Caries Mechanism Formation and Pathology

Caries Mechanism

Demineralization of enamel initiates caries by organic acid, which is produced by bacteria. Streptococcus mutans, streptococcus mitior, process sanguis are the important organism for the formation of Tooth Caries. Lactobacilli and pseudophillus may have some minor role for acid formation.

Caries Mechanism Formation and Pathology

In the first step of caries mechanism is the formation of plaque on the tooth surface. The stickiness of plaque is caused by dextran which is produced by fermentary dietary food with streptococcus mutans. Then lactic acid is produced and caused demineralization and decalcification of tooth tissue and ultimately caries is formed. If caries mechanism is not prevented, the structure of the tooth will be lost gradually.

Caries Pathology

Enamel Caries Pathology

Enamel is the usual site of the initial lesion unless dentine or cementum becomes exposed by gingival recession. Enamel is the hardest and densest tissue in the body, consists almost entirely of calcium apatite with only a minute organic content. So, it forms a firm barrier to bacterial attack. But, if once enamel has been breached, infection of dentine can be spread easily. Dental caries pathology can be serious for the tooth.

Enamel caries develop in four main phase

The early lesion (Submicroscopic)
The phase of nonbacterial enamel crystal destruction
Cavity formation
Bacterial invasion of enamel
Undermining of enamel from below after spreading into dentine

The early lesion (Submicroscopic) – Submicroscopic changes occur due to the acid formation, Appearance of white opaque spots just adjacent to contact point, The initial lesion is conical in shape with its apex towards the dentine, Sub-microscopically there are 4 zones- Transparent, Dark zone, Body of the lesion, Surface zone.

Cavity formation - When there is cavity formation, bacteria invade the enamel cavity and lies in the dentino-enamel junction and spread laterally and underlined enamel. Three changes occur- Enamel loses its support from dentine and becomes weak; Enamel is destroyed from beneath; Allows the micro-organism to attack dentine over a wide area.

Dentine Caries Pathology

The initial lesion starts as a result of enamel caries before any cavity formation. Diffusion of acid cause little changes in the organic matrix of dentine. But, when bacteria penetrate the enamel, they spread along the amelodentinal junction to attack the dentine over a wide area. The lesion is conical in shape with its apex towards pulp. Spreading of infection is facilitated by dentinal tubules. It forms a pathway open to bacteria. After demineralization, dentine matrix is progressively destroyed by proteolysis. Though streptococcus plays an important role in enamel caries, in case of dentine caries lactobacilli has got a major role. At this stage pulp and dentine try to protect itself by odontoblastic activity so that dentine and pulp should be considered as one tissue.

Dental Caries Mechanism Formation and Pathology can be prevented or treated in many ways. For details see- Oral Hygiene