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Objectives: The purpose of this study was to evaluate the changes in dentinal permeability (i.e. hydraulic conductance) after prophylactic treatment performed using prophy-powders with air-polishing system or prophy-pastes applied on exposed middle dentine. The changes in dentine morphology were evaluate by SEM., Study Design: Several prophylactic pastes or air-polishing powders were tested in this study. Dentine discs from human third molars were used to study the quantitative reduction of the dentine permeability under simulated pulpal pressure (20 cm H₂O). Further specimens were gold-coated and observed with the use of a SEM., Results: The results of this study showed different reductions of dentin permeability effects based on the type of product employed (i.e. prophylactic paste or air-polishing powders). The use of Sylc bioactive glass and sodium bicarbonate were the most effective in reducing dentine permeability of the specimens etched with the phosphoric. The air-polishing procedures performed with Sylc bioactive glass created a dentine surface devoid of exposed dentinal tubules due to the presence of a compact multilayered smear layer. Colgate Sensitive Pro-Relief and Nupro NU-Solution reduced the dentine permeability up to 69.8% and 66.9% respectively., Conclusion: Although all the tested products are able to statistically reduce dentine permeability, Sylc bioactive glass is an innovative and effective product suitable for the reducing of the dentine permeability during prophylactic procedures of air-polishing.

The development of cytotoxic changes in the dental pulp is due, in large part, to the permeability of dentine. That is, if dentine were impermeable, these changes would not occur. Dentine permeability is not uniform; it tends to be low over the incisal edges but high over the pulp horns of posterior teeth. It is relatively low beneath the amelo-dentinal junction or the cemento-dentinal junction but increases dramatically near the pulp chamber. Buccal dentine is less permeable than occlusal dentine, while radicular dentine permeability is much lower than that of coronal dentine. The presence or absence of a smear layer has a profound influence on dentine permeability. Tubular sclerosis or dental caries produces large reductions in dentine permeability. Dentine is an important barrier to the diffusion of substances toward the pulp. It both restricts diffusional surface area and dissipates the concentrations of substances driving diffusion across dentine. Further, there is evidence that dentine can interact in many different ways with a variety of solutes as they diffuse across dentine. New in vitro model systems can be modified to simulate more closely conditions in vivo where dentine is interposed between various dental materials and the pulp. Thus, the development of in vitro methods of biocompatibility testing that include dentine should improve the correlation between laboratory and clinical results. [ABSTRACT FROM AUTHOR]

The purpose of this in vitro study was to evaluate the efficacy of a new resin emulsion (Pain-Free® Desensitizer) treatment for dentine hypersensitivity, for its ability to decrease dentine permeability. Crown segments were prepared from extracted, unerupted human 3rd molars by horizontal sectioning to remove occlusal enamel and the roots. The specimens were allocated in one of two groups: In group 1, the dentine surface was acid-etched to simulate the patent tubules of hypersensitive dentine. In group 2, the mineralized dentine surface was polished free of smear layer using a hydroxyapatite paste and ultrasonication. The hydraulic conductance of each specimen was then measured to obtain a pretreatment of control value. After a single treatment with resin desensitizer, the permeability was remeasured at 5 min, 1 day, 1 week and 1 month. Between measurements, the specimens were stored in buffer solution to simulate the solubilizing effects of saliva. Parallel specimens were followed by SEM examination. The results showed that a single treatment with resin desensitizer produced large, immediate, reductions in dentine permeability in both acid-etched and mineralized surfaces. In the acid-etched (group 1) specimens, the permeability returned to control values within 7 days, while the permeability of the group 2 specimens remained low even after 30 days of soaking. This simple treatment for occluding dentinal tubules may provide sufficient temporary reduction in dentine permeability to permit the development of natural desensitization. [ABSTRACT FROM AUTHOR]

The use of contemporary endodontic methods of treatment do not always result in elimination of chronic nodus in periodontum, and filled teeth often remain potential noduses of infection, notwithstanding the impression of clinical and roentgenological wellness. Study of permeability of tooth root dentine under effect of medicines and microorganisms was done by means of introduction of colorant into the canal by iodine-electrophoresis method, observation of permeability of medicine from the canal through hard tissues of tooth and inhibition of growth of microorganisms in nutrient medium. It has been found out that the maximum permeability of tooth root dentine was observed in the cervical third of the root.

Dentine adhesives are often placed directly on dentine from which the smear layer has been removed, the thickness of the dentine is minimal and the potential for diffusion of adhesive components into the pulp is greatest. The permeability of the dentine is one factor that should be critical to whether sufficient diffusion of adhesive components occurs to cause damage to pulpal cells. Dentine discs were prepared and divided into those with low‐, medium‐, and high‐permeability. They were then treated with four different dentine adhesives, after which the pulpal side of the dentine was placed in contact with 1 mL of cell‐culture medium. The medium was collected at 24 h intervals for 168 h, and was then placed on monolayers of human pulpal fibroblasts for 24 h. The response of the cells was assessed by succinic dehydrogenase activity (MTT method). The results showed that four dentine adhesive systems released sufficient components to cause suppression of cellular metabolism through dentine. High‐permeability dentine generally allowed more diffusion of these components, but the effect of dentine permeability depended on the material. On the other hand, the time interval between the application of the bonding agent and collection of the eluant was consistently important for all materials. Materials were most cytotoxic at early intervals, and were generally less cytotoxic at later intervals, although there were exceptions and there was persistent (> 15%) suppression of cellular metabolism even at late (168 h) intervals. The results suggest that application of these materials to dentine, and particularly dentine with high permeability, poses a potential risk to the health of pulpal tissues. [ABSTRACT FROM AUTHOR]

Objectives: The objectives of this paper are to review the structure of dentine as it pertains to adhesive bonding and to describe the importance of resin permeation into dentinal tubules and into spaces created between collagen fibrils by acid-etching during resin bonding. The advantages and disadvantages of separate acid-etching, priming and adhesive applications are discussed., Data Sources: Although not an exhaustive review, the concepts included in the review were obtained from the dentine bonding literature., Study Selection: Attempts were made to critically evaluate what is known about dentine permeability and adhesion and what remains to be discovered. Speculations were made on a number of controversial issues that are not yet resolved., Conclusions: Acid-etching of dentine produces profound changes in the chemical composition and physical properties of the matrix which can influence the quality of resin-dentine bonds, their strength and perhaps their durability.

Objectives and Methods: The relationship between dentine bonding and the condition of dentine for four dentine bonding systems (All Bond 2, Clearfil Liner Bond, Scotchbond MP and XR Bond) has been examined. Different dentine conditions were evaluated and correlated with adhesion values. Dentine permeability was calculated using a hydraulic pressure apparatus working under physiological pulpal pressure (6.9 kPa), while remaining dentine thickness (RDT) was measured using pincer calipers. Scanning electron microscopic (SEM) examinations were effected to analyse dentine morphology. These evaluations were considered as an index of the condition of dentine. Shear bond strength tests were used to evaluate adhesion. Dentine samples after the bonding systems application were stored for 24 h under pulpal pressure before bond strength was tested., Results: Scanning electron microscopy examinations indicated that the application of bonding system conditioners caused the removal of smear layer, the demineralization of dentine and the formation of a layer of collapsed collagen fibrils in the intertubular and peritubular dentine. Primers were able to infiltrate the collagen fibrils. A layer of resin infiltrated/reinforced dentine (the so-called 'hybrid layer') was observed for All Bond 2, Clearfil Linear Bond and Schotchbond MP., Conclusions: Significant correlations were observed only for XR Bond, which proved very sensitive to RDT and dentine permeability despite the presence of smear layer. The other three materials did not show any correlation with dentine conditions. By contrast they showed the highest bond values.

Freshly extracted third molars were stored for one week in one of four solutions: 70% ethanol, 10% formalin, distilled water with thymol and phosphate-buffered saline with thymol. Crown segments were prepared and initial permeability measurements taken. Each specimen was placed in a fresh preparation of its original solution, and permeability was measured over two periods: 1, 4, 6 and 8 days or 1, 8, 15 and 22 days. Ten crown segments were used for each solution for each time sequence. Permeabilities were lower for those specimens stored in ethanol and formalin than in water/thymol and saline/thymol, but most specimens showed increased permeability with time. Both storage solution and storage time had statistically significant effects (p less than 0.05), with significant differences between specimens stored in water/thymol and saline/thymol and those stored in ethanol and formalin. Thus, type of storage solution effects dentine permeability over time.

Purpose: This study investigated the role of desensitising-only and desensitising/whitening versions of arginine and calcium carbonate-containing (ACC) and calcium sodium phosphosilicate-containing (CSPS) toothpastes on surface loss and permeability of root dentine.Materials and Methods: Slabs of human root dentine were embedded and exposed to citric acid solution to create a lesion resembling hypersensitive dentine. Sixty specimens were divided into six groups and exposed to slurries made with ACC (Colgate Sensitive Pro-Relief) and CSPS (Sensodyne Repair & Protect) toothpastes, in their desensitising or desensitising/whitening versions, an ordinary toothpaste (Crest Cavity Protection) or distilled water (DI). The other 60 specimens were brushed with either slurries or DI and assessed for surface loss. All specimens were analysed for dentine permeability. Data were subjected to analysis of variance (ANOVA) and Fisher's least statistically significant difference tests.Results: ANOVA (p = 0.018) showed that in the group brushed with DI surface loss was lower than in the groups brushed with toothpastes, but there was no statistically significant difference among the ordinary, desensitising-only and desensitising/whitening toothpastes. Dentine permeability was not influenced by brushing (p = 0.125). Toothpastes affected dentine permeability (p = 0.004), with the groups submitted to desensitising-only and desensitising/whitening toothpastes presenting significantly lower permeability than those submitted to DI, but no difference existed between the group treated with the ordinary toothpaste and DI.Conclusion: In comparison to desensitising-only, desensitising/whitening toothpastes neither accounted for increased surface loss nor impaired tubule occlusion of root dentine. [ABSTRACT FROM AUTHOR]

Dentine permeability determinations were made longitudinally in cavities prepared in dog teeth in vivo, using two different techniques: isotope clearance and fluid filtration. Measurements made with both techniques indicate that there is a large reduction in dentine-permeability within the first week following cavity preparation. The phenomenon requires an intact pulp and is not the result of microleakage of temporary restorations.

Cavities were prepared into the dentine of mandibular first molars of anaesthetized dogs. Conical plastic chambers were cemented into the cavities to permit quantitation of dentine permeability using a fluid-filtration technique. There was a progressive fall in dentine permeability every hour for the 6 h of study, to about 20 per cent of zero time values. The fall in dentine permeability could be delayed but not prevented, by filtering fluid across the dentine into the pulp. Similar experiments on teeth from which the pulps had been removed showed no change or a slight increase in permeability with time. No change in dentine permeability was seen in dogs killed after the zero time measurement and followed for an extra 6 h. This decrease of dentine permeability in response to cavity preparations only occurs in teeth with intact pulps.