Journal of Dental Medicine

Background and Aims: One of the main disadvantages of light cured composite resin materials is polymerization shrinkage upon curing. This leads to the microleakage of restoration and finally failure of the restoration. The purpose of this study was to investigate the effect of two types of light curing devices with different modes on the microleakage of posterior composite filling in Cl II restorations.
Materials and Methods: In this experimental study, 30 extracted sound molar human teeth were collected. All specimens were randomly divided into 3 groups of ten: Standard LED irradiation, pulse curing LED irradiation and QTH irradiation. All samples were prepared with mesial and distal boxes and composite fillings were done with three different light curing patterns for 20 s. After thermocycling, the specimens were kept in 2% methylene Blue solution for 24 h for microleakage test. After sectioning, the samples were evaluated by a stereomicroscope. For data analysis one-way ANOVA and Kolmogorov-Smirnov were used. P<0.05 was considered statistically significant.
Results: The quantitative tests showed that there were no statistical difference between study groups (P>0.05).
Conclusion: The results showed that both light curing devices were effective and no significant difference between different modes of LED light curing device on microleakage of class II composite restorations was found.

Background and Aims: The purpose of this study was to evaluate the sealing ability of MTA and cold ceramic by using bacterial leakage method.
Materials and Methods: In this experimental study, fifty human single root extracted teeth were chosen. In group A, 20 teeth were filled with MTA and in group B, 20 teeth were filled with cold ceramic. Five teeth were used as a positive control (obturated using gutta-percha without sealer), and five teeth were used as negative control (obturated using gutta-percha with AH26 sealer and coated with two layers of nail varnish). A bacterial leakage model utilizing Enterococcus faecalis was used for evaluation of the sealing ability. The teeth were placed in test tubes, so that they formed two upper and lower compartments. The cultured bacteria in the upper chamber were in contact with the coronal area of the tooth. The root end was placed in the lower chamber containing sterile culture media. In this case, the filling of the root canal was only the communication path between the upper and lower chambers. In this method, the presence of turbidity in the lower chamber indicated that bacteria had penetrated through barrier and reached the medium. The leakage was measured. The acquired data was analyzed using Chi-square test.
Results: In group A (MTA), 7 samples and in group B (Cold ceramic), 4 samples should the leakage. In regarding the leakage, there was no statistically significant difference between MTA and cold ceramic. (P=0.288)
Conclusion: The results showed that the sealing ability of MTA and cold ceramic was similar as root filling materials.

Background and Aims: Microorganisms are the main cause of pulpal and periapical diseases. The most important failure factor is the lack of proper seals for the canal, resulting in microbial leakage. Therefore, the purpose of this study was to evaluate the sealing ability of ProRoot MTA and Bio MTA in canal obturation using fluid infiltration.
Materials and Methods: In this experimental study, 46 extracted mandibular premolar single canal teeth were used. After preparing and disinfecting the teeth with 3% sodium hypochlorite, their crowns were cut off from the cement-enamel junction. The teeth were then randomly divided into four groups: Group 1 (n=20) Bio MTA, Group 2 MTA ProRoot (n=20), negative and positive control groups, each of them contained 3 teeth. The preparation of teeth was performed using the step back method. The filled teeth were then evaluated by fluid filtration for leakage prevention. Data were analyzed by Mann-Whitney test and Tukey test (α=0.05).
Results: The results of statistical analysis showed that there was no significant difference between the MTA ProRoot and Bio MTA in sealing ability (P>0.05). That micro leakage is less in the Bio MTA group than in the ProRoot MTA group, but the difference was not significant.
Conclusion: This study showed that MTA ProRoot and Bio MTA can be used as appropriate canal filling materials.

Background and Aims: The aim of the present study was to evaluate the effect of applying hydrophobic resin after use of different generation of the bonding systems on nanoleakage.
Materials and Methods: 20 third molar teeth were selected. The teeth were randomly divided into 4 groups of 5, each was treated using the fourth, fifth, sixth, and seven generation of dentin bonding. Then, the crown of teeth was sectioned from the CEJ region and each specimen was divided into two halves with mesiodistal cut, one half for the application of dentin bonding without the addition of a hydrophobic resin, and the other for the same dentin bonding by the addition of a hydrophobic resin. Afterwards, the specimens were restotred by composites. After placement of specimens in silver nitrate, the amount of nanoleakage was evaluated by SEM. Data were analyzed using a repeated measurement statistical analysis (α=0.05).
Results: The use of hydrophobic resins decreased nanoleakage and range of variations in all groups (P<0.05). This reduction was greater for total-etch dentin bonding. Higher degree of nanoleakage occurred in total-etch dentin bonding in most evaluated areas. In general, Clearfil S³ bond showed the least percent of the nanoleakage.
Conclusion: All dentin bonding systems showed some degree of reduction in nanoleakage after hydrophobic layer application and the reduction was greater in Total-etch adhesives systems.

Background and Aims: The self-adhering composites were introduced to reduce the chair time and minimizing handling errors. They can be bonded micromechanically to the dental structure without the need for separate adhesive application. Since there is limited information about bonding performance of this type of composite, the aim of this study was to evaluate the microleakage of enamel and dentin margins compared to the conventional adhesive systems.
Materials and Methods: 30 intact premolars were selected and on their buccal and lingual surfaces, standardized class V cavities with the occlusal margin in enamel and gingival margin in dentin were prepared. Then according to the materials used, the specimens were randomly divided into three groups including: 1) Vertise flow, 2) SE bond + ValuxTM Plus, and 3) Single bond + ValuxTM Plus. After final polishing of the restorations, the specimens were subjected to 1000 thermal cycles of 5±2 and 55±2°C and after that dye penetration was examined by stereomicroscope. The collected data were statistically analyzed using Kruskal-Wallis test and Mann-Whitney test
Results: The lowest rate of the occlosal microleakage was related to group 2 (P<0.05) and there was no significant difference between groups 1and 3 (P=0.58). Also, no significant difference was found in the gingival microleakage among the three groups (P=0.23). On the other hand, in each group, the gingival microleakage was significantly higher than occlosal margins (P<0.05).
Conclusion: According to the results, sealing ability of self-adhering composite is comparable with that of the conventional adhesives.

Background and Aims: Adding nanoparticles to dental composite resins, could reduce bacterial adhesion and secondary caries. Thermocycling can resemble in-vitro conditions to the oral environment. The aim of this study was to determine the effect of thermocycling on the microleakage of a mixture of copper oxide nanoparticles and flowable composite.
Materials and Methods: In this in-vitro study, 88 premolar teeth were divided into eight groups based on the application of copper oxide nanoparticles with concentrations of 0.1% and 0.3% w/w and thermocycling by 0, 1000, 5000 and 15,000 cycles. The occlusal grooves of the teeth were sealed with the mixture of flowable composite and copper oxide nanoparticles, and the teeth were thermocycled. Next, the teeth were immersed in methylene blue 2% solution for 24 hrs and were cut and the microleakage was evaluated by a stereomicroscope (hp/USA). Data were analyzed using Kruskal-Wallis and Mann-Whitney tests at the significance level of 0.05.
Results: In the groups with 0.1 % copper oxide nanoparticles, the mean microleakage increased significantly with increasing the number of thermocycling rounds (P=0.032). The difference in the microleakage between the groups exposed to 0 and 15,000 termocycling was significant (P=0.019). However, thermocycling had no significant effect on the microleakage of groups with concentration of 0.3% (P=0.780). The specimens subjected to the 0, 1000, 5000 and 15000 thermocycling in two concentrations of copper oxide nanoparticles showed no significant difference in the microleakage.
Conclusion: In groups containing copper oxide nanoparticles with a concentration of 0.1%, the microleakage increased by increasing the number of thermocycling up to 15,000 cycles compared to the control group. However, this did not have significant effect for the concentration of 0.3% copper oxide nanoparticles.

Background and Aims: The need to use a highly effective sealer in order to create a complete seal along the canal is essential for the basic treatment of tooth roots. Therefore, the aim of this study was to investigate the sealing ability of cold ceramic and gutta-percha with sealer by applying the bacterial leakage and electrochemical method.
Materials and Methods: In this in-vitro experimental study, fifty human single-rooted teeth were selected and their crowns were cut from the cervical region. The canals were prepared and washed with 17% EDTA. Then the teeth were randomly divided into four groups: group 1 gutta-percha with AH26 sealer (Dentsply Detrey, Germany) (n=20), group 2 cold ceramic (Yazd, Iran) (n=20), negative and positive control groups which each consisted of 5 teeth. Samples were kept in an incubator at 37° C for 48 hrs. Two coats of nail polish were used for covering the root, except for the last 2 mm, and microleakage in the fillings was measured by the bacterial leakage and electrochemical methods. The microleakage of the two groups was statistically analyzed in the electrochemical technique by Student's t-test, and in the bacterial leakage method by Fisher's exact test.
Results: In bacterial leakage method, in the first group (gutta-percha) 7 samples (35%) and in the second group (cold ceramic) 3 samples (15%) had bacterial leakage, but no significant difference was observed between the two groups on different days (P>0.05). The mean microleakage based on the electrochemical technique in gutta-percha was significantly higher than that of cold ceramic (P=0.0001).
Conclusion: According to the lower microleakage values in the use of cold ceramic compared to gutta-percha, cold ceramic  can be used to fill root canals to reduce microleakage, although further studies are needed.