Approximately 60 subjects who require at least one posterior maxilla implant in the areas of the second pre-molars or (first or second) molars with 6 to 9 mm of crestal bone below the sinus floor, as determined on the computerized axial tomographic (CT) scan, will be recruited for the study. Subjects will receive dental implants to replace a missing tooth (second pre-molar or first/second molar) on one side of the maxillary arch. Each subject will receive one type of implant: platform switched (PS) or platform matching (PM). Each site will receive either a bone graft material composed of anorganic bovine bone mineralized (ABBM, Bio-Oss, Geistlich Pharma) or no graft material (collagen membrane used for wound healing (Collatape, Zimmer)). At implant placement surgery and post-surgical follow-ups, the treated site will be examined, clinically measured, and radiographs and photographs will be taken.