Journal of Dental Medicine
Year:2017 | Volume:30 | Issue:3 |Papers Count:11

Background and Aims: The aim of this study was to evaluate the effects of two fluoride containing mouth rinses on the color stability of two different resin composites. Materials and Methods: 27 specimens (2×4×5 mm) were prepared from each of the following materials: a micro filled composite (Gradia, GC) and nanohybrid (Grandio). The specimens were polished by Soflex fine and superfine disks and then incubated in artificial saliva at 37° C for 24 h. The baseline color values (L, a, b) of each specimen were measured using an Easyshade spectrophotometer according to the CIELab color scale. The specimens were immersed in 20 mL of each mouth rinse and stored in an incubator at 37° C for 12 h. After incubation, the color values of all specimens were measured again, and the color change value (Δ E) was calculated. Data were analyzed by a 2-way analysis of variance at a significance level of 0. 05. Results: None of the mouth rinses created clinical significant color changes in the samples. There was no statistically significant difference among color susceptibility between resin composites (P=0. 330). The interaction between the effect of mouth rinses and type of restorative materials was not statistically significant (P>0. 05). Conclusion: Accordance to the results of this study, the fluoride containing mouth rinses does not create color change in resin composites.

Background and Aims: The aim of this study was to assess the microhardness of BioMTA (OrthoMTA, RetroMTA) in distances of 0. 5, 2 and 3. 5 mm from the exposed surface to blood, phosphate buffer saline (PBS) or distilled water and to compare to that of ProRoot MTA. Materials and Methods: One hundred and thirty five semicylindrical polymethyl methacrylate were filled with either ProRoot MTA, OrthoMTA, or RetroMTA. Fifteen molds in each group were exposed to blood, 15 molds to PBS and the other 15 to distilled water. The microhardness of the materials at 0. 5, 2 and 3. 5 mm distance from the exposed surface to phosphate-buffered saline (PBS) as a synthetic tissue fluid, blood, and distilled water was assessed. The data were analyzed using one-way ANOVA and Tukey post hoc tests. Results: Exposure to blood significantly decreased the microhardness of all materials at all three points of 0. 5, 2 and 3. 5 mm (P<0. 001). At level of 0. 5 and 2 mm distant from blood, OrthoMTA showed significantly the least microhardness value; however, at the point of 3. 5 mm, the microhardness of RetroMTA was higher than the two other materials (P<0. 001). After exposure of samples to distilled water or PBS, no significant difference was found between the materials at any levels of 0. 5, 2, and 3. 5 mm (P<0. 01). Conclusion: Blood exposure resulted in the decrease of microhardness of internal part of the materials.

Background and Aims: One of the main disadvantages of light cured composite resin materials is polymerization shrinkage upon curing. This leads to the microleakage of restoration and finally failure of the restoration. The purpose of this study was to investigate the effect of two types of light curing devices with different modes on the microleakage of posterior composite filling in Cl II restorations. Materials and Methods: In this experimental study, 30 extracted sound molar human teeth were collected. All specimens were randomly divided into 3 groups of ten: Standard LED irradiation, pulse curing LED irradiation and QTH irradiation. All samples were prepared with mesial and distal boxes and composite fillings were done with three different light curing patterns for 20 s. After thermocycling, the specimens were kept in 2% methylene Blue solution for 24 h for microleakage test. After sectioning, the samples were evaluated by a stereomicroscope. For data analysis one-way ANOVA and Kolmogorov-Smirnov were used. P<0. 05 was considered statistically significant. Results: The quantitative tests showed that there were no statistical difference between study groups (P>0. 05). Conclusion: The results showed that both light curing devices were effective and no significant difference between different modes of LED light curing device on microleakage of class II composite restorations was found.

Background and Aims: The purpose of this study was to evaluate the sealing ability of MTA and cold ceramic by using bacterial leakage method. Materials and Methods: In this experimental study, fifty human single root extracted teeth were chosen. In group A, 20 teeth were filled with MTA and in group B, 20 teeth were filled with cold ceramic. Five teeth were used as a positive control (obturated using gutta-percha without sealer), and five teeth were used as negative control (obturated using gutta-percha with AH26 sealer and coated with two layers of nail varnish). A bacterial leakage model utilizing Enterococcus faecalis was used for evaluation of the sealing ability. The teeth were placed in test tubes, so that they formed two upper and lower compartments. The cultured bacteria in the upper chamber were in contact with the coronal area of the tooth. The root end was placed in the lower chamber containing sterile culture media. In this case, the filling of the root canal was only the communication path between the upper and lower chambers. In this method, the presence of turbidity in the lower chamber indicated that bacteria had penetrated through barrier and reached the medium. The leakage was measured. The acquired data was analyzed using Chi-square test. Results: In group A (MTA), 7 samples and in group B (Cold ceramic), 4 samples should the leakage. In regarding the leakage, there was no statistically significant difference between MTA and cold ceramic. (P=0. 288) Conclusion: The results showed that the sealing ability of MTA and cold ceramic was similar as root filling materials.

Background and Aims: To create a good adhesion between porcelain veneers and zirconia restorations has been important issues is the prosthesis. The aim of this study was to identify an effective way to prepare the zirconia surface infrastructure to increase its shear bond strength to the porcelain veneer. Materials and Methods: 75 samples of zirconia (Y-TZP) cylinders (diameter of 7 mm and a thickness of 3 mm) were fabricated. Based on the surface treatment, specimens were randomly divided into 3 groups: control, air abrasion and Er-YAG laser. After surface treatment, the specimen surfaces were examined by SEM. Using a metal mold, the porcelain was veneered on the zirconia surface and then fired. After thermocycling, the shear bond strength of porcelain to zirconia was measured and then the failure mode of each specimen was analyzed using a stereo-microscope. Data were analyzed by one-way ANOVA and Tukey test. Results: Significant differences were observed between the mean shear bond strength of different groups (P=0. 001). The greatest amount of shear bond strength was observed in the group (S) and the lowest bond strength in the control group. Analysis of failure modes showed no statistically significant difference in the type of failure among study groups. The adhesive failure was predominating failure at the intersection of porcelain veneers. Conclusion: The highest shear bond strength between zirconia and porcelain was achieved by sandblasting the zirconia surfaces compare with that of Er_YAG application.

Background and Aims: Poor adhesion between porcelain and some of the dental alloys is one of the most challenges to select the desirable alloy in dental restorations. Therefore, the aim of this study was to evaluate the bond strength of porcelain to some of the commercial alloys. This can help in selection of desirable alloy. Materials and Methods: The shear bond strength of porcelain to the three of the most widely used nickel-base dental alloys commercially named as: Verabond, Damcast and Noritake were evaluated according to standard ASTM E4. The results were analyzed based on the statistical method of independent t with the meaningful level of P<0. 05. Then, the bonding interface of the fired samples was evaluated using SEM equipped with EDX analyzer and X-ray diffractometry. Results: The average bonding strength of porcelain to each of the above mentioned alloys were determined as: 27. 54± 5. 48, 22. 46± 4. 99 and 26. 18± 4. 27 MPa, respectively. Due to the existence of Be and Al in the chemical composition of Verabond and Damcast and their higher appetencies to form the different surface oxides in preference to Cr2O3, not only the bond strength of porcelain to two these alloys was increased about 20 percent (compared with the Noritake), but also the color of their porcelain was not changed. Conclusion: To replace the replacing of deleterious elements from the chemical composition of dental alloys. The added new elements should control through the oxide layer and the formation of Cr2O3 in porcelain-alloy interfaces for adequate bond strength.

Background and Aims: Headache is among the most common complaints in patients suffering from temporomandibular joint disorders (TMD). Thus, it seems that evaluation of patients with headache in terms of temporomandibular joint (TMJ) disorders is necessary. In people with TMD, parafunctional activities play an important etiologic role. Considering the high prevalence of bruxism and TMDs in patients with headache, assessment the accuracy and severity of this association can play a key role in diagnosis and treatment of these two phenomena. The purpose of this study was to investigate the relationship between bruxism, TMD and headache, also assessment the efficacy of TMD conservative therapy with a special approach to self-management in treating patients with headache. Materials and Methods: Motor searches of Cochrane, Medline and EMbase databases, PubMed, Google Scholar, Uptodate, BMJ clinical Evidence, MD consult and science direct by using of relevant key words were searched for article published between 2000 and 2015. A total of English language abstracts were reviewed, 80 full articles were obtained and among them, 30 relevant articles were reviewed in this study. Because of the high number of studies in this field, we divided the data into four group, bruxism and TMD, TMD and headache, bruxism, TMD and headache, treatment. Conclusion: Bruxism and temporomandibular disorders are the two main contributing factors in initiation and perpetuation of headache. Treatment of these two phenomena would be effective in the treatment of headache.

Background and Aims: Radiopacity is an essential requirement for all restorative materials. Radiopaque materials allow the dentist to diagnose and assess radiographically the restoration, primary caries, assessment of contours, overhang and secondary caries. The aim of this study was to evaluate the radiopacity of two types of dental bases and liners in comparison whit dental structure using a digital radiography system. Materials and Methods: Two classes of materials were prepared: 1 mm and 2 mm thickness disks for glass inomer and 1 mm and 0. 5 mm thicknesses for dycal. Specimens of enamel and dentine with the same thicknesses were obtained. As a control, an aluminum step wedge was used. Samples were positioned over a phosphor-ray, plate of min ray soredex system, exposed, and the images were analyzed using the contour dent software. ANOVA analysis was used to investigate the significance of differences among the groups. For pairwise comparisons, the Bonferroni test was applied (P<0. 005). Results: 0. 5 mm diameter of self-cure and light cure dycal and enamel, presented radio-opacity higher than that of dentine, except for the light cure dycal that had radiopacity lowers than enamel. 1 mm diameter of all the groups presented higher radiopacity than dentin. Light cure and self-cure glass inomer and self-cure dycal presented radiopacity higher than enamel. Enamel showed radipacity higher than light cure dycal in 2 mm diameter self-cure. Light cure glass inomer presented radiopacity higher than that of enamel and dentin. Conclusion: The increased thickness of the materials evaluated increased their radio-opacity. It was concluded that all the materials had lower radiopaaty than dentin. Only enamel showed higher radiopacity than light-cured dycal.