Root resorption

Root resorption is the progressive loss of dentine and cementum by the action of osteoclasts. This is a physiological process in the exfoliation of the primary dentition, caused by osteoclast differentiation due to pressure exerted by the erupting permanent tooth. However, in the secondary dentition the process is pathological. Root resorption is the progressive loss of dentine and cementum by the action of osteoclasts. This is a physiological process in the exfoliation of the primary dentition, caused by osteoclast differentiation due to pressure exerted by the erupting permanent tooth. However, in the secondary dentition the process is pathological. Pulp necrosis, trauma, periodontal treatment, orthodontics and tooth whitening are the most common stimulants of inflammatory resorption. Some other less common causes include pressure from ectopic teeth, cysts, and tumours. These cause damage to the periodontal ligament (PDL), cementum, or pre-dentine. These tissues provide protection from resorption when intact and healthy. Regardless of the reason, tooth resorption is due to an inflammatory process in response to an insult on one of the above. Osteoclasts are the cells responsible for the resorption of the root surface. Osteoclasts can break down bone, cartilage and dentine. Osteoclast differentiation factor, osteoprotegerin ligand, receptive activator of nuclear factor kappa-B ligand (ODF, OPGL, RANKL), are all regulators of osteoclast function. In physiological bone turn over osteoblasts and stromal cells release RANK-L, this acts on macrophages and monocytes which fuse and become osteoclasts. OPG is also secreted by osteoclasts and stromal cells this inhibits RANK-L and therefore osteoclast activity.