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PubMed1999

Dentin permeability after toothbrushing with different toothpastes.

PURPOSE: To evaluate the interaction of smear layer produced during brushing and dentifrice particles. MATERIALS AND METHODS: Dentin disks were obtained from extracted human third molars. Dentin permeability was evaluated using a hydraulic pressure apparatus working at 1 psi of pressure. After preparation, each sample was connected to the hydraulic pressure apparatus to evaluate the permeability of dentin with the smear layer produced during specimen preparation. After 5 min of measurements dentin was etched with 37% phosphoric acid gel for 2 min, washed and gently dried with cotton to measure the permeability after smear layer removal. This was done to measure the maximum permeability of each specimen (expressed as 100%). Then a second smear layer was produced using a #400 carbide paper under water for 1 min. Dentin permeability of the smear layer covered dentin was then measured, and expressed as a percent of the maximum permeability of that specimen, permitting each specimen to serve as its own control. The three toothpastes used (Merfluan powder, Merfluan paste and Fluorigard) were applied on dentin surfaces using a small sponge to completely cover the dentin surface. After 5 s, each sample was connected to a mechanical device and brushed under water for 3 min with constant pressure of 250 gr using a Colgate medium toothbrush. After this treatment, each sample was gently washed with tap water, gently air dried for 3-5 s and connected with the pressure apparatus to remeasure the permeability after brushing. For SEM examination of dentin before and after treatment with toothpaste and brushing, each dentin and enamel sample was fixed in 2% buffered glutaraldehyde. RESULTS: Dentin permeability proved unaffected by dentifrice treatments. SEM observations demonstrated the presence of dentifrice particles on dentin surface and inside dentin tubules. Smear plugs produced during dentin brushing were not removed by dentifrices.

Dentin↗
PubMed1984

Effects of air-drying in vitro on human dentine permeability.

The effects of evaporation produced by air blasts of 0, 0.5, 2 or 5 min to dentine in vitro were evaluated by measuring dentine hydraulic conductance before and after each trial. When the tubules were filled with water, even prolonged evaporation had no effect on dentine permeability. Tubules filled with physiological salt solution produced a time-dependent decrease in dentine permeability. Tubules filled with 1.5 per cent albumin in water gave the largest reductions in dentine permeability. These effects were more marked in unetched as opposed to acid-etched dentine. The results suggest that part of the reduction in dentine sensitivity produced clinically by prolonged air blasts may be due to precipitation of organic and inorganic constituents of dentinal fluid at the surface.

Acid Etching, Dental↗
PubMed2003

Effects of Er:YAG and Nd:YAG laser irradiation on radicular dentine permeability using different irrigating solutions.

BACKGROUND AND OBJECTIVES: To evaluate the effect of Er:YAG and Nd:YAG laser on radicular dentine permeability when using distilled and deionized water and 1% NaClO as irrigating solutions. STUDY DESIGN/MATERIALS AND METHODS: Thirty human maxillary canines were divided randomly into six groups. The root canals were instrumented with K files and the step-back technique. Group I, irrigation with distilled and deionized water; Group II, irrigation with 1% NaClO; Group III, irrigation with distilled and deionized water and Er:YAG laser application (140 mJ input, 61 mJ output 15 Hz, 300 pulses, and 42 J); Group IV, irrigation with 1% NaClO and Er:YAG laser application (same parameters as Group III); Group V, irrigation with distilled and deionized water and Nd:YAG laser application (150 mJ, 15 Hz, 2,25 W); Group VI, irrigation with 1% NaClO and Nd:YAG laser application (same parameters as Group V). During laser application the teeth were always filled with the irrigating solution. The tip was withdrawn gently in helicoidal movement from the apex to the cervical portion. The teeth were processed for histochemical evaluation. RESULTS: The Tukey test showed that the cervical and middle thirds were statistically similar (P > 0.05) and significantly greater than the apical third (P < 0.05). The Scheffé test showed significantly greater dentine permeability in root canals in which water and Er:YAG laser were used and were significantly different from the other treatments (P < 0.05). CONCLUSIONS: The use of distilled and deionized water and Er:YAG laser showed the greater increase of dentine permeability. The use of 1% NaClO with Nd:YAG laser, distilled, and deionized water with Nd:YAG laser and the use of water increased dentine permeability less than the other groups. The use of 1% NaClO with and without Er:YAG laser application were positioned intermediately among the treatments.

Dental Pulp Cavity↗
PubMed2004

In vitro assessment of dentinal permeability after the use of ultrasonic-activated irrigants in the pulp chamber before internal dental bleaching.

This in vitro study aimed to assess dentin permeability quantitatively after the use of different irrigants into the pulp chamber, with or without ultrasonic activation, before the application of an internal bleaching agent. Thirty maxillary anterior teeth, treated endodontically, were randomly assigned to six groups, according to the irrigant used: group I, distilled water; group II, 17% EDTA; group III, 1% sodium hypochlorite; for groups IV, V, and VI, respectively, the same solutions were used, but were ultrasonicated. In groups I, II, and III, the irrigant that filled the pulp chamber was left undisturbed for 15 s and was then aspirated; in groups IV, V, and IV, the irrigants were placed into the pulp chamber, ultrasonic-activated for 15 s, and were then aspirated. This sequence was repeated three times for all groups. Afterwards, for all groups, the pulp chamber was dried, filled with a bleaching agent, and sealed with glass ionomer cement. At each change of the whitening agent, these procedures were repeated. Then, the temporary restorations were removed, access cavities were cleaned, and teeth were immersed in a 10% copper sulfate aqueous solution, submitted to vacuum and immersed in a 1% rubianic acid alcohol solution. Copper ion penetration was revealed by the rubianic acid. After staining, roots were removed at the cemento-enamel junction (CEJ) and sectioned in a mesiodistal direction starting from the cervical plug level. The sections were thinned, observed under an optical microscope, the images were digitized, and copper ion penetration was measured in each section using a specific software. Means and SD were: group I, 2.41 (+/-1.45); group II, 5.22 (+/-1.79); group III, 8.32 (+/-2.55); group IV, 3.73 (+/-0.89); group V, 14.83 (+/-4.99); and group VI, 10.51 (+/-2.65). Statistical analysis using two-way anova and Tukey test showed that, regardless of the irrigant, ultrasonication increased dentinal permeability (P < 0.01). Comparing the overall effectiveness of the tested solutions, EDTA yielded the greatest increase in dentinal permeability (P < 0.01). Based on these results, it may be concluded that use of ultrasonic-activated irrigants in the pulp chamber, before the accomplishment of internal dental bleaching procedures, may result in a remarkable increase of dentin permeability, which may enhance the efficiency of the whitening agent.

Chelating Agents↗
PubMed1991

Measurement of dentin permeability and wetness by use of the Periotron device.

The ability of the Periotron device to measure changes in dentin permeability and wetness was evaluated by use of extracted human teeth in vitro. Pulpal pressures were varied from zero to 40 cm H2O for simulation of different pulpal tissue pressures. Non-physiologic pulpal pressures of 703 cm H2O were used for comparison of dentin permeability measurements made with the Periotron device with those made using micropipettes. Measurements made with the Periotron device correlated well with methods used previously for measurement of dentin permeability. The shear bond strength of Scotchbond 2/Silux was measured 24 h after being bonded to dentin held at zero pulpal pressure. There was an inverse correlation between the shear bond strengths of Scotchbond 2/Silux and Periotron values, suggesting that increased wetness decreases the bond strength of that system. The Periotron device offers a new, simple, convenient measure of dentin surface wetness which may be useful in dentin bonding studies.

Adhesiveness↗
PubMed1993

Storage effects on dentin permeability and shear bond strengths.

The effects of duration of storage and selection of storage solution upon dentin permeability and bond strength were studied over a period of 8 days to 6 mon. Teeth were stored immediately after extraction in one of five commonly used solutions: 70% ethanol (E); 10% formalin (F); distilled water (W); distilled water with thymol (WT); or phosphate-buffered saline with thymol (ST). Permeability and lap shear bond strength measurements were evaluated in a repeated measures design (n = 20) after 8 days, 15 days and 6 mon. Dentin permeability varied with solution type and duration of storage as demonstrated by ANOVA, increasing F, E and the water-based solutions, respectively. Saline storage resulted in large significant decreases in permeability after prolonged storage, suggesting changes in dentin. Bond strengths were unaffected by duration of storage or by solution type, except for saline. Thus, permeability and bond strength values may be affected by storage conditions. The results of this study indicate that saline, the most commonly used solution in dental materials research, may be unsuitable for use as a result of its effect on dentin permeability and bond strength.

Analysis of Variance↗
PubMed2001

The use of oxalate to reduce dentin permeability under adhesive restorations.

PURPOSE: To test a novel approach to reducing dentin permeability that localizes occlusion of dentin tubules by calcium oxalate crystals to the subsurface without lowering resin bond strengths to oxalate-treated dentin surfaces. MATERIALS AND METHODS: Flat dentin surfaces of extracted human third molars were etched with a mass fraction of 32% phosphoric acid (Bisco) for 15 s and rinsed. Half of the surface was treated with a potassium oxalate gel (mass fraction of 3% monopotassium monohydrogen oxalate) for 2 mins. The entire surface was then moist bonded with either One Step (OS) or Scotchbond Multi-Purpose (SB) adhesive systems. A resin-based composite (Z-100) buildup was made over the entire surface. After storage for 24 hrs in distilled water, the teeth were longitudinally sectioned to separate the oxalate-treated half from the untreated (control) half. Each half was serially sectioned into several 0.7 mm thick slabs which were then trimmed to an hour-glass shape to reduce the bonded area to approximately 0.8 mm2 and tested in tension. Pre- and post-treatment hydraulic conductance (Lp) of dentin was determined using dentin discs with a standard protocol. SEM images were obtained to examine the effects of treatment both on the dentin surface and along the tubules beneath the surface. The bonded interface was also examined by SEM. RESULTS: Treating etched dentin discs with the oxalate gel caused significant reduction of the Lp of dentin (80% reduction, P < 0.05). There were no statistically significant differences between bond strengths of oxalate-treated and untreated surfaces for either adhesive system. OS resulted in a bond strength of 25.8 +/- 9.2 MPa to untreated and 27.8 +/- 8.9 MPa to oxalate treated surfaces (P > 0.05). SB showed bond strengths of 22.9 +/- 7.9 MPa and 22.9 +/- 9.6 MPa to untreated and treated surfaces, respectively (P > 0.05). SEM images showed that the application of potassium oxalate gel on etched dentin resulted in the formation of crystals inside the tubules rather than on the surface. Examination of the bonded interfaces demonstrated that the crystal formation inside the tubules did not compromise the formation of a typical hybrid layer on the top of dentin surfaces. Resin monomers penetrated into the tubules filling the spaces around the crystals forming resin tags with a jagged-like feature.

Analysis of Variance↗
PubMedDate not supplied

Dentin permeability: effects of crown preparation.

Sequential crown reductions of extracted human teeth were made to evaluate both regional differences in dentin permeability and the effects of tooth reduction. Two different methods of tooth reduction were used. In group 1, tooth reduction was nonuniform but was done in a manner similar to conventional crown preparations. Maximum, total crown permeability was measured using a pressurized fluid filtration technique after removing the smear layer. Regional reductions in permeability were accomplished by creating smear layers on mesial, distal, buccal, lingual, and occlusal surfaces sequentially. Between each step, changes in dentin permeability were measured. In group 2, tooth reductions were uniform and regional permeability was reduced by localized application of potassium oxalate. Both methods demonstrated increased permeability of dentin as the prepared surfaces approached the pulp chamber. Generally, the mesial surfaces were more permeable than the distal surfaces. The occlusal and lingual surfaces were the least permeable regions.

Adult↗
PubMed2007

Evaluation of dentin permeability after light activated internal dental bleaching.

The aim of this in vitro study was to assess quantitatively the dentin permeability of human teeth after intracoronal bleaching therapy with 35% hydrogen peroxide activated by LEDs, halogen lamp or using the walking bleach technique. Forty human maxillary central incisors had standard access cavities performed and the cervical thirds of the canals were prepared with Gates-Glidden drills up to a size 130. Roots were resected between the coronal and middle thirds and the apical portions were discarded. A glass ionomer, 2 mm thick cervical plug was placed inside the canal, at the cement-enamel junction level. Group I received 35% hydrogen peroxide gel activated by LEDs. Group II was submitted to 35% hydrogen peroxide gel activated by halogen lamp. Group III received 35% hydrogen peroxide gel and the walking bleach technique was followed. Group IV (control) received a dry cotton pellet inside the pulp chamber with temporary restoration. Dentinal permeability was quantified by copper ion penetration. Linear measurements were obtained by analysis of digital images under x 5 magnification. Mean values and SD for the experimental groups were: I, 7.1% (+/-3.2%); II, 8.4% (+/-3.0%); III, 9.1% (+/-3.0%); IV, 1.3% (+/-2.8%). One-way ANOVA was used to analyze the results. Results showed an increase of permeability values for groups I, II and III when compared to group IV (control); however, no statistical differences were found between the three tested bleaching techniques. It can be concluded that 35% hydrogen peroxide activated by LED, halogen lamp or used following the walking bleach technique produced similar increase in dentinal permeability.

Dental Pulp Cavity↗
PubMed2003

Effect of internal bleaching agents on dentinal permeability of non-vital teeth: quantitative assessment.

The aim of this in vitro study was to assess quantitatively dentin permeability of pulpless teeth after intracoronal bleaching therapy with three different agents. Twenty-four maxillary central incisors were randomly assigned to four groups according to the bleaching agent used: I--non-bleached control; II--37% carbamide peroxide; III--sodium perborate/20% hydrogen peroxide paste; IV--27% carbamide peroxide. After standard access and root-canal preparation the access opening, biomechanical preparation and root-canal filling, a cervical glass ionomer plug was prepared and intracoronal bleaching procedures were carried out in a standardized fashion. The access cavities were opened and the teeth were externally sealed and immersed in a 10% copper sulfate aqueous solution for 30 min, in vacuum for the first 5 min. Then, samples were removed, dried with absorbing paper and immersed in a 1% rubianic acid alcohol solution, for the same above-mentioned period in solution and in vacuum. Copper ion penetration was indicated by the rubianic acid staining. Mean values and SD for the experimental groups were: I--7.88% (+/-1.33), II--16.94% (+/-5.72); III--11.45% (+/-3.90) and IV--8.98% (+/-4.19). Data were submitted to one-way anova. The results showed that the 37% carbamide peroxide provided the highest increase in dentin permeability, followed by sodium perborate with 20% hydrogen peroxide. The 27% carbamide peroxide provided the lowest results and showed statistical similarity to the control group. On basis of these findings, it may be concluded that, among the tested intracoronal bleaching agents, 37% carbamide peroxide presented an optimized overall performance in increasing dentinal permeability.

Analysis of Variance↗
PubMed1994

Influence of tooth cryopreservation on human dentin permeability, in vitro.

OBJECTIVES: In order to use cryopreserved teeth in laboratory studies, cryopreservation must not modify the functional properties of teeth, in particular dentin permeability. The purpose of this study was to evaluate the effects of tooth cryopreservation on human dentin permeability. METHODS: Three hundred and sixty freshly extracted human noncarious third molars were used. The teeth were randomly assigned to two groups: 180 teeth were stored in phosphate-buffered saline at 4 degrees C and tested within 4 h of collection; 180 teeth were cryopreserved. Hydraulic conductance was calculated according to the method developed by Pashley (Outhwaite et al., 1976). RESULTS: Cryopreserved teeth presented a hydraulic conductance of 8.97 x 10(-3) +/- 4.21 x 10(-3) microL.cm-2.min-1.cm.H(2)0(-1) slightly higher than the hydraulic conductance of the freshly extracted teeth of 8.03 x 10(-3) +/- 3.87 x 10(-3) microL.cm-2.min-1.cm.H(2)0(-1). No statistically significant difference was found between the two groups. SIGNIFICANCE: Under the conditions of this study, cryopreservation did not modify dentin permeability.

Analysis of Variance↗
PubMed1995

Dentine permeability and bond quality as affected by new bonding systems.

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.

Acid Etching, Dental↗
PubMed1996

Relationship between endodontic preparations and human dentin permeability measured in situ.

Endodontic preparations may induce changes in the permeability of radicular dentin. The aim of this study was to analyze the variation of hydraulic conductance measured in situ after three endodontic preparations (manual K+H files, ultrasonic preparation, and manual with NaOCI and EDTA). Scanning electron microscopic analysis of the canal walls was made to permit correlations between variations of permeability and the amount of surface covered with smear layer or organic debris. There was an inverse relationship between the variations in dentin permeability and the presence of smear layer. The significance of this correlation was variable according to the techniques used. Dentin thickness was as significant a factor in influencing radicular permeability as was the smear layer. The use of EDTA induced a considerable increase in radicular permeability. The use of ultrasonics produced a similar but weaker effect.

Analysis of Variance↗
PubMed1991

Effects of high-speed cutting on dentin permeability and bonding.

The effects of high-speed cutting by use of a diamond bur with or without water coolant or sanding by 80-grit SiC paper on dentin permeability, before and after surface treatment, and dentin bonding of adhesive resins were compared. Three different bonding systems were used: Scotchbond DC, which requires no removal of smear layers, and two others, Clearfil Photobond and Superbond C&B, both of which remove smear layers (phosphoric acid gel or 10% citric acid containing 3% ferric chloride, respectively). Creation of smear layers by bur cutting or sanding reduced dentin permeability to levels that were only 1-3% of the maximum permeability values. Scotchbond DC gave low but consistent bond strengths (3.7-6.1 MPa) to dentin covered with smear layers. Clearfil PHotobond also produced consistent bond strengths (8.6-9.4 MPa). The increase in the permeability of dentin after phosphoric acid treatment was higher when the SiC paper was used (146%) than when the high-speed bur was used (87-90%). The smear layer and smear plugs produced by the diamond bur were more resistant to 10-3 treatment than were the SiC-created smear layers. The bond strengths of Superbond showed the highest bond strengths to the conditioned dentin when the high-speed cutting was used with water coolant (16.3 MPa), compared with the other two groups (12.2-12.5 MPa).

Analysis of Variance↗
PubMed1987

The efficacy of resin-compatible cavity varnishes in reducing dentin permeability to free monomer.

The effectiveness of three resin-compatible cavity varnishes in reducing the dentin permeability to free monomer liquid was evaluated by means of a dentin disk mounted within a pressurized split-chamber diffusion device filled with low-viscosity aliphatic dimethacrylate. Substantial reduction in dentin permeability was obtained with all of the products tested (Microjoin, Cavi-Line, and Universal). This study suggests their likely effectiveness as a protective barrier against permeation of free monomer into the dental pulp.

Collodion↗
PubMed1993

Effects of dentin permeability and hydration on the bond strengths of dentin bonding systems.

This in vitro study evaluated the shear bond strengths of five adhesive systems bonded to dentin with and without simulated physiologic hydrostatic pressure. To simulate pulpal pressure, bonding procedures were done on extracted teeth connected to a hydration apparatus. Bond strengths were significantly less for each adhesive system under simulated physiologic conditions. Amalgambond had significantly higher bond strengths than Clearfil Photo Bond, Gluma, Scotchbond 2, or Tenure, either with or without simulated pulpal pressure.

Analysis of Variance↗
PubMed2006

Effect of simulated pulpal pressure on dentin permeability and adhesion of self-etch adhesives.

OBJECTIVES: Dentin bonds made with one-bottle etch-and-rinse and self-etch adhesives are affected by the formation of interfacial blisters, porosities and deterioration. The first objective of this study was to evaluate the fluid flow through resin-dentin interfaces created by self-etching adhesives applied to deep dentin using a replica technique and by directly measuring dentin permeability (P). The second objective was to examine the effect of intrapulpal pressure on the microtensile bond strength of these adhesives. METHODS: A fluid-transport model was used to measure the fluid permeability (%P) through different adhesives. Impressions of bonded dentin were taken with a polyvinylsiloxane impression material to monitor fluid transudation from the surface of the adhesive. Positive replicas were fabricated for SEM examination. Two groups of resin-bonded specimens (pulpal pressure versus no pulpal pressure) were created for microtensile bond strength evaluation. Adhesive application was performed under 0 cm H(2)O. Pulpal pressure group was submitted to 20 cm H(2)O of pulpal pressure during build-up procedures. RESULTS: Clearfil Protect Bond exhibited the lowest permeability and fewest numbers of fluid droplets over the surface of the bonded dentin. G-Bond and Clearfil-S3 Bond were more permeable than Clearfil Protect Bond. One Up Bond F was the most permeable adhesive. A highly significant correlation was observed between the relative permeability of these adhesives (%P) and the number of fluid droplets on the adhesive surfaces. The application of pulpal pressure significantly reduced bond strength. SIGNIFICANCE: Resin-dentin bonds created by contemporary self-etch adhesives are susceptible to fluid permeation induced by pulpal pressure. HEMA-based adhesives showed the largest reductions in bond strengths after pulpal pressure application.

Acid Etching, Dental↗
PubMed1989

Dentin permeability and bond strengths after various surface treatments.

Numerous reports suggest that removal of the smear layer increases the bond strengths of some dentin adhesives while lowering the bond strengths of others. Smear layer removal also increases dentin permeability and wetness. The purpose of this study was to compare the permeability and shear bond strengths of occlusal vs. buccal dentin before and after removal of the smear layer with 6% citric acid and before and after substitution of the smear layer by topical oxalate treatment. Shear bond strengths of Scotchbond/Silux to smear layers were higher than those to acid-etched dentin. Oxalate treatment of acid-etched dentin increased bond strengths to levels that were higher than smear layer controls. Removal of the smear layer increased dentin permeability. This result was completely reversed by oxalate treatment.

Acid Etching, Dental↗