Human histologic evaluation of HTR polymer and freeze-dried bone allograft. A case report

This case report compares the results of placement of HTR (Hard Tissue Replacement Synthetic Bone) and freeze-dried bone allograft (FDBA) in the same patient. 2 notches were made in each of 6 teeth, 1 at the gingival margin and the other at the most apical level of calculus. Soft tissue responses with both materials included probing depth reduction, gingival shrinkage and gain in clinical attachment. Histological sections of block extraction sites 30 months after placement of either material showed no signs of new attachment. Little or no inflammation was present with both materials. There was also an absence of all FDBA particles which assumes complete resorption of this material prior to 30 months. Gingival shrinkage resulted in the exposure of the gingival and calculus notch in all FDBA treated sites. Gingival epithelium was found adjacent to the gingival notch in all HTR treated sites. The calculus notch in HTR treated sites was lined by junctional epithelium with connective tissue and bone opposing the adhesion. HTR particles were present and surrounded by connective tissue or bone. HTR appears to serve as a scaffold for new bone formation when in close contact with alveolar bone.