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Biomedical subjects

André Mol

Publications and source records attributed to André Mol.

6 recordsLinked to original sources
PubMed2006

In vitro assessment of cone beam local computed tomography for proximal caries detection.

OBJECTIVES: To compare the accuracy of local computed tomography (LCT) and conventional radiography for proximal caries detection and depth assessment. STUDY DESIGN: An in vitro model was used consisting of 20 extracted posterior teeth with 18 caries lesions. Local computed tomography slices were reconstructed in axial and parasagittal planes from 100 basis projections. Conventional radiographs were also acquired. Eight observers determined the presence and depth of caries lesions. Receiver operating characteristic analysis and weighted kappa statistics were used. RESULTS: Local computed tomography had a mean A(z) score of 0.82 (SD = 0.07) and conventional radiography of 0.79 (SD = 0.08; analysis of variance: P > .05). Interobserver agreement was moderate. The mean kappa for depth assessment was 0.68 (SD = 0.06) for LCT and 0.47 (SD = 0.08) for conventional radiography (analysis of variance: P < .05). Local computed tomography resulted in substantial and conventional radiography in moderate interobserver agreement. CONCLUSIONS: There is no difference between LCT and conventional radiography for proximal caries detection. Local computed tomography was more accurate for assessing caries lesion depth.

Adult↗
PubMed2006

In vitro assessment of local computed tomography for the detection of longitudinal tooth fractures.

OBJECTIVE: To test the accuracy of local computed tomography (LCT) in detecting longitudinal fractures in comparison with conventional periapical radiographs. STUDY DESIGN: Longitudinal fractures were induced in 30 of 60 teeth. The teeth were placed in a dry dentate mandible with soft tissue simulation. A laboratory LCT unit was used to acquire 180 basis projections with 1 degree separation along a 180 degree arc. Conventional radiographs served as the control modality. Correlated axial, coronal, and sagittal views were presented to 10 observers. The observers determined the presence of a root fracture by using a 5-point receiver operating characteristic confidence scale. RESULTS: The mean A(z) for LCT was 0.91 (SD = 0.07). The mean A(z) for conventional radiography was 0.70 (SD = 0.07). The difference between the modalities was statistically significant (analysis of variance: P < .0002), whereas the differences between the observers was not (analysis of variance: P = .319). CONCLUSION: Local CT significantly improves the detection of longitudinal fractures in vitro compared with conventional periapical radiography.

Analysis of Variance↗
PubMed2003

The performance of projective standardization for digital subtraction radiography.

OBJECTIVE: We sought to test the performance and robustness of projective standardization in preserving invariant properties of subtraction images in the presence of irreversible projection errors. Study design Twenty bone chips (1-10 mg each) were placed on dentate dry mandibles. Follow-up images were obtained without the bone chips, and irreversible projection errors of up to 6 degrees were introduced. Digitized image intensities were normalized, and follow-up images were geometrically reconstructed by 2 operators using anatomical and fiduciary landmarks. Subtraction images were analyzed by 3 observers. RESULTS: Regression analysis revealed a linear relationship between radiographic estimates of mineral loss and actual mineral loss (R(2) = 0.99; P <.05). The effect of projection error was not significant (general linear model [GLM]: P >.05). There was no difference between the radiographic estimates from images standardized with anatomical landmarks and those standardized with fiduciary landmarks (Wilcoxon signed rank test: P >.05). Operator variability was low for image analysis alone (R(2) = 0.99; P <.05), as well as for the entire procedure (R(2) = 0.98; P <.05). The predicted detection limit was smaller than 1 mg. CONCLUSIONS: Subtraction images registered by projective standardization yield estimates of osseous change that are invariant to irreversible projection errors of up to 6 degrees. Within these limits, operator precision is high and anatomical landmarks can be used to establish correspondence.

Algorithms↗
PubMed2003

Effect of bone chip orientation on quantitative estimates of changes in bone mass using digital subtraction radiography.

OBJECTIVES: To assess the effect of the orientation of arbitrarily shaped bone chips on the correlation between radiographic estimates of bone loss and true mineral loss using digital subtraction radiography. METHODS: Twenty arbitrarily shaped bone chips (dry weight 1-10 mg) were placed individually on the superior lingual aspect of the interdental alveolar bone of a dry dentate hemi-mandible. After acquiring the first baseline image, each chip was rotated 90 degrees and a second radiograph was captured. Follow-up images were created without the bone chips and after rotating the mandible 0, 1, 2, 4, and 6 degrees around a vertical axis. Aluminum step tablet intensities were used to normalize image intensities for each image pair. Follow-up images were registered and geometrically standardized using projective standardization. Bone chips were dry ashed and analyzed for calcium content using atomic absorption. RESULTS: No significant difference was found between the radiographic estimates of bone loss from the different bone chip orientations (Wilcoxon: P > 0.05). The correlation between the two series of estimates for all rotations was 0.93 (Spearman: P < 0.05). Linear regression analysis indicated that both correlates did not differ appreciably ( and ). CONCLUSION: It is concluded that the spatial orientation of arbitrarily shaped bone chips does not have a significant impact on quantitative estimates of changes in bone mass in digital subtraction radiography. These results were obtained in the presence of irreversible projection errors of up to six degrees and after application of projective standardization for image reconstruction and image registration.

Alveolar Process↗