Evaluation of the Effects of Different Types of Resin Cement Systems on the Push-Out Bond Strength of the Fiber Post to Intracanal Dentin in Anterior Primary Teeth.

Background: This study aimed to evaluate the effects of using three different resin cements on push-out bond strength (PBS) of fiber posts to root canal dentin of primary teeth. Methods: Fifty primary canines were randomly divided into five experimental groups according to the type of the luting agent used for fiber post cementation after endodontic treatment and post space preparation as the following: Group 1: glass ionomer cement (GIC), Group 2: flowable resin composite, Group 3: etch and rinse (E&R) resin cement, Group 4: self-etch (SE) resin cement, Group 5: self-adhesive (SA) resin cement. The PBS values of the cemented fiber posts to root canals were measured. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's post hoc test. Results: The highest mean PBS value was observed in Group 4 (SE resin cement), followed by Group 3 (E&R resin cement), and the lowest PBS value belonged to Group 1 (GIC), followed by Group 5 (p-values < 0.05). The mean PBS of Group 3 (E&R resin cement) was significantly higher than those of Groups 1 (GIC), 2 (flowable resin composite), and 5 (SA resin cement) (p-values < 0.05). However, no significant difference was found between the mean PBS of GIC and SA resin cement (p-value >0/05). Conclusion: Using SE resin cement for fiber post cementation in primary anterior teeth showed the best results, followed by E&R resin cement. The lowest PBS was observed for GIC, followed by SA resin cement.

The antimicrobial effects of zinc oxide-calcium hydroxide mixture fillers: determining the ideal mixture ratio.

BACKGROUND AND OBJECTIVES: Although zinc oxide (ZO)-calcium hydroxide (CaOH) mixtures have been successful regarding their absorption rate compatibility with dissolving primary teeth, no study has been conducted on the appropriate mixture ratio to obtain effective antibacterial properties. In this study, we compared antibacterial activity of CaOH-ZO pastes using different mixture ratios sagainst Enterococcus faecalis as an important bacterium in root canal treatment failure. MATERIALS AND METHODS: Seven types of pastes were prepared in our laboratory. The first group included one gram of ZO+eugenol, second group included one gram of CaOH+distilled water, third group included 0.5gram ZO+0.5gram CaOH+distilled water (1:1), forth group included 0.75gramCaOH+0.25gramZO+distilled water (3:1), the fifth group included 0.33gram of CaOH+0.66gram of ZO+distilled water (1:2), the sixth group included 0.75gram of ZO+0.25 CaOH+distilled water (3:1), the seventh group included 0.66 gram CaOH+0.33 gram ZO+distilled water (2:1), and the final group included one gram of gelatin+distilled water (as the control group). These pastes were compared regarding their antibacterial effects against Enterococcus faecalis using agar diffusion and microdilution methods. RESULTS: Except for the control group, all prepared pastes showed antibacterial properties. Order of minimum inhibitory concentration for pastes were as followed: CaOH-ZO (1:3)=CaOH-ZO (1:2)>CaOH-ZO (1:1)>CaOH-ZO (3:1)=CaOH-ZO (2:1)>CaOH=ZO-eugenol. Order of minimum bactericidal concentration, which shows a weaker bactericidal effect, according to type of paste, were as followed: CaOH-ZO (1:3)>CaOH-ZO mixture (1:2)>CaOH-ZO mixture (1:1)>CaOH-ZO mixture (3:1)=CaOH-ZO (2:1)>CaOH=ZO-eugenol. Only CaOH-ZO (1:3) and CaOH-ZO (1:2), showed significantly weaker MICs and MBCs (p < 0.001). CONCLUSION: Considering the limitations of an in-vitro study, in terms of anti-bacterial effects against Enterococcus faecalis, CaOH-ZO mixture (2:1) is equivalent to ZO-eugenol as the most commonly used material in polypectomy of primary teeth.

A comparative evaluation of APF gel, CPP/ACP paste alone and in combination with carbon dioxide laser on human enamel resistance to acid solubility using atomic absorption spectrometry: an in-vitro study.

BACKGROUND: The aim of this study was to compare the effects of acidulated phosphate fluoride (APF) gel, calcium phosphopeptide-amorphous calcium phosphate (CPP/ACP) paste alone and in combination with CO2 laser on the resistance of enamel to acid solubility. METHODS: Ninety enamel sections were obtained from 15 extracted teeth and were randomly assigned to six groups: 1) control group; 2) APF group; 3) CPP-ACP group; 4) CO2 laser group; 5) APF + CO2 group; and 6) CPP-ACP + CO2 group. The specimens were individually demineralized in 0.1 M lactic acid solution with adjusted pH of 4.8 for 24h at 37 ºC. The acid solubility was determined using atomic absorption spectrometry. Statistical analysis was done using one-way ANOVA and Tukey-Kramer post hoc test (P<0.05). RESULTS: The average extent of calcium ion released (ppm) was estimated as follow: group 1: 6.974±1.757, group 2: 5.363±1.383, group 3: 6.962±1.489, group 4: 6.890±1.560, group 5: 4.803±1.080 and group 6: 6.789±1.218. Based on the between-group comparison results, group 2 and group 5 showed significant differences with the other groups. CONCLUSIONS: Under the studied conditions, only, the APF group alone and in combination with CO2 laser could decrease enamel acid solubility.

Impact of Nano Hydroxyapatite, Nano Silver Fluoride and Sodium Fluoride Varnish on Primary Teeth Enamel Remineralization: An In Vitro Study.

INTRODUCTION: Dental caries is still prevailing worldwide, although different anti caries products have been introduced. Each remineralizing agent has its own shortcomings. Therefore, looking for new agents to have benefits of previous ones with lesser side effects is worthwhile. AIM: To determine the remineralization ability of NaF varnish, nano-Hydroxyapatite Serum (n-HAP) and Nano Silver Fluoride (NSF) on enamel of primary anterior teeth. MATERIALS AND METHODS: Incipient caries were induced in primary sound anterior teeth by storing each specimen in demineralization solution for 72 hours. Then they were randomly divided into four groups of 15 samples each: (1) NaF varnish; (2) n-HAP repairing serum; (3) NSF and (4) no treatment (control). Surface Microhardness (SMH) was assessed with Vickers micro hardness tester before and after demineralization and after 10 days of pH-cycling. A total of 12 random specimens from groups 1 to 4 (3 random samples of each group) were examined by Atomic Force Microscopy (AFM). The SMH values were analysed with one-way and repeated measures ANOVA. Level of significance was set at p=0.05. RESULTS: Post lesion SMH values significantly decreased in all groups (p<0.001). Post treatment SMH values significantly increased in comparison to post lesion ones (p<0.001) except for control group which was not different statistically (p=0.86). The highest SMH values were observed in NSF group (mean 222.90 ± 28.79). Statistically significant differences were shown between all groups (p<0.05). However, NaF varnish and n-HAP groups were not statistically different (p=0.165). AFM images demonstrated protective layers in all treated groups. CONCLUSION: The results of this in vitro study suggest that NSF could have the greatest remineralization efficacy. NaF varnish and n-HAP serum were similar in remineralizing initial caries. Future clinical studies are recommended for selection of the most appropriate remineralizing agent in primary teeth.

The Comparison of Learning and Memorization Rate of English Among Sari Male Students in Secondary Schools (2010-2011).

BACKGROUND: The aim of present study was to investigate the learning and memorization rate of English based on authentic and traditional assessment approaches in Sari secondary schools. METHODS: It was performed in semi- experimental method. The sample included 60 first year high school male students, selected randomly. Then it has been divided in two groups as experimental and control groups. Assessment devices used in this research included: academic achievement pre-test of English, academic achievement post-test revised questionnaire of attitude toward tests (SAAS-R), and English performance test Before carrying the authentic and traditional assessment approaches into execution, two groups had been taken the scholar academic achievement pre-test in order to assure not to be any significant differences between two groups. After the execution of above mentioned method (about 14 weeks), the academic achievement post-test, and performance test and attitude toward tests (SAAS-R) were performed. Moreover, 2 months after post-test, it was repeated to measure the rate of memorization. In order to analyze data the statistical method, the dependent and independent T- tests were used to determine mean differences of two groups and K2 test was applied to assign the differences of two groups' attitude toward tests. RESULTS: The results implied that: The rate of students' performance learning in authentic assessments is more than the traditional ones. CONCLUSION: There was no significant difference between two group's post-test scores. The rate of memorization in authentic methods is more than the traditional ones. The attitude toward tests in authentic methods is more positive than the traditional ones.

The Effect of Iranian Customary Used Probiotic Yogurt on the Children's Salivary Cariogenic Microflora.

STATEMENT OF THE PROBLEM: Dental caries is the most common disease of childhood. Using probiotics has recently been introduced to reduce the incidence of dental caries.It consists of live microbial food supplements that beneficially affect the host, and hence are considered an alternative way to eradicate the infections. PURPOSE: The aim of this study is to evaluate the effect of consumption of probiotic yogurt on the children's salivary cariogenic microflora. MATERIALS AND METHOD: A double-blind randomized study was performed recruiting 2 parallel groups; 24 healthy children in the case and 25 children in the control group. All healthy children were followed- up over 4 periods. Periods 1 and 3 were wash-out periods with duration of 1 and 2 weeks, respectively. During periods 2 and 4 (2weeks duration each), the case group consumed 200g yogurt containing Bifidobacterium lactis (1×10(6) per gram) once daily and the control group consumed normal yogurt. Salivary Streptococci mutans and Lactobacilli were enumerated before and after the yogurt consumption periods. Pre- and post-treatment values within and between regimens were compared using the t-test and paired samples. RESULTS: There was a reduction in Streptococcus mutans and Lactobacillus counts in the control group, but for Streptococcus mutans, the count reduction between phases 1 and 4 was statistically significant (p= 0.009). In the case group, neither the Streptococcus mutans count nor the Lactobacilli count was significantly reduced. CONCLUSION: Based on the findings of this study, short-term daily consumption of probiotic yogurt containing Bifidobacterium lactis could not reduce the levels of salivary Streptococcus mutans and Lactobacilli in 6 to 12 year-old children, while normal yogurt could reduce the Streptococcus mutans counts significantly.

The effect of applying podcast multimedia teaching system on motivational achievement and learning among the boy students.

BACKGROUND: Traditional education classes are no more effective because they are tied to a particular place and time. Podcast complete the defection of other educational resources. In this study we aimed to address whether utilizing podcast multimedia training system has an effect on the motivational achievement and students learning of the Arabic course in high school. METHODS: In this practical-purposed, descriptive and quasi-experimental study, pre- and post-test method in control and experiment groups was used. Researchers used simple random sampling method to form the groups. RESULTS: The results showed the normal distribution of data according to the value of z (0.09) in the pre- and post-tests in both control and experiment groups. Therefore, the data distribution was normal (P>0.925). Significant differences between experimental and control groups in terms of academic level were not observed in the pre-test. There was no significant difference between the motivational achievement of education in post-test of control and experiment group (p>0.89). CONCLUSION: The results showed that teaching with podcast multimedia systems significantly increased learning of Arabic in the high school level. But of motivation reinforcement between traditional method and system for multimedia podcasts, showed no significant differences. Each variety of multimedia techniques can be beneficial for a specific course. Therefore, more studies on the effectiveness of podcast method in different courses to determine its effects are necessary.

The Relationship between Field Dependent-Independent Cognitive Style and Understanding of English Text Reading and Academic Success.

BACKGROUND: The learning styles are the distinctive learners' strategies for information processing and discovering new concepts. One of the most important kinds of learning styles is the Witkin's theory of field dependence-independence cognitive style. OBJECTIVE: This study seeks to find the relationship between field dependence -independence cognitive style and English text reading comprehension, learning English as a foreign language, academic achievement and the choice of academic courses. METHODS: In this study, 305 students (both girls and boys) studying at the junior level at high school in Sari were randomly selected through multistage selection who responded to Group Embedded Figures Test (GEFT). RESULTS: The data analysis was conducted by using regression analysis which showed that FDI cognitive styles determined the changes in dependant variables of reading comprehension score, learning English and the total average with the respective values of %8.8, %9.2 and %11.6 (p <0.05). CONCLUSION: Regarding the findings, it can be concluded that the more field independent, the higher the reading comprehension skills and learning English and the more academic achievement will result. The results of this study can help in selecting students' courses and also better directing the learners to improve their learning.

The Effects of Problem-Solving Teaching on Creative Thinking among District 2 High School Students in Sari City.

INTRODUCTION: Nowadays, regarding the learners' needs and social conditions, it is obviously needed to revise and reconsider the traditional methods and approaches in teaching. The problem solving approach is one of the new ways in Teaching and learning process. This study aimed at studying and examining the effect of "problem-solving" approach on creative thinking of high school female students. METHODS: An experimental method is used for this research. In this research, 342 out of 3047 female-students from Sari high schools were randomly selected. These 342 students were divided into two groups (experimental and control) in which there were seven classrooms. The total number of students in every group was about 171. After testing them with Jamal Abedi creativity test, it was revealed that two groups were equal in creativity score. The tests were done through Requirements. The experimental group was taught by problem solving method for three months while the control group was taught by traditional method. RESULTS: The research results showed that using descriptive indices and t-test for the two independent sample groups in which problem solving teaching method was used in teaching processes had an effect on creativity level in comparison with traditional method used in the control group. CONCLUSION: Considering the results of this study, the application of problem-solving teaching methods increased the creativity and its components (fluidity, expansion, originality and flexibility) in learners, therefore, it is recommended that students be encouraged to take classes on frequent responses on various topics (variability) and draw attention on different issues, and expand their analysis on elements in particular courses like art (expansion). To enhance the learner's mental flexibility and attention to various aspects, they are encouraged to provide a variety of responses.