| Abstract|| |
Context: In most women bone mass reaches its peak in the third decade of life and declines thereafter with the onset of menopause and might lead to osteoporosis. Osteoporosis may result in reduced jaw bone mass and alterations of the mandibular structure. Qualitative and quantitative indices have been used for panoramic radiographs to assess the alveolar bone quality.
Aims: The purpose of this study was to compare the alveolar bone quality of premenopausal and postmenopausal women using the panoramic mandibular index (PMI). This study also aimed to estimate the levels of serum calcium in premenopausal and postmenopausal women.
Settings and Design: Single centre case control study.
Materials and Methods: A total of 30 patients were divided into three groups of ten each - the healthy group, control group, and study group. Alveolar bone mass was evaluated by the PMI. Serum calcium was also assessed for all the patients.
Statistical analysis used: The results obtained were subjected to statistical analysis by one-way analysis of variance using Statistical Software SPSS version 17, Tukey test for comparision, Pearson's correlation coefficient was employed.
Results: Premenopausal women had the highest values for alveolar cortical bone mass as recorded by the PMI, followed by postmenopausal women with a healthy periodontium. The lowest values were recorded in the group of postmenopausal women with chronic generalized periodontitis. Similar results were found for serum calcium values.
Conclusion: Postmenopausal women exhibit a reduced alveolar bone mass and lowered levels of serum total calcium with the increasing age. These changes may be useful indicators for low skeletal bone mineral density or osteoporosis.
Keywords: Alveolar bone mass, menopause, panoramic mandibular index, serum calcium
|How to cite this article:|
Ramesh A, Mahajan K, Thomas B, Shenoy N, Bhandary R. Alveolar bone mass in pre- and postmenopausal women with serum calcium as a marker: A comparative study. Indian J Dent Res 2011;22:878
Growth and development during the period of infancy and childhood depends upon mineralization of the skeleton, which achieves peak bone mass during early adulthood.  This optimal bone mass varies between men and women. In most women bone mass reaches its peak in the third decade of life and declines thereafter. This decline in bone mass is accelerated with the onset of menopause and might lead to excessive bone resorption and ultimately, osteoporosis.  Osteoporosis is defined as "a disease characterized by low bone-mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk." 
|How to cite this URL:|
Ramesh A, Mahajan K, Thomas B, Shenoy N, Bhandary R. Alveolar bone mass in pre- and postmenopausal women with serum calcium as a marker: A comparative study. Indian J Dent Res [serial online] 2011 [cited 2019 Aug 21];22:878. Available from: http://www.ijdr.in/text.asp?2011/22/6/878/94667
Previous research has shown that osteoporosis may result in reduced jaw bone mass, as well as alterations of the mandibular structure.  This bone loss occurs most rapidly in the early postmenopausal period and subsequently begins to level off by 6 year postmenopause.  Skeletal as well as alveolar (jaw) bone loss may be explained by the lack of estrogen production in postmenopausal women. 
The gold standard procedure for assessment of bone mineral density is the dual energy X-ray absorptiometry (DXA, formerly DEXA).  However, such a scan is impossible to use in all situations due to limitations of availability and economy. Qualitative and quantitative indices such as the mandibular cortical index (MCI), mental index (MI), and the panoramic mandibular index (PMI) have been used for panoramic radiographs to assess the alveolar bone quality and to observe signs of resorption and osteoporosis. , Cortical height on radiographs and mineral density seems to follow a similar pattern as seen in the general mineral status of the skeleton. 
Along with its effect on bone density, changes occurring at menopause have shown to affect the levels of serum calcium. 
The purpose of this study was to compare the alveolar bone quality of premenopausal and postmenopausal women using the PMI. This study also aimed to estimate the levels of serum calcium in premenopausal and postmenopausal women to obtain direct information of the bone metabolism. Finally, an attempt was also made to determine the effects of alveolar bone loss on serum calcium levels.
| Materials and Methods|| |
0Female patients in the age group of 35-55 years were selected for the study after having signed informed consents.
A total of 30 patients were selected and divided into three groups of ten each:
Group A - Healthy group (premenopausal women with healthy periodontium).
Group B - Control group (postmenopausal women with healthy periodontium).
Group C - Study group (postmenopausal women suffering from periodontitis).
Criteria for subject selection are as follows:
- Women in good general health, not suffering from any systemic disorder or condition were selected for the study.
- Postmenopausal women within 5 years of menopause were chosen for the control and study groups.
- Women suffering from moderate chronic periodontitis (3 to 4 mm of clinical attachment loss) or severe chronic periodontitis (>5 mm clinical attachment loss) were enrolled in the study group.
- Subjects taking estrogen, corticosteroids, or any other therapy or suffering from parathyroid dysfunction.
- Paget's disease or any other disorder likely to affect calcium metabolism.
- Subjects on drugs that can cause increased measurements in calcium levels including calcium salts (eg, nutritional supplements or antacids), vitamin D, lithium, thiazide diuretics, and thyroxine.
- Tobacco users.
- A detailed menstrual history (including years since menopause) was recorded.
- Clinical attachment loss was measured using William's periodontal probe.
- Calculation of PMI to assess alveolar bone quality (using the method described by Benson et al. 1991).
- Panoramic radiographs were taken for all the subjects using the same Orthopantomograph (Planmeca Proline, Planmeca ov, Helsinki, Finland).
- Bilateral measurements of the distances between the inferior border of the mandible and superior and inferior margins of the mental foramen were made and mean was calculated.
- The index was calculated as a ratio of the cortical thickness to the relatively constant distance between the mental foramen and the inferior mandibular border. 
- A single trained observer measured PMI to ensure the reliability of the measurements and avoid interobserver variability.
Evaluation of serum calcium levels
Five milliliter of blood sample was drawn from the subject through disposable syringe and transferred to a centrifuge tube. Blood sample was allowed to stay in the centrifuge tube undisturbed for 30 min. It was then centrifuged, serum separated and sent for biochemical analysis of serum calcium levels.
The results obtained were tabulated and subjected to statistical analysis by one-way analysis of variance (ANOVA) using Statistical Software SPSS version 17. The data were expressed as mean and standard deviation. Since the results of the one-way ANOVA were significant, an additional test of significance-Tukey test for multiple comparisons was performed to analyze the relationship between alveolar bone mass and serum calcium amongst the three groups. P values were considered to be statistically significant (P<0.0005).
To assess the correlation between alveolar bone mass and serum calcium levels, the Pearson's correlation coefficient was employed.
| Results|| |
Alveolar bone quality as measured by PMI
The results of the one-way ANOVA showed a statistically significant difference (between Group A (premenopausal women with healthy periodontium) and group C (postmenopausal women with periodontitis) as well as between group B (postmenopausal women with healthy periodontium) and group C with a mean value of 0.32080 and standard deviation of 0.045385 [Table 1].
The Tukey test of significance revealed a highly statistically significant difference between group A and group C and between group B and group C (P<0.0005) as depicted by [Table 2] and [Figure 1].
|Figure 1: Comparison of alveolar bone mass as measured by PMI between groups A, B, and C|
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The results of the one-way ANOVA showed a statistically significant difference between Group A (premenopausal women with healthy periodontium) and group C (postmenopausal women with periodontitis) as well as between group B (postmenopausal women with healthy periodontium) and group C with a mean value of 8.307 and standard deviation of 1.0504 [Table 3].
|Table 3: One-way ANOVA for serum calcium (mg/dl) between groups A, B, and C|
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The Tukey test of significance revealed a highly significant difference between group A and group C and between group B and group C (P<0.0005) as depicted by [Table 4] and [Figure 2].
|Table 4: Tukey test of significance for serum calcium (mg/dl) between groups A, B, and C|
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Correlation between alveolar bone mass and serum calcium
Pearson's correlation coefficient did not reveal any statistically significant relationship between alveolar bone mass and serum calcium. A mildly positive correlation was found between alveolar bone mass and serum calcium for postmenopausal women with healthy periodontium (Group B), whereas an inverse correlation was found between values for PMI and serum calcium for groups A and C [Table 5], [Table 6] and [Table 7]. [Table 8] depicts values for PMI and serum calcium levels for groups A, B and C.
|Table 5: Correlation between PMI and serum calcium (mg/dl) within Group A|
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|Table 6: Correlation between PMI and serum calcium (mg/dl) within Group A|
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|Table 7: Correlation between PMI and serum calcium (mg/dl) within Group A|
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| Discussion|| |
This study provides useful data regarding alveolar bone mass and quality in pre- and postmenopausal women.
In our study, premenopausal women had the highest values for alveolar cortical bone mass as recorded by the PMI, followed by postmenopausal women with a healthy periodontium. The lowest values were recorded in the group of postmenopausal women with chronic generalized periodontitis. This indicates a loss of bone mineral density and alveolar bone height in postmenopausal women. These findings are consistent with those of Payne et al.  who studied the longitudinal effect on alveolar bone levels in postmenopausal women.
This deterioration of alveolar bone quality can have several implications for dentistry in general and the field of periodontology and implantology in particular. Loss of alveolar bone has been associated with increased tooth mobility and tooth loss in several studies. For example, Taguchi and associates found a positive correlation between decreased mandibular bone density and tooth loss among elderly women. , In a 1996 study of 189 healthy postmenopausal women, Krall, Garcia, Dawson-Hughes and associates found that "normal" bone loss (1% per year) was significantly associated with increased tooth loss. 
Panoramic radiographs are a useful tool for the diagnosis of osteoporosis and for detecting a high risk of osteoporotic fractures. PMI has been used as a morphometric tool for assessing osteoporosis status by different researchers. , The recent studies in the literature , on PMI values have been performed mostly on women. On an average, the results of these literatures reveal PMI values between 0.31-0.38 for women. In this study, the mean PMI value for premenopausal women was 0.34 and that for postmenopausal women was 0.32.
Serum calcium levels for the subjects in our study followed a pattern similar to that for alveolar bone mass/PMI values. The highest levels were present in premenopausal women followed by postmenopausal women with a healthy periodontium. The lowest levels for serum calcium were recorded in the group of postmenopausal women with chronic generalized periodontitis. Similar results were reported by Sokoll et al.  who concluded that serum total calcium declined with age within the pre- and postmenopausal groups and establishing that menopause and age affect serum total but not ionized calcium. These findings may have future implications for research regarding the use of serum calcium levels as a risk indicator for skeletal osteoporosis in perimenopausal women.
Although this study did not attempt to correlate alveolar bone mass with skeletal bone mineral density, a number of authors have concluded that a larger alveolar bone loss (ABL) of the mandible may be associated with lower skeletal BMD or osteoporosis in postmenopausal women. , Several studies suggest that mandibular cortical width detected on panoramic radiographs may be useful for identifying postmenopausal women with low-skeletal BMD or osteoporosis. ,, Recent study results  reveal that patients with the thinnest mandibular cortices (≤3 mm) should be referred for further osteoporosis investigation because it is this group that has the highest likelihood of osteoporosis. Thus, the findings of this study may be used as a means to develop a screening system for early detection of osteoporosis.
One of the limitations of our study was the small sample size that was insufficient for the correlation coefficient to be determined between alveolar bone mass and serum calcium levels. Thus, these results cannot be used to generalize the results to the entire population. Further research with a larger sample size may contribute to our knowledge of serum calcium as a marker for the changes in bone metabolism occurring during menopause. The dental status (tooth loss/extraction) was not taken into account as the PMI is not affected by extractions or tooth loss. , A second limitation is that we did not estimate oral bone height of both jaws, only of the mandible. This may not provide an accurate assessment of alveolar bone levels.
| Conclusion|| |
Postmenopausal women exhibit a reduced alveolar bone mass and lowered levels of serum calcium with diminishing age. These changes may be useful indicators for low skeletal bone mineral density or osteoporosis.
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Department of Periodontics, A.B. Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]