(1) Biological factors and individual factors:
① Age factor: Older people are more likely to have dental root resorption than younger people.
② Gender factor: Females are more prone to dental root resorption than males.
③ Dental factors: Teeth with flat root tips and short roots, embedded canines, and deformed teeth are prone to dental root resorption; Anterior teeth are more prone to dental root resorption than posterior teeth. Tooth position: The maxillary central incisor is most likely to have the dental root resorption. During the orthodontic therapy, the sequence of susceptible teeth is: Maxillary central incisor, maxillary lateral incisor, mandibular incisor, mandibular first molar distal root, mandibular second premolar and maxillary second premolar.
④ Individual sensitivity.
⑤ Some other systemic diseases.
(2) Mechanical factors:
The adducent anterior teeth are more likely to have dental root resorption than elevated, depressed, abducted, and moving teeth; The obliquely moving teeth are more likely to suffer from dental root resorption than the overall moving teeth; The continuous force is easier to produce dental root resorption than the discontinuous force; Strong orthodontic force is more prone to dental root resorption than light force.
The dental root resorption is unpredictable. Before the orthodontic therapy, patients and their families must be informed in advance that the dental root resorption may occur after the orthodontic therapy, and its occurrence is unpredictable.
Clinically, the most helpful method for predicting dental root resorption is to take X-rays before the orthodontic therapy. If the dental root resorption is found through X-ray examination before correction, special attention should be paid during the correction process. The resorption is often intensified after the correction force is applied. Not only the cementum resorption in the compressed area will be stepped up, but also the deep dentin is affected. The factors that help prediction include the shape of the tooth root, the developmental stage of the tooth root and so on.
(1) X-rays should be regularly reviewed regularly. Among them, the parallel projection apical film can reflect the root problem more accurately than the apical film and the curved tomographic film.
(2) The orthodontic therapy should be carried out during the growth and development period; Use weak and intermittent correction force; Avoid excessive continuous force; Try to avoid tilting, moving and depressing the teeth; And shorten the correction time as much as possible.
(3) When it is found that the dental root resorption exceeds 1/4 of the root length, temporarily interrupt the treatment and change the original treatment plan to avoid serious root resorption.