page_title: Tooth resorption
section_title: Replacement
hierarchical_section_title: Tooth resorption / Classifications / External resorption / Replacement
caption_attribution_description: Deutsch: Wurzelresorption Zahn 25 und keilformiger Defekt
context_page_description: Tooth resorption, or root resorption, is the progressive loss of dentine and cementum by the action of osteoclasts. This is a normal 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.
context_section_description: External replacement resorption occurs following ankylosis of the root of the alveolar bone. The tooth tissue is resorbed and replaced with bone. This process is poorly understood.
  It is thought that following the union of bone and tooth and the obliteration of the PDL, the protective regulators released by the PDL to protect the root from resorption are no longer present. This results in the tooth tissue being resorbed by osteoclasts and replaced with bone like it was part of the continuous homeostatic process of bone turnover.
caption: x-ray of external root resorption 25
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