Nutrition and Oral Medicine (Nutrition and Health)

Chapter 15 / Osteoporosis 26115 OsteoporosisElizabeth A. Krall1. INTRODUCTIONTooth loss and periodontal diseases become more prevalent with advancing age andresult from the interaction of many factors, including local oral conditions, poor hygienepractices, lack of access to dental care, genetics, and systemic diseases. Osteoporosis ischaracterized by a decline in bone density and quality that predisposes to fracture and isone of several systemic diseases that has been hypothesized to increase the risks ofperiodontal disease and tooth loss (1). Although the number of studies of these associationscontinues to grow as precise methods to measure both oral and systemic bonemineral density are developed, a physiological mechanism for the associations betweenosteoporosis and these oral conditions has yet to be clearly identified. The majority ofhuman studies to date have not been able to distinguish between causation and mereassociation.2. BONE LOSS IN ADULTSSkeletal tissue exists in a dynamic state. Bone mineral at discrete sites throughout theskeleton is continuously being broken down (resorbed) by the osteoclasts and reformedby osteoblasts in a series of coordinated, or coupled, actions. The resorptive phase of thisremodeling process is estimated to last 10 d, while replacement of lost bone continues forapprox 3–4 mo (2). In young, healthy adults, the two phases are balanced so that theamount of bone mineral remains fairly constant. In middle-aged and older adults and indisease states such as osteoporosis, the phases tend to be uncoupled and dominated byresorption. The result is a net loss of bone mineral over time.The decline in bone mineral content and the structural deterioration in osteoporosis areevident microscopically. The compact cortical layer that forms the exterior shell becomesthin, and the normally dense network of calcified trabeculae in the bone interior alsobecomes thin and disconnected. On appearance, the bone is abnormally porous, whichgives the disease its name. These changes result in bone that is fragile and susceptible tofracture even with a low amount of trauma.This loss of mineral can be measured by dual or single x-ray absorptiometry to determinea person’s bone mineral density (BMD) at specific skeletal sites. BMD is comparedFrom: Nutrition and Oral MedicineEdited by: R. Touger-Decker, D. A. Sirois, and C. C. Mobley © Humana Press Inc., Totowa, NJ261