Diagnostic performance of general dental practitioners after lecture in identifying post-menopausal women with low bone mineral density by panoramic radiographs

OBJECTIVES: Mandibular cortical erosion detected on panoramic radiographs may be useful for identifying post-menopausal women with low skeletal bone mineral density (BMD). The purposes of this study were to calculate the diagnostic performance of general dental practitioners (GDPs) who attended a lecture on identifying post-menopausal women with low BMD from findings on panoramic radiographs and to evaluate the influence of GDPs' age on diagnostic performance. METHODS: After a 1 h lecture, 111 GDPs were asked to classify the mandibular cortex (normal or eroded) on panoramic radiographs obtained from 100 post-menopausal women who have had skeletal BMD assessment. Low BMD was defined as a BMD T score of -1.0 or less. Diagnostic performance was analysed by comparing two groups classified by mandibular cortex (women with normal cortex and women with any eroded cortex) with those classified by BMD (women with normal BMD and women with low BMD). RESULTS: The mean sensitivity, specificity, positive predictive value, negative predictive value, accuracy and likelihood ratio for a positive risk result were 73.0% (95% confidence interval [CI]; 71.3 to 74.7%), 49.0% (95% CI; 46.4 to 51.5%), 66.9% (95% CI; 66.0 to 67.8%), 57.0% (95% CI; 55.8 to 58.2%), 62.9% (95% CI; 62.1 to 63.7%) and 1.51 (95% CI; 1.44 to 1.58), respectively. GDPs' age did not influence diagnostic performance. CONCLUSIONS: Our results suggest that 73.0% of women who had low skeletal BMD can be identified by GDPs after a lecture on the use of panoramic radiographs as an aid in diagnosing low BMD; however, the diagnostic performance may not be influenced by GDPs' age.     

Diagnostic efficacy of alveolar bone loss of the mandible for identifying postmenopausal women with femoral osteoporosis

OBJECTIVES: Mandibular cortical width (MCW) detected on panoramic radiographs may be useful for identifying postmenopausal women with osteoporosis. There is little known regarding whether alveolar bone loss (ABL) of the mandible detected on panoramic radiographs is a potentially accurate screening tool for osteoporosis in comparison with MCW. The purpose of this study was to evaluate whether ABL of the mandible on panoramic radiographs is useful for identifying femoral osteoporosis in postmenopausal women in comparison with MCW. METHODS: Three hundred and fifty-four Japanese postmenopausal women (mean age+/-SD, 56.8+/-7.7 years) were recruited for this study. Femoral BMD was measured by dual energy X-ray absorptiometry. Panoramic radiographs were obtained to estimate ABL of the mandible and MCW. RESULTS: A multiple regression analysis revealed that femoral BMD was significantly associated with MCW (P<0.001), weight (P<0.001), age (P<0.001) and ABL of the mandible (P=0.029; adjusted r(2)=0.380). The area under the ROC curve (AUC) for identifying femoral osteoporosis was 0.609 [95% confidence interval (CI), 0.523-0.696] for ABL of the mandible and 0.779 (95% CI, 0.713-0.844) for MCW, respectively. AUC for ABL of the mandible indicated less accuracy. CONCLUSIONS: Our results suggest that ABL of the mandible on panoramic radiographs may not be useful for identifying postmenopausal women with femoral osteoporosis in comparison with MCW.     

Risk of vertebral osteoporosis in post-menopausal women with alterations of the mandible

BACKGROUND: Previous studies have suggested that a thin or eroded cortex of the mandible detected on dental panoramic radiographs is associated with low vertebral bone mineral density (BMD) or osteoporosis. However, those studies did not estimate the multivariate-adjusted risk for low vertebral BMD or osteoporosis associated with alterations of the mandible. METHODS: BMD of the lumbar vertebrae (L2-L4) was compared among quartiles of cortical width and among three cortical shape categories in 450 post-menopausal women (mean age, 57.2 years), adjusted for potential confounders. The odds ratios for low BMD or osteoporosis according to cortical width and shape were also calculated. RESULTS: Significant associations were found between cortical width and shape, and vertebral BMD. The odds ratios for low vertebral BMD associated with the second, third and lowermost quartiles of cortical width were 1.71 (95% confidence interval (CI), 0.96-3.05), 2.30 (95% CI, 1.29-4.11) and 5.43 (95% CI, 2.16-10.71), respectively, compared with the uppermost quartile. The odds ratios for osteoporosis according to cortical width category were similar to those for low BMD. The odds ratios for low BMD associated with mildly to moderately and severely eroded cortices were 3.85 (95% CI, 2.37-6.25) and 7.84 (95% CI, 2.57-23.90), respectively, compared with normal cortex. The odds ratios for osteoporosis associated with mildly to moderately and severely eroded cortices were 4.73 (95% CI, 2.54-8.80) and 14.73 (95% CI, 6.14-35.47), respectively. CONCLUSIONS: Post-menopausal women with alterations of the mandible may have an increased risk for low vertebral BMD or osteoporosis.     

Detecting young Japanese adults with undetected low skeletal bone density using panoramic radiographs

Objective

The cortical width below the mental foramen of the mandible determined from panoramic radiographs is a useful screening tool for identifying elderly individuals with a low skeletal bone mineral density (BMD). However, whether the mandible cortical width (MCW) is useful for identifying a low skeletal BMD in men and women of 40 years or younger is not known.

Methods

The BMD of the calcaneus was measured by ultrasonography bone densitometry in 158 men and 76 women aged 18–36 years. A logistic regression analysis adjusted for age was used to calculate the odds ratios and 95% confidence interval (CI) of having a low calcaneal BMD, according to the quartiles of the MCW. The areas under the receiver operator characteristic curve (AUC) for identifying participants with a low calcaneal BMD using the MCW were assessed to evaluate the diagnostic efficacy of the MCW.

Results

In men, the adjusted odds ratios of a low calcaneal BMD associated with the second, third and lowest quartiles of MCW were 5.66 (95% CI, 0.61–52.23), 5.43 (95% CI, 0.59–50.18) and 33.22 (95% CI, 3.97–276.94), respectively, compared with the highest quartile, while no significant trend in the adjusted odds ratios was observed in women. The AUC for identifying participants with a low calcaneal BMD based on the MCW was 0.796 (95% CI, 0.702–0.890) in men and 0.593 (95% CI, 0.398–0.788) in women.

Conclusion

MCW determined from panoramic radiographs can be used to identify undetected low calcaneus BMD in young adult men, but not in young adult women.     

Validation of dental panoramic radiography measures for identifying postmenopausal women with spinal osteoporosis

OBJECTIVE: Measurements of mandibular inferior cortical shape and width detected on dental panoramic radiographs may be a useful screening tool for spinal osteoporosis in postmenopausal women. The purposes of this study were to clarify whether these measures are validated compared with simple screening tools based on questionnaires, such as the osteoporosis self-assessment tool (OST) and whether these measures can be used in postmenopausal women with histories of hysterectomy, oophorectomy, or estrogen use. SUBJECTS AND METHODS: We calculated the diagnostic performances of panoramic measurements and the OST for identifying women with spinal osteoporosis in both 159 healthy postmenopausal and 157 postmenopausal women with histories of hysterectomy, oophorectomy, or estrogen use. Spinal osteoporosis was defined as a bone mineral density T score of -2.5 or less at the lumbar spine. Cortical shape and width were evaluated on dental panoramic radiographs. Receiver operating characteristic curve analyses were used to determine the optimal cutoff thresholds for cortical width and the OST in healthy postmenopausal women. RESULTS: The sensitivity and specificity, respectively, for identifying women with spinal osteoporosis were 89.5% and 33.9% for cortical width, 86.8% and 57.8% for the OST, and 86.8% and 63.6% for cortical shape in healthy postmenopausal women. Sensitivity and specificity, respectively, were 92.5% and 35.0% for cortical width, 72.5% and 58.1% for the OST, and 80.0% and 64.1% for cortical shape in postmenopausal women with histories of hysterectomy, oophorectomy, or estrogen use. CONCLUSION: Dentists may be able to refer postmenopausal women with suspected spinal osteoporosis for bone densitometry on the basis of dental panoramic radiographs with diagnostic performance similar to that of osteoporosis screening tools based on questionnaires.     

The relation between bone mineral density in the heel and pixel intensity in the mandibular jaw bone among elderly women

Objectives

The purpose of this study was to investigate the correlation between pixel intensity (PI) in digital radiographs of the lower jaw and bone mineral density (BMD) in the heels of post-menopausal women (as measured with DXL, a combination of dual energy X-ray absorptiometry and lasers).

Methods

Two intraoral periapical digital radiographs were taken in the right and left mandible premolar region, and the digital images were analysed by a computer program (Dimaxis) regarding PI. As the radiographs were taken, the BMD of the patient''s left heel was measured via a portable Calscan device. The patient answered a questionnaire concerning risk factors. The correlation between variables was analysed using statistical tests.

Results

A significant correlation was found between the PI in the left (P = 0.001) and right (P = 0.004) mandible and the BMD of the left heel for the whole group. A pronounced correlation was found to exist for women > 70 years old. Based on a cut-off value of the PI, to differentiate between healthy individuals and those who required further analysis for osteoporosis, the following values were obtained: sensitivity 0.74, specificity 0.50, positive predictive value 0.77 and negative predictive value 0.46.

Conclusion

A positive correlation was found between PI in digital radiographs of the mandible and the BMD of the heel. The low predictive value does not allow any definite conclusions to be drawn from the present study. A reasonable recommendation could be for future studies to employ a larger study population to explore the effect on this value.     

The effect of region of interest selection on dual energy X-ray absorptiometry measurements of the calcaneus in 55 post-menopausal women

Bone mineral density (BMD) of the calcaneus was assessed by dual energy X-ray absorptiometry (DXA) in four different regions of the calcaneus in 20 pre-menopausal and 55 post-menopausal women, none of whom were on treatment or suffering from conditions affecting bone. The total body option in the small animal software package of a Lunar DPX-L bone densitometer was used. The precision of the technique (%CV) varied from 0.7 to 2.2% depending on the region scanned. For post-menopausal women, BMD results in the mid and posterior parts of the calcaneus varied by < 7% while BMD in the anterior region was about 20% lower. DXA of the calcaneus was compared with measurements at the spine (L2-L4) and hip (femoral neck) and changes with age were estimated from cross-sectional data. BMD of the calcaneus was significantly reduced in 28 post-menopausal women with low lumbar spine BMD (-2SD) compared with women with normal spine BMD. Calcaneal BMD was significantly correlated to axial BMD (r = 0.45-0.77) and to age (r = 0.45 to -0.63). For a subgroup of 33 post-menopausal women measured twice after approximately 1 year, calcaneus BMD decreased by between 1.2% and 2.5% while axial BMD showed no significant change. Unlike spine or femoral neck BMD, the decrease in calcaneus BMD was significantly greater in women with low spine BMD than in normal women, possibly indicating improved detection of skeletal changes. The optimum measurement sites for BMD in the calcaneus were within the mid or posterior part of the calcaneus or enclosing the whole posterior calcaneus. The calcaneus was shown to be a precise, sensitive and simple measurement site suitable for the assessment of osteoporosis, especially in the elderly where degenerative changes in the spine and hip can complicate BMD assessment.     

Individualized periapical radiography determined by clinical and panoramic examination.

The efficiency of panoramic radiography compared with full-mouth periapical examination is an unresolved problem. The diagnostic yield of periapical lesions when the clinical signs and symptoms and the findings from a panoramic radiograph served as the basis for an individualized periapical radiographic examination was studied. Two hundred patients were examined clinically and radiographically. The periapical status was assessed step by step with access to increasing numbers of radiographs. For the clinical examination, the sensitivity was 0.24, the positive predictive value 0.62, the specificity 0.98, the negative predictive value 0.90 and the likelihood ratio for the positive test result 12. For radiographs indicated by the clinical examination plus the panoramic radiograph and selected periapical radiographs, both the sensitivity and the positive predictive value were 0.91, the specificity and the negative predictive value 0.99 each and the likelihood ratio was 91. False findings were twice as frequent in the upper as in the lower arch and particularly found in the incisor and premolar regions. In 30% of the patients no periapical radiograph was needed to supplement the panoramic radiograph. In the other patients, two supplementary periapical radiographs were needed on average. We conclude that the information obtained from the clinical and panoramic examinations supplemented with no more than two periapical radiographs will result in a high diagnostic yield on the periapical status.     

Osteoporosis research: A dental perspective

Purpose: There have been many articles reviewing current research into the diagnosis and treatment of osteoporosis. Few are aware, however, of the large amount of research within the dental field concerning the relationship between mandibular bone mineral density and systemic osteoporosis. It has been suggested that, in the absence of a national screening programme for osteoporosis, dental practitioners may be in a position to identify those patients who appear to be at risk by evaluation of dental radiographs. In order to do this, however, radiographic indicators of osteoporosis in the mandible must be identified and the relationship between mandibular bone mineral density (BMD) and that of other skeletal areas established. The purpose of this article was to provide a review of the literature in this area.Methods: The findings of a number of the most prominent studies, using a range of methods including histomorphometric analyses, radiographic densitometry and the more sophisticated computerized absorptiometry and densitometry techniques, are described and their findings compared.Results: The results of these studies suggest that there is a moderate correlation between mandibular BMD and that of other skeletal regions. Opinion concerning the use of plain films in the identification of osteoporotic patients, however, is mixed.Conclusions: Whilst there is a relationship between mandibular and regional bone density, further, well controlled research is required in order to answer certain pragmatic questions regarding the diagnostic validity of dental radiographs in the identification of patients who would most benefit from bone densitometry assessment.     

The differences in panoramic mandibular indices and fractal dimension between patients with and without spinal osteoporosis

OBJECTIVES: The aims of this study were to evaluate the relationship between osteoporosis, oral signs, body mass index and age; and to assess the possibility of using these parameters as an indicator of post-menopausal osteoporosis. The oral signs were panoramic-based mandibular indices, such as cortical width, cortical index, panoramic mandibular index and mandibular crest resorption degree; the number of teeth and fractal dimension analysis. METHODS: Forty-eight post-menopausal women between the ages of 40 years and 64 years were evaluated. Mandibular indices and the number of mandibular teeth were measured and evaluated from panoramic radiographs and fractal dimension was calculated from the direct digital periapical radiographs of the mandibular premolar-molar region in box-counting method. Weight, height, menopausal status and age of the patients were recorded by questionnaire. Bone mineral densities of the patients were measured with dual energy X-ray absorptiometry. RESULTS: In this study there were no statistically significant differences between the osteoporotic and non-osteoporotic patients for cortical width, panoramic mandibular index, alveolar crest resorption degree, fractal dimension and the number of mandibular teeth, but there was a difference for cortical index. Binary logistic regression analyses demonstrated that age (P = 0.015) was an important risk factor for osteoporosis. CONCLUSION: The results of this study demonstrated that osteoporotic patients were more likely to have altered inferior cortex morphology than non-osteoporotic patients and age is an important risk factor for osteoporosis.     

Cleidocranial dysplasia: radiological appearances on dental panoramic radiography.

OBJECTIVE: To report the effectiveness of dental panoramic radiography in identifying features pathognomonic for cleidocranial dysplasia. METHODS: Panoramic radiographs of nine male Caucasian patients with cleidocranial dysplasia are analysed. RESULTS: In addition to the established dental complications of failure of eruption of the permanent dentition and multiple supernumerary teeth, morphological abnormalities of the maxilla and mandible, particularly in the ascending ramus and coronoid process were present. CONCLUSION: Dental panoramic radiography is a valuable adjunct in confirming the diagnosis of cleidocranial dysplasia.     

Digital orthopantomograms in osteoporosis detection: mandibular density and mandibular radiographic indices as skeletal BMD predictors

Objectives:

To determine the correlation of skeletal bone mineral density (BMD) with mandibular density and mandibular radiographic indices estimated on digital panoramic radiographs.

Methods:

Study comprised 112 female subjects older than 45 years. Digital panoramic radiographs were taken, and patients were referred to densitometric measuring (dual energy X-ray absorptiometry) of BMD in the hip bones and lumbar spine regions (L1–L4). On the radiographs, mandibular bone density was estimated and the following indices were measured by the DIGORA^® software (Soredex, Tuusula, Finland): mental index (MI), gonial index (GI), antegonial index (AI), panoramic mandibular index (PMI) and alveolar crest resorption degree (M/M). Mandibular cortical index (MCI) was visually estimated.

Results:

Mandibular density and visual index MCI are significant predictors of hip and spine BMD. Mandibular density was marked by a significant square trend: it decreased until the age of 54 years and remained constant until the age of 64 years when it started to increase. Significant correlations were found between MI, AI and PMI values and BMD in the hip but not in the lumbar spine region. The GI and M/M values did not show statistically significant correlations with BMD of either region.

Conclusions:

Mandibular bone density and mandibular radiographic indices are useful in detecting patients with decreased BMD. The applicability of orthopantomograms in diagnosing osteoporosis/osteopenia should be recognized as the potential greatest benefit of this everyday diagnostic method in dental practice.     

Diagnostic accuracy of panoramic radiography in the detection of calcified carotid artery

OBJECTIVES: The purpose of this study was to assess the diagnostic accuracy of the panoramic radiograph in the detection of carotid artery calcification using CT as the gold standard. METHODS: 110 dental patients (average age 65.2 years, range 50-82 years) with both panoramic radiographs and CT scans available were selected for the evaluation of carotid artery calcification. Two oral and maxillofacial radiologists interpreted the panoramic radiographs for the presence of carotid artery calcification. CT scans were independently interpreted by a neuroradiologist. RESULTS: The accuracy of panoramic radiographs in the detection of carotid artery calcification was 62.3%. The sensitivity and the specificity were 22.2% and 90.0%, respectively. CONCLUSIONS: Panoramic radiography has a moderate diagnostic accuracy in the detection of carotid artery calcification, but the sensitivity is low.     

Longitudinal changes in mandibular bone mineral density compared with hip bone mineral density and quantitative ultrasound at calcaneus and hand phalanges

The aim of this prospective study was to evaluate changes in bone mineral density (BMD) of the mandible (m-BMD) compared with hip BMD and ultrasound parameters of the calcaneus and hand phalanges over 28 months. The study group consisted of 18 post-menopausal edentulous women with no reasons known to affect bone metabolism, such as disease or medication. Each woman had undergone natural menopause. No previous fractures were noted. Measurements were performed at baseline and repeated after 28 months. Bone status was assessed by measuring BMD using dual energy X-ray absorptiometry (DXA) at the mandible and hip and by measuring speed of sound (SOS), broadband ultrasound attenuation (BUA), stiffness index (SI) and amplitude-dependent SOS (Ad-SOS) using quantitative ultrasound at the calcaneus and phalanges of the hand. The coefficient of variation for mandibular measurements was 2.06%. BMD of the mandible, femoral neck and Ward's triangle decreased significantly (-7.54%, -1.2%, -1.97% per year, respectively, p<0.05), whilst BUA, SI and Ad-SOS decreased, but not significantly (-1.1%, -0.47%, -0.08% per year, respectively). Both SOS and BMD of the trochanter had almost the same value without significant differences. The least significant change (LSC), denoting the minimum difference between two successive results in an individual that can be considered to reflect a real change, was calculated. With the exception of changes in m-BMD, no significant changes were observed at any of the sites for the majority of the women (39-89%). 67% of women had a decrease in m-BMD greater than the LSC and 22% had an increase in m-BMD greater than the LSC. Apart from the mandible, other sites showing a large percentage of women with a decrease in BMD greater than the LSC were the Ward's triangle (39%) and the femoral neck (28%). In conclusion, a 28-month longitudinal study of post-menopausal women revealed mandibular bone loss assessed by DXA to be much higher than in other skeletal sites.     

Digital X-ray radiogrammetry better identifies osteoarthritis patients with a low bone mineral density than quantitative ultrasound

This study assessed the ability of quantitative ultrasound (QUS) and digital X-ray radiogrammetry (DXR) to identify osteopenia and osteoporosis in patients with knee osteoarthritis (OA). One hundred and sixty-one patients with painful knee OA (81 men, 80 women; age 62.6±9.2 years, range 40–82 years) were included in this cross-sectional study and underwent dual-energy X-ray absorptiometry (DXA) of both hips and the lumbar spine, QUS of the phalanges and calcanei of both hands and heels, and DXR using radiographs of both hands. Unpaired t-test, Mann-Whitney U test, ROC analysis and Spearman’s rank correlation were used for comparisons and correlation of methods. Using DXA as the reference standard, we defined a low bone mineral density (BMD) as a T-score ≤−1.0 at the lumbar spine or proximal femur. In contrast to phalangeal or calcaneal QUS, DXR was able to discriminate patients with a low BMD at the lumbar spine (p<0.0001) or hips (p<0.0001). ROC analysis showed that DXR had an acceptable predictive power in identifying OA patients a low hip BMD (sensitivity 70%, specificity 71%). Therefore, DXR used as a screening tool could help in identifying patients with knee OA for DXA.     

A false presence of bifid mandibular canals in panoramic radiographs

Objectives

This study was performed in order to verify bifid mandibular canals revealed from panoramic radiographic results.

Methods

1000 panoramic radiographs from dental patients and the panorama, cone beam CT (CBCT) and micro-CT from 40 dry mandibles were examined for bifid mandibular canals. The results were confirmed by a stereoscopic and histological examination of the cross-sectioned mandibles.

Results

The prevalence of bifid canals detected from the panoramic radiographs was 0.038. The panoramic radiographs from one dry mandible showed two separate radiolucent mandibular canal-like structures delineated by radio-opaque lines. However, a stereoscopic and histological examination of a cross-section of the mandible showed that only one canal was a true canal containing neurovascular bundles: the other was false, reflecting merely a bony trabecular pattern.

Conclusions

The presence of bifid mandibular canals determined by panoramic radiography should be judged with great caution in relation to dental surgery.     

Magnification rate of digital panoramic radiographs and its effectiveness for pre-operative assessment of dental implants

Objectives

The purpose of this study was to determine the accuracy and effectiveness of digital panoramic radiographs for pre-operative assessment of dental implants.

Methods

We selected 86 patients (221 implants) and calculated the length of the planned implant based on the distance between a selection of critical anatomical structures and the alveolar crest using the scaling tools provided in the digital panoramic system. We analysed the magnification rate and the difference between the actual inserted implant length and planned implant length according to the location of the implant placement and the clarity of anatomical structures seen in the panoramic radiographs.

Results

There was no significant difference between the planned implant length and actual inserted implant length (P > 0.05). The magnification rate of the width and length of the inserted implants, seen in the digital panoramic radiographs, was 127.28 ± 13.47% and 128.22 ± 4.17%, respectively. The magnification rate of the implant width was largest in the mandibular anterior part and there was a significant difference in the magnification rate of the length of implants between the maxilla and the mandible (P < 0.05). When the clarity of anatomical structures seen in the panoramic radiographs is low, the magnification rate of the width of the inserted implants is significantly higher (P < 0.05), but there is no significant difference between the planned implant length and actual inserted implant length according to the clarity of anatomical structures (P < 0.05).

Conclusions

Digital panoramic radiography can be considered a simple, readily available and considerably accurate pre-operative assessment tool in the vertical dimension for dental implant therapy.     

Accuracy of digital and film panoramic radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies

OBJECTIVES: To compare the accuracy of digital and film panoramic radiographs for determining (1) the position and morphology of mandibular third molars before surgical removal and (2) the prevalence of dental anomalies and pathologies. METHODS: Three hundred and eighty-eight third mandibular molars were available for examination. Position and morphology of third molars observed on film radiographs and on digital panoramic images from five systems (DenOptix, DigiDent, Digora, Dimax2 and Orthophos Plus) were recorded by two observers and were compared with surgeons' findings at the time of the operation (gold standard). One observer further recorded the prevalence of dental anomalies and pathologies on both imaging modalities. RESULTS: Few differences were found between the digital and film-based panoramic systems in the assessment of accuracy of position and morphology of mandibular third molars. The prevalence of dental anomalies and pathologies determined with the two modalities was roughly similar. CONCLUSION: The five digital panoramic systems evaluated in this study were equally as useful for third molar treatment planning and diagnosis of dental anomalies and pathologies as conventional film-based panoramic radiographs.     

Fractal dimension on dental radiographs

OBJECTIVES: (1) To compare fractal dimension (FD) from periapical radiographs with FD from panoramic radiographs; (2) to correlate FD with cortical thickness and morphology; and (3) to correlate FD with a reported history of osteoporotic fractures. METHODS: Information on fracture and smoking history was obtained by a telephone interview with 281 elderly (>60 years of age) patients who had periapical and panoramic radiographs exposed on the same date. FD was measured in several locations on both types of radiograph. Mandibular cortical thickness and morphology were obtained from the panoramic radiograph. RESULTS: FD measured in the mandible was lower than FD in the maxilla. Same-jaw measurements had a higher correlation than same-side measurements. FD measured on panoramic radiographs was lower than FD from periapical radiographs. There was a negative correlation between cortical thickness and FD. FD was higher in subjects with more mandibular cortical porosities and resorption. The mean panoramic FD from subjects with a history of osteoporotic fractures was significantly higher, after adjusting for smoking, gender, age, height and weight. CONCLUSIONS: FD measured on panoramic radiographs is lower than FD measured on periapical radiographs. FD is higher in both types of radiograph in subjects with a thinner, severely eroded mandibular cortex and a history of osteoporotic fractures. This study confirms other reports that FD increases when bone mass decreases. In addition, it suggests that panoramic radiographs can be used as a possible alternative for the measurement of FD to periapical radiographs.