SEM/TEM Analysis of Self-Adhesive Cements: Pulpal Pressure and IDS

Objectives: The aim of this study was to evaluate the effects of simulated pulpal pressure (SPP) and immediate dentin sealing technique (IDS) on the nanoleakage patterns of resin-dentin interfaces produced by different luting agents.

Method: Two self-adhesive luting agents (RelyX Unicem – UN and Clearfil SA Luting – SA) and 2 conventional luting agents (Rely X ARC – RX and Panavia F - PF) were used in this study. Thirty-two human molars were divided in 4 groups according to luting agents. Each group was sub-divided according to SPP and IDS using Clearfil SE Bond (n=5). After IDS was performed, sealed specimens were stored in water for 7 days before luting procedures, which were performed according to manufacturers’ instructions. Half of the specimens were subjected to 15cm H₂O of hydrostatic pressure for 24h before cementation procedures, and continued for 24h after luting procedures. Afterwards, restored teeth were serially sectioned into 0.9 mm-thick slabs, coated with nail varnish and immersed in ammoniacal AgNO₃ for 24 h. After immersion in a photodeveloping solution for 8 h, specimens were prepared for observation with Scanning and Transmission Electron Microscopes. Representative images were used to analyze silver deposition patterns within interfaces.

Result: SPP increased silver deposition for RX, PF and SA. However, UN presented very small silver deposition with or without SPP. Independently of SPP, the IDS technique prevented silver deposition for most groups.

Conclusion: The immediate dentin sealing technique was able to prevent silver deposition for most groups. When simulated pulpal pressure was applied, the benefits of the IDS technique were even more noticeable.