Effects of calcium phosphate solutions on dentin permeability

Area of Science:

• Biomaterials Science
• Dental Materials Science
• Mineralization

Background:

• Dentinal tubules are microscopic channels within dentin.
• Obstructing these tubules is crucial for reducing dentin hypersensitivity and improving sealing properties.
• Calcium phosphate compounds are known for their potential in biomimetic applications.

Purpose of the Study:

• To investigate the efficacy of calcium phosphate solutions in obstructing dentinal tubules.
• To evaluate the impact of different pH levels and application methods on tubule occlusion.
• To assess the reduction in dentin permeability using these solutions.

Main Methods:

• Human dentin discs (with smear layer, sonicated, or acid-etched) were treated with calcium phosphate solutions.
• Permeability was measured before and after treatment.
• Scanning electron microscopy (SEM) was used for structural evaluation.
• X-ray powder diffraction (XRD) identified precipitated products.
• pH changes monitored precipitation kinetics.

Main Results:

• High concentration calcium phosphate solutions (pH 9.5) rapidly formed amorphous calcium phosphates, obstructing tubules and reducing permeability by ≥85%.
• At pH 5.6, dicalcium phosphate dihydrate crystals formed, with variable tubule occlusion effectiveness.
• Application method influenced the degree of tubule obstruction, particularly at lower pH.

Conclusions:

• Calcium phosphate solutions, especially at high concentrations and pH 9.5, are effective in occluding dentinal tubules.
• Amorphous calcium phosphate precipitation offers a highly effective method for reducing dentin permeability.
• The effectiveness of calcium phosphate precipitation for dentinal tubule obstruction is dependent on solution chemistry and application technique.