Comparison of the microleakage between two different flowable composite resin restorations with 8th generation bond system in Class II cavity - An in vitro stereomicroscopic study.
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-12-31 |
| Journal | University Journal of Dental Sciences |
| Authors | Kaushal Kishor Singh, Amit Garg, Rajnish K Singhal, Anurag Jain, Neha Agarawal |
| Institutions | Maharana Pratap University of Agriculture and Technology, American Association of Endodontists |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study investigated the marginal integrity of two flowable bulk-fill composite resins in Class II restorations, focusing on microleakage performance under simulated aging conditions.
- Core Value Proposition: Comparison of Smart Dentin Replacement (SDR) versus Tetric Evo Flow Bulk Fill, demonstrating the superior sealing ability of SDR when used with an 8th generation universal adhesive (Futurabond DC).
- Key Achievement: SDR exhibited the minimum microleakage (mean score 0.4 ± 0.83), significantly outperforming Tetric Evo Flow Bulk Fill (mean score 0.75 ± 1.118).
- Methodology: Microleakage was quantified using 2% methylene blue dye penetration after subjecting the restored teeth to 1500 cycles of thermocycling (5 °C to 55 °C).
- Interface Performance: Restorations placed above the cementoenamel junction (CEJ) consistently showed better marginal sealing than those placed below the CEJ, highlighting the critical role of enamel as a bonding substrate.
- Material Science Implication: The results support the use of flowable composites with low polymerization stress (like SDR) as a base layer to enhance marginal adaptation and reduce gap formation in deep cavities.
- Statistical Finding: While SDR showed lower mean leakage, the difference between the two materials and between placement locations (above vs. below CEJ) was statistically insignificant (p > 0.05).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Cavity Dimensions (Width) | 4 | mm | Buccolingual width of Class II preparation |
| Cavity Dimensions (Depth) | 2 | mm | Pulpal depth of Class II preparation |
| Thermocycling Cycles | 1500 | cycles | Artificial aging protocol |
| Thermocycling Temperature Range | 5 ± 2 and 55 ± 2 | °C | Water bath immersion temperatures |
| Thermocycling Dwell Time | 30 | sec | Time spent at extreme temperatures |
| Dye Penetration Medium | 2 | % | Methylene Blue solution |
| Stereomicroscope Magnification | 25 | X | Observation and scoring of sections |
| SDR Mean Microleakage (Group Ia) | 0.4 ± 0.83 | Score (0-4) | Flowable placed above CEJ (Minimum Leakage) |
| Tetric Evo Flow Mean Microleakage (Group IIa) | 0.75 ± 1.118 | Score (0-4) | Flowable placed above CEJ (Highest Leakage) |
| Tetric Evo Flow Filler Content | 76-77 | % weight | Inorganic fillers (Barium glass, Ytterbium trifluoride) |
| Tetric Evo Flow Monomer Content | 20-21 | % weight | Dimethacrylates |
| Bonding System Type | Self-etch | N/A | Futurabond DC (8th generation universal adhesive) |
Key Methodologies
Section titled âKey Methodologiesâ- Specimen Acquisition and Preparation: Forty non-carious extracted mandibular molars were collected. Standardized Class II box type cavities were prepared (4 mm buccolingual width, 2 mm pulpal depth) using a high-speed air rotor and a straight fissure diamond bur.
- Grouping and Restoration: Teeth were divided into Group I (SDR) and Group II (Tetric Evo Flow Bulk Fill). Both groups utilized Futurabond DC adhesive. Restorations were placed using a bulk-fill technique (up to 4 mm increments) and light-cured for 20 seconds.
- Substrate Variation: Groups were subdivided (Ia/Ib and IIa/IIb) based on whether the flowable composite was applied above or below the cementoenamel junction (CEJ) to test substrate influence (enamel vs. dentin margin).
- Artificial Aging (Thermocycling): Specimens were stored in distilled water (24 hours at 37 °C), then subjected to 1500 cycles of thermal stress between 5 °C and 55 °C, with a 30-second dwell time per bath.
- Dye Penetration Protocol: Teeth were sealed at the apices and coated with fingernail polish, leaving a 1 mm margin exposed. Specimens were immersed in 2% methylene blue dye for 24 hours.
- Microleakage Assessment: Teeth were sectioned mesiodistally. Dye penetration depth at the cervical and axial walls was scored (0: No penetration to 4: Penetration toward the pulp) using a stereomicroscope at 25X magnification.
Commercial Applications
Section titled âCommercial ApplicationsâThe findings relate directly to the engineering and material selection challenges in high-performance composite systems, particularly where minimizing interfacial stress and maximizing long-term durability are critical.
- Advanced Polymer Composites: Utilization of bulk-fill flowable resins (SDR) designed with proprietary stress-relieving monomers, enabling placement in 4 mm increments while maintaining low polymerization shrinkage stress.
- Interface Engineering and Adhesion: Selection and validation of 8th generation universal adhesives (Futurabond DC) for achieving reliable hybrid layer formation and bonding strength across heterogeneous substrates (enamel, dentin, cementum).
- Durability and Lifetime Prediction: Implementation of rigorous thermal fatigue testing (1500 thermocycles) as a standard quality assurance measure to predict the long-term marginal integrity and failure modes of composite materials under thermal cycling.
- Stress Mitigation Layers: Commercial application of low-viscosity, high-elasticity flowable materials as intermediate layers to absorb polymerization shrinkage stress from overlying high-viscosity composites, thereby preventing gap formation.
- Biomaterials Development: Focus on optimizing filler chemistry (e.g., Barium glass, Ytterbium trifluoride) to ensure adequate radiopacity and mechanical properties while maintaining biocompatibility.
View Original Abstract
Introduction Marginal adaptability of composite resins is one of the prime factors for the success of class II cavity restoration. Materials and Methodology: Forty non-carious extracted mandibular molar with fully formed apices were collected and Class II box type cavities were prepared on both mesial and distal surfaces of every tooth using a new straight fissure diamond bur and high-speed airrotor handpiece. According to the type of restorative materials used, teeth were divided into Group I (n=20): Restored with SDR (Smart Dentin Replacement) and Group II (n=20): Restored with Tetric Eva Flow Bulk Fill. After 24 hours of storage in distilled water at 37ËC, the restored specimens were subjected to artificial aging by thermocycling. The teeth were then immersed in a 2% methylene blue dye for 24 hours. All samples were cut longitudinally through the center of the restorations with the help of an isomet diamond saw. The sections were then observed under a stereomicroscope at 25X for scoring the depth of dye penetration at cervical and axial walls toward the pulp. Results: Mean score of Group Ia is 0.4±0.83 and Ib was 0.55±0.88 respectively while the mean score of Group IIa was 0.75±1.118 and in IIb was 0.75±1.019 respectively. Microleakage was found to be highest in Group IIa and minimum in Group Ia. Conclusion: Use of a flowable composite SDR above and below the CEJ in Class II composite resin restorations showed good results.