Formation of jawbone tuberosities by guided tissue regeneration. An experimental study in the rat.

The aim of this study was to explore the possibility of creating bone tuberosities on the mandibular ramus in rats, using a rigid, occlusive, Teflon capsule. The experiment was carried out in 30 rats. The mandibular ramus was exposed bilaterally. On the test side, the periosteum was left covering the lateral surface of the ramus. On the contralateral side (control), the periosteum was elevated from the lateral surface together with the flap. A hemispherical, Teflon capsule was then placed to face the periosteum or the bone surface with its open part before closure of the wound. The healing periods comprised 7-120 days. Histological analysis demonstrated increasing bone fill in the test specimens from 7 to 60 days, and a limited further increase was observed from 60 to 120 days. In the control specimens, limited bone fill was seen within the first month after surgery, but substantial amounts of new bone were produced from 30-120 days. At 120 days, the mean amount of bone obtained in the test specimens was 56% (range 39%-71%) of the total space created by the capsules, and it was 52% (range 32%-85%) in the controls. The amount of newly formed bone was equivalent to a 5-6 times increase of the original width of the mandibular ramus. These findings indicate that a secluded space created by an occlusive barrier adjacent to existing bone or periosteum may be filled out with bone tissue. This may have a great clinical impact in cranial and maxillofacial surgery.