Human Stem Cells and Tissue Responses to Xenogeneic Bone Block: An In Vitro and Histologic Study

Premature loss of a tooth element causes extensive local bone atrophy. Block biomaterials are used in patients with an atrophic maxilla to reshape the premaxilla bone. This study aimed to evaluate the responses to xenogeneic bone blocks at cellular and tissue levels.

Viability of human periodontal ligament stem cells (hPDLSCs) submitted to culture medium-containing substances leached from a xenogeneic block biomaterial (Orthogen) was assessed by the MTT assay. Cells grown in a fresh medium were used as the control. Cell viability was measured at 24, 48, and 72 hours. The results were statistically compared (α ≤ .05). Tissue response to the biomaterial was evaluated by the placement of xenogeneic blocks anchored with miniscrews in six patients with atrophic maxillae and a remaining cortical bone tissue thickness of 2.0 to 3.0 mm. After 8 months, specimens were collected from the grafted areas and analyzed under a light microscope for evaluating the types of collagen fibers and amount of newly formed bone tissue, using the Image-Pro Plus software program.

The number of viable cells was similar in both groups. The histologic sections revealed remaining biomaterial in 10.12% of the patients and newly formed bone in 21.57%.

The xenogeneic block biomaterial tested proved to be biocompatible in vitro, and the porosity of the block favored the in vivo formation of new bone matrix deposits.