The chart of development of caries

In general tooth decay is caused by specific types of acid-producing bacteria that cause damage in the presence of fermentable carbohydrates such as sucrose, fructose, and glucose.

The mineral content of teeth is sensitive to increases in acidity from the production of lactic acid.

As variant of norm, there is a specific balance between the tooth and surrounding saliva, between demineralization (process of loss of mineral components) and remineralization (process of restructuration of enamel by the receipt of mineral components).

When the pH at the surface of the tooth drops below 5.5, demineralization proceeds faster than remineralization This results in the ensuing decay.

Hard tissues of tooth are under influence of microorganisms of dental deposits, carbohydrates from food, mouth liquid. Carbohydrates are the source of formation of acids, assist formation of dental deposits and developing of cariogenic microorganisms, does not assist self- cleaning. Microorganisms of dental deposits produce acid, supporting considerable time its critical concentration.

State of organs and systems of organism influence on an amount and quality saliva and mouth liquid. Age and ecology have influence on the state of organs and systems of organism.

Ultrastructural enamel defects (the pores) allow the exit of plaque acids direct to the subsurface region. The initial acid attack preferentially dissolves the magnesium and carbonate ions and is later followed by a removal of the less soluble calcium, phosphate, and other ions that are part of the crystal. Eventually the undermined surface zone collapses. Concurrent with this change, the more soluble proteins are lost from the subsurface matrix. Once cavitation occurs, the zones of the incipient lesion become less clearly defined because of mineral loss and the presence of bacteria, bacterial-end products, plaque, and residual substrate, which may support further lesion development.

The role of saliva in process of caries development.

Dental caries can be defined as a carbohydrate-modified transmissible local in- fection with saliva as a critical regulator.

The sources and composition of saliva

The saliva is derived mainly from the major salivary glands the parotid, submandibular, and sublingual glands. Composition and quality of secrets of different glands differ from each other.

The parotid produces a serous (watery, mucous-poor) fluid containing eletrolytes, but is relatively low in organic substances. The parotid gland secretes the majority of the sodium bicarbonate that is essential in neutralizing acids produced by cariogenic bacteria in the dental plaque, and the majority of the enzyme amylase that initiates intraoral digestion of carbohydrates.

The submandibular gland secretes a mixed serous and mucuos fluid, while the sublingual gland has a greater proportion of mucous output than the other major glands.

The minor glands palatal, lingual, buccal, and labial salivary glands empty onto the mucus membrane in many locations on the palate, under the tongue, and on the inner side of the cheeks and lips. These minor glands are mainly mucous secreting glands that lubricate these surfaces and allows for improved mastication and passage of food substance into the esophagus. The minor salivary glands also contribute fluoride that bathes the teeth and enhances caries resistance.

Pure saliva produced by the oral glands is sterile, until it is discharged into the mouth. The mixed saliva is mixture of pure saliva from all sources.

When the fluids from all major and minor glands mix with each other, this secretion becomes known as whole saliva. Whole saliva is further altered by the presence of particles of food, tissue fluid, lysed bacteria, and sloughed epithelial cells. It becomes even more complex with the inclusions of living cells and their metabolic products, for example, bacteria and leucocytes, the latter derived from the gingival crevices and tonsils.

Daily from 300 to 1500 ml of saliva is determined in the oral cavity. The productions of saliva during twenty-four hours is different : (the flow rate is 0,25-0,50 ml/of mines), ), and in nightly sleep salivation stops ceases (0,1 ml/of mines) practically.At every instant there is about 0,5 ml of saliva in the oral cavity.

saliva on a 99,5% consists of water. Mineral and organic components make all 0,5% of its volume

The functions of saliva The physical and chemical protective functions of saliva can be divided into five convenient categories:

lubrication, flushing/rinsing, chemical, antimicrobial (includes antibacterial, antifungal and antiviral), maintenance of supersaturation of calcium and phosphate level batheing the enamel, helping to inhibit demineralization and/or to aid remineralization of tooth structure.