Ridge Augmentation: Particulate v/s Block Graft

Alveolar Bone Loss

The primary aims of this study are to compare the clinical and histologic results of bone regeneration with a cancellous block allograft versus MinerOss Cortico cancellous particulate allograft mixed with autogenous bone chips after 4 months of healing. Titanium reinforced hd-PTFE (Cytoplast) membrane GBR will be used to cover the bone grafts. Specific Aim 1: To compare the baseline to 4 month change in clinical ridge width and height. Specific Aim 2: To compare the histologic percent of vital and nonvital bone and trabecular space at 4 months. The primary outcome variable is the change in horizontal ridge width. The secondary outcomes are the change in ridge height and the percent histologic composition of the augmented site.

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.

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