Deproteinized bovine bone (Bio-Oss) and bioactive glass (Biogran) arrest bone formation when used as an adjunct to guided tissue regeneration (GTR): an experimental study in the rat.

Objectives: Grafting of deproteinized bovine bone or bioactive glass has been suggested as an adjunct to guided tissue regeneration (GTR) for the treatment of periodontal and peri-implant bone defects but the influence of these materials on bone formation is not clarified. The aim of the study was to examine the long-term influence of deproteinized bovine bone (Bio-Oss) or bioactive glass (Biogran) on bone formation produced by GTR.

Material And Methods: Eighteen rats were used. Following incisions along the inferior border of the mandible, muscle-periosteal flaps were raised to expose the mandibular ramus. Rigid, hemispherical, Teflon capsules (6 mm internal diameter and 1 mm peripheral collar) loosely packed with a standardized quantity of either deproteinized bovine bone (test group 1) or bioactive glass (test group 2), or empty capsules (control group) were then placed with their open part facing the lateral surface of the ramus (one capsule per animal). After 1 year, the capsules were removed by a reentry operation, and the animals were sacrificed. Histological specimens of the augmented sites were prepared, and the volumes of (1). newly formed bone, (2). graft particles, and (3). soft connective tissue in the space originally created by the capsule were estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling.

Results: Limited bone formation was observed in the two test groups. The major part of the space originally created by the capsules was occupied by graft particles embedded in connective tissue. The mean volume of newly formed bone occupied only 23% of the total space in the animals grafted with Bio-Oss and 12.6% in those grafted with Biogran. In the control animals, however, 88.2% (p<0.01) of the space was filled with newly formed bone. There were no signs of ongoing bone formation in any of the three experimental groups.

Conclusion: It is concluded that grafting of Bio-Oss or Biogran as an adjunct to GTR arrests bone formation.