Randomized, Controlled Study to Compare Straumann® VivOss™ to Geistlich Bio-Oss® in Sinus Floor Augmentation.

Inclusion Criteria: * Subject must have voluntarily signed the informed consent before any study related action * Males and females with at least 18 years of age (including 18 years) * Subject needs augmentation procedure in the sinus to prepare for implant placement. * Subject must have a residual bone height of 2 to 4 mm. * Adequate oral hygiene ((Full mouth plaque index (O'Leary, et al. 1972 ) \<25%) at baseline * Adequate control of inflammation ((full mouth bleeding on probing (Ainamo and Bay 1975)) ≤25% at baseline Exclusion Criteria: * Systemic disease that would interfere with bone or wound healing and dental implant therapy (e.g. uncontrolled diabetes) * Systemic disease that would interfere with bone or wound healing and dental implant therapy (e.g. uncontrolled diabetes) * Any contraindications for general bone grafting and oral surgical procedures * Any anomalies of the sinus that could interfere with planned procedures * History of local irradiation therapy * Local inflammation, including untreated periodontitis * Medical conditions requiring chronic high dose steroid therapy * Treatment with an investigational drug or device within a 30 day period immediately prior to surgery at visit 2, or expected participation in any other investigational drug or device study during the conduct of this trial. * Antibiotic treatment or anti-inflammatory treatment within 4 weeks prior to surgery * History of alcoholism or drug abuse * Immunocompromised subjects * Subjects who smoke \>10 cigarettes per day or tobacco equivalents or chew tobacco * Conditions or circumstances, in the opinion of the investigator, which would prevent completion of study participation or interfere with analysis of study results, such as history of non-compliance or unreliability * Physical or mental disabilities that would interfere with the ability to perform adequate oral hygiene * Current pregnancy (pregnancy test) and breastfeeding women Secondary exclusion criterium: Defects of the Schneider Membrane