Luxation Injuries and External Root Resorption-- Etiology, Treatment, and Prognosis

When a tooth sustains a luxation injury, attachment damage of varying degrees will occur. In addition, necrosis of the pulp might result, thereby making the pulp space susceptible to infection. Unlike root resorption in primary teeth, which occurs predictably when the permanent tooth erupts, resorption in permanent teeth will occur only under pathologic conditions. This fact appears to be due to the anti-resorptive properties of the precementum covering of the root that protects it in the presence of inflammation (Figure 1). However, if a luxation injury removes or alters the precementum, the inflammatory response will include root resorption with multinucleated clastic cells in addition to the "usual " bone resorption. Thus, for root resorption to occur, two circumstances must exist: a change must have occurred to the protective attachment layer (precementum externally) of the root and an inflammatory process must be present adjacent to the damaged root surface. Treatment strategies for root resorption include preventing it by recognizing the causes of the root surface injury and avoiding them; minimizing initial inflammation and thus the resorptive consequences by manipulating the inflammatory response; and reversing resorption by eliminating the inflammatory stimulator. External Root Resorption Due to the Injury Alone The luxation injury is the cause of the attachment damage. The byproducts of this mechanical damage stimulate the inflammatory response. The type of tissue that will cover the damaged root surface depends upon the extent of the initial damage. When a tooth sustains a luxation injury, attachment damage of varying degrees will occur. In addition, necrosis of the pulp might result, thereby making the pulp space susceptible to infection. These circumstances can lead to root resorption. Treatment for root resorption includes preventing it by avoiding causes of root surface injury, minimizing initial inflammation, and reversing resorption