Dental Caries: Classification & Chronology

Classification of Dental Caries

• Dental caries can be classified based on 17 factors.
• These classifications help in understanding the nature, progression, and management of dental caries.
• The 17 classifications are: Chronology, Tissue affected, Anatomical site, surfaces to be restored, number of tooth surfaces involved, whether it is a new lesion or recurrent, whether caries is completely removed or not, activity of carious lesion, speed of caries progression, pathway of caries spread, severity, Black's classification, visual classification, WHO system classification, radiographic classification, Mount & Hume classification, and ICDAS classification.

Chronology

• This classification categorizes caries based on the age group.
• Early Childhood Caries occur in ages 4-8.
• Adolescent Caries occur in ages 11-19.
• Adult Caries occur in ages 55-65.

Early Childhood Caries (Ages 4-8)

• This includes nursing caries and rampant caries.
• Nursing caries are typically seen in infants and toddlers, affecting the primary dentition, but usually not the mandibular incisors. Common Etiology is improper bottle feeding and pacifiers dipped in sweeteners.
• Rampant caries can be seen in all ages, including adolescence and affects the primary and permanent dentition, including the mandibular incisors. Etiology is multifactorial involving frequent snacks, sticky refined carbohydrates, decreased salivary flow, and genetic background.

Adolescent Caries (Ages 11-19)

• This is a variant of rampant caries.
• It involves teeth generally considered immune to decay.
• Caries are rapidly burrowing with a small enamel opening.
• A large pulp chamber is often present, leading to early pulp involvement.

Adult Caries (Ages 55-65)

• Recession of the gingiva and decreased salivary function due to atrophy may occur.
• This is the third peak of caries observation.
• Root and cervical caries are commonly found.
• Association noted with partial denture clasps.

Tissue Affected

• Caries are classified based on the tissue that has been affected.
• These are Enamel, Dentin, and Cementum. Early enamel caries appear as "white-spot lesions"

Anatomical Site

• Caries are also classified based on where they occur in the mouth.
• These are Pits and fissures, smooth surfaces, and root caries.

Surfaces to Be Restored

• O indicates occusal surfaces.
• M indicates mesial surfaces.
• D indicates distal surfaces.
• F indicates facial surfaces.
• B indicates buccal surfaces.
• L indicates lingual surfaces.
• MOD indicates mesio-occluso-distal surfaces.

Number of Surfaces Involved

• Simple caries involve only one tooth surface.
• Compound caries involve two surfaces of a tooth.
• Complex caries involve more than two surfaces of a tooth.

New Lesion or Recurrent Caries

• Initial or primary caries are on unrestored surfaces and can be incipient or cavitated.
• Recurrent or secondary caries occur adjacent to existing fillings.

Caries Removal

• Partial caries removal involves indirect pulp capping.
• Complete caries removal is also a treatment option.

Activity of Carious Lesion

• Active lesions are progressive.
• Inactive or arrested lesions may have formed earlier and then stopped progressing.

Speed of Caries Progression

• Acute caries progresses rapidly with soft dentin, large flakes, and a light color. They are often painful, involve several teeth, and are associated with bad oral hygiene and the deepest layers of the tooth affected by acids.
• Chronic caries progresses slowly with hard, dark-colored lesions that are difficult to excavate.

Pathway of Caries Spread

• Forward caries: Decay starts in enamel and involves the dentin. The caries cone in enamel is larger than or at least the size of that in dentin (pit decay).
• Backward caries: The carious process progresses faster in dentin than in enamel, leading to lateral spread and undermined enamel. Decay attacks enamel from its dentinal side. Caries in dentin-enamel junction (DEJ) exceed the adjacent caries in enamel

Caries Severity

• Severity ranges from Incipient to Severe, as caries progresses through enamel into dentin.

Black's Classification

• Class 6 (Simon’s modification) is a classification of lesions involving cuspal tips and incisal edges of teeth.

Visual Classification (Occlusal Surfaces)

• 0 means there are no or slight changes in enamel translucency after prolonged air drying.
• 1 means opacity is hardly visible on the wet surface but distinctly visible after air drying.
• 2 means opacity (white or yellow) is distinctly visible without air drying.
• 3 means there is localized enamel breakdown in opaque or discolored enamel and/or grayish discoloration from underlying enamel.
• 4 means there is cavitation in opaque or discolored enamel exposing the dentin beneath.

WHO System (Shape and Depth)

• The shape and depth of the caries lesion are scored on a four-point scale.
• D1 means there are clinically detectable enamel lesions with intact (non-cavitated) surfaces.
• D2 means there are clinically detectable cavities limited to enamel.
• D3 means there are clinically detectable cavities in dentin.
• D4 means lesions extend into the pulp.

Radiographic Caries Classification

• E1 means the caries is in the outer half of the enamel.
• E2 means the caries is in the inner half of the enamel.
• D1 means the caries is in the outer third of the dentin.
• D2 means the caries is in the middle third of the dentin.
• D3 means the caries is in the inner third of the dentin.

Mount & Hume Classification

• An initial lesion at any site can be identified but has not yet resulted in surface cavitation. It can possibly be healed. (Size 0)
• A Smallest minimal lesion requires operative intervention. The cavity is into dentin just beyond healing through remineralization. (Size 1)
• A Moderate-size cavity. There is still sufficient sound tooth structure to maintain the integrity of the remaining crown. (Size 2)
• There is already a split at the base of the cusp, or if not protected, a split will likely develop. (Size 3)
• The cavity is extensive, following the loss of cusp from a posterior tooth or an incisal edge from an anterior tooth.(Size 4)

International Caries Detection and Assessment System (ICDAS)

• ICDAS classifies caries on a scale from 0 to 6.
• 0 means a sound tooth surface, no or slight change after prolonged air drying.
• 1 means the first visual change in enamel is seen after prolonged air drying.
• 2 means there are distinct visual changes in enamel.
• 3 means there is localized enamel breakdown but no dentin involvement.
• 4 means there is an underlying dark shadow from dentin (not cavitated into dentin).
• 5 means there is a distinct cavity with visible dentin.
• 6 means there is an extensive distinct cavity with visible dentin.