EVALUATION OF RADIOMORPHOMETRIC INDICES OF NORMAL AND POSTMENOPAUSAL OSTEOPOROTIC FEMALE PATIENTS BY PANORAMIC RADIOGRAPHS.

Purpose: To evaluate the significance of radiomorphometric indices, Panoramic Mandibular Index (PMI), Mandibular Cortical Index (MCI) and Antegonial index (AI) of the mandibular bone on panoramic radiographs and co-related with bone mineral density (BMD) for the diagnosis of postmenopausal osteoporosis. Methedology: Group ‘A’- 20 premenopausal women, Age range 30-55 years . Group ‘B’- 20 postmenopausal women, Age range 57- 75 years for the study were selected through detailed case history,

BMD scans has been done for AP lumbar spine (L1-L4), Right and Left femur neck. Analysis of osteoporosis by Tscore was done on the basis of WHO classification 6 . The World Health Organization (WHO) criteria for defining osteoporosis, osteopenia and normal is as follows : 1. Normal -BMD for young healthy adult ( T ≥ -1.0) 2. Osteopenia -BMD for osteopenia ( T score between -1.0 and -2.5 ) 3. Osteoporosis -BMD ≤ 2.5 SD Clinical Protocol Before scanning patient Before patients come in for their scans, they should be informed of the following issues: 1. It was ensured that patients can tolerate lying flat on their back and keeping still for at least 10 min. 2. The weight of subjects was determined. All DXA systems can scan patients up to 300 lb (136 kg). If they are over 300 lb, they may need to have an alternative bone density or body composition test performed. 3. To check any medical imaging procedure recently if they have received contrast, such as barium or gadolinium, they should be scheduled two weeks after contrast was administered. 4. In premenopausal patients, it was asked that is there any possibility that they might be pregnant. 5. Calcium tablets should not be taken in the 24 h before the examination. 6. Patients must wear comfortable, loose fitting clothes, such as a sweat suit

Radiographic Procedure
All Group 'A' and Group 'B' were drapped with lead apron and thyroid collar. Panoramic radiographs were taken for all patients who gave informed consent at time of DXA measurement with panoramic X-ray machine (Advapex 2000 the Xtropan imaging system version 2000). In order to achieve a standard, the radiographs were obtained by a single examiner at 3-6mA and 18 sec the voltage varied between 55 -80kVp depending on the age, sex and built of the patient. Patients were positioned in the dental panoramic machine in such a way that vertical line produced by the machine was aligned with the patient's saggital plane, with the horizontal line (Frankfort plane) parallel to the floor.
After the exposure, all the images were recorded with the help of a printer (Fujifilm capsula plus 4000 dry pix). Later all the radiographs were submitted for measurement of radiomorphometric indices by two observers independently.

Assessment of Radiographic interpretation
First each observer traced the structures of interest on transparencies placed on the radiographs. Measurements were bilaterally performed with the help of vernier caliper and scale by using magnifying lens on the transparencies by the same observer.
A second observer performed the same measurement at different time, without any knowledge about the first observer's readings.
All measurements were made with both the observers blinded to the reference osteoporotic diagnosis. All the measurements were aimed at obtaining the following radiomorphometric indices :

Panoramic Mandibular Index (PMI) -
The PMI is the ratio of the thickness of the mandibular cortex to the distance between the mental foramen and the inferior mandibular cortex bilaterally 7 . (Fig-1

Interobserver Analysis
In the present study, Inter-observer agreement for of PMI and AI (continuous data) was evaluated by Pearson correlation coefficient and the correlation between the observers for PMI (post-menopausal: r=0.917, pre-Menopausal: r = 0.712) and AI (post-menopausal: r=0.936, pre-Menopausal: r = 0.860) agreements were interpreted as very strong agreement.
Inter-observer agreement for MCI (ordinal data) was evaluated by weighted kappa. The agreement between the observers for MCI (post-menopausal: k=1.000, pre-Menopausal: K = 1.000) was found to be statistically significant

Panoramic Mandibular Index (PMI)
Panoramic Mandibular Index (PMI) < 0.30mm considered as osteoporotic finding . So, here in this study mean PMI is 0.29mm and 0.34mm for post menopausal and pre menopausal females respectively and statistically significant difference was observed between the groups (p<0.01).

Antegonial Index
Antegonial Index (AI) < 3.2 mm considered as osteoporotic finding. In the present study mean AI 2.96mm and 3.58 for post menopausal and pre menopausal females respectively and statistically significant difference was observed between the groups (p <0.001)

Mandibular Cortical Index (MCI)
1. Mandibular Cortical Index (MCI) C 1 stands for Normal , C 2 stand for osteopenia and C 3 stands for osteoporosis 5 2. In the present study % of MCI in class C 1 is 20% and 80% for post menopausal and pre menopausal females respectively 3. Class C 2 is 55% and 15% for post menopausal and pre menopausal females respectively signifies presence of osteopenia 4. Class C 3 is 25% and 5% for post menopausal and pre menopausal females respectively signifies presence of osteoporosis.

100-Specificity (False Positive)
Klemetti E et al (1993) 9 indicated that particularly the BMD of the buccal part of the mandibular cortex, distally from the foramen mentale, correlates remarkably well with that of the femoral collum which, when BMDs are compared, reflect the general osteoporosis status of the human body. In far resorbed mandibles, the lingual cortex contains significantly less mineral than does the buccal layer and, in that respect, begins to show a correlation with the spongiosa in the same region.
Taguchi A et al (1995) 10 investigated the possibility of using oral signs as an indicator of postmenopausal osteoporosis. The number of teeth present, mandibular cortical width at the mental region (MCW), the degree of mandibular alveolar bone resorption and morphologic classification of mandibular inferior cortex MIC grade (acc to klemetti E et al 5 ) were evaluated on panoramic radiographs as oral signs. They concluded that these oral signs revealed a significant relation of age and number of teeth with the fracture status of women from 50 -70 years of age. Calculation of probability of fracture were found to be useful in screening for latent osteoporosis.
Payne JB et (1999) 11 reported that estrogen deficient postmenopausal women displayed a loss in alveolar bone density using CADIA (Computer assisted densitometric image analysis) Osteoporotic / osteopenic women exhibited a higher frequency of alveolar bone height loss and crestal and subcrestal density loss relative to women with normal BMD. According to the study estrogen deficiency was associated with increased frequency of alveolar bone crestal density loss in osteoporotic/osteopenic women and in the overall study population. Osteoporosis/osteopenia and estrogen deficiency were risk factors for alveolar bone density loss in postmenopausal women. However, the study conducted by Byung Do Lee et al (2005) 8 shows CART (classification and regression tree) analysis which founds that alveolar bone density was less useful than age or strut measures for subjects classification. 12 examined the radiomorphometric indices (GI Gonion index, MI Mental Index, MCI , PMI and AI) and their relationship with age, dentition and social class on panoramic radiographs in British female population and they concluded that BMD differs between ethnic groups so in comparison to white women , black women have a higher peak bone mass so, slower rate of bone loss from femur and spine. All indices demonstrated negative correlation with age and a significant difference between the younger and older age groups. But it was required to test the diagnostic validity of such method relating DXA measurement. They found that dentition has no measurable influence upon MI or PMI. 13 established the criterion value of BMD for the diagnosis of osteoporosis and to estimate the prevalence rate of osteoporosis in Japanese women. They concluded that prevalence rate of osteoporosis at the femoral neck was suggested to be lower in Japanese than in Caucasians, which may account for a lower incidence rate of hip fracture in Japanese women. 14 conducted that MI, PMI, AI and GI (Gonion Index) showed a general downward trend with age for the both sexes until 75 years of age for female as compared to male and significantly higher incidence of C3 existed in the oldest group of females. 15 demonstrated that the sensitivity and specificity for using panoramic radiographic measurements do not lend themselves to satisfactory diagnosis of osteopenia and osteoporosis. They concluded that these measurements (AI, GI and MI) might be useful as a method of risk assessment when combined with other factors. 16 identified that it is possible to intercept the progress of osteoporosis through early warning and treatment and they also concluded that the thickness of mandibular angular cortex can be used as a index for bone resorption. Hren N (2005) 17 determined a simple method of common DPT (dental panoramic tomograms) analysis that could represent a simple, inexpensive and readily available screening tool for osteoporosis. Mandibular atrophy was assessed by six anatomic indexes. They concluded RBD ( Relative Bone Density) of the mandible was statistically significantly lower in the osteoporotic group of women. 5 were taken 100 women aged 50-84 years who also had BMD assessment of the lumbar spine and femoral neck by dual-energy x-ray absorptiometry. The panoramic images were examined twice by 4 observers to evaluate the thickness of the mandibular inferior cortex. They concluded that simple visual estimation of the mandibular inferior cortex on panoramic radiographs may be useful for identifying postmenopausal women with low BMD.

Lee K et al (2005)
Dargent-Molina P, Piault S, Bréart G (2005) 18 on the basis of EPIDOS (Epidemiology of osteoporosis) , which was a prospective multicenter study of risk factors for hip fractures concluded that the triage strategy were significantly more sensitive than systematic BMD screening (51 versus 35%) and would require many fewer BMD examinations .Compared with current recommendations, triage would identify fewer women (20 versus 28%) but at a significantly higher average risk of hip fracture. It can be a useful clinical tool for selecting elderly women for treatment or bone densitometry. 19 concluded using a Classification and regression tree (CART) that clinical information is as useful as panoramic radiographic information for identifying subjects having low bone mass, and dentists have sufficient clinical and radiographic information to play a useful role in screening for individuals with osteoporosis. 20 concluded that assessment of mandibular cortex patterns is a reliable method to exclude osteopenia/osteoporosis. They indicated that the dentist should screen patients and refer those with positive findings for further assessment for the potential diagnosis of osteopenia/osteoporosis, and also use the strong negative finding (KI category <2) is highly predictive of the absence of osteopenia/osteoporosis as defined by the DXA measurements. 21 concluded that severe erosions on the endosteal margin of the mandible are seen more frequently in women over 60 years in age and mean mandibular cortical width values decrease significantly in women of the same age group. 22 concluded that MIC classification may be useful for screening patients for the possibility of osteoporosis by measuring bone stiffness with ultrasound bone densitometry in elderly Japanese people.

Kiswanjaya B et al (2010)
Devi Y B K, Nagaraju R , Ravleen N (2011) 1 concluded that elderly women with PMI < 0.25 mm in the panoramic radiographs should be referred for advanced osteoporosis investigation. Although radio morphometric indices are regarded as an ancillary method for the diagnosis of osteoporosis on panoramic radiographs, they should be a routine procedure in dental examination and dentists may be able to refer postmenopausal women younger than 65 years for bone densitometry on the basis of incidental findings on dental panoramic radiographs. They stated that the panoramic radiograph plays a vital role in identifying postmenopausal women with undetected osteoporosis. 23 study the role of panoramic radiograph in detecting reliability and accuracy of MCI to diagnose osteopenia and osteoporosis. They concluded that the variations in the width and shape of the inferior cortical edge of the mandible are seen clearly on OPG. Determination of Klemetti index was easy and simple screening method where dentists use an X ray made for other reasons without the patient being additionally burdened radiologically and financially. 24 concluded that a positive correlation between the CI findings and the presence or absence of osteoporosis as defined by the DVO (German Osteology Organization). Patients were assessed CI of the category "severe" on non-standardised panoramic radiographs have a higher risk of having systemic osteoporosis and suggested that they should be referred to a DXA examination to further verify the diagnosis. 25 tested a new method of dental panoramic tomogram (DPT) analysis to show the differences of mandibular bone volume and relative bone density (RBD) in order to detect osteoporosis. DPTs were analyzed using an original method resulting in anatomic and RBD indexes. Average values of RBD indexes were statistically significantly different between O (Osteoporotic) and N(Normal) and also between o (osteopenic) and N(Normal) . Important differences regarding RBD were confirmed using a new and original method of common DPT analysis. They concluded that this method could serve as a screening tool for osteoporosis Sharon H. Chou et al (2014) 26 indicated that in a multiracial referral population heel BMD correlates significantly with hip BMD and that the ability of heel BMD to predict central osteoporosis as well as presence of vertebral