PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Dentinal Fluid”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1992

Fluid flow through cat dentine in vivo.

An outward flow of fluid through exposed dentine was demonstrated in anaesthetized cats. The flow was measured by observing the movement of the fat droplets of dilute milk in a glass capillary (i.d. 30 microns) with a microscope. The capillary was sealed to the dentine with a plastic cap. The resting flow rate through dentine exposed by fracturing off the tip of a cat's canine ranged from 2.8 to 50.9 pl.s-1.mm-2 (mean 18.1, SD 15.9, n = 12). Raising the pressure at the dentine surface to about 15 cmH2O stopped the flow. Immediately after cutting the pulp at the root apex, in 11 of 12 preparations, the flow reversed. The average flow rate was then 3.8 pl.s-1.mm-2 inward (range 8.4 outward to 15.9 inward, SD 5.4, n = 12). The inward flow after pulp section suggests that an osmotic effect may contribute to the net pressure causing flow. The average hydraulic conductance of the exposed dentine was 1.6 x 10(-8) m.s-1.kPa-1 (range 0.5-2.9, SD 0.8) before pulp section. After pulp section, it increased to an average of 2.5 x 10(-8) m.s-1.kPa-1 (range 0.8-5.2, SD 1.3).

Absorption↗
PubMedDate not supplied

Effect of bur cutting patterns and dentin bonding agents on dentin permeability in a fluid flow model.

This study investigated the effects of bur cutting surface roughness and bonding systems on dentin permeability. A conventional straight edged bur, cross-cut serrated bur and an extensively serrated bur were utilized with two different bonding systems. Null hypothesis was that increased surface roughness does not decrease the permeability of dentin sealing after application of bonding agents. This study incorporated a fluid flow model for measuring dentin permeability. Seventy caries-free extracted molars were used and sectioned 2 mm apical to the cementoenamel junction (CEJ). The pulp tissue was removed and the chamber cleaned using 37% phosphoric acid followed by 1:1 sodium hypochlorite solution. The specimens were mounted to plexiglass plates using cyanoacrylate cement. A flow system was established through the pulp chamber and gravity pressurized phosphate buffered saline (PBS) was forced into the chamber and the "closed system" permeability measured. Burs were used to prepare flat surfaces in dentin, and after etching with phosphoric acid, the "open tubule" permeability was determined. After applying the dentin bonding agents, fluid flow from the pulp chamber into dentin was again measured. The percentage of reduction in permeability following bonding agent application was then calculated. A two-way ANOVA found a significant (p<0.05) decrease in bonded dentin permeability in specimens prepared using the cross-cut serrated and extensively serrated bur as compared to the conventional straight-edged bur. No significant differences were detected between bonding systems and no combination of surface topography or bonding agent completely sealed the surface.

Analysis of Variance↗
PubMed2000

The effect of normal occlusal forces on fluid movement through human dentine in vitro.

Receptors inside human incisors appear to respond to stress (comparable to pressure as opposed to force) on the crown. This ability may be used to limit the stress applied to teeth or to discriminate between the hardness of objects clenched between upper and lower teeth. Here the hypothesis that these receptors are activated by fluid squeezed out of dentinal tubules when the loaded tooth is stressed was tested. Vertically compressing the crowns of extracted human teeth with loads of from 20 to 120 N, similar to those used in other studies and during natural chewing, did indeed displace fluid into the pulp. The fluid was displaced away from the crown immediately after the tooth had been loaded and moved back into the crown when the load was removed. The volume ranged from 3.5 to 22.2x10(3) pl, similar to that known to stimulate single pulpal nerve fibres. Thus, normal chewing forces could displace sufficient fluid out of dentine to excite putative mechanoreceptors somewhere inside the dentine/pulp complex.

Bite Force↗
PubMed1996

Fluid shifts across human dentine in vitro in response to hydrodynamic stimuli.

Most authorities agree that the hydrodynamic theory of dentine sensitivity best explains the stimulus-response relations of most painful stimuli. However, as the usual hydrodynamic stimuli are so different, it has been impossible to compare them. The equivalency of hydrodynamic stimuli can be evaluated from measurements of the fluid movement induced in vitro and relating this to the hydraulic conductance (Lp) of the same dentine specimen. From this determination, a common denominator is obtained which is equivalent to the hydrostatic pressure that would be required to cause the same magnitude of fluid movement. The purpose of this study was to measure the direction and magnitude of fluid shifts across dentine in extracted human crown segments with a flat, dentine occlusal surface in response to the following hydrodynamic stimuli; air blast, 56 degrees C water, 2 degrees C water, tactile and osmotic. In acid-etched superficial dentine, which simulates hypersensitive dentine, the largest to the smallest fluid flows obtained were: hot > cold > air blast > osmotic > tactile. When these were converted to equivalency units, the ranking of stimuli from strongest to weakest was hot > cold > air blast > osmotic > tactile. This new approach to comparing hydrodynamic stimuli should be verified in vivo.

Acid Etching, Dental↗
PubMed2002

The effect of tissue molecules on bacterial invasion of dentine.

Bacterial invasion of dentinal tubules is a critical step in the pathogenesis of dental caries and pulp and periapical disease. The purpose of this study was to determine the effect some molecules commonly found in saliva and dentinal tubule fluid may have on the bacterial invasion of dentine. The results showed that invasion of Streptococcus gordonii or Enterococcus faecalis cells was inhibited when the bacterial cells were in solution with mucin, immunoglobulin G (IgG) and serum, and this was related to bacterial cell aggregation, as a result of interaction with agglutinins, and/or inhibition of collagen binding. When dentine was soaked in growth media containing fibrinogen, IgG, albumin or serum prior to inoculation, bacterial invasion was inhibited. It is suggested that this may be due to reduced dentine permeability as a consequence of the deposition of the compounds within dentinal tubules.

Albumins↗
PubMed2000

Displacement of the contents of dentinal tubules and sensory transduction in intradental nerves of the cat.

Experiments were performed on anaesthetized cats to test the hypothesis that fluid flow through dentinal tubules is part of the mechanism involved in the transduction of pain-producing stimuli in teeth. In 11 animals, fluid flow through dentine and single- and multi-unit activity in intradental nerves were recorded simultaneously during the application of changes in hydrostatic pressure (-500 to +500 mm Hg) to exposed dentine. Seventeen A-fibres (conduction velocity (CV), 10.6-55.1 m s(-1)) were isolated that were pressure sensitive. The thresholds of these units in terms of dentinal fluid flow were in the range 0.3-2.1 nl s(-1) mm(-2) during outward flow from the pulp and 2.0-3.5 nl s(-1) mm(-2) during inward flow. All the units were more sensitive to outward than inward flow. Twenty-eight units (CV, 0.6-48.8 m s-1) were not pressure sensitive, and 12 of these had conduction velocities in the C-fibre range (< 2.5 m s(-1)). The velocities of the tubular contents were calculated by estimating the number and diameters of dentinal tubules exposed. At the threshold of single-fibre responses these velocities were in the range 31.7-222.9 microm s(-1) during outward flow 211.4-369.6 microm s-1 during inward flow. Repetitive pressure stimulation of dentine resulted in a progressive reduction in the evoked discharge, which was probably due to pulp damage. In seven animals, 10 single intradental nerve fibres were selected that responded to hydrostatic pressure stimuli and their responses to the application of hot, cold, osmotic, mechanical and drying stimuli to exposed dentine were investigated. With these stimuli dentinal fluid flow could not be recorded in vivo for technical reasons and was therefore recorded in vitro after completion of the electrophysiological recordings. With each form of stimulus, the discharge evoked in vivo was closely related to the flow predicted from the in vitro measurements. The results were therefore consistent with the hypothesis that the stimuli act through a common transduction mechanism that involves fluid flow through dentine.

Animals↗
PubMed2005

SEM-EDX study of prepared human dentine surfaces exposed to gingival retraction fluids.

OBJECTIVES: To evaluate the effects of gingival retraction fluids (GRF) on prepared dentine surfaces, and to test the null-hypothesis that prior exposure of dentine surfaces for prolonged period to any of the fluids evaluated does not influence acid-etching of the exposed surfaces. METHODS: The investigation was carried out using SEM and energy-dispersive X-ray analysis (EDX). The GRF studied were Hemodent (HMDT), Astringedent (AST) and Ultradent buffered 25% Aluminium Chloride (ULTB). Longitudinal sections of 220-grit ground dentine surfaces were exposed to GRF for 0.5-, 1-, 2- and 5-min (n=4 each). Another group of samples was produced by 20s application of 35% phosphoric acid (PA) on GRF-pretreated dentine. Control samples were not exposed to GRF. Differences in etching effect-a function of the Ca-contents detected by EDX, were analysed using Friedman's and Wilcoxon's rank test (P<0.05). RESULTS: The SEM demonstrated the presence of a relatively non-porous amorphous dentine matrix, but many of the dentine tubule orifices remained occluded. Granular precipitates, which remained even after acid-etching, were noted on surfaces exposed to Hemodent for 5 min. Characteristic crystal growth was observed on surfaces exposed to Astringedent for 1- or 2-min prior to acid-etching. The EDX data demonstrated that there were differences in resulting Ca-content; ULTB >AST>HMDT>ULTB+PA>HMDT+PA>AST+PA>PA, but AST and HMDT were not significantly different. CONCLUSIONS: The exposure of dentine prepared surfaces to these three GRF altered its morphology and reduced the dentine's susceptibility to acid-etching, thus the null-hypothesis is rejected.

Acid Etching, Dental↗
PubMed2004

Fluid movement across the resin-dentin interface during and after bonding.

This study evaluated the extent of water penetration through resin-dentin interfaces before and after being sealed with adhesives. Four adhesive resin systems (2 total-etch adhesives and 2 self-etching primer adhesives) were used in this study. Dentin disks were placed in a split-chamber device, and in situ fluid movement across dentin was measured, with and without physiological pressure, during bonding procedures or 24 hrs after bonding. The fluid movement across dentin occurs via dentin tubules after acid-etching. Large outward or inward fluid shifts across dentin were observed during air-drying and light-curing for resin application. The amount of fluid movement across resin-bonded dentin when total-etch adhesives were used was significantly greater than that with self-etching adhesives. The milder acid-etching effects of self-etching primers may retain hybridized smear plugs within the tubules that reduce outward fluid flow, resulting in superior dentin sealing.

Acid Etching, Dental↗