Paul C. Kitchin

The Prevalence of Tooth Root Exposure, and the Relation of the Extent of Such Exposure to the Degree of Abrasion in Different Age Classes

This study is based on 200 individuals examined in the dental clinic at Ohio State University. Most of these were clinic patients, but a small number of dental students and members of the clinic staff were included. The group was divided into 4 age classes as follows: 20-29, 30-39, 40-49 and 50-59. An attempt was made to get a 60-69 year class, but an insufficient number of people with natural teeth were available to permit its inclusion in this report. An equal number of males and females were examined in every age group, thus the 50 individuals making up each of the age classes consisted of 25 males and 25 females. The data were collected by 2 dental graduates working half time each in such a manner as to cover the clinic waiting room at all times. After the data had been collected, a check was made on the number of patients in every age class who had been examined by each observer. This showed a fairly equal division of the work. The 2 observers were checked against each other by having them examine several of the same patients. One observer (B) was consistently more conservative in his grading of the degree of abrasion than was the other (V). However, the fairly equal division of patients between them minimized the personal difference in observation. With this number of patients, however, all data are comparative rather than absolute. The information concerning each patient was gathered on a mimeographed form, a photograph of a sample copy of which is included in

Some Observations on Enamel Development as Shown in the Mandibular Incisor of the White Rat

The study of the development of enamel, especially that part concerned with the actual hardening of the tissue, presents considerable difficulty when attacked by the usual biological methods. Perhaps because of this situation there is a rather general disposition to accept a theory of finished enamel-rod production by the individual ameloblast. However an exception must be credited to Dr. Theodore Beust (1), who, in 1928, voiced a vigorous protest against this theory. Beust studied the intrafollicular condition of the enamel layer in pig material. He observed that only the tips of the cusps of the enamelcap were hard enough to be recognized as enamel, while the remainder was of such a nature that it could be easily removed with the finger nail. This indicated some very essential mass-differentiation in developing enamel. In making celloidin sections of decalcified, unerupted teeth of young pigs, I noted that there was a consistent loss of a part of the enamel layer. Where the tooth was older, the loss was greater. In all the cases observed, the junction between that which remained and that which had been lost was not a tapering off, but an abrupt termination. Figs. 1 and 2 illustrate this condition. The same thing was noted in the enamel layer of sections of decalcified mandibular incisors of rats. Here the enamel tissue in the incisor terminates in an area approximately beneath the first molar. This condition is shown in fig. 3. Mrs. Mellanby (2), in her work on the effect of diet on the teeth of dogs, noted that in ground, stained sections of puppy teeth, secondary

Does Resection of the Nerves Supplying the Mandible Affect Tooth Development

A review of the literature reveals that relatively little attention had been paid to the problem concerning the effect either of traumatic or experimental resection of the nerves supplying the maxilla or mandible on the development or eruption of teeth. Vieyra (4) reported that unilateral extirpation of the superior cervical sympathetic ganglion in dogs operated 7-12 days after birth resulted in retardation in development of the mandibular teeth on the operated side. This author mentions, without citing any references, that Angelucci observed the same effect in dogs, that Nemzoglau on the other hand noted an acceleration in the development of the teeth whereas Hertel observed no alteration in the rate of growth of the teeth in young rabbits. King (3) found (a) that unilateral resection of the inferior alveolar (dental) nerve in young dogs resulted in a slight acceleration in eruption of the permanent teeth on the operated side; (b) that a similar operation on rabbits resulted in acceleration of growth of the permanently growing incisor tooth on the operated side, at least during the first 8-21 days following the operation after which time a slight retardation in rate sometimes occurred and (c) that unilateral extirpation of the superior cervical ganglion in rabbits likewise produced an increased rate of growth of the lower incisor tooth on the operated side. The objective in the present study was to determine whether or not unilateral resection of the nerves supplying the mandible of the kitten affects the development of the permanent tooth-germs. Three series of operations were performed using 2 animals of the same age in each series. In the first series the superior cervical sympathetic

Actinomyces and the Dentobacterial Plaque

HE role of the dentobacterial plaque in the initiation of dental caries has been well established, if not well understood, for over one-half a century. There are many voids in our information pertaining to this minute, mucilaginous mass of microorganisms and salivary debris. These may be the result of a tendency to magnify effect rather than cause. Evidence for such an interpretation is afforded by the numerous methods presented, especially during the past few years, for the control of dental caries. This report presents in part the results of a cultural study of the plaque as a biologic entity. Initially, the attention of the investigation centered upon the plaque as a structure using stained sections prepared without disturbing in situ relationships. Information so obtained directed the effort toward determining the occurrence of Actinomyces and the constancy of these microorganisms in the plaque.

Dens in dente

D ens in dente (dens invaginatus, dilated odontoma, invaginated odontoma, dilated composite odontoma) is a relatively rare dental anomaly which can occur in the crown or root of a tooth.l-s Tomes, in 1859, was the first to describe a case of this condition. The accepted and usual term dens in dente means literally (‘a tooth within a tooth, ” but this has never been reported.4 The condition is, rather, an enamel organ invagination of variable degree, for which reason Oehlers has proposed the more logical and descriptive name, dens invaginatus.3

Effect of Artificially Induced Hyperpyrexia on Tooth Structure of the Rabbit

The increasing therapeutic importance of artificially induced fever raises the question of its effect on developing tooth structure. Damage to the enamel by infections accompanied by high fever during the period of tooth formation has been recognized clinically for many years. It is evidenced as a hypoplastic condition with superficial pits and grooves, often markedly disfiguring the anterior teeth. Detrimental effects in the dentin would be an internal dystrophy and would escape clinical notice but might well be expected under conditions which would affect the enamel. Normal dentin is a homogeneously calcified tissue produced by the dental pulp. It is laid down around the periphery of the pulp in periodic increments as an organic matrix which is subsequently calcified to a bone-like consistency. Unlike bone, dentin once formed is not subject to further physiologic change to any marked degree, and hence it affords a permanent record of any variations in the calcification process. The dentin of the continuously growing teeth of the rabbit, therefore, affords a suitable medium for the recording of any effect which might be caused by artificially induced hyperpyrexia. In the same series of rabbits used for observations on other tissues by the Departments of Medicine and Pathology and reported elsewhere, 1 2 3 histologic studies were made on thin ground sections cut longitudinally through the incisor teeth. Schour and Hoffman, 4 reporting on dentin deposition in growing mammalian teeth, state that it is laid down at the approximate rate of 16 micra in 24 hours. Their work included, among other animals, a series of rabbits. Thus, any periodic interference with calcification would be characterized by the presence in the dentin of alternate layers of normal and abnormal tissue, the latter coinciding with the periods of disturbance.

Effect of Three Diphenylmethane Derivatives on Acid Production in Saliva and on Logarithmic Growth of an Oral Lactobacillus

D IHYDROXYHEXACHLORODIPHENYLMETHANE (G-11) has b e e n shown by Traub, Newhall, and Fuller3 and by Seastone2 to reduce markedly the total flora of the skin for prolonged periods. The duration of the activity was ascribed by Fahlberg, Swan, and Seastonel to retention of the chemical in or on the tissue. This investigation was undertaken to determine if G-11 and two related compounds, dihydroxyquadrochlorodiphenylmethane (XDR-504) and dihydroxydichlorodibromodiphenylmethane (XDR-505), could alter the logarithmic growth of an oral lactobacillus or influence acid production in pooled saliva.

Does the Maxilla Lack a Periosteal Membrane

The periosteum has been a point of contention for almost 200 years, dating from the controversy between Duhamel and Haller (1) concerning its osteogenic or bone-forming power. It is not our purpose to enter into this age old conflict but rather to attempt to clarify the conception which occasionally appears in the literature to the effect that the maxilla lacks, or is poorly provided with, a periosteal covering. Thus, for example, Foman (2) makes the statement that

Dicalcium Phosphate and Codliver Oil as Factors in Prevention of Dentin Hypocalcia Resulting From Artificially Induced Fevers

The therapeutic importance of artificially induced fever, or electropyrexia, in clinical pediatrics raises a question regarding its effect on developing tooth structure. Odontotrophias evidenced as hypoplastic superficial pits and grooves in the enamel have been recognized clinically for many years, and the disfiguration has been interpreted as a result of an eruptive fever. In most instances of enamel hypoplasia there is an accompanying dystrophy of the dentin, which escapes clinical notice since it is not exposed to view. In a series of observations reported previously (1) on the effects of induced hyperpyrexia on the tooth structure of rabbits, it was found that a definite lack of calcification in the dentin was the result, and this effect was evidenced as linear areas of interglobular spaces corresponding chronologically with experimental procedures. Fig. 7 illustrates this condition. The high temperatures were induced by the Kettering hypertherm and by a high frequency short-wave apparatus. Garrison (2), using an incubator and making his observations on albino rats and Bevelander (3), using a type of short wave apparatus and also making his observations on albino rats, were both in accord with the conclusions drawn from our studies on the rabbit series. Further studies with the same short-wave equipment used in treating the rabbits, were made by us with albino rats with similar results. The radiotherm, or high frequency machine, utilized in these investigations produces wave-lengths of 25 meters at 12,000,000 oscillations per second and its radio frequency can be varied from 0.02 to 0.4 amperes,

Observations on Peripheral Nerves Following Local Injections of (1) Isotonic Solutions of Varying ph aNd (2) "Iso-pH" Solutions of Varying Tonicity

The value of investigative work in the field of materials used in the practise of dentistry is amply demonstrated by the effort on the part of manufacturers to pattern their products along the lines indicated by the results of such research. In recent years considerable work has been done on local anesthetic agents. Much of the investigative work has concerned itself with the speed of anesthetic action as affected by the pH and the osmotic pressure values of the solution. We have, however, been unable to find any reports which are concerned with the morphological reactions of the tissues, in close proximity to the injection, to varying degrees of pH and osmotic pressure values of the injected solution. From the physiological viewpoint it would seem reasonable to require that solutions injected into patients should have pH and osmotic pressure values identical to those of the body tissues. However, it would be more logical if the actual range over which these factors could be tolerated were determined. The purpose of this investigation is to study the morphologic reaction of peripheral nerve trunks following local injections of solutions of varying pH and osmotic pressure values. It is hoped that this experiment will indicate the tolerance of the tissues to these factors. If, by this investigation, the range of tolerance to pH and osmotic pressure values can be delimited, it would seem plausible, on purely theoretical grounds, that solutions outside these tolerances may be in