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Biomedical subjects

S C White

Publications and source records attributed to S C White.

At least 37 records · Page 2Linked to original sources
PubMed1998

Comparison of vertical ground reaction forces during overground and treadmill walking.

PURPOSE: The purpose of this study was to compare vertical ground reaction forces walking overground with vertical foot-belt forces for treadmill gait. METHODS: Twenty-four subjects walked overground and on a treadmill at three speeds (slow, normal, and fast), and at comparable cadences and stride length at each of the speeds. Treadmill and overground vertical force curves were normalized to 100% of stance time and compared using Person's product moment correlation. Selected measures from vertical force records were compared between the two modes of locomotion via repeated measures ANOVA (P < 0.05). Post-hoc analysis consisted of paired t-tests with Bonferroni correction. All comparisons were made across conditions (treadmill vs overground) at each of the three walking speeds. RESULTS: The pattern of reaction forces were similar. Correlation between curves were 0.998, 0.983, and 0.983 for the slow (1.03-1.05 m.s-1), normal (1.40-1.44 m.s-1) and fast (1.65-1.71 m.s-1) walking trials. Small (5-9%) but significant differences in force magnitude for the two forms of locomotion were evident during mid-stance for normal (P = 0.00009) and fast (P = 0.0007) walking speeds and in late stance for normal (P = 0.0014) and fast (P = 0.0005) trials. CONCLUSIONS: Although the patterns of the vertical reaction forces for the two forms of locomotion were nearly identical, small but significant differences in selected force magnitudes were evident. The interpretation of locomotion data collected on a treadmill should consider that forces during mid- and late-stance may be different than if the subject walked overground.

Adult↗
PubMed1997

Comparative performance of digital and conventional images for detecting proximal surface caries.

OBJECTIVE: To evaluate the performance of a digital CCD system for detecting proximal surface caries compared with film. METHOD: Three hundred and twenty extracted human teeth were imaged by making direct digital (Schick Technologies, Inc) and conventional film images (E-speed) of each. A total of 16 experienced dentists scored the proximal surfaces of these teeth for the extent of enamel and dentin lesions. The teeth were subsequently sectioned to determine the actual caries depth. RESULTS: The sensitivity of the CCD system was consistently lower than film while the specificity of the CCD system was consistently higher. The accuracy of CCD and film images was not significantly different, neither when sensitivity and specificity were averaged nor when accuracy was weighted to reflect caries prevalence of 2, 5 or 10%. The predictive values of both positive/negative outcomes were virtually identical for the CCD and film images. The interrater variability in lesion confidence scores with digital images was comparative with film. CONCLUSIONS: Dentists using a direct digital CCD system performed as well in interpreting proximal surface caries as with E-speed film. This work suggests that for this task these two competing systems are diagnostically comparable.

Analysis of Variance↗
PubMed1997

Muscle function and gait in patients with knee osteoarthritis before and after muscle rehabilitation.

Patients with knee osteoarthritis (OA) have reduced functional capacity and muscle function that improves significantly after quantitative progressive exercise rehabilitation (QPER). The effects of these changes on the biomechanics of walking have not been quantified. Our goal was to quantify the effects of knee OA on gait before and after QPER. Bilateral kinematic and kinetic analyses were performed using a standard link-segment analysis on seven women (60.9 +/- 9.4 years) with knee OA. All functional capacity, muscle function and gait variables were initially reduced compared to age-matched controls. Muscle strength, endurance and contraction speed were significantly improved (55%, 42% and 34%, respectively) after 2 months of QPER (p < 0.05), as were function (13%), walking time (21%), difficulty (33%) and pain (13%). There were no significant changes in the gait variables after QPER. To use the QPER improvements to the best advantage, gait retraining may be necessary to "re-programme' the locomotor pattern.

Aged↗
PubMed1997

Orthodontic residents' indications for use of the lateral TMJ tomogram and the posteroanterior cephalogram.

The purpose of this study was to determine the selection criteria used by orthodontic residents for ordering a corrected lateral tomogram (LT) of the temporomandibular joint (TMJ) and a posteroanterior cephalogram (PAC) for the diagnosis of patients needing orthodontic care. The impact of the radiographs on their treatment plans was also assessed. We conducted a study of the 144 new patients assigned to eight orthodontic residents during a two-year period. The residents responded through questionnaires describing their rationale for ordering the radiographs. A LT was ordered for twenty-eight (19 percent) of the patients. The most common reasons cited for requesting the LTs were TMJ clicking (67 percent) and pain (33 percent). The residents also perceived a need to order the LT for medico-legal protection in 85 percent of these cases. The LT tended not to have an impact on treatment planning. A PAC was ordered thirty-eight times (26 percent). The most common reasons cited by residents for ordering a PAC included clinical findings of facial asymmetry (41 percent) and maxillary airway anatomy (24 percent). Medico-legal protection was a perceived need in only 12 percent of the cases. While the PAC had no impact on treatment planning for 56 percent of the cases, they did define the transverse problems as dental or skeletal for 38 percent of the cases. Six patient traits were statistically associated with PAC requests: difficulty chewing, abnormal TMJ, TMJ clicking, facial asymmetry. crossbite, and midline discrepancy. The teaching of appropriate selection criteria for ordering these radiographs needs to be emphasized early in a resident's training.

Adult↗
PubMed1997

The Lovelace Award presentation of the Society of NASA Flight Surgeons.

The following speech was presented at the Society of NASA Flight Surgeon's annual luncheon meeting on May 11, 1995 in Anaheim, CA. The Randolph C. Lovelace Award is presented annually by the Society. Stanley C. White, M.D., had a very distinguished career in Aerospace Medicine, including working with the Air Force's Man-In-Space and Man-In-Space-Soonest Programs, and, later, as the first Flight Surgeon assigned to the NASA Space Task Group. For these, and numerous other contributions, Dr. White was chosen to receive the Society of NASA Flight Surgeons' 1995 Lovelace Award at the 66th Annual Scientific Meeting of the Aerospace Medical Association. Dr. White, who was a personal acquaintance of Dr. Randy Lovelace for whom the award is named, then captivated the audience with a fascinating speech about Dr. Lovelace. Furthermore, he admonished us to remember the legacy of Dr. Lovelace and the many lessons his wisdom still teaches us today. The following is Dr. White's presentation.

Aerospace Medicine↗
PubMed1996

Relationships between clinician variability and radiographic guidelines.

This study evaluated the replicability of clinical measurements under careful calibration of multiple dentists and how the replicability can relate to their use as selection criteria in guidelines for prescribing dental radiographs. For 48 consenting patients, three dentists clinically examined each patient and recorded the presence of all clinical findings using standardized selection criteria. The examinations were performed independently of each other, but with periodic conferences of the dentists to clarify general measurement criteria. The degree of agreement among the dentists is described by the interrater agreement kappa for several standard clinical indications such as rating of caries, periodontal disease, and tooth mobility. Almost perfect agreement was obtained for tooth status, restoration size, and restoration material. Moderate agreement resulted for measures of caries, defective restoration presence, and gingival recession presence. Only fair agreement was obtained for other periodontal disease measures. The relationship between extent of agreement and guidelines' results was examined for the FDA Guidelines. The differences among the dentists' clinical measurements resulted in considerable differences among the radiographs that were selected by the FDA Guidelines' criteria. Even so, the missed disease rates for 490 patients in a larger study of the FDA Guidelines' efficacy were very low and did not vary greatly among the three dentists. We conclude that guidelines' criteria can be quite robust to variation from dentists' clinical measurement differences, as seen from the FDA Guidelines applied under the idealized setting where the dentists are periodically recalibrated through group discussions of the clinical measurements' definitions and interpretations.

Adolescent↗
PubMed1996

Decision-support systems in dentistry.

Decision-support systems hold a specialized body of knowledge in computerized form such that the non- specialist can obtain expert-level information. The goal of these systems in clinical sciences is usually to assist patient care by providing the clinician with improved diagnosis or treatment planning. Decision-support systems consist of three components: the user interface through which the clinician or patient enters signs or symptoms, the set of data describing clinical knowledge in the domain of the program, and an inference engine to manipulate the data set in light of a patient's specific signs or symptoms to arrive at a diagnosis or treatment plan. Such systems usually use one of three mechanisms of analysis alone or in combination: classification trees, Bayesian conditional probabilities, or rule-based (heuristic) systems. Numerous problems must be solved before decision-support systems will become commonplace in clinical practice. Data entry of patients' signs and symptoms is often tedious. The quality of the clinician's initial observations is of great importance in determining the quality of the output. It is also often difficult to convey to a program the subtlety of clinical information observed. Knowledge required in clinical data bases is often unavailable or imprecise. As these and other challenges are addressed we can anticipate increased utility of decision support programs in the future.

Algorithms↗
PubMed1995

Efficacy of TMJ radiographs in terms of expected versus actual findings.

OBJECTIVES: The purpose of this study was to measure the amount of new information contributed by temporomandibular joint tomograms beyond that anticipated by the patient's clinical presentation. STUDY DESIGN: The results of a clinical examination and history, including a video of patient interview, and dental casts of 105 patients with a temporomandibular disorder were presented to a panel of general dentist evaluators with some experience in temporomandibular disorders. These evaluators then described the radiographic findings they anticipated. Lastly they examined temporomandibular joint tomograms for each of the study patients and scored their findings. RESULTS: The temporomandibular joint tomograms revealed unanticipated osseous changes in 61% of case judgments of condyles and 47% for the temporal bone or 34% and 22%, respectively, when subtle changes were excluded. Unexpected condyle positional findings were revealed in 31% of the patients. When stratified by clinical class, osteoarthritis and internal derangement, false-positive and false-negative interpretations were 12.1% and 25.5%, respectively, for osteoarthritis, and 12.2% and 17.3% for derangement. CONCLUSIONS: The fairly high rate of unexpected new osseous and positional findings supports the need for tomograms in patients with a clinical diagnosis of derangement or osteoarthritis.

Facial Pain↗
PubMed1995

Impact of TMJ radiographs on clinician decision making.

OBJECTIVES: This study examined the influence of lateral and frontal temporomandibular joint tomograms on the initial diagnosis and treatment plan of patients having facial or preauricular pain or temporomandibular joint disorders. STUDY DESIGN: Five or six general dentists, all with experience in treating patients with disorders of the temporOmandibular joint, examined records of 105 patients from a university-based orofacial pain clinic. The examiners proposed a diagnosis and treatment plan for each patient without the benefit of tomograms. They then repeated this procedure after study of the radiographs. The impact of the radiographs was measured as the change in pre- versus postradiographic diagnosis and treatment plan. RESULTS: The availability of temporomandibular joint tomograms changed or modified diagnosis in 65% of the judgments and influenced treatment recommendations in 40%. These changes were substantive for 21% of the diagnoses and 22% of the treatment plans. The strongest correlation to changes in both diagnosis and treatment plan was with radiographic detection of osseous changes. New information about condyle position had less effect on clinical decisions. CONCLUSIONS: These findings indicate that temporomandibular joint tomograms play a valuable role in influencing clinician's diagnosis and treatment plan of patients with disorders of the temporomandibular joint.

Decision Support Techniques↗
PubMed1995

Efficacy of FDA guidelines for prescribing radiographs to detect dental and intraosseous conditions.

OBJECTIVES: This study compared the FDA guidelines for ordering dental radiographs to a conventional full-mouth examination for the detection of intraosseous disease and conditions affecting teeth other than caries. STUDY DESIGN: We examined 490 patients and selected posterior bite-wing and periapical views as indicated by the patient's signs or symptoms. We compared the radiographic findings with the use of this selected set of radiographs to those from a full-mouth set of radiographs to determine the rates of missed disease when the FDA guidelines were used. RESULTS: The most commonly missed intraosseous findings were osteosclerosis, unerupted teeth, periapical radiolucencies, and primary root tips. Periapical radiolucencies that were most probably periapical cemental dysplasia were missed in six patients. The most commonly missed dental findings were resorbed roots and pulp stones. Three instances of dens in dente were missed. CONCLUSIONS: When we used the FDA guidelines, the number of missed intraosseous and dental conditions was small and most likely inconsequential given the range of variability in dental diagnosis and treatment.

Adolescent↗
PubMed1995

Efficacy of the FDA selection criteria for radiographic assessment of the periodontium.

The diagnosis of periodontitis is generally made on the basis of a clinical examination supported by radiographic evidence of bone loss. Recent guidelines promulgated by the US Food and Drug Administration recommend that periapical radiographs be ordered on the basis of clinical signs and symptoms indicating the probable presence of disease. This study evaluated the effectiveness of the FDA Guidelines for ordering radiographs for new adult dental patients as related to assessment of the periodontal condition of the patient. We examined 490 patients and determined the periapicals needed to supplement the posterior bitewings based upon the patient's clinical findings. We measured the reduction in the number of radiographs ordered as well as the extent of missed alveolar and furcation bone loss resulting from the use of the selected set of radiographs compared with a complete set. Four hundred thirty-three subjects had at least one clinical sign of periodontitis present in their mouths, and 264 demonstrated radiographic evidence of alveolar bone loss. Of the 460 subjects on whom periodontal probing was conducted, two-thirds demonstrated periodontal probing depths in excess of 3 mm; almost half showed evidence of bleeding upon probing. Individuals with clinical signs of periodontitis had, on average, 10 periapicals ordered--more than twice the number as those with no sign of periodontitis. Of the 2,415 teeth with radiographic findings of proximal or furcal bone loss, 152 sites of bone loss (6%) were missed when the selected set of films plus the posterior bitewings was used.

Adolescent↗
PubMed1995

Clinical and historical predictors of dental caries on radiographs.

This report evaluates the efficacy of the clinical predictors of caries proposed in the USA FDA guidelines for prescribing dental radiographs. The clinical findings that best associate with the presence of any caries where a history of pain, a defective restoration, unusual calcification, and an abutment tooth for a fixed or removable prosthesis. There is a group of measures of periodontal disease that were also weakly associated with the presence of caries. The best predictors of caries extending into the dentin were the presence of clinically defective restorations, a history of pain, and signs of periodontal disease. Proximal lesions are likely to appear on teeth with defective restorations, unusual calcification or large or deep restorations. The best predictors of radiographic root caries are periodontal findings such as furcation involvement, increased mobility, a history of periodontal therapy and gingival recession. While the specificities for these findings were generally high, the sensitivities and positive predictive values were usually under 50%, and often much lower. Thus these clinical findings cannot successfully be used as exclusive criteria for ordering radiographs for caries detection. Because caries is found fairly frequently, and because we are unable to identify tooth-specific criteria with clinically useful sensitivity and specificity values, these data support the FDA panel recommendation of bitewing examinations for all new patients and at periodic intervals for recall patients.

Confidence Intervals↗
PubMed1995

Assessing the FDA guidelines for ordering dental radiographs.

In 1988, the U.S. Food and Drug Administration issued guidelines to help dentists reduce the amount of X-ray exposure to patients without reducing the quality of care. This study assesses the efficacy of those guidelines. The authors examined 490 patients and ordered radiographs as indicated by the FDA guidelines. Using the guidelines, they ordered a mean of 9.7 radiographs out of a 17-film series, a reduction of 43 percent compared with a full-mouth series. The authors conclude that dentists can reduce a patient's exposure to X-rays by using these guidelines with a low level of missed radiographic findings, most of which would have no effect on the patient's treatment.

Adolescent↗
PubMed1995

The effects of unilateral knee immobilization on lower extremity gait mechanics.

The purpose of this study was to identify the effects of knee immobilization on uninvolved lower extremity joints during gait. Video and force platform data were collected for seven subjects walking normally (N) and with the knee fixed at three flexion angles: 0 degrees (B00), 10 degrees (B10), and 20 degrees (B20). A bilateral, sagittal plane link-segment model was used to determine lower limb kinematic and kinetic measures. Mean data from three normal and five braced gait trials were compared using one-way repeated measures ANOVA (P < 0.05). Significant increases in involved limb (IL) ankle generation work (J.kg-1) during propulsion were evident: (N = 0.249, B00 = 0.295, B10 = 0.293, B20 = 0.308). There were significant increases in peak IL hip power (W.kg-1) in early stance (N = 0.638, B00 = 1.056, B10 = 1.018, B20 = 1.097) and in IL hip absorption work (J.kg-1) during late stance (N = 0.049, B00 = 0.080, B10 = 0.082, B20 = 0.079). The hip of the uninvolved limb (UL) displayed significant increases in generation work (J.kg-1) in early stance (N = 0.089, B00 = 0.183, B10 = 0.149, B20 = 0.179). Normal kinematic and kinetic patterns of other joints were changed with knee immobilization. The major effects were increases in the magnitude of IL peak hip and ankle joint kinetic measures. Fixing the knee in 10 degrees of flexion resulted in the fewest significant changes in normal gait mechanics.

Adult↗
PubMed1994

Absence of radiometric differentiation between periapical cysts and granulomas.

A recent study reported that the mean density of periapical cysts was greater than that of periapical granulomas. This study, which used a larger sample size and a robust method for standardization of density and contrast between images, found no difference between the radiographic density of cysts and granulomas classified by microscopic evaluation. Cysts tend to be larger than granulomas, but there was wide variation in size of both types of lesions. There was no significant correlation between the density of a lesion and its size.

Absorptiometry, Photon↗
PubMed1994

Efficacy of FDA guidelines for ordering radiographs for caries detection.

This study evaluated the effect on caries diagnosis of using the Food and Drug Administration (FDA) guidelines for ordering radiographs on a sample of new adult patients seeking general dental care at a dental school clinic. These guidelines recommend posterior bitewing views accompanied by supplemental periapical views as indicated by the patient's clinical signs or symptoms. We compared the findings from the use of this protocol to those from a full-mouth set of radiographs made on the same new patient. We examined 490 patients and ordered periapical radiographs in accordance with the FDA guidelines, namely, when there was some clinical sign or symptom suggesting the need for radiographs. A full-mouth set of radiographs was obtained, and both the full and selected sets were evaluated separately. We found that 95% of our patients had one or more carious lesions, with an average of 5.7 carious teeth per patient. Of the 2808 carious teeth detected in the study, 1949 (69%) were found radiographically and 1564 (56%) were found clinically. Indeed, 1244 (44%) of the carious teeth were detected only by radiographic examination. Use of the FDA guidelines resulted in a 43% reduction in the number of radiographs ordered. Reduction in the number of images made on patients resulted in failure to detect 93 lesions (3.3%) located on 88 teeth in 11.4% of the study patients. Most of the missed lesions (2.9%) were radiographically confined to the enamel of anterior maxillary teeth. Only 36 of the missed lesions (1.6% of all radiographic lesions) extended into the dentin. We believe that this number is very small and most likely inconsequential compared with the considerable diversity among dentists regarding radiographic detection of caries, as well as the diversity of opinion regarding the indications for restorative treatment.

Adolescent↗