In Vitro Microleakage Comparison of Flowable Nanocomposites and Conventional Materials Used in Pit and Fissure Sealant Therapy

Comparative evaluation of microleakage and penetration depth of ACP containing pit and fissure sealant and flowable composite - An in-vitro study

Background

The present in vitro study evaluated and compared the microleakage and penetration depth of ACP containing pit and fissure sealant with flowable composite.

Material and Methods

Sixty extracted non-carious premolars were categorized into four groups of 15 samples each. Sealant was applied after the Occlusal surfaces of the sample teeth were prophylactically treated with pumice slurry. Later, the teeth were thermocycled and immersed in methylene blue for a period of 24 hours. The samples were buccolingually sectioned and analysed under a stereomicroscope. Statistical analysis was carried out to compare the microleakage and depth of penetration.

Results

Flowable nanocomposite gave comparable results with that of the sealant in terms of microleakage. Nano-hybrid flowable composite performed better with respect to depth of penetration between tested materials with the difference being statistically significant.

Conclusions

Flowable nanocomposite can be considered as a promising substitute for sealing fissures and thus can be endorsed to caries susceptible pediatric patients. Key words:Depth of Penetration, Sealants, Microleakage.

Comparison of Retention between Conventional and Nanofilled Resin Sealants in a Paediatric Population: A Randomized Clinical Trial

Background: This study compared conventional-resin-sealant versus nanofilled-sealant retention at different intervals. Methods: A double-blinded split-mouth randomized control trial was performed on sixty-two children aged from six to nine years. Participants with one pair of contralateral permanent first molars with deep fissures or noncavitated carious lesions were randomly selected for sealant application. Conventional resin sealant was applied on one molar and nanofilled sealant on the contralateral molar. Evaluations were performed at one, three, six, twelve and eighteen months to check for retention. The chi-squared test, McNemar test, Wilcoxon signed-rank test and Friedman test were used for statistical analysis. Results: Conventional resin sealant showed complete retention in 91.4%, 86.2%, 74.1%, 62.1% and 55.2% of the teeth, and nanofilled sealant showed complete retention in 89.7%, 81%, 77.6%, 69% and 67.2% of the teeth, at the end of 1 month, 3 months, 6 months, 12 months and 18 months evaluation, respectively. Each sealant exhibited a statistically significant change (p < 0.05) in the retention rate during the evaluation period. However, when both the sealants were compared with each other, there was no statistically significant difference in any phase. At the end of 18 months, caries development was observed in 13.8% of the teeth sealed with conventional sealant, and in 10.3% of the teeth sealed with nanofilled sealant. Conclusion: At eighteen months, the nanofilled resin sealant exhibited complete retention in 12% more teeth than the conventional sealant. However, the difference was not statistically significant. The nanofilled resin sealant yielded an acceptable performance in sealing the occlusal pits and fissures of mandibular permanent first molars, compared to conventional pit-and-fissure sealants.

Microleakage Evaluation of Expired and Non-expired Resin Composites and Bonding Agents: In Vitro Study

Aim:

Although the shelf life is a key property of dental composites and bonding agents, these materials may often be used in simple procedures after expiration. In this study, the microleakage of two year expired and non-expired dental composites (Filtek Ultimate Universal A2 Enamel, 3M ESPE, USA, and Tetric N Ceram A2, Ivoclar Vivadent, Schaan, Liechtenstein) and a universal bonding system (Single Bond Universal, 3M ESPE, USA) was examined.

Materials and Methods:

In 40 freshly extracted human molars, two standardized Class II cavities (buccolingual and mesiodistal width of 3 mm and 4 mm, respectively) were prepared (80 cavity preparations). The teeth were thermocycled in distilled water for 1000 cycles in a 5°C to 55°C water bath. Next, the teeth and their apical foramens were coated with water resistant nail varnish, except for 1 mm around the restoration–tooth interface, and retained in a 1% methylene blue solution. After 24 h, the specimens were cut into two halves and analyzed using a stereomicroscope. Scanning electron microscopy images of two samples of the groups were obtained.

Results:

The Kruskal–Wallis test indicated no significant differences between the groups ( P < .05). The occlusal median scores were not significant ( P = .99). Moreover, the gingival median scores were not significant ( P = .48). No difference was found between the occlusal and gingival values in any group ( P > .05).

Conclusion:

These findings indicated that two-year-expired dental composites and bonding agent, which were maintained under proper conditions, do not have any significant difference in terms of the microleakage.

Lingual retainer materials: Comparative evaluation of wear resistance of flowable nanocomposites and universal composite: An in vitro study

BACKGROUND

A bonded fixed retainer is used to stabilize the alignment of the teeth. Different composites have been introduced for this purpose. This study aimed to investigate the wear resistance of flowable nanocomposite in comparison with microhybrid composite in an in vitro situation.

MATERIALS AND METHODS

In this in vitro study, 46 disk-shaped specimens were divided into two groups: Filtek Ultimate flowable composite and Z250 microhybrid composite. The samples were prepared in 8 mm diameter and 3 mm thickness in an aluminum mold and light cured. They were polished with 600 grit sandpaper to achieve a smooth surface. Two-body wear test was accomplished by the pin-on-disk device (under 15 N, 20 rpm for 1 h). Analyzing the weight and thickness of specimens before and after the assay demonstrates the wear resistance. Data were analyzed using the t-test. P ≤ 0.05 was considered statistically significant.

RESULTS

The Filtek Ultimate flowable composite shows no significant difference compared to Z250 microhybrid composite in thickness (P = 0.701) and weight (P = 0.939) of specimens.

CONCLUSION

Due to wear resistance of both materials, flowable composite can be recommended as an alternative material for bonded fixed retainers.