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Results for “Dentin Permeability”

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PubMed2005

Pressure transmission across dentine in response to an external pressure: a laboratory study.

PURPOSE: To determine whether transducers could provide a convenient method of measuring dentine permeability and to investigate the effects of removal of pulp tissue and perfusion time on the pressure increase across human dentine after low-pressure perfusion. METHOD: Human premolar teeth that had been stored for 1-2 months were prepared for full crown preparations. The pulp tissue was removed from half the samples and all the coronal segments perfused with saline at 1.3kPa for varying times. An external pressure was then applied and the response within the pulp chambers recorded with transducers. RESULTS: Extirpation of pulp tissue reduced the rate of rise of pressure inside the pulp chamber by approximately 50%. Perfusion at 1.3kPa for up to 1h had no effect on pressure rise, but 6h of perfusion produced a very significant increase. CONCLUSION: Transducers can provide a relatively simple, convenient and clinically relevant measurement of dentine permeability. For stored coronal segments that have been perfused at physiological pressures, extirpation of pulp tissue and perfusion time have significant effects on pressure transmission across dentine.

Adolescent↗
PubMed2005

[The sealing effects of three desensitizers on tubule:an SEM investigation].

PURPOSE: The purpose of this in vitro study was to evaluate the sealing effects on tubule by three different dentin desensitizers. METHODS: 48 freshly extracted human premolars were selected. Their buccal dentin was exposed and a standardized circular area was isolated. They were randomly divided into three experiment groups and one control group. Dentin desensitizers included Systemp desensitizer, Seal&protect desensitizer and Gluma desensitizer. Twelve teeth were prepared for each test group (36 teeth total), and the other twelve teeth were selected as a control group. After the removal of cement, the dentin surfaces were cleaned, treated. Then the teeth were vertically cleaved into two sections. The surface and section of these teeth were observed by means of a scanning electron microscope. RESULTS: All 3 desensitizers could seal the tubules on dentin surface. Systemp desensitizer's dentin permeability was better than Seal&protect, but Gluma had no dentin permeability. CONCLUSION: 3 desensitizers had sealing effect on tubule, systemo desensitizer was the best one.

Bicuspid↗
PubMedDate not supplied

The clinical significance and management of microleakage. Part one.

This research reviews relevant articles related to microleakage from 1966 to the present. The review discusses what the sensation of microleakage is clinically; how dentin permeability is related to microleakage; how the quality of dentin affects permeability and microleakage; what the effects of bacterial infiltration from microleakage can be, as well as the body's defenses against bacterial infiltration within the tooth complex; how caries and microleakage are related; and how various materials and procedures can be used to limit microleakage.

Bacteria, Anaerobic↗
PubMed2003

Chelating agents in root canal treatment: mode of action and indications for their use.

Chelating agents were introduced into endodontics as an aid for the preparation of narrow and calcified root canals in 1957 by Nygaard-Østby. A liquid solution of ethylenediaminetetraacetic acid (EDTA) was thought to chemically soften the root canal dentine and dissolve the smear layer, as well as to increase dentine permeability. Although the efficacy of EDTA preparations in softening root dentine has been debated, chelator preparations have regained popularity recently. Almost all manufacturers of nickel-titanium instruments recommend their use as a lubricant during rotary root canal preparation. Additionally, a final irrigation of the root canal with 15-17% EDTA solutions to dissolve the smear layer is recommended in many textbooks. This paper reviews the relevant literature on chelating agents, presents an overview of the chemical and pharmacological properties of EDTA preparations and makes recommendations for their clinical use.

Anti-Infective Agents↗
PubMed1998

Eugenol diffusion through dentin related to dentin hydraulic conductance.

OBJECTIVES: The purpose of this study was (1) to find an easy way of evaluating the concentration of eugenol in cell culture fluids; (2) to confirm the relationship between the concentration and the cytotoxicity of eugenol in vitro; (3) to evaluate the cytotoxicity of four temporary eugenol-based filling materials: IRM, super EBA, Kalsogen and zinc oxide-eugenol cement; and (4) to establish a relationship between dentin permeability, eugenol diffusion and cytotoxicity. METHODS: (1) The concentration of eugenol was measured with a spectrofluorimeter; (2) the cell viability of L 929 cells cultivated for 24 h with eugenol-containing medium was evaluated by the MTT assay; (3) after measurement of hydraulic conductance, occlusal cavities in human teeth in vitro were filled with the restorative materials. The cytotoxicity was measured with undiluted test medium and with various dilutions in culture medium; (4) after Lp measurement, the eugenol concentration in the media in the pulp chamber that diffused from IRM and 10(3) mol/l eugenol solution was measured. RESULTS: (1) A proportional relationship (p = 0.001 and r = 1) was found between the concentration of eugenol; (2) eugenol started to be cytotoxic at 10(-5) mol/l and killed 95% of the cells at 10(-3) mol/l; (3) zinc oxide-eugenol cement was the most cytotoxic filling material when tested with the 1:100 dilution; (4) a significant relationship was found between Lp and cytotoxicity (p = 0.04) depending on the dilution of the test medium. A significant relationship was found between Lp and eugenol diffusion from a 10(-3) mol/l solution (p = 0.03) but not between Lp and eugenol diffusing from solid IRM (non significant). SIGNIFICANCE: Eugenol diffusion from zinc oxide-eugenol cement appears to depend more on the role of hydrolysis of eugenol from zinc oxide-eugenol cement than on dentin permeability.

Analysis of Variance↗
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↗
PubMed1991

The permeability of cat dentine in vivo and in vitro.

The apparent impermeability of dentinal tubules to chemicals applied to exposed dentine in vivo was investigated. It was shown that whereas Evans' blue diffused readily into dentine in extracted teeth, it did not do so in visible amounts when it was applied in vivo. In the in vitro experiments, decreasing the pressure of the Evans' blue solution to 20 cmH2O below atmospheric apparently prevented the dye entering the tubules, while increasing the pressure of the solution to 15 cmH2O or more above atmospheric in vivo resulted in the dye penetrating the dentine in high concentrations. It is concluded that, in cat dentine in vivo, there is an outward flow of fluid through exposed dentinal tubules, and that this flow is sufficient to substantially reduce diffusion into the tubules of chemicals such as Evans' blue.

Animals↗
PubMed2000

Permeability of demineralized dentin to HEMA.

OBJECTIVES: The objectives of this study were to develop a macromodel of the demineralized layer of dentin that is formed after acid-etching, and to determine if the amount of HEMA uptake was responsive to air drying. The hypothesis that was tested was that HEMA uptake by demineralized dentin depends upon the degree of expansion of the collagen fibril network. METHODS: Dentin cubes (2 x 2 x 2 mm) were prepared in coronal dentin from extracted unerupted human third molars. They were incubated in 100% HEMA for up to 1000 min and then removed and blotted free of excess adherent HEMA. The HEMA taken up by each cube was extracted in 2 ml of water for 1 hr with shaking. This was repeated and the extracts combined. HEMA was quantitated spectrophometrically. The dentin cubes were then demineralized in 0.5 M EDTA for 10 days and the HEMA uptake remeasured at 1, 10, 100 and 1000 min. Then the cubes were air-dried and the HEMA uptake remeasured. After re-expanding the specimens in water, the cubes were stiffened in ascending concentrations of acetone of 100%, then allowed to air dry again in a more expanded state, and HEMA uptake was remeasured. Finally, after rehydration, the dentin cubes were "acid-etched" for 1 or 10 min with 37 wt% phosphoric acid and HEMA uptake remeasured. RESULTS: Before demineralization, the dentin took up little HEMA (ca. 4.8 x 10(-7) moles min-3) compared to after demineralization when the uptake for 10, 100 and 1000 min was 27.4, 43.8 and 51.4 x 10(-3) moles mm-3, respectively. Acid etching for 1 or 10 min had no effect on HEMA uptake. Air drying produced a 72% volumetric shrinkage but a 97% reduction in uptake. When the demineralized matrix was stiffened in acetone prior to air-drying, the volumetric shrinkage was only 27% and the HEMA uptake only fell 16% compared to the wet, fully expanded condition. SIGNIFICANCE: The results support the hypothesis that the uptake of HEMA by demineralized dentin depends on the degree of expansion of the dentin matrix.

Acid Etching, Dental↗
PubMedDate not supplied

Permeability of root dentin to epinephrine released from gingival retraction cord.

The permeation of racemic epinephrine across roots of human molar crown segments was studied in vitro. Permeation was measured in the presence of cementum, with cementum removed (dentin exposed), and with and without dentin smear layers. Epinephrine was initially detected at 10 minutes and reached a steady state in 70 minutes. Epinephrine flux (the product of concentration and the flow rate per unit of dentin surface area) significantly increased when both the cementum and dentin smear layers were removed. The T1/2 (half-time in minutes necessary to reach steady-state diffusion) was zero with intact cementum and increased to approximately 40 minutes in dentin with and without smear layers. This study suggests that the permeation of epinephrine across root surfaces is prevented by the presence of cementum and retarded by the presence of dentin smear layers. Also, the data suggest that root dentin is another source of absorption when epinephrine-impregnated retraction cord is applied to the gingival sulcus.

Absorption↗
PubMed2004

Assessment of morphological changes and permeability of apical dentin surfaces induced by Nd:Yag laser irradiation through retrograde cavity surfaces.

The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces induced by Nd:YAG laser irradiation at different power settings with and without a laser initiator. Seventy five single rooted human maxillary anterior teeth were used. Following the establishment of the working lengths, the root canals were enlarged with step-back technique. The apex of each root was resected 3 mm perpendicular to its long axis. Standard Class I cavities of 2 mm depth and 2 mm width were prepared. The teeth were randomly divided into five groups with fifteen teeth in each. In Group 1, the retrograde cavity preparations were lased with Nd:YAG laser at 2 W and those in Group 2 preparations were lased with Nd:YAG laser at 3.2 W. In Group 3, the retrograde cavity surfaces were lased with Nd:YAG laser at 2 W following the application of India ink. Group 4 was lased with the same settings of Group 2 after an absorbent cotton point soaked with India ink was inserted into the cut dentinal surfaces and the inner walls of the apical preparations. Group 5 served as control. Five teeth from each group were examined using scanning electron microscopy (SEM). The amounts of smear layer, debris, and recrystalized dentin present were assessed and scored. Retrograde cavities of ten teeth from each group were filled with amalgam to examine apical dye penetration. The teeth were immersed in 2% basic fuscin and kept for 48 hours. Dye penetration was evaluated by stereomicroscope at a magnification of X10. The results showed the usage of India ink with Nd:YAG laser enhanced the amount of melting and recrystalization of dentin and the radiation and initiator increased the leakage.

Analysis of Variance↗
PubMedDate not supplied

The clinical significance and management of microleakage. Part two.

This research reviews relevant articles related to microleakage from 1966 to the present. The review discusses what the sensation of microleakage is clinically; how dentin permeability is related to microleakage; how the quality of dentin affects permeability and microleakage; what the effects of bacterial infiltration from microleakage can be, as well as the body's defenses against bacterial infiltration within the tooth complex; how caries and microleakage are related; and how various materials and procedures can be used to limit microleakage. Part Two reviews the use of materials, technique, and procedures to limit microleakage, and specifically how the use of various dentin and enamel bonding materials can be used to limit microleakage.

Composite Resins↗
PubMed2002

Pulp-dentin biology in restorative dentistry. Part 6: Reactions to restorative materials, tooth-restoration interfaces, and adhesive techniques.

A number of defense mechanisms may be activated in conjunction with restorative dental treatment. Tissue changes that lead to reduced dentinal permeability are important to minimize pulpal reactions. The healing potentials of the pulp-dentin complex are significant, and restorative dentistry is dependent on the available defense reactions. Clinicians should intentionally include considerations of these reactions in their treatment planning and during restorative treatment.

Adult↗
PubMed1999

Scanning electron microscopy (SEM) investigation of selected desensitizing agents in the dentine disc model.

Dentine sensitivity is a painful clinical conditions that can affect up to 35% of the population at any one time. Both professionally available (in-office) or commercially available (over-the-counter) products have been used to treat dentine sensitivity. The aim of the present study was to investigate whether selected in-office desensitizing agents occluded dentine tubules in the dentine disc model. Both surface effects and tubule penetration of the five selected test products were examined by scanning electron microscopy. The results of the present study appeared to demonstrate that all of the applied desensitizing agents produced some occlusion of the tubules although the level of coverage and occlusion varied between the products. Of all the agents tested, ferric oxalate, the active ingredient of Sensodyne Sealant, produced crystal-like structures which occluded a higher proportion of the tubules across the dentine disc surface. ALL-BOND 2 and One-Step (both light-cured primer systems) produced similar crystal-like structures and, although coverage was not uniform across the disc surface, there was some reduction in tubule diameter. These three products, however, appeared to be more effective than either Butler Protect (potassium oxalate) or Oxa-gel (potassium oxalate in a gel) where there was a marked decrease in both the level of coverage and tubule occlusion. Both quantitative and functional studies are required in order to determine the effects of these agents on dentine permeability (fluid flow) as well as clinical studies to determine their effectiveness over time in reducing pain arising from dentine sensitivity.

Dentifrices↗