Dental Caries Etiology: Theories, Factors, and Microbial Role

Legend of worm

An early theory suggesting that a tooth worm bore a hole through teeth and fed on the blood of teeth and roots of jaws.

Chemical Theory

Proposed by Robertson in 1835, stating that caries was caused by the chemical disintegration of the tooth due to putrefaction of protein leading to ammonia formation, which was oxidized to nitric acid.

Parasitic or Septic Theory

Proposed by Erdl and Ficinus in 1843, suggesting that filamentous microorganisms caused decomposition of the teeth.

Humoral Theory

An endogenous theory stating that an imbalance in the four elemental fluids (humors) of the body—blood, phlegm, black bile, yellow bile—determines a person's physical and mental constitution.

Vital Theory

Proposed by Hippocrates, Celsus, Galen, and Avicenna in the 18th century, postulating that tooth decay originated from within the tooth itself, similar to bone gangrene.

Chemico-Parasitic Theory

Proposed by Miller in 1890, stating that caries is caused by acids produced by oral bacteria following the fermentation of sugar, consisting of two stages: decalcification of enamel and dissolution of softened residue.

Proteolytic Theory (Heider and Bodecker)

Proposed in 1878, stating that the organic portion of the tooth serves as pathways for advancing microorganisms causing demineralization of the teeth.

Proteolytic Theory (Gottlieb)

Proposed in 1944, suggesting that the initial lesion of the carious process is due to proteolytic enzymes attacking the lamellae, rod sheaths, tufts, and walls of tubules.

Proteolytic Theory (Pincus)

Proposed in 1949, stating that the first step in the carious process is the breakdown of dental cuticle, with sulfatase enzyme producing sulfuric acid that destroys the inorganic component of enamel.

Proteolysis-Chelation Theory

Proposed by Schatz in 1955, stating that dental caries is a bacterial destruction of organic components of enamel, with simultaneous microbial degradation and dissolution of inorganic parts by chelation.

Etiologic factors in dental caries

Factors include the host (teeth, saliva), microflora, substrate (diet), and time.

Economic status of population

A factor influencing the economic implications of dental caries treatment.

Increasing educational status

A factor influencing the economic implications of dental caries treatment.

Growing number of dental graduates

A factor influencing the economic implications of dental caries treatment.

Insurance programs

A factor influencing the economic implications of dental caries treatment.

Commercial pressure

A factor influencing the economic implications of dental caries treatment.

Governmental influences

A factor influencing the economic implications of dental caries treatment.

Dental caries

A multifactorial disease characterized by the interplay of host factors, microflora, substrate, and time.

Host factors

Factors related to the teeth and saliva that influence the development of dental caries.

Microflora

The microorganisms present in the mouth that contribute to the development of dental caries.

Substrate

The diet that provides the necessary nutrients for the bacteria that cause dental caries.

Time

A necessary factor for the development of dental caries.

Composition of enamel

Enamel is composed of 96% inorganic material and 4% organic matter plus water.

Composition of dentin

Dentin is composed of 65% inorganic material and 35% organic matter plus water.

Composition of cementum

Cementum is composed of 45-50% inorganic material and 50-55% organic matter plus water.

Morphological characteristics of the tooth

Deep narrow occlusal fissures and buccal and lingual pits predispose to dental caries.

Tooth position

Malaligned or improperly positioned teeth may favor food accumulation and lead to dental caries.

Saliva

A host factor with composition, pH, quantity, viscosity, and antibacterial factors that influence dental caries.

Age

Dental caries decreases as age increases; root caries are common in elders.

Socioeconomic status

High socioeconomic status correlates with a lower chance of dental caries.

Streptococcus mutans

A microorganism associated with early carious lesions of enamel.

Lactobacilli

A microorganism associated with dentinal caries.

Actinomyces

A microorganism associated with root caries.

Dental plaque

A soft, non-mineralized bacterial deposit that forms on inadequately cleaned teeth.

Acquired pellicle

An important component of dental plaque that may facilitate plaque formation.

Diet

An increase in carbohydrates correlates with increased carious activity.

Clearance time of sugar

The time it takes for sugar to be cleared from the tooth surface, which correlates with caries activity.

Caries of enamel

Includes smooth surface caries and pit and fissure caries.

Caries of dentin

Refers to the decay that occurs in the dentin layer of the tooth.

Caries of cementum

Refers to the decay that occurs in the cementum layer of the tooth.