Calcium Silicate Particles: Biological and Mechanical Role in the Hybrid Layer

Area of Science:

• Biomaterials Science
• Dental Materials
• Adhesive Dentistry

Background:

• Improving the longevity of bonded interfaces in dental restorations is crucial.
• Ion-releasing particles are explored to enhance adhesive durability.
• Calcium silicate particles (CaSi) show potential for remineralization and bioactivity.

Purpose of the Study:

• To evaluate the effect of calcium silicate particles (CaSi) as a pretreatment and/or additive in a bonding resin on the longevity of bonded interfaces.
• To assess the impact of CaSi on mechanical properties, mineral precipitation, and enzymatic activity at the bonded interface.

Main Methods:

• Calcium silicate particles (CaSi) were applied as a pretreatment to acid-etched dentin and/or added to a commercial 3-step adhesive system.
• Mechanical properties were measured by nanoindentation.
• Mineral precipitation, calcium and phosphorus content, enzymatic activity, and microtensile bond strength were assessed after storage in simulated body fluid (SBF).

Main Results:

• CaSi incorporation reduced the initial mechanical properties of the adhesive layer.
• Significant increases in hybrid layer and dentin mechanical properties were observed with CaSi after prolonged storage, indicating apatite precipitation.
• CaSi inhibited metalloprotease activity and reduced hydroxyproline release.
• Microtensile bond strength decreased in all groups after 12-month storage in SBF.

Conclusions:

• Calcium silicate particles (CaSi), whether as a pretreatment or incorporated into the bonding resin, promote mineral precipitation and inhibit enzymatic activity at the bonded interface.
• CaSi enhances the durability of the hybrid layer and underlying dentin over time.
• While CaSi shows promise for improving bonded interface longevity, further research is needed to optimize bond strength retention.