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Storage phosphor plates: how durable are they as a digital dental radiographic system?
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 97, Number 2 explainable as well from a genetic point of view. Another syndrome, Tricho-odonto-onychial dysplasia, is manifested by severe dystrophic changes in nails and secondary anodontia. Owing to its rarity, the genetic background of this condition is yet to be discovered. Whether these 2 conditions originate from differential expression of the same mutated gene remains to be clarified.
EARLY DETECTION AND QUANTITATIVE ASSESSMENT OF APICAL ROOT RESORPTION USING CROWNROOT RATIO AND TUNED-APERTURE COMPUTED TOMOGRAPHY (TACT). Andre´ Mol, Julie H. Mol, Onanong Chai-u-dom, and Donald A. Tyndall, University of North Carolina, Chapel Hill, NC, and Chulalongkorn University, Bangkok, Thailand Background. Apical root resorption (ARR) is a complication of orthodontic treatment without clear causative factors. The relationship between causative factors and ARR may be obscured by inaccuracies in current methods of detection and quantification. Twodimensional imaging, lack of image standardization, as well as orthodontic tooth movement and remodeling of the surrounding tissues all pose considerable challenges. Objective. The purpose of this study was to develop and test a tuned-aperture computed tomography (TACT) application and to assess the validity of the crown-root ratio (CRR) method for the detection and quantification of small oblique apical root resorption lesions. Methods and materials. A registered (R) and a nonregistered (NR) version of TACT were tested. In TACT-R, the detector moved with the tooth through mechanical standardization. TACT-NR allowed the tooth to move independently of the detector. Ten basis images with a maximum angular disparity of 20° were used. Oblique slicing of TACT-NR follow-up stacks was required for registration with baseline stacks. A slice shifting algorithm was applied to prevent drifting of cross-talk shadows. Twenty extracted maxillary incisors placed in a widened alveolus of a maxillary jaw segment served as test and control sites. Baseline images were acquired without lesions. Follow-up images were acquired with and without lesions. Lesions were created by cutting an oblique buccolingual segment of the root just below the apex. Teeth were moved between baseline and follow-up (rotation and torque), and a bone-putty mixture was used to simulate remodeling of the surrounding bone. CRR, TACT-R, and TACT-NR were tested by 6 radiologists using ROC-analysis. CRR and TACT-R were also tested for their quantitative ability. Results. Low Az-values were obtained for CRR (0.68; SD ⫽ .09), TACT-R (0.64; SD ⫽ .09), and TACT-NR (0.60; SD ⫽ .09). Differences between modalities were not statistically significant (ANOVA: P ⬎ .05). Lesion quantification was poor for both CRR (R2 ⫽ .03) and TACT-R (R2 ⫽ .13). Conclusions. Crown-root ratio and TACT are not valid for the detection and quantification of small oblique apical root resorption lesions. Imaging techniques with greater angular disparity between basis images reduce cross-talk effects and are likely to improve performance.
RADIOTHERAPY FOR TONGUE CARCINOMA IN A PATIENT WITH SYSTEMIC LUPUS ERYTHEMATOSUS Anitha Potluri, Robert J Dowset and Sanjay Mallya, University of Connecticut Health Center, Farmington, Conn
This study was sponsored in part by the Southern Association of Orthodontists.
Abstracts 265
Background. Systemic lupus erythematosus (SLE) is an autoimmune chronic inflammatory multisystem disease that is characterized by musculoskeletal, dermatologic, and immunological manifestations. There are several reports of serious acute and late skin and other tissue reactions to therapeutic radiation in SLE patients. A review of the literature reveals few case-control studies documenting the incidence of acute and late radiation therapy complications in patients with collagen vascular diseases. It was evident that patients with scleroderma and possibly rheumatoid arthritis suffer exaggerated sequelae from radiation therapy, but there was only a slight trend toward increased acute reactions in the patients with SLE. In previous studies patients with lupus showed only slight increase of acute reactions. The mechanism of interaction of radiation with skin and subcutaneous tissues in these patients is not clearly understood. Case Report. The present case report describes the sequelae of radiation therapy in a 41-year-old female with history of SLE and Sjo¨ gren’s syndrome. The patient was diagnosed with a stage II squamous cell carcinoma of the left lateral tongue and was treated surgically, with selective neck dissection of left neck at levels 1, 2, and 3. Four months later she developed recurrence of carcinoma in the left lateral tongue and a right neck mass at level 2. The neck mass was treated surgically with neck dissection. The patient was referred to combined chemo- and radiation therapy and made aware of the complications possible because of her existing condition of SLE. She received a total dose of 7400 cGy, with fractionated doses to include the oral cavity and neck, using opposed lateral technique and brachytherapy with interstitial Iridium-192 implants. The patient developed moderate to severe acute reactions— extensive mucositis, pancytopenia, radiation dermatitis, and thrush. Three months since her last radiation treatment, she still suffered from pain, xerostomia, fatigue, reduced mobility of the tongue, pharyngeal edema, and pain in the temporomandibular joint area with limited opening of the mouth. Discussion. The present case describes reactions to radiation therapy in a patient with SLE. The patient’s early reactions to radiation cannot be wholly attributed to her preexisting condition of SLE. They could be due to her combined modality treatment of chemo- and radiation therapy. As the patient is still in her early stages of recovery we do not know about the late effects. However, this case demonstrates that SLE is not an absolute contraindication for radiation treatment. Nevertheless, such patients should be advised of the possible increased risk of severe toxicity from radiation.
STORAGE PHOSPHOR PLATES: HOW DURABLE ARE THEY AS A DIGITAL DENTAL RADIOGRAPHIC SYSTEM? Aurelija Bedard, University of Missouri School of Dentistry, Kansas City, Mo Background. The exclusive use of digital radiography based on a storage phosphor system at the Univeristy of Missouri–Kansas City School of Dentistry raised some questions about the durability of the storage phosphor plates (SPPs). The digital images acquired from SPPs that have been repeatedly used seem to demonstrate a lower quality owing to the appearance of scratches. These scratches sometimes render the image completely undiagnostic and may lead to a “remake” of the radiograph. Our observations indicated that the durability of this imaging system may be limited, despite the manufacturer’s claim that the SPPs can be used indefinitely. Objective. The aim of this in vitro investigation was to evaluate the durability of storage phosphor plates (SPPs) as a digital dental imaging system and to detect the factors that may contribute to possible reduced durability. Methods and materials. One hundred forty new storage phosphor plates were divided in groups and exposed to the effects of the various handling steps during the image acquisition: Group 1 tested the effect of placement of the plates in protective barriers, group 2 the
266 Abstracts
effect of X-CP film holders on the plates, group 3 the effect of disposable film holders, and group 4 the effect of tje drum mounting process on the SPPs. An additional group of plates joined the existing plates used by the radiology clinic at the University of Missouri– Kansas City School of Dentistry and tested the additive effect of all these factors plus the effect of positioning the plates in patients’ mouths. The images resulting from the SPPs were regularly evaluated for the appearance of scratches as a sign of wear. They were rated by an oral radiologist using a 6-point scale (0 ⫽ no sign of wear, plate completely diagnostic; 5 ⫽ considerable wear, plate nondiagnostic). Results. Although the manufacturer claims that the storage phosphor plates can be used indefinitely, we found that 95% of our plates were rendered nondiagnostic after 50 uses. The effect of the mounting process of the SPPs for scanning seems to be considerable compared with the other factors. Inexperienced operators (mainly dental students), inexperienced staff, and the SPPs’ sensitivity to wear appear to be the factors that could account for our study’s results. Conclusions. This study indicated that the manufacturer’s claim for indefinite use of the storage phosphor plates as a digital imaging system seems to be questionable.
RADIOGRAPHIC PRESCRIPTIONS CLAIMED IN THE FLORIDA CHILD DENTAL MEDICAID PROGRAM 1998/ 9 –2002/3. D. K. Benn, University of Florida College of Dentistry, Gainesville, Fla Background. Frequency of radiographic examinations are often determined by surveys of dentists reporting their way of working rather than from claims for payment of procedures actually performed. Insurance claims data tends to lack detail, such as approximately 2 radiographic procedures per clinical examination for children aged 0-20 years.1 Objective. The objective was to determine the numbers of dental radiographic examinations claimed for patients aged 0- 20 years in a Florida Medicaid program over a 5-year period. Methods and materials. Spreadsheet data were supplied by the Florida Agency for Health Care Administration for (1) annual total claims for all dental providers who submitted a claim for patients aged 0- 20 years, (2) annual total claims for each procedure category, and (3) total number of providers. The numbers of annual claims for periodic and comprehensive oral examination were summed together as well as the numbers of 2BWs and 4BWs. The ratios for bitewing, selected periapical, full mouth series, intraoral occlusal, panoramic, and PA/lateral/Ceph skull radiographic procedures were compared to the annual total of exams. The ratios were also calculated for sealants and prophylaxes. Results. Over the 5-year period the number of annual clinical exams varied from 388,000 to 457,000. For every 100 exams claimed there were 45-48 bitewing exams, 1-2 full mouth series, 46-69 selected periapicals, 22-26 panoramics, 11-25 occlusals, 1 or fewer PA/lateral/Ceph skull views. There were 5 times as many 2BW claims as 4BW claims. Single BWs were rare. Sixty-one to 64 prophylaxes and 42-67 sealants were claimed per 100 exams. For single surface amalgams in primary/permanent teeth there were 14-22 claims and 9-12 2-surface amalgams. Conclusions. Approximately 50% of all examinations were associated with 2BWs, up to 69% with selected periapicals. Panoramic and occlusal views were associated with about 25% of exams. The frequency of prophylaxes and sealants are similar to selected periapical films and slightly more than bitewings. Occlusal views are similar to 1- or 2-surface amalgam restorations. In the absence of good epidemiological and diagnostic data it is impossible to assess if the claim rates are appropriate or not for this Medicaid population. It
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY February 2004 is difficult to understand the need for panoramic and occlusal radiographs at 25% of all examinations.
The author expresses gratitude to the Agency for Health Care Administration, Fla, and the Office of the Attorney General, Fla. REFERENCES 1. Leggott PJ, Robertson PB, del Aguila M, et al. Patterns of oral care in dental school and general dental practice. J Dent Educ 2002;66(4):541-7.
INCLUSION OF TOBACCO EXPOSURE AS A PREDICTIVE FACTOR FOR DECREASED BONE MINERAL CONTENT. Byron W. Benson and Jay D. Shulman, Baylor College of Dentistry and Texas A&M University Health Science Center, Dallas, Texas Background. Tobacco exposure has been implicated as a predictive risk index for decreased bone density that might result in osteoporosis.1 Other reported predictive indices include age, gender, race-ethnicity, menopausal status, activity level, body mass index, calcium intake, diabetic history, hormone replacement, steroid use, income ratio, education, and history of maternal osteoporosis.2 Cotinine, a metabolite of nicotine, is commonly used as a marker for tobacco exposure (active or passive). Serum cotinine is capable of detecting levels as low as 0.030 ng/ml, allowing quantitative measurement of exposure from environmental and active tobacco use.1 Objective. The study objective was to compare tobacco exposure to other predictive factors for low bone mineral content (BMC), as determined by dual-photon bone absorptiometry (DXA) in a national US sample. Methods and Materials. Publicly available survey and clinical examination data from the Third National Health and Nutrition Examination Survey 1988-1994 was used for this study. The survey included 33,994 subjects from 19,528 randomly selected representative US households. Of those surveyed, 30,818 were examined in a mobile center and 493 were examined at home. Clinical laboratory data included serum values for serum calcium and cotinine. BMC was assessed radiologically by DXA at 5 proximal femur sites. BMC values were adjusted for age, as well as height, weight, and bone area to correct for bone and body size.3 T-tests were used to compare continuous variables and chi-square tests to explore associations between categorical variables. Multivariate regression models were developed for each gender. Results. Intertrochanter BMC explained the most variation (highest R2) and was selected as the basis of the comparison. Serum cotinine had a significant inverse relationship to BMC in both males (P ⫽ .0069) and females (P ⫽ .0063). Racial-ethnic group and activity level were significant factors for both genders. Hormone replacement and steroid use was a significant factor in females. Milk intake and diabetic history were significant factors in males. Other factors included in this study did not have a significant association with BMC. Conclusions. Serum cotinine, as a marker for tobacco exposure, is a statistically significant risk factor for decreased BMC in both genders and should be included in multivariate regression models to predict low BMC.
REFERENCES 1. Gonzalez YM et al. Serum cotinine levels, smoking, and periodontal attachment loss. J Dent Res 1996;75:796-802. 2. Snelling AM, Crespo CJ, et al. Modifiable and nonmodifiable factors associated with osteoporosis in postmenopausal women. J Womens Health Gend Based Med 2001;10:57-65.
EARLY DETECTION AND QUANTITATIVE ASSESSMENT OF APICAL ROOT RESORPTION USING CROWNROOT RATIO AND TUNED-APERTURE COMPUTED TOMOGRAPHY (TACT). Andre´ Mol, Julie H. Mol, Onanong Chai-u-dom, and Donald A. Tyndall, University of North Carolina, Chapel Hill, NC, and Chulalongkorn University, Bangkok, Thailand Background. Apical root resorption (ARR) is a complication of orthodontic treatment without clear causative factors. The relationship between causative factors and ARR may be obscured by inaccuracies in current methods of detection and quantification. Twodimensional imaging, lack of image standardization, as well as orthodontic tooth movement and remodeling of the surrounding tissues all pose considerable challenges. Objective. The purpose of this study was to develop and test a tuned-aperture computed tomography (TACT) application and to assess the validity of the crown-root ratio (CRR) method for the detection and quantification of small oblique apical root resorption lesions. Methods and materials. A registered (R) and a nonregistered (NR) version of TACT were tested. In TACT-R, the detector moved with the tooth through mechanical standardization. TACT-NR allowed the tooth to move independently of the detector. Ten basis images with a maximum angular disparity of 20° were used. Oblique slicing of TACT-NR follow-up stacks was required for registration with baseline stacks. A slice shifting algorithm was applied to prevent drifting of cross-talk shadows. Twenty extracted maxillary incisors placed in a widened alveolus of a maxillary jaw segment served as test and control sites. Baseline images were acquired without lesions. Follow-up images were acquired with and without lesions. Lesions were created by cutting an oblique buccolingual segment of the root just below the apex. Teeth were moved between baseline and follow-up (rotation and torque), and a bone-putty mixture was used to simulate remodeling of the surrounding bone. CRR, TACT-R, and TACT-NR were tested by 6 radiologists using ROC-analysis. CRR and TACT-R were also tested for their quantitative ability. Results. Low Az-values were obtained for CRR (0.68; SD ⫽ .09), TACT-R (0.64; SD ⫽ .09), and TACT-NR (0.60; SD ⫽ .09). Differences between modalities were not statistically significant (ANOVA: P ⬎ .05). Lesion quantification was poor for both CRR (R2 ⫽ .03) and TACT-R (R2 ⫽ .13). Conclusions. Crown-root ratio and TACT are not valid for the detection and quantification of small oblique apical root resorption lesions. Imaging techniques with greater angular disparity between basis images reduce cross-talk effects and are likely to improve performance.
RADIOTHERAPY FOR TONGUE CARCINOMA IN A PATIENT WITH SYSTEMIC LUPUS ERYTHEMATOSUS Anitha Potluri, Robert J Dowset and Sanjay Mallya, University of Connecticut Health Center, Farmington, Conn
This study was sponsored in part by the Southern Association of Orthodontists.
Abstracts 265
Background. Systemic lupus erythematosus (SLE) is an autoimmune chronic inflammatory multisystem disease that is characterized by musculoskeletal, dermatologic, and immunological manifestations. There are several reports of serious acute and late skin and other tissue reactions to therapeutic radiation in SLE patients. A review of the literature reveals few case-control studies documenting the incidence of acute and late radiation therapy complications in patients with collagen vascular diseases. It was evident that patients with scleroderma and possibly rheumatoid arthritis suffer exaggerated sequelae from radiation therapy, but there was only a slight trend toward increased acute reactions in the patients with SLE. In previous studies patients with lupus showed only slight increase of acute reactions. The mechanism of interaction of radiation with skin and subcutaneous tissues in these patients is not clearly understood. Case Report. The present case report describes the sequelae of radiation therapy in a 41-year-old female with history of SLE and Sjo¨ gren’s syndrome. The patient was diagnosed with a stage II squamous cell carcinoma of the left lateral tongue and was treated surgically, with selective neck dissection of left neck at levels 1, 2, and 3. Four months later she developed recurrence of carcinoma in the left lateral tongue and a right neck mass at level 2. The neck mass was treated surgically with neck dissection. The patient was referred to combined chemo- and radiation therapy and made aware of the complications possible because of her existing condition of SLE. She received a total dose of 7400 cGy, with fractionated doses to include the oral cavity and neck, using opposed lateral technique and brachytherapy with interstitial Iridium-192 implants. The patient developed moderate to severe acute reactions— extensive mucositis, pancytopenia, radiation dermatitis, and thrush. Three months since her last radiation treatment, she still suffered from pain, xerostomia, fatigue, reduced mobility of the tongue, pharyngeal edema, and pain in the temporomandibular joint area with limited opening of the mouth. Discussion. The present case describes reactions to radiation therapy in a patient with SLE. The patient’s early reactions to radiation cannot be wholly attributed to her preexisting condition of SLE. They could be due to her combined modality treatment of chemo- and radiation therapy. As the patient is still in her early stages of recovery we do not know about the late effects. However, this case demonstrates that SLE is not an absolute contraindication for radiation treatment. Nevertheless, such patients should be advised of the possible increased risk of severe toxicity from radiation.
STORAGE PHOSPHOR PLATES: HOW DURABLE ARE THEY AS A DIGITAL DENTAL RADIOGRAPHIC SYSTEM? Aurelija Bedard, University of Missouri School of Dentistry, Kansas City, Mo Background. The exclusive use of digital radiography based on a storage phosphor system at the Univeristy of Missouri–Kansas City School of Dentistry raised some questions about the durability of the storage phosphor plates (SPPs). The digital images acquired from SPPs that have been repeatedly used seem to demonstrate a lower quality owing to the appearance of scratches. These scratches sometimes render the image completely undiagnostic and may lead to a “remake” of the radiograph. Our observations indicated that the durability of this imaging system may be limited, despite the manufacturer’s claim that the SPPs can be used indefinitely. Objective. The aim of this in vitro investigation was to evaluate the durability of storage phosphor plates (SPPs) as a digital dental imaging system and to detect the factors that may contribute to possible reduced durability. Methods and materials. One hundred forty new storage phosphor plates were divided in groups and exposed to the effects of the various handling steps during the image acquisition: Group 1 tested the effect of placement of the plates in protective barriers, group 2 the
266 Abstracts
effect of X-CP film holders on the plates, group 3 the effect of disposable film holders, and group 4 the effect of tje drum mounting process on the SPPs. An additional group of plates joined the existing plates used by the radiology clinic at the University of Missouri– Kansas City School of Dentistry and tested the additive effect of all these factors plus the effect of positioning the plates in patients’ mouths. The images resulting from the SPPs were regularly evaluated for the appearance of scratches as a sign of wear. They were rated by an oral radiologist using a 6-point scale (0 ⫽ no sign of wear, plate completely diagnostic; 5 ⫽ considerable wear, plate nondiagnostic). Results. Although the manufacturer claims that the storage phosphor plates can be used indefinitely, we found that 95% of our plates were rendered nondiagnostic after 50 uses. The effect of the mounting process of the SPPs for scanning seems to be considerable compared with the other factors. Inexperienced operators (mainly dental students), inexperienced staff, and the SPPs’ sensitivity to wear appear to be the factors that could account for our study’s results. Conclusions. This study indicated that the manufacturer’s claim for indefinite use of the storage phosphor plates as a digital imaging system seems to be questionable.
RADIOGRAPHIC PRESCRIPTIONS CLAIMED IN THE FLORIDA CHILD DENTAL MEDICAID PROGRAM 1998/ 9 –2002/3. D. K. Benn, University of Florida College of Dentistry, Gainesville, Fla Background. Frequency of radiographic examinations are often determined by surveys of dentists reporting their way of working rather than from claims for payment of procedures actually performed. Insurance claims data tends to lack detail, such as approximately 2 radiographic procedures per clinical examination for children aged 0-20 years.1 Objective. The objective was to determine the numbers of dental radiographic examinations claimed for patients aged 0- 20 years in a Florida Medicaid program over a 5-year period. Methods and materials. Spreadsheet data were supplied by the Florida Agency for Health Care Administration for (1) annual total claims for all dental providers who submitted a claim for patients aged 0- 20 years, (2) annual total claims for each procedure category, and (3) total number of providers. The numbers of annual claims for periodic and comprehensive oral examination were summed together as well as the numbers of 2BWs and 4BWs. The ratios for bitewing, selected periapical, full mouth series, intraoral occlusal, panoramic, and PA/lateral/Ceph skull radiographic procedures were compared to the annual total of exams. The ratios were also calculated for sealants and prophylaxes. Results. Over the 5-year period the number of annual clinical exams varied from 388,000 to 457,000. For every 100 exams claimed there were 45-48 bitewing exams, 1-2 full mouth series, 46-69 selected periapicals, 22-26 panoramics, 11-25 occlusals, 1 or fewer PA/lateral/Ceph skull views. There were 5 times as many 2BW claims as 4BW claims. Single BWs were rare. Sixty-one to 64 prophylaxes and 42-67 sealants were claimed per 100 exams. For single surface amalgams in primary/permanent teeth there were 14-22 claims and 9-12 2-surface amalgams. Conclusions. Approximately 50% of all examinations were associated with 2BWs, up to 69% with selected periapicals. Panoramic and occlusal views were associated with about 25% of exams. The frequency of prophylaxes and sealants are similar to selected periapical films and slightly more than bitewings. Occlusal views are similar to 1- or 2-surface amalgam restorations. In the absence of good epidemiological and diagnostic data it is impossible to assess if the claim rates are appropriate or not for this Medicaid population. It
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY February 2004 is difficult to understand the need for panoramic and occlusal radiographs at 25% of all examinations.
The author expresses gratitude to the Agency for Health Care Administration, Fla, and the Office of the Attorney General, Fla. REFERENCES 1. Leggott PJ, Robertson PB, del Aguila M, et al. Patterns of oral care in dental school and general dental practice. J Dent Educ 2002;66(4):541-7.
INCLUSION OF TOBACCO EXPOSURE AS A PREDICTIVE FACTOR FOR DECREASED BONE MINERAL CONTENT. Byron W. Benson and Jay D. Shulman, Baylor College of Dentistry and Texas A&M University Health Science Center, Dallas, Texas Background. Tobacco exposure has been implicated as a predictive risk index for decreased bone density that might result in osteoporosis.1 Other reported predictive indices include age, gender, race-ethnicity, menopausal status, activity level, body mass index, calcium intake, diabetic history, hormone replacement, steroid use, income ratio, education, and history of maternal osteoporosis.2 Cotinine, a metabolite of nicotine, is commonly used as a marker for tobacco exposure (active or passive). Serum cotinine is capable of detecting levels as low as 0.030 ng/ml, allowing quantitative measurement of exposure from environmental and active tobacco use.1 Objective. The study objective was to compare tobacco exposure to other predictive factors for low bone mineral content (BMC), as determined by dual-photon bone absorptiometry (DXA) in a national US sample. Methods and Materials. Publicly available survey and clinical examination data from the Third National Health and Nutrition Examination Survey 1988-1994 was used for this study. The survey included 33,994 subjects from 19,528 randomly selected representative US households. Of those surveyed, 30,818 were examined in a mobile center and 493 were examined at home. Clinical laboratory data included serum values for serum calcium and cotinine. BMC was assessed radiologically by DXA at 5 proximal femur sites. BMC values were adjusted for age, as well as height, weight, and bone area to correct for bone and body size.3 T-tests were used to compare continuous variables and chi-square tests to explore associations between categorical variables. Multivariate regression models were developed for each gender. Results. Intertrochanter BMC explained the most variation (highest R2) and was selected as the basis of the comparison. Serum cotinine had a significant inverse relationship to BMC in both males (P ⫽ .0069) and females (P ⫽ .0063). Racial-ethnic group and activity level were significant factors for both genders. Hormone replacement and steroid use was a significant factor in females. Milk intake and diabetic history were significant factors in males. Other factors included in this study did not have a significant association with BMC. Conclusions. Serum cotinine, as a marker for tobacco exposure, is a statistically significant risk factor for decreased BMC in both genders and should be included in multivariate regression models to predict low BMC.
REFERENCES 1. Gonzalez YM et al. Serum cotinine levels, smoking, and periodontal attachment loss. J Dent Res 1996;75:796-802. 2. Snelling AM, Crespo CJ, et al. Modifiable and nonmodifiable factors associated with osteoporosis in postmenopausal women. J Womens Health Gend Based Med 2001;10:57-65.