Microbiology of Dental Caries: Unit 21

Classification of Dental Caries

• Dental caries can be classified based on the location of the lesion as pit and fissure caries, smooth surface caries, and root caries.

Theories of Dental Caries

• The theory of dental caries that dates back to the VII century BC suggests that cavities are due to the acids produced by microorganisms from sugars.
• The Chelation theory proposes that bacterial proteolytic enzymes degrade organic matter, releasing chelating agents that dissolve tooth minerals.

Prevalence of Dental Caries

• In Spain, approximately 80% of the population is affected by dental caries.

Consequences of Dental Caries

• Consequences of dental caries include tooth tissue destruction, pain, and potentially, systemic infections.

Types of Caries

• Recurrent caries is associated with an existing restoration.
• Rampant caries is a type of decay that is described as the most frequent in the initial lesion of caries affecting the enamel.
• Secondary caries occurs in the dentin.

Tooth Tissue Destruction

• The main cause of tooth tissue destruction in dental caries is the acid produced by microorganisms from sugars.

Keyes Scheme

• The Keyes Scheme involves three factors in dental caries: tooth, oral microbiota, and diet.

Bacteria and Dental Caries

• Streptococcus mutans is known for producing insoluble extracellular polysaccharides from sucrose, helping them adhere to tooth surfaces and bind more bacteria.
• Lactobacilli become predominant when pH drops below a certain range.
• Actinomyces bacteria predominate in tissues such as root and dentine.
• Streptococcus sanguis is isolated from the oral cavity of people without caries.

Factors Contributing to Dental Caries

• Factors that can contribute to breaking the balance between demineralization and remineralization, leading to the appearance of caries, include diet, oral microbiota, and tooth characteristics.
• A diet high in sugars and acids can favor aciduric bacteria, such as S.mutans and lactobacilli, becoming predominant.

pH and Demineralization

• The pH range below which demineralization of enamel starts is 5.5.

Prevention of Dental Caries

• Fluoride utilizes the mechanism of inhibition of acid production and inhibition of enzymatic activity to prevent dental caries.
• Noncaloric sweeteners, such as xylitol, can prevent dental caries by reducing the amount of sugars available for fermentation by bacteria.
• The primary effect of polyols, such as xylitol, in preventing dental caries is to reduce the production of acid by bacteria.
• Systemic fluoride intake is primarily from community water fluoridation.

Control of Dental Caries

• The primary method for controlling bacterial plaque is good oral hygiene practices, including regular brushing and flossing.
• Patients at high risk of dental caries can be identified through a combination of clinical examination, radiographs, and evaluation of diet and oral hygiene habits.
• The main purpose of identifying patients at high risk of caries is to provide targeted prevention and early intervention.

Bacteriocins

• Bacteriocins can inhibit the growth of Streptococcus mutans.

Excessive Fluoride Intake

• A potential consequence of excessive fluoride intake is dental fluorosis, which can cause white spots on the teeth.

Explore the microbiology of dental caries in this quiz covering the definition, impact, and relevance of this chronic infectious disease. Learn about the bacteria in dental plaque and the effects on tooth tissues, including enamel, dentin, and cement.