Anomalies of tooth development

X-ray examination of congenital and acquired deformities of the maxillofacial region

Deformations of the maxillofacial area occur when the shape, size and relationship of individual bone components change. They can be congenital (chromosomal diseases, the impact of teratogenic factors on the fetus) and acquired (after childhood illnesses, injuries, radiation therapy, endocrine and metabolic disorders, etc.).

According to the WHO classification (IX revision), there are:

• an increase in all or parts of the jaw (upper or lower) - macrognathia;
• reduction of all or parts of the jaw (upper or lower) - micrognathia;
• misaligned jaws in relation to the base of the skull - displacement in the sagittal, vertical or transversal direction;
• deformations including those listed above.

Anomalies of teeth and jaws occur in 30% of school-age children. Anomalies of jaws, as a rule, are accompanied by malocclusion.

Anomalies of tooth development

Common anomalies of permanent teeth are manifested in a change in their number, position, size, shape and structure.

The number of teeth can be reduced (adentia) or increased (hyperdentia) in comparison with the norm. The reasons for this are the same as those causing the deformities of the maxillofacial region. X-ray examination is shown in all cases of missing teeth in the dentition in order to establish the presence of rudiments of dairy and permanent teeth. According to the radiographs, it is also possible to determine the reasons for the delay in their eruption.

Adentia is more often observed in a permanent bite, less often in a temporary bite. The most common is the congenital absence of lateral incisors of the upper jaw and wisdom teeth, lower and upper second premolars.

Partial or complete adentia occurs in ectodermal dysplasia, a hereditary disease associated with impaired ectoderm development. The remaining individual teeth have conical crowns. In patients, the skin is smooth, atrophic, there are no sweat and sebaceous glands, nail development is disturbed, there is a prominent forehead, saddle nose, thick lips, because of aplasia of parenchyma of the salivary glands - xerostomia.

With a congenital increase in the number of teeth, the supercomplete tooth can be normally developed or rudimentary, located in the dentition or out of it. Dairy overcomplete teeth have the same shape as the complete ones, and permanent ones are usually atypical. Sometimes supercomplete teeth do not erupt and they are found by chance on radiographs performed on a different occasion. Superflex teeth are more common in the lower incisors, often the fourth large molars (fourth molars) are observed.

Incorrect position of the tooth in the dentition (from the buccal or lingual side), turning the tooth around the axis, placing the crown of the tooth below the chewing surface of adjacent teeth is determined during clinical examination. X-ray examination is indispensable for assessing the position of the tooth in the jaw. The spacing between adjacent teeth is called a trema. Absence of three in children of 5 years of age indicates a delay in the growth of the jaw. Thremium with a width of 0.5-0.7 mm is considered a variant of the norm. The interval between the central incisors in the width of 0.6-7 mm was called "diastema".

The dimensions of the teeth can be reduced (microden) or enlarged (makrodentiya). This concerns one, several or all of the teeth. Chisels often change. Macrodentia of all teeth is one of the symptoms of pituitary diseases.

The most common anomalies in the development of the roots of permanent teeth - curvature, shortening or elongation, increase or decrease in their number, divergence and convergence, bifurcation. The shape and number of roots of the lower molars, especially the third ones, are most variable.

The shape of all teeth varies with cretinism and ectodermal dysplasia. Observed with congenital syphilis, the central incisors of a barrel-like shape with a semilunar incision along the cutting edge are called the Getschinson's teeth (after the English doctor J. Hutchinson's name).

Intrauterine teething was observed in only one in 2000 newborns. In 85% of cases in the uterus the central lower incisors erupt,

Ankylosis - fusion of root cement with bone tissue of the alveolus - develops after the use of formalin-resorcinine method, trauma, rarely - in second molar molars. In view of the absence of a periodontal gap occupied by the bone tissue, percussion of the ankylosing tooth is marked by a more obtuse sound. When removing such teeth, significant difficulties arise.

Tooth in the tooth (dens in dente) : in the tooth cavity and the broad root canal is a tooth-like formation surrounded by a band of enlightenment around the periphery.

One of the types of anomalies is the adhesion of adjacent teeth to each other - fused teeth. Most often there is a fusion of the central incisor with the lateral or one of them with an extra-large tooth. When splitting the enamel organ, two crowns are formed with one root. Fusion of teeth in the root region can only be determined radiologically. When merging the crowns, they have one large tooth cavity and two channels. If only the roots have merged, then there are two cavities of the tooth and two root canals. In the presence of enlarged teeth, there is a lack of space in the dentition: the teeth located next to it erupt later and, as a rule, on the lingual or buccal side.

If there is no tooth in the dentition to the period of its eruption (fluctuations in the range of 4 to 8 months from average terms are permissible), it is necessary to perform radiographs in order to determine if there is a rudimentary tooth. When analyzing the roentgenogram, it is also possible to establish the cause of the eruption delay (retention): an incorrect position of the tooth due to the displacement of the rudiment (dystopia), the presence of a pathological process (fracture, osteomyelitis, cyst, neoplasm). The most common cause of retention is a lack of space in the dentition. The rudiments of the teeth may be far from their usual location (in the branch or at the base of the lower jaw, in the walls of the maxillary sinus), and their eruption becomes impossible. The retina tooth can cause displacement and resorption of the roots of adjacent teeth.

Most often observed retention of wisdom teeth (mostly lower), canines (mostly upper), less often - premolars (upper). When planning the removal of a retouched or dystopic tooth, there is a need to determine its position and relationship with the nasal cavity, maxillary sinus, mandibular canal, roots of adjacent teeth. To solve this problem, it is necessary to perform X-ray diffraction in at least two mutually perpendicular projections.

When examining the teeth of the lower jaw, intraoral x-rays and extraoral X-rays in the axial projection are performed. To determine the position of the retaned teeth of the upper jaw, in addition to the intraoral roentgenograms (contact or axial), the most informative images are in tangential projections.

Imperfect dentinogenesis (dentinogenesis imperfecta) is a congenital disease (Steynton-Capdepone syndrome); occurs as a result of dysplasia of connective tissue, sometimes combined with imperfect osteogenesis. In diseased children, the facial part of the skull is much less cerebral, for a long time the fontanelles and seams remain unbroken, the bones of the skull are thinned. With a normally formed enamel, the structure of the dentin is broken (less mineral salts, less tubules and they are wider, their direction is changed). Such teeth are rarely affected by tooth decay. At the same time there is an early progressive erasure of the teeth right up to the gums. On the roentgenogram, a decrease in size or total obliteration of the tooth cavity and root canals is determined due to the formation of a substitute dentin. Root canals are not detected or visible only at the apex of the root. In view of the fact that the roots are usually thinner, the risk of their fractures in the trauma is higher. The color of the teeth is blue-brown, purple or amber.

[1], [2], [3], [4], [5], [6]