Abstract
Orthodontic treatment in patients with no periodontal tissue breakdown vs. horizontal bone loss should be approached with caution even though it can bring significant benefits in terms of periodontal recovery and long-term success. We used the finite element method (FEM) to simulate various clinical scenarios regarding the periodontal involvement: healthy with no horizontal bone loss, moderate periodontal damage (33%) and severe horizontal bone loss (66%). Afterwards, forces of different magnitudes (0.25 N, 1 N, 3 N, and 5 N) were applied in order to observe the behavioral patterns. Through mathematical modeling, we recorded the maximum equivalent stresses (σ ech), the stresses on the direction of force application (σ c) and the displacements produced (f) in the whole tooth–periodontal ligament–alveolar bone complex with various degrees of periodontal damage. The magnitude of lingualization forces in the lower anterior teeth influences primarily the values of equivalent tension, then those of the tensions in the direction in which the force is applied, and lastly those of the displacement of the lower central incisor. However, in the case of the lower lateral incisor, it influences primarily the values of the tensions in the direction in which the force is applied, then those of equivalent tensions, and lastly those of displacement. Anatomical particularities should also be considered since they may contribute to increased periodontal risk in case of lingualization of the LLI compared to that of the LCI, with a potential emergence of the “wedge effect”. To minimize periodontal hazards, the orthodontic force applied on anterior teeth with affected periodontium should not exceed 1 N.
Highlights
Orthodontic treatment in adults is becoming increasingly sought after, but this brings additional issues that have to be properly addressed as the prevalence of periodontal disease increases with age
Together with increase of compressive stress, a change in the maximum concentration of forces appears, which moves from the central radicular area to the apical lingual area; at the same time, the area of maximum tensile stress moves from the middle of the root to the vestibular cervical area [5]. This is of particular importance in the context of a patient with periodontal damage because it requires, more often than not, the lingualization of the frontal maxillary and mandibular groups, which have become vestibularized as a consequence of the loss of support periodontium
The following considerations were taken into account: the geometry and morphology of teeth; periodontal structures and dental arches; the physical properties of teeth, periodontal ligament, and alveolar bone; and the magnitude and direction of the force used to simulate orthodontic stress on patients with periodontal damage compared to patients with unaffected periodontium
Summary
Orthodontic treatment in adults is becoming increasingly sought after, but this brings additional issues that have to be properly addressed as the prevalence of periodontal disease increases with age. Together with increase of compressive stress, a change in the maximum concentration of forces appears, which moves from the central radicular area to the apical lingual area; at the same time, the area of maximum tensile stress moves from the middle of the root to the vestibular cervical area [5]. This is of particular importance in the context of a patient with periodontal damage because it requires, more often than not, the lingualization of the frontal maxillary and mandibular groups, which have become vestibularized as a consequence of the loss of support periodontium
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