Objectives: Light irradiation and heat have been used to accelerate the process of tooth bleaching. This study aimed to assess the efficacy of conventional bleaching compared to laser-bleaching using three different wavelengths of diode lasers. Materials and Methods: In this in-vitro experimental study, 40 extracted human central incisors were immersed in a coloring solution made of tea, coffee, and cola for 21 days. The L*, a*, and b* color parameters were measured before and after the immersion using spectrophotometry. The teeth were then randomly divided into four groups (n=10) as follows: group 1: 810-nm diode laser + Biolase Laser White 20, group 2: 940-nm diode laser + Biolase Laser White 20, group 3: 980-nm diode laser + Biolase Laser White 20, and group 4: conventional bleaching with Opalescence Boost without laser irradiation. One-way analysis of variance (ANOVA) was used to assess the effect of laser type and bleaching technique on color parameters. Results: The 940-nm (∆E=28.5896) and 810-nm laser groups (∆E=21.2382) showed the highest and the lowest bleaching efficacy, respectively; however, the groups were not significantly different in terms of bleaching efficacy (P>0.05). Conclusion: Laser-bleaching with 810-, 940- and 980-nm wavelengths of diode laser has an efficacy similar to that of conventional bleaching but in a shorter period. No difference was noted between different laser wavelengths in terms of bleaching efficacy.

Objectives. This study assessed the effect of immersion in acidic solutions and sodium fluoride on surface roughness of dental ceramics. Materials and Methods. 40 blocks of Vitablocs Mark II and IPS e.max CAD (5 × 5 × 3) were prepared. The samples were divided into five groups (n = 8) for immersion in artificial saliva (control), artificially prepared gastric acid, acetic acid, 0.02% sodium fluoride + gastric acid, and 0.02% sodium fluoride + acetic acid. The samples were immersed for 168 hours in the respective solutions except for sodium fluoride, in which the samples were immersed for 69 hours. The surface roughness of samples was measured before and after immersion using a profilometer. The surface roughness changes of three specimens of each group were evaluated by scanning electron microscopy (SEM). Data were analyzed using one-way and two-way ANOVA, Tukey’s test, and independent t-test. Results. Significant changes were noted in Ra ( P = 0.002 ) and Rq ( P < 0.0001 ) in both types of ceramics. The lowest changes in Ra and Rq parameters were seen in artificial saliva and gastric acid and highest changes occurred following immersion in 0.02% sodium fluoride + acetic acid and 0.02% sodium fluoride + gastric acid, respectively. Changes in Rz were also significant following immersion in Vitablocs Mark II ( P < 0.05 ). Immersion in 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid produced a rougher surface on both types of ceramics (SEM). Conclusion. Exposure of Vitablocs Mark II CAD and IPS e.max CAD to 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid significantly increased their surface roughness, while for Vitablocs Mark II, lager defects were seen on its surface.

Aim: This study aimed to assess the efficacy of cavity liners with/without the atmospheric cold plasma jet (ACPJ) for dentin remineralization. Material and methods: The occlusal third of 24 extracted third molars was cut. An occlusal cavity was prepared in the dentin of each tooth with 1 mm depth and 2 mm diameter and demineralized with 37% phosphoric acid for 1 min. The teeth were randomly divided into 8 groups (n ¼ 3). The first control group only underwent demineralization with phosphoric acid. The second control group underwent demineralization and helium plasma jet. Groups 3 to 5 were filled with calcium hydroxide (CH), RetroMTA (MTA) and Biodentine. Groups 6 to 8 were subjected to ACPJ, and all the groups were sealed with polycarboxylate. After 2 weeks of immersion in water, the teeth were longitudinally sectioned and their mineral content was analyzed using energy-dispersive X-ray spectroscopy (EDX). Results: The interaction effect of ACPJ and type of liner was not significant (p > 0.05). Application of ACPJ in combination with liner had a significant effect on calcium and phosphorous contents (p < .05). The calcium and phosphorous contents in the control groups were significantly lower than other groups (p < .05). The calcium and phosphorous contents in the CH group were higher than the control but significantly lower than the MTA and Biodentine groups. The values in the MTA and Biodentine groups were the same and higher than other groups. Conlusion: All three cavity liners significantly increased the calcium and phosphorous contents of dentin. This increase was significantly greater by the MTA and Biodentine and enhanced by the ACPJ.