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Biomedical subjects

R Tanguay

Publications and source records attributed to R Tanguay.

At least 37 records · Page 2Linked to original sources
PubMed1986

Sexual dimorphism in the emergence of deciduous teeth: its relationship with growth components in height.

Sexual dimorphism in the emergence of the deciduous dentition of French-Canadian children may be explained by differences in recumbent length. Relative to the chronological age scale, boys are longer and their teeth emerge earlier than girls. Recumbent lengths attained at the exact age of emergence, as estimated by fifth-order polynomials fitted to each subject's serial data, are comparable between the sexes. Multi- and univariate analyses of variance show no significant sex differences in the lengths attained at the age of emergence of the deciduous teeth. These findings suggest that clinical standards for emergence of deciduous teeth scaled relative to length rather than chronological age are more accurate and efficient.

Age Factors↗
PubMed1986

Sexual dimorphism in mandibular growth of French-Canadian children 6 to 10 years of age.

Polynomial regression is used to model the mandibular growth of 28 girls and 26 boys who were followed longitudinally from 6 to 10 years of age. The pooled-within individual designs indicate that ramus height follows a linear pattern of size increase; corpus and total mandibular lengths display curvilineal, decelerating, patterns of growth over the age range. Multivariate analyses of variance reveal significant sex differences in size, favoring boys, for the two length measures at 6 years of age. Growth velocity for corpus length is also significantly greater in boys than in girls. Sexual dimorphism in the growth of total mandibular length is more complex, including differences in velocity and deceleration. Ramus height shows no significant pattern of variation between boys and girls for either size or growth velocity.

Aging↗
PubMed1986

A polynomial approach to craniofacial growth: description and comparison of adolescent males with normal occlusion and those with untreated Class II malocclusion.

Orthogonal polynomials are used to model the craniofacial growth of adolescent boys, aged 11 through 14 years, and to evaluate variation between normal occlusion and untreated Class II malocclusion. The results show linear growth (velocity) for the maxillary measures; their angular relationships to the cranial base remain stable throughout the age range. Mandibular measures show growth velocity and acceleration, indicating the adolescent growth spurt. For the majority (80%) of measures, boys with normal occlusion and those with Class II malocclusion were not significantly different. Mean growth velocity of basion-nasion is significantly greater for subjects with Class II, Division 1 malocclusion. Total mandibular length and the ANB angle display significant mean size (constant) differences between boys with normal occlusion and boys with untreated Class II malocclusion. The groups are comparable in growth velocity and acceleration, indicating that the size differences are established before 11 years of age and maintained during adolescence.

Adolescent↗
PubMed1985

Interrelationships among measures of somatic, skeletal, dental, and sexual maturity.

The interrelationships among five measures of physiologic maturity for 50 French-Canadian girls are evaluated--menarche, peak height velocity (PHV), 75% skeletal maturity, appearance of the ulnar sesamoid, and 90% dental development. The mean ages of occurrence of the events differed significantly (P less than 0.01). Menarche and 90% dental maturity showed the least variability. Ages of PHV, menarche, and 75% skeletal maturity were significantly correlated (P less than 0.05). Age of menarche was most closely associated with PHV. The appearance of the ulnar sesamoid was highly correlated with 75% skeletal maturity; both were equally related to the ages of PHV and menarche. The age at which French-Canadian girls attain 90% of their dental development showed no significant relationships with the other maturity indicators. The results imply that the mechanisms controlling dental development are independent of somatic and/or sexual maturity.

Adolescent↗
PubMed1985

Estimating variance components with BMDP for analyses of technical reliability.

Measurement reliability reflects the ratio of true (subject) to observed (subject plus error) variance. Analyses of reliability are limited due to difficulties in obtaining accurate estimates of the sources of variation upon which this relationship depends. This paper presents a simple analysis of variance procedure, using BMDP8V, for estimating the necessary variance components of mixed models, from which reliability may be assessed.

Analysis of Variance↗
PubMed1985

Adjusting craniofacial correlations for technical error.

Reliability estimates provide a means of adjusting observed correlations for technical error. The results show that the true correlations among 11 craniofacial landmarks are consistently higher than observed values. Consequently, the regression slopes defining these relationships are also increased. The less reliable two measures are, and the closer their joint reliability approximates the observed correlation, the greater the expected change in true correlation. Adjusting craniofacial relationships for technical error may substantially increase the proportion of variation explained, and thereby alter statistical inferences drawn from results.

Cephalometry↗
PubMed1984

Sexual dimorphism in the emergence of the deciduous teeth.

Exact ages of emergence of the twenty deciduous teeth have been investigated on a longitudinal sample of 195 French-Canadian children (113 boys and 82 girls). A multivariate analysis of variance yielded a significant overall sex difference (p less than 0.0001). It has been found that the emergence of the deciduous dentition in boys is more precocious than that in girls by about one month; this difference is present at the emergence of the upper central incisor and is maintained henceforth. The only notable exception to this pattern is the emergence of the first molars. Results of the present study, combined with those of previous research, suggest that sexual dimorphism in the emergence of the deciduous teeth could be mediated through ethnic factors.

Age Factors↗
PubMed1981

Sexual dimorphism in the development, emergence, and agenesis of the mandibular third molar.

Bilateral agenesis was encountered in about 9% of the cases, with no significant sexual difference. The right and left mandibular third molars had the same pattern of development and emergence. The slight advance of girls over boys at the crown-completion stage was similar to previous observations on other mandibular teeth, particularly the second molar. The root development course of the third molar was faster in males than in females; this sexual dimorphism was much greater for retarded cases than for advanced cases. At the apex closure, the difference between median ages of males and females was 1.5 yr. Alveolar emergence tended to occur at a lower developmental stage in advanced cases compared with retarded cases.

Adolescent↗
PubMed1972

Studies on mitochondria. II. Mitochondrial DNA of thoracic muscles of Schistocerca gregaria.

The buoyant densities of the nuclear and mitochondrial DNA from the thoracic muscles of Schistocerca gregaria were found to be 1 702 and 1.689 g/cm(3), respectively, corresponding to guanine plus cytosine (G + C) content of 42.2 and 30% A preliminary treatment of the mitochondrial pellet with DNase (25 degrees C, 20 min) is necessary to eliminate the contaminating nuclear DNA. The mitochondrial DNA renatures readily after heat denaturation and incubation at 65 degrees C. The DNA released from the mitochondrial pellet by osmotic shock consists of circular open and closed molecules with a contour length around 5 micro The instability of insect mitochondria in in vitro preparations is discussed.

Animals↗