Samuel W. Chase

A COMPARATIVE STUDY OF THE HEALING PROCESS FOLLOWING DIFFERENT TYPES OF BONE TRANSPLANTATION.

A controlled comparative study was made of the osteogenic properties of various types of bone grafts in dogs. A rating scale was applied to the histological criteria used for the evaluation of the grafts, and a tabular and statistical evaluation of the results was carried out. Fresh autogenous bone was clearly superior; freezedried homogenous bone was the next highest in rating. The rest of the grafts tested rated in the following order: frozen homogenous, decalcified homogenous, frozen irradiated homogenous, freeze-dried irradiated homogenous, fresh homogenous, deproteinized heterogenous, and deproteinized homogenous. An indication of the approximate level of significance of this ranking was given. The deficiencies in the data related to the great variability in the response of the animals and the small numbers of animals at each test interval are discussed.

EXPERIMENTAL STUDIES IN THE TRANSPLANTATION OF WHOLE JOINTS

Some of the cells in autogenous whole joints remain viable following transplantation. The bone is rapidly revascularized and the dead bone is replaced with new bone. The deeper layers of cartilage cells remain viable, but some degeneration of the articular surface usually results. All of the cells in delayed homogenous transplants and most of the cells in direct homogenous whole-joint transplants die. Revascularization and active osteogenesis are slow. The grafts unite and function satisfactorily for six to eight months, but degenerative changes similar to those seen in aseptic necrosis begin between four and six months after transplantation. These changes may progress to complete disintegration of the joint. Since similar changes occur in direct homogenous transplants as in delayed homogenous transplants, the method of preservation apparently is not the important factor in the early degenerative changes. The factor that produces these degenerative changes, which are so much greater than those in autogenous whole-joint transplants, has not been determined but is probably related to a type-specific physicochemical structure of bone. The writer has had no experience in using whole-joint transfers clinically, but from the experimental data at hand he believes that one could expect satisfactory results from autogenous transfers, particularly in non-weight-bearing joints, such as the small joints of the hand. Homogenous joint transplants, direct or delayed, heal satisfactorily, unite to the host bone, and are technically feasible. Possibly in non-weight-bearing joints, with good cooperation by the patient, satisfactory clinical results might be obtained. In most instances, however, and particularly in weight-bearing joints, long-term good results are not to be expected at present. It is hoped that further investigative work will reveal methods of accurately matching bone types and thus make such massive homogenous transfers as entire joints acceptable.

Osteogenic Induction by Osteosarcoma and Normal Bone in Mice

1. Osteogenic induction across a Millipore filter barrier by normal mouse calvarias and mouse osteosarcoma was demonstrated in mice. 2. The amount of external bone induction was considerably greater with two-week and eight-week-old mouse calvarias than with newborn calvarias, but the incidence of bone induction dropped sharply with eight-week calvarias. 3. The amount of external bone induction by the mouse osteosarcoma was from fifteen to seventy-five times greater than that by the normal bone. 4. External induction did not occur with any chamber in which bone was not growing or with any chamber containing rat calvaria or human osteosarcoma.

A Critical Evaluation of Processed Calf Bone

The commercial availability of processed bovine boric has provided the surgeoni with a convenient, readily available, arid almost unlimited supply of boric-graft material. In addition to these obvious advantages, data have been published itt support of claims that processed bovine bone is well tolerated by the host, manifests negligible antigeniicity of the immediate type, arid undergoes remodeling as rapi(lly as autogenous bone i,2,3,4,5.6,s,I2,i3 From these data arid an extended clinical trial it has been concluded by its proponents that the quality of processed calf boric as a graft material “compares favorably to that of human autogenous bone grafts” . The experimental models in which this material has been tested have been al most exclusively designed as window defects in either cortical or cancellous boric. Under these conditions practically all grafting materials will be incorporated anicl the defect obliterated. Indeed, data from our own studies indicate that, given a vascular defect surrounded by boric, an empty hole will be filled with woven boric more rapidly than one containing a plug of fresh autogenous cancellous borne. Iii fact, this same observation was made iii one of the studies on processed calf bone . Data drawn from experiments of this design indicate principally the degree to which a material may be inicorl)orated arid remodeled in the normal healing process. They tell us very little about the ability of a graft to initiate arid support osteogeniesis under circunistan(’es in which osteogeniesis in the host bed is less active. In general, siicli studies will tend to minimize differences between bone-grafting materials rather t han t o emphasi ze them. Any stage of the healing Pr (’css iii boric is always the sum of the contributions from both the transplanted material and the recipient site. If we wish to see (‘learly the contribution of the graft material, then the contribution of the recipient site must he reduced to where it is unIv a fraction of that of the graft. However, non-osseous, minimally reactive, soft-tissue sites are riot satisfactory either because they will riot allow us to evaluate the stiniulatinig effect of a graft upon an indolent osteogeriic bed. In a previous stud ’ three of us (K.G.H., S.W.C., arid C.H.H.) assessed the healinig process in eight types of boric grafts compared with aut.ogenious controls. An experimental niodel vas used which we believe nieets most of the criteria indicated above. Briefly, it consists of creating a standard segmental defect iii the nIna t\Vice as long as the dianieter of the diaphysis. This will result in non-union in most instances if the defect does riot receive a graft., arid iii some cases riot even fresh autogenous cancellous boric will heal the defect. The purpose of the present stud ’ ‘as to evaluate processed heterogenious calf bone in our standardized test system. By using the identical system anid time * Read at the Annual Meeting of The American Academy of Orthopaedic Surgeons, San Francisco, California, January 18, 1967. t This investigation was supported iii part by Public lTealth Service Grants, Nos. Ti AM 5437 and AM 06075 from the National Institute of Arthritis arid i\Iet.aholic Diseases arid the Rainbow hospital Research Fund. 2065 Adelbert Iload, Cleveland, Ohio 44106.

Effects of diets containing fluorine on jaws and teeth of swine and rats.

For five years investigations of effects on animals of diets containing fluorine (F), especially diets containing rock phosphate as a mineral supplement, have been in progress at the Ohio Agricultural Experiment Station. During these experiments, the first two collaborators accumulated much material. They invited the last two collaborators to investigate this material with regard to effects on teeth and jaws. This report presents the results of this investigation.

The Development, Histology, and Physiology of Enamel and Dentin-Their Significance to the Caries Process

My remarks are going to be concerned chiefly with those structural features of the dentin and enamel which seem to me to be most pertinent to the mechanism of caries. Since the enamel is the first line of defense against caries, it will be given more attention than the dentin. I do not need to go into an extensive account of the development of these tissues, yet I consider it necessary to say a few words about their development in order that we may, perhaps, better understand their adult structure. The dentin begins to form at the surface of the dental papilla after the formation of a superficial layer of cells, the odontoblasts, which are close relatives of osteoblasts, or bone-forming cells. The dentin forms in much the same fashion as bone, a fact which was emphasized many years ago by von Korff,27 whose name has been given to both the osteogenic and the dentinogenic fibers. The undifferentiated odontoblasts are closely comparable with, and perhaps derived from, the ordinary fibroblasts found in the dental papilla and later in the dental pulp. When dentin begins to form they change their shape, their cytoplasm undergoes alterations, and these cells, probably solely fibroblastic at first, become certainly more closely related to the process of dentinogenesis that some recent claims indicate. For example, Gottlieb21 has stated that the only function of the odontoblasts is to keep the dentinal tubules open. This claim, in my opinion, is not justified, since there is good evidence of active participation in dentinogenesis. Bevelander and Johnson2 have shown that the odontoblasts become loaded with alkaline phosphatase just prior to and during early calcification of the dentin which indicates that they are in some way concerned with the precipitation of mineral salts. Also we have reason to believe that they are intimately associated with the formation of the fibrillar portion of the dentinal matrix. Orban34 demonstrated excellently the relation of the collagenous fibrils of predentin to the Korffs fibers and other precollagenous fibers of the pulp, and Sicher36 has recently presented convincing arguments associating the odontoblasts with the production of Korffs fibers. Sichers paper is a sane, succinct and sound account. As each layer of predentin is calcified the dentinal matrix is built up layer by layer, each odontoblast contributing a much branched, constantly elongating odontoblastic process lying in a similarly branched dentinal tubule. The cellbody of the odontoblast remains outside the dentin on the surface of the dental pulp.

Some Uses for Dissolved Celluloid in the Preparation of Ground Sections of Bones and Teeth

I. Dissolved celluloid as an adhesive during the process of grinding and polishing. 251 II. Dissolved celluloid as an advantageous substitute for balsam in the Koch petrifaction method....................................................... 252 III. Dissolved celluloid as a substitute for celloidin in the White method.... 254 IV. Literature cted ...... .................................................. 254