Effects of topical application of inorganic polyphosphate on tissue remodeling in rat inflamed gingiva

Background and Objective: Inorganic polyphosphate [poly(P)] is a biopolymer found in almost all cells and tissues, and which promotes tissue remodeling. However, there is limited information on how poly(P) affects the connective tissue in inflamed gingiva. This study examined the effects of topical application of poly(P) on gingival connective tissue and its remodeling in a rat periodontitis model. Material and Methods: Male Wistar rats (n=36, 8wk of age) were used in this 6-wk study. The rats were divided into six groups of six rats each. The control group received no treatment. In the other groups, periodontitis was ligature-induced for 4wk. After 4wk, the rats with periodontitis were further divided into five groups, and were left untreated (periodontitis group) or subjected to topical application of oral rinses containing 0, 0.1, 1 or 5% poly(P) for 2wk. Results: The periodontitis and 0% poly(P) groups showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue than the control group (p<0.05). In contrast, groups treated with more than 1% poly(P) exhibited a lower density of polymorphonuclear leukocytes (p<0.05) and a higher density of collagen than the periodontitis and 0% poly(P) groups (p<0.05). A higher expression of fibroblast growth factor-2 was observed in the gingiva of rats treated with 1% poly(P) than in those treated with 0% poly(P) (p<0.05). Conclusion: Topical application of poly(P) may induce connective tissue remodeling, contributing to improvement of inflamed gingiva in rats.