The plan is to recruit subjects into 3 groups: 1) systemically healthy, 2) subjects with diabetes (ADA classification determined by glycosylated hemoglobin A1C levels), and 3) subjects with osteoporosis (limited to those on either no drugs or oral bisphosphonates only). All subjects recruited will have already been approved and treatment planned for implant placement by non-study personnel to avoid any potential conflict of interest. All subjects will have mandibular radiographs that show edentulous ridge areas that provide enough alveolar ridge space to place two test cylinders (each approximately 2.9-3 x 5mm) on each side of the mandible. One side will have two titanium test cylinders and the contralateral side will have two trabecular metal test cylinders. After placement of these 4 test cylinders, one will be removed contra laterally from each side at weeks 2 and 4 of healing. Thus, by 28 days all test cylinders will be removed.
It has been our experience that each cylinder after removal will contain enough cells to provide approximately 10-20μg of total RNA. This quantity of total RNA is sufficient to run an Affymetrix chip and have enough mRNA for PCR confirmation. Sampling at 3 days after placement is too soon, as it does not provide adequate mRNA for the analysis, since the clot has not become remodeled or adequately organized to be cellular. Thus, by 1 week organization of the osseous healing will have begun and at week 2 it will be beginning to mature. The week 2 sampling time point) will provide us with early molecular kinetics of the healing response to compare the two metal surfaces and the differences in gene expression that may be associated with diabetes and osteoporosis. At weeks 2 and 4 the test cylinders will be removed using a 5.0 mm diameter tissue punch and a 5 mm trephine drill. Investigators will select 18 random patients (6 subjects per group) to provide (two test cylinders for each, 36 samples) for histology. Investigators will use the trephine drill to remove the 4 week test cylinders in all 3 groups of subjects. In all cases, a subject is eligible for this study by being pretreatment planned to receive a permanent implant bilaterally, which will be placed at donor sites. According to the participant's individual treatment plan, after test cylinders are removed, each site will receive an implant using either a standard 4.1 or 4.7 mm tapered screw vent design implant. The removed test cylinders will be briefly rinsed in saline and prepared chair side for either mRNA extraction or for histology.
