Hydrodynamic Theory (dentistry)
The Hydrodynamic or Fluid Movement theory is one of three main theories in dentistry developed to explain dentine hypersensitivity, which is a sharp, transient pain arising from stimuli exposure. It states that different types of stimuli act on exposed dentine, causing increased fluid flow through the dentinal tubules. In response to this movement, mechanoreceptors on the pulp nerves trigger the acute, temporary pain of dentine hypersensitivity. The fluid flow mechanism behind hydrodynamic theory was first introduced by Alfred Gysi in 1900, and subsequently developed by Martin Brännström in the 1960s through a series of experimental studies. Further supporting evidence has since been collected from epidemiological surveys and experimental data comparing dentinal tubule numbers in hypersensitive and non-hypersensitive teeth. Alternate theories include the “dentine innervation” and “odontoblast transduction” theories, both of which lack substantial supporting evidence. The ...
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Nervous System
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or '' efferent'' nerves, while those nerves that transmit information from the body to the CNS are called sensory nerves or '' afferent''. Spinal nerves are mixed nerves that serve both fu ...
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