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Biomedical subjects

Ssu-Kuang Chen

Publications and source records attributed to Ssu-Kuang Chen.

8 recordsLinked to original sources
PubMed2005

Digital imaging analysis with mathematical morphology and fractal dimension for evaluation of periapical lesions following endodontic treatment.

OBJECTIVE: To see if a method for digitizing trabecular pattern of bone could be used to quantitatively evaluate changes in bone pattern following endodontic treatment of teeth with periapical osteolytic lesions. STUDY DESIGN: Periapical radiographs were digitized and further processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension analysis using box-counting. RESULTS: The periapical area in digitized radiographic images showed fractal behavior. Twenty-five of 27 patients showed increase of the fractal dimension after root canal treatment. Significant changes of the box-counting could be noted 3 months after root canal treatment (P < .05). CONCLUSIONS: Mathematical morphology operation and box-counting might be helpful in early detection of changes of periapical trabecular pattern after root canal treatment.

Adult↗
PubMed2005

A pilot study applying digital radiography for estimating ratio of supported single-root surface area.

BACKGROUND: The prognosis of a tooth with periodontitis is affected by the amount of supporting bone. A key factor in retaining a tooth is the ratio of supported root surface. Currently, root surfaces cannot be accurately measured using conventional dental radiographs, which only measure the length of bone support on proximal surfaces. METHODS: Eight extracted, single-rooted teeth were 3-dimensionally digitized using a contact technique for true surface area measurements. Root length, projection area, and pixel values were then measured on digital radiographs. The accuracy of the ratio estimation of supported surface area from linear, area, and pixel values was calculated and compared. RESULTS: The mean error from linear estimation was 7.9%; the mean error from area estimation was 1.0%; and the mean error from pixel value estimation was 1.3%. One-way analysis of variance (ANOVA) showed significant differences in all estimations while Scheffé's analysis further revealed significant differences only in the linear estimation. CONCLUSIONS: A three-dimensional digitizing device could be used as a non-destructive method of measuring root surface area. The ratio of supported single-root surface area could be estimated with high accuracy from the projected area data acquired on the digital dental radiographs. The thickness data as reflected from the pixel values in the digital images did not improve the estimation accuracy. Estimations using only length data yielded significantly less accuracy. Digital dental x-ray images provide the potential for estimating the ratio of supported root surface efficiently.

Analysis of Variance↗
PubMed2004

The effects of differences in landmark identification on the cephalometric measurements in traditional versus digitized cephalometry.

The aim of this study was to explore the effects of differences in landmark identification on the values of cephalometric measurements on digitized cephalograms in comparison with those obtained from original radiographs. Ten cephalometric radiographs were randomly selected from orthodontic patients' records. Seven orthodontic residents identified 19 cephalometric landmarks on the original radiographs and digitized images. Twenty-seven cephalometric measurements were computed with a customized computer-aided program. To assess the concordance between cephalometric measurements derived from landmarks identified on the original radiographs and those from digitized counterparts, the values of 27 cephalometric measurements were compared to quantify the absolute value of measurement difference and the interobserver errors between these two methods. We found that the differences of all cephalometric measurements between original radiographs and their digitized counterparts were statistically significant. The differences in 21 of the 27 cephalometric items were less than two units of measurement (mm or degree), which is generally within one standard deviation of norm values in conventional cephalometric analysis. Moreover, statistically significant differences of interobserver errors between the two methods were noted only for seven of the 27 cephalometric items. In conclusion, the measurement differences between the original cephalograms and the digitized images are statistically significant but clinically acceptable. The interobserver errors for cephalometric measurements on our digitized cephalometric images are generally comparable with those on the original radiographs. The results of our study substantiated the benefits of digital cephalometry in terms of the reliability of cephalometric analysis.

Cephalometry↗
PubMed2004

Enhanced speed and precision of measurement in a computer-assisted digital cephalometric analysis system.

The computer-assisted digital cephalometric analysis system (CADCAS) may reduce the time required for cephalometric analysis, especially for taking measurements. Aimed at estimating the time saved by using CADCAS, we measured the time needed by a clinician to perform the analysis in a traditional manner. We also sought to verify the accuracy achieved by traditional cephalometric analysis by exploring the disagreement between manual measurements and those generated by CADCAS. Our results revealed that, on average, even an experienced clinician needed more than 25 minutes to perform an entire cephalometric analysis using a traditional method, with more than 15 minutes of this needed just for taking measurements. Disagreements between measurements by traditional method and those by CADCAS were most frequently noted in the measurement value of cephalometric items reflecting the severity of a jaw discrepancy by the "sign" reflecting the anteroposterior relationship. After excluding the measurements with obvious error, the measurement differences between traditional method and CADCAS were not statistically significant in 23 of a total of 26 cephalometric items. In conclusion, the CADCAS can reduce the time needed for cephalometric analysis and can help reduce the human errors introduced during the manual-measuring procedure in the traditional cephalometric analysis.

Cephalometry↗
PubMed2004

Accuracy of supported root ratio estimation from projected length and area using digital radiographs.

BACKGROUND: The purpose of this study was to evaluate the accuracy of supported single-root surface ratio estimated from the length and projected area of the tooth, using digital dental radiographs. METHODS: Eight extracted, single-root teeth were three-dimensionally digitized using a contact technique for surface area measurement. The data were then processed using engineering application software and length, projection area, and true surface area of the root at a designated length were obtained. Based on these three measurements, the accuracy of the supported surface area ratio measurement at different lengths of the root was evaluated. RESULTS: The largest mean errors from linear and area estimation were 9.58% and -1.16%, respectively. The 95% confidence intervals were all positive, indicating that linear measurements overestimated supported ratio. T tests showed that linear estimations resulted in significant differences in all eight teeth and area estimations in five teeth. When analyzing the supported ratio of the alveolar bone receding from the cemento-enamel junction (CEJ) toward the apex of the root at each mm, linear estimation showed significant differences down to 8 mm, while area estimation showed significant differences only up to 2 mm. CONCLUSIONS: The results of this study indicate that a reliable estimate of the ratio of root surface area supported by alveolar bone cannot be determined from linear or area data. However, when the marginal bone destruction exceeds 2 mm from the CEJ, area estimation does not show a significant difference in the supported region. As demonstrated in this study, root surface ratio estimation function could be an advantage of digital dental x-ray systems in which projected root area is readily observed.

Alveolar Process↗
PubMed2002

Calculation of simplified single-root surface area from simulated X-ray projection.

BACKGROUND: The prognosis of a tooth affected by periodontitis might depend on the amount of bone remaining around the root surface. The surface area of a single tooth root relates to a simulated x-ray projection. METHODS: The aim of the study was to determine root surface area from radiographs. Two methods were used. In the first, cross-sections of a single-tooth root were simulated using ellipses with different eccentricities. Projection data from 90 directions at 1 degrees intervals were obtained, which were then used to estimate circumferences that were then compared with the known circumference. In the second model, circumference was estimated from projection data derived from the projection of an ellipse with the central ray parallel to the long axis. The estimated circumference was compared with possible circumferences resulting from this projection data. RESULTS: In the first model, all estimated circumferences are less than the true circumferences. The largest error in each case decreased rapidly as the eccentricity of the simulated ellipse decreased. Less than 6% of the largest errors were found when the eccentricity is 0.83. In the second model, the estimation should be within less than 2% of error when the asymmetry factor is less than 0.6. CONCLUSIONS: The circumference of an elliptical object can be approximated from the projection data of this ellipse. Therefore, the surface area of a single tooth root may be estimated with clinically useful accuracy from the projection data.

Algorithms↗