Tae-Ju Oh, DDS, MS† Jill Bashutski, DDS‡ William V. Giannobile, DDS, DMedSc§ Abstract Osteoporosis is a systemic skeletal disease manifested by reduced bone strength, decreased bone mineral density, and alteration of bony architecture. It can develop when bone resorption significantly overrides bone formation, either through imbalance in the genesis and apoptosis of osteoblasts and osteoclasts or through inappropriate regulation of bone remodeling. Oral bone loss (e.g., periodontitis, tooth loss, and implant bone loss) is caused by breakdown of bone homeostasis in the oral cavity. Both osteoporosis and periodontitis are bone-resorptive, host-dependent, multifactorial diseases, and bone loss is stimulated, systemically or locally, by cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor-alpha. Although some contradictory results exist, a large body of literature supports an association between systemic and oral bone loss. Individuals with systemic or oral bone loss should be closely managed with a clinical protocol that minimizes further deterioration of systemic or oral bony structures. Additional studies are needed to clarify the causality and/or association between systemic and oral bone loss and to determine the most efficacious therapeutic approach for the prevention and treatment of systemic/oral bone loss. Citation: Oh T, Bashutski J, Giannobile W. The interrelationship between osteoporosis and oral bone loss. Grand Rounds Oral- Sys Med. 2007;2:10-21. (Digital version Grand Rounds Oral-Sys Med. 2007;2:10-21c.) (A complimentary copy of this article may be downloaded at www.thesystemiclink.com.) Key Words: Bone loss, osteopenia, osteoporosis, periodontitis, treatment Introduction O steoporosis is a systemic skeletal disease manifested by reduced bone strength, decreased bone mineral density (BMD), and altered macrogeometry and microscopic architecture, and resultant increased risk of fractures. A recent report revealed that osteoporosis affects more than 10 million individuals aged 50 years or more; an ad- ditional 33.6 million are affected by osteopenia (low bone mass) and consequently are at risk for osteoporosis and its complications. 1 Because of the positive relationship between age and bone loss, the prevalence of osteoporosis increases from 19% among women 65- to 74- years old to more than 50% in women aged 85 years or more. 1 As the elderly popu- lation continues to grow, the number of people aged 50 or more with osteoporosis is expected to increase to 12 million by 2010 and to nearly 14 million by 2020. 1 In the United States (U.S.) approximately 1.5 million fractures each year are attributable to osteoporosis, as are ap- proximately 500,000 hospitalizations, 800,000 emergency department visits, 2.6 million physician visits, and 180,000 nursing home placements. 1 Worldwide, the morbidity, mortality, and healthcare costs related to osteoporosis and result- ing in low-trauma fractures are significant. 1 Osteoporosis is defined by the World Health Organization (WHO) as a bone mineral density (BMD) that is 2.5 standard deviations (SDs) below the young normal. 2 Osteopenia is de- fined as a BMD between 1 and 2.5 SDs (Table 1). 2 According to the WHO assessment, the patient is assigned a score that rep- resents a comparison to the average young (25- to 45-year- old) healthy adult of the same gender (a T-score) or to the average healthy age- and sex-matched patient (a Z-score). A 10 GRAND ROUNDS IN ORAL -SYSTEMIC MEDICINE • MAY 2007 • VOL . 2, NO. 2 Literature Review THE INTERRELATIONSHIP BETWEEN OSTEOPOROSIS AND ORAL BONE LOSS † Clinical Assistant Professor, Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI ‡ Graduate Student, Graduate Periodontics, Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI § Najjar Professor of Dentistry and Biomedical Engineering, Department of Periodontics and Oral Medicine, School of Dentistry, and Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, MI