Changes in pH of irrigating solutions after contact with human root dentin

Area of Science:

• Biomaterials Science
• Dental Materials Science
• Biochemistry

Background:

• Root canal irrigation is crucial for effective endodontic treatment.
• Understanding the chemical behavior of irrigating solutions upon contact with dentin is essential for optimizing disinfection protocols.
• The interaction between irrigants and dentin can alter their properties, potentially affecting clinical outcomes.

Purpose of the Study:

• To investigate the in vitro pH changes of various endodontic irrigating solutions when in contact with human root dentin.
• To compare the pH behavior of solutions used individually versus consecutively.
• To determine the effect of contact time (2.5 and 5 minutes) on irrigant pH.

Main Methods:

• Human mandibular premolars were sectioned, and specimens were divided into six groups.
• Groups were treated with: distilled water, 1% sodium hypochlorite (NaOCl), 1% citric acid (CA), 17% EDTA, 1% CA + 1% NaOCl, or 17% EDTA + 1% NaOCl.
• Initial and final pH measurements were recorded after 2.5 or 5 minutes of contact at 37°C. Statistical analysis included T-tests, ANOVA, and Tukey's test.

Main Results:

• Significant pH variations were observed for all tested solutions after contact with root dentin at both time points.
• Distilled water and 1% NaOCl showed a decrease in pH.
• 1% Citric Acid (CA) and 17% EDTA exhibited an increase in pH.

Conclusions:

• The pH of common endodontic irrigating solutions is significantly modified by interaction with human root dentin in vitro.
• These pH alterations, observed with both single and consecutive irrigant use, highlight the dynamic chemical environment within the root canal.
• Clinical protocols should consider these pH changes when selecting and sequencing irrigating solutions for endodontic treatment.