A previous study demonstrated that the bleeding on probing (BOP) test using uncontrolled forces may result in a proportion of false positive readings when used as a parameter for inflammation. A strong possibility exists for the traumatization of clinically healthy gingival tissues if a probing force exceeding 0.25 N is applied. While these results originated form young dental hygienists exhibiting excellent oral hygiene, the aim of the present study was to evaluate the relationship between probing pressures and gingival conditions in patients with a history of treated periodontal disease, i.e., in situations with a reduced but healthy periodontium. 10 patients who had been enrolled in a periodontal maintenance program following treatment of moderate to advanced chronic inflammatory periodontal disease consented to participate in the study. They were all selected on the basis of a record of excellent oral hygiene practices for at least 2-6 years and almost complete absence of clinical inflammation following successful periodontal therapy. Applying a probing force of 0.125, 0.25, 0.375 and 0.5 N in the 4 jaw quadrants, respectively, at 2 different occasions with an interval of 10 days, bleeding on probing was assessed. Oral hygiene and gingival conditions were determined using the criteria of the plaque and gingival index systems. All subjects showed significant increases in mean BOP% with increasing probing force applied (2.5%-7.9%). Regression analysis revealed an almost linear correlation and a significant correlation coefficient between BOP% and probing force. Almost identical slope inclinations were found when the 6 subjects with the lowest mean BOP% at 0.25 N were compared with the regression analysis of the total group.(ABSTRACT TRUNCATED AT 250 WORDS)