Etiological factors are endogenous and exogenous. The endogenous factors are divided into hereditary and disturbance of gland functions (endocrine). Exogenous factors are as follows: prenatal, neonatal, and postnatal.
Etiologic factors of defects of teeth and dentition in children and adolescents
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Hereditary factors
A child inherits various characteristics after his parents, including the structure of the dental system (the size and shape of teeth, a jaw, especially the muscular system, functions, structure).
Examples of hereditary factors.
► Anomalies in the structure of hard dental tissues (hypoplasia and aplasia of enamel, imperfect enamelo-, dentinand amelogenesis, Stanton-Capdepon syndrome, etc.).
► Anomalies in size (macrodentia, microdentia, megalodentia) and shape of teeth (Hutchinson and Fournier's teeth, spiny teeth, fusion of several teeth, curvature, thickening, shortening, bifurcation of the root, etc.).
► Abnormalities in the number of teeth (hyperodontia, hypodontia, adentia) (fig. 14).
► Abnormalities in the position of teeth (vestibular, oral, distal, mesial position of teeth, supraand infraposition), tortoanomaly and transposition of teeth and the time of eruption (latejearly eruption).
► Soft tissue abnormalities (low attachment of the frenulum of the upper lip can promote the development of diastema, short frenulum of a tongue - the formation of incorrect bite, short frenulum of the lower lip - a recession of the gingiva of the lower teeth-periodontal disease) (fig. 15).
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Рис. 14. Отсутствие зачатка зуба 3.5
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Рис. 15. Диастема между центральными резцами
► Аномалии размеров челюстей (макро- и микрогнатия), положения их относительно черепа (ретрогнатия, прогнатия), нарушения смыкания зубных рядов по сагиттали, вертикали (вертикальная резцовая дизокклюзия, глубокая резцовая окклюзия и дизокклюзия).