Microleakage Comparison of Polyacid Composite Resin Restorations and Resin Modified Glass Ionomer Before and After Ultrasonic Scaling

Introduction: In different investigations, the destructive effect of ultrasonic scalers on the margins of composites has been studied, but there are very few studies on the effects of ultrasonic scalers on the microleakage of poly-acid modified composite resin and resin modified glass ionomers. The main purpose of this study was to evaluate the marginal microleakage of class V preparations restored with resin modified glass ionomer and poly-acid modified composite resin before and after scaling with an ultrasonic scaler. Methods: This in vitro study was performed on 160 premolar teeth. Standard class V cavities were prepared on the buccal surfaces of the selected teeth. Occlusal and cervical margins were placed entirely in enamel and cementum, respectively. Teeth were randomly divided to two groups of eighty, each. For one half of each group, (40 teeth) resin modified glass ionomer and for the other half, polyacid modified composite resin was used. Each one of the binary groups was subdivided to two groups. First subgroup was restored with Fuji II Lc (Fuji Japan) and Vitremer (3M USA ) and the second subgroup was restored with F2000 compomer (3M USA) and Compoglass(Vivadent Germany). For bonding to enamel, dentinte,cementum Singlebond (3M USA) and Adhese 2 (Vivadent Germany) were used and all of the restorations were done according to instructions of the manufacturers. In ten teeth of each group, ultrasonic scaling was done and in the other ten teeth, scaling was not done. After that, all of the teeth were thermocycled and immersed in fuschin. After cutting the microleakage was evaluated. The data was analyzed by Mann – Whitney, Kruskal – Wallis and Wilcoxon tests and significant border was 0.05 . Results: The results showed that the degree of microleakage in enamel margins of poly –acid modified resin composites was lower than resin modified glass ionomers and in all groups and subgroups, the microleakage in enamel and cementum after scaling was significantly more than the groups without scaling. Conclusion: Use of resin modified glass ionomers in class V restorations has no advantages over polyacid modified composite resins

In vitro Evaluation of Microleakage of Orthodontic Brackets Bonded Using Methacrylate and Silorane Base Composite

Background: One of the orthodontic treatment problems, which causes marginal gaps and microleakage between tooth and composite is microleakage of composite bonding of orthodontic brackets. The microleakage formation permitting the passage of bacteria and oral fluids, which may cause white spot lesions under the brackets surface area.This is a clinical problem during orthodontic treatment. Few studies have been conducted in this area. The aim of this study was comparison of microleakage of composite silorane base and methacrylate base composite in orthodontic brackets. Methods: Thirty human premolar were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane base composite, in group 2, 15 orthodontic brackets were bonded using methacrylate base composite. Then the teeth were kept in water and thermo cycled(500×, 5-55°C). Specimens were further sealed with nail varnish, stained with 5% basic fuchsin for 24 hours. Then, all teeth sectioned and dye penetration rate were examined by an esteriomicroscope, and scored 0 to 3 for marginal microleakage for the bracket- adhesive and adhesive-enamel interfaces. The data collected analyzed with SPSS16 software, and fisher exact and Mann Whitney tests. Results: Microleakage values were lower in silorane composite than in the methacrylate group, and this difference was found to be statistically significant(P-value =0.03). Also, the rate of microleakage between adhesive-bracket than adhesive-enamel interface was meaningful(P-value=0.025). Conclusions: The results of the current relealed that silorane-bass silorane-base composite provided low microleakage for orthodontic brackets, for this reason, it could be used it for bonding brackets

The Evaluation of Relationship between Self-efficacy in Research and Research Performance of Dental Student, of Yazd Dental College in 2014

Introduction: Achieve to maximum progress and improvement, just depends on addressing targeted research investment and investment of researchers and students. So, the present study was accomplished by the aim of evaluation of the relationship between self-efficacy in research and research performance of dental student of Yazd Dental College in 2014.   Methods: In this cross-sectional study, all interns and assistants in Yazd Dental School were participated. The required data were collected by using the Self-efficacy in Research and Research Performance questionnaire plus demographic variables (age, sex and duration of using denture). The data were analyzed by SPSS ver.16 using ANOVA, T-test and Pearson's correlation coefficient.   Results: In the present study, 80 students with the mean age 27.30±4.67 years were participated. Twenty-two students (27.5%) were males and 58 (72.5%) were females. The overall mean of self-efficacy in research was 159.79 ± 27.69. And the mean of research performance was 11.02 ± 16.37. The results showed that there was a significant and positive relationship between the overall scale of self-efficacy and research (p-value=0.004,r= .03). Based on the age, there was no significant difference in the mean score of self-efficacy in research in all aspects but in the areas of skills and expertise   (p>0.05). There was a significant difference in the mean score of research performance in terms of the age(p-value=0.023). There was no statistical significant between the overall mean score and the score of seven parts of self-efficacy in research and research performance in the terms of sex (P>0.05).   Conclusions: Regarding the association of self-efficacy in research with research performance of dental students, it can be stated that awareness of the level of self efficacy in research can lead to better planning for improving the research performance

Investigating the Effect of C-Factor and the Method of Bulk-Fill and Nanohybrid Composites Placement on Their Microtensile Bond Strength to Dentin

Statement of Problem: Bulk-fill composites have recently been introduced. There are few studies conducted on them. Objectives: Therefore, the aim of this study is to ascertain the effect of C-factor and the method of bulk-fill and nanohybrid composites placement on their microtensile bond strength to dentin. Materials and Method: In this study, 40 extracted third human molars with no caries were collected. The specimens were disinfected and mounted on plaster blocks. Some rectangular cavities (5*3 mm2) were carved on the occlusal level of teeth in the depths of 2 and 4 millimeters. The molars were equally divided into eight study groups at random. After the carving was done, cavities were restored with universal (Tetric N-ceram/Ivoclar vivdent) and bulk-fill (Tetric N-ceram BulkFill/Ivoclar vivdent) composites with incremental and bulky techniques. Then they were stored in distilled water for one week. After that, they were cut into halves from the middle of the restoration spot at the buccolingual direction to turn them into rectangles. Then the microtensile bond strength test was carried out on them to record the failure resistance. The data were analyzed by conducting an ANOVA, a post hoc test, and a T-test. The failure mode was evaluated with a stereomicroscope. Results: Using bulk-fill and nanohybrid composites in cavities filled mas-sively in a 4-mm depth showed a significantly lower level of microtensile bond strength compared with other groups (p= 0.000). Failure was often adhesive in these groups. Conclusion: Considering the research constraints of this laboratory study, bulk-fill composites can be cured well in a 4-mm depth. However, it is advised to use the incremental method in cavities with high C-factors due to the high stress caused by the polymerization shrinkage

‍Prevalence and Comparison of DMFT in 15 Year Old Male High School Students of Yazd City, 2002-2009

Introduction: The purpose of this cross- sectional study was to evaluate the prevalence of dental caries in 15 year old high school students of Yazd. Methods: A total of 295 boy students with mean age of 15 years± 6 month in 2002 and 180 boy students in 2009 were selected randomly and after necessary examination, the obtained data was recorded and evaluated. Results: The over all mean DMFT was 4.8± 3.13 and 11.5% of the subjects(34 cases) were caries free. 4.4% of the population had DMFT> 10 and 6.92% of DMFT was due to extracted teeth. Meanwhile, 77.5% of the DMFT was due to decayed teeth. Also, the percentage of teeth with fillings was 15.53%. Of the total, 93.08% had all the teeth present in their mouth that is a little higher than the 2000 WHO criteria which is 85%. Conclusion: Preventive and therapeutic dentistry services in Yazd city are far from the standard levels and therefore the results of this study could be utilized for systematic planning of preventive and therapeutic affairs