Joseph P. Weinmann

Correlation of Chemical and Histological Investigations on Developing Enamel

The aim of the present investigation is to analyze the main chemical components of developing enamel and to correlate the chemical findings with the corresponding histological appearance. Such investigations are entirely lacking. All previous information on the chemistry of calcification of the enamel is based on indirect evidence. Historically, the first method for determining the changes taking place in the developing enamel was the use of the polarizing microscope (Valentin, Hoppe, von Ebner, W. J. Schmidt, Kitchin). The majority of investigators have drawn conclusions concerning the nature of developing enamel from the staining reaction of decalcified and ground sections (Beust, Mellanby, Kitchin, Chase, Diamond and Weinmann). Applebaum (1) correlated his observations made with the Grenz ray to the findings of previous investigators. In the present study on pig tooth germs an attempt is made to define the 2 distinctly separated stages of enamel development, i.e., enamel matrix formation and calcification (8), in terms of chemical values.

The Keratinization of the Human Oral Mucosa

Earlier observations (1, 2) indicated the necessity for cytologic studies of the cellular elements in the saliva. The following report deals with the process of keratinization of the epithelial cells and with the degree of keratinization on different areas of the mucous membrane of the human mouth. Smears were made from different areas of the mouth and stained without fixation. This method permitted the observation of each cell separately. This is the first time this method has been used for cytologic investigations of oral mucous membrane, insofar as the author has been able to determine.

Age Changes in the Periodontal Tissues of the Rat Molar

THE physiologic aging process of the periodontal tissues has been a subject of considerable interest to the dental profession as a whole, and to the periodontist in particular. A knowledge of the physiologic changes of the periodontal tissues with age is essential to an understanding of periodontal diseases. The purpose of this study was to follow in the rat molar the changes that occur from youth to old age in the position of the epithelial attachment, the incidence and degree of gingival inflammation, the position of the alveolar crest, the state of cellular activity at the alveolar crest, the width of the interdental septum, the position of the cellular cementum, and the amount of root resorption. The rat molar, which is a tooth of limited growth, provides a fair comparison with the permanent human tooth, and has been used for that reason in experimental studies. An attempt also was made to establish basic information which would be essential to evaluate the results of experimental studies in the molars of rats of different ages.

Experimental Production of Sarcomas by Methyl Methacrylate Implants.

Summary Subcutaneous implantation of methyl methacrylate film in mice resulted in a 25% incidence of fibrosarcomas. The incidence of fibrosarcomas was 14.3% with cellophane implants.

The Prevalence, Distribution, and Morphologic Changes of the Epithelial Remnants in the Molar Region of the Rat

T HE PURPOSE of this study is to classify the different forms of epithelial remnants and to investigate the prevalence and incidence of these structures in the periodontal membrane of the molars of the rat. This study is an attempt to provide a base line for later investigations on the fate of the epithelial remnants of the rat molars under different systemic conditions and to serve as a part of a broader study of the biology of epithelium.

Tumors of the minor salivary glands: A study of twenty-three cases

Abstract One hundred eighty-one previously reported cases of minor salivary gland tumors have been reviewed, and twenty-three additional cases of these tumors have been described. These new cases fell into the following groups: pleomorphic adenomas (4), canalicular adenomas (4), myoepitheliomas (3), mucocyst adenoma (1), fibroadenomas (3), mucoepidermoid tumors (6), and adenocarcinomas (2). Various special stains were used to demonstrate the cellular elements of these tumors. Mucicarmine stain demonstrated that the so-called “pseudocartilage” of the pleomorphic adenomas is a result of admixture of mucin and stromal materials into which the parenchymal cells are incorporated. Relatively rare canalicular adenomas and myoepitheliomas are described. These tumors consist almost exclusively of ductal cells and myoepithelium, respectively. A benign tumor of unusual morphology is described for the first time. It consisted of sheets of an eosinophilic polygonal cell with interspersed pools of mucin. This neoplasm was termed mucocystadenoma . Since, from the microscopic picture alone, the innocence or the malignancy of mucoepidermoid tumors cannot be established, these tumors were not subdivided into the malignant and benign varieties. It is suggested that all mucoepidermoid tumors be considered malignant or potentially malignant. The most common site of origin of the tumors of minor salivary glands was found to be the palate, and the most common neoplasm was the mucoepidermoid tumor. This is in contrast to the tumors of the major salivary glands, the majority of which are pleomorphic adenomas of the parotid gland. Because of their size and location, most of the reported tumors of the minor salivary glands were clinically misdiagnosed as mucoceles or fibromas.

The Influence of Injury to the Periodontal Membrane on the Spread of Gingival Inflammation

IN A previous report, the early histologic changes in the supporting tissues of rat molars during experimental tooth movement have been described (Macapanpan, 1952). Tooth movement had been induced by the insertion of a piece of rubber dam between the upper first and second molars. This rubber dam acted not only as a separator but also as a foreign body. Its insertion led to severe papillary gingivitis that later spread into the adjacent tissues. The result of this experimental procedure thus was twofold: by local injury, it produced a gingivitis, and by a movement of the tooth exceeding physiologic limits, it produced a simultaneous damage to the periodontal membrane. It was, therefore, thought worth while to analyze the spread of a gingival inflammation in instances of coexisting trauma to the periodontal membrane.

Effects of Filling Materials on the Pulp of the Rat Incisor

THIS investigation was designed to study the effects of a variety of commonly used filling materials upon the growing dentin and the pulp of the incisor of the albino rat. One of the important requirements of a dental filling material is that it does not harm the pulp. Investigators and clinicians have, therefore, stressed the need for a rapid and simple method of testing the effects of filling materials on the living pulp before these are used in human teeth. While histologic analysis of the effects of filling materials on the pulp in human teeth is essential to accuracy and objectivity, patients are reluctant to sacrifice teeth for experimental purposes. On the other hand, animal experiments permit the accumulation of relatively large numbers of specimens within a relatively short time. Most important, the conditions of testing can be more accurately controlled. The experiments can then be replicated until the variables are determined and the effects of each material on the pulp can be assessed in an objective and quantitative manner. Until very recently, the dog was the experimental animal of choice, with occasional studies in monkey and man. In 1952, one of us (I. S.) suggested the use of the rat incisor and molar for the analysis of the effects of filling materials on the young and adult pulp. One of the objectives of this study was to establish the validity of using the rat incisor for the bio-assay of new filling materials introduced to operative dentistry.

A MODIFICATION OF GOMORI'S METHOD FOR DEMONSTRATION OF PHOSPHAMIDASE IN TISSUE SECTIONS

The shortcomings of Gomoris method for the histochemical demonstration of the enzyme phosphamidase lie in the need for a long incubation period and for the distinction between reaction products due to enzyme action and those due to spontaneous hydrolysis of the substrate. A modification of his method is suggested which permits reduction of the incubation period to about a fourth and eliminates the need to distinguish between reaction products of different origin in brief incubations. The suggested procedure is free from erratic failures to obtain positive results. As tested for brain, the overall pictures of enzyme distribution are uniformly reproducible. Variability of results is reduced to the occasional occurrence of small areas in which no precipitate has formed. It is felt that with these changes the method is ready to be subjected to a more advanced stage of investigation, as for instance the preservation of the enzyme content during fixing, dry-freezing, etc.

PHOSPHAMIDASE CONTENT OF NORMAL AND PATHOLOGIC TISSUES OF THE ORAL CAVITY

The phosphamidase content in normal and pathologic tissues of 37 biopsies from the oral cavity was examined using the histochemical method of Gomori. High concentrations of phosphamidase were found in the epithelia of epidermoid carcinoma, leukoplakia, papilloma, pleomorphic salivary gland tumor, in the proliferating connective tissue of a giant cell tumor and in the epithelium adjacent to a fibroma and in the epithelium of blastomycosis. Low concentrations of phosphamidase were found in a few cases of inflammation of the mucous membrane associated with hyperkeratosis. The phosphamidase reaction was negative for normal epithelium and connective tissue of the oral mucous membrane, the lining of the maxillary sinus and mucous glands. The present limitations of the technique are discussed and some precautions against erroneous conclusions presented.