Mechanisms leading to musculoskeletal disorders in dentistry.

BACKGROUND The authors reviewed the implications of prolonged, seated working postures on dental operator health and the potential development of musculoskeletal disorders, or MSDs. TYPES OF STUDIES REVIEWED The authors reviewed studies to assess the mechanisms associated with the development of musculoskeletal pain and MSDs among dental operators. Some studies investigated work duration, operator positioning and the physiological effects of various static sitting postures. Others explored the relationships between prolonged muscle contraction and muscle imbalances, as related to the development of pain and MSDs. RESULTS This review advances the idea that the causes of musculoskeletal pain and disorders common to dental operators are multifactorial. Physiological changes that accompany these disorders can be related to practices used by today's operators-primarily being seated for prolonged periods. Studies associated such postures with increased disk pressures and spinal hypomobility, which are factors that may lead to degenerative changes within the lumbar spine and low back pain or injury. There is a relationship shown between prolonged, static (motionless) muscle contractions and muscle ischemia or necrosis. Weak postural muscles of the trunk and shoulder may lead to poor operator posture. As muscles adapt by lengthening or shortening to accommodate these postures, a muscle imbalance may result, leading to structural damage and pain. CLINICAL IMPLICATIONS A significant number of today's dental operators experience musculoskeletal pain and are at risk of developing serious MSDs. A thorough understanding of the underlying physiological mechanisms leading to these problems is necessary to develop and implement a comprehensive approach to minimize the risks of a work-related injury.