|Year : 2015 | Volume
| Issue : 2 | Page : 183-188
Mandibulo-osseous predictors of osteoporosis: A double-blind study on the correlation and comparison of mental index with bone mineral density in post-menopausal women
Shefali Waghray1, Nagalaxmi Velpula2, Balaji Gandhi Babu Dara1, Mahesh Kumar Duddu3, Vaishali Narayen4, Neeharika Satya Jyothi Allam1
1 Department of Oral Medicine and Radiology, Panineeya Mahavidhyalaya Institute of Dental Sciences and Research Centre, Hyderabad, Telangana, India
2 Department of Oral Medicine and Radiology, Sri Sai College of Dental Surgery, Vikarabad, Telangana, India
3 Department of Pediatric and Preventive Dentistry, G Pulla Reddy Dental College and Hospital, Kurnool, Andhra Pradesh, India
4 Department of Oral and Maxillofacial Pathology, Government Dental College and Hospital, Hyderabad, India
|Date of Submission||25-Oct-2014|
|Date of Acceptance||17-Oct-2015|
|Date of Web Publication||21-Nov-2015|
86, Gruhalaxmi Colony, Vikrampuri, Secunderabad - 500 015, Telangana
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Osteoporosis is a metabolic bone disease characterized by microarchitectural deterioration in bone tissue leading to fractures, and is essentially a preventable disease when detected in the early stages. Novel methods for early identification of osteoporosis can have a great impact in combating this otherwise progressive disease. Aims: The present study was conducted with the objectives of evaluating the precision of a radiomorphometric index [mental index (MI)] measured on a panoramic radiograph in early diagnosis of osteoporosis and finding its correlation with bone mineral density (BMD) measured by digital X-ray radiogrammetry method. Materials and Methods: The study consisted of 71 women who were in natural menopause. The MI was calculated by two investigators, with each investigator recording two sets of measurements. The BMD was assessed and the T-score was obtained by digital X-ray radiogrammetry method. Based on the T-score obtained, the patients were divided into three study groups of normal (n = 24), osteopenic (n = 30), and osteoporotic (n = 17). The values obtained were tabulated for statistical analysis. Results: In the present study, it was found that there was a statistically significant difference in the mean scores of MI among normal, osteopenic, and osteoporotic subjects. Normal subjects had significantly higher MI (P < 0.001) than the osteopenic subjects and, similarly, the osteopenic subjects had significantly higher MI (P < 0.001) than the osteoporotic subjects. The inter- and intra-investigator variability was found to be low. Conclusion: Based on the results of the present study, it was concluded that a simple radiomorphometric index (MI) which is relatively easier to measure on a panoramic radiograph can be an indicator of osteoporosis and may aid in early detection and treatment planning of one of the most prevalent metabolic bone diseases.
Keywords: Digital radiogrammetry, mental index, osteoporosis, panoramic radiograph
|How to cite this article:|
Waghray S, Velpula N, Dara BG, Duddu MK, Narayen V, Allam NS. Mandibulo-osseous predictors of osteoporosis: A double-blind study on the correlation and comparison of mental index with bone mineral density in post-menopausal women. J Indian Acad Oral Med Radiol 2015;27:183-8
|How to cite this URL:|
Waghray S, Velpula N, Dara BG, Duddu MK, Narayen V, Allam NS. Mandibulo-osseous predictors of osteoporosis: A double-blind study on the correlation and comparison of mental index with bone mineral density in post-menopausal women. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2021 Jul 29];27:183-8. Available from: https://www.jiaomr.in/text.asp?2015/27/2/183/170134
| Introduction|| |
Osteoporosis is defined as a skeletal disorder characterized by low bone mass leading to enhanced bone fragility and consequent increase in fracture risk.  Human skeleton undergoes a continuous physiologic decrease in bone mass with advancing age. Women lose more mineralized bone than men, especially after menopause. With advancing disease, bone loss and fractures may ensue. Since the disease is preventable, diagnostic techniques which can identify osteoporosis are of major importance. Groen et al. were the first to suggest an association between osteoporosis and oral bone loss in the year 1960.  A number of investigators have stated the importance of a panoramic radiograph in the detection of progressive loss of alveolar bone as a manifestation of osteoporosis. ,, In the last four decades, various researchers have reported osteoporosis to be diagnosable through oral radiographs. In previous studies, it was reported that the radiographic trabecular pattern shows correlation with bone mineral density (BMD). , But measurement of such a pattern on a radiograph is time consuming and difficult in a normal dental setup. Reproducibility of the radiomorphometric indices is of major importance in using them as screening tools for osteoporosis. This study focuses on the reliability of a simple parameter like cortical width measured along the mental foramen [mental index (MI)] in assessment of risk of osteoporosis. The aim of this study was to evaluate the usefulness of MI in screening for osteoporosis and to determine whether it correlates with the BMD determined by digital X-ray radiogrammetry (DXR) method.
| Materials and Methods|| |
Seventy-one women living in Hyderabad who were in natural menopause with no known systemic conditions were randomly chosen for the study. The study was approved by the local ethics committee and informed consent was obtained from each subject. Inclusion criterion for the study was women over 60 years of age in natural menopause. Subjects on medications such as glucocorticoids, anticonvulsants, gonadotropin releasing hormone, excessive thyroxin doses, lithium, and calcium supplements were excluded from the study. With the intention of blinding the study, four oral radiologists were recruited as volunteers and were assigned as two observers and two investigators. The personal details and past medical history, along with time elapsed since menopause were recorded and maintained by Observer I. The subjects were coded and the information about the subjects was blinded to both the investigators in order to eliminate information bias. Hand-wrist and panoramic radiographs were taken. All the radiographs were taken following a standardized patient positioning and imaging technique on the Planmeca Proline EC 2002 machine by the same investigator each time (Investigator I). The panoramic image was standardized by correctly determining the patient position, head alignment, and the same investigator took all the radiographs each time. The density and contrast were further assessed by the investigators and any radiographs which were not in the standard range of quality were excluded from the study. After exposure, the image processing and archiving was done using the DurrVistaScan workstation and digital images were obtained.
Calculation of the radiomorphometric MI
All measurements were made in millimeters on the digital image with the inbuilt linear measurement scale in the DurrDBSWIN Vista software (version 3.2). Two sets of measurements were recorded by two investigators in a duration of 1 week for the evaluation of intra-investigator and inter-investigator reliability. When the mental foramen was visible bilaterally, the measurements were made bilaterally and their mean was used as the exposure measure in the analysis. When only one mental foramen was visible, the measurements were done only on that side. The inferior edge of the mental foramen was located and a line parallel to the long axis of the mandible and tangential to the inferior border of the mandible was drawn. A line perpendicular to this tangent intersecting the inferior border of the mental foramen was constructed. The cortical width for the MI was measured along this line. MI was calculated as the width of the cortex along the line perpendicular to the tangent intersecting the inferior border of the mental foramen [Figure 1] and [Figure 2].
|Figure 1: Calculation of mental index (MI) along the perpendicular drawn from the inferior border of the mental foramina to the inferior border of the mandible (h)|
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|Figure 2: Cropped panoramic radiograph showing the MI measurements along the mandibular cortex|
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Calculation of the BMD
The BMD was calculated using the DXR method. The cortical thickness of the three middle metacarpal bones in the hand was measured in a digital X-ray image by a computer using the Pronsco X-posure system software and BMD was expressed as T-score [the number of standard deviations (SD) above or below the mean BMD values for a young healthy adult] and Z-score (the number of SD above or below the mean BMD values for a population of the same age and gender). Based on the 1994 World Health Organization (WHO) report,  the subjects were divided as normal (T-score −1 and above), osteopenic (T-score lower than −1 and greater than −2.5), and osteoporotic (T-score of −2.5 or lower) [Figure 3]. Unblinding of the study was done and all the readings obtained from Investigator I and Investigator II were tabulated for statistical analysis.
| Results|| |
Two sets of readings of MI obtained by the two investigators were tabulated and the average obtained. A magnification factor of 20%, as specified by the manufacturer of the panoramic machine (Planmeca Proline EC 2002), was subtracted from the averages obtained. The final readings of MI, along with the T-score, obtained for normal, osteopenic, and osteoporotic subjects were distributed among the samples [Figure 3]. The statistical analysis was done using SPSS version 14. A P-value of <0.05 was set to be statistically significant. The results were tabulated and graphs obtained. All the values obtained were in millimeters. Mean scores of MI among the three groups of normal, osteopenic, and osteoporotic were obtained and their standard deviations were calculated. Comparison of means between all the groups was done using analysis of variance (ANOVA) followed by post-hoc Tukey's honest significant difference (HSD) test [Table 1]. A correlation of the MI values was done with the study groups using the Pearson correlation coefficient analysis [Table 2].
|Table 2: Correlation of MI with bone mineral density scores (T-score) within groups using Pearson correlation|
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Comparison of MI and BMD
The MI scores were compared with the BMD scores. It was found that in 24 subjects showing normal BMD, the MI ranged from 2.32 to 4.74 with a mean of 3.97. In 30 osteopenic subjects, the MI ranged from 2.48 to 4.86 with a mean of 3.35. In the 17 osteoporotic subjects, the MI ranged from 0.78 to 3.5 with a mean of 2.13. Post-hoc test revealed that normal subjects had a significantly higher MI (P < 0.001) than osteopenic and osteoporotic subjects and, similarly, osteopenic subjects had a significantly higher MI (P < 0.001) than osteoporotic subjects [Figure 4].
|Figure 4: Comparison of mental index (MI) among groups, where the vertical axis represents mean MI and the horizontal axis represents the T-score|
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Correlation of MI with the BMD scores within groups
Correlation of MI was done with the study groups using the Pearson correlation coefficient. It was found that there was a significant (P = 0.01) moderate to strong (MI) correlation at 0.01 level (two-tailed) with the study groups. Within each group also, it was found that MI was moderately correlating with BMD scores in osteopenic (P = 0.05) and osteoporotic (P = 0.05) patients. Hence, the results show that as the BMD increased from osteoporotic to normal, the radiographic measurements also increased [Table 2].
Reliability of MI
In measuring the MI, the intra-investigator reliability ranged from 0.980 to 0.988 and the inter-investigator reliability ranged from 0.964 to 0.980. A strong correlation was found between the measurements of each investigator and the measurements of the two investigators [Table 3].
| Discussion|| |
Osteoporosis is characterized by decrease in BMD and microarchitectural deterioration in bone tissue leading to fractures. An osteoporotic fracture is a fracture of bone caused due to compromised bone strength, and commonly occurs in the vertebral bodies and distal radius, both sites composed predominantly of medullary bone.  According to the US National Osteoporosis Foundation (NOF), bone deterioration is greater in women, especially postmenopausal women, compared to men. Women in their eighth decade have a 10 times greater risk of being osteoporotic than women in their fifth decade.  In women, the risk of developing osteoporotic fractures after the age of 50 years is estimated to be 40-50%, similar to that of coronary heart disease. It has been reported that only one-third of the patients surviving a hip fracture regain their original level of function.  The debilitating effects of osteoporosis may have dramatic outcomes in terms of morbidity, mortality, and cost of health care. It was found that post-menopausal women receiving anti-resorptive drugs obtain a 5-10% increase in BMD which reduces the risk of osteoporotic fractures.  Hence, there is a pressing need to establish effective strategies for early diagnosis of osteoporosis. Various methods have been employed to determine the BMD, which include dual-energy X-ray absorptiometry (DXA and DEXA), quantitative computed tomography (QCT), qualitative ultrasound (QUS), single-photon absorptiometry (SPA), dual-photon absorptiometry (DPA), DXR, and single-energy X-ray absorptiometry (SEXA). DXR is a highly precise BMD measure in which the cortical thickness of the three middle metacarpal bones in the hand is measured in a digital X-ray image and is converted to the forearm BMD through a geometrical operation. Because of its high precision, DXR is the technique of choice used to measure small changes in BMD that occur over time, and hence is more effective in monitoring changes that occur naturally on aging. 
In a dental setting, a panoramic radiograph is commonly taken. Hence, it will be very useful if this radiograph can hint the possibility of the patient being osteoporotic. Although a review of literature has revealed studies indicating that a panoramic radiograph may be one of the tools that can be used to identify individuals with low BMD and high risk of osteoporotic fracture, ,,, the present study focuses on the use of a simple radiomorphometric index (MI) measured on a panoramic image which is easy to calculate and can be done on a routine basis. The study was double blinded and the aforementioned index was calculated and compared in normal, osteopenic, and osteoporotic subjects. To curtail intrinsic errors and observer variability, the present study involved two sets of readings calculated by two different investigators. Inter- and intra-investigator reliability was assessed using the intra-class correlation coefficients. A strong correlation was found between the measurements of each investigator and the measurements of the two investigators. This was in accordance to the results of a study conducted by Yaşşar and Akgünlüü,  in which a strong correlation was found in the intra-examiner measurements. However, inter-examiner reliability was not assessed for the same.
In the present study, it was found that there was a statistically significant difference in the mean scores of MI among normal, osteopenic, and osteoporotic subjects. Normal subjects had significantly higher MI (P < 0.001) than the osteopenic ones and, similarly, the osteopenic subjects had significantly higher MI than the osteoporotic subjects. This was in accordance with the finding of Devlin and Horner.  In a recent Turkish study conducted by Gulsahi et al.,  it was found that the values of MI were significantly lower in increased age group, and they proposed that an MI value of less than 3 mm may be seen as high risk for osteoporosis indicating the need for further advanced osteoporosis investigations. In the present study, a similar finding was observed wherein the MI in osteoporotic subjects was in the range of 0.78-3.5 with a mean of 2.13. Although the conclusion was supported by the large sample size used, the limitation was that no data was collected on age, gender, medical status, and bone densitometry. The advantage of the present study was that data were collected based on age, gender, medical status, and bone dosimetry. Furthermore, the present study was double blinded, wherein two investigators and two observers were used to curtail bias and intrinsic errors, thereby having a high reliability of the index. Bone dosimetry method employed in the present study is a highly precise method and a technique of choice used to measure small changes in BMD that occur over time. 
Obtaining better results is easier when gross changes like width of the inferior border, length of the teeth, etc., are measured than measuring parameters like the morphology of the superior border of the inferior cortex, which depends on the visual perception and entails high examiner variability. Reproducibility of an index is of utmost importance in using it for the assessment of osteoporosis. Hence, our study involved the MI, which is more reproducible in a dental setting. Dutra et al. stressed on the efficacy of MI over other indices as the status of the mandibular dentition does not influence this index. In another study conducted by Bras et al. in the University of Amsterdam, the authors reported that a relatively constant thickness of cortical bone at the mandibular angle following adolescent growth and the decrease in cortical thickness in post-menopausal women suggested that the cortical thickness may be useful as a parameter in determining metabolic bone loss. In a similar type of study conducted by Kribbs  in the University of Washington, mandibular measurements were compared with the measurements of bone mass in the spine and the wrist. Mandibular bone mass was not significantly affected with increase in age, but mandibular bone mass significantly correlated with skeletal bone mass and cortical thickness decreased with age. Correlational analysis in the present study showed that within each group, MI was moderately correlating with BMD scores in osteopenic patients and osteoporotic patients (P = 0.05). Hence, it was found that as BMD increased from osteoporotic to normal, the value of MI also increased. This was in conjunction with the findings of studies conducted by Khojastehpour et al.
Although the study included a highly reproducible index, the reliability of other known indices like Panoramic Mandibular Index (PMI), Gonial Index (GI), and Body Mass Index (BMI) was not assessed in the present study. Furthermore, a larger sample size on a wider stretch of population would aid in determining a cut-off value of the cortical width (MI) to find the stage of osteoporosis in post-menopausal women. This would add momentum to the research in this area and explain why variations in values occurred in some demographic regions.
| Conclusion|| |
The present study compared the diagnostic information obtained from MI calculated on a panoramic image with the BMD in the assessment of osteoporosis and concluded that there was a statistically significant decrease in the cortical width (MI) in the study groups from normal to osteoporotic. The inter- and intra-investigator variability was low. Furthermore, MI correlated significantly with BMD scores. The authors conclude that MI is a simple and reliable radiomorphometric index which can possibly prove as a predictor of osteoporosis in undiagnosed cases, thereby helping in early treatment planning and effective management of the disease.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]