Histological Comparison of Ridge Preservation Using Mineralized FDBA Alone Versus a Combined Mineralized-Demineralized Freeze Dried Bone Allograft

This entire protocol involves procedures that are standard care. The purpose of the research is to evaluate whether there are any differences in new bone formation following tooth extraction and grafting of the extraction socket with either 100% mineralized FDBA (FDBA) or a combination of 70% mineralized & 30% demineralized FDBA (DFDBA). Both FDBA and DFDBA are commonly used in dentistry for this purpose. Until recently, there has been no human evidence of differences in new bone formation with one material versus another. Recently, DFDBA has been shown to provide a greater percentage of vital bone formation than FDBA. No studies have been done on materials that provide a combination of demineralized and mineralized FDBA for ridge preservation. That is the purpose of this study.

There will be two subject groups in this study. All subjects will require extraction of at least one non-molar tooth, followed by replacement of the missing teeth with dental implants. Each group will have 22 subjects. The primary distinction between groups will be the use of either a combination of 70% mineralized & 30% demineralized FDBA or 100% mineralized FDBA: Group 1 will have 70% mineralized & 30% demineralized FDBA grafted into the extraction socket for ridge preservation. Group 2 will have 100% mineralized FDBA grafted into the extraction socket for ridge preservation. The allocation of subjects into group 1 or 2 will based on numbers drawn from a stack of sealed envelopes. A small flap will be reflected to an extent about 3-4mm beyond the bony walls of the socket. A measuring stent will be placed and measurements of ridge width and ridge height will be taken and recorded to the nearest 0.5mm. Ridge width will be measured using a ridge caliper at a point approximately 4mm apical to the facial and lingual bony crest. Ridge height will also be measured. The tooth will be extracted and the subject will then be randomized by drawing a sealed envelope from the stack. Either 100% mineralized FDBA or a combination of 70% mineralized & 30% demineralized FDBA will be placed in the socket to restore the ridge to appropriate contour. A dense polytetrafluoroethylene (PTFE) membrane will then be placed over the socket orifice extending about 3mm beyond the bony socket walls. A PTFE suture will be placed over the membrane to secure it in place. Primary closure will not be attempted. The patient will be seen 7-10 days after extraction/ridge preservation to assess healing. The subject will be seen again 21-28 days to remove the PTFE membrane and to assess clinical healing.

At the time of implant placement, the measuring stent and caliper will be used to determine the ridge width and ridge height again. The implant site will be prepared using a hollow trephine which allows retention of the bony core. The bone removed from the osteotomy site remaining in the trephine will be prepared for histologic examination and analyzed for new bone growth. The following histologic parameters will be measured: percent vital bone formation; percent residual graft material; and, percent nonmineralized connective tissue/bone marrow. Following initial preparation of the implant site with the trephine, an implant of the appropriate length and diameter will be placed. A healing abutment will then be placed. All subjects will be examined at 7-10 days following implant placement. The study will end at the time of this follow up visit. The patient will then be referred to his/her restorative dentist for final restoration.