The distribution and structure of the new bone emerging in the early stage after the bone graft was investigated. Fresh autogenous bones were placed in the dog mandible and light microscopic observations on the serial sections of the specimens 2 weeks after the grafting were carried out.
The new bones have been collectively called immature bones, nonlamellar bones or woven ones. The author classified these into type I, type II, and type III by the structural charactber.
The type I is the less differantiated bone tissue among the 3 types, which has no lamellar structure. The type II is composed of the center part and peripheral part. The center part is a core which consists of type I bone. In the peripheral part, there are fine matrix fibers oriented in parallel with the surface of type II, but there isn't any apparent lamellar structure. The type III has a high stainability to eosin and it's lamellar structure is clear.
Ordinarily, according to the distance from the inflammatory focus, there exist in order the type I, the type II and the type III, after bone grafting and the bone formation happens in the same order. It was found that when the inflammation remains or the dense fibrous tissue is formed after the grafting, this process is delayed.