Objective: To compare the adhesion and maturation of blood components on chemically conditioned root surfaces. Method and Materials: Clinical root samples of human teeth were obtained (n = 150) and manually scaled. Five groups of 30 samples were treated as follows: (1) saline solution irrigation (control); (2) 24% EDTA gel; (3) 25% citric acid solution; (4) tetracycline solution (50 mg/mL); and (5) 30% sodium citrate solution. After these treatments, 15 samples of each group received a blood drop and were analyzed by SEM. The remaining 15 had their surface morphology evaluated for collagen fibrils exposure by SEM. Photomicrographs were analyzed according to the score of adhesion of blood components. Kruskal-Wallis and Dunn multiple comparison tests were employed. Results: The control group was characterized by the absence of blood elements on the surface. The best result was observed in the citric acid group, which had a dense fibrin network with blood elements adhered. The EDTA group showed a moderate fibrin network formation. In contrast, a scarce fibrin network and a few cells were present in the tetracycline samples, and an absence of blood elements was found on sodium citrate specimens. The citric acid group was statistically different from the control group (P .01). No differences were found among the control, EDTA, tetracycline, and sodium citrate groups (P > .05). Conclusion: Under these experimental conditions, citric acid is indicated to stabilize clots on the root surface, which act as a scaffold for connective tissue cell development. Keywords: clot, fibrin, periodontal diseases, periodontal therapy, scanning electron microscopy, smear layer, tooth root