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Oral implications of osteoporosis

aAssociate Professor, Department of Prosthodontics, University of Istanbul, Faculty

of Dentistry, Istanbul, Turkey

Received 7 January 2005;

revised 14 April 2005;

accepted 19 April 2005.

Istanbul, Turkey.

Available online 23 August 2005.

Objectives

The association between osteoporosis and oral health remains a matter of 

controversy. It is important to confirm whether there is a role of osteoporosis in bone

loss in the jaws, periodontal diseases, tooth loss, and other oral tissue changes. The

objective of this article is to review and summarize the published literature on the

associations between osteoporosis and various oral conditions such as bone loss in

the jaws, periodontal diseases, and tooth loss.

Methods

A search of the computerized database MEDLINE was conducted. Clinical

information concerning systemic osteoporosis and animal studies reporting possible

associations between osteoporosis and changes in the dental and oral tissues were

included. The review focus was on studies involving (1) methods for assessing bone

mineral density (BMD); (2) methods for assessing osteoporosis-related changes in

intraoral sites; (3) associations between mandibular BMD and skeletal BMD; (4)

changes in the jaws, periodontal tissues, and temporomandibular joint concurrent

with osteoporosis; (5) changes in the oral tissues following estrogen deficiency; and

(6) effects of estrogen-hormone replacement therapy and/or calcium and vitamin D

on oral health.

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Results

Ninety-seven studies conducted in various parts of the world were identified.

Evidence from prospective studies supports the contention that individuals with

osteoporosis may be at increased risk for the manifestations of oral osteoporosis;

however, such risk is not definitively proven. Studies suggest that findings on dental

panoramic radiographs may be used to detect individuals with low BMD.

Conclusions

Further well-controlled studies are needed to better elucidate the inter-relationship

between systemic and oral bone loss and to clarify whether dentists could usefully

provide early warning for osteoporosis risk.

Osteoporosis is defined as a skeletal disorder characterized by low bone mass and

microarchitectural deterioration of bone tissue leading to enhanced bone fragility,

with consequent increase in fracture risk.1 and 2 An osteoporotic fracture is an outcome

of trauma to bone of compromised strength, commonly first occurring in the vertebral

bodies and distal radius, both sites composed predominantly of medullary

(trabecular) bone.

The World Health Organization (WHO) has proposed bone mineral density (BMD)

measurements to establish the diagnosis of osteoporosis. T score is defined as the

number of standard deviations (SDs) above or below the mean BMD value for young

(25- to 45-year-old) adults of the same gender. This should be distinguished from a Z

score, which is defined as the number of SDs above or below the mean BMD for 

people of the same age and sex. The WHO defines osteoporosis as a T score at or 

below 2.5 (2.5 SDs below normal peak values for a young adult).2 and 3

The National Osteoporosis Foundation has identified many risk factors for 

osteoporosis and related to fractures in white postmenopausal women: personal

history of fractures in adulthood, history of fragility in a first degree relative, low body

weight, current smoking, and use of oral glucocorticoid therapy for more than 3

months. Additional risk factors are impaired vision, estrogen deficiency at an early

age (younger than 45 years), dementia, poor health, recent falls, low calcium intake,

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low physical activity, and alcohol intake more than 2 drinks per day. Systemic

conditions associated with increased risk for osteoporosis include chronic obstructive

pulmonary disease, gastrectomy, hyperparathyroidism, hypogonadism, multiple

myeloma, and celiac disease. Medications, in addition to oral glucocorticoids, that

are associated with reduced bone mass in adults include anticonvulsants,

gonadotropin-releasing hormone agonists, excessive thyroxine doses, and lithium.4

Effective preventive strategies must therefore be established, and should include

earlier diagnostic procedures and implementation of treatment. To effectively

evaluate the risk of osteoporosis and fracture, there is a need for more sensitive

tools to be developed, including not only BMD measurement, but also additional risk

assessment factors, such as age, weight, medication use, previous history of 

fractures, and maternal history of fractures.5

There is evidence that osteoporosis affects the craniofacial and oral structures,

although the contribution of osteoporosis in the loss of periodontal attachments,

teeth, and height of the residual ridge has not been clearly elucidated. Therefore, the

relationship between systemic osteoporosis and oral health is still a complex

problem of great interest to a large number of researchers and clinicians. In addition,

the dentist could screen patients with unrecognized osteoporosis using information

already availaible in the dental office. The goal of such screening is not to diagnose

osteoporosis but rather to identify individuals at risk for osteoporosis and refer them

appropriately.

The purpose of this article is to review and summarize the published literature

concerning possible associations between osteoporosis and various oral conditions

such as bone loss in the jaws, periodontal diseases, and tooth loss.

Measurement of bone density

A number of technologies can be used to assess bone density, including single

photon absorptiometry (SPA), dual photon absorptiometry (DPA), dual energy X-ray

absorptiometry (DXA), quantitative computed tomography (QCT), and radiographic

absorptiometry (RA). The radiation doses for all techniques except QCT are low.

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Quantative ultrasound uses sound waves rather than ionizing radiation to assess

properties of bone that are related to density and bone strength.

DXA is recognized as the best available technique for in vivo bone measurement.

DXA can measure BMD at the coxa or spine but can also be used to measure the

total amount of mineral in the whole skeleton or cubitus. Because BMD at the coxa is

the best predictor of coxa fracture, coxa BMD may be particularly useful in women

older than 65 years, since risk of coxa fracture rises rapidly after age 65.Spine BMD

is more sensitive to the effects of corticosteroids and may be the best choice for 

assessing and monitoring corticosteroid-treated patients.6

The value of QCT measurements for prediction of fractures, and therefore for makingclinical decisions, has not been studied well. RA can provide the basis

measurements such as the thickness of cortical bone and radiographic densitometry,

or the use of indices developed for research protocols. Characteristics and costs of 

this method are similar to those of peripheral densitometry. Ultrasound of the heel

resembles other peripheral measurements in terms of ability to predict fractures.

Radiographic assessment of intraoral sites

Various tecniques have been used for assessing osteoporotic changes at intraoral

sites, including SPA and DPA,7, 8 and 9 DXA,10, 11, 12 and 13 QCT,14, 15, 16 and 17 intraoral

radiographs,18, 19, 20, 21 and 22 and panoramic radiographs.22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 

36, 37 and 38 The majority of studies have used radiographs to assess anatomy and bone

density because the costs associated with DPA, DXA, and QCT techniques, as well

as access to the equipment, limit their usefulness for screening examinations by

dentists.

Recent studies have indicated that a panoramic radiograph may be one of tools that

can be employed to identify individuals with low BMD, high bone turnover, or high

risk of osteoporotic fracture.27, 30, 33, 34, 35, 36, 37 and 38 The validity of such a diagnostic tool

is dependent upon 2 factors. First, it is necessary that mandibular BMD relates

significantly to that of other sites in the affected skeleton, particularly in individuals

with osteoporosis. Second, the sensitivity and specificity of dental panoramic

radiographs in reflecting skeletal BMD must be high.34

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Radiographic bone density can be assessed from dental radiographs by 2 main

ways: by taking linear measurements (morphometric analysis) or by measuring

optical density of bone and comparing it with a reference step wedge (densitometric

analysis).31

A number of mandibular cortical indices have been developed to allow quantification

of mandibular bone mass and identification of osteoporosis.

Recently, tuned aperture computed tomography (TACT) has been shown to be an

accurate and alternative method to QCT for the evaluation of osseous changes in

the intraoral site in 3D.39, 40 and 41 Although many in vitro studies have been performed

with this system, there is a dearth of clinical reports.

Osteoporosis and its oral implications

Most studies with oral radiographic changes associated with osteoporosis have

focused on measures of jawbone mass or morphology. It has been shown that

mandibular BMD is correlated with skeletal bone density. Corten et al10 first

suggested the use of DXA for the mandible, although their study was limited to only

4 patients. Horner et al12 were the first to carry out mandibular DXA in a clinical

setting. They reported that the body of mandible may be the most appropriate site for 

any planned assessment of the validity of mandibular measurements as a predictor 

of general bone mass. In another study, Horner and Devlin13 showed that mandibular 

BMD measurements using DXA are significantly correlated with those of the lumbar 

vertebra, cubitus, and femoral neck. Klemetti et al14 and 42 reported significant

correlations between mandibular BMD using QCT and lumbar spine and femoral

neck BMD measured by DXA. Von Wowern8

used specially manufactured DPA

equipment for the mandible and cubitus.

Several studies have demonstrated that mandibular inferior cortical shape and width

on dental panoramic radiographs may be useful screening tools for low skeletal BMD

or increased risk of osteoporotic fracture.

Subjects with osteoporosis are more likely to show erosions of the inferior border of 

the mandible than controls.27, 30 and 33 Halling et al38 investigated the validity of the

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Klemetti index (KI) measured on panoramic radiographs. Bollen et al33 reported that

subjects with self-reported history of osteoporotic fracture tend to have increased

resorption and thinning of the mandibular lower cortex.

In another study by these authors, they demonstrated that the maxillary and

mandibular alveolar process radiographic fractal dimension is related to the alveolar 

process density, but is not related to the density of the spine, coxa, or radius.44White

and Rudolph47 found that patients with osteoporosis had an altered trabecular 

pattern in the jaws in comparison with normal subjects using dental radiographs.

In temporomandibular dysfunction (TMD), bony changes and bone resorption occur 

in both condyle and temporal components of temporomandibular joint and mayrange from mild decreases in cortical bone to severe destruction of condyle and

temporal components. Klemetti et al48 have reported that the habits and conditions

that provoke development of general bone loss in the skeleton may disturb the

functional harmony of the masticatory system and thus may increase the possibility

for temporomandibular disorders. Kirk50 stated that osteoporosis may be the most

significant risk factor for potential failure in initial surgical outcomes for painful and

dysfunctional temporomandibular joint derangement. He suggested that preoperative

diagnosis and evaluation of risk factors may necessitate selection of specific initial

surgical procedures that minimize the influence of concomitant risk factors for long-

term success.

A literature review published by Wactawski-Wende,51 found several similarities and

correlations between osteoporosis and periodontal disease. Like osteoporosis,

periodontitis is a silent disease, not causing symptoms until late in the disease

process when mobile teeth, abscesses, and tooth loss may occur. A history of 

previous bone loss, age, smoking, systemic disease, and certain medications (such

as chronic corticoteroid treatment) are common risk factors for both periodontitis and

osteoporosis. In addition, the pathophysiology of both diseases appear to have a

hereditary or, at least, familial component. Many,52, 53, 54 and 55 but not all,56 and 57 studies

have indicated an association of osteoporosis with the onset and progression of 

periodontal disease; however, a causal nature to this association is not firmly

established, since the results of studies may easily be confounded by factors such

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as oral hygiene, socioeconomic status, age, menopausal age, hormone intake,

smoking habits, and race.

Effects on oral health of medications for osteoporosis

The positive effects of estrogen-hormone replacement therapy and/or calcium and

vitamin D on the postcranial skeleton are well known, however, the effects of these

substances on oral bone is known less due to a lack of longitudinal studies being

performed. Several studies have found that HRT has a beneficial effect on tooth

loss,88, 89 and 90 mandibular bone density,91 and gingival bleeding.92 Bollen et al73 did not

prove any effect of hormone replacement therapy on the retention of teeth and

residual ridge resorption. With regard to the effects of calcium, it has been suggested

that low calcium intake may increase the risk of periodontal disease and oral bone

destruction.93 It has also been suggested that the combination of calcium plus

vitamin D may have beneficial effects on tooth retention.94 Civitelli et al95 have

previously reported that 3-year treatment with estrogen/hormone replacement

therapy (E/HRT) increases dental health and alveolar bone density in

postmenopausal women and calcium and vitamin D have a lesser effect. By

following these patients for an additional 2 years, these authors have found thatwomen taking E/HRT and/or calcium and vitamin D exhibited significant increases in

oral bone density.96

Conclusion

The available techniques for in vivo bone mass measurement techniques are

expensive and not cost-effective to screen the general population. Recent studies

have suggested that because dental panoramic radiographs are frequently made

during the general practice of dentistry, the findings on such radiographs may help

dentists to identify patients with undetected low BMD and refer them to medical

professionals for bone densitometry.

BMD in the mandible has proven in a number of studies to be positively correlated

with that in lumbar spine, femoral neck, and forearm, which are important sites in

osteoporosis. Osteoporosis has been found to be associated with periodontal bone

loss, tooth loss, and temporomandibular joint bone loss. Conflicting results highlight

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the controversy of whether a causal relationship between systemic bone loss and

various oral conditions is present or not. Further studies, especially in gender, race,

and age-specific groups, are needed to assess the role of osteoporosis in various

oral conditions such as oral bone loss, tooth loss, and periodontal diseases to

determine the clinical significance of osteoporosis therapies on oral health and to

elucidate whether dentists might be of value for initial screening for signs of 

osteoporosis.

References

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3 D.M. Eddy, C.C. Johnston, S.R. Cummings, B. Dawson-Hughes, R. Lindsay and

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