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Biomedical subjects

P H Buschang

Publications and source records attributed to P H Buschang.

At least 73 records · Page 4Linked to original sources
PubMed1991

Lip bumper therapy for gaining arch length.

With the use of pretreatment and posttreatment lateral cephalograms and study models, lip bumper therapy for two groups of 20 patients was evaluated. One group was treated with lip bumpers fabricated from stainless steel round wire covered with shrink tubing and activated every 2 to 3 months. The second group was treated with larger prefabricated lip bumpers covered with acrylic shields from canine to canine and activated every 4 to 5 weeks. Yearly rates of treatment change indicate that the type of lip bumper used and the method of clinical manipulation have no effect on mandibular incisor position. Both groups showed similar rates of controlled incisal tipping with the center of rotation at the apex. Dental movements of the posterior segment were significantly different between groups. The second group displayed significantly more molar tipping than the first group. The second group also showed significantly greater transverse expansion of the canines, first premolars, and first molars.

Acrylic Resins↗
PubMed1991

Growth status of children treated for unilateral cleft lip and palate.

Cephalometric distances, angles, and proportions were evaluated for 32 children 5 to 8 years of age treated for unilateral cleft lip and palate. The children were age and sex matched with untreated controls with normal skeletal relationships. The unilateral cleft lip and palate sample was treated by the same surgeon and orthodontist using the same techniques and appliances. Measures of overall facial proportions, facial convexity, and prognathism were not significantly different between the two groups. The primary group differences pertain to the posterior aspect of the maxilla, which is vertically short in the unilateral cleft lip and palate sample. Horizontally, the maxilla of the unilateral cleft lip and palate children was significantly longer, producing a steeper palatal plane. In addition, the zygoma and orbits of unilateral cleft lip and palate children were somewhat retruded; the posterior cranial base and total mandibular length also were longer in the unilateral cleft lip and palate children.

Analysis of Variance↗
PubMed1990

Mandibular growth prediction: mean growth increments versus mathematical models.

The aim of this study was to compare growth predictions obtained by adding mean annual velocities with predictions derived from a polynomial model of the population's growth curve. Given the child's previous measures at 11, 12 and/or 13 years of age, the cephalometric distance sella-gnathion at 15 years was estimated. Based on a sample of 223 boys and girls, the root mean square error decreased from 0.28 cm (males) and 0.18 cm (females) at 11 years, to 0.19 cm (males) and 0.12 cm (females) at 13 years. Root mean square errors were similar between methods, which was due to high correlations between measures across ages. Significantly, predictions based on mean increments were biased. They often over or underestimate growth for children who are larger and smaller than average. The observed bias was due to expected changes of variance associated with growth, which unconditional methods of prediction cannot control for. Predictions derived from growth models are conditional upon the child's size and are, therefore, unbiased.

Adolescent↗
PubMed1989

Modeling longitudinal mandibular growth: percentiles for gnathion from 6 to 15 years of age in girls.

Growth of the cephalometric landmark gnathion is modeled mathematically with multilevel statistical techniques. The findings, pertaining to a mixed longitudinal sample (N = 772) of 105 girls, 6 to 15 years of age, provide the most accurate descriptions of longitudinal mandibular growth presently available. Polar, rather than rectangular, coordinates are used to better distinguish between the amount and direction of growth. The velocity curve for sella-gnathion includes growth spurts during childhood (7.5 years) and adolescence (12.7 years). Growth direction of gnathion changes regularly throughout the age range, indicating a relative increase of vertical over horizontal growth. These reference standards serve as a basis for comparing and better understanding abnormal growth patterns.

Adolescent↗
PubMed1989

Natural selection is not related to reduced body size in a rural subsistence agricultural community in southern Mexico.

Adult Zapotecs are among the shortest Indians in Mexico. This study investigated whether reduced body size was an effect of genetic selection or a developmental effect of very poor nutrition and health. Fertility, offspring survival, and offspring prereproductive mortality were regressed on stature and weight of 205 multiparous adults (ages 20 to 72). The statistical analyses suggest that the exceptionally short stature of Zapotec Indians in this community is due to poor environmental conditions and not to genetic selection or adaptation.

Adult↗
PubMed1988

Socioeconomic variation in estimated growth velocity of schoolchildren from a rural, subsistence agricultural community in southern Mexico.

Socioeconomic variation in estimated growth velocities (annual growth increments) of several anthropometric dimensions was considered in schoolchildren from a rural, subsistence agricultural community in the Valley of Oaxaca in southern Mexico. The children (114 males, 99 females), 6-13 years of age, were measured twice, approximately one year apart. Annual growth increments were computed by subtracting measurements taken in the fall of 1978 from those taken in the fall of 1979. Information on household land holdings and appliances and parental occupation was used to compute an index of socioeconomic status (SES). Analysis of annual increments among upper SES (65 males, 45 females) and lower (49 males, 54 females) children indicated negligible differences. The results suggest that growth deficits evident in the children at school age occurred in infancy and early childhood so that there was little, if any, SES variation in growth rate at the school ages.

Adolescent↗
PubMed1988

Increased heterozygosity and child growth in an isolated subsistence agricultural community in the valley of Oaxaca, Mexico.

Gene flow and rate of inbreeding (delta F) were calculated from demographic data for a community previously reported to be isolated from outside genetic influences of immigration. Significant child growth differences caused by gene flow among children born to native parents (n = 287) and offspring of native-immigrant matings (n = 38) were found in fatness (triceps skinfold), body proportions (sitting height ratio), and size (leg length). No differences were found between the two groups in height, weight, sitting height, and arm circumference. Variation in absolute and relative leg length in this population parallels previously reported differences in adult body size and proportion associated with increased heterozygosity caused by gene flow in other populations in southern Mexico.

Adolescent↗
PubMed1988

Pubertal growth of the cephalometric point gnathion: multilevel models for boys and girls.

Two-level polynomial models are used to summarize the amount Sella-Gnathion (S-Gn) and direction Nasion-Sella-Gnathion (N-S-Gn) of growth changes for the cephalometric landmark gnathion. Growth descriptions pertain to a mixed longitudinal sample of 209 French-Canadian children 10-15 years of age. The boy's growth curve attains mean minimum prepubertal velocity at 10.8 years and maximum pubertal velocity at 14.1 years. The girl's curve follows a cubic pattern, attaining maximum pubertal velocity at 12.1 years. Boys are larger than girls throughout the age range. Variation between-subjects increases with age in a curvilinear fashion. Growth direction of gnathion is more horizontally directed for girls than boys. Small but significant changes in growth direction occur between 10 and 15 years of age.

Adolescent↗
PubMed1987

Adaptive significance of small body size: strength and motor performance of school children in Mexico and Papua New Guinea.

The postulated superior functional efficiency in association with reduced body size under conditions of chronic protein-energy undernutrition was considered in school children from rural Mexico and coastal Papua New Guinea. Grip strength and three measures of motor performance were measured in cross-sectional samples of children 6-16 years of age from a rural agricultural community in Oaxaca, Mexico, and from the coastal community Pere on Manus Island, Papua New Guinea. The strength and performance of a mixed-longitudinal sample of well nourished children from Philadelphia was used as a reference. The Oaxaca and Pere children are significantly shorter and lighter and are not as strong as the well nourished children. Motor performances of Pere children compare favorably to those of the better-nourished Philadelphia children, whereas those of the Oaxaca children are poorer. Throwing performance is more variable. When expressed relative to body size, strength is similar in the three samples, but the running and jumping performances of Pere children per unit body size are better than the relative performances of Oaxaca and Philadelphia children. Throwing performance per unit body size is better in the undernourished children. The influence of age, stature, and weight on the performance of Oaxaca and Pere children is generally similar to that for well nourished children. These results suggest that the hypothesized adaptive significance of small body size for the functional efficiency of populations living under conditions of chronic undernutrition varies between populations and with performance tasks.

Adolescent↗
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↗