Role of periosteum in the formation of jaw bone. An experiment in the rat.

The aim of the present investigation was to evaluate the bone-forming capacity of the outer (fibrous) and inner (cambium) layer of the mandibular periosteum in skeletally mature rats. The experiment was carried out in 25 rats. The mandibular ramus was exposed on one side (experimental side) after elevation of a muscle-periosteal flap. A teflon capsule was placed with its opening facing the periosteum at the subsurface of the raised muscle-periosteal flap after suturing. In the contralateral side serving as control, the periosteum of the lateral aspect of the mandibular ramus was left intact. This time the teflon capsule was placed with its opening facing the periosteum left behind at the ramus. The histological analysis demonstrated that in all experimental and control specimens, some bone was produced at 7 days after operation. In the experimental specimens, however, both the incidence and the amount of newly-formed bone in the teflon capsules gradually decreased from 7 to 120 days, while increasing in the control capsules placed over the periosteum. At 120 days, the mean amount of new bone produced in the experimental capsules was 3% (range 0-15%) of the total space created by the capsule, while it was 68% (range 41-85%) for the control capsules. The results demonstrated that substantial amounts of bone can be produced predictably by the placement of an occlusive teflon capsule facing mandibular covered with periosteum. Bone produced from the periosteum and without continuity with existing bone becomes resorbed with time.