.