Study to Evaluate Implant Survival Rate of Astra Tech Fixture ST in the Posterior Maxilla With One-stage Surgery and Early Loading

Inclusion Criteria: * Age 18 - 75 * Unilateral or bilateral edentulism in the posterior maxilla, last tooth should be the canine or the first bicuspid * Willing to give informed consent Exclusion Criteria: * Bone height \< 5 mm, in the planned implant area * Bone width \< 5 mm, in the planned implant area * Previous bone augmentation procedure in the planned implant area * Previous failures of endosseous implants * Untreated caries and/or periodontal disease of residual dentition * History or presence of any systemic or local disease or condition that would compromise post-operative healing and/or osseointegration * Systemic corticosteroids or any other medication that would compromise post-operative healing and/or osseointegration * Current alcohol or drug abuse * Unable or unwilling to return for follow-up visits for 3 years