The role of keratinized gingiva in plaque-associated gingivitis in dogs

Abstract The present experiment was designed to examine if a dento-gingival unit with a wide zone of keratinized gingiva (KG) provides a more efficient seal against plaque infection than a unit with a narrow zone of KG or lack of such gingiva. Five beagle dogs were used. In a preparatory experiment three categories of gingival units were established in each dog, namely (1) regenerated gingiva with a wide zone of KG (healed following a “flap” procedure), (2) regenerated gingiva with an “insufficiently” wide zone of KG (healed following a “gingivectomy” procedure), and (3) non-operated control gingiva with a normal zone of KG. Clinical and histological examinations carried out at the end of the preparatory period revealed that all gingival units, non-operated as well as regenerated units, met the criteria of health. All tooth-cleaning measures were abolished. After 40 days of plaque accumulation the clinical examination (Plaque Index, Gingival Index and Gingival Exudate) was repeated and biopsies were sampled. Following preparation the biopsy material was subjected to histometric and morphometric analysis. The results showed that the free gingiva of units with wide and narrow zones of KG responded to microbial colonization by an inflammatory reaction, the location and extension of which did not vary with the width of the keratinized gingiva. It was concluded that, in the presence of plaque, a dento-gingival unit with a narrow zone of, or with lack of, gingiva has an equal capacity for inflammatory response against plaque infection as a unit with a wide zone of KG.