Zeynep Aydin

This in vitro study evaluated the effect of exposure duration (5, 20, and 40 days) to constant increased ambient pressure (2.4 atmospheres absolute; ATA) on microleakage at the dentin–composite interface of teeth restored with two bulk-fill composites. Specimens stored in distilled water at atmospheric pressure (1 atm) served as controls. A total of 192 extracted human molars with standardized Class V cavities were randomly assigned to two groups: sonic-activated bulk-fill composite (SonicFill) or conventional bulk-fill composite (Filtek One Bulk Fill). Each group was subdivided into controls maintained under atmospheric pressure (1 atm) and specimens under hyperbaric pressure (2.4 ATA), and exposed for 5, 20, or 40 days (total of 12 groups, n = 16 per group). Microleakage was assessed using the dye penetration method and scored under a stereomicroscope according to ISO criteria. Statistical analyses were performed using Fisher’s Exact chi-squared and Fisher–Freeman–Halton Exact tests (α = 0.05). No significant differences were found between materials or pressure conditions at 5 and 20 days (p > 0.05). After 40 days, both composites showed significantly higher microleakage at increased pressure than atmospheric controls (p < 0.05). Microleakage increased over time in the hyperbaric groups, while no time-dependent changes occurred at atmospheric pressure. After 40 days, prolonged exposure to elevated pressure increased microleakage, whereas shorter exposure produced no significant changes. Both materials demonstrated similar susceptibility to pressure-related deterioration.

This study evaluated the effects of different provisional luting cement removal methods on the shear bond strength (SBS) of resin cement to dentin following immediate dentin sealing (IDS) performed with two adhesive systems. A total of 168 extracted, caries-free human third molars were used, of which 144 were allocated for SBS testing and 24 for scanning electron microscopy (SEM) analysis. Specimens were assigned according to the IDS protocol (no IDS, IDS with OptiBond FL, or IDS with G2-Bond), followed by provisional cementation using an eugenol-free temporary cement. Contaminated surfaces were subsequently cleaned with a hand scaler, aluminum oxide (Al₂O₃) air abrasion, or Katana Cleaner prior to final bonding with a dual-cure resin cement. SBS was measured after 24 h of water storage, and surface morphology was evaluated by SEM at 2500× magnification. IDS significantly increased SBS under uncontaminated conditions, with G2-Bond-based IDS exhibiting higher bond strength values than specimens without IDS. However, provisional cement contamination significantly reduced SBS regardless of the cleaning method applied, and none of the tested protocols fully restored the bond strength observed in uncontaminated IDS-treated dentin. SEM analysis revealed residual cement remnants and surface alterations after cleaning, even in specimens that appeared macroscopically clean. Within the limitations of this in vitro study, IDS enhances resin–dentin bonding when contamination is avoided; however, current mechanical and chemical cleaning methods are insufficient to completely recover bond strength compromised by provisional cement contamination, highlighting the importance of preventing contamination and preserving IDS layer integrity during indirect restorative procedures.