Objectives: The distribution and size of the zone of the centres of resistance (ZCR) are critical for accurate orthodontic treatments and minimizing unexpected tooth movements. However, this information remains unclear for mandibular incisors and canines. This study aims to address these gaps in knowledge.
Methods: Finite element models of four incisors and canines from four individuals were created. Four centres of resistance (CRs) under four orthodontic directions (0° ∼ 45° ∼ 90° ∼ 135° to the sagittal plane in the horizontal plane) were assessed by a novel method. The height of the CRs was normalized to a percentage of the long axis, and the offsets were expressed as a distance value after normalization. The ZCR was obtained by fitting a 90% confidence sphere of the CR distribution. Validation was conducted to find the perturbations when the positions out of the zone were applied.
Results: The maximum variation of CR in the heights under four directions was 5.17% and 3.70% for the incisors and canines, respectively. The maximum offset between the CR and long axis was 0.14mm in incisors and 0.99mm in canines. The height of the zone in the incisor and canine was 57.75% and 59.72%, and the radius of the zone was 0.60mm and 0.65mm, respectively. The force-acting point outside the zone produced a large rotation, which was unexpected.
Conclusions: The ZCR of mandibular incisors located slightly lower than that of canines, but they were almost the same size. The ZCR was recommended as the "gold reference" for orthodontics to reduce unexpected movement.
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http://dx.doi.org/10.1016/j.ortho.2024.100933 | DOI Listing |
Vet Sci
December 2024
Department of Pathology, Division of Pathomorphology and Veterinary Forensics, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, 50-375 Wroclaw, Poland.
Filling post-extraction alveoli with hydroxyapatite-based materials is becoming an increasingly common procedure in veterinary dentistry. In dogs, tooth roots vary in structure depending on the weight of the dog, but data on tooth length and volume have not yet been described. This study aimed to establish reference data on tooth root length and post-extraction alveolar volume for mature maxillary and mandibular incisors and canines in dogs.
View Article and Find Full Text PDFJ Med Internet Res
December 2024
Kunming Medical University Affiliated Stomatological Hospital & Yunnan Key Laboratory of Stomatology, Department of Orthodontics, Kunming Medical University, C Building, Hecheng International1088 Haiyuan Middle Road, Kunming, CN.
Background: Investigating the safe range of orthodontic tooth movement is essential for maintaining oral and maxillofacial stability post-treatment. Although clear aligners rely on pre-treatment digital models, their effect on periodontal hard tissues remains uncertain. By integrating CBCT-derived cervical and root data with crown data from digital intraoral scans, a three-dimensional (3D) fusion model may enhance precision and safety.
View Article and Find Full Text PDFJ Orofac Orthop
December 2024
Paediatric Dentistry, Preclinical Dentistry Department, European University of Madrid, Madrid, Spain.
Aim: To determine whether unilateral preferent chewing (UPC) affects the position and angulation of the permanent maxillary canine germ on the preferred side.
Materials And Methods: In a retrospective cross-sectional study, medical records from children 7.91(± 0.
Front Oral Health
December 2024
Sri Ramachandra Medical College and Research Institute, Sri Ramachandra Institute of Higher Education and Research, Chennai, India.
Background: Rotations are frequently evaluated through various assessment methods of crowding and arch dimension, with relatively few studies discussing the extent or direction of rotations and even fewer addressing the reliability of such assessments. This systematic review aims to comprehensively analyze existing classification systems for rotated teeth and assess rotation in anterior and posterior teeth, its clinical applicability, and its impact on retention and relapse.
Search Methods: Two investigators conducted a comprehensive search in six databases, namely, PubMed, Scopus, Ovid, LILACS, Web of Science, and Cochrane CENTRAL, up to 28 March 2024.
Am J Orthod Dentofacial Orthop
December 2024
Piracicaba Dental School, Department of Orthodontics, Universidade de Campinas-UNICAMP, Piracicaba, São Paulo, Brazil. Electronic address:
Introduction: This study evaluated the dentoskeletal effects of miniscrew-anchored maxillary protraction, which included a mandibular anchorage bar and a night facemask in adolescents.
Methods: A total of 20 growing patients with Class III malocclusion and maxillary deficiency were treated with a hybrid hyrax expander with 2 miniscrews in the maxilla and a mandibular anchor bar supported in 2 miniscrews in the anterior region of the mandible. Class III elastics were used from the maxillary first molars to the mandibular anchorage bar, joining the mandibular miniscrews installed between permanent incisors and canines.
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