Non-carious lesions of the teeth are a large group of diseases and pathologies. These include all damage to enamel, tooth tissue, and infections of nonbacterial nature.
Classification of non-carious lesions of enamel
1. Lesions that occurred before the eruption of teeth (during the follicular development of hard tissues, occur in 5-14% of the population):
- Hypoplasia - underdevelopment of dental tissues;
- Hyperplasia - excessive formation of tooth tissue structures;
- Fluorosis - the destruction of enamel due to excessive fluoride in the body;
- Hereditary diseases.
2. Lesions that occurred after teething (the total prevalence of such diseases is 50-75%):
- Wedge-shaped defect - the appearance of V-shaped defects in the cervical crown of the tooth;
- Erosion - in addition to enamel, the dentinal layer is destroyed, usually occurs on the upper incisors and canines;
- Pathological abrasion of enamel - intense decline of hard tissues on all or some teeth;
- Mechanical injuries of dental crowns - chips, cracks, fractures;
- Necrosis (necrosis) of the hard tissues of the tooth;
- Enamel pigmentation - tetracycline stains and more.
Hypoplasia
Hypoplasia is characterized by insufficient formation and mineralization of tooth enamel. It occurs due to the weakening of histogenesis under the influence of various severe disorders (common, infectious diseases, metabolic disorders, etc.) in the body during tooth formation. Defects on the tooth are formed before it erupts. They can not occur in an entirely properly formed tooth. Carious spots appear after teething. Hypoplasia affects teeth laid and started simultaneously, for example, incisors and first molars. Caries can affect different teeth regardless of their formation and mineralization time. An important differential feature is the localization of the affected areas. In patients with hypoplasia, the spots are most often located on the convex vestibular surface of the front teeth and tubercles of molars and premolars.
On the other hand, caries is rarely localized on convex, smooth surfaces of teeth. It is more often on contact surfaces, pits, and fissures of molars. Spots in the presence of hypoplasia have a pronounced symmetry - localized on the same surfaces of the teeth on the right and left; even their shape and color can be very similar. The symmetry of the lesion also characterizes caries, but spots may not coincide (i.e., on one half of the jaw, they may occur much earlier); the shape and color of carious lesions may differ. Carious spots, after their occurrence, can change their shape and color and further progress with the formation of a carious defect.
On the other hand, acute initial caries can be stabilized under the influence of remineralizing therapy or spontaneously (in case of improvement of the general condition of the body), and chalk-like spots may disappear. Spots in patients with hypoplasia are stable and do not change their shape and color. A child with a weakened body may develop caries at the site of hypoplasia defects. Hypoplasia most often affects permanent teeth, very rarely - deciduous, while caries of deciduous teeth is quite common.
Spots in patients with hypoplasia are light, whitish, have a shiny surface, dense and painless during probing. Acute initial caries is characterized by white, chalky spots with matte, devoid of natural luster enamel; roughness and little surface flexibility are noted during sounding sensitivity. Dense, painless pigmented spots characterize chronic primary caries during probing; these spots often also do not have the inherent luster of intact enamel. The method of vital tooth coloring, most often methylene blue, is used to diagnose initial caries. Teeth are covered with cotton rollers, cleaned of plaque, and dried. The tooth's surface with the stain is applied 2% aqueous solution of methylene blue, and after a few minutes, rinse with water. Carious spots absorb the dye and turn blue due to the enamel's demineralization and increased permeability. Spots in hypoplasia have a denser surface, so do not stain.
Fluorosis
Fluorosis is a peculiar form of hypoplasia, which occurs due to the influence of excess fluoride ions in the case of their increased concentration in drinking water. Fluoride ions inhibit ameloblasts during the formation and mineralization of teeth. Depending on the concentration of fluoride in drinking water on the surface of the enamel can develop quite different lesions: from white, brown, and even black spots to the appearance of enamel defects and even its aplasia. Differential diagnosis of fluorosis and primary cavity is carried out on the same principles as hypoplasia. Fluoride stains on tooth enamel are stationary, have a dense, shiny surface, are smooth and painless during probing, and do not absorb dye on their surface.
In contrast to carious, fluorescent spots are more mineralized and have greater microhardness and resistance to acids due to the significant deposition of fluoroapatite in them. Therefore, almost no caries occurs with fluorosis, while a combination of hypoplasia and caries is common. Fluorosis is not characterized by an evident lesion of certain groups of teeth; depending on the length of life in the area of endemic fluorosis, it can affect several or all teeth.
In some cases, it is necessary to differentiate carious spots from pigmentation and plaque, which are localized on the surface of the teeth. Dental plaque on the surface of the teeth can be stained under the influence of food pigments, medicines, smoking, and more. Children sometimes find a dense green plaque firmly attached to the enamel surface. It is believed to be caused by the fungus Lichen clienteles, which can produce chlorophyll. Such plaque is more often deposited on the dorsal surfaces of the front teeth, i.e., on surfaces that are exposed to light; on canines, it is deposited much less often. Differential diagnosis of these formations, as a rule, is not difficult. Pigment spots and plaques are usually localized on the front teeth' smooth vestibular or lingual (smoker's plaque) surfaces. Despite the relatively tight attachment to the tooth surface, they can be easily removed with special brushes for professional teeth cleaning.
After removing the pigmented plaque, the intact enamel surface is exposed without any signs of carious demineralization. Differential diagnosis of caries with the presence of cavities in the hard tissues of the teeth is carried out with caries of varying depth, hypoplasia, fluorosis, wedge-shaped defects, pathological abrasion of hard tissues of teeth, enamel erosion, necrosis of hard tissues, chronic pulpitis, and periodontitis. When differentiating carious lesions of different depths, it isn't easy to estimate them by the linear or volumetric size of the carious cavity due to variations in the thickness of the hard tissues of different groups of teeth in other parts of the tooth crown. As a result, the depth of the carious cavity must be estimated not by its linear dimensions (for example, in millimeters) but by its placement in the dentin (mantle or pulp) and concerning the pulp. Thus, while examining the carious cavity, it is necessary to determine precisely how thick the dentin layer separates it from the tooth cavity and the pulp placed in it. This is especially important in the case of differential diagnosis of intermediate and deep caries. The superficial carious lesion differs from the intermediate carious lesion primarily in subjective sensations: the intermediate carious lesion is almost not characterized by pain from chemical stimuli. The cavity in the superficial caries is localized only within the enamel, in the intermediate - and the mantle layer of dentin. In a superficial carious lesion, even in the case of an acute course, there are no expressed overhanging edges of enamel, but at an acute intermediate, they are.
Wedge-shaped defects
Wedge-shaped defects are most often located on the vestibular surface in the cervical region of the teeth, which protrude slightly beyond the dentition (canines, premolars, less often - incisors and molars). Unlike caries, they have the characteristic shape of a wedge formed by two planes of the defect. These surfaces are filled with sclerosed, smooth dentin during probing, without any signs of caries demineralization.
Pathological abrasion of teeth
Pathological abrasion of teeth is not accompanied by softening of hard tissues and pigmentation. The shape of the defects corresponds to the surface of the injuring factor (mouthpiece, brush, pencil, etc.); it often coincides with a similar texture of the antagonist's tooth. During probing, the abrasion surfaces are smooth and almost painless (however, increased sensitivity of the hard tissues of the teeth is possible). These non-carious defects often are localized in the areas of crowns subjected to maximum loads during chewing: cutting edges, bumps, i.e., in caries-resistant areas.
Enamel erosion
Enamel erosion is an oval or rounded enamel defect located transversely on the most convex part of the anterior surface of the tooth crown. The intersection defect has a distinctive saucer-like form, and the bottom of the erosion is smooth and lustrous, with no evidence of demineralization. Erosions are virtually painless, although hypersensitivity of hard tissues is possible.
Chemical necrosis
Chemical necrosis of the enamel also leads to demineralization, pigmentation, defect, and hypersensitivity of hard tissues to chemical stimuli. It differs from caries by its favorite localization on the front teeth' vestibular surfaces and the defect's planar nature. Such damage occurs on the surfaces of the teeth in direct contact with acid or alkaline air and is often professional. Therefore, anamnestic data on the nature of the patient's work may be important.