Dentin demineralization: effects of dentin depth, pH and different acids

Area of Science:

• Dental materials science
• Biomaterials
• Surface chemistry

Background:

• Dentin demineralization is a critical process in dental caries.
• Understanding the kinetics of acid etching on dentin is crucial for developing effective dental treatments.
• Phosphoric acid and citric acid are commonly used in dental procedures.

Purpose of the Study:

• To investigate the relationship between phosphoric acid concentration and dentin demineralization rates.
• To determine if dentin depth affects acid etching characteristics.
• To compare the etching properties of phosphoric acid with citric acid over a similar pH range.

Main Methods:

• Atomic Force Microscopy (AFM) was used to quantify demineralization in wet dentin samples.
• Dentin disks from human molars were etched with phosphoric acid solutions at varying pH levels (0.95, 2.0, 4.0).
• Etching depths of intertubular and peritubular dentin were measured and compared to results from citric acid etching.

Main Results:

• Peritubular dentin demineralization showed a linear relationship with time initially, while intertubular dentin reached a plateau quickly at pH 2.0 and 4.0.
• No significant differences in etching rates were observed between superficial and deep dentin for either peritubular or intertubular dentin.
• Etching rates increased with decreasing pH for both acids, with citric acid demonstrating higher rates than phosphoric acid.

Conclusions:

• Dentin demineralization rates are not directly proportional to acid concentration and are independent of dentin depth.
• The etching characteristics of phosphoric acid and citric acid differ, with citric acid being more aggressive.
• AFM is a valuable tool for quantifying dynamic changes during dentin etching.