Calcium phosphates as fillers for methacrylate-based sealer

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Endodontics

Background:

• Endodontic sealers are crucial for root canal filling.
• Optimizing sealer properties like bond strength and bioactivity is an ongoing research area.
• Phosphate-based materials are being explored for enhanced endodontic applications.

Purpose of the Study:

• To evaluate experimental endodontic sealers containing hydroxyapatite (HAp), alpha-tricalcium phosphate (α-TCP), or octacalcium phosphate (OCP) particles.
• To assess key properties including mineral deposition, push-out bond strength, radiopacity, degree of conversion, film thickness, flow, calcium ion release, and pH.
• To compare the performance of these experimental sealers against a control group.

Main Methods:

• Fifty human premolars were instrumented and divided into five groups.
• Experimental sealers were formulated using urethane dimethacrylate (UDMA), glycerol-1,3-dimethacrylate (GDMA), ethoxylated bisphenol A glycol dimethacrylate (BISEMA), camphorquinone (CQ), N,N-dihydroxyethyl-para-toluidine (DHEPT), and benzoyl-peroxide.
• 10 wt% of HAp, α-TCP, or OCP was added to the resin formulations for property assessment.

Main Results:

• No significant differences in the degree of conversion were observed between groups.
• The AHplus group exhibited the highest push-out bond strength at 28 days.
• Sealants containing HAp, α-TCP, or OCP showed lower flow values but higher calcium ion release compared to the control.
• Mineral deposition was notably higher for the HAp group at 28 days.

Conclusions:

• Endodontic sealers incorporating phosphate fillers demonstrated comparable bond strength, degree of conversion, and film thickness to commercial sealers like AHplus.
• These phosphate-modified sealers exhibited superior calcium ion release.
• Phosphate fillers significantly improve the overall performance of endodontic sealers after 28 days in simulated body fluid.