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

Abstract 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.

Effect of ibuprofen and low-intensity pulsed ultrasound on the reduction of pain after initial archwire placement: a double-blind randomized clinical trial / Efecto del ibuprofeno y el ultrasonido pulsado de baja intensidad en la reducción del dolor después de la colocación inicial del arco de ortodoncia: un ensayo clínico aleatorizado doble ciego

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 (p<0.001). In each of the three conditions (i.e., biting the silicone block with the anterior and posterior teeth and without biting the teeth) at six time points (i.e., 2 h, 6 h, at bedtime, 2nd, 3rd, and 7th days following archwire placement), no significant difference was observed in the severity of pain (p>0.05). 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.

Objetivo: Este estudio tuvo como objetivo comparar el efecto del ibuprofeno y el ultrasonido pulsado de baja intensidad (LIPUS) en la reducción del dolor después de la colocación del arco inicial en pacientes de ortodoncia. Material y Métodos: Este estudio de ensayo clínico doble ciego se llevó a cabo en 60 candidatas a tratamiento de ortodoncia fija referidas al Departamento de Ortodoncia de la Facultad de Odontología de la Universidad de Ciencias Médicas de Mashhad, Mashhad, Irán, durante 2015-2016. Los sujetos se dividieron en cuatro grupos: ibuprofeno, LIPUS, placebo y LIPUS simulado. Se entregó un cuestionario y un bloque de silicona cúbica rectangular y flexible a cada paciente para registrar la intensidad del dolor según la escala analógica visual en puntos de tiempo específicos (es decir, 2 h, 6 h, hora de acostarse, 2do, 3er y 7mo día después de la colocación del arco) al morder el bloque de silicona con los dientes anteriores y posteriores, y sin morder en absoluto. Se utilizó el análisis de varianza de medidas repetidas para comparar la intensidad del dolor en diferentes momentos.Resultados: La comparación de la intensidad del dolor en varios puntos de tiempo mostró que las puntuaciones medias de dolor más altas y más bajas se informaron a la hora de acostarse y siete días después de la intervención (p<0,001). En cada una de las tres condiciones (es decir, al morder el bloque de silicona con los dientes anteriores y posteriores, y sin morder) en seis momentos (2 h, 6 h, antes de acostarse 2do, 3er y 7mo día después de la colocación del arco), no se observó diferencia significativa en la severidad del dolor (p>0.05).Conclusión: En conclusión, LIPUS (con una frecuencia de 1 MHz y una intensidad de 100 mW) y el ibuprofeno no tienen efectos significativos en la reducción de la severidad del dolor en diferentes puntos de tiempo y diversas condiciones en pacientes de ortodoncia.

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

Abstract 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.

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

ABSTRACT 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.

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

Abstract 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.