ROOT RESORPTION

Several different types of resorption are recognised: some are isolated to one tooth and slow spreading, others are rapid, aggressive and may involve several teeth. Resorption is initiated either from within the pulp, giving rise to internal resorption, or from outside the tooth, where it is termed external resorption.
The aetiology of resorption has been described by Tronstad who also presented a new classification.

In Tronstad s view, the permanent teeth are not normally resorbed, the mineralised tissues are protected by predentine and odontoblasts in the root canal and by precementum and cementoblasts on the root surface. If the predentine or precementum becomes mineralised, or, in the case of the precementum, is mechanically damaged or scraped off, multinucleated cells colonise the mineralised or denuded surfaces and resorption ensues. Tronstad refers to this type of resorption as inflammatory, which may be transient or progressive. Transient inflammatory resorption will repair with the formation of a cementum-like tissue, unless there is continuous stimulation.

Transient root resorption will occur in traumatised teeth or teeth that have undergone periodontal treatment or orthodontics. Progressive resorption may occur in the presence of infection, certain systemic diseases, mechanical irritation of tissue or increased pressure in tissue.