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Biomedical subjects

S Peck

Publications and source records attributed to S Peck.

At least 55 records · Page 3Linked to original sources
PubMed1992

The gingival smile line.

A comparative study was performed to examine the nature of the gingival smile line (GSL), a specific dentolabial configuration characterized by the exposure of maxillary anterior gingiva during a full smile. Five soft-tissue, three dental and three skeletal variables were selected, measured and reported for a GSL sample (n = 27) and a reference sample (n = 88), both consisting of North American white orthodontic patients with a median age of 14.4 years. The results indicated that the capacity to project a gingival smile was related to: anterior vertical maxillary excess and the muscular ability to raise the upper lip significantly higher than average when smiling. Other variables significantly associated with GSL were greater overjet, greater interlabial gap at rest, and greater overbite. Factors that did not appear associated with the GSL phenomenon were upper-lip length, incisor clinical crown height, mandibular plane angle, and palatal plane angle. Clinical aspects of GSL were discussed.

Adolescent↗
PubMed1992

A proportional analysis of the soft tissue facial profile in young adults with normal occlusion.

A proportional soft tissue profile analysis is presented, based on natural head position (NHP) and an extracranial vertical reference line through Porion. Twelve linear soft tissue variables and norms for 11 indices expressing vertical and horizontal soft tissue proportions of the face were obtained from lateral skull radiographs of 40 Swedish adults (20 males, and 20 females) with good occlusion. Sexual dimorphism, with larger dimensions in men than in women, was most pronounced in the vertical plane. With regard to facial soft tissue proportions, significant differences between men and women were found only for those indices which involved measurements of lower jaw prominence and facial height. The means and standard deviations for six indices in the female group were compared with corresponding data obtained from the Peck and Peck sample, which had been selected on esthetic grounds. The results showed a close match between the groups. The proportional soft tissue analysis is recommended for the treatment planning of patients scheduled for orthognathic surgery.

Adult↗
PubMed1991

Skeletal asymmetry in esthetically pleasing faces.

An x-ray cephalographic method was used to analyze 52 exceptionally well-balanced white adult faces for skeletal asymmetry in the posteroanterior (PA) projection. Three frontal facial lines were constructed using bilateral skeletal landmarks: latero-superior orbit (LO), lateral zygoma (Zyg), and gonion (Go). All subjects demonstrated measurable asymmetries. Data showed less asymmetry and more dimensional stability as the cranium is approached. A slight tendency toward right-side dominance was not statistically significant.

Adolescent↗
PubMed1990

Changes in standard electrocardiographic ST-segment elevation predictive of successful reperfusion in acute myocardial infarction.

The ability of the electrocardiographic ST segment to predict successful reperfusion after thrombolytic therapy remains controversial. To evaluate whether angiographically determined reperfusion could be predicted from changes in ST-segment elevation, the sum of ST-segment elevation in affected leads of the electrocardiogram was compared before and after thrombolytic therapy in 53 patients with acute myocardial infarction (AMI). Reperfusion status of the infarct-related artery was determined angiographically less than 8 hours from onset of symptoms. According to the Thrombolysis in Myocardial Infarction trial (TIMI) criteria, 33 patients had successful reperfusion (TIMI grade 2 to 3 flow) after thrombolytic therapy and 20 patients did not (TIMI grade 0 to 1 flow). Logistic multiple regression analysis showed that the proportional value for the shift in the sum of ST elevation, termed the "% ST change," was more strongly associated with reperfusion than the absolute measured difference in millimeters (chi-square = 11.34 vs 9.22). The entire spectra of sensitivities and specificities were determined to identify a level of the percent ST change with simultaneous high sensitivity and specificity. A 20% decrease in ST elevation provided such a level (88% sensitivity, 80% specificity). The positive and negative predictive values of a 20% decrease in ST elevation were 88 and 80%, respectively. These results suggest that a decrease of only 20% in the sum of ST elevation in the standard electrocardiogram after thrombolytic therapy is a useful noninvasive predictor of reperfusion status in patients with evolving AMI.

Cardiac Catheterization↗
PubMed1982

Slow late myocardial clearance of thallium: a characteristic phenomenon in coronary artery disease.

We extended the quantitative seven-pinhole method to follow the dynamics of thallium redistribution after exercise. We observed a pattern of slow late thallium clearance that appears to be characteristic of myocardium supplied by obstructed coronary arteries. In 28 subjects, quantitative thallium scintigrams (seven-pinhole tomography, circumferential count profiles) and blood samples for thallium concentration were taken immediately, 2 hours and 4 hours after maximal treadmill exercise. Twenty subjects had coronary artery disease (CAD) and eight were normal. The rate of thallium clearance from the blood (TCB) was compared with the rate of thallium clearance from each segmental region of myocardium (TCM, derived by ratioing corresponding segments of the absolute circumferential count profiles) between the 2- and 4-hour images. In seven of the eight normal subjects, TCM exceeded TCB in all regions of all images (specificity 88%). Seventeen of the 20 CAD patients had at least one region where TCM was less than TCB (sensitivity 85%). Of the 13 patients with multivessel CAD, 11 had multiple regions with TCM less than TCB. Using this criterion, we detected 31 of 39 obstructed coronary arteries. Of the 37 regions that were abnormal by this analysis, 30 corresponded to obstructed coronary arteries. In contrast, while conventional circumferential count profile analysis also was abnormal in 17 of the 20 CAD patients, it diagnosed multivessel CAD in only five of the 13 patients that had it. These results show that slow late thallium clearance from myocardium is characteristic of regions of myocardium supplied by diseased coronary arteries and that observation of this phenomenon may improve diagnostic sensitivity for the presence of multivessel CAD.

Coronary Disease↗
PubMed1979

Frequency of tooth extraction in orthodontic treatment.

Orthodontic extraction frequency describes the percentage of an orthodontic patient population experiencing extractions of one or more permanent teeth, excluding third molars. It is a useful statistical measure of the many variables associated with the extraction-nonextraction decision. For a study sample of 537 North American white orthodontic patients, the frequency of tooth extraction was determined as 42.1 percent. This is compared with a range of 6.5 percent to 83.5 percent reported in the world dental literature. Factors responsible for the enormous differences in orthodontic extraction frequency are explored. The study of extraction frequency offers a simple, valuable aid for the clinician to understand better the nature of his patient population, his treatment methods, and his rationalizations.

Adolescent↗
PubMed1975

Othodontic aspects of dental anthropology.

Variation in the size, shape, number, arrangement, and wear pattern of the teeth of man has long been an area of great interest to physical anthropologists. In this paper some of the remarkable variations to be found in the human dentition are identified and translated in orthodontic terms. Teeth are by nature imperfect structures, often just as disfigured individually as the malocclusions they form collectively. It is important that the orthodontist cultivates an anthropologist's eye for tooth variations. With this sensitivity he shall surely enlarge his understanding of the limitations of orthodontic therapy and shall appreciate the valuable role of tooth altering procedures in achieving treatment success.

Adolescent↗