Journal of Dental Medicine

Background and Aim: Sealing the root canal system is of great importance in endodontic treatment especially in infected teeth. Several materials have been introduced for this purpose. The aim of the present study was to evaluate the sealing ability of MTA as an orthograde root filling material and compare it with laterally condensed gutta-percha with sealer.

Materials and Methods: Thirty-six extracted human maxillary central and canine teeth were used in this experimental study. After preparation and surface disinfection with 1% NaOCl solution, the crowns of the teeth were cut at cemento-enamel junction.Roots were randomly divided into four groups: two experimental groups  of 15 roots each (gutta-percha with AH26 sealer and MTA) and two control groups of 3 roots each (positive and negative). After root canal preparation and filling, the sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 72 hours. Then the teeth were cleared and the extent of dye penetration was measured with a stereomicroscope. Data were analyzed by T-test with P<0.05 as the level of significance.

Results: The results showed that the mean microleakage was 1.1mm (SD=2.1) in the gutta percha group and 3.4mm (SD= 2.1) in the MTA group.This difference was statistically significant (P=0.013).

Conclusion: Based on the results of this study, canal obturation with gutta-percha and AH26 sealer may provide a better apical seal compared with MTA. However, further studies on microbial leakage are needed for more precise evaluation of the sealing ability of MTA.

Background and Aim: Because of polymerization shrinkage and high viscosity of posterior composites, there are some difficulties in using them in posterior restorations. Several methods have been represented to reduce the effect of shrinkage. The aim of this study was to investigate the effect of curing flowable composites under condensable ones in adaptation and microleakage reduction of posterior composite restorations.

Materials and Methods: In this experimental in vitro study, forty class II MO cavities were prepared on extracted intact molar and premolar human teeth. Gingival margins were placed 1 mm apical to CEJ. The teeth were divided into two groups. In group 1, flowable composite (Filek Flow, 3M, ESPE, USA) with 0.5-1 mm thickness was applied and cured following application of bonding agent (Single Bond, 3M, ESPE, USA). The rest of the cavity was filled by condensable composite (p60, 3M, ESPE, USA). In group 2 the flowable composite was not cured, and the condensable composite was applied in two increments. After light curing of composites, all the specimens were thermocycled and then immersed in 0.3% basic fuschin. Specimens were sectioned and evaluated for degree of dye penetration under a stereomicroscope. Data were analyzed by Mann-Whitney test with p<0.05 as the level of significance.

Results:. There was no significant difference between the two studied groups regarding microleakage.

Conclusion: Based on the results of this study, neither cured nor uncured flowable composite under condensable composite can omit microleakage in posterior composite restorations.

Background and Aim: The use of proper temporary restorative materials between appointments is critical in successful root canal treatment. The purpose of this study was to compare the coronal microleakage of four temporary restorative materials including Zonalin, Zamherir, Coltosol and IRM.

Materials and Methods: In this in vitro study, standard access cavities were prepared in 120 intact extracted maxillary and mandibular human first molars. Canal preparation was carried out by the step-back technique, and obturation was performed with gutta-percha and AH26 sealer using the lateral condensation technique. Teeth were randomly divided into 4 experimental groups of 25 teeth each and two positive and negative control groups, each containing 10 teeth. In each experimental group the access cavity was restored with one of the tested materials (Zamherir, Zonalin, IRM and Coltosol). In the negative control group the access cavity was filled entirely with sticky wax and in the positive control group no restorative material was applied. Dye penetration technique was used to evaluate microleakage which was measured under a stereomicroscope. Data were analyzed with one way ANOVA and post hoc Tukey tests. P<0.05 was considered as the limit of significance.

Results: Dye penetration was observed in all groups. Zonalin and Coltosol had the highest and the lowest dye penetration respectively, with a statistically significant difference (p<0.001). There was no significant difference in dye penetration between IRM, and either Coltosol or Zamherir (p>0.05).

Conclusion: The results of this study showed that using Coltosol as a temporary restorative material can provide a better coronal seal in endodontic treatments

Background and Aim: Application of varnish and dentin bonding agents can effectively reduce microleakage under amalgam restorations. Also rebonding may show some effects on microleakage and its complications. The aim of this study was to evaluate the effect of liner/ adhesives on microleakage of Class V amalgam restoration with or without rebonding.

Materials and Methods: In this in vitro study Class V cavities were prepared on sixty sound human maxillary premolars with the gingival floor 1mm below the CEJ. Cases were divided into six groups of ten teeth each. Specimens in group 1 and 2 were lined with Copalite and Scotchbond Multi-Purpose (SBMP) respectively. In the third group (control) no liner was applied. The teeth were then restored with spherical amalgam. Specimens in group 4 to 6 received the same treatments but after filling, the interfaces of restorations and teeth were etched with 37% phosphoric acid gel, rinsed and dried. Adhesive resin of SBMP was applied over amalgam and tooth margins and polymerized (rebonding). Specimens were thermocycled, exposed to dye and sectioned. Microleakage was graded (0-3) using a stereomicroscope at X40 magnification. Data were analyzed with Kruskal-Wallis, Mann-Whitney and Wilcoxon pair wise statistical tests. P<0.05 was considered as the limit of significance.

Results: The groups lined with SBMP showed the lowest and the groups without liner the highest microleakage (p= 0.001). Significant difference was observed in microleakage mean rank of enamel and dentin margins (p=0.048). Rebonding with resin did not improve the seal (p> 0.05).

Conclusion: Based on the results of this study, total etch adhesive system had significant effect on microleakage of Class V amalgam restorations especially in cervical margin. Rebonding did not show a significant effect on microleakage.

Background and Aim: Pit and fissure sealant therapy, is one of the most effective methods, in prevention of occlusal caries. Saliva contamination before curing the resin can increase the risk of failure in this method. The purpose of this study was to evaluate the effect of saliva contamination prior to curing on microleakage of pit and fissure sealants.

Materials and Methods: In this experimental in vitro study 21 sound human pre molars were selected and two standardized V-Shaped fissures were prepared on both buccal and lingual surfaces, then they were randomly divided into two equal groups. In the control group, the sealant was cured without any saliva contamination and in the case group, the sealed teeth were immersed in artificial saliva for ten seconds before curing. After thermocycling the samples were immersed in 2% fouchsin solution for 24 hours and then sectioned longitudinally in bucco - lingual direction. The specimens were then fixed and assessed under stereomicroscope to determine microleakage and dye penetration using paired student t. test. P<0.05 was considered as the level of significance.

Results: Analysis of data showed no significant differences in microleakage, between the two groups (p=0.178).

Conclusion: According to the results of this study saliva contamination of uncured sealant had no influence on microleakage.

Background and Aim: Microleakage has been always a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. The aim of this study was to investigate the effect of flowable and dual-cure resin composite liners on gingival microleakage of packable resin composite restorations.

Materials and Methods: Sixty Class II cavities with cervical margins 1 mm below the CEJ were prepared in 30 extracted human molars. The teeth were randomly divided into five groups of 12 each. In control group, each tooth was restored incrementally with Tetric Ceram composite without applying any liner. In the second and forth groups, flowable materials- Tetric Flow and dual-cure composite resin cement Relay X ARC were placed respectively as a 1-mm thick gingival increment and cured before the resin composite restoration, whereas, in the third and fifth groups liners were cured with the first increment of packable composite.The restored teeth were stored for one week in distilled water at 37⁰C, and thermocycled between 5⁰C and 55⁰C, sealed with nail varnish except the tooth - composite interface in cervical restoration margins and immersed in 2% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope with 28x magnification. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests with p<0.05 as the level of significance.

Results: The results of this study indicated that there were significant statistical differences between control - cured flowable liner, control-flowable liner without separately curing, control-cured dual cure composite resin cement groups.However there were no significant differences between dual-cure composite resin cement without separately curing-control,cured flowable liner-cured dual cure composite resin cement, flowable liner without separately curing-dual cure composite resin cement without separately curing groups.

Conclusion: The results of this study indicated that none of techniques could thoroughly eliminate microleakage in gingival floor, however the effect of flowable or a dual-cure liner on reducing the gingival microleakage was found to be statistically significant in tested restorative material.

Background and Aim: Amalgam is one of the mostly used restorative materials, but has some disadvantages. Microleakage is one of the short comings of amalgam which may lead to sensitivity and recurrent caries. The aim of this study was to evaluate the effect of three dentin bonding systems on reduction of microleakage in amalgam restorations.

Materials and Methods: Class II amalgam restorations were made in 40 noncarious molar and premolar teeth. Then the specimens were divided into four equal groups. Scotch Bond Multi Purpose, Single bond,
iBond, were used as liner in groups one to three respectively and in group four no liner was used. The teeth were restored with high copper spherical amalgam. After thermocycling for 500 cycles at 5⁰C and 55⁰C, the specimens were immersed in basic fuchsin for 24 hours, bisectioned mesiodistally and evaluated under stereomicroscope at X25 for dye penetration. The data were analyzed by Kruskal-wallis and Scheffe. P<0.05 was considered as the level of significance.

Results: The groups showed significant difference (p=0.003). The group four had significantly less microleakage than the first and second groups (p<0.05). The second and third groups showed significantly different microleakage (p=0.038).

Conclusion: Based on the results of this investigation applying dentin bonding agents has no effect on reducing microleakage in amalgam restorations, however more studies are recommended.

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 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: 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: 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.

Background and Aims: Marginal seal in class V cavity and determination of the best restorative material in reducing microleakage is of great concern in operative dentistry. The aim of this study was to evaluate the effect of load cycling on the microleakage of low shrinkage composites compared with methacrylate-based composites with low shirinkage rate in class V cavity preparation. Marginal integrity of these materials was assessed 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 48 human premolars and molars (96 cavities). The specimens were divided into four groups each containing 12 teeth (24 cavities): group 1 (Kalore-GC+ G-Bond) , group 2 (Futurabond NR+Grandio), group 3 (All Bond SE+ Aelite LS Posterior), group 4 (LS System Adhesive Primer & Bond+Filtek P90). All the specimens were thermocycled for 2000 cycles (5-50^oC). In each group, half of the specimens (n=12) were subjected to 200,000 cycles of loading at 80 N. Epoxy resin replicas of 32 specimens (4 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 37⁰C, then sectioned and observed under stereomicroscope. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests and the comparison between occlusal and gingival microleakage was made with Wilcoxon test.

Results: Within unloaded or loaded specimens, there were no significant differences in microleakage among four groups on the occlusal margins (P>0.05). But there were statistically significant differences in microleakage between silorane and Aelite on the gingival margins (P<0.05). No statistically significant differences were found between the microleakage of the loaded and unloaded groups on both occlusal and gingival margins for all materials (P>0.05).

Conclusion: Silorane did not perform better than the conventional low shrinkage methacrylate-based composite in terms of sealing ability (except Aelite). Cyclic loading did not increase the extent of leakage in any groups.