Gingival invagination in extraction sites of orthodontic patients: their incidence, effects on periodontal health, and orthodontic treatment.

Incomplete adaptation of supporting structures during orthodontic closure of extraction spaces may result in invagination of the gingiva in this area. This study was undertaken to determine the incidence and possible association of these structural changes with gingival health and stability of extraction-space closure. Three groups of twenty-four orthodontic patients who had first premolars removed were examined at different stages of treatment: space closure complete, in retention, and postretention. The location, and severity of invaginations were recorded. The overall and extraction area gingival health, width of attached gingiva, and tightness of contacts in that area were assessed. The canine inclination at the various stages of treatment was measured from panoramic radiographs. The data were analyzed via comparison of means, Pearson's correlation coefficient, and ANOVA. Results indicated a very high incidence of invaginations forming during extraction-space closure. Invaginations were more frequent, complex, and severe in the mandibular arch than in the maxillary arch (p less than 0.001). The width of attached gingiva, overall gingival health, and canine inclination were not consistently related to their formation. The general trend was toward some resolution of these defects with time, but many persisted years after retention was discontinued. There was no evidence of an association with reopening of extraction space (p greater than 0.05). The presence and severity of gingival invaginations were consistently related to a reduction in gingival health in that area (p less than 0.001), regardless of the phase of treatment.