Clastic cells in orthodontic treatment: Translational challenges and recent advances

Objectives: Orthodontic treatment consists of numerous appliance activations that rely on stimulation of osteoclasts at alveolar bone sites. However, the action of osteoclast-like cells on dentin ("odontoclasts") is a pathological side effect of orthodontic treatment. The aim of this article is twofold: (a) To report preliminary results from ongoing cell culture experiments to identify unique markers of dentin resorption, and (b) To discuss our work using nanoparticle tracking analysis (NTA) and exosomes for developing biological fluid-based biopsies to monitor clastic cell activity.

Setting and sample population: Twelve healthy volunteers in permanent dentition.

Material and methods: For the in vitro experiments, murine clastic cell precursors were cultured on dentin or bone slices for 7 days and phage-display biopanning was used to identify molecular surface differences between osteoclasts and odontoclasts. In the human study, gingival crevicular fluid (GCF) samples were collected using different tools and analysed for protein and exosome recovery.

Results: Biopanning generated antibody fragments that were uniquely reactive to odontoclasts. Numerous nanoparticles in the size range of exosomes were detected in all of the human GCF samples.

Conclusions: Our results support that there are molecular differences between osteoclasts and odontoclasts. Emerging technologies may allow the use of exosomes in GCF as a clinical tool to detect markers of root resorption.