Normally, there is a considerable intra-individual and inter-individual variation in both width and thickness of the facial gingiva, a fact that gives rise to the assumption that different gingival phenotypes might exist in any adult population. The bulky, slightly scalloped marginal gingiva with short and wide teeth on one hand and the thin, highly scalloped marginal gingiva with slender teeth on the other may serve to illustrate the existence of markedly different periodontal entities or so-called ‘‘gingival biotypes’’. The identification of the gingival biotype may be important in clinical practice since differences in gingival and osseous architecture have been shown to exhibit a significant impact on the outcome of restorative therapy. GCF plays a special part in maintaining the structure of junctional epithelium and the antimicrobial defense of periodontium. Understanding physical and chemical aspects of the gingival crevice microenvironment is essential for a comprehensive periodontal health evaluation. In this respect, gingival crevicular pH has been considered an indicator of periodontal health status and studied since 1954. It may play an important role in physiological and biochemical activities of the gingival crevice. In plaque-associated periodontal disease, crevicular pH is presumed to be influenced by changes in the microbial flora and proteinaceous metabolites, which produce inflammation in periodontal tissue. Many investigators have measured the crevicular pH and reported a relationship between pH and periodontal disease. This Randomized controlled clinical study aims to investigate the correlation between pH of gingival crevicular fluid and different types of gingival biotypes in healthy individuals.