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J T Mayhall

Publications and source records attributed to J T Mayhall.

At least 19 recordsLinked to original sources
PubMed2006

Clinical and histopathological examination of experimental bite marks in-vivo.

Under rigorously controlled laboratory conditions, mechanically induced simulated human bite marks were made on pig skin to enable the clinical and histopatholgical study of experimental bite marks in-vivo. A series of bite marks were created on the abdomen and thorax of live anaesthetized juvenile pigs at specific times just prior to and after death. Following the release of the biting force clinical observations of antemortem wounds revealed slow diminishment of the bite indentations presumably due to dermal elastic recovery. Minutes after euthanasia of the animals, the indentations of the teeth from the postmortem bite marks faded rapidly. After the biting process the animals were placed on either the right or left side and this side was maintained until necropsy to examine for dependant and non-dependent side differences. All bite mark injuries located on the non-dependent side revealed specific pattern characteristics. However, on the dependent side whether the bite mark was antemortem or postmortem in areas of livor mortis, no clear pattern was visible. Histologically, the observations for each bite mark specimen were categorised by the presence or absence of extravasated red blood cells in the fatty or muscle layers. The histopathological findings correlate with the clinical observations of antemortem and postmortem bite marks located on the non-dependent side in regard to muscular erythema and extravasated red blood cells. It is clinically difficult to comment on temporal relationship of a bite mark in relation to time of death in areas affected by blood-pooling seen on the dependent side. In these situations, histopathological studies could be a reliable alternative to provide information regarding antemortem or postmortem injuries.

Adipose Tissue↗
PubMed2004

Prevalence of early childhood caries among First Nations children, District of Manitoulin, Ontario.

BACKGROUND: Epidemiological studies of Aboriginal communities in Canada and Native American populations in the United States have reported that early childhood caries (ECC) is highly prevalent. The purpose of this study was to determine the prevalence of ECC and dental caries in the First Nations population of 3- and 5-year-old children in the District of Manitoulin, Ontario to assist in developing effective dental health promotion strategies. METHODS: All 3- and 5-year-old children in elementary schools and day-care centres in seven First Nation communities were eligible for the survey examination. Three-year-old children at home and 5-year-old children attending school off-reserve in six of the communities were also eligible for epidemiological survey examination of oral health status including caries, gingival and soft tissue conditions. Cases of ECC were defined as children with caries or restorations on two or more primary maxillary incisors or canines or those having a total decayed, missing, filled primary teeth (dmft) score of 4 or greater. RESULTS: A total of 87 children (59% 5 years old, 54% females) were examined. Seventy-four per cent of children had one or more carious lesions. Forty-five cases of ECC were found, a prevalence of 52%. The mean dmft score for cases was 7.5 (95% CI 6.5-8.4) and 0.8 (95% CI 0.5-1.1) for non-cases (P < 0.001). Boys in both age groups were more likely to be affected by ECC than girls. CONCLUSION: Our results indicate that dental caries and ECC are highly prevalent in this population, with ECC cases having 6.7 more dmft than non-cases.

Child, Preschool↗
PubMed1997

A new, three-dimensional method for determining tooth wear.

A new technique combining moiré contourography and digital image analysis allows the three-dimensional description of molar wear. It is possible to describe the amount of tooth material lost in a given time, e.g. mm3/year, and the differing amounts of wear on individual cusps. The moiré technique can be used in conjunction with more conventional quantitative techniques or by itself to assist in age determination in a population. It can be used to describe small amounts of wear that hitherto were difficult to quantify. It is not recommended where the wear includes the greatest convexity of the crown (height of contour) or affects the central fossa.

Age Determination by Teeth↗
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↗