Dynamic Evaluation of Orthodontically-Induced Tooth Movement, Root Resorption, and Alveolar Bone Remodeling in Rats by in Vivo Micro-Computed Tomography

Abstract

BackgroundThe aim of this study was to dynamically evaluate tooth movement, root resorption, and remodeling of alveolar bone using different forces to cause tooth movement in rats.Material/Methods12-week-old male Sprague-Dawley rats were selected. Nickel-titanium (Ni-Ti) coil springs (20 g, 50 g, and 100 g forces) were placed for mesial movement of the left first maxillary molar teeth. Tooth movement, root resorption, and microarchitectural parameters of the trabecular bone were evaluated by in vivo micro-CT. Histological examination was used to observe the root resorption, alveolar bone remodeling, and changes in osteoclasts from day 0 to day 14.ResultsThe tooth movement distance increased significantly over the initial 3 days in the 3 groups. The 20 g force group showed more tooth movement than in the 50 and 100 g force groups after 14 days (P<0.05). From days 7 to 10, root resorption lacunae appeared in the 3 groups and then stabilized, and the 100 g force group produced more lacunar resorption than in the anther 2 groups (P<0.05). Compared to day 0, the trabecular thickness and bone volume fraction on the pressure side gradually decreased from day 7 to day 14. The structure model index increased significantly from day 3 to day 14. Histological examination showed remarkable root resorption craters and osteoclasts positive for tartrate-resistant acid phosphatase in the root resorption lacunae in the 50 g and 100 g groups from day 7 to day 14.ConclusionsA 100 g heavy force can be used to establish a root resorption model in rats.

Can implants move in bone? A longitudinal in vivo micro‐CT analysis of implants under constant forces in rat vertebrae

“…With the advent of in vivo micro-computed tomography (μCT), high-resolution scans can be obtained at different time points from the same animal (Dall'Ara et al, 2016;Li et al, 2015;Zhou et al, 2018). While metal artefacts can impede the analysis of the bone-to-implant interface and the peri-implant bone tissue, μCT is appropriate to assess positional changes of dense materials including mini-implants (Becker, Stauber, Schwarz, & Beissbarth, 2015).…”

L‐arginine protects cementoblasts against hypoxia‐induced apoptosis through Sirt1‐enhanced autophagy

“…We then conducted vivo experiments to further verify the effect of L-arg and Sirt1-enhanced autophagy on root resorption, using previously established study model. 37,38 A heavy force was applied to the first molar to establish root resorption model. One hundred grams is considered as a heavy force and is more likely to affect root absorption.…”

“…As mentioned previously, cementoblast apoptosis under hypoxic conditions may affect root resorption. We then conducted vivo experiments to further verify the effect of L‐arg and Sirt1‐enhanced autophagy on root resorption, using previously established study model 37,38 . A heavy force was applied to the first molar to establish root resorption model.…”

“…One hundred grams is considered as a heavy force and is more likely to affect root absorption. In addition, root absorption usually occurred on day seven after loading 38 . Therefore, we applied a load of 100 g to rats for 7 days to establish the root absorption model and conduct the following experiment.…”

Dynamic Changes in Tooth Displacement and Bone Morphometry in Orthodontic Tooth Movement in Rats: A 3D Analysis

“…Although the measurements became more and more accurate, the evaluation of the dynamic changes induced by OF still remains di cult, as it is hard to nd a reliable reference structure. Previous studies in rats evaluated OTM in an indirect way based on external reference structures such as the contralateral maxilla (splitmouth designs) [19,31] , the incisors [28,32] , the zygomatic arch [17] or the diastema formed between the rst and the second molar [10,15,[33][34][35][36] . However, these methods rely on those reference structures remaining stable during OTM.…”