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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 34  |  Issue : 4  |  Page : 452-455

Correlation of the mandibular inferior cortical index and panoramic mandibular index on digital panoramic radiographs with total serum calcium and maximum hand-grip strength in the elderly – A prospective study


RKDF Dental College and Research Centre, Bhopal, MP, India

Date of Submission21-Jul-2021
Date of Decision25-Nov-2022
Date of Acceptance25-Nov-2022
Date of Web Publication09-Dec-2022

Correspondence Address:
Bipasha Das
Senior Lecturer, Department of Oral Medicine and Radiology, RKDF Dental College and Research Centre, Bhopal, MP
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_205_21

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   Abstract 


Introduction: Panoramic radiograph classification can be used in general dental practice to identify the suspected risk of osteoporosis. Objective: The study aimed to compare the values of mandibular inferior cortex (MIC) classification and panoramic mandibular index (PMI) in the digital panoramic radiographs of elderly males and females to investigate whether there was a relationship between the indices and total serum calcium (TSC) and maximum hand-grip strength. Methods: Forty healthy elderly males and females were included in the study. The PMI and MIC were measured using a digital panoramic machine. Their TSC was evaluated, and the maximum hand-grip strength was recorded using a dynamometer. The correlation of the indices with TSC was analyzed to evaluate osteoporotic changes in the mandible. Results: The hand-grip strength was significantly higher in males than in females. The class 2 MIC was significantly higher compared to that in class 1 and class 3. The kappa value of the intraobserver agreement was almost perfect. The mean rank of MIC classification of females was significantly higher than that of males. The correlation among the MIC, PMI, and TSC was statistically significant. Conclusion: The present study showed that the MIC classification might be a better indicator/predictor for detecting early osteoporotic changes in older women.

Keywords: Dental panoramic radiographs, inferior mandibular cortex, maximum hand-grip strength, panoramic mandibular index, total serum calcium


How to cite this article:
Das B, Bagewadi SB. Correlation of the mandibular inferior cortical index and panoramic mandibular index on digital panoramic radiographs with total serum calcium and maximum hand-grip strength in the elderly – A prospective study. J Indian Acad Oral Med Radiol 2022;34:452-5

How to cite this URL:
Das B, Bagewadi SB. Correlation of the mandibular inferior cortical index and panoramic mandibular index on digital panoramic radiographs with total serum calcium and maximum hand-grip strength in the elderly – A prospective study. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2023 Feb 3];34:452-5. Available from: http://www.jiaomr.in/text.asp?2022/34/4/452/363024




   Introduction Top


Osteoporosis is defined as a systemic disease of the bone that is characterized by reduced bone mass and disrupted bone tissue microstructure, which leads to increased bone fragility and fracture risk.[1] The panoramic mandibular index (PMI) is the ratio of the thickness of the mandibular cortex to the distance between the mental foremen and the inferior mandibular cortex.[2] Although many studies have evaluated mandibular radiomorphometric indices [mental index, mandibular inferior cortex (MIC), mandibular cortical index (MCI), PMI, and antegonial index] as indicators of possible osteoporosis in post-menopausal women, few studies[3] have evaluated these measurements in older men. The present study aims to perform radiomorphometric measurements of the mandibular bone on panoramic radiographs. There is a MIC classification by Klemetti et al.,[4] who suggested that the MIC classification can be used to identify females who are at an increased risk of osteoporosis.

Rantanen et al. said that hand-grip strength correlated with the strength of other muscle groups and is thus a good indicator of overall strength.[5] We hypothesized that there might be a relation between the increased erosion of the inferior border of the mandible and the elevated total serum calcium (TSC). Therefore, we conducted a study among the MIC, PMI, maximum hand-grip strength, and TSC to investigate the relationship among these factors.


   Materials and Methods Top


Study sample

The cross-sectional study was conducted on elderly patients visiting the Outpatient Department of Oral Medicine and Radiology, ITS-CDSR, Muradnagar, Ghaziabad, Uttar Pradesh, India, from June to September 2015. Forty patients, both males and females, aged 60–70 years, were included in the study. The total serum calcium, dental digital panoramic radiographs, and maximum hand-grip strength were obtained for all 40 older adults. Patients with the number of teeth more than 15 in the oral cavity were included in the study. Patients who did not want to undergo dental panoramic radiography, those taking any medication that might affect bone metabolism, smokers, presence of any pathology, and completely edentulous jaw were excluded from the study. Images with high technical standards (i.e., appropriate sharpness, density, and contrast) were taken. All participants were informed through written and verbal aspects about the study in local and English languages and written informed consent was taken from all subjects before commencing the study. Our study was by the principles of the Declaration of Helsinki. Ethical clearance from the institutional ethical committee of the ITS Centre for Dental Studies and Research (registration no. ITSCDSR/IIEC// RP/2014/001), Muradnagar, Ghaziabad, Uttar Pradesh, India, was obtained.

Radiographic measurements

The PMI and MIC were measured using a digital Carestream OPG machine using Carestream software in an ideal viewing condition. The researcher was calibrated to make all the measurements. Two readings were taken by the same researcher 15 days apart.

Mandibular inferior cortex (MIC) classification: Measurements of the MIC were determined by observing the mandible distally from the mental foramen on both sides, and the results were divided into three groups (Classes 1–3)[6] [Figure 1]:
Figure 1: MIC classification. Class 1: normal MIC; Class 2: mildly to moderately eroded MIC; Class 3: severely eroded MIC.[4]

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  1. Class 1 (normal cortex): the endosteal margin of the cortex was even and sharp on both sides.
  2. Class 2 (mildly to moderately eroded cortex): the endosteal margin showed semi-lunar defects (lacunar resorption) or appeared to form endosteal cortical residues on one or both sides.
  3. Class 3 (severely eroded cortex): the cortical residues were porous on one or both sides.


Panoramic mandibular index (PMI): The PMI was calculated from panoramic X-ray images by dividing the height of the inferior mandibular cortex by the distance from the lower border of the mandible to the inferior edge of the mental foramen. The thickness of the mandibular cortex was divided by the distance between the mental supervisors and the inferior mandibular cortex to obtain the PMI [Figure 2].[7]
Figure 2: Measurement of the PMI (a/b).[7]

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Estimation of the serum calcium level

Total serum calcium (TSC) was measured at the pathology laboratory of Surya Hospital, ITS-CDSR, Muradnagar, Ghaziabad, Uttar Pradesh.

Measurement of maximum hand-grip strength

The maximum hand-grip strength was measured using a hand dynamometer (BaselineR) at the Department of Physiotherapy, ITS-CDSR, in two trials for both the dominant and non-dominant hands. The score obtained was the best of the trials for both grip strengths.

Sample size estimation

The sample size was calculated using the master 2.0 software. The power of the study was taken to be 80%, and a confidence interval (CI) of 95% was taken. The sample size was estimated to be a minimum of 35 patients. We took a sample size of 40 patients.

Statistical analysis

The data were entered into Microsoft Excel and analyzed using SPSS package 26.0 for relevant statistical comparisons. The results were presented in the form of tables and graphs. Descriptive statistics were calculated by mean, standard deviation, frequencies, and percentages for the continuous variables. Categorical variables were summarized as frequencies and percentages. Inferential statistics was analyzed using the Chi-square test for the categorical variables, and the Mann–Whitney U test was used to compare mean ranks between the two groups. The kappa value was used to examine the degree of agreement between two observers.The level of statistical significance was set at a P value less than or equal to 0.05.


   Results Top


A total of 40 patients (20 males and 20 females with a mean age of 62.70 and 62.20 years, respectively) were enrolled in the study. The mean hand-grip strengths of males and females were 65 and 52.25 pounds, respectively. The hand-grip strength was significantly higher in males than females. The TSC levels for both males and females were within the normal range (8.4–10.5 mg/dl). The class 2 MIC was significantly higher in males and females compared to class 1 and class 3 [Figure 3]. Based on the guidelines of the interpretation of kappa statistics, the following categories were considered: 0.00 (poor), 0.00–0.20 (slight), 0.21–0.40 (fair), 0.41–0.60 (moderate), 0.61–0.80 (substantial), and 0.81–1.00 (almost perfect). The kappa value of the intraobserver agreement was in the category of almost perfect. By the Mann–Whitney U test, the mean rank of MIC classification of females was significantly higher than that of males. The correlation among MIC, PMI, and TSC was statistically significant [Table 1] and [Table 2].
Figure 3: Correlation between the MIC and gender. Class 1 MIC is more in males than females, class 2 MIC is equal in both males and females, and class 3 MIC is only seen in females

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Table 1: Intraobserver agreement is in the category of almost perfect

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Table 2: Comparison of MIC classification between males and females; measurement of the MIC is more in females as compared to males

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   Discussion Top


Early diagnosis of osteoporosis is important to reduce fracture risk and to initiate early treatment. Panoramic radiographs are used extensively in dentistry and allow the study and evaluation of the maxillary and mandibular bone structure, along with teeth. It has been reported that calcium absorption decreases with age. This could be due to a decline in serum calcitriol, possibly because of declining renal function, a decline in the gastrointestinal response to calcitriol, declining exposure to sunlight, or a decline in the capacity of the skin to synthesize vitamins. This mechanism results in inadequate bone calcium absorption, whereas the TSC becomes higher. Other investigators have reported that a lack of estrogen in post-menopausal women prevents the absorption and utilization of calcium and is the single most important factor in the development of osteoporosis in older women. To reflect bone metabolism, we used PMI and MIC conditions on a series of dental panoramic radiographs and investigated the relationship between TSC and maximum hand-grip strength.[8]

In this study, a relationship was found in females but not in males. In our opinion, the potential for an interaction between hormonal activity, diet, and physical activity to influence bone metabolism is likely to be important. The aging process plays a role in declining the speed of bone formation; therefore, decreasing the speed of bone resorption by changing the diet and lifestyle is becoming the main option in elderly people. In young adults, when the skeleton is mineralized and there is great demand for calcium for bone growth, the calcium requirement will result in lower TSC.[9]

Rantanen et al.[5] said that hand-grip strength correlated with the strength of other muscle groups and is thus a good indicator of overall strength. In old age, decreased muscle strength predisposes people to functional limitations and disability. Brown et al.[10] said that reduced lower maximal isometric knee extensor strength has been associated with a reduction in gait speed, balance, stair climbing ability, and getting up from seated positions. Consequently, the MIC condition might be used as a sign of a decline in physical activity and to advise patients to improve muscle strength through physical exercise at all ages. Our study found that increased erosion of the inferior border of the mandible is useful for predicting when there is a change in the metabolism of TSC in blood and also only in females. The detection of class 2 MIC classification in females is becoming more important for preventing further bone loss. Moreover, dentists should refer to a medical professional for females with class 3 MIC classification or with a change to class 3 MIC classification. Therefore, these findings suggest that dentists should be aware and should further examine females with class 3 MIC classification to prevent fractures related to bone loss in patients.[8] Klemetti et al.[4] evaluated the MCI, which is also known by the first author's name. They suggested that a thin or eroded inferior cortex of the mandible detected on dental panoramic radiographs, an indicator of alterations of the mandible, is useful for identifying post-menopausal women with undetected low skeletal bone mineral density or osteoporosis. Duncea and Khosla et al.[11],[12] have also found that the PMI value is lower in women suffering from osteoporosis. The PMI can be used for orientation purposes in distinguishing osteoporotic patients from healthy ones.

Limitations: The sample size of the study group was small, that is, 40 patients. We found a small positive correlation between PMI and MIC conditions and TSC levels. Furthermore, we did not measure bone metabolisms such as bone formation and resorption markers. It will be important to consider all these factors in further studies.

Future Prospects: Although this study on calcium function refers to increased erosion of the inferior border of the mandible as a decline of bodily functions with advancing age, we did not precisely measure the calcium intake, absorption, and excretion in blood; the mechanism of elevated TSC still needs to be studied. Therefore further studies with larger sample sizes using bone densitometry should be carried out. However, this study reiterates the role of an oral radiologist in the early detection of osteoporosis.


   Conclusion Top


The present study showed that the inferior mandibular cortex (MIC) classification might be a better indicator/predictor for the detection of early osteoporotic changes in older women. Increased erosion of the inferior border of the mandible was useful for predicting when there was a change in the metabolism of TSC in blood. The detection of class 2 MIC classification in females is becoming more important for preventing further bone loss.

Key message

This study reiterates the role of an oral radiologist in the early detection of osteoporosis

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Lee BD, White SC. Age and trabecular features of alveolar bone associated with osteoporosis. Oral Surg Oral Med Oral Pathol Oral Radiol Oral Endod 2005;100:92–8.  Back to cited text no. 1
    
2.
Melton LJ 3rd. The prevalence of osteoporosis: Gender and racial comparison. Calcif Tissue Int 2001;69:179–81.  Back to cited text no. 2
    
3.
Dagistan S, Bilge OM. Comparison of antegonial index, mental index, panoramic mandibular index and mandibular cortical index values in the panoramic radiographs of normal males and male patients with osteoporosis. Dentomaxillofac Radiol 2010;39:290–4.  Back to cited text no. 3
    
4.
Klemetti E, Kolmakov S, Kröger H. Pantomography in assessment of the osteoporosis risk group. Scand J Dent Res 1994; 102:68–72.  Back to cited text no. 4
    
5.
Rantanen T, Guralnik JM, Foley D, Masaki K, Leveille S, Curb JD, et al. Midlife hand grip strength as a predictor of old age disability. J Am Med Assoc 1999;281:558–60.  Back to cited text no. 5
    
6.
Dagistan S, Bilge OM. Comparison of antegonial index, mental index, panoramic mandibular index and mandibular cortical index values in the panoramic radiographs of normal males and male patients with osteoporosis. Dentomaxillofac Radiol 2010;39:290–4.  Back to cited text no. 6
    
7.
Hastar E, Yilmaz HH, Orhan H. Evaluation of mental index, mandibular cortical index and panoramic mandibular index on dental panoramic radiographs in the elderly. Eur J Dent 2011;5:60-7.  Back to cited text no. 7
    
8.
Kiswanjaya B, Yoshihara A, Miyazaki H. Mandibular inferior cortex erosion as a sign of elevated total serum calcium in elderly people: A 9-year follow-up study. Dentomaxillofac Radiol 2014;43:1-7.  Back to cited text no. 8
    
9.
Abrams SA, Griffin IJ, Hawthorne KM, Gunn SK, Gundberg CM, Carpenter TO. Relationships among vitamin D levels, parathyroid hormone and calcium absorption in young adolescents. J Clin Endocrinol Metab 2005;90:5576–81.  Back to cited text no. 9
    
10.
Brown M, Sinacore DR, Host HH. The relationship of strength to function in the older adult. J Gerontol 1995;50:55–9.  Back to cited text no. 10
    
11.
Duncea I, Pop A, Georgescu CE. The relationship between osteoporosis and the panoramic mandibular index. HVM Bioflux 2013;5:14-8.  Back to cited text no. 11
    
12.
Khosla S, Atkinson EJ, Melton JL III, Riggs BL. Effects of age and estrogen status on serum parathyroid hormone levels and biochemical markers of bone turnover in women: A populationbased study. J Clin Endocrinol Metab 1997;82:1522–7.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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