Hermann Becks

Human saliva XIII. Rate of flow of resting saliva of healthy individuals

The necessity of determining the normal variation of salivary rate of secretion among healthy individuals, and thereby establishing a cross-section of the population, has been stressed repeatedly (6, 7, 25, 19) because of the known effects of changes of rate of flow on most salivary constituents. Few reports only are available on a sufficiently large number of observations which would permit the biometrical evaluation of these relationships. The lack of attention to the fact that human saliva is a secretory and/or excretory product is reflected in the exclusive use of mg. % values, a measure of concentration, rather than of mg./hr. values, i.e., a measure of total secretion per time unit (9). Furthermore it has been intimated that decreased salivary rate of flow may be related to the dental caries process, while increased secretion may have a beneficial effect on the teeth and oral mucosa (20, 21, 22, 23, 24, 28, 31, 34, 39). The great variations in speed of salivary secretion met by every investigator has made it very desirable to establish averages of rates of salivary flow in human beings of all age groups under standard conditions.

Orthodontic prognosis: Evaluation of routine dentomedical examinations to determine “good and poor risks”

I T IS generally conceived that the success of orthodontic therapy depends not only on the digital skill of the operator but also on a thorough knowledge of the mechanical principles of treatment and of the biologic laws which form a common basis of dental and medical practice. A failure to recognize and apply some of these fundamentals may lead to undesired results and render the prognosis unfavorable. To complicate the problem further it must be admitted that the etiology of a large number of tissue changes in the paradentium is only partially understood. Probably for this reason it happened that a prominent member of your profession stated more than ten years ago that the results in a certain percentage of his cases were not as favorable as desired because the patients had been originally, as he termed it, “poor risks.” This alibi may be perfectly legitimate ; however, it should be remembered that cases may still be risky even if they are “good risks.” If we consider the definition of the word “risk,” we realize that it means a chance of encountering harm or peril ; it means hazard or danger, as in “the risk of drowning. “i In relation to orthodontic therapy or prognosis the word “risk” implies that we are uncertain, to say the least, as to the efficacy of many therapeutic methods and the use of this term by orthodontists is an admission that certain fundamentals are not yet understood. Many obscure factors (frequently of a biologic nature) may interfere with local therapy‘s0 that the effects of mechanical appliances are not those that were planned and desired. During the past few decades, orthodontic science has progressed largely through improvement of mechanical appliances for the correction of dentofacial anomalies. Little progress has been made in discovering etiological factors responsible for early malposition of teeth or biologic factors affecting the tissue unfavorably during orthodontic movement of the teeth. When I appeared before your society three years ago in New York, I reported4 that a large percentage of orthodontic patients who had marked root resorptions were found to have coexistent systemic disturbances. In another group of patients who also had root resorptions but never received orthodontic treatment because of a favorable occlusal relationship, about the same frequency of systemic disturbances was found. Emphasis was placed on the fact

The development of the dentition of Macaca mulatta: Its difference from the human pattern☆☆☆

A metric and roentgenographic study was made on the development of the dentition of 41 specimens and 6 skulls of Rhesus macaques. They covered four consecutive developmental periods. An outstanding finding consisted in the uniformity of the morphogenetic pattern of all the specimens of each period studied. The ontogenetic pattern of the Macaca dentition then was compared with that of man in order to gain some information about the direction of certain evolutionary trends in human phylogeny. 1. 1. In the deciduous dentition of Macaca all the teeth were in proximal contact with the exception of the canines. “Ape spaces” existed mesially and distally to the lower canines and mesially to the upper canines. This arrangement can be found in man among deciduous dentitions of the spaced type. The fully closed arch form, however, is an exclusive human type. 2. 2. A terminal plane forming a mesial step consistently allowed the first permanent molars of Macaca to erupt directly into proper cuspal interdigitation. This mode is rarely found in man. His proper molar occlusion requires a physiologic movement of tooth groups over a variable period of time. 3. 3. In Macaca there existed a distinct interval between the eruption of the permanent first molars and that of the permanent first incisors, during which an extension of the arches and a spacing of the deciduous incisors occurred. In man this phase is only rudimentary when, upon the eruption of the lower permanent first incisor, the still complete upper deciduous arch is somewhat spread in the anterior teeth. 4. 4. No enlargement of the arches was observed in Macaca during the replacement of the incisors. In man the expansion of the arches for the larger permanent incisors takes place during their eruption. Accommodating changes for the larger permanent incisors, therefore, are comparatively delayed and often reduced in man; they could be anticipated, however, in those deciduous human dentures which erupted with fully spaced anterior teeth. 5. 5. In the eruption order of the permanent teeth of Macaca the incisors were followed by the second permanent molars; after a pause, an almost simultaneous eruption of the posterior successional teeth occurred. In comparison to the whole eruption sequence of Macaca, that of man reveals a relative retardation of the accessional teeth and a relative acceleration of the successional teeth. Both phenomena were shown to be related to reduced longitudinal growth of the human jaws. The mandible behaves more progressively in this trend; this is responsible for increased incidence of crowded anterior teeth and deep overbite in modern man. 6. 6. The consistent end-to-end bite of the incisors in Macaca was found to be due to an equal forward development of both jaws in the absence of vertical growth of the alveolar process and mandibular ramus. The determining factor in the degree of incisal overbite in man is likely to be also the alveolar forward development and only secondarily the vertical growth. 7. 7. The dentofacial proportions in Macaca were seen to be subjected to considerable changes during development, whereas Brodie revealed in this respect a high individual consistency in man.

Human Saliva: IX. the Effect of Activation On Salivary Flow1

The great variation of results of calcium and phosphorus analyses of activated saliva have suggested that the many stimulating or activating factors render the value of A.S. rather questionable as a medium for comparative purposes. Very little information is available which gives the changes in salivary content produced by chewing a tasteless and inert activator, as for instance paraffin, and still less is known about the individual response to activation of saliva in persons with fast or slow flowing R.S. For this reason 30 individuals were requested to produce R.S. for 15 minutes and then for the production of A.S. to chew a 1 gram piece of paraffin 450 times. The experimental conditions were the same as previously reported (4, 28). The classification into Groups I and II again was made in order to study the influence of differences in rate of flow; Group I included 15 individuals with originally low rates of flow, i.e., up to 20 cc. R.S. per hour, aged 12 to 63 years; and Group II, 15 with over 20 cc./hr., aged 6 to 35 years. Table I demonstrates the changes in rate of flow from R.S. to A.S. in both groups. Even though the average rate of flow of R.S. (Table I, Columns A, bottom row) of Group I is approximately one-fourth that of Group II (9.0 and 39.7 cc./hr., respectively) the ranges for A.S. (Columns B) are-surprisingly enough-approximately the same,

Human Saliva XIV. Total Calcium Content of Resting Saliva of 650 Healthy Individuals

The fact that in published studies salivary calcium values have been found to vary between 2.2 and 145.9 mg. % (6) has prompted an investigation to determine ranges and arithmetic means of the total calcium content of mixed human resting saliva of a sufficiently large number of healthy individuals of representative age groups. With regard to description of material, experimental approach and technique of calcium analysis, the reader is referred to previous reports (11, 35). The -results were recorded as mg. % and mg./hr. values2 and then evaluated biometrically, permitting a concise description of numerical figures. Six hundred fifty -individuals were studied for whom the rate of flow values have been reported (11).

Human Saliva: XI. The Effect of Activation on Salivary Calcium and Phosphorus Content

Heidenhains law (23) stipulates that electric stimulation of salivary secretions in animals alters the composition of saliva in a definite way. In human beings, a relationship is found between the rate of flow of resting saliva and calcium and phosphorus content (11); however, it it is the reverse of Heidenhains law in that mg. per cent calcium and phosphorus values decrease rather than increase with higher speeds of secretion, and vice versa. Because of this observation, the changes in salivary composition produced by paraffin activation were studied.

The topogenesis of the mandibular permanent molars: A roentgenographic and histologic study in rhesus macaque

Abstract The roentgenographic and histologic study of the mandibles in a series of Rhesus monkeys leads to the conclusion that the topogenesis of each mandibular permanent molar involves the following processes. 1. 1. The growth of the ramus. It is governed by the chondrogenesis and endochondral ossification at the condylar head. These processes in turn induce membranous bone formation chiefly at the posterior border and to a lesser extent at the facial surface of the ramus correlated with modeling resorption at the anterior and lingual surfaces. The ramus is growing in a posterolateral direction, in some locations opposite to muscular stresses. 2. 2. The development of the germ. It is controlled by the differential growth of the odontogenic epithelium at distinct areas to engender preeruptive movements. These include first an axial downward rotation of the mesial portion followed by that of the distal portion; then the germ moves from the primary position parallel to the long axis of the ramus lingually into that of the dental arch. The final forward drift of the germ sets on a marked mesial migration of all posterior teeth of the dental arch. 3. 3. The correlation in time of both the ramal and the dental development. The buccal and superior portions of the alveolar process of each erupting molar develop at the expense of the former ramus by a process of modeling resorption while the lingual portion is apposited through periosteal bone formation at the time when the germ moves lingually. The alveolar bone proper always is formed endosteally during the active phase of eruption and thus constitutes a developmental entity with its supporting molar.

Growth and transformation of the mandibular joint in the rat II. Hypophysectomized female rats

Abstract The mandibular joint was studied in 79 hypophysectomized female rats at postoperative intervals ranging from 4 to 645 days. The transformations occurring following hypophysectomy are similar to those occurring in aging rats. The changes occur, however, very much earlier in the hypophysectomized rat; chondrogenesis is considerably slowed within four days after the operation. The ossification of the mandible of the hypophysectomized rat by twenty-eight days after operation is as advanced as in a 258-day-old normal rat. As in the normal rat some uncalcified cartilage remains in the condyle for long periods. The persistence of this tissue confers upon this joint the continued capacity for growth and remodeling.

Changes in endochondral ossification of the tibia accompanying acute pantothenic acid deficiency in young rats.

Summary The changes in endochondral ossification of the tibia accompanying acute pantothenic acid: deficiency in young rats have been investigated. Twenty deficient animals, 13 male and 7 female rats, were autopsied together with their controls at ages ranging from 3 to 16 weeks. The histologic changes observed were decreased growth of the tibia with marked impairment in chondrogenesis, osteogenesis and hematopoiesis. Four stages of morphologic changes were observed. Stage I, in which the ages of the rats ranged from 21 to 33 days, was characterized by unusual trabecular resorption, decreased osteoblast proliferation and edema of the bone marrow. In Stage II the ages ranged from 33 to 63 days and marked retardation of osteogenesis with some calcification in the epiphysis and blunt diaphyseal trabeculae was observed. The dominant feature of Stage III, from 45 to 72 days, was the beginning of epiphyseal cartilage calcification and the cessation of osteogenesis. Stage IV, from 78 to 109 days, was characterized by complete absence of trabeculae and the formation of a heavy layer of sealing-off bone below the epiphyseal cartilage. The role of pantothenic .atid and off additional factors such as pteroylglutamic acid, unknown vitamins and caloric restriction in these histologic changes is discussed.

The effect of hypovitaminosis a on bone healing and endochondral ossification in rats

Abstract The present study of bone behavior in vitamin A deficiency is based upon histologic and roentgenographic examination of the healing tooth sockets and the tibias of young male rats fed a purified diet deficient in vitamin A. After about thirty to thirty-five days on the experimental diet a clear-cut vitamin A deficiency was established and suboptimal maintenance does of vitamin A had to be administered in order to keep the animals alive. The main changes observed were as follows: 1. 1. Osteoblastic activity decreased, as evidenced by a considerable retardation of the formation of immature bone in the healing tooth socket. 2. 2. Ostcoclastic activity was suppressed or entirely about. This was clearly illustrated by the failure of remodeling resorption of the immature bone formed in the sockets of the deficient animals and by the failure of the remodeling of the tibial shaft. This lack of resorption was considered to be the mechanism responsible for the main changes in bones seen in vitamin A deficiency. 3. 3. The immature bone formed in the vitamin A-deficient rats contained more and larger osteocytes than the immature bone of the controls, and their cytoplasm and cell membrances were distinctly basophilic.