Traumatically injured primary incisors: a clinical and histological study.

World-wide epidemiological studies state that from 8 percent to 30 percent of children up to 7 years of age sustain injury to primary incisors, including crown fracture, root fracture, tooth avulsion, and dental displacement, which result in malformation of permanent incisors depending upon their state of development. In this study, traumatized primary incisors were evaluated clinically and radiographically, with the following data recorded: exact or approximate time-interval of traumatic episode(s) and extraction, mobility, color change, sensitivity to percussion/palpation, swelling, sinus tract, caries, crown/root fracture, periodontal/periapical lesions, external/internal root resorption, mineralization, and obturation. Based upon the local damage and developmental age, 138 teeth were extracted, fixed in 10 percent formalin, and processed for histological evaluation according to routine methodology. Histologic findings were: the presence of varying extent of necrosis, bacteria in the area of necrosis--not in all cases--neutrophilic leukocytes, chronic inflammatory cells, pulpal calcifications, resorption/apposition, and circulatory changes. The blood pigment distinguished hemorrhage due to extraction from pathologic circulatory changes. All the described reactions varied in intensity and extent with the time interval and the assumed force of the original trauma. Physical trauma to primary teeth caused pulpal damage, which could involve periapical tissue, depending on the extent of the initial damage.