Classification of Dental Caries

Dental caries can be classified in various ways based on their location, origin, activity, progression speed, and the design of restorative treatment. Understanding these classifications aids in accurate diagnosis, appropriate treatment planning, and effective patient education.

1. Based on Anatomical Location

1. Pit and Fissure Caries: Commonly occur on the occlusal surfaces of molars and premolars, as well as the buccal and lingual surfaces of molars and the lingual surface of maxillary incisors.
2. Smooth Surface Caries: Found on the gingival third of buccal and lingual surfaces and proximal surfaces of teeth.
3. Root Caries: Develops on the exposed root surfaces, affecting cementum and dentin, typically due to gingival recession.

2. Based on Lesion Origin

1. Primary Caries: Lesions occurring on previously unrestored tooth surfaces.
2.Recurrent (Secondary) Caries: New lesions that develop adjacent to existing restorations.
3. Residual Caries: Demineralized tissue intentionally or unintentionally left beneath a restoration during cavity preparation.

3. Based on Caries Activity

1. Active Carious Lesion: Progressive, actively demineralizing lesion.
2. Inactive (Arrested) Carious Lesion: A previously active lesion that has halted in progression. These lesions are typically open, self-cleansing, and do not retain food debris.

4. Based on Rate of Progression

1. Acute Caries: Rapidly progressing lesions that quickly approach the dental pulp.
2. Rampant Caries: Multiple active lesions involving both usually affected and unaffected surfaces, often linked to poor oral hygiene, frequent intake of fermentable carbohydrates, or reduced salivary flow.
* Types of Rampant Caries:
A. Early Childhood Caries: Seen in primary teeth of young children.
B. Nursing/Bottle Caries: Affects infants and toddlers, notably maxillary incisors.
C. Radiation-Induced Caries( Xerostomia induced rampant caries): Seen in patients post-radiotherapy due to hyposalivation.
3. Chronic Caries: Slowly progressing lesions, often darker and harder in consistency, indicating a long-standing process.

5. Based on Restorative Classification (Black’s Classification)

I. Class I: Caries in pits and fissures of occlusal surfaces, buccal/lingual surfaces of molars, and lingual surfaces of incisors.
II. Class II: Caries on the proximal surfaces of premolars and molars.
III. Class III: Caries on the proximal surfaces of anterior teeth, excluding the incisal angle.
IV. Class IV: Caries on the proximal surfaces of anterior teeth involving the incisal angle.
V. Class V: Caries on the gingival third of the facial or lingual surfaces of all teeth.
VI. Class VI: Caries on the incisal edges of anterior teeth and cusp tips of posterior teeth, not involving any other surface.

6. Visual Classification of Caries on Occlusal Surfaces

This classification is based on visual changes observed in enamel, especially under air-drying conditions:
Score 0: No or minimal change in enamel translucency, even after air drying.
Score 1: Opacity barely visible when wet, clearly visible after drying.
Score 2: White or yellow opacity visible even without drying.
Score 3: Localized enamel breakdown with underlying discoloration (often grayish).
Score 4: Clear cavitation in discolored enamel with exposed dentin.

7. Based on the Pathway of Caries Spread

A. Forward Caries: The lesion cone in the enamel is equal to or larger than the lesion in the underlying dentin.
B. Backward Caries: The caries spreads more extensively along the dentinoenamel junction (DEJ), with dentinal damage exceeding visible enamel involvement. It often progresses back into the enamel from the DEJ.

8. Based on the Number of Tooth Surfaces Involved

A. Simple Caries: Involves only one surface of a tooth.
B. Compound Caries: Involves two surfaces of a tooth.
C. Complex Caries: Involves more than two surfaces.

9. Based on Severity of the Lesion

This classification describes the depth of carious involvement:
I. Incipient Caries: Limited to the outer half of enamel.
II. Moderate Caries: Extends beyond half the enamel thickness but does not reach the DEJ.
III. Advanced Caries: Reaches the DEJ and extends into dentin but is less than halfway to the pulp.
IV. Severe Caries: Lesion progresses beyond the midpoint of dentin, approaching the pulp cavity.