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.

Zoledronic acid and alendronate sodium and the implications in orthodontic movement

“…The BPs also inhibit the recruitment of these cells, such as seen in the osteoclast count in our study. Several experimental studies have observed the interference of BPs in the differentiation and activity of osteoclasts …”

Effects of Photobiomodulation on SOFAT, A T‐cell‐derived Cytokine, May Explain Accelerated Orthodontic Tooth Movement

“…The complexity of the alveolar bone interface was measured for evaluating osteoclastic activity induced by tooth movement. Mechanical load increases alveolar bone surface irregularity due to the resorption promoted by osteoclasts on the pressure side, and this irregularity could be measured by fractal analysis as previously proposed .…”

Effect of the leukotriene receptor antagonist montelukast on orthodontic tooth movement

“…Large multinucleated cells with eosinophilic cytoplasm were considered osteoclasts when present on the bone surface or in bone-resorptive lacunae (15). Osteoclast activity was classified as 0: no activity, if no osteoclasts were found, 1: low, if one to five osteoclasts were found, 2: moderate, if six to 10 osteoclasts were found, and 3: high, if more than 10 osteoclasts were found.…”