Developmental Disturbances of Permanent Teeth after Trauma to their Predecessors

Although traumatic injuries to the primary teeth are common, few studies have analyzed the prognosis of these injuries with respect to damage to the permanent tooth germ. Objectives: The objective of this follow-up study was to evaluate the incidence of posttraumatic developmental disturbances in permanent teeth after trauma of their predecessors using a specific index. Furthermore the relationship between type of trauma and eruption disturbances have been investigated. Materials and Methods: 89 permanent teeth in 49 children, who had been treated in a private practice between 1990 and 2000 due to a trauma to the primary dentition, have been evaluated clinically and radiographically as for posttraumatic developmental disturbances. They have been rated using a specific index that distinguishes the extent of hypoplasia (0 - no hypoplasia; I - hypoplasia with aplastic defect of enamel; II - hypoplasia with aplastic defect of enamel and dentin; III - malformation) and discoloration (a - no discoloration; b - white opacities of the enamel; c - yellow-brownish discoloration of the enamel). Results: 33 of the permanent teeth showed developmental disturbances following injuries to their primary predecessor. All teeth affected were incisors. According to the classification by the index, two main groups have been identified. One group predominantly presented discolorations (0b/0c) and a second group was more affected by a distinct hypoplasia (Ia/IIa). There were only few cases showing both of these symptoms. Sequelae of trauma were related to age and type of trauma. In case trauma occured during the initial stages of development mineralization was disturbed. In later stages, eruption disturbances were predominant. Conclusion: Age and the specific type of injury to the primary dentition are the most important parameters in determining the type and extent of developmental disturbances in the permanent successor after trauma.