It is a thin, dense membrane composed of bacteria, bacterial products, and components from the host. It is a microbial environment for bacterial growth.

Dental plaque is the most important factor in the development of dental caries

① It has strong adhesion to the tooth surface, easily forms plaque, and plays a role in plaque;

②Acidogenic and acid-resistant;

③Has the ability to synthesize intracellular polysaccharides and extracellular polysaccharides

acquired membrane-forming salivary proteins

Bacterial adhesion and aggregation

Plaque biofilm maturation

Film adsorption → bacterial aggregation → plaque formation → demineralization formation

Sugar + acidogenic bacteria → organic acid → demineralization

Plaque-tooth interface (basal layer): acquired film

Middle layer: dense layer (cocci); plaque body (clump-like, palisade-like)

Plaque surface (wheat ear-like)

1． Streptococcus

2. Lactobacillus

3. Actinomyces viscosus promotes the colonization of Streptococcus mutans on the root surface, and may have an important synergistic effect on the formation of root surface plaque and the occurrence of root surface caries.

1． The relationship between sugar consumption and the incidence of dental caries: positive correlation

2. Types of sugar: Sucrose has the strongest ability to cause smooth surface caries, and Streptococcus mutans has the strongest ability to metabolize sucrose.

3. The order of cariogenic bacteria: sucrose>glucose>fructose>maltose>lactose>starch>sorbose>xylitol

4. Eating frequency: positive correlation

5. Physical properties and intake methods of sugary foods Fine, sticky foods are highly cariogenic

1． Systemic effects

2. local effect

3. Phosphate

1． Tooth shape: The fissures and fissures of posterior teeth are places where microorganisms and food residues tend to stay, and are prone to caries.

2. Teeth composition

3. Dentition shape constant: lower 6> upper 6> upper and lower 7> upper and lower 5> upper 1> upper and lower 4> lower 1> upper and lower 3

4. Physical and chemical properties of teeth, degree of calcification, trace element content and other factors

Changes in saliva secretion, composition, buffering capacity and antibacterial system are closely related to the occurrence of caries.

Insufficient systemic nutrition in childhood, resulting in deficiencies of calcium, phosphorus, vitamins, and protein and metabolic disorders, can seriously affect tooth development and mineralization, thereby increasing susceptibility to dental caries and significantly worsening the incidence of dental caries.

Caries lesions in the enamel or root surface cementum layer, caries plaque, early caries

The front edge of the caries lesion is located in the superficial layer of dentin, and the dentin is superficially caries.

Progression of lesions into deeper layers of dentin

1． More common in children or young adults

2. The disease progresses quickly, and the diseased tissue is lighter in color, brown-black, and soft and moist in texture. It is also called wet caries.

3. The pulp tissue does not have time to produce repairing dentin, and pulp lesions are prone to occur.

When caries develops to a certain stage, due to changes in the lesion environment, the hidden parts become open, the original pathogenic conditions change, the caries no longer progresses, and the damage remains intact.

Early caries occurs on the proximal surface after tooth extraction; the edge of the molar (occlusal) cavity has no enamel fracture and opening.

Color: yellowish brown; shape: shallow dish; texture: smooth and hard

There are multiple teeth and multiple tooth surfaces in the mouth at the same time in a short period of time, especially the mandibular front teeth that generally do not suffer from caries. If caries occurs, the mouth will become dry after radiotherapy.

Definition: Occurs in treated teeth, around or within old restorations

a. Due to the rupture of the tooth group around the filling edge or cavity, a plaque retention area is formed

b. The restorative material is not close to the tooth tissue, leaving a small gap.

c. It develops later because the diseased tissue was not removed during treatment.