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Biomedical subjects

J T Mayhall

Publications and source records attributed to J T Mayhall.

At least 19 recordsLinked to original sources
PubMed1996

Torus mandibularis in 45,X females (Turner syndrome).

Ninety-three Finnish females with a 45,X chromosome constitution, 78 first-degree female, and 37 first-degree male relatives were examined to determine the frequency and expression of torus mandibularis. The results indicate that among adults the frequency of the trait was significantly lower and the expression weaker in the 45,X females than in male control relatives. A similar trend was observed in comparison to normal females. In juveniles the trend was reversed. Our findings suggest that the sex chromosomes may have an influence on the occurrence, expression, and timing of development of the mandibular torus. Sexual dimorphism in the manifestation of torus mandibularis may result particularly from the effect of the Y chromosome on growth.

Adolescent↗
PubMed1995

Tori mandibularis: a case report and review of the literature.

Many dentists have patients in their practice with mandibular exostoses, termed torus mandibularis. The majority of these asymptomatic, benign bony outgrowths remain undisturbed over the patient's lifetime. However, the tori occasionally need to be removed. The differential diagnosis for the tori are discussed as well as the indications and techniques for their removal. Various hypotheses concerning the etiology and epidemiology of torus mandibularis are also reviewed.

Adult↗
PubMed1992

Dental morphology of 45,XO human females: molar cusp area, volume, shape and linear measurements.

A three-dimensional analysis of the maxillary first molars of five 45,XO females and comparison with normal females and males demonstrated a reduction of cusp areas and volumes in the 45,XO females. Mesiodistal and faciolingual dimensions were also reduced. The reductions in basal area and volume were greater in the later developing, distal cusps. In normal females the second X chromosome apparently does not exert an effect on the cusp height but increases the basal area. The results further indicate that the Y chromosome in normal males increases both cusp height and basal area. The steepest cusps were found in 45,XO females while the shallowest were in the control males. Both sex chromosomes thus seem to affect the shape of the cusp but the resulting phenotypes differ.

Female↗
PubMed1991

Tooth crown size in 46, X, i (Xq) human females.

Permanent tooth crown sizes of six Finnish females with a 46, X, i(Xq) chromosome constitution (isochromosome for the long arm of the X chromosome) were measured from dental casts and compared with those of normal women, first-degree female relatives and 45, X females. Crown diameters of the 46, X, i(Xq) females were not only smaller than in the normal women but even smaller than the 45, X females. These findings can be considered indirect evidence that X chromosome gene(s) for tooth crown growth are most probably located on the short arm.

Chromosome Aberrations↗
PubMed1989

Three-dimensional analysis of the maxillary first molar crowns of Canadian Inuit.

The maxillary first molar crowns of 48 male and 38 female Canadian Inuit (Eskimos) were analyzed three-dimensionally by using moiré contourography methods. Cusp heights were significantly higher in males while the mesial and distal marginal ridges were more proximally placed in males. The metacone and the oblique ridge appeared to be better developed in the males. Comparison of the present results with published results for Dutch and Japanese indicated that the Japanese and Inuit had lower cusps that were more widely spaced than the Dutch. Correlation coefficients suggest that height measurements were positively correlated as were linear measurements. However, there were few significant correlations between height and linear determinations, suggesting that the development of the "width" of a crown is nearly independent of the development of the height of the cusps and crown.

Canada↗
PubMed1986

Dimensional and discrete dental trait asymmetry relationships.

Inuit (Eskimos) from the Foxe Basin region of the Northwest Territories, Canada, were studied to ascertain the amount of dimensional and morphological asymmetry in their dentitions. The results indicate that dimensional asymmetry does not appear to be greater on either the maxillary or mandibular teeth. Both types of asymmetry show partial conformity to the model of tooth fields with an increasing amount of asymmetry as one goes distally in each tooth group. The morphological asymmetry exception, the mandibular incisors, follows Dahlberg's "Field Concept." Rank-order correlations between the amount of dimensional asymmetry and morphological asymmetry reveal no detectable patterns. There appear to be no associations between the presence or absence of morphological asymmetry and the size of the tooth. This lack of association might be explained by differences in developmental timing of tooth dimensions and morphological traits; however, such a hypothesis requires experimental testing. In this population and those for which published results are available, it is practically impossible to overcome the "noise" level and test recent hypotheses regarding random dental asymmetry.

Canada↗
PubMed1982

Developmental patterns of human dental morphological traits.

A longitudinal series of casts of the deciduous and permanent dentitions of 827 children from Burlington Growth Centre study was examined for 5 traits: shovel-shape of the incisors, cusp six, cusp seven and protostylid of the mandibular molars, and Carabelli trait of the maxillary molars. The changing trait frequencies found support the concept of morphogenetic gradients of expression for non-metric traits from deciduous to permanent teeth. Tests of association showed that if shovelling was present on the deciduous incisors it would usually appear on the permanent successors. Tests of association between the other 4 traits on deciduous second molars and the permanent molars support the view that the second deciduous molar belongs to the total molar tooth district. This gradient expression of morphological traits would fit either the field or clone concepts, but it, and the intra-individual discordances for trait presence, probably reflects the great temporal spacing of dental development seen in man.

Adolescent↗
PubMed1979

A correlation of tooth wear and age among modern Igloolik eskimos.

The level of molar wear can be estimated reliably by measuring the cusp height. A correlation between age and the level of molar wear, expressed by a normalizing index (TWI) of cusp height, was found to exist in a sample of modern Igloolik Northwest Territories Eskimos. Not only was it possible to derive linear regression models to test the degree of correlation in the sample of 46 female and 39 male maxillary casts of Igloolik Eskimos, but the models were capable of accurately predicting the age of natives of the neighboring Hall Beach community. Sexual dimorphism in molar wear, perhaps attributable to differential bruxism, was demonstrated for the Igloolik sample. Based on the combined estimate of slopes for each maxillary molar pair for females and males, it was discovered that the male maxillary molars are worn approximately 30% more rapidly than female maxillary molars.

Adolescent↗
PubMed1978

Canadian Eskimo permanent tooth emergence timing.

To identify the times of emergence of the permanent teeth of Canadian Eskimos (Inuit), 368 children and adolescents were examined. The presence or absence of all permanent teeth except the third molars was recorded and these data subjected to probit analysis. Female emergence times were advanced over males. Generally, the Inuit of both sexes showed statistically significant earlier emergence times than Montreal children, except for the incisors. The present results do not support hypotheses indicating that premature extraction of the deciduous teeth advances the emergence of their succedaneous counterparts. There is some indication the controls of deciduous tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.

Asian People↗