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Biomedical subjects

T J Heaven

Publications and source records attributed to T J Heaven.

16 recordsLinked to original sources
PubMed1999

The effect of multiple examinations on the diagnosis of approximal caries and the restoration of approximal surfaces.

OBJECTIVE: The aim of this study was to determine the effect of multiple examinations on sensitivity and specificity in the diagnosis and restoration of approximal caries. STUDY DESIGN: In 2 studies, dentists examined bitewing radiographic films for approximal caries and the need for restoration. To model the clinical situation of multiple examinations over time, all groups of combinations of 2 to 10 dentists were constructed. Mean sensitivity and specificity were determined. In addition, 2 new variables were created: the first, "sensitivity any," was calculated by assigning a correct diagnosis for disease if any dentist in the group identified the diseased surface correctly; the second, "specificity all," was calculated by assigning a correct response only when all dentists in the group correctly identify a nondiseased surface. RESULTS: The sensitivity and specificity means were the same for all group sizes. The "sensitivity any" means increased monotonically from group size 1 to group size 10, whereas the "specificity all" means decreased continually. There was a statistically significant difference between sensitivity and "sensitivity any" and between specificity and "specificity all" for all group sizes in both studies. CONCLUSIONS: Multiple examinations increase the number of carious surfaces correctly diagnosed and the number of surfaces appropriately restored; however, multiple examinations also increase the number of sound surfaces diagnosed as carious and the number of intact surfaces receiving restorations.

Decision Making↗
PubMed1998

The effect of a knowledge-based, image analysis and clinical decision support system on observer performance in the diagnosis of approximal caries from radiographic images.

The aim of this study was to investigate the effect of a knowledge-based image analysis and clinical decision support system (CariesFinder, CF) on diagnostic performance and therapeutic decisions. The study material consisted of radiographic images of 102 approximal surfaces, 35 sound, 67 caries (25 caries and cavitated and 42 caries). Sixteen general practitioners were presented with (1) radiographic film images and (2) digital filmless images with the results of CF. The viewers were asked to respond whether approximal caries was present and whether a restoration was indicated. Responses were analyzed for accuracy, sensitivity, specificity and agreement. Further, the practitioners were ranked according to the accuracy of their restorative decisions and assigned to ten overlapping groups of 7 practitioners. For each group the diagnostic and therapeutic decisions were then examined for unanimity. The parameters of accuracy, sensitivity and specificity were then established for each group based on only unanimous, correct decisions. The diagnostic and therapeutic accuracy of CF alone was equal or superior to the decisions of the practitioners viewing film images alone. For unanimous decisions, CF alone was more accurate than the most accurate group of practitioners and made fewer incorrect decisions to restore non-cavitated surfaces than the practitioners. In general, dental practitioners viewing the results of CF significantly increased their ability to diagnose caries correctly, their overall diagnostic accuracy, and their ability to recommend restorations for cavitated surfaces. There was a decrease in the accuracy of their restorative decisions overall and in the specificity in particular.

Analysis of Variance↗
PubMed1997

Evaluation of video imaging prediction in combined maxillary and mandibular orthognathic surgery.

The purpose of this study was to evaluate the accuracy of the soft tissue profile "line drawings" predicted by Quick Ceph Image in combined maxillary and mandibular orthognathic surgical procedures. Preoperative (mean = 27.7 days presurgical) and posttreatment (mean = 11.5 months postsurgical) lateral cephalograms of 40 white patients (10 males and 30 females) who had completed treatment that involved orthodontics, one-piece LeFort I osteotomy, and mandibular advancement by bilateral sagittal split osteotomy with or without genioplasty were used in the study. Forty-five lateral hard and soft tissue landmarks were digitized, using the "on-screen" digitizing option, for each cephalogram and for each computer predicted posttreatment tracing. A customized analysis consisting of 24 linear and 4 angular measurements was used to analyze the differences between the actual posttreatment cephalometric landmark measurements and computer predicted landmark measurements. Statistically significant differences between the posttreatment cephalometric soft tissue profiles and the computer predicted soft tissue profiles were analyzed for the total sample, patients grouped according to: magnitude and direction of maxillary movements, adjunctive genioplasty procedure, V-Y closure of the LeFort I incision, and gender and age differences. The results indicated that for some of the soft tissue landmarks, differences were found between the posttreatment and the computer predicted profiles. Differences between the predicted and actual posttreatment soft tissue profiles may be attributed to the inaccuracy of Quick Ceph Image's default soft to hard tissue ratios when predicting the soft tissue response to combined maxillary and mandibular orthognathic surgical procedures.

Adolescent↗
PubMed1995

Radiographic evaluation of occlusal caries: effect of training and experience.

The purpose of this study was to investigate what effect differing levels of didactic education and clinical experience have on the ability to diagnose occlusal caries from radiographs. Freshman and senior dental students and dental school faculty were asked to evaluate bitewing radiographs for the presence of occlusal caries and for a recommendation for restorative treatment. The agreement between histologic and radiographic diagnosis was assessed by calculating sensitivity, specificity, accuracy, and interexaminer agreement. It was concluded that dental students and faculty did differ in their abilities to evaluate radiographs for occlusal caries, and that education and clinical experience especially affected interexaminer agreement.

Clinical Competence↗
PubMed1994

Air-rotor stripping and enamel demineralization in vitro.

This investigation sought to evaluate the effects of air-rotor stripping on the susceptibility of human enamel to demineralization using an in vitro caries model. Crowns of extracted premolar teeth were abraded (0.5 mm) on one proximal surface by air-rotor stripping. The teeth were placed in a demineralizing gel and removed at various intervals up to 336 hours. Lesion depth and mineral content on the abraded and intact surfaces was measured with contact microradiography and computerized image analysis (double window technique). For each time interval measured, lesion depth was greater (p < 0.05) on the abraded surfaces and mineral density was significantly less (p < 0.05). In a second experiment, the effect of fluoride supplements (dentifrice or topical gel) were examined on abraded and intact enamel surfaces that were exposed to the acid gel for 192 hours. The data showed that fluoride treatments significantly reduced lesion penetration on intact and abraded surfaces compared with a no fluoride group. Lesion depth on the abraded, fluoride treated surfaces was significantly greater (p < 0.05) than on the intact untreated surfaces. No significant differences (p < 0.05) were apparent between the fluoride treatment groups with respect to lesion depth and mineral density within the lesion. These results suggest that air-rotor stripping significantly increases the susceptibility of proximal enamel surfaces to demineralization. As a result, the clinician should use caution in the application of this technique until the long-term effects on caries susceptibility have been determined.

Acidulated Phosphate Fluoride↗
PubMed1994

The use of a computer-based image analysis program for the diagnosis of approximal caries from bitewing radiographs.

Approximal surfaces of 13 extracted molar and premolar teeth were classified directly and radiographically as sound or decayed. Eleven faculty dentists examined bitewing radiographs of the teeth and responded on a 5-point certainty scale, whether caries was present. Ten other faculty dentists used a computer-based program to examine the radiographs. For sensitivity, area under the receiver operating characteristic curve, and interexaminer agreement (Kappa), the computer-assisted faculty was significantly (p < 0.05) superior or equal to the unassisted faculty group.

Bicuspid↗
PubMed1994

The effect of experience and training on the diagnosis of approximal coronal caries from bitewing radiographs. A Swiss-American comparison.

The purpose of the present study was to compare the development of skills in the radiographic diagnosis of approximal coronal caries. Swiss (Bern) and American (Alabama) dental students with and without clinical experience, Swiss general practitioners, and Swiss and American dental school faculty viewed bitewing radiographic films of 13 teeth. The observers examined the 26 approximal surfaces on the radiographic films and responded, on a five point certainty scale, whether approximal caries was present. Mean sensitivity ranged from a low of 0.59 for American faculty to a high of 0.80 for Swiss students with clinical experience, mean specificity ranged from 0.84 for Swiss pre-clinical students to 0.95 for American faculty. For a summary measure of accuracy, i.e., area under the receiver operating characteristic (ROC) curve, the scores for student observers tended to increase with experience. The scores for Swiss and American students with clinical experience and faculty did not differ significantly. Inter-examiner agreement (Kappa) could only be characterized as moderate at best. Formal didactic instruction and clinical experience produced dental students with skills in the diagnosis of approximal caries from bitewing radiographs similar to that of faculty dentists.

Alabama↗
PubMed1994

Shear bond strengths of composite to chlorhexidine-treated enamel.

This study determined the shear bond strength (SBS) of composite bonded to chlorhexidine-treated enamel and untreated enamel. Fifty human molars were mounted in cold- cure acrylic and the superficial enamel of the buccal or lingual surface was exposed using 600-grit silicon carbide paper. During the experimental protocol, the control group (n = 25) and the experimental group (n = 25) were stored in distilled water at 37 degrees C. The experimental group was immersed in 0.12% chlorhexidine gluconate for 1 minute, 4 times daily, for 7 days. Prisma APH composite was then bonded to all samples following acid etching for 30 seconds, and the SBS was determined. Shear bond strengths for the control (13.23 +/- 3.22 MPa) and the experimental (13.67 +/- 4.59 MPa) groups were not significantly different using a t-test. The result may be attributed to either a lack of effect of chlorhexidine or to the acid etch which dissolves the affected superficial enamel leaving an unaffected substrate for bonding.

Acid Etching, Dental↗
PubMed1993

In vitro demineralization by strains of Actinomyces viscosus and Streptococcus sobrinus of sound and demineralized root surfaces.

Root sections were inoculated with one of two strains of Actinomyces viscosus or a strain of Streptococcus sobrinus and then incubated for 9 days in Trypticase soy broth (TSB) containing 0.25% glucose or TSB supplemented with 0.25% sucrose (TSB+S). Lesion progression was measured from microradiographs. One section from each group was examined with a transmission electron microscope. Lesion progression was associated with a fall in the pH of the medium. However, lesion progression was not correlated with the mean 48-hour pH of the medium. In both TSB and TSB + S, lesion progression with A. viscosus was significantly greater than in the S. sobrinus group. However, the mean 48-hour pH value in TSB + S was lower than that in the S. sobrinus group. Plaque formation in TSB was, subjectively, least in the S. sobrinus group. Examination of transmission electron micrographs revealed bacteria penetrating the surfaces of the sections and extending into the lesion in the A. viscosus groups but not in the S. sobrinus group. This in vitro bacterial plaque model of root caries may be suitable for investigations of the bacterial etiology of root-surface caries and the virulence factors associated with pathogenicity.

Actinomyces viscosus↗
PubMed1992

Computer-based image analysis of natural approximal caries on radiographic films.

This paper reports on the development of computer software for automatic detection and measurement of approximal caries lesions on digital images obtained from radiographic films. If the program detects a lesion, it defines the lesion's border and measures and reports these lesion parameters: percent mineralization, area, maximum enamel penetration, and mean enamel penetration. Two experiments are reported; both were conducted with the use of extracted human premolar teeth. In the first experiment, thin sections were obtained from 13 approximal surfaces with caries lesions. Microradiographs were made of the sections, and software measurements of the lesions were obtained from the microradiographs. The software was able to separate the lesions into two groups: those that had penetrated less than 100% of the enamel and those that had penetrated 100% of the enamel. The software measurements agreed with evaluation of lesion penetration by polarized light microscopy of the thin sections. In the second experiment, simulated clinical radiographs were made of 16 approximal surfaces, 12 with lesions and four without. Thin sections were obtained for microradiography. Software was used for automatic detection and measurement of the lesions on both types of film. The ability of the software to detect the lesions on the clinical films was compared with that of 10 experienced clinicians. Correlations of the same parameter from the two types of radiographic films were statistically significant, 0.86 less than or equal to r less than or equal to 0.95 and p less than 0.05. The coefficients of variation were low for both microradiographs, 0.4-2.3%, and for clinical films, 0.7-8.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

Calibration errors in digital subtraction radiography.

Two methods for the measurements of osseous change detected by digital subtraction radiography have been evaluated. Estimates of errors introduced by soft and hard tissues that overlay the region of interest (ROI) or by soft tissue that replaced the bone are made. All estimates are made assuming that the radiation source is a 40 keV monoenergetic beam and the reference standard is equivalent to compact bone. These assumptions facilitate a theoretical analysis of calibration errors on a relative scale. The radiographic image method uses a calibration wedge on each of the two films. The mean gray value of the ROI on each film is converted into an equivalent thickness of bone by matching the ROI mean gray value to a gray value along the wedge. These thickness values are then subtracted to obtain a measurement of the amount of change. The subtraction image method makes use of a wedge on only one of the two films. The image of the subtraction of the two radiographs is used for detection of the area of change and the mean gray value of the ROI is matched to a gray value along the wedge. The thickness of the wedge at this point is the measured change. The errors introduced by inclusion of the cheek over the ROI and the replacement of bone by soft tissue are estimated for the radiographic image method. The influence of unequal beam attenuation between the reference ramp and the ROI is estimated for the subtraction image method. Other factors influencing the accuracy of estimates of osseous change which are nonlinear in their effects are also considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Calibration↗
PubMed1990

Quantitative radiographic measurement of dentinal lesions.

The purpose of this investigation was the comparison of the precision and accuracy of two reference ramp techniques for the quantification of radiographic density changes in teeth. Radiographs (65 kVp, 10 ma, 1 s, and intra-oral ultraspeed film) of transverse sections from extracted permanent human molars were made before and after dentinal lesions were created. Each radiograph contained the image of a tooth section and the aluminum reference ramp. Method A used the image of the ramp on both the before- and after-lesion radiographs, and method B used the image of the ramp only on the before-lesion radiograph. Three groups of lesions (0.525-mm diameter, n = 11; 0.675-mm diameter, n = 9; and the 0.525-mm holes enlarged to 0.675 mm) were measured radiographically by each technique and by direct planimetry of the lesions. Radiographic method B produced results in close agreement with the planimetric measurements. Method B differentiated (p less than 0.05) between groups that had a mean planimetric size difference of 0.10 mm (equivalent to a change in density difference of 0.6%). These density change measurements are in absolute units of mm of aluminum that can be compared between lesions and between samples. This technique may prove useful for the quantification of changes in mineral density of caries lesions detectable in longitudinal radiographic records.

Dental Caries↗
PubMedDate not supplied

In vitro dentine fluoride uptake from three fluoride-containing composites and their acid resistance.

OBJECTIVES: The purpose of this study was to determine the dentine fluoride uptake from three fluoride-containing composites (FluorEver, FluoroCore and Pertac-Hybrid) and to investigate their ability to affect the resistance of dentine to an artificial caries challenge. METHODS: Three dentine slabs were prepared from each tooth. The baseline, total and bound fluoride concentrations of each tooth were determined by three successive abrasion biopsies performed on each slab followed by adjusting to standardized depths of 10 microns. Next, dentine slabs ligated with the composites were suspended in synthetic saliva for 1 week. After removal of the composites, these specimens and controls were immersed in an artificial caries medium (pH 4.5) for 5 days. Each slab was sectioned and analysed by quantitative microradiography. RESULTS: The results indicate that dentine acquired significantly different amounts of fluoride from the three composites. The acid resistance of dentine in contact with the composites was also significantly different among the composites and followed the same order as for fluoride uptake. CONCLUSIONS: Dentine fluoride uptake and artificial caries inhibition were significantly greater with FluorEver followed by FluoroCore and Pertac-Hybrid.

Biopsy↗