Understanding Dental Caries: Types, Causes, and Progression

Root Caries

Root caries refers to decay affecting the root surfaces, specifically involving tissues such as cementum and dentin.

Types of Fillings (Black's Classification)

• Type I: Affects the occlusal surface in premolars and molars.
• Type II: Affects the proximal surfaces of incisors and canines.
• Type III: Affects the proximal surfaces of anterior teeth without involving the incisal edge.
• Type IV: Affects the proximal surfaces of incisors and canines with involvement of the incisal edge.
• Type V: Affects the cervical third of the facial or lingual surfaces of any tooth.

Acquired Pellicle

The acquired pellicle is a thin organic layer formed by salivary glycoproteins that coats the tooth surface within seconds of exposure to saliva. While it can be removed by brushing, it reforms immediately upon contact with saliva.

Functions of the Pellicle

• Protection: Shields the tooth surface against excessive wear from chewing.
• Acid Resistance: Protects against acid attacks by reducing the impact of acidic foods.
• Ion Storage: Acts as a reservoir for protective ions such as fluoride.

Characteristics of Enamel Caries

Enamel caries typically present as an opaque white patch. These are often reversible lesions that can remineralize, sometimes resulting in a darker, more resistant surface. We can distinguish four zones:

• 1. Surface Zone: Unaffected tissue undergoing constant remineralization due to saliva contact.
• 2. Body Zone: Characterized by a larger size and a greater number of pores.
• 3. Dark Zone: The enamel has lost its crystalline structure, showing increased porosity and pigmentation.
• 4. Translucent Zone: Corresponds to the advancing front of the injury.

Dentin-Pulp Response

When subjected to weak, prolonged stimulation, the tooth produces sclerosis of the dentinal tubules. These tubules become filled with peritubular dentin. Radiographically, this appears as a more radio-opaque zone, while clinically, it presents as a darker, harder area that acts as a barrier to prevent irritants from reaching the pulp.

Rampant Caries

Rampant caries is an acute, rapidly evolving form of decay. While the exact cause is multifactorial, it is heavily influenced by poor dietary habits and inadequate oral hygiene. It often affects teeth not typically prone to decay and presents as soft, yellowish-brown lesions. It is most frequently found in two age groups: 4 to 8 years (primary dentition) and 11 to 13 years (permanent dentition).

Radiation Caries

Radiation caries are widespread and develop very rapidly in patients undergoing head and neck radiation therapy. These cavities typically occur at the cervical margins and are caused by radiation-induced changes in oral flora and a reduction in both the quantity and quality of saliva.