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Biomedical subjects

D B Giddon

Publications and source records attributed to D B Giddon.

At least 19 recordsLinked to original sources
PubMed1999

Comparison of preferences in lip position using computer animated imaging.

The objectives of this study were to examine the esthetic preferences of lip position in males and females, and to compare them with each other and with a common orthodontic standard using a custom computer animation program. The sample consisted of 53 young adult subjects, 25 males and 28 females. The sample was divided into orthodontically treated and untreated subjects. ANOVA and Scheffé tests were carried out to determine differences between the responses of the various groups. Also, t-tests were used to compare subjects' responses to a commonly used orthodontic standard (Ricketts' E-line). The results indicated a sex-effect, with females preferring fuller lips than males. Significant differences were also found between orthodontically treated subjects and untreated subjects, with untreated subjects preferring fuller lips. Differences were significant at p<0.05. Furthermore, both males and females preferred lip fullness greater than the Ricketts' values.

Adolescent↗
PubMed1999

Comparison of perceptions of computer-animated left- and right-facing profiles.

PURPOSE: Although scientific publications differ in displaying left- or right-facing profiles, there are few systematic studies of the possible effects of directional biases and laterality on patients' and clinicians' perceptions of treatment need, outcomes, and satisfaction. As part of a research program to quantitate the physical bases of the perceived zone of acceptability and most-pleasing facial profiles, responses to computer-animated left- and right-facing soft-tissue profile images were compared and related to eye and hand preference. MATERIALS AND METHODS: Standardized left-facing, soft-tissue profile images were captured in color and digitized. The right-facing profile was created by reversing the left profile image to display a mirror image. Using imaging and customized morphing software, retrusive and protrusive extremes were created, from which transitional frames were developed to display five features of the soft-tissue profile: upper lip, chin, bimaxillary position, lower face height, and mandible. One left- and one right-facing profile for a Class II division 1 female, and Class III male were randomly presented to 24 subjects who were asked to indicate: 1) acceptability by pressing a mouse button and releasing the button when the images were no longer acceptable; and 2) most-pleasing image by pressing the mouse button once. RESULTS: No differences were found between left- and right-profile images for zone of acceptability, midpoint of the zone of acceptability, or most pleasing; nor was there any relation to laterality measures. However, consistently higher intercorrelations among the features for the zone of acceptability were found for the left- than for the right-facing profiles for retrusive to protrusive and protrusive to retrusive excursions measured in millimeters (p < .001). The bimaxillary position accounted for most of the variance in judgments of acceptability with greater influence on the left than on the right profile. CONCLUSION: With the increasing use of computer-imaging in dental practices, the influence of psychophysical and other environmental variables on perception must be considered.

Adolescent↗
PubMed1999

Computer-animated comparison of self-perception with actual profiles of orthodontic and nonorthodontic subjects.

To determine if motivation for adult orthodontic treatment is influenced by self-perception, a computer morphing program was developed to animate discrete digitized photographs of facial profiles. It was hypothesized that orthodontic patients are less tolerant of variations in their profiles than nonorthodontic patients. Sixteen orthodontic and 14 nonorthodontic adult patients were presented with animated distortions of 5 features of the lower third of their own profiles. They were asked to identify the zone of acceptability in the changing profile and to indicate the single most pleasing distortion and their perceived and preferred profiles, for comparison with their actual profile. Although orthodontic subjects did not differ from nonorthodontic subjects in the zone of acceptability of their own profiles, they were less tolerant (smaller zone of acceptability) of variation in features of a standard control face. Orthodontic subjects, however, had a larger disparity between the most pleasing and at least one feature of their actual profile than did the nonorthodontic subjects. Orthodontic and nonorthodontic subjects were equally accurate in their ability to identify their own profile features. This unique method of measuring self-perception offers the clinician the advantage of providing a dynamic range rather than a single point of acceptable change to the patient. Moreover, this interactive computer program will enable patients to actively participate in treatment planning decisions by communicating preferences for variations in facial profile distortions.

Adult↗
PubMed1998

Presurgical profile preferences of patients and clinicians.

The purpose of this study was to compare the presurgical preferences for profile change of patients seeking orthognathic surgery with the preferences of "significant others" and clinicians. In this study, five features of lateral profile images of 11 patients scheduled for orthognathic surgery limited to the mandible (ie, set-back or advancement) were animated for continuous change with the use of customized morphing software and video imaging. Each patient profile was evaluated by the patient, a significant other, three orthodontists, and three oral surgeons. As the feature animated between two extremes, the zone of acceptability was established by depressing the computer mouse when the changing feature became acceptable and releasing the button when the image was no longer acceptable. In a separate task, the participants were asked to indicate the most pleasing position. An analysis of variance was used to find a significant difference (P <.017) in the zone of acceptability for all five profile features among all groups of evaluators. From smallest to largest, the order of the mean zone of acceptability was: orthognathic patient < oral surgeon < significant other < orthodontist. No consistent differences were found, however, for either the midpoint of acceptability or most pleasing distortion among the patients, significant others, and professional groups. In conclusion, it was demonstrated that (1) patients having orthognathic surgery were able to use this new video imaging method to communicate to clinicians what they find acceptable; and (2) although all groups had similar preferences, orthognathic patients had the lowest tolerance for deviation from the preferred image.

Adolescent↗
PubMed1997

Influence of magnitude of horizontal and vertical deformation on preference for morphed faces.

The purpose of this study was to assess whether the magnitude of the extreme horizontal or vertical deformations of morphed facial features influenced judgments of acceptability or preference of the facial soft tissue profile. Twelve judges responded to 5 changing features of 2 faces with clinically divergent malocclusions under 3 stimulus conditions, i.e., the magnitudes of the distortions were biased in the direction of preferred change, equally distorted in both directions and opposite to preferred change. For each condition, judges responded by pressing a mouse button when the feature became "acceptable" and releasing it when no longer acceptable and by pressing the button when the most pleasing distortion appeared. A small significant shift in the mean acceptability and preference was found for some features. Differences between the faces, however, remained constant, indicating that magnitude of distortion has little effect on acceptability or preference for changes in soft-tissue profiles.

Adolescent↗
PubMed1996

Quantitative comparison of computerized discrete and animated profile preferences.

To determine the physical bases of subjective judgments of facial appearance, two computer presentations of discrete soft tissue profile (STP) images were compared with the same images appearing in an animated format. The images were judged by 24 volunteers. The influences of the number and order of faces presented, gender, and dental knowledge were evaluated. Fifteen to eighteen digitized distortions of the chin, upper lip, mandible, bimaxillary relationship, and lower face height were prepared from STPs of four faces (two males and two females) representing Class I, Class I with microgenia, Class II division 1, and Class III. The judges responded to each discrete alteration as acceptable or unacceptable and with a separate rating from 1 to 6. Each feature was then "animated" by presenting the distortions serially at 1.25 frames/sec in counterbalanced order six times, from both the extreme protrusive (P) and retrusive (R) distortions. The judges indicated an acceptance zone by pressing a button when the face became acceptable and releasing if when no longer acceptable. The rating responses were more favorable than the simple acceptable/unacceptable dichotomy. Neither of the discrete methods was found to be as reliable as the animated method. Significant differences were found for the animated responses between the aggregate midpoint of acceptability of Class II division 1 and Class III for all features except bimaxillary relationship, thus providing a criterion-based validation of the animated method. The dental judges had a greater tolerance of feature variations than did the nondental judges. By establishing a zone of acceptability in addition to a single midpoint of acceptability, the animation technique may be more clinically useful than discrete presentation for determining individual as well as group perceptions of physical change.

Adult↗
PubMed1996

Comparison of two computer animated imaging programs for quantifying facial profile preference.

To establish the physical basis of subjective judgements of facial appearance, two novel computer-imaging programs differing in method of preparation and presentation of 5 features of the facial soft-tissue profile of 4 faces representing 4 different classifications of dental occlusion were compared. Images of facial soft tissue of 5 features were digitized and "animated" from 16 discrete distortions or morphed from the two extremes of each feature. 12 volunteer judges responded to both the "animated" and morphed presentations by pressing the computer mouse button when the image became acceptable and releasing the button when the image was no longer acceptable. They also pressed the mouse button when the most pleasing distortion appeared from either direction. Aggregating responses to counterbalanced trials and features across judges yielded high correlations between the programs for midpoint of acceptability. Although both programs provide reliable and valid measures of subjective acceptability of present and proposed changes in facial morphology, the new morphing program is more user-friendly than the "animated" method.

Adult↗
PubMed1995

Orthodontic applications of psychological and perceptual studies of facial esthetics.

Historically, orthodontists have not reconciled the paradox that their diagnostic and treatment decisions are based largely on objective morphological considerations and their patients' decision-making centers on esthetic expectations and other subjective factors related to self-image and outcome. Key to the unraveling of this discrepancy is a greater understanding of the role of perception by self and others in orthodontic diagnosis and treatment. Esthetics can be defined as relating to feeling, and perception can be defined as the organization of environmental stimuli. Various physical, psychological, and social factors that affect perceptual judgments are described and related to the development and maintenance of self-image and/or concept. The impact of these self and/or other perceptions of dentofacial attractiveness on motivation for seeking orthodontic care are discussed. New quantitative approaches to relate morphological changes to perception of facial appearance are reported.

Beauty↗
PubMed1981

Pharmacology of local anesthetic agents.

Local anesthetic agents may be classified according to their intrinsic anesthetic potency and duration of activity. Procaine and chloroprocaine are relatively weak, short-acting drugs. Lidocaine, mepivacaine, and prilocaine represent agents of intermediate potency and duration of action. Tetracaine, bupivacaine, and etidocaine are highly potent, long-acting agents. The toxicity of local anesthetic drugs is usually due to inadvertent rapid intravascular injection or extravascular administration of an excessive amount. Intravascular toxicity is correlated with intrinsic anesthetic potency, whereas toxicity following extravascular injections is a function of physiological disposition characteristics of the various agents, such as rate of vascular absorption, rate of tissue redistribution, and rate of metabolism. The central nervous system is most susceptible to the toxic effects of local anesthetic agents. Signs and symptoms of CNS excitation followed by depression are the most common manifestations of local anesthetic toxicity. Cardiovascular depression may also occur following administration of excessive doses of local anesthetic agents or following high spinal or epidural anesthesia.

Anesthetics, Local↗
PubMed1980

Determinants of facial profile self-perception.

Using a simple profile-simulation device, forty-two orthodontic patients and an equal number of nonorthodontic patients indicated how they thought they appeared and how they would like to appear for comparison with actual cephalometrically determined profiles. Consistent with other studies of the self-perception of body parts, patients in both orthodontic and nonorthodontic groups underestimated the protrusiveness of their lips. For the psychological measures, the actual and perceived magnitude of the protrusiveness correlated significantly with anxiety and dissatisfaction with their profiles. Futher research is suggested to develop a more refined simulation technique for use by orthodontists and surgeons interested in obtaining reliable and valid measures of patient-perceived needs and expectations of corrective procedures.

Adolescent↗
PubMed1979

Psychosocial aspects of craniofacial disfigurement. A "State of the Art" assessment conducted by the Craniofacial Anomalies Program Branch, The National Institute of Dental Research.

The psychosocial sequelae of craniofacial disfigurement may have as great an impact on the patient as the strictly physical aspects of the problem. Very little systematic work has been focused directly on these effects. The following broad recommendations would constitute initial research steps in this field: Development of satisfactory measures of physical attractiveness and their use in studies to explore the role of craniofacial features in over-all physical attractiveness. The establishment of valid metrics for assessing the severity of craniofacial anomalies through the use of both physiologic and behavioral measures, thus constructing a broader definition of what constitutes a craniofacial handicap. Studies of the relationships among physiologic and behavioral variables using recently developed statistical techniques and computer methods to determine the psychosocial consequences of craniofacial disfigurement. Studies of the process through which persons with various types of malocclusion decide to seek and complete treatment. The studies would include the patients' demographic characteristics, self-perceptions, perceptions of them by others, and the complex patient-clinician interactions during the treatment programs.

Body Image↗
PubMed1976

Consumer and provider attitudes toward dentist and expanded auxiliary functions.

Consumers, dentists, dental students, dental assistants, dental hygienists, dental assistant trainees, and dental hygiene students in Massachusetts were surveyed for their attitudes toward the concept of expanded-duties auxiliaries. The Osgood sematic differential technique was used, in which study participants were asked to respond to line drawings of a dentist or an auxiliary performing each of three different procedures: cutting tooth structure, placing a restoration, and taking radiographs. The results indicate that most of the groups perceived significant differences between cavity preparation by the dentist and by the auxiliary: they were modierately positive toward the former, near neutral toward the latter. Groups were more positive toward cavity restoration, generally perceiving fewer, but still significant, differences between the dentist and auxiliary as operatiors. All groups were most positive toward taking radiographs and perceived no difference between the two operators. Of all groups, the dentists perceived the greatest difference between operators; dental hygienists and dental hygiene students were the most positive and saw the least differences between operators. Consumers were the least positive to all procedures and perveived only modirate differences between the two operators. In other words, the consumers did not seem overly concerned with who provided the dental care; they just did not like the services themselves. In the study, the consumer was more concerned with the procedure than with the different operators, whereas the dentist was more concerned about the operator.

Attitude↗