An In vitro Evaluation of Microleakage Associated with Three Different Compomer Placement Techniques in Primary Molars

Utility of Dental Operating Microscopes in Assessing Microleakage of Nanohybrid Resin Restorations Using Different Placement Techniques

Background

Composite resin has become a material of choice due to its aesthetic potential and durability. It is at a lower cost compared to ceramic restorations. But it has a tendency to shrink during polymerization, leading to the formation of gaps at the margins. Placement techniques of restoration can be modified to reduce stress shrinkage. A dental operating microscope will help in the precise and thin layering of composite against the cavity wall and the matrix band.

Methodology

Class I cavities were prepared in 30 human permanent premolars. All cavity surfaces were dried and acid-etched. A bonding agent was applied and they were light-cured. Specimens were divided into three groups: I, II, and III, where restorations were performed using horizontal layering, oblique layering, and split-increment horizontal layering techniques respectively. Samples were then submerged in silver nitrate solution and were examined under a stereomicroscope after a longitudinal section and graded for dye penetration.

Results

The dye penetration scores were subjected to a statistical analysis using Analysis of variance (ANOVA) with post hoc Tukey’s test with the statistical software Statistical Package for Social Sciences (SPSS version 12). The level of significance was set at 0.05 for all statistical inferences.

Conclusion

The split-increment horizontal layering technique under the dental operating microscope showed less microleakage when compared to other methods and is the preferred method for composite restorations.

Polymerization characteristics of colored compomers cured with different LED units

Aim:

Incomplete polymerization of a resin material used for dental restoration affects the properties of the restoration. We evaluated the structural and mechanical properties of three different colored compomers cured with three different LED units to observe the characteristic changes occurring in different matches.

Methods:

Polytetrafluoroethylene molds (5 mm in diameter and 2 mm in thickness) were used to prepare disk-shaped sample specimens. Nine sample groups (each of five specimens) were prepared, three each of different compomer resin colors (gold, berry, and silver). Samples were cured using three different LED units (Optima, VALO, and Demi Ultra), according to the manufacturers’ instructions. Microstructural properties of samples were characterized by determining the degree of curing using Fourier-transform infrared spectroscopy and by analyzing sample morphology under a scanning electron microscope. The Vickers hardness, compressive strength, and elastic modulus of the samples were measured to investigate their mechanical properties.

Results:

The degrees of curing decreased in the order of silver > berry > gold for all curing units. Conversely, gold compomers exhibited poorer mechanical values than the berry and silver counterparts. The Optima 10 unit yielded slightly higher degrees of curing than the other devices, followed by Demi Ultra and VALO light-curing units, respectively.

Conclusion:

The resin color affected the structural and mechanical properties of the compomers, possibly as a result of the complex interactions and relationships between the irradiation light and resin material, such as light absorbance and reflectance; thus, depending on the color as well as the curing protocol.