Long-term gingival conditions after orthodontic closure of extraction sites. Histological and histochemical studies.

Abstract

To evaluate the long-term gingival tissue changes following orthodontic space closure, biopsies comprising gingival papillae were taken in nine patients from maxillary premolar extraction sites from 0 to 15 months after closure by edgewise appliances. Histomorphological examination, a chemical component histochemical investigation and an enzyme histochemical analysis were performed. Clinically the initial moderate gingival hyperplasia disappeared within a few months but an induced invagination remained and in these areas deep proliferations of the oral epithelium were found histologically. The surrounding connective tissue sometimes exhibited loss of collagen. These changes indicate permanent damage to the gingival tissues. The same histological and histochemical picture was obtained irrespective of time after closure of the extraction site. The papillae were excised a second time to evaluate the results of the earlier papillectomy. The second biopsy showed almost unchanged hyperplastic epithelial reactions and invaginations but development of a more ‘mature’ connective tissue in the papillary area evidently more resistant to inflammation. Removal of gingival papillae in closure sites seems to favour restitution of a more normal connective tissue.