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Thermal stimulation of dentinal tubules
Published in J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares, Biodental Engineering V, 2019
Paulo A.G. Piloto, Joana F. Piloto
The thermal properties were measured by Brow et al. (1970), considering the specific heat equal to 1590 J/kgK, the conductivity equal to 0.48 W/mK and the specific mass equal to 1960 kg/m3. The thermal analysis of dentine region depends mainly on the thermal properties of the materials involved, which present also a large variability, according to data reported in Lin et al. (2011, 2010). The geometry of dentinal tubules also affects the temperature field in this region. A fluid structure interaction is expected in the dentine region. This fluid structure interaction is modelled herein by a convective bidirectional heat transfer between the fluid region (dentinal fluid) and the solid region (dentine). According to the hydrodynamic theory, thermal stimulation causes dentinal fluid motion. The sense of the motion depends on the type of stimuli. Hot stimulus causes inward fluid motion toward the pulp, while cold stimulus causes outward motion of the fluid. This model only includes the behaviour of the solid region but takes into account the thermal effect of the fluid. The simulation time depends on the duration of the stimuli. The typical time increment used in numerical simulation is 1 s, with the possibility to be reduced to 0.1 s.
Tooth Sensitivity Associated with Tooth Whitening
Published in Linda Greenwall, Tooth Whitening Techniques, 2017
Fluoride reduces sensitivity by blocking the tubules. This restricts the ingress of fluids according to the hydrodynamic theory of pain (Bartlett and Ide 1999). A neutral fluoride has been recommended for treatment use, such as PreviDent 5000 Plus (Colgate Oral Pharmaceuticals).
Key terms
Published in Vivian A. Elwell, Ramez Kirollos, Syed Al-Haddad, Neurosurgery, 2014
Vivian A. Elwell, Ramez Kirollos, Syed Al-Haddad
Syringomyelia – the development of a fluid-filled cavity or syrinx within the spinal cord. Several theories have been put forth to explain the pathogenesis of syringomyelia. Gardner’s hydrodynamic theory – results from a ‘water hammer’-like transmission of pulsatile CSF pressure via a communication between the fourth ventricle and the central canal of the spinal cord through the obex. There are craniospinal pressure differentials in the setting of fourth ventricular outlet obstruction; these differentials favour cerebrospinal fluid shifts from the fourth ventricle of the brain through the central canal of the spinal cord.William’s theory (craniospinal pressure dissociation) – due to a differential between intracranial pressure and spinal pressure caused by a valve-like action at the foramen magnum by the tonsils. An increase in subarachnoid fluid pressure from increased venous pressure during coughing or a valsalva manoeuvre is localized to the intracranial compartment.Oldfield’s theory – demonstrates that downward movement of the cerebellar tonsils during systole can be visualized with dynamic magnetic resonance imaging (MRI). This oscillation creates a piston effect in the spinal subarachnoid space that acts on the surface of the spinal cord and forces CSF through the perivascular and interstitial spaces into the syrinx, increasing intramedullary pressure. Signs and symptoms of neurological dysfunction that appear with distension of the syrinx are due to compression of long tracts, neurons and microcirculation. Symptoms referable to increased intramedullary pressure are potentially reversible by syrinx decompression.
Odontoblasts are cold sensory cells in teeth
Published in Temperature, 2023
Pamela Sotelo-Hitschfeld, Laura Bernal, Katharina Zimmermann
In teeth, there was so far little progress in the molecular detection mechanism of cold temperature and cold pain. So far, the tooth pulp’s sensory plexus of Raschkow was widely accepted as the source of nociception from temperature extremes. However, in teeth, the sensory axons are embedded in the two layers of hard substances, enamel and dentin, which provide ceramics-like thermal insulation. Thus, any damaging thermal stimulus is transmitted and potentially transformed through this anatomical hierarchy (Figure 1) before it will activate molecules like ion channels on the nociceptive afferent nerves in the tooth pulp. Therefore, in the most widely accepted theory of thermally induced tooth pain, mechanosensors detect thermally induced shear forces in the dentinal tubules because, when tooth temperature changes, the dentinal fluid moves; a hypothesis which is termed Brännström’s hydrodynamic theory as it was introduced by the Swedish dentist Martin Brännström in the 1960s.
Prevalence of self-reported versus diagnosed dentinal hypersensitivity: a cross-sectional study and ROC curve analysis
Published in Acta Odontologica Scandinavica, 2019
Nayara Franciele Figueiredo Barroso, Polyana Matos Alcântara, Adriana Maria Botelho, Dhelfeson Willya Douglas-de-Oliveira, Patrícia Furtado Gonçalves, Olga Dumont Flecha
Several theories attempt to explain the mechanism of dentin hypersensitivity. The most accepted is the hydrodynamic theory, that postulates that the fluids of exposed tubules are disturbed by temperature, physical or osmotic changes and these changes and movements in dentin fluid flow stimulate baroreceptors present in the pulp and dentin, leading to neural discharge and resulting in pain [4].