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Browsing by Subject "Root resorption"
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Item In vivo microcomputed tomography evaluation of rat alveolar bone and root resorption during orthodontic tooth movement(Allen Press, 2013) Ru, Nan; Liu, Sean Shih-Yao; Zhuang, Li; Li, Song; Bai, Yuxing; Orthodontics and Oral Facial Genetics, School of DentistryObjective: To observe the real-time microarchitecture changes of the alveolar bone and root resorption during orthodontic treatment. Materials and Methods: A 10 g force was delivered to move the maxillary left first molars mesially in twenty 10-week-old rats for 14 days. The first molar and adjacent alveolar bone were scanned using in vivo microcomputed tomography at the following time points: days 0, 3, 7, and 14. Microarchitecture parameters, including bone volume fraction, structure model index, trabecular thickness, trabecular number, and trabecular separation of alveolar bone, were measured on the compression and tension side. The total root volume was measured, and the resorption crater volume at each time point was calculated. Univariate repeated measures analysis of variance with Bonferroni corrections were performed to compare the differences in each parameter between time points with significance level at P < .05. Results: From day 3 to day 7, bone volume fraction, structure model index, trabecular thickness, and trabecular separation decreased significantly on the compression side, but the same parameters increased significantly on the tension side from day 7 to day 14. Root resorption volume of the mesial root increased significantly on day 7 of orthodontic loading. Conclusions: Real-time root and bone resorption during orthodontic movement can be observed in 3 dimensions using in vivo micro-CT. Alveolar bone resorption and root resorption were observed mostly in the apical third on day 7 on the compression side; bone formation was observed on day 14 on the tension side during orthodontic tooth movement.Item Pathways in external apical root resorption associated with orthodontia(Wiley, 2009-08) Hartsfield Jr., J.K.; Department of Orthodontics and Oral Facial Genetics, IU School of DentistryTo review studies investigating if genetic factors play a role in external apical root resorption (EARR) during orthodontic treatment. Heritability estimation in human sib-pairs, comparison of multiple inbred mouse strains, human sib-pair linkage and parents-child trio association studies, and two gene (Il-1b, and P2rx7) knock out mouse models. Heritability for EARR of the maxillary central incisors concurrent with orthodontic treatment is 0.8. DBA/2J, BALB/cJ, and 129P3/J inbred mouse strains are highly susceptible (p < .05) to histological root resorption (RR) associated with orthodontic force (RRAOF), whereas A/J, C57BL/6J and SJL/J mice are resistant. Non-parametric sibling pair linkage analysis identified evidence of linkage (LOD = 2.5; p = 0.02) of EARR with microsatellite D18S64 (tightly linked to TNFRSF11A, also known as RANK). There is significant linkage disequilibrium of IL-1B (p = 0.0003), and OPG (p = 0.003) with EARR. RRAOF increases in Il1b KO (p < or = 0.013), and increases in P2rx7 KO (p < 0.02) mice compared to wild-type. Genetic factors play a marked role in EARR concurrent with orthodontic force, accounting for one-half to two-thirds of the variation. Two pathways for this may involve: 1) activation control of osteoclasts through the ATP/P2XR7/IL-1B inflammation modulation pathway; and 2) RANK/RANKL/OPG osteoclast activation control. Histological RR occurs and is typically healed. If resorption outpaces healing, then EARR develops. Normal and parafunctional forces, as well as orthodontic forces, may add to or interact with the individual's susceptibility to pass the threshold of developing EARR.Item A proposed mechanism for non-carious cervical lesions, root resorption and abutment screw loosening(2022-01-13) Katona, Thomas R.; Eckert, George J.Objectives The purpose of this paper is to present a mechanism for the shared etiologies of non-carious cervical lesions (NCCLs), orthodontics-associated root resorption and implant abutment screw loosening. These are persistent clinical problems with equivocal etiologies. Methods A matched pair of 1st molar denture teeth was set into occlusion within a testing apparatus. The weighted maxillary assembly, guided by slides, was cyclically lowered onto, and raised from, the mandibular tooth. The forces and moments on the mandibular tooth were continuously recorded by a load cell. The maxillary crown was rigidly fixed (ankylosed or implant supported). The mandibular tooth was rigidly fixed or supported by a PDL analogue. For statistics, 21 occlusal relationships were tested. Results The measurements confirmed earlier non- and counter-intuitive results. The directly relevant data were that the measured loads on the tooth, during the span of an individual chomp, are characterized by a wide range of magnitudes and directions. Moreover, these load profiles change with rigid vs. PDL support (p = 0.001), occlusal relationship (p < 0.001) and occlusion vs. disclusion (p = 0.002). Conclusion The demonstrated transient loads within the span of a single chomp produce complex mechanical environments. Thus, it is proposed that NCCLs, orthodontic root resorption and abutment screw loosening result from load component combinations, not from solitary occlusion forces as typically applied in experimental and numerical investigations. In principle, the loading combination concept applies to all phenomena that involve occlusal contacts, including occlusal trauma, implant loading, jaw fracture repairs, etc.Item Root resorptions associated with canine retraction treatment(Elsevier, 2017-09) Jiang, Feifei; Chen, Jie; Kula, Katherine; Gu, Huiying; Du, Yansheng; Eckert, George; Mechanical and Energy Engineering, School of Engineering and TechnologyINTRODUCTION: The hypothesis of this study was that multiple factors are dominant in causing external apical root resorption (EARR). The objective of this investigation was to better understand the clinical factors that may lead to EARR. METHODS: Maxillary cone-beam computed tomography scans of 18 subjects who were treated with bilateral canine retractions during orthodontics were used to calculate EARR. The subjects were treated using well-calibrated segmental T-loops for delivering a 124-cN retraction force and the moment-to-force ratio suitable for moving the canine under either translation or controlled tipping. The subjects' age, sex, treatment duration, and genotype were collected. RESULTS: Six subjects of the 18 showed definite EARR, meaning that load was not the only causing factor. All 5 subjects with the genotype identified had GG genotype of IL-1β rs11143634, indicating that people with this genotype may be at high risk. Longer treatment duration, female sex, and older age may also contribute to EARR, although the findings were not statistically significant. CONCLUSIONS: EARR appears to be related to multiple factors. The orthodontic load and the genotype should be the focuses for future studies.