Cerium- and samarium-nitrate interaction and accumulation on human dentin

Area of Science:

• Dental Materials Science
• Microbiology
• Biochemistry

Background:

• Dentin caries and hypersensitivity are significant dental concerns.
• Smear-layer presence affects the interaction of agents with dentin.
• Novel compounds are needed for effective caries prevention and treatment.

Purpose of the Study:

• To evaluate cerium nitrate and samarium nitrate accumulation on dentin.
• To assess the antibacterial activity of these nitrates.
• To determine the influence of the smear-layer on their efficacy.

Main Methods:

• Dentin-enamel slices were prepared with and without smear-layer.
• Specimens were treated with cerium nitrate or samarium nitrate solutions.
• Elemental composition was analyzed using Energy-Dispersive X-ray spectroscopy (EDX).
• Antibacterial activity against oral bacteria was determined by colony-forming unit counts.

Main Results:

• Both cerium and samarium nitrates accumulated on dentin, with varying amounts depending on the smear-layer.
• Application of these nitrates significantly reduced calcium/phosphorus ratios in dentin.
• High calcium/nitrogen ratios were observed with the smear-layer present.
• Significant reduction (≥ 5 log10 steps) in Streptococcus mutans, Actinomyces naeslundii, and Schaalia odontolytica was achieved.

Conclusions:

• Cerium and samarium nitrates demonstrate accumulation on dentin.
• These compounds possess notable antibacterial activity against key oral pathogens.
• Potential applications include the prevention and treatment of dentin caries and root caries.
• They may also be beneficial for managing dentin hypersensitivity.