Periodontal ligament histology for orthodontic bone remodeling: First quantification

Tooth movements are driven by biological control, mainly localized in the periodontal ligament (PDL). This biology is influenced by compression and tension of the PDL under applied external mechanical loads. The aim of this study is to histologically quantify the cellular density of fibroblasts, osteocytes, osteoblasts, osteoclasts, and vascular elements present in the PDL to use to predict tooth movements. We performed histological analyses on porcine samples, with PMMA-embedded blocks cut to a thickness of 100 μm. We measured the density of the vascular elements (av. 8.2/100 μm²), the fibroblasts in the PDL (av. 15.8/100 μm²), osteocytes (av. 8/100 μm²), osteoblasts (av. 1.8/100 μm²) in bone and multinuclear cells (av. 1/100 μm²). These data would serve to implement predictive numerical model of bone remodelling during orthodontic tooth movement. This issue has priority in orthodontics to be able to anticipate the biological reactions and thus limit the undesirable side effects.