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At least 1,063 records · Page 59Linked to original sources
PubMed1983

Three-dimensional measurements of the occlusal surface of upper first molars in a modern Japanese population.

Moiré photographs of the occlusal surface of first molars of Japanese children were taken by means of a specially designed moiré contourograph apparatus. They were then used for three-dimensional measurements. The heights of 4 cusps and some other points were measured by counting contour lines. Distances and angles between them were also measured. Sex differences of these measurements are found mainly around the metacone and hypocone. There is no clear correlation of the four cuspidal heights to the distances between them.

Dental Occlusion↗
PubMed1977

Dental variation in early eocene Teilhardinal belgica, with notes on the anterior dentition of some early tarsiiformes.

Statistical analysis of dental variation in specimens currently placed in Teilhardina belgica from the Belgian locality of Dormaal suggests that these specimens probably represent no more than a single biological species. Within this species sample, most specimens have an alveolus for 'P1' (or the anterior root of P2), but one specimen clearly lacks this alveolus. In the type specimen of Teilhardina belgica, the alveolus for the lower central incisor was only slightly larger than that for I2, a similarity to some other omomyids. The similarities shared by Teilhardina and Eocene Adapidae all appear to be retentions of primitive primate morphology, and thus they do not necessarily indicate any close relationship of early Omomyidae and Adapidae.

Alveolar Process↗
PubMed1978

A new omomyid primate from the Wasatch formation of southern Wyoming.

A new omomyid primate, Arapahovius gazini, is represented by many jaws and teeth and a few tarsal bones from a 15-meter stratigraphic interval at the base of the uppermost one-third of the Main Body of the Wasatch Formation, south-central Wyoming, USA. This primate is a conspicuous element in a faunule which lived at about the same time as the fauna of the Lysite Member of the Wind River Formation, estimated to be in the interval 52-50 million years before present. Individuals referable to the new omomyid are chiefly specialized by the intricate corrugation of enamel on the occlusal surfaces of their incisors, premolars and molars and by relatively molariform posterior lower premolars. These specializations may be interpreted as adaptation toward a more herbivorous-frugivorous diet. The tarsal bones referred to Arapahovius suggest that animals in this genus were habitual leapers. This new omomyid bears 'omomyine' and 'anaptomorphine' characters and may have been derived from an earlier Wasatchian (earliest Eocene) 'anaptomorphine' such as Tetonoides pearcei Gazin. Arapahovius seems to have had no phylogenetic successors.

Animals↗
PubMed1979

An analysis of tooth and body size relationship in five primate taxa.

The strength and the nature of the covariance between tooth and body size was investigated in Homo, Gorilla, Pan, Papio and Colobus. When sexes are combined in each taxon, the correlations are strong enough to compare the allometry coefficients of taxa, and the non-human taxa show a sufficiently strong linear relationship to compute 'interspecific' allometry coefficients. Allometry coefficients for each variable were not uniform among the taxa, and coefficients also differed from one variable to another. Computed 'intra' and 'inter' specific allometry coefficients from these data suggest that canine size will usually scale at a higher level than molar crown area, which is at most isometric, and not positively allometric with respect to body size. The consequence is that larger representatives of a taxon would be expected to combine relatively larger canines with a proportional, or relatively smaller, molar crown area. It is pointed out that these differences do not correspond to those found between 'gracile' and 'robust' australopithecines.

Animals↗
PubMed1986

[Dental enamel prisms of Mesopithecus pentelicus Wagner, 1839, compared with recent cercopithecids (Primates: Cercopithecidae)].

The dental enamel prisms of Cercopithecidae were examined by scanning electron microscopy. The main task of this study was to show the prism morphology representatives of different genera as well as their comparison with the fossil Mesopithecus pentelicus Wagner, 1839. The method used to show the enamel prisms was to etch the tooth surface with hydrochloric acid. In this way the outlines of the prisms were better contrasted for the descriptive morphology of the prisms than in etching with phosphoric acid. Two types were determined, in accord with the systematic division into subfamilies. In the subfamily Cercopithecinae elongated slender prisms were dominating, some with pointed, others with truncated tops. Most characteristic of this type were Macaca and Cercopithecus. An exception was Papio hamadryas which had broader, rounded prisms. In this way it differed largely from P. anubis whose prisms were short and mostly triangular. A very interesting fact was that very different patterns were found in P. anubis and P. hamadryas, although these two species are regarded as only one species by many authors. The second subfamily, the Colobinae, was characterized by broader prisms with a rounded shape, nearly as long as wide. Exceptions of the 'Colobine type' were at first Colobus with prisms little longer than wide and secondly Nasalis, with mostly parallel sides and truncated tops of the prisms. The prism outlines of Mesopithecus showed the greatest similarity to those of Presbytis which represents the characteristic 'Colobine type'. This fact confirmed the actual systematic position of the fossil Mesopithecus within the subfamily Colobinae. In addition to previously known primitive features of Mesopithecus within the subfamily of Colobinae, we present here a further concrete, common feature with asiatic Colobines.

Animals↗
PubMed1989

Canine tooth size variability in primates.

I present an analysis of canine tooth size variability in male and female primates. The coefficient of variation (CV = SD X 100/mean) as an index of canine size variability proved to be dependent on mean canine size in males and, to a lower extent, in females. Therefore, variability tends to increase with increasing values of mean canine size. Using residuals from the regression of log SD on log mean canine size in male and female primates, I analysed the contribution of diet, habitat and mating system to canine size variability. Habitat and mating system are known to influence to a certain extent the degree of sexual dimorphism in canine size. Given the well-known relationship between sexual dimorphism and phenotypic variability, it was suggested that these factors might influence variability in canine size. Everything else being equal, males of polygynous species are characterized by more variable canine sizes than males of monogamous species. Habitat and diet did not contribute to the level of variability observed in either males or females. It is proposed that a high level of variability in canine size may be related to the likelihood that enlarged canines evolved as a result of male-male competition for mates in polygynous species.

Animals↗
PubMed1989

The developing dentition and tooth structure in hominoids.

This review of hominoid dental development is presented in two parts. The first section reviews (1) the general relationship between dental development and life history in hominoids; (2) the methods used to document dental development, and (3) the nature of incremental growth markings in hominoid teeth. The second section builds on this and reviews the contributions to hominoid dental development that have been made by (1) studies of tooth emergence; (2) studies of tooth calcification stages, and (3) histological studies of incremental growth markings made either from sections of teeth or replicas of early hominid teeth prepared for scanning electron microscopy.

Animals↗
PubMed1991

An allometric perspective on primate postcanine tooth size.

The allometric relations of postcanine tooth size were evaluated in a sample of 66 adult Galago crassicaudatus (34 males, 32 females). Postcanine tooth area and length (estimated from mesiodistal and buccolingual measurements of upper and lower cheek teeth) were scaled to 4 cranial measures: bimaxillary width, maxillo-alveolar length, mandibular length and bigonial width. Postcanine tooth size was also scaled to body weight, body length and total skull length. It was found that postcanine surface and length were significantly correlated to the cranial measures employed in females, showing positive allometric scaling. These correlations were, however, lacking in males. In neither sex was postcanine size found to be significantly correlated to body length or weight.

Animals↗
PubMed1989

Effect of systemic fluoride on rat molar morphology. Stereophotogrammetric analysis.

Female Sprague-Dawley rats were divided into three groups. All three groups were given the same solid diet (with 1.6 ppm F). Group I was given deionized water, group II drank water with 5 ppm fluoride added, and group III had 50 ppm fluoride added. All females were mated with the same male. The pups were sacrificed at 28 days, and the mandibles were removed and cleaned. Three-dimensional representations of the occlusal surfaces of the 1st and 2nd mandibular molars were reproduced via computer-digitized images using stereophotogrammetry. Fissure depths and widths were measured, and 'volumes' of the fissures were computed. The fissure widths, depths, and volumes were compared statistically using unpaired t tests between groups (p less than 0.05). There were significant differences in fissure depth between groups I and II and between groups I and III. For fissure volumes, significant differences were found between groups I and III. The width of the fissure and the overall tooth size were not significantly different between fluoride-treated groups. Standardization showed a reproducibility to within +/- 40 mm with the stereophotogrammetric method.

Animals↗
PubMed2000

A controlled study of the morphometric changes in the primary dentition of pre-term, very-low-birthweight children.

The aim of the present investigation was to compare the dimensions of the primary incisors from pre-term children and full-term controls. One hundred and eleven pre-term children, consisting of 86 very-low-birthweight (< 1,500 g), 25 low-birthweight (from 1,500 to 2,500 g), and 169 full-term, normal-birthweight (> 2,500 g) children, donated a total of 572 maxillary and mandibular primary central and lateral incisors for study. The teeth were measured by means of a digital micrometer. The results showed that there was a dose-response effect of birthweight on tooth size. The very-low-birthweight teeth showed the smallest dimensions, the normal-birthweight controls the largest, and the low-birthweight teeth intermediate dimensions (p < 0.001). In the maxillary primary central and lateral incisors, and the mandibular primary central incisors, very-low-birthweight teeth were from 6 to 11% smaller in both mesiodistal and faciolingual dimensions compared with normal-birthweight teeth (p < 0.001). The largest differences were observed in the maxillary lateral incisors, where mean decreases of 0.58 +/- 0.45 mm in mesiodistal and 0.50 +/- 0.40 mm in faciolingual dimensions (11% reduction in both measurements) were observed. In addition, in the mandibular and maxillary lateral incisors of very-low-birthweight children, the left-sided teeth were significantly smaller than those on the right side in both mesiodistal and faciolingual dimensions (p < 0.03).

Analysis of Variance↗
PubMed2000

Inhibition of Wnt signaling by exogenous Mfrzb1 protein affects molar tooth size.

Wnt extracellular signaling molecules have essential roles as regulators of cell proliferation, migration, differentiation, and in epithelial-mesenchymal interactions involved in tissue morphogenesis. Frizzled integral membrane proteins have been shown to function as receptors for Wnt signaling molecules. Vertebrates also produce secreted proteins related to Frizzled receptors, Frizzled-related proteins (FRPs), which contain the cysteine-rich domain of Frizzleds and appear to function as Wnt antagonists. Tooth development is regulated by a reciprocal series of epithelial-mesenchymal interactions, and many Wnt signaling pathway genes are expressed in the developing tooth at these sites. Here we report the expression of one FRP gene, Mfrzb1, in the rostral mesenchyme of the mandibular primordium. Using explant cultures, we show that expression of Mfrzb1 in the mandibular mesenchyme is under the control of signals derived from the overlying epithelium. Bead implantation experiments in vitro show that FGF8 induces Mfrzb1 expression, whereas BMP4 and SHH proteins have no effect. We studied the effect of ectopic MFrzb1 protein on the developing tooth germs by transplanting explants treated with Mfrzb1 protein into renal capsules, and found it to retard tooth development. This suggests that Wnt signaling is required early in tooth germ formation and that interference with signaling via addition of an antagonist results in retarded development and formation of smaller teeth.

Animals↗