Objectives: To develop image analysis software that can robustly and accurately measure the width... more Objectives: To develop image analysis software that can robustly and accurately measure the width of the inferior mandibular cortex on dental panoramic radiographs as an indicator of reduced bone mineral density (BMD). Methods: An Active Shape Model of the cortex was trained by expert annotation of 132 radiographs and used to locate the superior and inferior boundaries of the cortex automatically in a leave-one-out cross-validation test. Anatomical accuracy of the search is increased by employing a straightforward user interaction. Width was measured at 50 locations bilaterally between the antegonion and the mental foramen and averaged. Correlation between width and BMD (determined by DXA at the hip and spine) was measured and found to be highest in a region slightly medial to the antegonion – the “optimal” region. Taking osteopenia (T≤-1.0) as the categorical variable, we conducted ROC analysis using average width for both automatic and interactive search (tests 1 and 2) and “optimal” width (interactive search only – test 3). Results: Significant correlation (R=0.24, p<0.01) was found between BMD and average cortical width. ROC analysis gave Az values of 0.64, 0.66 and 0.71 in tests 1 2 and 3 respectively. Conclusions: We have developed an automatic image analysis method for measuring width of the inferior mandibular cortex. The average width between the antegonion and mental foramen correlates significantly with BMD. ROC analysis indicates that this method can contribute towards identification of osteopenia. The sensitivity and specificity of the measurement can be increased by the use of a straightforward user interaction. This work was supported by a research and technological development project grant from the European Commission FP5 'Quality of Life and Management of Living Resources' (QLK6-2002-02243)
Objectives: A previous study showed that the trabecular pattern on dental radiographs correlates ... more Objectives: A previous study showed that the trabecular pattern on dental radiographs correlates with femoral and spinal Bone Mineral Density (BMD). The objective of this study was to determine if the correlation is affected by size and location of the region of interest (ROI). Methods: In a European research project on osteoporosis BMD was measured at the left hip and the lumbar spine of 525 women. From all subjects intraoral radiographs were made of the premolar region in the upper and lower jaws. Two ROIs were indicated manually on each image and scanned. The smallest ROI involved trabecular bone only and the largest included parts of the neighbouring teeth as well. The ROIs were subjected to automatic image analysis yielding 26 measurements per ROI. Stepwise linear regression was used to predict femoral and spinal BMD. Results: Inner and outer regions predicted BMD equally well. Also the radiographs of lower and upper jaw predicted BMD equally well. Combining inner and outer regions did not improve the prediction of femoral and spinal BMD but combining lower and upper jaws did. Conclusions: This study shows that it is allowed to include parts of neighbouring teeth in the region of interest used to assess the trabecular pattern and predict BMD. This simplifies the process of selecting the ROI because no efforts have to be made to exclude neighbouring teeth. Combining ROIs of lower and upper jaws improves the prediction of BMD significantly.
Objective: In diagnostic imaging the human perception is the most prominent yet least studied sou... more Objective: In diagnostic imaging the human perception is the most prominent yet least studied source of error. Better understanding of image perception will help to improve diagnostic performance. This study focusses on the perception of coarseness of trabecular patterns on dental radiographs. Comparison of human vision with machine vision should yield knowledge on human perception. Material and Method: In a study on identifying osteoporotic patients dental radiographs were made from 505 postmenopausal women 45 to 70 years of age. Intraoral radiographs of the lower and upper jaws were made. Five observers graded the trabecular pattern in categories dense, sparse or mixed. The 5 gradings were combined into a single averaged observer score per jaw. The radiographs were scanned and a region of interest (ROI) was indicated on each. The ROI's were processed with image analysis software measuring 25 image features. Pearson correlation and multiple linear regression were used to compare the averaged observer score with the image features. Results: Fourteen image features correlated significantly with the observer judgement for both jaws. The strongest correlation was found for the average gray value in the ROI. Other features describing that osteoporotic patients have less but bigger marrow spaces than controls correlated less with the sparseness of the trabecular pattern than a rather crude measure for structure such as the average gray value. Conclusion: Human perception of the sparseness of trabecular patterns is based more on average gray value of the ROI than on geometric details within the ROI.
Key Words: oral health care workforce, emerging economies, education/training, national oral heal... more Key Words: oral health care workforce, emerging economies, education/training, national oral health care plan Health is a critical dimension of human well-being and flourishing; oral health is an integral component of health. One is not healthy without oral health. Significant barriers exist to ensuring the world’s people receive basic health care, including oral health care. Among the barriers are poverty, ignorance, inadequate financial resources, and lack of adequate numbers of educated and trained (oral) health care
To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bon... more To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bone mineral density of the edentulous mandible prior to implant placement. Ten 2 mm thick CT slices of anterior and posterior edentulous sections from 15 mandibles were obtained perpendicular to the buccal and lingual plates. The bone mineral density, expressed as the amount of calcium hydroxyapatite (mg cm-3) of the trabecular bone, was calculated using a method that takes into account the influence of fat. The variation of bone mineral density between mandibles was high. Anterior sections showed higher values than posterior sections and a variation was found within sections of the same mandible. CT provides a site-related measure of the bone mineral density in the mandible and appears potentially useful as a non-invasive method to determine a parameter that may reflect bone quality prior to implant placement.
The International journal of oral & maxillofacial implants, 1989
Panoramic radiography was compared with conventional tomography as techniques for visualizing the... more Panoramic radiography was compared with conventional tomography as techniques for visualizing the mandibular canal. Tomography gave a significantly clearer image of the canal at and 1 cm posterior to the mental foramen, while no differences were found between the methods 2 cm posterior to the mental foramen. Thus, tomography could be of great value in locating the mandibular canal before implant surgery in edentulous mandibular posterior segments.
European journal of dental education : official journal of the Association for Dental Education in Europe, Jan 16, 2014
To compare academic progress and performance of students admitted through two admission systems a... more To compare academic progress and performance of students admitted through two admission systems and to analyse the predictive power of different components in an alternative admission. The subjects were students admitted to the dental programme at Malmö University, Sweden. The grade admission group was admitted on grades from secondary school (n = 126) and the alternative admission group via an alternative admission procedure (n = 157). The alternative admission procedure consisted of the following components: problem-solving matrices, spatial capacity tested with folding and tin models, manual dexterity, capacity for empathy and interview. Comparisons were made for academic progress (dropouts from the programme and study rate) and academic performance (examinations failed and outcomes of a comprehensive clinical examination). Spearman correlation was calculated for each component of the alternative admission procedure and academic progress as well as academic performance. Multivari...
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2015
Children born prematurely often have reduced skeletal mineralization. The aim in this study was t... more Children born prematurely often have reduced skeletal mineralization. The aim in this study was to compare the cortical thickness of the lower jaw on radiographs of 8- to 10-year-old children with histories of preterm or full term births. There were no significant differences in cortical thickness between full term and preterm children at this age. The purpose of this study was to compare the cortical thickness of the mandible on panoramic radiographs of 8- to 10-year-old children with histories of preterm or full term births. Panoramic radiography was performed on 36 extremely preterm, 38 very preterm and 42 full term children at the age of 8 to 10 years. Five observers independently measured the mandibular cortical width on the panoramic radiographs at four defined sites bilaterally. Altogether, 928 sites were available. Measurements were performed twice on a random 24% of the sites by four observers. One-way analysis of variance with Tukey's post hoc test was used to test dif...
Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed)... more Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed), were compared regarding film fogging under different storage conditions. The films were stored during one year at room temperature (+21 degrees C) without shielding, with 3 mm lead or with 200 mm iron shielding and in a refrigerator (+8 degrees C) without shielding. The films were processed in a standardised way and the film fog measured densitometrically each month. The film fog increased insignificantly with time for both film types under all storage conditions except in the refrigerator, where it reached unacceptably high levels and the faster film type (Kodak Ektaspeed) became unusable after 4 months storage in the refrigerator.
The possibility to treat individuals with an edentulous maxilla with osseointegrated implants was... more The possibility to treat individuals with an edentulous maxilla with osseointegrated implants was studied in randomly selected individuals from the city of Malmö. From a panoramic radiograph one oral radiologist and one oral surgeon together decided possible number and length of implants potentially installable. It was found that treatment with osseointegrated implants could possibly be done in 80% of the individuals and in 20% bone transplantation would have been necessary. Preoperative tomography was needed in about two thirds of the individuals for a more accurate evaluation of the degree of bone resorption.
1School of Dentistry and 2Imaging Science and Biomedical Engineering, The University of Mancheste... more 1School of Dentistry and 2Imaging Science and Biomedical Engineering, The University of Manchester, United Kingdom 3School of Dentistry, Oral Pathology and Maxillofacial Surgery, Oral Imaging Centr ...
Objectives: The aim of this study was to investigate if the trabecular pattern in intraoral radio... more Objectives: The aim of this study was to investigate if the trabecular pattern in intraoral radiographs, assessed by five observers, could serve as an indicator of osteoporosis. Methods: Six hundre ...
2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Proceedings, 2007
We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic... more We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic tomograms (DPTs) which show the entire mandible. Careful expert width measurement of the inferior mandibular cortex has been shown to be predictive of BMD in hip and spine osteopenia and osteoporosis. We have implemented a method of automatic measurement of the width by active shape model search, using as training data 132 DPTs of female subjects and tested on a test data set of 606 DPTs of female subjects whose BMD has been established by dual-energy X-ray absorptiometry. We demonstrate that the sensitivity of the automatic method to osteoporosis is equivalent to that of expert manual measurement.
Objectives: To develop image analysis software that can robustly and accurately measure the width... more Objectives: To develop image analysis software that can robustly and accurately measure the width of the inferior mandibular cortex on dental panoramic radiographs as an indicator of reduced bone mineral density (BMD). Methods: An Active Shape Model of the cortex was trained by expert annotation of 132 radiographs and used to locate the superior and inferior boundaries of the cortex automatically in a leave-one-out cross-validation test. Anatomical accuracy of the search is increased by employing a straightforward user interaction. Width was measured at 50 locations bilaterally between the antegonion and the mental foramen and averaged. Correlation between width and BMD (determined by DXA at the hip and spine) was measured and found to be highest in a region slightly medial to the antegonion – the “optimal” region. Taking osteopenia (T≤-1.0) as the categorical variable, we conducted ROC analysis using average width for both automatic and interactive search (tests 1 and 2) and “optimal” width (interactive search only – test 3). Results: Significant correlation (R=0.24, p<0.01) was found between BMD and average cortical width. ROC analysis gave Az values of 0.64, 0.66 and 0.71 in tests 1 2 and 3 respectively. Conclusions: We have developed an automatic image analysis method for measuring width of the inferior mandibular cortex. The average width between the antegonion and mental foramen correlates significantly with BMD. ROC analysis indicates that this method can contribute towards identification of osteopenia. The sensitivity and specificity of the measurement can be increased by the use of a straightforward user interaction. This work was supported by a research and technological development project grant from the European Commission FP5 'Quality of Life and Management of Living Resources' (QLK6-2002-02243)
Objectives: A previous study showed that the trabecular pattern on dental radiographs correlates ... more Objectives: A previous study showed that the trabecular pattern on dental radiographs correlates with femoral and spinal Bone Mineral Density (BMD). The objective of this study was to determine if the correlation is affected by size and location of the region of interest (ROI). Methods: In a European research project on osteoporosis BMD was measured at the left hip and the lumbar spine of 525 women. From all subjects intraoral radiographs were made of the premolar region in the upper and lower jaws. Two ROIs were indicated manually on each image and scanned. The smallest ROI involved trabecular bone only and the largest included parts of the neighbouring teeth as well. The ROIs were subjected to automatic image analysis yielding 26 measurements per ROI. Stepwise linear regression was used to predict femoral and spinal BMD. Results: Inner and outer regions predicted BMD equally well. Also the radiographs of lower and upper jaw predicted BMD equally well. Combining inner and outer regions did not improve the prediction of femoral and spinal BMD but combining lower and upper jaws did. Conclusions: This study shows that it is allowed to include parts of neighbouring teeth in the region of interest used to assess the trabecular pattern and predict BMD. This simplifies the process of selecting the ROI because no efforts have to be made to exclude neighbouring teeth. Combining ROIs of lower and upper jaws improves the prediction of BMD significantly.
Objective: In diagnostic imaging the human perception is the most prominent yet least studied sou... more Objective: In diagnostic imaging the human perception is the most prominent yet least studied source of error. Better understanding of image perception will help to improve diagnostic performance. This study focusses on the perception of coarseness of trabecular patterns on dental radiographs. Comparison of human vision with machine vision should yield knowledge on human perception. Material and Method: In a study on identifying osteoporotic patients dental radiographs were made from 505 postmenopausal women 45 to 70 years of age. Intraoral radiographs of the lower and upper jaws were made. Five observers graded the trabecular pattern in categories dense, sparse or mixed. The 5 gradings were combined into a single averaged observer score per jaw. The radiographs were scanned and a region of interest (ROI) was indicated on each. The ROI's were processed with image analysis software measuring 25 image features. Pearson correlation and multiple linear regression were used to compare the averaged observer score with the image features. Results: Fourteen image features correlated significantly with the observer judgement for both jaws. The strongest correlation was found for the average gray value in the ROI. Other features describing that osteoporotic patients have less but bigger marrow spaces than controls correlated less with the sparseness of the trabecular pattern than a rather crude measure for structure such as the average gray value. Conclusion: Human perception of the sparseness of trabecular patterns is based more on average gray value of the ROI than on geometric details within the ROI.
Key Words: oral health care workforce, emerging economies, education/training, national oral heal... more Key Words: oral health care workforce, emerging economies, education/training, national oral health care plan Health is a critical dimension of human well-being and flourishing; oral health is an integral component of health. One is not healthy without oral health. Significant barriers exist to ensuring the world’s people receive basic health care, including oral health care. Among the barriers are poverty, ignorance, inadequate financial resources, and lack of adequate numbers of educated and trained (oral) health care
To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bon... more To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bone mineral density of the edentulous mandible prior to implant placement. Ten 2 mm thick CT slices of anterior and posterior edentulous sections from 15 mandibles were obtained perpendicular to the buccal and lingual plates. The bone mineral density, expressed as the amount of calcium hydroxyapatite (mg cm-3) of the trabecular bone, was calculated using a method that takes into account the influence of fat. The variation of bone mineral density between mandibles was high. Anterior sections showed higher values than posterior sections and a variation was found within sections of the same mandible. CT provides a site-related measure of the bone mineral density in the mandible and appears potentially useful as a non-invasive method to determine a parameter that may reflect bone quality prior to implant placement.
The International journal of oral & maxillofacial implants, 1989
Panoramic radiography was compared with conventional tomography as techniques for visualizing the... more Panoramic radiography was compared with conventional tomography as techniques for visualizing the mandibular canal. Tomography gave a significantly clearer image of the canal at and 1 cm posterior to the mental foramen, while no differences were found between the methods 2 cm posterior to the mental foramen. Thus, tomography could be of great value in locating the mandibular canal before implant surgery in edentulous mandibular posterior segments.
European journal of dental education : official journal of the Association for Dental Education in Europe, Jan 16, 2014
To compare academic progress and performance of students admitted through two admission systems a... more To compare academic progress and performance of students admitted through two admission systems and to analyse the predictive power of different components in an alternative admission. The subjects were students admitted to the dental programme at Malmö University, Sweden. The grade admission group was admitted on grades from secondary school (n = 126) and the alternative admission group via an alternative admission procedure (n = 157). The alternative admission procedure consisted of the following components: problem-solving matrices, spatial capacity tested with folding and tin models, manual dexterity, capacity for empathy and interview. Comparisons were made for academic progress (dropouts from the programme and study rate) and academic performance (examinations failed and outcomes of a comprehensive clinical examination). Spearman correlation was calculated for each component of the alternative admission procedure and academic progress as well as academic performance. Multivari...
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2015
Children born prematurely often have reduced skeletal mineralization. The aim in this study was t... more Children born prematurely often have reduced skeletal mineralization. The aim in this study was to compare the cortical thickness of the lower jaw on radiographs of 8- to 10-year-old children with histories of preterm or full term births. There were no significant differences in cortical thickness between full term and preterm children at this age. The purpose of this study was to compare the cortical thickness of the mandible on panoramic radiographs of 8- to 10-year-old children with histories of preterm or full term births. Panoramic radiography was performed on 36 extremely preterm, 38 very preterm and 42 full term children at the age of 8 to 10 years. Five observers independently measured the mandibular cortical width on the panoramic radiographs at four defined sites bilaterally. Altogether, 928 sites were available. Measurements were performed twice on a random 24% of the sites by four observers. One-way analysis of variance with Tukey's post hoc test was used to test dif...
Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed)... more Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed), were compared regarding film fogging under different storage conditions. The films were stored during one year at room temperature (+21 degrees C) without shielding, with 3 mm lead or with 200 mm iron shielding and in a refrigerator (+8 degrees C) without shielding. The films were processed in a standardised way and the film fog measured densitometrically each month. The film fog increased insignificantly with time for both film types under all storage conditions except in the refrigerator, where it reached unacceptably high levels and the faster film type (Kodak Ektaspeed) became unusable after 4 months storage in the refrigerator.
The possibility to treat individuals with an edentulous maxilla with osseointegrated implants was... more The possibility to treat individuals with an edentulous maxilla with osseointegrated implants was studied in randomly selected individuals from the city of Malmö. From a panoramic radiograph one oral radiologist and one oral surgeon together decided possible number and length of implants potentially installable. It was found that treatment with osseointegrated implants could possibly be done in 80% of the individuals and in 20% bone transplantation would have been necessary. Preoperative tomography was needed in about two thirds of the individuals for a more accurate evaluation of the degree of bone resorption.
1School of Dentistry and 2Imaging Science and Biomedical Engineering, The University of Mancheste... more 1School of Dentistry and 2Imaging Science and Biomedical Engineering, The University of Manchester, United Kingdom 3School of Dentistry, Oral Pathology and Maxillofacial Surgery, Oral Imaging Centr ...
Objectives: The aim of this study was to investigate if the trabecular pattern in intraoral radio... more Objectives: The aim of this study was to investigate if the trabecular pattern in intraoral radiographs, assessed by five observers, could serve as an indicator of osteoporosis. Methods: Six hundre ...
2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Proceedings, 2007
We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic... more We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic tomograms (DPTs) which show the entire mandible. Careful expert width measurement of the inferior mandibular cortex has been shown to be predictive of BMD in hip and spine osteopenia and osteoporosis. We have implemented a method of automatic measurement of the width by active shape model search, using as training data 132 DPTs of female subjects and tested on a test data set of 606 DPTs of female subjects whose BMD has been established by dual-energy X-ray absorptiometry. We demonstrate that the sensitivity of the automatic method to osteoporosis is equivalent to that of expert manual measurement.
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