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Biomedical subjects

W R Proffit

Publications and source records attributed to W R Proffit.

At least 55 records · Page 3Linked to original sources
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

Adjunctive orthodontic therapy in the treatment of juvenile periodontitis: report of a case and review of the literature.

Historically, the patient with juvenile periodontitis (periodontosis) presented as somewhat of an unknown entity to the orthodontist. With uncertainties concerning etiology still present, the orthodontist may be hesitant to undertake orthodontic treatment for the juvenile periodontitis patient. The literature pertaining to proposed etiologic factors and treatment modalities for juvenile periodontitis is briefly reviewed. Current evidence indicates that juvenile periodontitis patients have a compromised host response which allows an exaggerated susceptibility to certain gram-negative organisms. The disease is characterized by rapidly progressing bone loss, which is not associated with marked local irritation or gingival inflammation. Early diagnosis and conservative periodontal treatment have demonstrated good results. However, cases of advanced lesions or those cases that also involve malocclusion and potential occlusal traumatism may benefit from adjunctive orthodontic therapy. Successful management of a case involving multiple tooth loss along with a moderate degree of malocclusion is presented, with emphasis on the coordination of periodontic, orthodontic, and prosthodontic care. Orthodontic movement of teeth into previously affected areas was quite successful after a short healing period following extractions. A suggested protocol for the combined orthodontic, periodontic, and fixed prosthodontic management of the juvenile periodontitis patient is presented. Once the disease process has been arrested, the prognosis of each tooth is evaluated and possible rehabilitations, including orthodontic treatment and fixed prostheses, are planned. Periodontal evaluations are scheduled concurrently with orthodontic appointments to monitor the condition as tooth movement occurs.

Child↗
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↗
PubMed1983

Occlusal forces in normal- and long-face children.

In children aged from six to 11 yr, forces of dental occlusion during swallowing, simulated chewing, and hard biting are similar for normal- and long-face individuals. Forces in the normal- and long-face children are similar to those in long-face adults, but are about half those in normal adults. It appears that individuals with the long-face pattern fail to gain strength normally in the mandibular elevator muscles.

Child↗
PubMed1982

Extreme distal migration of the mandibular second bicuspid. A variant of eruption.

A five-year study of 26,264 panoramic radiographs found distal positioning of the mandibular second bicuspid associated with a missing adjoining first molar in one of every 505 patients. Following early removal of the first molar, there is a 5% to 10% chance that the second bicuspid will migrate distally. It usually continues until it contacts the root of the second molar, and then rotates up into occlusion adjacent to the parallel with that tooth. Mesial drift seldom occurs in this circumstance; the resulting space between lower first and second bicuspids remains. Early conservative management can be very important in these cases, making periodic x-ray examination advisable whenever a molar has been lost and the adjoining bicuspid has not yet erupted.

Bicuspid↗
PubMed1981

Primary failure of eruption: a possible cause of posterior open-bite.

Failure of posterior teeth to erupt fully into occlusal contact produces a lateral open-bite. These problems usually are attributed to a mechanical interference with the eruptive process, either ankylosis or some soft-tissue interference. In some patients, lateral open-bite is due to a disturbance of the eruption mechanism itself so that nonankylosed teeth cease to erupt. Influences on the eruption of teeth are reviewed, and possible causes of "primary failure of eruption" are discussed. The limitations of treatment for patients with eruption failure are described and illustrated by case reports.

Adolescent↗
PubMed1981

Augmentation genioplasty as an adjunct to conservative orthodontic treatment.

Augmentation genioplasty can serve as a valuable adjunct to orthodontic treatment. The borderline extraction patient with a good nasolabial angle, protruding lower incisors and a deficient chin often can be treated better by nonextraction orthodontics followed by advancement of the chin than by any regimen involving orthodontic extraction. Genioplasty also can be used to improve facial esthetics in the patient with a short mandibular ramus in whom mandibular advancement might well lead to unstable results. In some instances, genioplasty may be a way to overcome the appearance of facial asymmetry without requiring jaw surgery which would complicate a pre-existing adequate occlusion. As a relatively straightforward and predictable procedure, augmentation genioplasty should be used more often in conjunction with orthodontic treatment than it has been in the past.

Adolescent↗
PubMed1980

Early fracture of the mandibular condyles: frequently an unsuspected cause of growth disturbances.

Experience with patients referred to the Dentofacial Clinic at the University of North Carolina indicates that previous fracture of the mandibular condylar process may be involved in 5 to 10 percent of all severe mandibular deficiency or asymmetry problems. Since these fractures often go undiagnosed and since three fourths of the children with fractures have no growth deficits, the incidence of condylar fractures probably is much higher than commonly thought. Management of fracture patients immediately following the accident, during the postinjury stages of mandibular growth, and at completion or near-completion of growth is discussed.

Adolescent↗
PubMed1980

The role of research in advanced dental education.

Research is an integral part of quality advanced programs. Clinical research should be done in all departments where advanced dental education occurs, because this is the best way to improve the scientific base and rationality of clinical treatment. At present, many departments with postdoctoral programs lack faculty and others resources for research productivity. Programs to produce clinical faculty with research training are needed. The development of clinical research centers would offer the potential of combined clinical training and research. Combining existing resources for maximum effectiveness will be important in producing stronger programs.

Curriculum↗
PubMed1978

Equilibrium theory revisited: factors influencing position of the teeth.

The major primary factors in the dental equilibrium appear to be resting pressures of tongue and lips, and forces created within the periodontal membrane, analogous to the forces of eruption. Forces from occlusion probably also play a role in the vertical position of teeth by affecting eruption. Respiratory needs influence head, jaw and tongue posture and thereby alter the equilibrium. "Deviate swallowing" is more likely to be an adaptation than a cause of tooth changes. Patients with failure of eruption have been recognized and alterations in the eruption mechanism may be more important clinically than has been recognized previously.

Dental Occlusion↗
PubMed1977

Tongue pressures and tooth stability after anterior maxillary osteotomy.

Tongue pressures against the maxillary dentition during swallowing were measured in a series of ten patients who underwent anterior maxillary osteotomy for correction of protrusion. In these patients, tongue pressures were low initially, especially pressures by the sides of the tongue in the molar region. After surgical retraction of the incisors, tongue pressures increased, but the increases brought pressures up to normal levels from the previous abnormally low values. The data are consistent with the view that function (swallowing) adapts to oral form, rather than the other way around.

Deglutition↗