Misaligned teeth, also known as malocclusion, refers to the deformities of teeth, jawbones, and craniofacial structures in children during growth and development. These deformities can be caused by either genetic factors or environmental factors such as diseases, poor oral habits, abnormal tooth replacement, etc. The main types include misaligned teeth arrangement, abnormal occlusal relationship between upper and lower dental arches, and abnormal size, shape, and position of the jawbone. The formation factors and mechanisms of malocclusion are complex. The occurrence process may be influenced by a single factor or mechanism, but it could also be the result of multiple factors or mechanisms acting together. These factors affect the growth and development of bones, nerves, muscles, teeth, and soft tissues in the jaw and face, leading to abnormal changes that subsequently cause malocclusion.
The etiological factors of malocclusion generally fall into two major categories: hereditary factors and acquired factors. Hereditary factors mainly involve racial evolution and degeneration, accounting for about 30% of the causes. Acquired factors include the following aspects:
(1) Premature loss of deciduous teeth: This can lead to insufficient space, resulting in crowded and misplaced teeth. Losing the guiding role for permanent teeth eruption can cause misalignment or failure of eruption.
(2) Bad habits: Common habits include thumb sucking, tongue thrusting, lip biting, object biting, mandibular protrusion, improper swallowing, and unilateral chewing, which can cause various types of malocclusions.
(3) Supernumerary teeth: These can lead to morphological and functional disorders in the tooth-jaw system; supernumerary central incisors can cause gaps between central incisors.
(4) Congenital missing teeth: Often due to developmental and embryonic reasons, the absence of third molars is usually a sign of evolutionary degeneration.
(5) Deciduous teeth retention: When certain deciduous teeth fail to shed on time, it leads to retention, which can block the eruption of permanent teeth, causing them to remain impacted or erupt in a wrong position.
(6) Insufficient wear of deciduous canines: Due to overly soft food consumption by children, some deciduous canines may not wear down as much as other teeth, thus standing higher above the dental arch surface, causing early contact, leading to anterior or lateral movement, and forming crossbite.
(7) Additionally, there are many systemic and local disease factors, such as infectious diseases, malnutrition, endocrine factors, vitamin deficiency, cleft lip and palate, benign hypertrophy of the mandibular condyle, facial gigantism, etc.