Statement of Problem: The use of dentine bondings on enamel and dentin in total etch protocols has recently become popular. Unfilled resin is hydrophobic and dentin bonding is hydrophilic in nature. This chemical difference could be effective in enamel bonding process.Purpose: The aim of this study was to compare the shear bond strength of unfilled resin to dry enamel and dentin bonding to dry and moist enamel.Materials and Methods: In this experimental study, a total of 30 incisor teeth were used. The specimens were randomly assigned to three groups of 10. 37% phosphoric acid etchant was applied to the enamel surfaces in each group for 15 seconds, rinsed with water for 20 seconds and dried for 20 seconds with compressed air in groups one and two. After conditioning, group 1 received unfilled resin (Margin Bond, Colten) and group 2 received dentin bonding (Single Bond, 3M) and in group 3 after conditioning and rinsing with water, a layer of dentin bonding (Single Bond) was applied on wet enamel. The enamel and dentin bonding were light cured for 20 seconds. A ring mold 3.5 mm in diameter and 2 mm height was placed over the specimens to receive the composite filling material (Z100, 3M). The composite was cured for 40 seconds. The specimens were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. The findings were analyzed by ANOVA One-Way and Tukey HSD tests.Results: Shear bond strength of dentin bonding to dry enamel was significantly less than unfilled resin to dry enamel (P<0.05). There was no significant difference between the bond strength of dentin bonding to moist and dry enamel. In addition bond strength of dentin bonding to wet enamel was not significantly different from unfilled resin to dry enamel.Conclusion: Based on the findings of this study, it is suggested that enamel surface should remain slightly moist after etching before bonding with single bond but when using unfilled resin, the enamel surface should be kept dry.

Objectives: Incorporation of fillers might improve the physical properties of sealants. This systematic review and meta-analysis evaluated the retention and caries development rate of filled and unfilled fissure sealants. Materials and Methods: This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. The PubMed, Scopus, Embase, Cochrane Database of Systematic Reviews, and ISI Web of Knowledge were searched until October 24, 2019. The risk of bias (ROB) was assessed for the included studies based on the Cochrane collaboration common scheme for bias, and the meta-analysis was performed through a random effects model. Results: The search resulted in 6, 336 unrepeated relevant studies. After the title, abstract and full-text screening, 19 studies with 26 comparing groups were finally included in this systematic review and meta-analysis. According to the included studies, both retention rate and caries development in filled and unfilled resin-based sealants did not significantly differ within 2 years of follow-up. Conclusion: Since there was no significant difference in the retention rate and caries development between filled and unfilled sealants, it seems that the final decision should be made uniquely for each patient according to the type of fissure, patient’, s age, habits, etc.

Statement of Problem: Porcelain restorations are susceptible to fracture and a common method for repairing is the use of silane and composite on etched porcelain. Although HF is very effective in porcelain etching but has detrimental effects on tissues. Purpose: In this study, the effect of APF and PHA was compared with HF in porcelain etching. Also the role of silane, unfilled resin and dentin bonding in bond strength of composite- porcelain was evaluated.Methods and Materials: In this experimental in-vitro study, one-hundred twenty porcelain square blocks (5´5´2 mm) were prepared and bonding surfaces of each sandblasted. Samples were divided into three groups. The first group (n=40) were etched with buffered HF 9.5% (Ultradent) for 1 min., the second group (n=40) were etched with Iranian APF 1.23% (Kimia) for 10 minutes and the third group (n=40) were etched with Iranian PHA 37% (Kimia) for 1 min. Ultradent silane was applied on the surfaces of half of cases in each group. On the surfaces of half of silane-treated samples unfilled resin was applied and dentin bonding was used on the surfaces of the remaining. Samples without silane were treated in a similar manner. Composite cylinder with 4mm diameter and 2 mm height was bonded to porcelain. Specimens were stored in 37°C distilled water for 24 hours and subjected to 500 cycles. Shear bond strength was measured with an Instron machine and type of fracture was evaluated using a stereomicroscope. Results were analyzed using 3 way ANOVA, Kaplan- Maier and Tukey HSD tests.Results: Findings showed that PHA and APF roughened the porcelain surface without creating retentive micro undercuts but HF etches porcelain and creates retentive microundercuts. Ultradent silane had no significant effect on bond strength of porcelain- composite. Unfilled resin with Ultradent silane compared with dentin bonding with the same silane is more effective in bond strength of composite- porcelain.Conclusion: Based on present study, application of Ultradent silane on sandblasted and etched porcelain with PHA or APF cannot be used as an alternative to this silane on sandblasted and etched porcelain with HF.

Background and Objective: T3 resin uptake test indicates the availability of thyroxin binding globulin (TBG), which is the carrier of a large amount of T3 and T4 in blood. We aimed to study the relationship between serum T3 Resin Uptake and serum lipids profile.Material and Methods: The participants aged 14.80±38.29 were both males (59; 29.5%) and females (141; 70.5 %). T3 Resin Uptake was measured by Immunoassay method and serum lipid profile components (cholesterol, triglycerides, HDL-C, LDL-C, and VLDL) were measured by the kit. Results: Significant negative correlation was observed between serum T3 Resin Uptake and cholesterol, triglycerides and LDL-C (P£0.05), but that was not the case for HDL-C and VLDL.Conclusion: Serum T3 Resin Uptake can be evaluated to assess the risk factors related to cardiovascular disorders.

Objectives: Pit and fissure sealants are recognized as an effective preventive approach in pediatric dentistry. Composite resin is the most commonly used sealant material. Adding nanoparticles to composite resin could result in production of flowable composite with higher mechanical properties and better flowability than previous sealants. This study aimed to compare the microleakage of a flowable nanocomposite and materials conventionally used as pit and fissure sealants. Materials and Methods: A total of 185 extracted mandibular third molar teeth were selected and randomly divided into 5 groups (n=36): flowable nanocomposite, flowable composite, filled sealants, nano-filled sealants, and unfilled sealants. Five teeth were reserved for examination under a scanning electron microscope (SEM). The samples were thermocycled (5-55° C, 1-minute dwell time) for 1000 cycles and immersed in 0. 2% fuchsine solution for 24 hours. Teeth were sectioned buccolingually. Microleakage was assessed qualitatively and quantitatively by means of dye penetration and SEM. Data were analyzed using chi-square, Kruskal-Wallis, and Bonferroni-corrected Mann-Whitney U tests. Results: Qualitative microleakage assessment showed that flowable composite and nanofilled flowable composite had almost no microleakage (P<0. 001). Regarding quantitative scores, the nanofilled flowable composite and unfilled fissure sealant showed the lowest and the highest rate of microleakage, respectively. No statistically significant difference was found between the two flowable composites (P=0. 317). Filled resin-based sealant had significantly lower microleakage than unfilled resin-based sealant (P<0. 001). Conclusion: Use of flowable and nanofilled flowable composites (but not unfilled resin-based fissure sealant) is recommended for sealing of pits and fissures of molars.

The strength of rock mass is significantly controlled by the presence of discontinuities and instabilities at shallow depth may occur by sliding along rock joints. This phenomenon is more important at shallow depths. The aim of this study is to investigate the shear behavior of natural, unfilled rock joints that were obtained from core drilling. For this purpose, direct shear tests were conducted on 37 natural rock joints in constant normal loading condition. All the specimens were obtained from core drilling of a geotechnical project. The morphological characteristics of joints were captured by photogrammetry before the test. Based on Barton and other classical theories, laboratory test data, and using the quantitative three-dimensional morphological parameters, a new peak shear strength criterion has been proposed for natural, unfilled rock joints. The predicted peak strengths using the new model match well with the observed values. In addition, a comparison of the new criterion with previous 3D models shows that compared to other criteria, the predicted value based on the new criterion is more consistent with the test data. It was observed that the estimation accuracy of the new criterion is appropriate for natural, unfilled joints.

Statement of Problem: One of the factors leading to failure of sealant therapy is microleakage. Various materials and methods have been recommended in order to reduce this phenomenon. They include the use of sealants with high and low filler content and the use of adhesives and other conditioning systems for preparation of etched enamel surface.Purpose: The aim of this experimental study was to assess the effect of one-bottle adhesive system on the marginal microleakage of the filled and unfilled fissure sealant.Materials and Method: Forty extracted human caries-free premolars were randomly assigned into 4 groups of 10. The teeth in each group were sealed according to the following protocols: 1) etching+unfilled sealant (clinpro) 2) etching+filled sealant (Delton Fs Å) 3) etching+single Bond+unfilled sealant 4) etching +single Bond+filled sealant. The teeth were then thermocycled (500 cycles between 5oC and 55oC) and immersed in 1% buffered methylene blue dye for 24h. Each tooth was divided into three sections, and each section was analyzed for microleakage, using a stereomicroscope. Kruskall-Wallis test was used for comparison of microleakage among the four groups.Results: The results showed that all the groups had some degree of microleakage and there was not any significant difference among them (p>0.05).Conclusion: The addition of filler particles to sealants and using a bonding agent system (Single Bond) had no effect on reduction of the microleakage.