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Updated: Aug 15, 2026
08:12
Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants
Published on: March 29, 2018
[Possible limitations in the caries preventive effect of fluorides?]
1Klinikk for Kjeoveortopedi, Universitetet i Oslo.
Den Norske Tannlaegeforenings Tidende
|April 1, 1991
Summary
Fluoride helps prevent tooth decay by forming fluorapatite, but its effectiveness decreases when plaque fluid pH drops below 4.5. At very low pH, mineral loss from enamel cannot be reversed, potentially explaining fluoride
Area of Science:
- Dental research focusing on cariology and the role of fluoride in preventing tooth decay.
Context:
- The cariostatic (caries-inhibiting) effect of fluoride is pH-dependent.
- Plaque fluid pH influences the saturation of hydroxyapatite and fluorapatite.
- Enamel demineralization occurs when plaque fluid is undersaturated with respect to hydroxyapatite.
Purpose:
- To discuss the influence of varying pH levels in plaque fluid on fluoride's cariostatic effect.
- To explain the mechanisms of enamel demineralization and remineralization in the presence of fluoride at different pHs.
Summary:
- At pH 5.5-4.5, plaque fluid is undersaturated with hydroxyapatite but supersaturated with fluorapatite, leading to enamel dissolution and surface fluorapatite precipitation.
- Below pH 4.5, plaque fluid may become undersaturated with fluorapatite, preventing mineral redeposition and leading to erosion.
- This undersaturation of fluorapatite may explain fluoride's reduced efficacy in certain caries-active patients and fissure caries.
Impact:
- Highlights the critical role of pH in the oral environment for effective fluoride action.
- Provides a potential explanation for treatment failures or reduced fluoride efficacy in specific patient groups or dental locations.
- Informs strategies for managing dental caries, particularly in conditions with persistently low plaque pH.
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