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Biomedical subjects

G C H Sanderink

Publications and source records attributed to G C H Sanderink.

8 recordsLinked to original sources
PubMed2004

Looking for caries...? Teachers evaluate a program to improve caries diagnosis from radiographs.

We developed a computer-assisted learning (CAL) program to improve student caries diagnosis from bitewing radiographs. In order to decide on its appropriateness, dental teachers independently evaluated the program before it was introduced. Our objective was to describe an evaluation by the teachers of the CAL diagnostic module and to compare the diagnostic performance with the evaluation score of the program. Key dental teachers involved in teaching clinical caries diagnosis and epidemiology (n = 22) viewed the CAL program. They evaluated aspects of the program by scoring 10 criteria on a visual analogue scale. Measures of the teachers' initial diagnostic accuracy assessed during use of the program were: sensitivity and specificity for the presence of dentine caries. Using Pearson's correlation coefficients, these measures of the teachers' diagnostic accuracy were compared separately with their evaluation score of one aspect of the program: the overall functionality of the program for a 2nd-year dental student. The teachers' mean sensitivity for dentine caries diagnosis was 76.5% (median 77.8%; SD 15.4%) and the mean specificity was 93.7% (median 94.2%; SD 3.9%). The teachers gave the program a mean overall functionality score of 68% (median 75.1%; SD 21%). Dentists with a lower sensitivity (P = 0.065) for dentine caries tended to give the CAL program a higher overall functionality score than the other teachers. The CAL program was valued as generally useful. It tended to be more highly valued by the dentists with initially lower scores for diagnostic accuracy.

Computer-Assisted Instruction↗
PubMed2004

Evaluation of endodontic files in digital radiographs before and after employing three image processing algorithms.

OBJECTIVES: Two digital image processing algorithms, one aimed at correction for exponential attenuation and one at correction for visual response, have been developed. The aims of the present study were to test whether digital radiographs processed with these algorithms improve determination of the length of endodontic files and whether such processed radiographs are comparable with the radiographs processed with a default image processing method employed by one commercially available digital intraoral system. METHODS: A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower premolars and molars with endodontic files (Kerr files size 10 and size 15) positioned to the full length of the roots or 1.5 mm short of it. Radiographs were then processed in three sets. In one set, the radiographs were processed to compensate for exponential attenuation and the response of the human visual system. In the second, the radiographs were processed with the same compensation but with an additional shift in grey levels so that the output luminance in dentin at root tips corresponds to the mean of the luminance range of a computer monitor. In the third, the radiographs were processed with the default processing method in the Sidexis program. Ten viewers evaluated all radiographs. Receiver operating characteristic (ROC) curves were obtained and areas under the curves were calculated. RESULTS: For file size 10, ROC curves for processed radiographs were higher than that for originals, while for file size 15, ROC curves for processed and original radiographs were close to each other. Significant differences were found between processed and original radiographs regarding areas under ROC curves for file size 10 but not between the differently processed radiographs. For file size 15, no significant differences were found. CONCLUSION: Radiographs processed to correct for attenuation and visual response may improve determination of the length of thin endodontic files. Such processed radiographs are comparable with the radiographs processed with the default processing method in the Sidexis program.

Algorithms↗
PubMed2004

The dynamic range of digital radiographic systems: dose reduction or risk of overexposure?

OBJECTIVES: To investigate the range of diagnostically acceptable digital radiographs and film as a function of exposure time, as well as the relationship to dose reduction and consequences for dental practice. METHODS: Five systems for intraoral radiography were used to take a series of radiographs, with increasing exposure times, of five different dry bone specimens. Seven observers evaluated the 25 series of radiographs. The observers had to determine which radiographs of each series were acceptable for dental diagnostics and which radiograph of each series they preferred. RESULTS: For Ektaspeed Plus film, the exposure time for the preferred radiograph was 0.52 s, with a range of diagnostically acceptable radiographs from 0.23-1.02 s. The preferred radiograph of the solid-state systems required less radiation than film (Sirona, 0.13 s; MPDx 0.35 s). The exposure range of these systems is narrow. In contrast, the exposure range of the phosphor plate systems is very wide. The preferred radiograph of the phosphor plate systems required high exposure (Digora, 1.21 s; Gendex DenOptix, 1.16 s). CONCLUSIONS: All digital systems require less exposure than film for diagnostically acceptable radiographs, but this is less obvious for preferred radiographs. Solid-state systems alert the dentist when a too long exposure time is used by a lack of image quality; phosphor plate systems, however, produce good quality radiographs even at high exposure times, which may result in an unnecessarily high dose.

Analysis of Variance↗
PubMed2003

Randomized controlled trial of a computer-assisted learning program to improve caries detection from bitewing radiographs.

OBJECTIVES: To investigate whether using a computer-assisted learning (CAL) calibration program improves the accuracy of dental students in caries detection from bitewing radiographs. METHODS: Dental students were assigned to an experimental (n=33) and control (n=34) group using a randomized block design. The experimental group used the CAL program with feedback to calibrate themselves against experts in radiographic caries detection and a histological gold standard of the actual clinical condition. Feedback was provided visually of the actual tooth surface condition and in the form of graphics showing diagnostic accuracy performance measures. Performance was tested before the program (for the control group) and after the program (for the experimental group) by assessing surfaces (n=56) from a new independent digital test set of evaluation radiographs for the presence, histologically, of dentine caries (n=23). The summary receiver operating characteristic (SROC) method for summarizing true positive ratio (TPR) (sensitivity) and false positive ratio (FPR) (1-specificity) was used to analyse the dichotomous data. Differences between the control and experimental groups were tested for (a) the area under the SROC curve (A(z)) and (b) the TPR, FPR and diagnostic odds ratio (DOR) using the Mann-Whitney test (P<0.05). RESULTS: The mean TPR for dentine caries detection was 76.3% (SD 13.0%) for the experimental group and 66.9% (SD 14.8%) for the control group (P=0.005). Mean FPRs were similar (experimental 28.1% and control 28.7%; P>0.5). The area under the SROC curve A(z) was 0.832 for the experimental group and 0.773 for the control group (P=0.002). The mean DOR for dentine caries in the experimental group (12.4) was better than that in the control group (8.8) (P=0.003). CONCLUSIONS: The CAL program does improve diagnostic performance. Improving the cognitive feedback provided by the program should be considered before implementation.

Area Under Curve↗
PubMed2003

Does digital radiography increase the number of intraoral radiographs? A questionnaire study of Dutch dental practices.

OBJECTIVES: To compare the number of radiographs taken in general dental practices equipped with digital radiography vs conventional film-based radiography and to determine the reasons for any difference in numbers. METHODS: In a mail survey, 473 questionnaires were sent to Dutch General Dental Practitioners (GDPs) using digital radiography and 105 questionnaires were sent to GDPs using film. The questionnaire concerned the number of intraoral radiographs taken in the dental practice, as well as possible reasons to take more or fewer radiographs after conversion to digital radiography. RESULTS: The response rate was 73%. Users of a phosphor plate system on average take 42.8 radiographs per week and solid-state system users take 48.4 radiographs, whereas film users take on average only 32.5 radiographs per week. The need for more certainty about the planned or ongoing treatment as well as better diagnostics were the most important reasons for taking more radiographs. CONCLUSIONS: It seems that GDPs using a system for digital radiography are more inclined to take radiographs than dentists taking conventional radiographs. Although digital intraoral radiography requires 50-80% less radiation per exposure than film, it is likely that the effective dose reduction after converting from conventional to digital radiography is less than 25% owing to the greater numbers of radiographs taken.

Attitude of Health Personnel↗
PubMed2002

A comparison of digital and film radiography in Dutch dental practices assessed by questionnaire.

OBJECTIVES: The purpose of this study was to assess the experiences of general dental practitioners (GDPs) with solid-state and storage phosphor digital sensors compared to film. METHODS: In a mail survey 578 questionnaires were sent to Dutch GDPs who were users of digital X-ray detectors and film. The questionnaire requested demographic data, information about the digital system used and the user-friendliness of the X-ray detector system. In the analysis of the data these variables were related to the type of system used and also to the demographic data. The data were analysed using descriptive statistics, variance-analysis (One-Way ANOVA) and nonparametric tests (Kruskal-Wallis, Mann-Whitney and Wilcoxon) (SPSS 9.0). RESULTS: Four hundred and twenty-four questionnaires were returned (overall response rate 73%). The user-friendliness of the handling of the different systems before exposing the radiograph is better for conventional film, whereas the handling after exposing the radiograph favoured the digital X-ray detector systems. CONCLUSIONS: The user-friendliness was best for film pre-exposure and digital sensors post-exposure.

Adult↗
PubMed2002

A comparison of two compression algorithms and the detection of caries.

OBJECTIVES: To assess the effect of two compression algorithms (JPEG and wavelet) on the detection of approximal caries. METHODS: Fifteen bitewing radiographs were generated using 100 posterior teeth mounted in blocks. The images were produced on conventional films (Ektaspeed Plus) and scanned at 300 d.p.i. Digital images were then compressed 9:1 with JPEG and wavelet methods. Nine observers detected the presence and depth of approximal caries recorded on a 5-point confidence scale and a 4-point depth scale from images viewed in random order. Histological examination provided the true depth of the lesions. Data were analysed by means of ANOVA. The null hypothesis was that there is no significant difference between the two compression algorithms and the original uncompressed images. RESULTS: JPEG performed significantly worse than the original and the wavelet algorithm (P<0.001) for the detection of dentinal lesions. However, no significant differences were found for the detection of sound surfaces, enamel lesions, and lesions up to the DEJ between JPEG-compressed images and each of the other two modalities. There was also no significant difference between the wavelet-compressed images and the original for all lesion depths. CONCLUSIONS: At a compression ratio of 9:1, there were no significant differences among the original images, JPEG and wavelet compressed images for the detection of enamel caries. JPEG-compressed images performed inferiorly to the original and wavelet-compressed images for the detection of dentinal lesions. Wavelet compression is a better choice than JPEG at the compression ratio investigated in this study.

Algorithms↗