Journal of Dental Medicine

Background and Aim: Sodium hypochlorite can remove the organic phase of the demineralized dentin and it produces direct resin bonding with hydroxyapatite crystals. Therefore, the hydrolytic degradation of collagen fibrils which might affect the bonding durability is removed. The aim of this study was to evaluate the effect of collagen fibrils removal by 10% NaOCl on dentin shear bond strength of two total etch and self etch adhesive systems.
Materials and Methods: Sixty extracted human premolar teeth were used in this study. Buccal surface of teeth were grounded until dentin was exposed. Then teeth were divided into four groups. According to dentin surface treatment, experimental groups were as follows: Group I: Single Bond (3M) according to manufacture instruction, Group II: 10% NaOCl+Single bond (3M), Group III: Clearfil SE Bond (Kuraray) according to manufacture instruction, and Group IV: Clearfil SE Bond primer. After that, the specimens were immersed in 50% acetone solution for removing extra monomer. Then the specimens were rinsed and dried. 10% NaOCl was applied and finally adhesive was used. Then composite was bonded to the treated surfaces using a 4 2 mm cylindrical plastic mold. Specimens were thermocycled for 500 cycles (5-55ºC). A shear load was employed by a universal testing machine with a cross head speed of 1mm/min. The data were analyzed for statistical significance with One-way ANOVA, Two-way ANOVA and Tukey HSD post-hoc tests.
Results: The mean shear bond strengths of groups were as follows: Single Bond=16.8±4.2, Clearfil SE Bond=23.7±4.07, Single Bond+NaOCl=10.5±4.34, Clearfil SE Bond+NaOCl=23.3±3.65 MPa. Statistical analysis revealed that using 10% NaOCl significantly decreased the shear bond strength in Single Bond group (P=0.00), but caused no significant difference in the shear bond strength in Clearfil SE Bond group (P=0.99).
Conclusion: Based on the results of this study, NaOCl treatment did not improve the bond strength in self etch adhesive and caused a significant decrease in the bond strength of total etch adhesive system.

Background and Aim: Evaluation of shear bond strength and microleakage of bonding agents is important as these properties play main roles in adhesion of composite to dental tissues. Microleakage results in bacterial penetration into dentin tubules and enamel surfaces and causes sensitivity and recurrent caries followed by destruction of composite filling. Insufficient shear bond strength results in early failure of filling in low masticatory forces. The main goal of this study was to compare the microleakage and shear bond strength of an experimental adhesive and Scotchbond multi-purpose (MP) adhesive system.
Materials and Methods: In this experimental study, sixty extracted caries free human molar teeth were randomly assigned into 4 groups of 15 each for shear bond strength. Variables were bonding agents, enamel and dentin. Twenty teeth assigned into 2 groups of 10 each were used for valuation of the microleakage. Microleakage and shear bond strength were performed according to ISO TR 11405. All data were analyzed with parametric and non-parametric tests according to their normality distribution. Also, Weibull distribution performed on data.
Results: Data obtained from both microleakage and shear bond strength tests showed no significant difference between the experimental bonding and Scotchbond MP bonding (P>0.05). Furthermore, there was no significant difference between the microleakage of occlusal and gingival parts of both bondings (P>0.05).
Conclusion: Experimental adhesive bonding showed acceptable results regarding microleakage and shear bond strength. It may be concluded that the experimental dentin bonding had a comparable performance quality with that of commercial system.

Background and Aims: Soft tissue management with providing the esthetic for restoration of a single implant in the anterior maxilla is of great importance. Tissue training helps to develop a proper emergence profile and natural tooth appearance. The aim of this article was to report a nonsurgical management of undesirable contours of soft tissue around maxillary anterior implants to achieve an optimum appearance.

Materials and Methods: A 23-year-old female with congenital missing of maxillary lateral incisors, after completion of a fixed orthodontic treatment and gain enough space, received 2 dental implants. After second phase surgery and healing period, construction of the restorations was not possible through conventional method because of severe soft tissue collapse. In this case, soft tissue contours were corrected using a provisional restoration and then final restoration was made and delivered.

Conclusion: Tissue training with a provisional restoration helps to re-establish normal gingival tissue contours and interdental papillae around the restoration of maxillary anterior implants.

Background and Aims: In this in-vitro study, the effect of multiple adhesive coating on the microshear bond strength of composite to dentin and surface microhardness of dentin after treatment with four adhesives (One Step Plus, One Step, Single Bond, Single Bond 2) were evaluated.

Materials and Methods: One hundred intact human molars were cut to obtain disks of dentin having 2 mm thickness. For the microshear bond test, sixty disks were randomly divided into four groups. In each group one type of adhesive was used. In one half of a disk two layers and in another half six layers of adhesive were applied. Cylinders with 1mm height was filled with a composite and light cured. The cross-head speed was 0.5 mm/min. Vickers microhardness was tested on forty dentin disks which divided into four groups and prepared in the same manner used for microshear bond test. Data were analyzed by Two-way ANOVA and Tukey tests.

Results: The highest and lowest bond strength were recorded as 29.49 ± 5.74 MPa (One Step Plus 6 layers), and 21.23 ± 4.83 MPa (One Step Plus 2 layers), respectively. The results indicated that One Step Plus bond strength in 6 Layers was significantly higher than 2 layers. The highest and lowest dentin hardness values were
39.08 ± 8.34VHN (Single Bond 2 layers) and 28.53 ± 5.98 VHN (One Step Plus 6 layers). None of the adhesives exhibited significant difference in hardness with regards to the layers applied (P>0.05). Presence of filler in adhesives had no significant effect on bond strength (P=0.05) whereas caused significant decrease in the dentin microhardness (P<0.05). In addition, type of solvent had significant effect on the bond strength and bond strength was significantly higher in acetone-base adhesives (P<0.05). However, dentin microhardness was significantly higher in the ethanol-base adhesives (P<0.05).

Conclusion: Multiple adhesive coating had no influence on the microshear bond strength of composite to dentin and dentin surface microhardness. It was dependent on the type of adhesive used.

Background and Aims: Root canal obturation is of great importance in root canal treatment. Its purpose is to eliminate microleakage, re-entry and growth of micro-organisms in the root canal system. The aim of this study was to compare coronal salivary microleakage in obturated root canals using lateral compaction, single cone gutta-percha and System B vertical compaction methods.

Materials and Methods: In this in-vitro study, 80 single rooted, human extracted teeth were randomly divided into 3 experimental groups (n=20) and 2 positive and negative control groups (n=10). The specimens in each experimental group were obturated by using cold lateral compaction, single cone obturation, or continuous wave of condensation (system B). After that, coronal saliva leakage was evaluated. Data were analyzed using Survival analysis and Log-rank test.

Results: The results showed that all the specimens in the positive control group showed evidences of leakage during the first 7 days of study. None of the specimens in negative control group showed leakage during the 30-days period of the experiment. Survival test and log-rank test showed that at the end of the 30 days, there was significantly less resistance to coronal salivary leakage in single cone method compared with lateral compaction (P=0.039) and continuous wave of condensation (P=0.019) groups. No significant difference was observed between lateral compaction and System B vertical continuous method (P=0.564).

Conclusion: Based on the results of this study, lateral compaction and system B groups showed higher resistance against the coronal leakage compared with single cone group.

Background and Aims: Considering advantages and disadvantages of mineral trioxide aggregate (MTA), Calcium Enriched Mixture (CEM) cement has been developed recently. The purpose of this study was to compare the apical microleakage of the root-end cavities prepared by ultrasonic or Er,Cr:YSGG laser and filled with MTA or CEM cement.

Materials and Methods: Eighty single-rooted, extracted human teeth were instrumented and obturated. Root-end resection was made by removing 3 mm of the apex. The teeth were randomly divided into two experimental (n=30) and two positive and negative control (n=10) groups. After that, the retrograde cavities were prepared using ultrasonic or Er,Cr: YSGG Laser. According to the root-end filling materials (MTA or CEM cement), each group was then divided into two subgroups. Finally, specimens were cleared for assessing the amount of apical dye (Indian ink) penetration. The data were analyzed using Kruskall-Wallis and Dunn tests.

Results: Laser/CEM cement group showed significantly the lowest mean apical dye penetration. There were no statistically significant differences between Laser/MTA, ultrasonic/MTA and ultrasonic/CEM cement groups.

Conclusion: Based on the findings of this study, CEM cement demonstrated lower rate of apical leakage compared with MTA, when the root-end cavities prepared with Er,Cr:YSGG Laser. The sealing ability of MTA was not different following root-end preparation by ultrasonic or Er,Cr:YSGG Laser.

Background and Aims: This ex vivo study was done to evaluate the effect of different adhesive systems on microleakage of class V composite restorations.
Materials and Methods: Thirty extracted human third molar teeth were selected and class V cavities were prepared (3×3×1.5 mm) on buccal and lingual surfaces. Then, teeth were divided into 3 groups. Adhesives used in this study were Excite (Ivoclar/Vivadent), AdheSE(Ivoclar/Vivadent) and AdheSE-one Ivoclar (Vivadent/Vivadent). After application of adhesives, cavities were restored with a resine composite (InTen-S A1/ Ivoclar), in 3 increments and cured with QTH light curing unit (700 mW/cm). After 24 hours storage of teeth in 370C water, teeth were thermocycled (500 cycles in 5-550C) and stored in 1% basic fushin for 24 hours. After that, the specimens were rinsed with running water and mounted in a self-cured acryl. Finally, the specimens were sectioned and maximum depth of dye penetration for each restoration was measured using stereomicroscopy. The results were statistically analyzed with Mann-Whitney U test.
Results: In comparison between enamel and dentin margins in each group, microleakage in enamel margins were less than that of dentin margins. This difference was statistically significant in Excite and AdheSE-one groups (P=0.001, P=0.043). AdheSE showed the least microleakage in dentin margins however, there was no significant difference between 3 bonding agents (P=0.14). In enamel margins, there were significant differences between 3 bonding agents (P=0.001). Excite showed the lowest microleakage and AdheSE-one had the highest microleakage.
Conclusion: The least enamel microleakage was associated with the total-etch and least dentin microleakage was observed in the two-step self-etch adhesive system.

Background and Aims: Nowadays, calcium hydroxide is used as a dressing for canal sterilization and repair progression of apical lesions. The aim of this study was to investigate the effect of calcium hydroxide as an intracanal medicament on the apical microleakage of root filling.
Materials and Methods: In this experimental study, 46 extracted single-rooted human teeth were instrumented with step-back technique to master apical file (MAF) size 35. Specimens were randomly divided into 2 groups (n = 20). In group 1, the specimens were treated with calcium hydroxide intracanal medication and in group 2, the samples did not receive any medication. The teeth were incubated in 100% humidity at 37°C for one week. After that, calcium hydroxide was removed using irrigation with normal saline and reaming with MAF. The root canals were obturated with gutta- percha and AH26 sealer using lateral compaction technique. Specimens were incubated in 100% humility at 37°C for 72 hours and then immersed in India ink for 1 week. Finally, the teeth were cleared and the maximum linear dye penetration was measured under a stereomicroscope at 4X magnification. The data were analyzed by T-test and Chi-square.
Results: There was no significant difference between the two experimental groups (P=0.068).
Conclusion: The findings of this study indicated that using calcium hydroxide as an intracanal medicament did not influence the apical microleakage after final obturation of the root canal system.

Background and Aims: Marginal seal in class V cavities and determining the best restorative material to decrease microleakage is of great importance in operative dentistry. The aim of this study was to evaluate the effect of polishing time on the microleakage of three types of tooth-colored restorative materials in class V cavity preparations and to assess the marginal integrity of these materials using scanning electron microscope (SEM).
Materials and Methods: In this in vitro study, class V cavity preparations were made on the buccal and lingual surfaces of 30 bovine incisors (60 cavities). The specimens were divided into three groups each containing 10 teeth (20 cavities): group 1, Filtek Z350 (nanocomposite) group 2, Fuji IX/G Coat Plus (CGIC) and group 3, Fuji II LC (RMGI). In each group, half of the specimens (n = 20) were finished/polished immediately and the rest of them were finished/polished after 24 hours. All the specimens were thermocycled for 2000 cycles (5-50 °C). Epoxy resin replicas of 12 specimens (2 restorations in each subgroup) were evaluated using SEM and the interfacial gaps were measured. Finally, the teeth were immersed in 0.5% basic fuchsin dye for 24 hours at room temperature, sectioned and observed under stereomicroscope. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests and the comparison between incisal and cervical microleakage was made with Wilcoxon test.
Results: Incisal and cervical microleakage were not affected by polishing time in none of the three restorative materials (P>0.05). Cervical microleakage only in Fuji IX with immediate polishing was significantly higher than incisal microleakage (P<0.05). Incisal and cervical microleakage with immediate or delayed polishing were not significantly different in Fuji IX, Fuji II LC, and Z350 (P>0.05).
Conclusion: Immediate polishing is recommended in tooth-colored class V restorations.

Background and Aims: A large number of investigations have revealed that physical and chemical alterations and weight loss could occur in composite materials exposed to acidic phosphate fluoride (APF) gel. The purpose of this study was to assess the microleakage of a fissure sealant and a flow composite exposed to acidulated phosphate fluoride (APF) gel.

Materials and Methods: In this in vitro study, 60 intact human extracted premolar teeth were used. After preparing the occlusal groove, the teeth were divided into two groups (n=30). Teeth were filled with either Helioseal fissure sealant (Vivadent, Germany) or Tetric flow composite (Vivadent, Germany). After that, each group was divided into two subgroups (n=15): 1.23% APF gel (Sultan, U.S.A) was applied in the case subgroups, while control subgroups were preserved in normal saline solution. All of teeth were covered with 2 layers of nail varnish except for the filling zone and 1mm around the border of filling. After submerging in 0.5% fushin solution, specimens were sectioned bucco-lingually. Then dye penetration through the filling and fissure sealant was assessed by means of a stereo-microscope. The depth of dye penetration was scored. The data were analyzed using One-way ANOVA and Levene test.

Results: The mean values of dye penetration were 1.26±1.09, 1.4±1.05, 1.2±1.37, and 1.4±1.35 for fissure sealant+gel, composite+gel, composite+normal saline, and normal saline groups, respectively. No significant difference was found in inter-groups (P=0.96).

Conclusion: Considering the result of the present research, APF gel had no significant effect on the microleakage of Tetric flow composite filling and Helioseal fissure sealant and thus, it can be applied for routine usage.

Background and Aims: The seal provided by a root canal filling may be compromised by post space preparation. The aim of this study was to compare coronal microleakage around cast posts and prefabricated pins.

Materials and Methods: Thirty-eight extracted single-rooted, maxillary human teeth were prepared with step back method and filled with gutta-percha and sealer. After removing 8 mm of coronal gutta-percha with peeso-reamer drills #2 in twenty canals, the teeth were divided into three groups: cast post & core, prefabricated pin,  and gutta-percha (without any post or pin). After thermocycling, the samples were immersed in India ink for seven days. Finally, the specimens were cleared and the coronal microleakage of dye was then measured by the stereomicroscope. The data were analyzed by One-way ANOVA and Tukey HSD tests.

Results: According to the results, the mean dye penetration in cast posts, pins, and group without post or pin was 3.3 (0.39), 5.2 (0.47), and 7.2 (0.15) mm, respectively. There was no statistically significant difference between the groups (P>0.05).

Conclusion: Considering the importance of adequate filling of crown for prevention of microleakage, the method for coronal filling must be selected with caution. According to the results of this study, no significant difference between microleakage of cast posts and prefabricated pins was observed.

Background and Aims: Composite restorative materials and dental adhesives are usually cured with light sources. The light direction may influence the bond strength of dental adhesives. The aim of this study was to evaluate the effect of light direction on the microtensile bond strength of fifth and sixth generation dental adhesives.

Materials and Methods: Prime & Bond NT and Clearfil SE bond were used with different light directions. Sixty human incisor teeth were divided into 4 groups (n=15). In groups A and C, Clearfil SE bond with light curing direction from buccal was used for bonding a composite resin to dentin. In groups B and D, Prime & Bond NT with light curing direction from composite was used. After thermocycling the specimens were subjected to tensile force until debonding occurred and values for microtensile bond strength were recorded. The data were analyzed using two-way ANOVA and Tukey post hoc test.

Results: The findings showed that the bond strength of Clearfil SE bond was significantly higher than that of Prime&Bond NT (P<0.001). There was no significant difference between light curing directions (P=0.132).

Conclusion: Light curing direction did not have significant effect on the bond strength. Sixth generation adhesives was more successful than fifth generation in terms of bond strength to dentin.

Background and Aims: The aim of this study was to evaluate the quality of an experimental hydrofluoric acid (HF) for preparation of porcelain and to compare it with two commercial hydrofluoric acids in Iranian trademark.

Materials and Methods: A- Evaluation of etch pattern of experimental HF using scanning electron microscope (SEM): 6 feldespathic discs were divided into 3 groups. Each group was etched with related HF (experimental, Ultradent and Kimia) for 1 minute. SEM images were recorded at 3 magnifications. B- Bond strength test: 18 feldespathic discs were considered for each acidic group. Then the porcelain surfaces were etched and bonded to composite with unfilled resin. Consequently, the microshear test was done. C- Microleakage test: 54 discs were divided into 3 groups (n=18). Then the porcelain surfaces were etched and bonded to composite with unfilled resin and finally observed under stereomicroscope. The data were analyzed with one-way ANOVA and Smirnov tests.

Results: SEM analysis showed no difference between groups in terms of etch pattern. Microshear bond strength values for experimental, Kimia, and Ultradent HF were 28.53 (±4.92), 28.21 (±6.61), and 26.14 (±7.61) MPa, respectively. There was no significant difference between the bond strength of test groups (P<0.05). Furthermore, no significant difference was found between the microleakage of test groups (P>0.05).

Conclusion: Quality of experimental HF in terms of etch pattern, microshear bond strength and microleakage of composite/porcelain interface was similar to that of two commercial hydrofluoric acids.

Background and Aims: The aim of the present study was to investigate self-perceived need to learn practice management and self reported knowledge in this regard among dentists.

Materials and Methods: A group of five academic staff members of Community Oral Health Department (Tehran Dental School) and four dentists formed an expert panel to develop the content of the course. This group developed a list of topics related to principles of successful dental practice. To investigate the necessity of educating the topics and self-assessed knowledge of the topics, a questionnaire was designed and administered to 55 volunteer dentists. Forty six dentists completed the questionnaire. T-test and Chi-square test were used for statistical analyses.

Results: Totally more than two-third of the dentists believed that a huge need exists for education of all the topics. The corresponded figure for such topics as ergonomics and medical emergencies was about 90%. About 80% of the dentists felt that they had a vast knowledge of safety and infection control. On the other hand, 54.3% of them reported weak knowledge regarding professional rules and regulations. Self-reported educational need and knowledge of the dentists did not show significant association with their age, gender, and work experience
(P>0.05).

Conclusion: The dentists believed in the necessity of educating such topics and evaluated their knowledge as deficient in these areas. This shows the necessity of developing courses on these topics.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. Surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.

Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.

Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005). There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).

Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

Background and Aims: Using the conservative adhesive resin restoration (CAR) in uncooperative children lead to numerous problems because of being time consuming. The purpose of this study was to compare the microleakage of conservative adhesive resin restoration under separate curing and co-curing.

Materials and Methods: In this experimental study, 120 intact premolar teeth were collected and 120 vertical grooves were prepared on them. Then the teeth were divided into four groups: group 1, separated curing of bonding agent, flowable composite and sealant group 2, co-curing of all materials for 60 seconds group 3,
co-curing of all materials for 40 seconds and group 4, co-curing of all materials for 20 seconds. Then the specimens were thermocycled and immersed in basic fuchsin solution. The teeth were sectioned horizontally and dye penetration was evaluated with stereomicroscope. Date were analyzed using one-way ANOVA and Scheffe test.

Results: Mean value of dye penetration in groups 1, 2, 3, and 4 was 1.53±0.6, 2.06±0.6, 2.5±0.7 and 3.53±0.6, respectively. There was a statistically significant difference between group 1 and the other groups (P=0.0001).

Conclusion: Considering the problems caused by microleakage in conservative resin adhesive restorations, co-curing method should not be used. In the case of using co-curing method, 60 second curing time is suggested for sufficient polymerization.

Background and Aims: The aim of this in vitro study was to assess the shear bond strength of amalgam to dentin using four dentin adhesive systems.
Materials and Methods: One hundred human molars were selected. After enamel removal, a dentin cylinder with 3 mm thickness was prepared. Eighty specimens were resorted with amalgam and four dentin adhesive systems as follows (n=20): group 1, Scotch Bond Multi-Purpose group 2, One Coat Bond group 3, PQ1 and group 4, Panavia-F. In group 5, 20 specimens were resorted with amalgam and varnish as control group. The specimens were incubated at 37°C for 24 h. The shear bond strengths were then measured by using push out method. The data were analyzed by one-way ANOVA and post hoc Duncan's tests.
Results: Mean values for bond strengths of test groups were as follows: group 1=21.03±8.9, group 2=23.47±9, group 3=13.16±8.8, group 4=20.07±8.9 and group 5=14.15±8.7 MPa±SD. One-way ANOVA showed the statistically significant difference between the bond strengths of five groups (P=0.001). Post hoc Duncan's test showed significant difference between groups 1and 3 (P=0.008), groups 1 and 5 (P=0.019), groups 2 and 5 (P=0.0008), groups 4 and 5 (P=0.042), and groups 3 and 4 (P=0.018).
Conclusion: Results of this study showed that the bond strength of amalgam to dentin using One Coat Bond as dentin adhesive system was higher than that observed in other dentin adhesive systems.

Background and Aims: Although composite resin restorations have many advantages, they can lead to several clinical problems. The primary reason for these problems is microleakage. The aim of this study was to compare the rebonding effect on microleakage of class V composite restorations using two low viscosity resins.
Materials and Methods: In this in vitro study, 60 class V composite restorations were performed in buccal and lingual surfaces of human extracted premolars with the occlusal margin in enamel and the gingival margin in dentin/cementum. The teeth were randomly divided into 3 groups: (I) restorations with no rebonding, (II) restoration margins rebonded with an enamel adhesive (Margin Bond), (III) restoration margins rebonded with a specific unfilled resin. The specimens were then thermocycled and immersed in 0.5% fuchsin dye solution. The samples were sectioned longitudinally and observed under a stereomicroscope for assessment of microleakage. The data were analyzed by Kruskal-Wallis, Wilcoxon and Mann-Whitney tests. P<0.05 was considered as the level of significance.
Results: Statistical analysis showed a significant difference in the microleakage of gingival margins (P<0.0001), but not in enamel margins (P=0.148). Microleakage at the gingival margins of group (III) was significantly less than that of group (II). Group (I) showed the highest amount of microleakage.
Conclusion: Rebonding by a low viscosity resin reduces microleakage at the gingival margins of class V composite restorations, but has no significant effect on the occlusal margins.

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 Aims: The purpose of this study was to evaluate the sealing ability of different thicknesses of orthograde MTA plugs in comparison with 5 mm gutta-percha.

Materials and Methods: Fifty extracted single rooted human teeth were collected. After root canal preparation, the samples were randomly divided into 4 experimental (n=10) and two control groups (n=5). In group 1, the apical 5 mm of the canals were obturated using laterally condensed gutta-percha and sealer AH26. Groups 2, 3 and 4 received 2, 3 and 4-mm thick orthograde MTA plug, respectively. Thereafter, the coronal portion of specimens was exposed to the microbial solution containing streptococcus sanguis and the root tips were placed in phenol red lactose broth. The color changes were observed within 60 days. The data were analyzed with Fisher exact test.

Results: The leakage was found in all samples (100%) in group 1 and 72.7%, 30.8% and 50% of the samples in groups 2, 3 and 4, respectively. Significant difference was found between 3 mm thickness of MTA plug and gutta percha and sealer (P=0.02).

Conclusion: According to the findings, it seems that 3 mm thickness of orthograde MTA plug had better sealing ability than the other thicknesses of MTA plug as well as the 5 mm of gutta-percha.