Recruitment and examination of the subjects were performed at the University School of Dental Medicine, Lyon, France. The study involved six clinical General Dental Practitioners (GDPs) including two private dental practitioners, a public health dentist and three dental school faculty members. The criteria for inclusion of the subjects were: age 25 to 35 years, healthy from periodontal point of view (pockets less than 2 mm), declaring at least two tooth brushings per day, with no clinically significant dental anomalies or prosthetic restoration, and accepting the study terms of reference. Periodontal biotype was not considered as an inclusion criteria. The following were excluded: subjects at risk of infection or major haemorrhage, and those with immunosuppression, diabetes, haemophilia, those taking anti-platelet or anti-coagulant agents and/or those with a history of periodontal illness or treatment, and subjects undergoing a course of dental treatment. Six subjects were selected following screening and interview.