Ridge Augmentation Comparing the Clinical and Histologic Healing of a Cancellous Block Allograft Versus Corticocancellous Particulate Allograft Mixed With Autogenous Bone Chips

30 patients will be treated using the principles of guided bone regeneration and ridge augmentation. 15 test patients will receive a corticocancellous particulate allograft mixed with autogenous bone chips. The positive control group of 15 patients will receive a cancellous block allograft. Both the groups will receive a hd-PTFE (Cytoplast) barrier membrane. An allograft can be defined as bone that can be obtained from a different individual of the same species (human donor bone) whereas a autograft can be defined as bone that can be obtained from the same individual. Following flap reflection, vertical measurements will be done using a acrylic occlusal stent and horizontal measurements will be done using a specially designed caliper. Approximately 4 months post surgery, a trephine core will be taken from the grafted site immediately prior to the implant placement and submitted for histologic processing. The last step in the study will be to obtain a trephine core (2.7 X 6mm). After the core is harvested a dental implant will be placed. Implant placement should be considered a post study treatment procedure. There is no intent to investigate implant placement outcome. Step serial sections will be taken from each longitudinally sectioned core. The sections will be stained with hematoxylin and eosin. Ten slides per patient will be prepared with at least 4 sections per slide. For each patient 6 of 10 slides will be assessed. The mean percentages of vital and non vital bone and trabecular space will be determined for each patient by using an American Optical Microscope at 150X with a 10 X10 ocular grid. Histologic preparation will result in destruction of the trephine cores. Means and standard deviations will be calculated for all parameters. A paired t-test will be used to evaluate the statistical significance of the differences between initial and final data. An unpaired t-test will be used to evaluate statistical differences between the test and control groups.