21.3 Caries Diagnosis, ICDAS and Risk Assessment

Caries Diagnostic Systems: ICDAS & Radiographic Correlation

The International Caries Detection and Assessment System (ICDAS) provides an evidence-based visual-tactile system for categorizing caries from early non-cavitated stages to extensive cavitation:

  ICDAS Staging Severity
  Code 0: Sound Tooth Surface (no visual change after 5s air dry)
    │
  Code 1: First Visual Change in Enamel (seen ONLY AFTER 5s air dry, or inside pit/fissure)
    │
  Code 2: Distinct Visual Change in Enamel (visible WET and dry, wider than fissure)
    │
  Code 3: Localised Enamel Breakdown (microcavitation, NO visible dentine)
    │
  Code 4: Underlying Dark Shadow from Dentine (with or without enamel microcavitation)
    │
  Code 5: Distinct Cavity with Visible Dentine (involving <50% of the tooth surface)
    │
  Code 6: Extensive Distinct Cavity with Visible Dentine (involving ≥50% of the tooth surface)

Caries Risk Assessment in UK Practice: Delivering Better Oral Health (DBOH)

In UK NHS and private practice, caries risk assessment (CRA) dictates recall intervals (under NICE guidelines: 3 to 12 months for children; 3 to 24 months for adults) and targeted preventive interventions based on the UK Department of Health & Social Care toolkit, Delivering Better Oral Health: an evidence-based toolkit for prevention (4th Edition, updated 2021/2026).

Caries Risk Stratification Factors

• High Risk: Presence of one or more active carious lesions in the past 12–24 months; multiple restorations; frequent daily intake of fermentable sugars between meals (>3 times daily); xerostomia (salivary flow rate <0.1 mL/min unstimulated or <0.5–0.7 mL/min stimulated due to Sjögren's syndrome, head and neck radiotherapy, or polypharmacy); orthodontic fixed appliances; low socioeconomic status; inadequate fluoride exposure; high plaque scores (>20%).
• Medium / Moderate Risk: No new active carious lesions, but irregular attendance, restored teeth, borderline oral hygiene, or dietary vulnerabilities.
• Low Risk: Zero active carious lesions; regular dental attendance; well-maintained oral hygiene; low-frequency sugar intake confined strictly to meal times; exposed to fluoridated water or daily standard fluoride toothpaste.

Evidence-Based Preventive Regimens (DBOH 4th Edition)

                                  DBOH Preventive Fluoride Ladder
                                                 │
      ┌──────────────────┬───────────────────────┴───────────────────────┬──────────────────┐
      ▼                  ▼                                               ▼                  ▼
Standard Toothpaste   High-Fluoride (2800 ppm)                Ultra-High (5000 ppm)    Fluoride Varnish
• 1350–1500 ppm fluoride   • Prescription-only (POM)               • Prescription-only (POM)• 2.26% NaF
• All patients ≥7 yrs • Age ≥10 years                         • Age ≥16 years            (22,600 ppm)
• "Spit, don't rinse" • High caries risk / active lesions     • Active root caries     • 2x/yr: ages 3–16
• Twice daily         • Orthodontic appliances                • Severe dry mouth       • 3–4x/yr: high risk

1. Fluoride Toothpaste Regimens:

   • Standard Over-the-Counter Toothpaste (1350 to 1500 ppm fluoride):
     • Universal baseline recommendation for all adults and children aged 7 years and older.
     • For children aged 0–3 years: smear of at least 1000 ppm fluoride toothpaste.
     • For children aged 3–6 years: pea-sized amount of 1000–1450 ppm fluoride toothpaste.
     • Crucial public health instruction: "Spit, don't rinse" after brushing. Rinsing with water washes away the residual salivary fluoride reservoir, dramatically reducing remineralisation efficacy.
   • High-Fluoride Toothpaste (2800 ppm fluoride (0.619% sodium fluoride) - POM):
     • Licensing & Indications: Licensed as a Prescription-Only Medicine (POM) for patients aged 10 years and older who are assessed as high caries risk (active caries within the last year, high sugar frequency, or active orthodontic brackets).
     • Use twice daily in place of standard toothpaste.
   • Ultra-High-Fluoride Toothpaste (5000 ppm fluoride (1.1% sodium fluoride) - POM):
     • Licensing & Indications: Licensed as a Prescription-Only Medicine (POM) for patients aged 16 years and older who are at very high caries risk, specifically those with active coronal or root caries, severe dry mouth (hyposalivation), or following therapeutic head and neck radiotherapy.
     • Yields an approximate 28% to 40% caries reduction over standard 1100–1450 ppm toothpastes.

2. Professional Fluoride Varnish Application:

   • Formulation: 22,600 ppm fluoride (2.26% NaF) in an alcoholic colophony resin base (e.g. Duraphat).
   • Mechanism: Adheres to enamel and dentine surfaces in the presence of saliva, precipitating a reservoir of calcium fluoride ($CaF_2$) globules on the tooth surface that slowly release fluoride during subsequent acid attacks.
   • DBOH Application Protocol & Frequencies:
     • Universal Baseline: Applied 2 times per year to all children aged 3 to 16 years.
     • Targeted High-Risk: Applied 3 to 4 times per year for individuals of any age (children and adults) presenting with high caries risk, active lesions, or medical vulnerabilities.
   • Application Technique: Teeth are gently dried with cotton rolls/gauze (no prophylaxis needed). A thin layer is applied with a microbrush directly to pits, fissures, interproximal sites, and cervical margins. Instruct patient to avoid eating, drinking, or hot liquids for 30 minutes, eat soft foods for the remainder of the day, and refrain from brushing until the following morning.

3. Pit and Fissure Sealants:

   • Indications: Recommended for high-caries-risk children and adolescents on the occlusal surfaces of all permanent molars as soon after eruption as isolation permits (typically first molars at ages 6–7; second molars at ages 12–13).
   • Resin-Based Sealants: The gold-standard material of choice. Requires absolute moisture control (rubber dam or skilled cotton roll isolation with high-volume suction) and acid etching with 37% phosphoric acid. Yields high retention and over 70% caries reduction over 2–4 years.
   • Glass Ionomer Cement (GIC) Sealants: Moisture-tolerant provisional alternative. Indicated in partially erupted permanent molars where opercula or patient cooperation prevents moisture isolation for resin bonding. Acts as an interim fluoride-releasing barrier until full eruption allows definitive resin sealants.

Risk status is not a permanent label. It is reassessed at every oral health review, because the factors that drive it — diet, medication, salivary flow, plaque control, social circumstances and the appearance of new lesions — all change. A patient whose risk has fallen may move to a longer recall interval and a less intensive preventive regimen; a patient who develops new lesions, starts a xerostomic medication or experiences a change in circumstances moves the other way. Recording the risk assessment, the factors behind it and the resulting plan at each review is what makes the recall interval defensible.