PubMed Health⌕ Search

Biomedical subjects

H W Fields

Publications and source records attributed to H W Fields.

At least 19 recordsLinked to original sources
PubMed2000

Facial growth and management of orthodontic problems.

This article enables pediatricians to identify and understand the implications of common facial growth problems in children and adolescents. Problems with facial growth can result in aesthetic and functional concerns. Using a simple method of clinical evaluation, pediatricians can identify facial growth problems in the anteroposterior, vertical, and transverse dimensions. These problems can then be referred for evaluation and treatment by various means. Because facial growth is the result of the interaction of genetic and environmental factors (some of which are functional), growth modification may be a possibility. Some problems may be camouflaged or treated by combined surgical and orthodontic means. Continued growth in early adulthood may enhance or detract from treatment results obtained in childhood or adolescence. These dynamic properties of the face make management of facial growth challenging but generally rewarding and successful because of substantial aesthetic and functional improvements.

Adolescent↗
PubMed1998

Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey.

Data from the third National Health and Nutrition Examination Survey (NHANES III) provide a clear picture of malocclusion in the US population. Noticeable incisor irregularity occurs in the majority of all racial/ethnic groups, with only 35% of adults having well-aligned mandibular incisors. Irregularity is severe enough in 15% that both social acceptability and function could be affected, and major arch expansion or extraction of some teeth would be required for correction. About 20% of the population have deviations from the ideal bite relationship; in 2% these are severe enough to be disfiguring and are at the limit for orthodontic correction. In Mexican-Americans compared to the rest of the population, incisor irregularity and both severe Class II and Class III malocclusions are more prevalent, but deep bite and open bite are less prevalent. Application of the Index of Treatment Need to the survey data reveals that 57% to 59% of each racial/ethnic group has at least some degree of orthodontic treatment need. Over 30% of white youths, 11% of Mexican-Americans, and 8% of blacks report receiving treatment. Severe malocclusion is observed more frequently among blacks, which may reflect their lower level of treatment. Treatment is much more frequent in higher income groups, but approximately 5% of those in the lowest income group and 10% to 15% of those in intermediate income groups report being treated.

Adolescent↗
PubMed1994

Skeletal jaw relationships: a quantitative assessment using elliptical Fourier functions.

Elliptical Fourier functions (EFF) were generated for the boundary outlines of the hard tissue craniofacial complex including the maxilla, mandible, and cranial base in order to quantitatively describe adult patients (n = 98) who were initially classified into nine skeletal groups by a combination of conventional cephalometric measures and clinical judgement. The mean residual fit of the EFF-predicted points and the original digitized data for the individual subjects ranged from .42 mm to .61 mm with a mean of .52 mm suggesting an accurate fit. Visual inspection of the individual plots confirmed this. Predicted classifications from a step-wise discriminant analysis based on EFF amplitudes were compared with the original classifications. The discordance rates for A-P and vertical plane classification were 21% and 13% respectively with an overall discordance rate of 33%. In general, a cluster analysis using EFF amplitudes did not identify clusters very similar in membership to the original groups; however, it was marginally successful in identifying members of the more severe groups and, like discriminant analysis, appeared to be more sensitive to vertical morphological differences. The overall lack of agreement between classifications and clusters based on EFF amplitudes and the original classifications may indicate that traditional skeletal categories such as those used in this study do not actually represent discrete groups.

Adolescent↗
PubMed1992

Stability of surgical maxillary expansion.

Stability after transverse expansion of the maxilla via Le Fort I osteotomy with segments was evaluated in 39 patients. The average expansion was 5.4 mm at the second molars, decreasing almost linearly to 2.8 mm at the first premolars. Postsurgical relapse also was greatest at the second molars, averaging 2.6 mm. The percentage of relapse was greatest posteriorly, decreasing from 49% at the second molars to 30% at the first premolars. Considerable variability in stability followed surgery: Three-fourths of the patients had some relapse at the first molars (greater than 3 mm in 28%), but one fourth were stable. Sixty-two percent of the patients had a net posttreatment gain in arch width at the first molars. No correlation was found between transverse relapse and the type of presurgical orthodontic tooth movement, the use of rigid fixation, or the use of an auxiliary stabilizing arch wire. The amount of postsurgical relapse was significantly greater in those who had concurrent mandibular surgery. To improve clinical results with surgical expansion, we recommend (1) moderate overexpansion at surgery for major transverse changes, (2) maintenance of the occlusal splint for at least 6 weeks, and (3) use of a lingual arch wire or auxiliary labial arch wire to maintain molar width during postsurgical orthodontics.

Adult↗
PubMed1991

Relationship between vertical dentofacial morphology and respiration in adolescents.

The relationship between vertical dentofacial morphology and respiration has been debated and investigated from various approaches. The purpose of this study was to use contemporary respirometric techniques to compare the breathing behavior of normal and long-faced adolescents. Sixteen normal and 32 long-faced subjects 11 to 17 years of age were chosen clinically and verified by means of a discriminant function. Vertical and anteroposterior facial form was assessed from lateral cephalometric radiographs according to the following measurement criteria: six skeletal angular, eight skeletal linear, four dental linear, and three skeletal ratios. Breathing behavior was quantified according to tidal volume, minimum cross-sectional nasal area, and percent of nasal breathing as assessed by pneumotachography, measurement of differential pressures, and inductive plethysmography. The data indicated that the normal and long-faced groups were significantly different with respect to lower face form, and each group in the study was comparable to groups that had been chosen by previous investigators. Multiple regression analysis demonstrated that the normal and long-faced groups had similar tidal volumes and minimum nasal cross-sectional areas, but the long-faced subjects had significantly smaller components of nasal respiration. These results illustrate that groups without significant differences in airway impairment can have significantly different breathing modes that may be behaviorally based, rather than airway-dependent.

Adolescent↗
PubMed1991

Craniofacial growth from infancy through adulthood. Background and clinical implications.

The purpose of this article was to enable the pediatrician to identify and understand the implications of common facial growth problems in children and adolescents. Problems with facial growth can result in aesthetic and functional complaints. Using a simple method of clinical evaluation, the pediatrician can identify facial growth problems in the anteroposterior, vertical, and transverse dimensions. These problems can then be referred for evaluation and treatment by a variety of means. By adopting a contemporary view that facial growth is the result of genetic and environmental factors (some of which are functional), growth modification becomes a real possibility. Unfortunately, some problems must be camouflaged or treated by combined surgical and orthodontic means. Continued growth in early adulthood can enhance or detract from treatment results obtained in childhood or adolescence. These dynamic properties of the face make management of facial growth challenging but generally rewarding and successful because of substantial aesthetic and functional improvements.

Adolescent↗
PubMed1990

Intracoronal radiolucencies within unerupted teeth. Case report and review of literature.

A panoramic radiograph obtained during orthodontic treatment revealed an intracoronal radiolucency within an unerupted permanent second molar. This unusual entity was successfully treated by surgical and endodontic intervention, followed by restorative and orthodontic treatment. These treatments enabled the tooth to maintain pulpal vitality, erupt, complete root formation, and function. This report will review the proposed etiologies for this condition, discuss the need for surgical intervention, and present the details of the case.

Calcium Hydroxide↗
PubMed1989

The effect of orthognathic surgery on occlusal force.

To investigate the effect of orthognathic surgery on occlusal force, such force was measured during maximum effort, chewing, and swallowing in 70 patients who had superior repositioning of the maxilla and/or mandibular advancement or setback. Larger changes in occlusal force than could be accounted for by the altered geometry were observed in all groups. Of 15 patients who had only superior repositioning of the maxilla, ten had greater than 20% increase in occlusal force, three had little change, and two showed a greater than 20% decrease. When the mandible was advanced, 11 of 34 patients had greater than 20% increase in maximum biting force, 11 had little or no change, and 12 had greater than 20% decrease. When the mandible was set back, six of the 21 patients had greater than 20% increase, nine had little or no change, and six had greater than 20% decrease. It appears that considerable change in bit force, which is not primarily related to jaw geometry, occurs after orthognathic surgery.

Bite Force↗
PubMed1989

Screening panoramic radiographs in children: prevalence data and implications.

The purpose of this paper was to review the rationale for the radiographic screening of asymptomatic pediatric patients and to report the prevalence of selected pathologic and developmental conditions using panoramic radiographs. Three observers participated in this retrospective study that utilized panoramic radiographs from 849 subjects, aged 3-9 years, chosen randomly from the School of Dentistry treatment records of the University of North Carolina at Chapel Hill. Findings indicated that 2.4% of the subjects had supernumerary teeth, 7.8% were missing permanent teeth, 9.1% had ectopic eruption, 0.1% had radiolucencies of the jaws, and 0.1% had radiopacities of the jaws. These prevalences are discussed in light of recent evidence concerning the risk/benefit ratio of the panoramic radiograph. We conclude that the panoramic radiograph is a poor projection for screening the dental needs of asymptomatic healthy children; alternative screening protocols should be examined.

Child↗
PubMed1986

Variables affecting measurements of vertical occlusal force.

Previous studies of occlusal force have provided conflicting results. The purpose of these studies was to determine whether the extent of vertical opening, contralateral occlusal support, or head posture influenced vertical occlusal forces during swallowing, simulated chewing, and maximum biting effort. Three samples of subjects with normal vertical facial proportions--one each of children, adolescents, and young adults--were evaluated to determine the effects of changes in small (2.5 vs. 6.0 mm) vertical separation of the first molars. A sample of young adults was used to evaluate changes in large (10-40 mm) vertical openings, and a sample of adolescents was used to investigate the effect of contralateral support and head posture. All between-group comparisons were evaluated using non-parametric statistics. For the small vertical openings, there was significantly more vertical occlusal force at 6.0 than 2.5 mm in children during swallowing and chewing but not during maximum biting effort. In adults, there was significantly more force during swallowing at 6.0 than at 2.5 mm separation, but no differences in chewing or maximum biting. Increasingly large vertical openings resulted in a progressive increase in maximum bite force to a maximum at about 20 mm, followed by a decrease and then a second increase to near-maximum force at about 40 mm for young adults. There were no significant differences in vertical force with or without contralateral support or between flexed, normal, and extended head postures at either of the small openings.

Adolescent↗
PubMed1984

Facial pattern differences in long-faced children and adults.

Vertical facial morphology has traditionally been studied by examining subjects chosen because of open bite/overbite or mandibular plane angle. The underlying skeletal and dental morphology associated with clinical facial appearance of normal and vertically dysplastic children and adults has not been well documented. The purposes of this study were to (1) describe vertical facial morphology in long-, normal-, and short-faced children and long-faced and normal adults, and (2) identify morphologic factors associated with the clinical evaluation of long-faced and normal subjects. Forty-two children, 6 to 12 years old, and forty-two young adults with varied vertical facial types were examined clinically and separated into three vertical classifications: long, normal, or short face. Lateral cephalometric radiographs were obtained in natural head position and seven angular, eighteen linear, and six ratio measurements were made. Descriptive statistics were used to characterize all groups, and intergroup differences were compared using analysis of variance for the three child groups and the t test for the two adult groups. For both long-faced children and adults, anterior total face height, mandibular plane angle, gonial angle, and mandibulopalatal plane angle were significantly greater than normal. Ramus height was not significantly different from normal in the children, but there was a tendency for long-faced adults to have short rami. Excessive dentoalveolar development was evident in long-faced children but not in adults. Factors associated with the clinical identification of vertical dysplastic subjects were identified by a principal component analysis. For each component, a variable highly correlated with that component was selected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

The effects of continuous axially-directed intrusive loads on the erupting rabbit mandibular incisor.

A cantilever beam strain-gauge transducer was used to apply continuous light intrusive loads (0.2-0.4 and 2.5 g) to unimpeded mandibular incisors. Tooth position was continuously monitored using a variable capacitance displacement transducer. After 4 days of unimpeded eruption, the animals were divided into three experimental groups: no axial loading (6 rabbits); 0.2-0.4 g of axial loading (3 rabbits); 2.5 g of axial loading (3 rabbits). During a 4-h period, light forces (0.2-0.4 g) slowed eruption to a stop, whereas a heavier force (2.5 g) intruded the teeth. The data support Burn-Murdoch's (1981) (Archs oral Biol. 26, 939-943) contention that the eruptive force of unimpeded continuously-erupting incisors is significantly less than previously thought.

Animals↗
PubMed1983

Occlusal forces in normal- and long-face adults.

Using both quartz- and foil-based piezo-electric force transducers, occlusal forces during swallow, simulated chewing, and maximum effort were evaluated in 19 long-face and 21 normal individuals. Forces were measured at 2.5 mm and 6.0 mm molar separation. Long-face individuals have significantly less occlusal force during maximum effort, simulated chewing, and swallowing than do individuals with normal vertical facial dimensions. No differences in forces between 2.5- and 6.0-mm jaw separation were observed for either group.

Adult↗