Straumann Bone Ceramic Versus BioOss in Sinus Elevation

Inclusion Criteria: * Males and females, 18 years to 80 years of age * The patients are at least partly edentulous in the both maxillary regions corresponding to the sinuses. * A dental implant procedure is foreseen in both maxilla regions corresponding to maxillary sinuses. * Patients must be expected to present a bilateral bone defect in the sinus area, which both need a sinus floor augmentation to place one or more dental implants each. * Residual alveolar crest height of the lateral-posterior segments of the edentulous maxilla below the floor of each of the maxillary sinuses shall be * less than 5 mm and at least 2 mm, as measured by Scanora - tomography Scans in the deepest floor of the sinus * residual alveolar crest width should be at least in average more than 4mm as measured by Scanora - tomography scans * Patients must be committed to the study and must sign informed consent. * Oral hygiene Index less than 25% Exclusion Criteria: * Any systemic medical condition that could interfere with the surgical procedure or planned treatment * Current pregnancy at the time of recruitment * Physical handicaps that would interfere with the ability to perform adequate oral hygiene * Alcoholism or chronically drug abuse causing systemic compromize * Patients who smoke more than 10 cigarettes per day * Medication which interferes with bone formation * Conditions or circumstances, in the opinion of the investigator, which could represent a general contra-indication for surgical procedure or would prevent completion of study participation or interfere with analysis of study results, such as history of non-compliance, or unreliability * Mucosal diseases such as erosive lichen planus * History of local radiation therapy * Presence of oral lesions (such as ulceration, malignancy) * Severe bruxing or clenching habits * Persistent intraoral infection * Previous GBR (bone graft) or dental implant treatment in the posterior segments of the upper maxilla (foreseen implant site) * Patients presenting clinical and radiological signs and symptoms of maxillary sinus disease * Existing teeth in the residual dentition with untreated endodontic problems