Cytotoxicity and Antibacterial Activity of Toothpastes and Mouthwashes Available in the Iranian Market.

Objectives: Toothpastes and mouthwashes contain chemicals that may be harmful to oral tissues. This study assessed the cytotoxicity and antibacterial activity of toothpastes and compare the Iranian and foreign toothpastes and mouthwashes available in the Iranian market in this respect. Materials and Methods: Twenty samples (13 toothpastes and 4 mouthwashes) were selected. The cytotoxicity of 1, 10, and 50 mg/mL of toothpastes and 0.05, 2 and 10 µL of mouthwashes was measured after 1, 15 and 30 min of exposure to human gingival fibroblasts, each in triplicate. The methyl thiazolyl tetrazolium (MTT) assay was used for cytotoxicity testing. The serial dilution method was utilized to determine the minimum inhibitory concentration (MIC) of each sample against Lactobacillus acidophilus (L. acidophilus) and Streptococcus mutans (S. mutans). Two-way ANOVA and Tukey's test were used for data analysis. Results: A significant difference in cytotoxicity was noted among different products (P=0.00). The difference in cytotoxicity of each sample was not significant at 1, 15 and 30 min (P=0.08). The obtained MIC for all toothpastes and mouthwashes was between 0.0039 mg/mL and 0.0156 mg/mL, except for Sensodyne toothpaste and Oral B mouthwash. Conclusion: Some brands of toothpastes have higher cytotoxicity due to their composition, and their cytotoxicity should not be overlooked. The antibacterial activity of the samples was almost equal when they were in contact with L. acidophilus and S. mutans except for the Irsha mouthwash, Sehat, Darugar and Bath toothpastes. The antibacterial effect of toothpastes and mouthwashes increased with an increase in exposure time.

Evaluation of the Effects of 810 nm Diode Laser Alone and in Combination With Gluma© and Chromophore on Dentinal Tubule Occlusion: A Scanning Electron Microscopic Analysis.

Introduction: Tooth hypersensitivity is among the most common patient complaints caused by the response of exposed dentin to external stimuli. No definite treatment has been suggested so far for dentin hypersensitivity (DH). This study aimed to compare the efficacy of the diode laser alone and in combination with Gluma and chromophore in occluding opened dentine tubules and the treatment of DH. Methods: This in vitro study was conducted on 30 extracted human third molars kept in 0.1% thymol solution. The teeth were mounted in transparent acrylic resin and the buccal enamel was cut to expose the outer third of dentin. The samples were then divided into 6 groups of negative control (no smear layer removal), positive control (smear layer removal with 6% citric acid application), 810 nm diode laser irradiation (energy density 55.55 J/cm2 , 1 W for 20 seconds in a continuous mode), chromophore (1 mg/mL indocyanine green, ICG) plus diode laser irradiation (1 W, 20 seconds), Gluma plus diode laser irradiation, and Gluma + chromophore + diode laser. Dentinal tubules were evaluated under a scanning electron microscope at x2000 magnification. The mean percentage of the obstruction of dentinal tubules was reported as mean and standard deviation. Considering the normal distribution of the data, two-way ANOVA was applied to compare the efficacy of treatments, and an independent-samples t test was used for pairwise comparisons at P<0.05 level of significance. Results: The highest mean percentage of the obstruction of dentinal tubules was noted in the diode laser/chromophore/Gluma group (65.68±12.31%) while the lowest value was noted in the diode laser/Gluma group (24.33±5.90%). Pairwise comparisons revealed significant differences between all groups (P <0.05) except for the difference between the laser/Gluma/chromophore and laser/ chromophore groups (P =0.20). Conclusion: It seems that chromophore increases the efficacy of the diode laser for the obstruction of dentinal tubules.

Comparison of Dentin Permeability After Tooth Cavity Preparation with Diamond Bur and Er:YAG Laser.

OBJECTIVES: The aim of this study was to compare the permeability of dentin after using diamond bur and Er:YAG laser. MATERIALS AND METHODS: Seventy-two recently extracted, intact, and restoration-free human permanent molars were used in this study. The samples were randomly divided into three groups of 24 each and class I cavities were prepared as follows. Group 1: High speed diamond bur with air and water spray. Group 2: Er:YAG laser. Group 3: Er:YAG laser followed by additional sub-ablative laser treatment. Each group consisted of two subgroups with different cavity depths of 2mm and 4mm. The entire cavity floor was in dentin. Two samples from each subgroup were observed under scanning electron microscope (SEM). The external surfaces of other samples were covered with nail varnish (except the prepared cavity) and immersed in 0.5% methylene blue solution for 48 hours. After irrigation of samples with water, they were sectioned in bucco-lingual direction. Then, the samples were evaluated under a stereomicroscope at ×160 magnification. The data were analyzed using two-way ANOVA and Tukey's HSD test. RESULTS: Two-way ANOVA showed significant difference in permeability between groups 2 and 3 (laser groups with and without further treatment) and group 1 (bur group). The highest permeability was seen in the group 1. There was no significant difference in dentin permeability between groups 2 and 3 and no significant difference was observed between different depths (2mm and 4mm). CONCLUSION: Cavities prepared by laser have less dentin permeability than cavities prepared by diamond bur.

Effect of In-Office Carbamide Peroxide-Based Tooth Bleaching System on Wear Resistance of Silorane-Based and Methacrylate-Based Dental Composites.

OBJECTIVES: Several studies have assessed the characteristics and properties of silorane-based composites and adhesive systems. Considering the extensive application of tooth-whitening agents, possible deteriorative effects of tooth bleaching agents on these restorative materials must be studied. The aim of this study was to evaluate the effect of an in-office carbamide peroxide-based tooth bleaching agent on the wear resistance of a silorane-based and a conventional microhybrid dimethyl methacrylate-based dental composite with two different application times. MATERIALS AND METHODS: Thirty cylindrical specimens were made of Z250 and P90 dental composite resins (n=15 for each composite). Samples made of each composite were divided into three groups (n=5) for immersion in an in-office bleaching agent (Opalescence® Quick 45%) for either three or eight hours or saline solution (control). Wear tests were conducted after bleaching using a pin-on disk apparatus under the load of 40N at a constant sliding speed of 0.5 ms(-1) for a sliding distance of 300 m. The samples were weighed before and after the wear test. Repeated measures ANOVA was used to statistically analyze the obtained data (α=0.05). RESULTS: There was a significant decrease in the weight of samples after the wear test (P<0.001). However, no significant difference was found among groups in the mean weight of samples before and after the wear test (P>0.05). CONCLUSION: Bleaching for three or eight hours using 45% carbamide peroxide had no deteriorative effect on the wear resistance of Z250 and P90 composites.

Shear bond strength of the repair composite resin to zirconia ceramic by different surface treatment.

INTRODUCTION: The purpose of this study is the evaluation of the amount of surface roughness (Ra) of Zirconia Ceramic following different surface treatments as well as the assessment of its shear bond strength to composite resin. METHODS: 40 sintered zirconia ceramic block samples were randomly divided in 4 groups of 10 and underwent the following surface treatments: a) Control group without treatment b) Air abrasion with Al2O3 particles (50um) c) Er:YAG laser with 2W power for 10s d) Nd:YAG laser with 1.5W power for 2min Then the mean surface roughness (Ra) was evaluated by profilometer. In the next step, Alloy primer was used on a section of 9mm(2) on the samples following the manufacturer's instructions. After that Clearfil AP-X composite resin in cylinder shape with an internal diameter and height of 3mm were cured on the sections mentioned. At the end, all samples were tested to assess the shear bond strength by the Universal Testing Machine at a speed of 0.5mm/min until fracture occurred. The mean shear bond strengths were calculated and statistically analyzed by One Way ANOVA. RESULTS: ANOVA analysis showed that roughness (Ra) was significantly different between the groups (P≤0.05). Ra was higher in the Nd:YAG group compared to the other groups (P≤0.05). The lower Ra was related to the control group. Air abrasion group showed highest amounts of shear bond strength and Nd:YAG laser group demonstrated lower amounts of shear bond strength (P≤0.05). CONCLUSION: Various surface treatments are differently effective on bond strength. Air abrasion is the most effective method to condition zirconia ceramic surfaces.