Differences in histochemical characteristics of gingival collagen after ER: YAG laser periodontal plastic surgery

Objective: The aim of this study is to evaluate gingival collagen for the e ffect of treatment with the Erbium:YAG Kesler handpiece. The handpiece is d esigned for gingival resurfacing in cases of hypertrophic gingiva and gingi val pigmentation. Background Data: Lasers represent recent technological ad vances that afford new options for the treatment of periodontal diseases. H owever, lasers used for esthetic gingival soft tissue resurfacing require c areful histopathological evaluation of the effects on tissue. In particular , it is important to determine the effect of laser irradiation on connectiv e tissue, especially the collagen fibers. To date, no stage-wise clinical o r histological studies have been performed addressing this issue. Methods: Ten patients underwent irradiation with the following parameters: energy pe r pulse, 500 mJ; repetition rate, 10 pps; spot size, 3 mm. Gingival biopsy specimens were derived from 6 patients with hypertrophic gingiva and 4 with gingival pigmentation. The patients were examined before laser treatment a nd at 7 and 14 days after laser treatment. The tissues were fixed in lymph node revealing solution (LNRS), embedded in paraffin, sectioned at 5 Ecm, a nd stained with hematoxylin & eosin. The status of collagen in the treatmen t site was examined under polarized light after picrosirius red (PSR) stain ing. PSR is a collagen stain that differentiates collagen fiber density or size by means of a spectrum of color changes under polarized light. The maj or colors are red, orange, yellow, and green. Results: We found a significa nt difference in the properties of collagen fibers at the first week and at 14 days post-treatment. In the normal gingiva, the predominant polarizatio n colors were in the red-orange range, signifying tightly packed, mature co llagen. During the first postoperative week, collagen fibers exhibited pola rization colors in the green to green-yellow range, implying loosely packed collagen fibers. After 2 weeks, collagen fibers reacquired their preoperat ive PSR characteristics. Conclusions: We conclude that sequential series of changes accompany photothermal treatment of the gingiva. The occurrence of this sequence in all successful outcome cases may suggest the importance o f these temporally sequenced changes in collagen during gum healing. In any event, the status of PSR staining of gum collagen provides a useful adjunc t in the assessment of gingival health.