Radiomorphometric indices as indicator in osteoporosis-A digital panaromic study

Introduction

Osteoporosis is a growing health problem recognized in both developed and developing countries. It is associated with substantial morbidity and socio-economic burden worldwide.1 Osteoporosis is considered to be a silent disease that entails significant social and economic burdens. So, there has been a growing interest in the diagnosis and oral signs of osteoporosis recently2

Bone loss occurring with age is a commonly observed phenomenon in humans. It affects both females and males, but it is increased in postmenopausal females. Women suffer from rapid decline of bone mass during the first 5–10 years after menopause, while later the decrease stabilises at a lower rate. In men, bone loss starts later and progresses more slowly than in women.3 This loss of bone in both men and women lead to a more porous bone leading to a condition called osteoporosis. In 30 % to 50 % of women and 15%–30% of men, osteoporosis-related fractures can occur in their lifetime.1

Many bone-mass measuring techniques have been advocated to assess the changes which include dual X-ray energy absorptiometry (DXA), quantitative computed tomography (QCT) and neutron activation analysis with DXA being considered as gold standard. However, they are increased treatment cost and involve expensive equipment. As osteoporosis is related to considerable mortality and increasingly higher costs of health care, screening for osteoporosis particularly in high-risk populations is required. With the above background the present study is intended to analyse the radiomorphometric indices of mandible using digital panoramic radiographs.4, 5

Materials and Methods

Three hundred patients were randomly taken for study aged between 21-70 years the patients were equally divided into males & females & each of this group were further subdivided into 5 age groups with a 10-year interval, these patients were subjected to panaromic radiograph using Sirona Orthophos XG 5 DS/ Ceph digital OPG machine with standard exposure parameters after obtaining the institutional ethical clearance, the patients were equally divided into males & females & each of this group were further subdivided into 5 age groups with a 10-year interval. The measurements were made using the SIDEXIS software considering the magnification factor of the equipment. All the indices and mean were measured and calculated respectively for right and left sides of the mandible after considering the inclusion and exclusion criteria. The observer were blinded for the age and gender of the patient while performing the measurements. Following radiomorphometric indices were measured on right and left sides:

C1 — Endosteal margin of the cortex is even and sharp on both sides.

The measurements were repeated after 1 month by the same observer. Also, the measurements were made by a second observer. At least 20 % of the radiographs were assessed for inter & intra observer reliability.

Graph 1

Comparison of MCI in Relation to age in years

Graph 2

Comparison of age in years in relation to dentition

Results

The relevant demographic data including name, age, gender and patient identification number were recorded for each selected image in a specially designed proforma. The subject’s informed consent was obtained after explaining of the general nature of the study. The radiomorphometric indices were recorded as described in the methodology. The maxillary and mandibular dentition was recorded using a simple classification system (third molars not included): full dentition, partial dentition (missing any teeth) and edentulous as described by A Gulsahi et al. 15 All measurements were made separately on the right and left mandibular sides and their means were calculated considering the magnification factor of the equipment which was 19%. The obtained data was then subjected to statistical analysis 20% of the radiographs were assessed for inter and intraobserver reliability after a month and was found to be statistically insignificant with p value < 0.8. Dentition status of patients studied the study population consisted of 49.3% of dentate individuals, 47.7% were partially edentulous and 3% were completely edentulous. (Table 1).

Discussion

In humans, bone is constantly resorbed and formed by the process known as remodelling. Bone loss occurring with age is a commonly observed phenomenon. From 3rd to 5th decade, the amount of bone formed approximately equals the amount resorbed irrespective of the gender. With aging, the amount of bone resorbed by osteoclasts is not fully restored with bone deposited by osteoclasts and this imbalance leads to loss of bone mass and strength.9 Estrogen plays a pivotal role in maintaining positive balance in bone remodelling by supporting osteoblasts and preventing bone resorption by suppressing osteoclast formation, stimulating osteoclast apoptosis, and counteracting oxidative stress.10

Peak bone mass is achieved during early adulthood but varies between men and women. Both men and women start losing bone in their 40s. Women experience a rapid phase of loss during the first 5–10 years after menopause, due to loss of estrogen. In men, this phase is obscure, since there is only a slow and progressive decline in sex steroid production. Hence, the loss of bone in men is linear and slower.11 This loss of bone in both men and women lead to a more porous bone leading to a condition called osteoporosis.4

Various studies have demonstrated that osteoporotic individuals have altered morphology of mandible and also there exists a good correlation between the mandibular and skeletal bone mineral densities. Dental radiographs, especially panoramic images have been used to predict patients with low BMD. Hence, by using various qualitative and quantitative radiomorphometric indices, it is possible to measure the bone mineral density of mandible on panoramic radiographs. These radiographs are relatively inexpensive, and they are already being made regularly as an aid in the diagnosis of oral and dental diseases. They may also provide information on a patient’s osteoporotic status and thus display enormous potential in being used as a screening tool for osteoporosis.12 Therefore we as oral physicians can identify low BMD using the panoramic radiographs and create awareness of osteoporosis. Although many studies have been conducted on radiomorphometric indices of mandible, very few correlative studies have been conducted on younger populations. Therefore, in our study we also included younger individuals to determine whether osteoporotic bone changes occurred earlier than they were actually detected, by using mandibular indices. In addition, not many studies have conducted to study the effect of dentition on the indices. Hence, our study was conducted to go one step closer by also assessing the effect of dentition on the mandibular indices together with age and gender. In terms of age, GI (Table 2)showed a negative correlation with age which was statistically significant.AI also (Table 2) showed a downward trend with age which was of statistical significance. (p value <0.050) These findings are in accordance with a study conducted by Ledgerton et al.,6 Bras et al.13 and Kribss et al.14 This could be attributed to the age related bone loss.

A sharp decline in mean values of MI starting from the age of 61 years only in females was noted in our study (Table 4) which was of statistical significant. It is in accordance with a studies conducted by Knezovic Zlataric et al.15 and Govindraju et al.4 This could be due to post-menopausal bone loss. PMI had a significant influence on age. There was a drastic dip in the mean PMI values starting from the age of 41 years (Table 2) which was of statistical significance. These findings were in accordance with previous studies conducted by Raghdaa et al.16 Nemati, et al.17 and Bathla et al.18 It can be explained by the age changes in cortex.

Among the 3 categories of MCI, C1 was the most detected category followed by C2 and C3 being the least. This finding is consistent with the previous studies conducted by A Gulsahi et al.19 and Govindraju et al.4 C1 was seen in younger males and females, but as age advanced, the number of individuals who had C2 and C3 categories increased (Table 3) which was found to be statistically significant. This is correlating with the results of previous studies which were conducted by Knezovic-Zlataric et al.15 Gulsahi et al.19 and Haster et al.20 This is because the prevalence of porosity in the mandibular cortex increases with age. Several radiographic studies have shown reductions in mandibular cortical thickness in older females. Although both men and women are affected, women lose bone mass at a rate which is three times that of men, especially after menopause.

As discussed above, the mean GI values were considerably lower in females compared to males (Table 3) which was statistically significant. This finding is in accordance with a study conducted by Alonso MBCC et al.21 It can be explained by the constitutional differences between sexes. Our study reported a notable decrease in antegonial bone thickness (AI) among elderly females and that resorption was lower among elderly males (Table 3) which was of statistical significance. This is consistent with the studies conducted by Dutra et al.22 and Ivona Musa et al.23 The reason being that osteoporosis was more often seen in older females. The mean values of MI were lower in females compared to males (Table 3) which was statistically significant. This finding is in accordance with the previous studies conducted by Dagistan and Bilge24 and Alonso MBCC et al.21 The females of older age group demonstrated lower MI values (Table 4)which was of statistical significance. This is in accordance with the studies conducted by Benson et al., Dutra et al.25, Raghdaa et al. 16 and Ivona Musa et al.23 It could be attributed to the fact that osteoporosis was more often seen in older females.

There was no significant difference in the mean values of PMI between both sexes except in the age group of 31 to 40 years, where females had lower values (Table 4) which was found to be statistically insignificant. This finding is in accordance with a previous studies conducted by Raghdaa et al.16 This could be because of a lower distance between the mental foramen and the inferior cortex of the mandible owing to skeletal variations between sexes. However, this was in contrast to the study conducted by Hastar et al.20 It could be attributable to difference in race.

There was a statistically significant difference amongst the categories of MCI between males and females. C1 appearance was predominantly seen in males, C2 was equally seen among the either gender whereas C3 appearance was predominantly seen in females (Table 3). This finding is in agreement with the studies conducted by Knezovic-Zlataric et al.15 Gulsahi et al.19 Haster et al.20 and Govindraju et al.4 This might be explained by the hormonal differences between males and females resulting in more pronounced and faster bone mass loss in females. Some investigators have revealed the effect of dental status on radiomorphometric indices which was correlating in the present study as well. The mean GI values were lowest in completely edentulous patients followed by partially edentulous and then dentulous patients (Figure 2 Graph 2) which was statistically significant. These findings are in accordance with the studies conducted by Bras et al.13, Ledgerton et al.16 and Dutra et al.22 This could be attributed to the masticatory muscle atrophy with age in edentulous individuals. Similarly, the mean AI values were lowest among completely edentulous patients followed by partially edentulous and then dentulous patients (Figure 2) which was of statistical significance which is in concurrence to the previous studies conducted by Ledgerton et al.6 and Khayam et al.26 This could be due to the change in structure and function of masticatory muscles with age in edentulous individuals.

The mean MI values were highest among dentulous patients, followed by partially edentulous and then least in edentulous patients (Table 6), which was statistically significant. This is in concurrence with the previous study conducted by Ledgerton et al.6 This could be due to remodelling of edentulous mandible and masticatory muscles change in structure and function with age. However, it is in contrast with the study conducted by Dutra et al.22 which can be attributable to the difference in race, the age group selected and the span of edentulousness.

There was no significant difference in the mean values of PMI among different dental groups. (Figure 2). The findings of our study is in accordance with the studies conducted by Dutra et al.22, Ledgerton et al.6 and Raghdaa et al.16 The reason may be though there is alveolar bone resorption above the foramen, distance from foramen to inferior border remains constant throughout life. Amongst the three categories of MCI, we found C2 and C3 cortical appearances predominantly among partially and completely edentulous patients, whereas C1 in dentulous patients (Table 5) which was of statistical significance. Our study findings were in accordance with the findings of studies conducted by Gulsahi et al.19 and Nemati et al.17 This could be due to increase in the prevalence of porosity with the loss of teeth. Although radiomorphometric 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. Hence, it is advocated that oral physicians play an unique role in screening of patients for the evaluation of osteopenia /osteoporosis.

Source of Funding

None.

Conflict of Interest

None.