Backgroud and Aim: microleakge is one of the most common cause of failure in restorative dentistry in this study the microleakge of Filtek p90, Filtek p60 was evaluated and compared. Materials and Methods: In this experimental study, on 48 premolar teeth standardized class II MOD preparations were made cervical margin of mesial preparation were 1mm above the CEJ and 1 mm and the distal preparation were 1 mm below the CEJ Samples divided in to 3 groups of sixteen teeth. A group: teeth were filled with Filtek silorane (3M ESPE, USA) and silorane system adhesive self-etch primer and bond. B: teeth were filled with Filtek silorane and Adper single bond plus. C: sixteen teeth were filled with Filtek p60 and Adper single bond plus. After AgNO3 dye opplicaiton microleakage were evaluated by stereomicroscope. data were statistically analyzed by kurskal-wallis and Wilcoxon. the level of 0. 05 considered significant. Results: The most enamel microleakage was related to C and lowest enamel microleakge was shown in A group. The most dentin microleakage was related to B and the lowest dentin microleakge was shown in A group. Microleakage was significantly different between A, with B and C (P‹ 0. 05) dentin microleakage was not significant difference between B and C. Conclusion: Type of Composite and bonding effect to microleakage, the lowest microleakage was gingival margine irrespective of the location of the margine related to group A.

Abstract Introduction: The incremental filling technique in traditional Resin Composites results in reduced polymerization shrinkage. However, many products have recently been introduced as low-shrinkage Resin Composites that make the bulk-filling of cavities possible. Materials and Methods: Three identical dental models from a premolar tooth were made using a CADCAM digital scanner in the solid work software environment. MOD cavities were designed and filled by Tetric EvoCeram® Bulk Fill, GC KALORE™, and 3M ESPE Filtek p60 (control group) Resin Composites. Incremental and bulk-fill techniques were used for Tetric EvoCeram® Bulk Fill while GC KALORE™, and 3M ESPE Filtek p60 Resin Composites were used with incremental technique in Ansys 16 simulation software environment. Stress distribution and cuspal deflection rate were analyzed in Ansys 16 software by Kruskal–Wallis and Mann-Whitney U tests. Results: The mean stress intensity for Tetric EvoCeram® Bulk Fill in the bulk-fill technique was more than the incremental technique. Cuspal deflection rate and stress distribution among the Resin Composites, GC KALORE™, Tetric EvoCeram® Bulk Fill, and 3M ESPE Filtek p60 were in ascending order, respectively. Stress distribution was more uniform in the incremental technique. Conclusion: The GC KALORE™ Resin Composite had the least stress distribution and cuspal deflection rate.

Composite Resin is a kind of polymer that has been recently substituted for Amalgam; therefore biocompatibility of Composite with periodontal tissue should be acceptable and also should not clinically induce inflammation and irritation symptoms in gingival tissue over a long time.The objective of this research is to investigate biocompatibility of posterior Composite with periodontal tissue by means of PPD and Bap indices in teeth which have been filled with Composite and intact ones.This is a clinical trial research and a kind of case control in which 40 teeth of 20 patients-15 men and 5 women- were selected from students of Dentistry Faculty of Tehran Medical Science University as the case group with cl II caries in posterior teeth (4, 5, 6, 7) and the outline of preparation was near or 0.5 coronal to gingival which were filled with posterior Composite Resin (p60).PPD indices - based on ranking of 1 to 4 - and Bap - based on Muhlemann category were measured and recorded exactly before operation and 3 and 6 months after in 40 restored case groups and 40 control group (intact teeth in opposite quadrant). Then the results were analyzed by means of SPSS software and tested by Friedman and Wilcoxon Tests.There was no significant difference between Bap Indices in T0-T1 and T2 in case group and also in control group. Further more there was no significant difference in PPD Indices in T0-T1and T2in case and control groups.There was no significant difference between Bap indices in case and control teeth groups in T0 (exactly before operation). Also there was no significant difference between mentioned teeth groups in T1 (3 months after operation). But a significant difference was found between them in T2 (6months after operation) (P=0.035) Furthermore there was no difference between PPD indices in case and control teeth groups in proximal side of buccal surface in T0,T1 and T2 and also no significant difference on the proximal side of lingual surface in T0,T1 and T2. Regarding biocompatibility of new generation posterior Composite Resin (like p60) with periodontal tissue, they have not been able to compete with the intact surface of tooth.  

Introduction: The purpose of this study was to evaluate the fracture resistance of premolars with mesio-occluso-distal (MOD) preparations restored with two different Resin Composites along with three placement methods.Materials and Methods: In this in vitro study, sixty human sound maxillary premolars mounted in acrylic Resin were randomly divided into two groups according to the type of Composite restoration (Filtek p60, Nulite F). Each group was further subdivided into three subgroups according to the type of placement methods namely Bulk, Centripetal and Fibre Insert (n=10). The same adhesive system, Single Bond, was used for Composite bonding following manufacturer's instructions for all teeth. Specimens in groups 1, 2 and 3 were restored with Filtek p60 Resin Composite while in groups 4, 5 and 6 Nulite F was applied. After 24 hours storage in 37oC, a 4 mm diameter steel sphere in Universal Testing Machine was contacted the buccal and lingual cusps of the tested teeth at a crosshead speed of 5 mm/min until fracture occurred. Data were subjected to analysis of variance and Duncan tests (p value<0.05).Results: Groups 3 and 6 showed a higher fracture resistance than other groups (P=0.001).Among the placement methods, Fibre insert showed a significant result (P=0.0001) but the type of Composite was insignificant (P=0.791).Conclusion: It seems that on MOD cavities, contrary to the type of materials used, the insertion method, largely influences fracture resistance of premolar teeth restored with Resin Composite.

Objectives: Dental Composite wear in posterior restorations is a concern and is affected by different factors. This study was conducted to evaluate the effect of polishing and mechanical loads on wear of silorane-based and methyl methacrylate-based Composites Resins.Materials and Methods: Of each dental Composite (Filtek P90 and Filtek p60), 40 samples were fabricated in a polyethylene mold (4mm diameter, 10mm height). According to the finishing and/or polishing protocols (180-grit or 2500-grit silicon carbide papers), the samples of each Composite were divided into two groups. Surface roughness (Rǝ) was measured and recorded using a contact profilometer. The weight of each sample was also measured in grams. The wear test was performed in a pin-on-disc device under two different loads (70N, 150N). Afterwards, samples were subjected to profilometry and their weight was measured again. Data were analyzed using t-test and univariate ANOVA. P<0.05 was considered statistically significant.Results: Higher mechanical load resulted in greater weight loss (P<0.001). Samples polished with 2500-grit papers showed significantly lower Ra changes compared to those polished with 180-grit papers (P<0.001). Filtek P90 had greater weight loss than Filtek p60 except in one condition (180-grit, 70N).Conclusions: Results showed that wear of posterior Composite restorations depends on mechanical load, type of Composite Resin and surface properties.

Objectives: The aim of this study was to evaluate enamel and dentinal microleakage in Class II cavities restored with silorane-and methacrylate-based Resin Composites using specific and nonspecific adhesives. Materials and Methods: Thirty-six caries-free human premolars were used. Two Class II cavities were prepared on each tooth. The gingival floor was set at 1 mm above (on the mesial surface) and at 1 mm below (on the distal surface) the cementoenamel junction (CEJ). The samples were randomly divided into four groups, and the cavities were restored with a methacrylate-based Composite (Filtek™ p60) and a silorane-based Composite (Filtek™ P90) with specific and nonspecific adhesives. Microleakage was tested using a standardized dye penetration method. All samples were examined under a stereomicroscope, and microleakage scores were statistically analyzed using Kruskal-Wallis and Mann-Whitney-U tests. One sample from each group was examined under a scanning electron microscope (SEM) to determine the bonding area. Results: No significant difference was found between the groups in terms of the enamel microleakage (P=0. 086). There was a significant difference between the groups with regard to dentinal microleakage (P=0. 003). No significant reduction in microleakage was observed in groups restored with Filtek™ P90 Composite using its specific adhesive compared to those restored with Filtek™ p60 Composite using its specific adhesive (P=0. 626). Conclusions: The results indicated that the application of methacrylate-and silorane-based Composites with specific or nonspecific adhesives had no impact on enamel microleakage, but it affected dentinal microleakage, and specific adhesives showed less microleakage. It seems that a phosphate-methacrylate-based intermediate Resin is required to bond dimethacrylate adhesive to silorane-based Composites.

Statement of Problem: Patients’ demand for tooth-colored restoratives in the posterior region is increasing. Clinicians use universal nanohybrid Resin Composites for both anterior and posterior regions. There are few published reports comparing fracture toughness of nonohybrids and that of hybrid Composite stored wet and dry.Objectives: To investigate the fracture toughness of three nanohybrids compared to that of a hybrid Resin Composite stored dry or wet up to 60 days, using four-point bending test.Materials and Methods: Four Resin Composites were used: three nanohybrids; Filtek Supreme (3M), Ice (SDI), TPH3 (Dentsply) and one hybrid Filtek p60 (3M). For each material, 40 rectangular notched beam specimens were prepared with dimensions of 30 mm ´ 5mm ´ 2mm. The specimens were randomly divided into 4 groups (n=10) and stored at 37oC either in distilled water or dry for 1 and 60 days. The specimens were placed on the four-point test jig and subjected to force (N) using universal testing machine loaded at a crosshead speed of 0.5mm/min and maximum load at specimen failure was recorded and KIc was calculated.Results: Three-way ANOVA showed a significant interaction between all the factors (all p<.0001). Except for TPH3, all tested materials showed significantly higher KIc when stored dry than stored wet (p<0.05). After 1 day of dry storage, Ice showed the highest KIc (2.04 ± 0.32) followed by Filtek p60 and the lowest was for Filtek Supreme (1.39 ± 0.13). The effect of time on fracture toughness was material dependent.Conclusions: Wet storage adversely affected the fracture toughness of almost all materials. Keeping the restoration dry in the mouth may increase their fracture toughness. Therefore, using a coating agent on the surface of restoration may protect them from early water uptake and increase their strength during a time period.

Background and Aims: Packable Composites with high viscosity might not adapt properly to internal surfaces and cervical areas. The aim of this study was to assess the microleakage of class II posterior Composite restorations performed using different methods.Materials and Methods: Ninety proximal cavities were prepared in extracted sound premolar teeth, divided into three groups and filled as follows: 1- packable Composite (3M Filtek p60), 2-Hybrid Composite (Z250) +p60 Composite and 3- Resin-modified glass ionomer liner+p60 Composite. Afterwards, the samples were immersed in 0.5% Foushin solution and sectioned. Gingival microleakage was then graded. Obtained data were analyzed using paired t-test and analysis of variance.Results: In regard to distal cavities, significant difference was seen between the groups 1 and 3 (P=0.01) as well as groups 2 and 3 (P=0.03). Comparing microleakage of mesial and distal cavities, there was a significant difference in groups 1 (P=0.003) and 2 (P=0.005).Conclusion: Based on the findings of this study, application of Z250 Composite had no effect on reduction of microleakage of class II posterior Composite restorations. Vitremer liner decreased microleakage in dento-gingival margins.

Background and Aim: Discoloration of dental Composite Resins is one of the most common reasons for replacement of Composite restorations which may cause patient dissatisfaction and additional time and expenses for replacement. Tea is the most common drink among Iranians which is largely responsible for discoloration of Composite restorations. The purpose of this study was to evaluate the effect of two types of tea (Iranian and imported) on discoloration of two commonly used microhybrid Composite Resins (FiltekZ250 and Point4).Materials and Methods: This experimental and invitro study was done on 30 specimens made from two Composites FiltekZ250 and Point 4. The primary color measurement was done with spectrophotometer before immersing the samples in separate mediums. The specimens from each type of Composites were randomly divided into three groups, each of which was then immersed in a different medium (Iranian tea, imported tea and distilled water). While immersed in the prepared mediums, the samples were stored in a 37oc incubator for one week, after which time, the final color measurements were taken. Results were statistically analyzed with one way ANOVA test.Results: When exposed to the medium containing imported tea, the reported color changes in FiltekZ250 and Point 4 Composites were measured to be: 11.84±1.71, 12.29±4.10 and when exposed to the Iranian tea it was reported:7.87±0.85,5.98±2.12. Both Composite Resins showed a significant color changes (P<0.001) which was not clinically acceptable (DE>3.3). The two Composites did not show any significant difference in discoloration rate. (P>0.05).Conclusion: Both micro-hybrid Composites (Filtek Z250,Point4) demonstrated color changes which were clinically unacceptable. The imported tea caused more discoloration compared to the Iranian one.

Introduction: The characteristics of a suitable restoration material is having acceptable mechanical properties، protecting teeth against decay and ease of use in clinics. Diet can affect properties of restorative materials in the mouth. Since amongst important properties of Composite restorations are mechanical properties such as hardness، the aim of this study was evaluation of the effect of Coca- Cola Beverages on surface hardness of a silorane based (p90) and methyl methacrylate (p60) Composites.Methods: In this experimental study ,thirty disc- shaped specimens (5×2 mm) of each of methyl methacrylate based (Filtek p60، 3M Dental Products, USA) and a silorane based (Filtek p90، 3M Dental Products ,USA) Composite Resins were prepared ,according to manufacturers' instructions. Specimens were randomly divided to four groups as follows (N=15): G1: Filtek p90 without exposure to Coca-Cola ,G2: Filtek p90 with exposure to Coca- Cola ,G3: Filtek p60 without expure to Coca-Cola ,G4: Filtek p60 with expure to Coca- Cola. The specimens were exposed to regular soft drinks Coca- Cola ,(Khoshgovar,  Tehran ,Iran) at room temperature for seven days with a frequency of three times daily for 20 minutes at a time. In the remaining times of the day ,they were kept in distilled water. Then ,micro hardness measurements were made for each specimen with a Vickers hardness testing machine (Buehler ,Lake Bluff ,IL ,USA) under 500 g of force for 15 seconds. Data were analyzed using SPSS 18 and independent t- test at a significance level of 0.05Results: Micro hardness values of four groups were G1: 68.28±2.65; G2:59.56±6.61; G3:93.5±2.38; and G4:86.76±5.47 ,respectively. The results of this study showed that Coca-Cola reduces the surface hardness of the two Composite materials (P<0.05).Conclusions: The results showed the hardness of both Filtek p90 and Filtek p60 Composite significantly decreases with Coca- Cola yet the reduction was equal.