Dental Caries: Pathology, Causes, and Acid Attack Mechanism

Dental Pathology & Caries Vocabulary

• Pathology: The study of the effects of disease as seen in the structure and function of the body.
• Pathogen: Any organism capable of causing disease.
• Etiology: The study of the causes of disease, including all factors that may be involved in its development.
• Clinical Data: A collection of information gathered about a patient's disease.
  • Symptom: A subjective experience reported by the patient.
  • Sign: An objective finding observed by a clinician (e.g., blood pressure, swelling).
• Diagnosis: The identification of a disease through scientific evaluation of its physical signs, symptoms, medical history, laboratory tests, and other procedures.
• Prognosis: The predicted outcome of a disease, based on the patient's condition and the typical course of the disease under similar circumstances.

Understanding Dental Caries

According to the World Health Organization (WHO), dental caries is an infectious disease characterized by the destruction of calcified dental tissues. This destruction results from the action of acids produced by microorganisms within dental plaque.

It manifests as darkening and softening of the tooth, which may eventually lead to tooth loss and cavity formation. Tooth decay is one of the most prevalent and widespread diseases globally.

Key Caries Pathogens

The presence of specific pathogens is essential for the development of a carious lesion:

• Streptococcus mutans: A primary bacterium responsible for initiating carious lesions due to its high acid production.
• Streptococcus sanguinis: Important in the colonization of cavities.
• Lactobacillus acidophilus: These bacteria facilitate the progression of carious lesions.
• Actinomyces: Anaerobic bacteria often present in root caries.

The Acidogenic Theory of Caries

Bacteria present in the mouth react with dietary carbohydrates. These bacteria ferment the carbohydrates, producing fatty acids that lower the pH to a critical level, typically between 4.5 and 5.5. This is known as the critical pH.

This low pH occurs within 1 to 3 minutes after carbohydrate ingestion. This acid causes initial demineralization, often appearing as white spot lesions.

After an acid attack, it takes the body approximately 10 to 30 minutes to return to its normal pH level, primarily through the buffering action of saliva.

The first area of enamel to demineralize is the inter-prismatic region, followed by the prismatic enamel. This process releases fluoride and calcium ions, which can remain stagnant in the lesion.

• The dentin has a significant organic component, which facilitates the passage of acid, making dentin more susceptible to injury than enamel.
• When a carious lesion occurs in the cementum, there is no lateral expansion.
• A lesion in dentin is typically larger than in enamel.
• A cemento-dentinal lesion will typically progress uniformly.