Effect of Ozonated Water on the Color Stability of Denture Teeth and Heat Polymerized Acrylic Base Resin

Objective: To determine the effect of ozonated water on the color stability of denture tooth and denture bases. Material and Methods: Thirty denture base discs consisting of 15 Acropars and 15 ProBase Hot specimens with the dimensions of 40 × 5 mm were prepared. Fifteen denture teeth in shade A1 (Ivoclar Vivadent, Schaan, Liechtenstein) were mounted in a specific acrylic jig. All specimens were immersed in three solutions (1% sodium hypochlorite, ozonated water, and distilled water) for four months (one year of clinical use). Color measurements were done with a spectrophotometer and assessed using the CIE L*a*b* colorimetric system (0, 4, 8, 12, and 16 weeks). Data were analyzed using the three-way ANOVA and Tukey test ( α =0.05). Results: Tukey's post hoc test revealed a significant change in color in the Acropars denture base for the distilled water group compared to the ozonated water and 1% hypochlorite (p<0.05). Regarding the ProBase Hot denture base, significantly less color change was observed in the 1% hypochlorite group compared to the ozonated water and distilled water (p≤0.001). For the denture teeth, significantly less color change was seen in the distilled water group than in the ozonated water (p=0.015) and 1% hypochlorite (p<0.05) groups. Conclusion: The color change of denture bases and denture tooth in ozonated water are acceptable. Ozonated water can be considered a good disinfectant for cleaning dentures

Antimicrobial Activity of Colloidal Selenium Nanoparticles in Chitosan Solution against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans

Objective: To investigate the antimicrobial activity of colloidal selenium nanoparticles in chitosan solution (Cts-Se-NPs) against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Material and Methods: Cts-Se-NPs solution was prepared using a simple chemical reduction method. The MIC and MBC against S. mutans, L. acidophilus, and C. albicans were determined using the broth dilution assay. Results: The Cts-Se-NPs had remarkable antimicrobial activity against S. mutans, L. acidophilus, and C. albicans. The MIC values of the Cts-Se-NPs were lowest for S. mutans (0.068 mg/ml) compared to L. acidophilus (0.137 mg/ml), and C. albicans (0.274 mg/ml). The MBC values of the Cts-Se-NPs against the microorganisms after one, two, six, and 24 hours indicated that the concentration of 0.274 mg/ml of Cts-Se-NPs completely killed S. mutans, L. acidophilus, and C. albicans after one, two, and six hours, respectively. At the concentration of 0.137 mg/ml, S. mutans and L. acidophilus were killed after six and 24 hours, respectively. Conclusion: These findings encourage the potential use of Cts-Se-NPs in dentistry, while further clinical research is required in this area

Comparison of the High Cycle Fatigue Behavior of the Orthodontic NiTi Wires: An in Vitro Study

Objective: To compare the high-cycle fatigue behavior of four commercially available NiTi orthodontic wires. Material and Methods: Twelve NiTi orthodontic wires, round, 0.016-in, three per brand, were selected and divided into four groups: G1 - Heat-activated NiTi, G2 - Superelastic NiTi, G3 - Therma-Ti, and G4 - CopperNiTi. The atomic absorption spectrometry method was used to determine the chemical composition of investigated NiTi wires. We also performed a fatigue test at three-point bending using a universal testing machine for 1000 cycles in a 35 °C water bath. For the first and thousandth cycle, the average plateau load and the plateau length were determined in the unloading area of the force versus displacement diagram. In addition, we calculated the difference between the average plateau load of the first and thousandth cycle (∆F), as well as the difference between the plateau length of both cases (∆L). Results: According to our results, there were no significant differences between the average plateau load of the first and thousandth cycles of each group (p>0.05) and in the plateau length of the first and thousandth cycles of the groups (p>0.05). Conclusion: There were no significant differences between the groups changing the superelasticity property after high-cycle fatigue

Effect of ibuprofen and low-intensity pulsed ultrasound on the reduction of pain after initial archwire placement: a double-blind randomized clinical trial

Objective: This study aimed to compare the effect of ibuprofen and low-intensity pulsed ultrasound (LIPUS) on the reduction of pain after the placement of initial archwire in orthodontic patients. Material and Methods: This double-blind clinical trial study was carried out on 60 female candidates for fixed orthodontic treatment referring to the Orthodontic Department of School of Dentistry in Mashhad University of Medical Sciences, Mashhad, Iran, during 2015-2016. The subjects were divided into four groups of ibuprofen, LIPUS, placebo, and mock LIPUS. A questionnaire and a rectangular and flexible cubic silicone were given to each patient to record the severity of pain based on the visual analog scale at specified time points (i.e., 2 h, 6 h, at bedtime, 2nd, 3rd, and 7th days after archwire placement) when biting the silicone block with the anterior and posterior teeth and without biting at all. Repeated measures analysis of variance was used in order to compare the pain severity at different time points. Results: The comparison of pain severity at various time points showed that the highest and lowest mean scores of pain were reported at bedtime and seven days after the intervention (p0.05). Conclusion: In conclusion, LIPUS (with a frequency of 1 MHz and an intensity of 100 mW) and ibuprofen have no significant effects on reduction of the pain severity at different time points and various conditions in orthodontic patients

Effect of the Time of Salivary Contamination during Light Curing on Degree of Conversion and Microhardness of a Restorative Composite Resin

Saliva contamination is a major clinical problem in restorative procedures. The purpose of this study was to evaluate the effect of the time of salivary contamination during light curing on the degree of conversion and the microhardness of a restorative composite resin. Eight groups of 10 samples for measuring the microhardness and eight groups of 5 samples for evaluating the degree of conversion were prepared. The samples of each group were contaminated with human saliva at a certain time. The first group (T0) was contaminated before light curing. The specimens in groups T2–T30 were contaminated at 2, 5, 10, 15, 20 and 30 s after the start of light curing, respectively. The samples of group T40 were contaminated after light curing. The degree of conversion and the microhardness of the specimens were measured by Fourier transform infrared (FTIR) spectroscopy and Vickers hardness testing techniques, respectively. The results of this study revealed that there were no significant differences between the groups in terms of the degree of conversion of the composite resin. Consistent with the findings for the degree of conversion, significant differences in the microhardness between the groups were not found. In conclusion, from a clinical point of view, the results of our study showed that the time of salivary contamination (before, during or after light curing of composite resin) has no significant effect on the polymerization (degree of conversion) and one of the important mechanical properties of dental composite resins (microhardness)

Effects of Magnesium Oxide Nanoparticles Incorporation on Shear Bond Strength and Antibacterial Activity of an Orthodontic Composite: An In Vitro Study

This study aimed to evaluate the effects of magnesium oxide (MgO) nanoparticle (NP) incorporation on shear bond strength (SBS) and antibacterial property of orthodontic composites. A total of 100 mounted premolar teeth were randomly divided into five groups. In group 1 (control), the brackets were bonded to the teeth using the GC Ortho Connect orthodontic composite, while the brackets of groups 2 to 5 were bonded by the GC Ortho Connect orthodontic composite that contained 0.5%, 1%, 2%, and 4% weight percentages (w/w) of MgO NPs, respectively and then the SBS was measured. In the following, we evaluated the antibacterial properties of the MgO NP-containing composite on Streptococcus mutans (S. mutans) bacteria by the direct contact test method. According to results, there were no significant changes in the SBS as the MgO NP concentration was increased up to 1%, while the SBSs of the 2% and 4% MgO NPs were decreased when compared to the other three groups. The outcomes of the direct contact test indicated the case of 1% as being the minimum ratio of MgO NPs, which almost caused the entire annihilation of the S. mutans bacteria. In conclusion, the orthodontic composite containing 1% MgO NPs can display a significant antibacterial effect against S. mutans bacteria without inducing any negative effect on the SBS

Effects of Adding Cinnamon, ZnO, and CuO Nanoparticles on the Antibacterial Properties of a Glass Ionomer Cement as the Luting Agent for Orthodontic Bands and Their Cytotoxicity

This study was conducted to evaluate the effects of adding cinnamon nanoparticles (NPs), Zinc oxide (ZnO) nanoparticles (NPs), and Copper oxide (CuO) NPs on the antibacterial property of a luting and lining glass ionomer cement (GIC) that was used for the cementation of orthodontic bands to the tooth. Cinnamon NPs, ZnO NPs, and CuO NPs were added into a luting and lining GIC in weight percentages of 1%, 2%, and 4%, respectively while a non-modified GIC was considered as the control group. Agar disc diffusion test was applied to assess the antimicrobial property of samples against Streptococcus mutans (S. mutans). The cytotoxicity of the nanoparticles was examined through the MTT assay for gingival fibroblasts. Data showed that GIC containing cinnamon and ZnO NPs displayed a larger inhibition zone diameter and greater antibacterial activity against S. mutans than CuO NPs. Meanwhile, there were no significant differences in the inhibition zone diameter of cinnamon NPs and ZnO NPs. The cytotoxicity assessment revealed the lower cytotoxicity of cinnamon NPs and the higher cytotoxicity of CuO NPs while the cytotoxicity of ZnO NPs was observed to be higher than cinnamon NPs and lower than CuO NPs. GIC containing cinnamon NPs exhibited noticeable antibacterial activity against S. mutans and cinnamon NPs revealed less cytotoxicity and it is can be labeled as a favorable option for further assessment to be applied in fixed orthodontic treatments for the cementation of bands to teeth

An In Vitro Study on the Effect of Amorphous Calcium Phosphate and Fluoride Solutions on Color Improvement of White Spot Lesions

The ability of remineralizing agents to improve the color of white spot lesions (WSL) is an important aspect that should be investigated. The aim of this study was to evaluate the effects of 0.05% amorphous calcium phosphate (ACP), 0.5% ACP, and 0.05% fluoride solutions, as well as artificial saliva on the color improvement of white spot lesions (WSLs). In this in vitro study, 50 human premolar teeth were randomly classified into five groups. At baseline, all the samples were assessed by using a colorimeter (E0). Then, white spot lesions were induced on the surface of the teeth by means of a pH-cycling model, and the colorimeter was used again (E1). Afterwards, samples of the 1st and 2nd groups were kept in 0.05% ACP and 0.5% ACP solutions for 1 min/day, respectively. The 3rd group specimens were placed in 0.05% fluoride solution for 1 min/day. The other two groups were kept in artificial saliva and distilled in water separately. All the samples were assessed by the colorimeter for a third time (E2). We found no significant difference between the groups in ∆E1. There was also no significant difference among 0.05% ACP solution, 0.5% ACP solution, 0.05% fluoride solution, and artificial saliva considering ∆E2. However, a significant difference was noted between the above-mentioned solutions and distilled water in ∆E2. With respect to ∆E3, there were considerable differences between ACP solution and artificial saliva. The same results were obtained for the difference between fluoride solution and artificial saliva. However, no significant difference was found among 0.05% ACP, 0.5% ACP, and 0.05% fluoride solutions in terms of ∆E3. In Conclusion, ACP is as effective as fluoride in the color improvement of WSLs and the recommended treatment for this purpose is daily use of 0.05% ACP, 0.5% ACP or 0.05% fluoride solutions

Effects of Adding Cinnamon, ZnO, and CuO Nanoparticles on the Antibacterial Properties of a Glass Ionomer Cement as the Luting Agent for Orthodontic Bands and Their Cytotoxicity

This study was conducted to evaluate the effects of adding cinnamon nanoparticles (NPs), Zinc oxide (ZnO) nanoparticles (NPs), and Copper oxide (CuO) NPs on the antibacterial property of a luting and lining glass ionomer cement (GIC) that was used for the cementation of orthodontic bands to the tooth. Cinnamon NPs, ZnO NPs, and CuO NPs were added into a luting and lining GIC in weight percentages of 1%, 2%, and 4%, respectively while a non-modified GIC was considered as the control group. Agar disc diffusion test was applied to assess the antimicrobial property of samples against Streptococcus mutans (S. mutans). The cytotoxicity of the nanoparticles was examined through the MTT assay for gingival fibroblasts. Data showed that GIC containing cinnamon and ZnO NPs displayed a larger inhibition zone diameter and greater antibacterial activity against S. mutans than CuO NPs. Meanwhile, there were no significant differences in the inhibition zone diameter of cinnamon NPs and ZnO NPs. The cytotoxicity assessment revealed the lower cytotoxicity of cinnamon NPs and the higher cytotoxicity of CuO NPs while the cytotoxicity of ZnO NPs was observed to be higher than cinnamon NPs and lower than CuO NPs. GIC containing cinnamon NPs exhibited noticeable antibacterial activity against S. mutans and cinnamon NPs revealed less cytotoxicity and it is can be labeled as a favorable option for further assessment to be applied in fixed orthodontic treatments for the cementation of bands to teeth

Evaluation of the Relationship Between Morphology, Volume, and Density of the Mandible and Dentofacial Vertical Dimension Using Cone Beam Computed Tomography

Objective:To evaluate the relationship between mandibular shape, mandibular bone density, cortical bone thickness, and condylar volume and facial height using a cone-beam computed tomography (CBCT). Material and Methods:Fifteen female patients (16-25 years old) were included in this study. The following measurements were performed on CBCT radiographs; inter-canine and inter-molar width of the mandible at three vertical points (alveolar crest, apex and basal bone), mandibular cortical bone thickness in disto molar and canine sections, bone density of the mandibular body and condylar volume. Afterward, subjects were divided into short face, normal and long face groups according to the Frankfort-mandibular plane angle (FMA) measured on lateral cephalograms obtained from CBCTs. Data were analyzed using Pearson correlation, one-way ANOVA, and post-hoc analysis. Results:The inter-canine width of the mandible at the apical point in long face subjects was greater than in the other groups. Likewise, the cortical bone thickness was significantly higher in long face patients compared to the short face and normal subjects. There was no statistically significant difference in mandibular density or condylar volume between patients with various vertical heights (p>0.1). Conclusion:Vertical growth pattern is correlated with mandibular morphology to some extent