PubMed · 14695752
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Barry A Harrison, Timothy S J Shine, Martin L De Ruyter, Michael J Murray. 2004. Spinal cord temperature.. https://doi.org/10.1097/00000542-200401000-00046
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The thermal rise threshold of an 810-nm semi-conductor diode laser on the root surface when used in root canals in vitro for laser assisted root canal treatment is investigated in this study. A total of 50 human single-rooted extracted teeth were included. For this study, the canals were enlarged up to an apical size of ISO#50 file. Laser irradiation was performed with six different settings. Specimens were irradiated at 0.6-1 W output power at the distal end of the fiber and about 1-1.5 W output power in the continuous mode (CW) as two groups. In the third group, 0.6-1 W output power, 10 ms pulse length (PL) and 10 ms interval duration (ID) were selected. In three other groups 1-1.5 W output power were used with different PL and ID as following: PL 10 and ID 10 ms, PL 10 and ID 20 ms and PL 20 and ID 20 ms. The total irradiation time was from 5 to 20 s per canal with a 200 mum in diameter and 25 mm long tip. After laser treatment, the temperature changes at the outer root surface were registered by means of NiCr-Ni measuring sensors and a T 202 thermometer. The safe temperature threshold for applying this diode laser in root canal is considered as 7 degrees C increase. To avoid increasing the temperature changes at the outer root surface related to this threshold, following total irradiation times were found: 0.6-1 W output power (10 ms PL/10 ms ID): 20 s (s), 1-1.5 W output power (10 ms/10 ms and 20 ms/20 ms): 15 s, 0.6-1 W output power CW and 1-1.5 W output power (20 ms PL/10 ms ID): 10 s and 1-1.5 W output power CW: 5 s. In the first three groups, 5 s irradiation and 5 s rest period avoided a temperature increase above the threshold of 7 degrees C).
OBJECTIVE: To measure the surface and intra-pulpal temperature increases in vitro on upper and lower anterior teeth during tooth whitening procedures. METHOD: A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Intra-pulpal temperature readings were made on upper and lower central incisors, lateral incisors and canines. Four lamps recommended for tooth bleaching were tested; a plasma arc lamp, a xenon-halogen lamp, a standard halogen lamp and a diode laser lamp. Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. RESULTS: The increase in surface temperature readings ranged from 0.44 degrees C (luma arch) to 86.3 degrees C (laser) with no bleaching gel present. Intra-pulpal temperature increases ranged from 0.30 degrees C to 15.96 degrees C. The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. CONCLUSIONS: The increase in the intrapulpal temperature with most bleaching lamps was below the critical threshold of a 5.50 degrees C increase thought to produce irreversible pulpal damage. The only lamp that produced an intrapulpal temperature increase above this threshold was the laser-based lamp and caution is advised when using this equipment.
The cause of the increase in core temperature (CT) during hemodialysis (HD) is still under debate. It has been suggested that peripheral vasoconstriction as a result of hypovolemia, leading to a reduced dissipation of heat from the skin, is the main cause of this increase in CT. If so, then it would be expected that extracorporeal heat flow (Jex) needed to maintain a stable CT (isothermic; T-control = 0, no change in CT) is largely different between body temperature control HD combined with ultrafiltration (UF) and body temperature control HD without UF (isovolemic). Consequently, significant differences in DeltaCT would be expected between isovolemic HD and HD combined with UF at zero Jex (thermoneutral; E-control = 0, no supply or removal of thermal energy to and from the extracorporeal circulation). During the latter treatment, the CT is expected to increase. In this study, changes in thermal variables (CT and Jex), skin blood flow, energy expenditure, and cytokines (TNF-alpha, IL-1 receptor antagonist, and IL-6) were compared in 13 patients, each undergoing body temperature control (T-control = 0) HD without and with UF and energy-neutral (E-control = 0) HD without and with UF. CT increased equally during energy-neutral treatments, with (0.32 +/- 0.16 degrees C; P = 0.000) and without (0.27 +/- 0.29 degrees C; P = 0.006) UF. In body temperature control treatments, the relationship between Jex and UF tended to be significant (r = -0.51; P = 0.07); however, there was no significant difference in cooling requirements regardless of whether treatments were done without (-17.9 +/- 9.3W) or with UF (-17.8 +/- 13.27W). Changes in energy expenditure did not differ among the four treatment modes. There were no significant differences in pre- and postdialysis levels of cytokines within or between treatments. Although fluid removal has an effect on thermal variables, no single mechanism seems to be responsible for the increased heat accumulation during HD.