Inclusion Criteria:  Adult patients, over 18 years old. In need of removal of a maxillary or mandibular molar first or second molar. The molars to be extracted had to be bordered by at least one tooth. The molars had to have a presence of > 2 mm of keratinized gingiva and three intact bony walls. A dehiscence on the fourth wall, if any, had to be equal or less than 2 mm in height. Only one extraction per patient was accepted.  Exclusion Criteria:  Acute periodontal or periapical infection. Pregnancy or lactancy. Smokers of more than 10 cigarettes per day. Previous adverse reactions to the biomaterials used in the study. Metabolic diseases affecting the mechanism of bone remodelling. Medications or treatments taken in the last twelve months and known to affect bone "turnover". Patients with poor plaque control -more than 20% (O'Leary, Drake, Naylor, 1972). Patients with absence of periodontal health maintenance or postoperative recommendations compliance.