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Biomedical subjects

S C White

Publications and source records attributed to S C White.

At least 19 recordsLinked to original sources
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

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↗
PubMed1994

Detection of mineral loss in approximal enamel by subtraction radiography.

The purpose of the present study was to determine whether digital subtraction radiography will improve detectability of small, mechanically prepared defects within dental enamel. Lesions with an extent of 1 mm in vertical direction and representing 5% to 10% mineral loss in the direction of the x-ray beam were prepared in eight extracted molars. Radiographs of teeth with defects were subtracted from radiographs taken before the lesions were prepared. Seven observers evaluated the images using a five-point confidence rating scale (receiver operating characteristic technique). Examination of the original radiographs showed increasing accuracy of radiographic interpretation with increasing mineral loss as judged from the areas beneath the receiver operating characteristic curves. The same observation was made using subtraction images with and without contrast enhancement. There was no indication that subtracted images provided better diagnostic validity than the original radiographs. In conclusion, subtraction images do not seem to improve the diagnosis of well-defined lesions within dental enamel.

Dental Enamel↗
PubMed1993

Uncoupling the correlates of locomotor costs: a factorial approach.

Although the metabolic cost of running has been found to vary systematically with running speed and body mass in animals, no mechanistic model of cost determination has been widely accepted. Because two suggested cost determinants--mechanical power output and the rate of force application--covary with running speed when gait (stride frequency) is unconstrained, examining the influence of each factor on cost has been problematic. We experimentally uncoupled the usual relationships between three readily manipulated cost correlates--speed, stride frequency, and mass distribution--to study the determinants of the cost of running in humans along a section of the cost response surface. Two levels of each cost correlate were used in a factorial design in which subjects ran at all eight combinations of factor levels while rate of oxygen consumption (VO2), mechanical power, and contact time were measured as response variables. Contact time and mechanical power were measured from high-speed cinefilm. Mechanical power accounted for 88%, and contact time (rate of force application) 57%, of speed-related VO2 variation. Variation in cost produced by changes in stride frequency and mass distribution were largely explained by mechanical power. Contact time was not significantly correlated with overall variation in VO2, while mechanical power output explained 80% of that variation. For the range of conditions tested, we conclude that the mechanical power derived from muscular contractions is an important determinant of the cost of running. While we have shown that the rate at which muscles shorten is not the sole determinant of the cost of running, the extent to which this factor influences cost remains unclear.

Analysis of Variance↗
PubMed1993

Radiographic secondary caries prevalence in teeth with clinically defective restorations.

Decisions to replace existing restorations are often based on clinical findings of margin discrepancies and other restoration defects. Previous studies have suggested that such findings do not correlate well with the actual presence of secondary caries, and that treatment should be deferred until caries is clinically or radiographically evident. The purpose of this study was to assess the frequency with which clinically defective restorations are associated with radiographic secondary caries. As part of a study to assess the efficacy of guidelines for the ordering of dental radiographs, 6285 restored teeth in 490 subjects were examined clinically and radiographically by three calibrated investigators. Specific criteria were used to determine whether restorations were intact or defective. Of the total, 822 teeth (13%) were judged to have clinically defective restorations. Of these, 113 teeth (14%) had radiographic secondary caries. Of the 5463 teeth with intact restorations, 5% had radiographic secondary caries. We found that the likelihood of radiographic secondary caries was nearly three-fold higher for defective restorations than for intact restorations. The large percentage (86%) of defective restorations with no radiographic secondary caries suggests, however, that replacement of all defective restorations due to risk of secondary caries may constitute overtreatment. The use of defective restoration status and presence of radiographic secondary caries as a combined criterion for replacement may potentially reduce such overtreatment. The prevalence of secondary caries under defective restorations should be determined clinically so that the usefulness of combining the criteria of defective restoration with those of radiographic secondary caries can be evaluated.

Analysis of Variance↗
PubMed1992

An algorithm for ordering pretreatment orthodontic radiographs.

A study was conducted to identify selection criteria for ordering pretreatment orthodontic radiographs. Thirty-nine orthodontists evaluated six test cases. They provided information on the rationale for ordering each specific radiograph and the impact of the radiograph on the diagnosis and treatment plan. Skeletal relationship of the jaws was the most common indication for a radiograph request, followed by root formation/length and molar position or development. Of the radiographs, 16% produced a change in diagnosis, and 20% produced a change in treatment plans. The criteria specified for the radiographs, their impact, and relevant information in the literature were used to develop an algorithm or set of decision rules that, when tested on the six test cases, resulted in a 36% reduction in the total number of radiographs.

Airway Obstruction↗
PubMed1992

1992 assessment of radiation risk from dental radiography.

Recent studies suggest that the lifetime cancer risks from exposure to low levels of ionizing radiation may be greater than previously estimated. This review first summarizes the findings of these studies as they pertain to dental radiology, then uses their concepts in combination with dosimetry from the dental literature to estimate the radiation risk from dental radiology. Estimation of risk from groups of exposed individuals requires use of mathematical models that fit the epidemiological data. The ICRP estimates that a single brief whole-body exposure of 1 Gy to 10,000 people results in about 500 additional cancer deaths over the lifetime of the exposed individuals, assuming a dose rate effectiveness factor of 2 for cancers other than leukaemia. Leukaemias are seen as a wave from 5 to 30 years following exposure. Cancers other than leukaemia typically start to appear about 10 years following exposure and remain in excess for as long as most exposed populations are followed, presumably for the lifetime of the exposed individuals. The gonadal dose is so small from dental radiography that the risk of heritable defects is negligible in comparison with the somatic risk. The dental literature contains several studies reporting sufficient dosimetric data for radiosensitive sites in the head and neck to allow estimation of the risk of fatal cancers from intra-oral and panoramic radiography. The highest estimated risks (using the ICRP data) are for leukaemia (bone marrow), thyroid and bone surface cancer. The total risk is estimated to be 2.5 fatal malignancies per 10(6) full-mouth examinations made with D-speed film and round collimation.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Radiation-Induced↗
PubMed1992

Comparative means of dose reduction in dental radiography.

This review on dose reduction in dental radiography focuses on criteria for selecting the frequency and type of radiographs to be performed on patients. By making radiographs only when there is a reasonable probability of a finding that will influence patient care, patient exposure and other radiographic costs may be substantially reduced. Patient dose may also be reduced by half by changing from D-speed film to E-speed film for intraoral radiography and by more than half by changing from calcium tungstate intensifying screens to rare-earth intensifying screens for panoramic and cephalometric radiography. Using rectangular collimation for intraoral radiography will also further reduce patient exposure by about fourfold. Finally, the use of time-temperature processing will prevent overexposure of the patient and underprocessing of the radiographs; optimal radiographs will be provided.

Humans↗