---
title: "Reaction Rate of NaOCl in Contact with Bovine Dentine: Effect of Activation, Exposure Time, Concentration, and pH"
description: Unlocking the Secrets of Sodium Hypochlorite's Efficacy in Endodontic Treatment.
---

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# [Reaction Rate of NaOCl in Contact with Bovine Dentine: Effect of Activation, Exposure Time, Concentration, and pH](https://www.nationaldental.com/fotona-case-studies/reaction-rate-of-naocl-in-contact-with-bovine-dentine-effect-of-activation-exposure-time-concentration-and-ph)

 Written by [National Dental Innovations](https://www.nationaldental.com/fotona-case-studies/author/national-dental-innovations) | Jun 10, 2025 7:12:38 PM

*Unlocking the Secrets of Sodium Hypochlorite's Efficacy in Endodontic Treatment.*

Authors: R.G. Macedo, P.R. Wesselink, F. Zaccheo, D. Fanali, L.W.M. Van Der Sluis  
Journal: International Endodontic Journal (2010)

Objective

To investigate how activation methods (ultrasound vs. laser), sodium hypochlorite (NaOCl) concentration, pH, and exposure time influence the reaction rate (RR) of NaOCl when interacting with dentinal walls.

## Materials and Methods

- Samples
  
  : Standardized root canals in bovine incisors.
- **
  
  Variables tested
  
  **:
  
    - NaOCl concentrations: 2% vs. 10%.
    - pH levels: 5 (acidic) vs. 12 (alkaline).
    - Exposure times: 1 vs. 4 minutes.
- **
  
  Irrigation protocols
  
  **:
  
    - Passive ultrasonic irrigation (PUI).
    - Laser-activated irrigation (LAI).
    - Control (no activation).
- **
  
  Activation cycle
  
  **: 1-minute activation followed by 3-minute rest interval.
- **
  
  Analysis
  
  **: Iodine/thiosulfate titration measured iodine concentration to calculate RR.

Key Results

- **
  
  Significant factors
  
  **:
  
    - Longer exposure (4 min) and higher NaOCl concentration (10%) increased RR.
    - Activation (especially LAI) enhanced RR more than passive irrigation.
- **
  
  Insignificant factor
  
  **: pH had no effect on RR for 2% NaOCl.
- **
  
  Post-activation effect
  
  **: Chlorine consumption rose during the 3-minute rest interval, particularly after LAI activation.

Conclusions

Activation methods (notably laser) strongly modulate NaOCl’s reaction rate, improving its efficacy. Extended exposure and higher concentrations further boost RR, while pH does not influence outcomes for 2% NaOCl. These findings highlight the importance of activation in optimizing irrigant activity during endodontic treatment.

[ACCESS THE FULL ARTICLE HERE](https://pubmed.ncbi.nlm.nih.gov/20812947/)

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