Fate of bone formed by guided tissue regeneration with or without grafting of Bio-Oss or Biogran. An experimental study in the rat.

OBJECTIVES

The aim of the study was to examine whether bone produced by guided tissue regeneration (GTR) in combination with Bio-Oss or Biogran is stable on a long-term basis.

MATERIAL AND METHODS

Fifty-four, 3-month-old Wistar rats were divided into three groups and rigid, hemispherical, teflon capsules were placed with their open part facing the lateral surface of the exposed mandibular ramus (one capsule per animal). In the first group, the capsules were loosely packed with a standardized quantity of Bio-Oss, in the second group with Biogran, and in the last group were left empty. After 1 year of healing, the capsules were removed. Six animals from each of the 3 experimental groups were killed immediately after capsule removal (baseline), or 3 or 6 months after re-entry. The volume of (1) newly formed bone, (2) remaining biomaterial particles, and (3) soft connective tissue in the space originally created by the capsule was estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling.

RESULTS

While considerable bone formation had occurred in the empty control capsules, only limited bone formation was observed in the two test groups. The major portion of the space originally created by the capsules in the test groups was occupied by biomaterial particles embedded in connective tissue. At baseline, the mean volume of newly formed bone occupied 23% of the original capsule space in the animals grafted with Bio-Oss, 12.6% in those implanted with Biogran, and 94.1% in those that received empty control capsules. Six months after capsule removal, the corresponding values were 21.5%, 13.2%, and 91.7%, respectively. No statistically significant differences were observed between baseline, and the 3-, and 6-month observation times in terms of bone volume for any of the three treatment groups (p>0.05).

CONCLUSION

Bone produced by GTR with and without implantation of Bio-Oss, or Biogran, is stable on a long-term basis, but bone formation is obstructed by implantation of these biomaterials.