title: New methodology for evaluating osteoclastic activity induced by orthodontic load.
abstract: Orthodontic tooth movement (OTM) is a dynamic process of bone modeling involving osteoclast-driven resorption on the compression side. Consequently, to estimate the influence of various situations on tooth movement, experimental studies need to analyze this cell. Objectives The aim of this study was to test and validate a new method for evaluating osteoclastic activity stimulated by mechanical loading based on the fractal analysis of the periodontal ligament (PDL)-bone interface. Material and Methods The mandibular right first molars of 14 rabbits were tipped mesially by a coil spring exerting a constant force of 85 cN. To evaluate the actual influence of osteoclasts on fractal dimension of bone surface, alendronate (3 mg/Kg) was injected weekly in seven of those rabbits. After 21 days, the animals were killed and their jaws were processed for histological evaluation. Osteoclast counts and fractal analysis (by the box counting method) of the PDL-bone interface were performed in histological sections of the right and left sides of the mandible. Results An increase in the number of osteoclasts and in fractal dimension after OTM only happened when alendronate was not administered. Strong correlation was found between the number of osteoclasts and fractal dimension. Conclusions Our results suggest that osteoclastic activity leads to an increase in bone surface irregularity, which can be quantified by its fractal dimension. This makes fractal analysis by the box counting method a potential tool for the assessment of osteoclastic activity on bone surfaces in microscopic examination.
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Adriele Silveira
authors.initials: AS
authors.lastname: Araújo
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Alline Birra Nolasco
authors.initials: AB
authors.lastname: Fernandes
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: José Vinicius Bolognesi
authors.initials: JV
authors.lastname: Maciel
authors.affiliation: Department of Oral Pathology and Oral Diagnosis, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Juliana de Noronha Santos
authors.initials: Jde N
authors.lastname: Netto
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Bolognese
mesh_terms: D019386:Alendronate / Q000494:pharmacology; D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology*; D017709:Fractals; D007091:Image Processing, Computer-Assisted; D008297:Male; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology*; D010513:Periodontal Ligament / Q000033:anatomy & histology* / Q000502:physiology; D011817:Rabbits; D015203:Reproducibility of Results; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000379:methods*
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate