IADR Abstract Archives

Predominant failure underneath hybrid-layer with mild self-etch adhesives after aging

Objectives: The objective of this study was to investigate the degradation mechanisms with self-etch adhesives (SEAs). SEAs have been associated with several problems, such as hydrophilicity and water-uptake of the adhesive resin, suboptimal polymerization, permeability, nanoleakage and droplets in the adhesive layer. Their degradation mechanisms are still largely unknown, but it is conceivable that these problems may weaken the adhesive layer and adversely influence the longevity of the bond. It was hypothesized that a weakened adhesive layer jeopardizes long-term bonding with SEAs.

Materials&Methods: Five mild SEAs were included: Clearfil S3Bond (Kuraray), G-Bond (GC), iBond (iB), Clearfil SE Bond (Kuraray) and Clearfil Protect Bond (Kuraray). Optibond FL (Kerr), a 3-step etch&rinse adhesive, was included as control. Their micro-tensile bond strength (µTBS) was tested after 24h or 6m water-storage. Their interfaces to enamel and dentin were characterized by electron microscopy after 24h or 6m. Failure analysis was done by TEM of interface cross-sections.

Results: While the bond strength to enamel remained stable after 6m for all adhesives, the bond strength to dentin decreased severely for the SEAs. TEM revealed that dentin-samples of SEAs suffered from filler wash-out, which may indicate unstable, hydrolysis-sensitive filler-matrix coupling due to water absorption from the dentin. TEM of fractured µTBS samples revealed that the bond of dentin-samples failed predominantly underneath the hybrid layer. Possible reasons may be insufficient smear-layer removal and consequently incomplete resin-infiltration, and/or perhaps unstable calcium-phosphate deposition and embedding.

Conclusion: Regarding durability, the etch&rinse adhesive Optibond FL outperformed the mild self-etch adhesives. In spite of the presence of droplets and nanoleakage in the adhesive layer of the SEAs, the weakest area of the interface appeared to be located directly underneath the hybrid layer.


Continental European, Israeli, Scandinavian Divisions Meeting
2009 Continental European, Israeli, Scandinavian Divisions Meeting (Munich, Germany)
Munich Germany
2009
31
Scientific Groups
  • Van Landuyt, Kirsten L.  ( Leuven BIOMAT Research Cluster, Catholic University of Leuven, Leuven, N/A, Belgium )
  • De Munck, Jan  ( Leuven BIOMAT Research Cluster, Catholic University of Leuven, Leuven, N/A, Belgium )
  • Mine, Atsushi  ( Leuven BIOMAT Research Cluster, Catholic University of Leuven, Leuven, N/A, Belgium )
  • Peumans, Marleen  ( Leuven BIOMAT Research Cluster, Catholic University of Leuven, Leuven, N/A, Belgium )
  • Lambrechts, Paul  ( Leuven BIOMAT Research Cluster, Catholic University of Leuven, Leuven, N/A, Belgium )
  • Van Meerbeek, Bart  ( Catholic University of Leuven, Department of Conservative Dentistry, Leuven, N/A, Belgium )
    • Oral Session
    Dental Materials 4
    09/10/2009