INFLUENCE OF TOOTH INSTRUMENTATION ROUGHNESS ON GINGIVAL TISSUE-REACTIONS

HISTOLOGICAL STUDIES HAVE DEMONSTRATED a relationship between the amou nt of subgingival plaque and the magnitude and extension of gingival t issue reactions. The objective of the present study was to evaluate in flammatory reactions in the gingival tissues facing plaque accumulatio n at diamond and curet-instrumented root surfaces, Experimental, deep periodontal defects were established at buccal surfaces of mandibular and maxillary canine teeth in 5 beagle dogs, The root surfaces were in strumented by a flame-shaped, fine-grained, rotating diamond point, or by a sharp curet, Next, the dogs were fed a plaque-inducing diet for 70 days, The animals were then sacrificed, and tissue blocks of the ex perimental sites including teeth, alveolar bone, and gingival tissues were secured. The gingival soft tissue was processed for histomorphome tric analyses at 3 levels. Epithelium and connective tissue area measu rements showed no differences between the two instrumentations. Juncti onal epithelium (JE) cell. point counts exhibited a higher proportion of inflammatory cells (IC) in specimens facing diamond compared to cur et-instrumented defects. A higher proportion of IC was present within the coronal compared to the apical aspect of the JE for both instrumen tations (P < 0.05). A significant difference in IC density between ins trumentations was detected for non-infiltrated (P < 0.05), as well as for infiltrated (P < 0.01) connective tissue. The infiltrated connecti ve tissue (ICT) inflammatory cell density was significantly (P < 0.01) and positively correlated to the JE inflammatory cell density (r = 0. 75), and to area measurements of ICT (r = 0.55). The overall results d emonstrate that the character of subgingival root instrumentations sig nificantly affects gingival inflammatory reactions, most likely by inf luencing subgingival plaque formation.