Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

The Influence of Posterior Class II Composite Restoration Location and Techniques on Marginal Sealing

Background/Objectives: The success of treatment and prevention for secondary caries hinges significantly on the techniques employed in Class II composite restoration. Additionally, the location of the restored tooth within the oral cavity has emerged as a potential factor determining the quality of the restoration. A comprehensive understanding of these interrelated variables is crucial for advancing the efficacy and durability of dental composite restorations. The aim of this study was to assess how various restoration techniques and the specific location of the tooth restoration in the oral cavity affect marginal sealing, verified by the gap created in the tooth-restoration interface. Methods: Sixty extracted human teeth that had been indicated for orthodontic extraction were collected and embedded into a custom-made holder that was located in one of the four quadrants of a laboratory phantom head. Class II resin composite restorations, using flowable and packable composites, were performed on all teeth using two techniques: Pre-cure and Co-cure. The aging of the restored teeth was conducted using cyclic loading and thermocycling. After aging, the teeth were examined under a scanning electron microscope to measure the gap within the tooth-composite interface. Kolmogorov-Smirnov tests were used to assess the data distribution. Unpaired T-tests were employed to compare the mean gaps between the Pre-cure and Co-cure techniques. Additionally, unpaired T-tests were utilized to compare the mean gaps between the mesial and distal parts of the teeth. The Kruskal-Wallis test was used to compare the mean gaps among the four quadrants. The statistical significance was set at p = 0.05. Results: No significant difference in the gaps between the Pre-cure and Co-cure techniques was found (p = 0.212). The tooth's location did not generally affect the restoration's gap interface (p = 0.136). Conclusions: Flowable composites aid in restoring the deep margins of Class II composite restoration. Thus, the potential for further microleakage is similar for both the Pre-cure and Co-cure restoration techniques. The marginal seal of Class II composite restorations is effective when using both Pre-cure and Co-cure techniques, and the restoration site within the oral cavity does not significantly influence the tooth-composite interface seal.

Microleakage Evaluation of Two Methacrylate-Based Composites (GC Kalore and Luna SDI) in Class II Restorations: A Laboratory Study

OBJECTIVE

In recent years, dental composite resins such as tooth-colored restoration are frequently used to restore dental cavities, coronal fractures, and congenital defects. This study aimed to evaluate the microleakage of two methacrylate-based composites (GC Kalore and Luna SDI) in class II restorations.

MATERIALS AND METHODS

In this experimental study, a total of 18 intact human premolars previously extracted for periodontal and orthodontic reasons were randomly divided into two groups. Similar class II cavities (box only) were prepared on all teeth and restored with two different composites. In group 1, a bonding agent (Single Bond 2-SB2; 3M ESPE) and Luna SDI composite in mesial cavities and GC Kalore composite in distal cavities were used. In group 2, Single Bond 2 and GC Kalore composite in mesial cavities and Luna SDI composite in distal cavities were applied. They were then subjected to 2000 thermal cycles in a water bath between 5-55°C (dwell time: 30 seconds in every bath and transfer time: 10 seconds). Then, they were immersed in a 2% basic fuchsin dye solution for 24 hours. After rinsing with water, they were sectioned mesiodistally and evaluated for microleakage using a stereomicroscope.

RESULTS

Independent t-test (Mann-Whitney test) showed no statistically significant difference for microleakage in mesial and distal class II restorations between GC Kalore composite and Luna SDI composite (p = 1.000) (p= 0.852). A total of 83.4% of the Luna SDI composite samples and 66.6% of the GC Kalore composite had a microleakage score of ≤3 in class II cavities.

CONCLUSION

In the present study, marginal microleakage was found mainly at the gingival floor extending to 1/3 of the axial wall for the Luna SDI composite and GC Kalore composite. Furthermore, no statistically significant difference was found between the microleakage of the Class II cavities restored with Luna SDI composite and GC Kalore composite.

Clinical Steps for Restoration of Fractured Anterior Teeth: Color Protocol with Non-VITA Scale

Direct composite resin restorations are commonly provided because of their satisfactory esthetics and minimal wear of opposing tooth structure. Recent restorative systems may not follow the nomenclature of the classical VITA shade guide, using instead a simplified resin color system. A better understanding of these systems and their behavior regarding the incidence of light is an excellent approach to anterior restorations, especially for fractured anterior teeth. This paper demonstrates the color selection and clinical sequence for the natural reproduction of tooth structure using a resin system that does not follow the VITA classical scale.

Effect of Adhesive Restoration and Bleaching Technique on the Concentration of Hydrogen Peroxide In the Pulp Chamber

This study aimed to quantify the concentration of hydrogen peroxide into the pulp chamber in the presence or absence of adhesive enamel restorations and to analyze the resin-dentin interface of bleached groups. Bovine incisors (120) were randomly divided into three groups according to enamel treatment (n=40 each): (1) enamel without restoration (control); (2) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a silorane-based (SB) system; or (3) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a dimethacrylate-based (DB) system. Restorations were thermocycled, and all groups were submitted to one application of 35% hydrogen peroxide (HP) agent for 45 minutes and subjected to four light activation methods (n=10 each): without light, light-emitting diode (LED), LED/diode laser, or halogen light. Acetate buffer solution was placed into the pulp chamber before bleaching, and this solution was collected to spectrophotometrically determine the concentration of HP that reached the pulp chamber after bleaching. Rhodamine B was added to the HP agent and applied on additional enamel samples of each group for 24 hours. Samples were sectioned mesiodistally, and the bleaching agent was traced using confocal microscopy. According to two-way analysis of variance and Tukey test (α=0.05), the HP concentration in the pulp chamber of the control group was significantly lower than that of the SB group (p<0.05), regardless of light activation. No differences were observed between DB and SB groups and between control and DB groups, except for the DB halogen light activated group, which exhibited higher HP intrapulpal concentration (p<0.05). Confocal microscopy exhibited HP diffusion through the interface of the SB and DB restored groups as well as enamel prisms in the control group. The SB restorative system increased the HP diffusion into the pulp chamber, but HP was able to diffuse even in the absence of enamel restorations.