Abstract
ObjectiveTo observe dynamic changes in root resorption repair, tooth movement relapse and alveolar bone microstructure following the application of orthodontic force.Materials and MethodsForces of 20 g, 50 g or 100 g were delivered to the left maxillary first molars of fifteen 10-week-old rats for 14 days. Each rat was subjected to micro-computed tomography scanning at 0, 3, 7, 10, 14, 28 and 42 days after force removal. The root resorption crater volume, tooth movement relapse and alveolar bone microarchitecture were measured at each time point.ResultsFrom day 3 to day 14, the root resorption volume decreased significantly in each group. In the 20-g force group, the root resorption volume gradually stabilized after 14 days, whereas in the 50-g and 100-g force groups, it stabilized after 28 days. In all groups, tooth movement relapsed significantly from day 0 to day 14 and then remained stable. From day 3 to day 10, the 20-g group exhibited faster relapse than the 50-g and 100-g groups. In all groups, the structure model index and trabecular separation decreased slowly from day 0 to day 10 and eventually stabilized. Trabecular number increased slowly from day 0 to day 7 and then stabilized.ConclusionsThe initial stage of root resorption repair did not change significantly and was followed by a dramatic repair period before stabilizing. The most serious tooth movement relapse occurred immediately after the appliance was removed, and then the tooth completely returned to the original position.
Highlights
Root resorption usually occurs during or after orthodontic treatment and is known as orthodontically induced root resorption (OIRR) [1]
Micro-CT and OIRR Repair occurred immediately after the appliance was removed, and the tooth completely returned to the original position
Brudvik reported that when orthodontic force was removed or reduced to below a certain level, the root cavity could self-heal to a certain extent [4]
Summary
Root resorption usually occurs during or after orthodontic treatment and is known as orthodontically induced root resorption (OIRR) [1]. Many qualitative studies have evaluated resorption repair using laser microscopy, scanning electron microscopy (SEM), transmission electron microscopy and histologic staining, but all of these studies share several common disadvantages [8,9] In these studies, animals were sacrificed at a particular time point, and the obtained results were discontinuous and stationary; these methods cannot sequentially assess the root resorption repair process. Animals were sacrificed at a particular time point, and the obtained results were discontinuous and stationary; these methods cannot sequentially assess the root resorption repair process These methods require complex procedures, and tissue loss occurs during the preparation of paraffin-embedded sections. These methods lack measurement precision, and a new approach is needed to observe dynamic changes in root resorption craters during tooth movement
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