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At least 19 recordsLinked to original sources
PubMed1977

Effects of occlusal attrition and continuous eruption on odontometry of rat molars.

Recurrent reports by others of posteruptive dimensional increase of the crowns of rat molar teeth were analyzed in the context of our present study of occlusal attrition, continuous eruption and alteration of the occlusal planes of rat maxillary molar teeth with age. Marked attrition of the anatomical crowns occurs, together with a considerable continuous eruption that increasingly brings the markedly convex mesial root of the maxillary first molar into the clinical crown. Further, a slight change in occlusal plane occurs. Previous workers used standardized planes of orientation and of registration prior to measurement, which masked the phenomena mentioned above. They thus mistakenly reported increased coronal dimensions.

Aging↗
PubMed1990

[Study of pain sensitivity based on the indicators of electro- odontometry in patients with depersonalization and depressive disorders].

Electroodontometry was used to examine the pain threshold and sensation threshold in patients with depersonalization, endogenous depression and in mentally healthy test subjects. The strongest differences in the thresholds were found on the anterior teeth. The patients with depersonalization manifested a considerable rise of the sensation threshold and to an ever greater degree of the pain threshold. In patients suffering from endogenous depression, both thresholds were decreased and coincided almost completely. It is likely that this fact is associated with a relatively higher incidence of the painful syndrome in patients suffering from depression.

Adolescent↗
PubMed1977

Development and size of the teeth of Macaca mulatta.

A cross-sectional sample of 151 skulls from Macaca mulatta of known age and similar rearing in U.S. Primate Centers was analyzed to determine age-related "norms" of stages of development and size of teeth. The stages of development from the follicle of a deciduous incisor in the fetus to completion of the root with apex closed of the permanent third molar were related to age. The age range observed for eruption of each tooth was noted and related to its stage of development. The crown of each erupted tooth was found to be completely developed, but growth of its root continued for a longer, indeterminate period. When a deciduous tooth was exfoliated, the crown of the permanent successor was found to be completed and root growth had begun. Measurements of both mesiodistal and faciolingual diameters and of crown length of the teeth in situ and of total length and root length on roentgenograms were examined for sexual dimorphism. The faciolingual diameter of the deciduous mandibular second incisor and of both second molars showed the greatest sexual dimorphism among both diameters of all deciduous teeth. The mesiodistal and faciolingual diameters of the mandibular premolars were found to be the best dimensions in discriminant functions for identifying sex in the absence of permanent canines.

Age Factors↗
PubMed1975

Evolutionary dental changes.

In the evolution of primates there has been a tendency towards reduction in jaw length and prognathism, mandibular canine size and first molar cusp number, and third molar presence. These oral structures were contrasted, and compared with cranial size, body height and weight, and finger length in 118 males and 102 females of the Burlington Growth Centre. Body weight was significantly related to canine width and to jaw length and prognathism. These relationships were stronger in the males than in the females. The evolutionary reduction in these dental dimensions may result from an evolutionary reduction in genetically determined body size. In the males the number of molar cusps was related to finger length and cranial height. Agenesis of third molars was related to the length of the maxilla in both sexes. In the females, canine width was related to the number of cusps of the first molars, agenesis of third molars, and length of a finger. Simultaneous reductions in dental structures were more frequent in the females.

Adolescent↗
PubMed1975

The functional adaptations of primate molar teeth.

Measurements were taken on the upper and lower molars of 37 species of primates and one tupaiid to assess the relative importance of shearing, crushing and grinding features. Significant correlations were found between pairs of allometrically standardized dimensions which measure the same molar function (shearing, crushing, or grinding). Correlations between pairs of dimensions which do not measure the same function are not significant. Second molar adaptations for shearing, crushing, and grinding, as well as the length of the second lower molar, and the total surface of the post-canine dentition are negatively allometric with respect to metabolic rate. Species which take different proportions of fruit, leaves, and insects in their diets have different molar structure. Frugivores have small teeth for their adult body size with poorly developed shearing, crushing, and grinding features on their molars. By contrast, leaf-eating species tend to have large teeth for their adult body size with well developed shearing, crushing, and grinding. The second molars of insectivorous species were found to parallel closely those of leaf-eating species. The two groups are clearly distinguishable from the former on the basis of body size alone: the smallest living primate leaf-eater is on order of magnitude larger than the largest living primate insectivore.

Adaptation, Physiological↗
PubMed1975

Dental reduction and the probable mutation effect.

A recent test of the probable mutation effect can be interpreted to suggest the operations of mutations under conditions of reduced selection in the late Pleistocene reduction of the human dentition.

Animals↗
PubMed1976

The dentition of the Indian Knoll skeletal population: odontometrics and cusp number.

Data on the permanent dentition of 153 individuals from the well known Indian Knoll skeletal population are presented. Mesiodistal and buccolingual measurements were taken with a Helios dial caliper. Cusp number of maxillary and mandibular molars are recorded. The Indian Knoll dentition is larger than many modern groups but smaller than Australoid or Mesolithic groups. With the exception of maxillary 12, males have larger teeth than females in both dimensions. The lower canine is the most dimorphic tooth. Through rank order correlation, an association was shown between the sexual dimorphism of the mesiodistal and buccolingual dimensions. Compared to modern groups, the Indian Knoll population displays a moderate degree of sexual dimorphism in tooth size. In general, the coefficients of variation were greater for the more distal teeth within morphological classes. Amounts of size variability did not differ significantly between the sexes; moreover, rank order correlations indicated that patterns of variability in both dimensions were similar for males and females. The predominant cusp number pattern for upper molars is 4-3-3 and for lowers 5-5(4)-5. No sex differences were shown for cusp occurrence or bilateral asymmetry in cusp number.

Female↗
PubMed1976

A fossil hominid frontal from Velika Pećina (Croatia) and a consideration of Upper Pleistocene hominids from Yugoslavia.

Fossil hominid remains dating to the Upper Pleistocene in Yugoslavia are reviewed. Particular emphasis is placed on the assessment of a hominid frontal from the site of Velika Pećina in northwestern Croatia. This specimen represents the earliest absolutely-dated hominid associated with the Upper Paleolithic in Europe. Also the hominid material from the site of Veternica is discussed, and data are presented on the new remains from Sandalja. It is concluded that no Neandertal remains, except for Krapina, have been found in Yugoslavia.

Cephalometry↗
PubMed1976

The genetics of shovel shape in maxillary central incisors in man.

From dental casts of 94 parent-offspring and 127 full-sib pairs, sampled from two Chilean populations, shovelling indices are computed to measure the degree of shovelling of maxillary central incisors quantitatively. Genetic correlations are computed to determine the role of genetic factors in explaining the variation in this trait. Assuming only hereditary factors to be responsible for the transmission of shovel shape, 68% of total variability is ascribed to the additive effect of genes.

Anthropology, Physical↗
PubMed1976

Arch form, tooth size, and occlusomandibular kinesis in the Ceboidea.

Correlations between dental morphology, arch configuration, and jaw movement patterns were quantitatively investigated in 23 ceboid species to elucidate integrative aspects of occlusal functional anatomy in an adaptive and evolutionary context. Differential maxillary-mandibular arch widths are primary in guiding lateral jaw movements. These movements are characterized according to their associated condylar shifts as either predominantly translatory or rotational. Predominantly translatory movements result from peripheral contact relationships between maxillary arches which are considerably wider posteriorly than their opposing mandibular arches. The greatest degree of mandibular movement is in the molar region in functional association with wide "primitive" maxillary molars, narrow mandibular molars, constricted maxillary intercanine widths, and narrow maxillary incisors. In contrast, predominantly rotational masticatory jaw movements results from differential arch widths which are greatest in the maxillary canine and incisor regions. Here most jaw movement is in the anterior segment and this is reflected in small maxillary-mandibular molar widths differences, a high degree of premolarization, wide-set maxillary canine teeth, and wide maxillary incisors. Possible selectional factors in the putative evolution of rotational predominance in mastication from the more primitive translatory pattern are discussed.

Animals↗
PubMed1977

Tooth, chin, bone and body size correlations.

Correlations of size of teeth, chin, bone and body were investigated in 118 males and 102 females of the Burlington Growth Centre. In the males, the mesiodistal widths of the mandibular lateral incisors and canines were independently related to the thickness of the cortex of the second metacarpal and to body weight. Bone cortex thickness was significantly related to metacarpal width in males and to body weight in females. Chin depth of the males was significantly related to bone width and to body height, negatively related to tooth width when bone width or body weight was held constant in partial correlations. Bone width and length were significantly related to body height in both sexes.

Adolescent↗
PubMed1977

A gracile hominid cranium from upper member G of the Shungura formation, Ethiopia.

A fragmentary hominid cranium with teeth, specimen L.894-1, dating from 1.84 m.y. BP in the Shungura Formation at Omo, is described. From its dental and cranial morphology and because of similarities to Olduvai Hominids 24 and 13 and Sangiran 4, among others, it is concluded that the specimen represents a member of an early species of the genus Homo (Homo habilis or Homo modjokertensis). The specimen shows approximal grooving on the premolars, pre-mortem chipping of the molar enamel, foramina ovale and spinosum divided by the sphenosquamosal suture, limited pneumatization of the mastoid region, and a possible interparietal bone. Sedimentological, ostracod, pollen, macrofloral, and taphonomic data indicate that the paleo-environmental context was a savanna/grassland or savanna woodland on the margin of a saline lake.

Cephalometry↗
PubMed1977

Metric dental change in the European upper paleolithic and mesolithic.

Evolutionary trends for dental reduction are presented for European Upper Paleolithic and Mesolithic samples. The analysis demonstrates that the greatest decrease in tooth size occurs between the two divisions of the Upper Paleolithic, while little and insignificant change characterizes the Late Upper Paleolithic/Mesolithic transition. Trends for tooth size over this period indicate that (1) human evolution does not stop with the appearance of "anatomically modern Homo sapiens," (2) changes in tooth size fluctuate with increases in the efficiency and complexity of cultural systems, and (3) the Early Upper Paleolithic sample should be considered transitional between Wurm II European Neanderthals and later Upper Paleolithic and Mesolithic groups.

Biological Evolution↗
PubMed1977

Heat stress, fluctuating asymmetry and prenatal selection in the laboratory rat.

Recent studies have demonstrated that stress may increase the fluctuating asymmetry of teeth and limbs in laboratory animals. The present study investigates the effects of heat on such parameters. Pregnant laboratory rats are exposed to temperatures of 33 degrees C during gestation. Increases in fluctuating asymmetry of dental dimensions as well as bone density are found for the pups of such females when compared to unstressed controls. A general increase in limb lengths is also reported for young of heat stressed animals. Prenatal selection with differential survival is suggested as a possible explanation for differences found between the experimental and control animals.

Animals↗
PubMed1977

On the meaning of increased fluctuating dental asymmetry: a cross populational study.

Suarez reports a greater magnitude of fluctuating dental asymmetry for Neandertal sample when compared with a sample of modern Ohio whites. He postulates that this greater antimeric variance could be due to a greater degree of inbreeding in the Neandertal populations. In the present investigation, the magnitude of fluctuating dental asymmetry is evaluated for Eskimo and Pueblo populations. These populations were found to exhibit dental variance of equal magnitude to that of the Neandertal population. As these populations are not highly inbred, a stress related mechanism is suggested to explain these observations and the inbreeding hypothesis is rejected. The implications of this mechanism to Brace's Probable Mutation Effect are discussed.

Bicuspid↗
PubMed1977

New fossil hominids from Laetolil, Tanzania.

New fossil hominid specimens from the Laetolili fossil locality in Tanzania are described. The material includes mandibles and teeth derived from reliably-dated deposits of Pliocene age. Preliminary descriptions, measurements and illustrations are presented.

Dentition↗