Tooth Decay (Caries): Bacterial Acid Production Is the Cause

Yes, dental caries is an infectious, biofilm-mediated disease caused by specific bacteria.

The Caries Process (Keyes Triad + Time)

1. Susceptible host: Tooth anatomy (pits/fissures), enamel composition, saliva flow/composition.
2. Cariogenic biofilm: Streptococcus mutans, S. sobrinus, Lactobacillus spp. adhere via glucans (Gtf enzymes).
3. Fermentable substrate: Sucrose > glucose/fructose > starch. Frequency > quantity.
4. Time: Repeated acid challenges overwhelm remineralization.

Mechanism

• Bacteria metabolize sugars → **organic acids (lactic, acetic, formic, propionic)**.
• Plaque pH drops <5.5 (critical pH for hydroxyapatite dissolution).
• Demineralization: Ca²⁺ and PO₄³⁻ diffuse out of enamel.
• Remineralization: Saliva (Ca²⁺, PO₄³⁻, fluoride) drives re-precipitation when pH rises.
• **Net mineral loss → white spot lesion → cavitation → dentin involvement → pulpitis.**

Prevention (Evidence-Based)

• Fluoride: Water (0.7 ppm), toothpaste (1000–1500 ppm), varnish (q6mo). Enhances remineralization, inhibits bacterial enolase.
• Oral hygiene: Brush 2×/day (fluoride paste), floss daily, disrupt biofilm.
• Diet: Limit frequency of fermentable carbs; avoid sticky snacks; water between meals.
• Sealants: Pit-and-fissure sealants on molars (↓ caries 80% in sealed surfaces).
• Regular dental visits: Risk-based recall (6–12 mo); early detection → non-invasive arrest (SDF, resin infiltration).

Treatment by Stage

Stage	Intervention
Initial (white spot)	Fluoride varnish, high-fluoride paste, MI paste, sealant, hygiene
Enamel cavitation	Resin composite restoration
Dentin involvement	Composite/amalgam; pulp protection (liner, indirect pulp cap)
Pulpal involvement	Pulpotomy (primary), root canal (permanent), or extraction

Caries is preventable and arrestable early. The bacteria are necessary but not sufficient—diet and hygiene modulate the disease.