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Purpose: To evaluate the effect of different varnishes on dentin permeability to erosive/abrasive challenges., Methods: 60 superficial dentin discs were randomly allocated to six groups (n=10): Duraphat, PRG Barrier Coat, Clinpro XT, Profluorid, Fluor Protector S and untreated (control). Permeability tests were carried out: after acid conditioning, after treatment, and after abrasive/erosive challenges. The abrasive-erosive challenges were performed for 5 days (citric acid and in remineralizing saliva), as well as abrasion with toothpaste slurry (Colgate Total 12). Scanning electron microscopy (SEM) images were obtained of the dentin surfaces (5,000x) after the treatments, and after the erosive/abrasive challenges., Results: Kruskal-Wallis and Dunn tests showed that all the varnishes promoted a decrease in dentin permeability directly after application, with Clinpro XT showing the highest percentage (69.52%) of dentin sealing (P= 0.0188). After the erosive/abrasive challenge, only PRG Barrier Coat varnish showed dentin sealing ability with reduced dentin permeability (42.16%) (P= 0.0014). However, none of the applied varnishes promoted a statistically significant difference in the percentage of dentin sealing, compared with the control group (P> 0.05). Clinpro XT showed a higher percentage of dentin sealing, while only PRG Barrier Coat showed reduced dentin permeability after the erosive/abrasive challenge., Clinical Significance: Varnish containing S-PRG filler has the efficacy needed to be used as a coating material to reduce dentin permeability in situations of erosive/abrasive challenges., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To characterize, in vitro, the mode of action of stannous fluoride containing formulations in occluding dentin tubules, by means of high resolution microscopy techniques., Methods: Focused ion beam scanning electron microscopy (FIB SEM) was used to site-specifically prepare cross sections for SEM and TEM imaging and analysis of dentin samples treated with either a stannous fluoride dispersion in glycerol or an experimental stannous fluoride dentifrice., Results: An experimental stannous fluoride dentifrice formed a protective layer over the dentin surface and occluded dentin tubules. Additional supporting data derived from a stannous fluoride dispersion in glycerol suggest that stannous fluoride is a key component of this occluding system. Multiple SEM images obtained from sequential FIB cross-sections were reconstructed into 3-dimensional tomograms that showed a formed layer and tubule occlusion. Sections thinned by FIB techniques were observed by transmission electron microscopy (TEM) and related methods and showed that the coating, which was up to 3 microm-thick, consisted of a tin containing precipitate. Chemical analysis by energy dispersive x-ray spectroscopy (EDS) mapping that used scanning TEM (STEM) methods showed interdiffusion of tin up to 200 nm into the dentin structure.

Purpose: To determine the effect of acid etching time on dentin calcium solubilization and to compare the solubilization rate of primary and permanent dentin when etched for the same period of time., Methods: Flat coronal dentin surfaces were produced on primary (n=8) and permanent (n=8) sound teeth. Three 2 mm-diameter areas were delimited on each surface and assigned to 5, 10 or 15 seconds of acid etching. Five microliters of 35% H3PO4 were applied on each area during the preset times, and 4 microL were retrieved for analysis. The amount of calcium was determined colorimetrically using Arsenazo III reagent and expressed as microg Ca/mm2 of dentin. Data were subjected to two-way ANOVA, Tukey's test and linear regression (alpha=5%)., Results: For both primary and permanent dentin, a statistically significant correlation was observed between acid etching time and calcium concentration (primary dentin R2 = 0.79; permanent dentin R2 = 0.73). Mean (sd) values of dissolved primary dentin after 5, 10 and 15 seconds were 1.00 (0.25), 1.74 (0.11) and 2.30 (0.42), whereas for permanent dentin the values were 0.47 (0.13), 0.89 (0.36) and 1.38 (0.20) microg Ca/mm2, respectively. Greater calcium solubilization (P<0.05) was detected for primary dentin than for permanent dentin after all acid etching times.

Purpose: To identify the remaining demineralized dentin (the permeable layer that allows leakage) when using primer-less wet bonding with a total etching period of 10 to 60 seconds compared with contemporary resin adhesives., Methods: Extracted human molars were selected and Class V cavities were prepared on the axial surfaces at the CEJ, providing margins in enamel and dentin for leakage testing using a basic dye (n = 10). Seven groups of conditioned teeth [1-1 etched for 10, 30, and 60 seconds (primer-less wet), All-Bond 2 and Single-Bond 2 (wet), AQ-Bond (self-etched), Super-Bond C&B (dry)] were used as bonding systems for resin composite restoration. All specimens were stored in water at 37 degrees C for 24 hours before soaking in a 0.5% basic fuchsin solution for 24 hours. The distance of dye penetration was measured using stereomicroscopy., Results: No leakage at the enamel- and dentin-resin interfaces was found for all etching periods of 1-1 primer-less, Super-Bond C&B, and AQ-Bond specimens. However, leakage was observed at dentin margins in two wet with primer systems, All-Bond 2 (1.31 +/- 1.39 mm) and Single-Bond 2 (0.37 +/- 0.28 mm), which required phosphoric etching to remove a weak smear layer on prepared dentin.

Purpose: To evaluate the bond strength of resin dentin interfaces created with adhesives applied on root dentin using the water wet or ethanol wet bonding technique. The morphology of resin dentin interfaces was evaluated using confocal microscopy., Methods: Four experimental resin adhesives (R#A to R#D) and one commercial three-step/etch and rinse adhesive were applied to the root canal dentin of endodontically treated single canal incisors using the water (control) or ethanol wet bonding technique. The ethanol wet bonding substrate was achieved by keeping the root canal immersed in absolute ethanol (100%) for 3 minutes. The root dentin bonded specimens were sectioned into beams, stored in distilled water (24 hours) and finally tested for microtensile bond strengths (tTBS). Additional dentin surfaces were conditioned and bonded as previously described. They were prepared for the microscopy study and finally observed using confocal microscopy., Results: The ethanol wet bonding technique gave higher bond strength values for all the adhesives tested: in Group 1 (water wet bonding technique) no significant difference was found between the resins tested; the only exception being the most hydrophilic Resin #4 showing the highest bond strength values (P < 0.05). In Group 2 (ethanol wet bonding technique) no statistical differences were present between Resin #A and Resin #D. Resin #C showed the highest bond strength values. Confocal microscopy showed better resin diffusion and hybrid layer formation when the ethanol wet bonding was used.

Purpose: To evaluate the effect of etching time on the nanoleakage and microtensile bond strength (microTBS) at the interface between etch-and-rise adhesives and dentin., Methods: Eighty molars were sectioned to expose the superficial dentin and randomly divided into four groups according to the adhesives used: OptiBond Solo (OB), Single Bond (SB), One-Step (OS), and Prime&Bond NT (PB). Within each group, a total-etching technique was applied, and the dentin surfaces were etched for 0, 15, 30 or 60 seconds. Each treated tooth was then sectioned into sticks. A non-trimming microTBS test and TEM observation for nanoleakage were sequentially performed., Results: The degree of nanoleakage increased as etching time increased (P < 0.05). For the OS and PB groups, the highest microTBS values were achieved with 15 seconds of etching, followed by 30, 60 and 0 seconds. For the OB and SB groups, the microTBS values for 15- and 30-second etching times were similar and were both significantly higher than those of 0 and 60 seconds (P < 0.05).

Purpose: To evaluate the stability of the interfacial layer and leakage patterns between enamel, DEJ, dentin and three adhesive systems as demonstrated by either a dye or a silver nitrate technique to understand the marginal integrity of restored tooth substrates., Methods: Extracted human molars were cross-sectioned to prepare enamel, DEJ and dentin surfaces. Areas with the DEJ aligned in the middle were restored with prefabricated flat composite blocks using either Superbond C&B (SB), Panavia Fluorocement (PN) or Variolink II (VL) cements. 7 restored specimens for each cement were prepared to investigate the interfacial layer after chemical challenge using SEM. Restored and control specimens for each cement were prepared for leakage tests by soaking either in 0.5% basic fuchsin or 50% silver nitrate solutions for 24 hours (n = 8). The penetration depth of tracer was measured using stereoscopy and a digital micrometer. SEM backscattered electron image and energy dispersive x-ray spectrometry were used to detect the location of the silver., Results: Prepared SB hybridized enamel, dentin and DEJ were stable against soaking in HCl followed by NaOCl solutions whereas prepared DEJ- and dentin-resin interfacial layers were degraded, detached and thinner than that of enamel in VL and PN specimens. No leakage was found at the enamel-resin interface for all cements and at the DEJ- and dentin-resin interfaces for SB specimens. VL specimens showed significantly greater leakage at the interface of dentin and DEJ than did PN specimens.

Purpose: To evaluate the antibacterial effect of different chlorhexidine (CHX) concentrations against Streptococcus mutans using the agar-diffusion method with and without human dentin discs placed between the bacteria and the test substances., Methods: For the direct application (agar-well technique), a base layer containing 15 mL of BHI agar and 300 microL of S. mutans inoculum (10(9) cfu/mL) was prepared in Petri dishes. Six wells per dish were made at equidistant points and immediately filled with CHX gels (0.12%, 0.2%, 1% and 2%), 35% phosphoric acid and pure natrosol (n = 6 wells/substance). Paper discs soaked in sterile distilled water served as control group (n = 6). For the indirect application (transdentinal diffusion), 0.2 mm- and 0.5 mm-thick human dentin discs (36 discs/thickness) had the hydraulic conductance determined, which allowed the homogeneous allocation of them to the experimental and control groups. The discs were placed at equidistant points on the Petri dishes containing BHI with the S. mutans inoculum (six discs per dish; one per substance) with the pulpal side in contact with the bacteria. In the discs treated with CHX gels, dentin surface was etched with H3PO4 and rinsed with distilled water before CHX gel application for 1 minute. After both direct and indirect application, the dishes were incubated for 24 hours and the bacterial growth inhibition zones formed around the wells and dentin discs were measured. Data were analyzed statistically by the non-parametric Kruskal-Wallis and Mann-Whitney tests at 5% significance level., Results: In the direct test, all CHX concentrations presented a dose-dependent antibacterial activity against S. mutans. In the indirect test, there were statistically significant differences (P < 0.05) among all groups and the largest microbial growth inhibition zones were observed when 2% CHX was applied on 0.2 mm-thick discs (P < 0.05). It was concluded that all evaluated CHX gels exhibited both direct and transdentinal antibacterial activity against S. mutans. This effect of CHX was strongly influenced by the CHX concentration as well as the dentin barrier thickness.

Purpose: To evaluate the influence of dentin etching with phosphoric acid on hydrogen peroxide diffusion through human dentin in internal bleaching., Methods: 46 human premolars were extracted for orthodontic reasons from adolescents. The teeth were endodontically treated and a flat defect was created at the enamel-cementum junction. The teeth were divided into two groups: the access cavity was etched for 30 seconds with 35% H3PO4 in the first group and left intact in the second group. The teeth were filled with 20 microL of 35% hydrogen peroxide gel. The receiving medium on the other side was renewed at Day 1, Day 2 and Day 7 to quantify the diffusing hydrogen peroxide. An analysis of variance was performed to compare the diffusion between the two groups., Results: This work demonstrated a higher hydrogen peroxide diffusion when the access cavity was etched (P < 0.01).

Purpose: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique., Methods: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml., Results: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.

Purpose: To provide a brief overview of the diagnosis, epidemiology, etiology and clinical management of dentin hypersensitivity, to discuss technical approaches to relieve sensitivity, with special emphasis on dentin tubule occlusion and the clinical evidence for efficacy of desensitizing toothpastes based upon this approach, and to summarize the science behind a new dentifrice technology, based upon arginine and calcium carbonate, and the clinical evidence which proves that it delivers both instant and lasting relief of dentin hypersensitivity., Results: Clinical studies have shown that a new toothpaste, containing arginine and calcium carbonate (known as Pro-Argin technology) with 1450 ppm fluoride, offers clinically proven instant and lasting relief of dentin hypersensitivity. Three 8-week clinical studies have shown that this new toothpaste provides statistically significantly superior efficacy in reducing sensitivity to market leading desensitizing toothpastes containing 2% potassium ion. Importantly, three further clinical studies have shown that a single direct topical application of toothpaste to sensitive teeth, using a fingertip or cotton swab followed by 1 minute of massage, resulted in instant relief of dentin hypersensitivity and that the relief was maintained with subsequent twice-daily brushing. Mechanism of action studies have shown that this technology physically seals dentin tubules with a plug that contains arginine, calcium carbonate and phosphate. This plug, which is resistant to normal pulpal pressures and to acid challenge, effectively reduces dentin fluid flow and thereby relieves sensitivity. A new whitening variant of this desensitizing toothpaste, containing the Pro-Argin technology, fluoride and a high cleaning calcium carbonate system, has now been clinically and scientifically validated. This toothpaste works by the same mechanism of action as its non-whitening counterpart and is clinically proven to provide both instant and lasting relief of sensitivity, while providing proven efficacy in removal of extrinsic stains. No difference in desensitizing efficacy was observed between the whitening and non-whitening versions.

Purpose: To identify how different treatments of the root dentin surface affect the microscopic appearance of the resin composite/glass-ionomer cement-to-dentin interface., Methods: The root canals of 70 extracted human single-rooted teeth were enlarged to reduce dentin wall thicknesses to 0.5 mm. The roots were randomly divided into seven test groups (n=10) according to the canal irrigant used: no irrigant (control), 5% hydrogen peroxide, 5% sodium hypochlorite, a combination of 5% hydrogen peroxide and sodium hypochlorite, 15% ethylenediaminetetraacetic acid (EDTA), 10% lactic acid, or 20% lactic acid. To simulate thin-walled roots, within each group, crowns were sectioned and the entire surface of each root canal space was enlarged with Profile instrument. Half of treated root canals (n=5) were filled with resin composite (PermaFlo) and the other half were filled with glass-ionomer cement (Fuji II LC). A light-transmitting plastic post (Luminex) was used to create space for a fiber-reinforced post and to ensure polymerization of the restorative material. Specimens were critical-point dried and freeze fractured for scanning electron microscope analysis. Three sites along the root were evaluated (cervical, middle, and apical)., Results: Scanning electron micrographs showed no differences in the morphology of the resin tags at the cervical, middle or apical levels with any of the irrigants or the restorative materials used. Also, no difference in surface topography was found within individual groups. A resin-dentin interdiffusion zone and resin tags developed after application of resin composite with lactic acid solutions and EDTA but not with the glass-ionomer cement.

Purpose: To evaluate the effect of water storage on the microtensile dentin bond strength of one total-etch and four self-etching adhesives to dentin., Methods: The adhesive materials were: one total-etch adhesive (Admira Bond) and four self-etch adhesives (Clearfil S tri Bond, Hybrid Bond, Futurabond NR, Adhe SE). Freshly extracted human third molar teeth were used. For each tooth, dentin was exposed on the occlusal surface by cutting with an Isomet saw and the remaining part was mounted in a plastic ring using dental stone. After adhesive application, a composite resin (Grandio) was placed in 5-6 mm height to form a crown segment. For each tested adhesive, two test procedures (n=6 teeth) were carried out. Procedure A: the teeth were stored in water for 24 hours, and then sectioned longitudinally, buccolingually and mesiodistally to get rectangular beams of 1 +/- 0.1 mm thickness on which a micro-tensile test was carried out. Procedure B: The specimens were stored in water at 37 degrees C for 3 years before sectioning and microtensile testing. During microtensile testing the beams were placed in a universal testing machine and load was applied at cross-head speed of 0.5 mm/minute., Results: For the 24-hour water storage groups, there was no significant difference in the bond strength between the different adhesives. After 3 years of water storage, the bond strength of all self-etch adhesives was significantly reduced compared to the control groups (24 hours). In contrast, the bond strength of Admira Bond was not significantly reduced.

Purpose: To find the most appropriate Er:YAG laser parameters for an optimal marginal adaptation of Class V restorations in enamel and dentin., Methods: Six saucer-shaped mixed Class V cavities were prepared in each of the eight experimental groups with an Erbium:YAG hard laser (Opus Duo) on extracted human molars in near contact mode with a conical 800 microm sapphire tip under continuous water spray by using different pulse energy and pps (pulse per second) parameters. The cavities were restored under the simulation of dentin fluid with Clearfil SE Bond and Clearfil APX PLT composite applied in two layers and light-cured. Marginal adaptation in enamel and dentin was quantified before and after simultaneous thermal (5-50-5 degrees C, 2 minutes each) and mechanical (max. 49N; 1,200,000 cycles) stresses by using the replica technique in a SEM under x200 magnification., Results: With the exception of dentin margins before loading, significant differences for percentages of "continuous margin" and "enamel fractures" were detected before and after loading (P < 0.05, ANOVA, Student's t-test). A pulse energy of 100 mJ both on dentin and enamel was found optimal for finishing and smoothing the preparation margins after cavity preparation with 500 mJ or more.

Purpose: To evaluate the bond strength and micromorphology of the fracture pattern of adhesive composite restorations in primary teeth after long-term clinical function., Methods: Subjects (8-10 years-old) with deep carious lesions in primary molars had their teeth restored with resin composite (Z250). The teeth were randomly divided into two groups, according to the adhesive system used: (1) Scotchbond Multi-Purpose (SMP); and (2) Clearfil SE Bond (CSE). After the clinical and radiographic follow-up period (15-17 months), the teeth were exfoliated and the adhesive restorations were subjected to microtensile bond test., Results: Student's t-test revealed a statistical difference (P= 0.001) between the two adhesive systems tested (SMP = 16.8 +/- 2.62 MPa; CSE = 27.3 +/- 2.28 MPa). The micromorphology evaluation of the failure zone revealed a weak area in the demineralized dentin (SMP) and at the top of the hybrid layer (CSE).

Purpose: To evaluate the clinical outcome of composite restorations performed in primary molars after 18 months and the morphology of the dentin/resin interface., Methods: 41 primary molars from children aged 4-9 years were restored with Scotchbond Multi-Purpose Plus adhesive system and Z100 resin-based composite. The restorations were evaluated at baseline, 6, 12 and 18 months using the USPHS method for direct clinical analysis. Plaster models were made at each evaluation period for indirect evaluation. For the morphologic analysis of the dentin/resin interface, seven exfoliated teeth were sectioned longitudinally in a mesio/distal direction and observed in the electro scanning electron microscope., Results: 100% (n = 40) of the restorations evaluated at 6 months were scored as Alpha for anatomical form, color matching, secondary caries, color alteration, and marginal degradation. At 12 months, 96.4% (n = 28) of the restorations received Alpha score and 3.4% Charlie score. At 18 months, all restorations evaluated (27/27) received Alpha score. 23 restorations were indirectly evaluated at 6, 12 and 18 months postoperatively. No significant wear or fractures were observed in any of the restorations. In the evaluation of the dentin/resin interface, the formation of a consistent hybrid layer was observed and the restorations were well adapted to the dentin at 18 months postoperatively.

Purpose: To evaluate in vitro HEMA diffusion amounts from three dentin-bonding systems in primary molars with various remaining dentin thicknesses., Methods: Occlusal cavities were prepared with remaining dentin thickness of 0.5, 1 and 2 mm respectively. Chambers that contain 1 ml of distilled water were attached to each tooth. The groups were treated with Total Etch + Syntac Single Component, Syntac Single Component and Clearfil SE Bond. Water eluates were removed after 72 hours for analyses by HPLC., Results: The cumulative HEMA release amounts were significantly different between all groups (P< 0.05). Decreasing dentin thickness and acid-etching significantly increased pulpward diffusion of HEMA.

Purpose: To evaluate the bonding durability of a self-etching primer system to normal and caries-affected dentin under hydrostatic pulpal pressure., Methods: 18 extracted human molars with occlusal caries were used. Their occlusal dentin surfaces were ground flat to expose normal and caries-affected dentin using #600 SiC paper under running water. Clearfil SE Bond was placed on the dentin surface including the caries-affected dentin according to the manufacturer's instructions and then the crowns were built up with resin composite (Clearfil AP-X) under either a pulpal pressure of 15 cm H2O or none (control). The bonded specimens were stored in 100% humidity for 1 day (control) or for 1 week and 1 month with hydrostatic pulpal pressure. After storage, the specimens were serially sectioned into 0.7 mm-thick slabs and trimmed to an hour-glass shape with a 1 mm2 cross-section, isolated by normal or caries-affected dentin, and then subjected to the micro-tensile bond test. Data were analyzed by two-way ANOVA and Tukey's test (P< 0.05)., Results: Hydrostatic pulpal pressure significantly reduced the bond strength to normal dentin after 1-month storage (P< 0.05), but did not affect the bond strength to caries-affected dentin.

Purpose: One-step self-etch adhesives have restricted use due to their acid-base incompatibility with autocured composites and their behavior as permeable membranes after polymerization. This study examined the feasibility of their conversion to two-step self-etch adhesives via the adjunctive use of a non-solvented, relatively hydrophobic resin coating., Methods: iBond, Xeno III and Adper Prompt were used either in multiple coats, or in a single coat followed by the use of a layer of Scotchbond Multi-Purpose Plus bond resin for coupling to light- and auto-cured composites. Four types of experiments were performed. Bonded specimens were examined with TEM after immersion in an ammoniacal silver nitrate tracer. Fluid flow measurements of iBond were conducted using the two application protocols to compare the permeability of the bonded dentin with the original smear layer. Permeability of vital dentin bonded with both application protocols were compared for the transudation of dentin fluid across the bonded dentin. Microtensile bond strengths of dentin bonded with the two protocols were examined for their compatibility with an auto-cured composite., Results: The results of the four experiments were complementary. iBond and Xeno III exhibited "apparent incompatibility" to auto-cured composites that resulted from their inherent permeability. This was confirmed by the presence of dentin fluid transudate on the adhesive surfaces when they were bonded to vital dentin. Conversely, Adper Prompt exhibited "true incompatibility" to auto-cured composites that was caused by adverse acid-base interaction, masking the inherent permeability of this adhesive. "True" and "apparent" incompatibility issues were eliminated upon their conversion to two-step self-etch adhesives.

Purpose: To evaluate the hybrid layers in interfaces between dentin and six contemporary one-bottle adhesive systems using a nondestructive differential staining micro-technique., Methods: The adhesive systems used in this study were divided to three groups based on hydrophilic/hydrophobic component ratios (i.e. ability to dissolve in water), from highest to lowest as follows: Group 1 (Dentastic UNO.DUO, PermaQuick PQ1) > Group 2 (One-Step, Primer&Bond NT) > Group 3 (Optibond Solo, Single Bond). The occlusal third of the crown was removed from 36 extracted, unerupted human 3rd molars. Smear layers were created by abrading the dentin with 600 grit SiC under water. The exposed dentin was treated with one of the adhesive systems per manufacturer's instructions. After 24 hours in water, 3-5 microm thin sections of the adhesive/dentin (adhesive/dentin ) interface were cut with a microtome and stained with Goldner's trichrome. Stained thin sections from each prepared tooth were imaged with light microscopy., Results: The thickness and color difference of adhesive/dentin interfaces among these one-bottle adhesive systems were clearly visualized. The width of the hybrid layers varied, ranged from 4.1-9.2 microm for six adhesive systems. The color differences in the stained sections are reflected to the extent and degree to which the adhesive envelops the exposed collagen. Among these six bonding systems, resin encapsulation of collagen varied from highest to lowest as follows: Group 1 (UNO, PQ1) > Group 2 (OS, PBNT) > Group 3 (OP, SB). The differences in collagen encapsulation are dependent on the adhesive composition, or the ability to tolerate water during the infiltration of the wet demineralized matrix.

Purpose: To evaluate the microtensile bond strength (MTBS) of a resin-based composite to smear layer-covered dentin using a self-etching primer, Clearfil SE Bond (CSEB), under two different hydration states. Surface roughness and wettability (contact angle measurements) of water and the CSEB primer were also evaluated on this substrate., Methods: Contact angle (CA) measurements were performed on four caries-free extracted human third molars. The specimens were sectioned parallel to the occlusal surface to expose the moderately deep dentin and ground flat (180-grit SiC) under water to provide uniform flat surfaces. In two samples, the smear layer was completely air-dried; in the other two specimens, the smear layer was briefly air-dried. Contact angle measurements were performed to assess wettability of water and CSEB primer using the Axisymmetric Drop Shape Analysis technique. Surface roughness (SR) was determined with a contact profilometer. In another four molars, CSEB was applied to the smear layer-covered dentin with both hydration states. Resin build-ups were performed incrementally with Tetric Ceram. After storage for 24 hours in water at 37 degrees C, the teeth were sectioned to obtain bonded beams with an average cross-sectional area of 1.0 mm2. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Kolmogorov-Smirnov and Student t-tests were performed at a 95% significance level., Results: Observed water contact angles were lower on the hydrated smear layer but no differences were found between contact angles on completely and briefly air-dried smear layer when the primer was used for CA measurements. SR was similar for both substrates and MTBS was greater when the adhesive was applied on the completely air-dried smear layer.

Purpose: To compare nanoleakage patterns of an unfilled (OS; One-Step), a 6 wt% spherical silica-filled (OSs; One-Step Plus) and a 15 wt% glass-filled (OSg) version of a two-step, acetone-based self-priming adhesive. Permeability of bonded dentin treated with OS and OSs was also examined., Methods: Deep, coronal dentin from extracted third molars were etched and bonded using these adhesives. One-mm thick sections were immersed in 50 wt% ammoniacal silver nitrate (pH 9.5) for 24 hours. Unstained, undemineralized sections were examined by TEM. The permeability of dentin bonded with OS and OSs were investigated at 20 cm of H2O hydrostatic pressure and compared with the osmotic conductance determined with 4.8 M CaCl2 at zero hydrostatic pressure. Composite-dentin beams bonded with OS, OSs and OSg that were fractured after microtensile bond testing were examined by SEM., Results: Two types of nanoleakage patterns were recognized along the resin-dentin interfaces. The reticular type consisted of discontinuous islands of silver deposits and was exclusively seen in hybrid layers. The spotted type consisted of isolated silver grains and was evident throughout the hybrid and adhesive layers in OS. These two patterns were seen to variable extents in the two filled adhesive versions OSs and OSg and their distribution was independent of one another. OS and OSs bonded dentin were permeable to fluid filtration. However, part of this fluid movement was due to the permeability of the adhesive layer, as demonstrated by osmotic fluid conductance in the absence of hydrostatic pressure. Fractographic analysis revealed denuded collagen fibrils within fractured hybrid layers that were indicative of incomplete resin infiltration.

Purpose: To apply a vibration technique to compare the bond strength and resin penetration depth into the dentin tubules with those gained using conventional techniques., Methods: Eighty-eight noncarious extracted human permanent molar teeth were sectioned to remove the coronal enamel. They were embedded in a 1-inch PVC pipe with an acrylic resin. The occlusal surfaces were placed so that the tooth and the embedding medium were at the same level to form a single flat surface. The samples were subsequently polished with silicon carbide abrasive papers, and randomly assigned to four groups (n=22). In Groups 1 and 2, Single Bond was used, and in Groups 3 and 4, One-Step was used. Each adhesive system was applied according to its manufacturer's instructions. For Groups 2 and 4, vibration was applied with an ultrasonic scaler for 10 seconds, and the adhesive was light-cured for 10 seconds. The resin composite was condensed onto the prepared surface in two increments using a Teflon mold and each increment was light-cured for 40 seconds. After 24 hours soaking in tap water at room temperature, the specimens were thermocycled, and the shear bond strengths were measured using a universal testing machine. One-way ANOVA test followed by Student-Newman-Keuls test (P < 0.05) were used to analyze the results. To investigate the infiltration patterns of the adhesive materials, the surface of the specimens was examined with electron microscopy., Results: The shear bond strengths of the vibration groups (Groups 2, 4) were significantly higher than those of the non-vibration groups (Groups 1, 3). The shear bond strengths of Single Bond and One-Step were not significantly different. The vibration groups showed greater numbers of resin tags in the tubules and lateral branches under SEM than the non-vibration groups.

Purpose: To compare teeth prepared to receive a metallic versus a metal-ceramic crown with respect to (1) in vitro dentin permeability before and after using a desensitizing agent and (2) pulpal eugenol concentration after sealing a temporary crown with a zinc oxide-eugenol based cement., Materials and Methods: The roots of 20 human mandibular molars were separated and the crowns were prepared to receive a metallic crown. The hydraulic conductance was recorded before and after using Protect dentin desensitizer. The crowns were then further reduced to receive a metal-ceramic crown and the hydraulic conductance was recorded under the same conditions, on deeper dentin, before and after using the desensitizing agent. Twenty additional teeth were prepared: 10 to receive a metallic crown and 10 teeth to receive a metal-ceramic crown. A tube filled with 1 mL phosphate buffered saline (PBS) was sealed to the cementoenamel junction. A temporary crown was sealed onto the preparation with Temp Bond. The amount of eugenol that diffused across dentin into PBS was spectrofluorimetrically measured at Day 1 and Day 7. The crown preparations were vertically sectioned and the dentin remaining thickness was recorded., Results: The hydraulic conductance of teeth prepared for a metal-ceramic crown was twice as high as teeth prepared for a metallic crown (P < 0.001). The desensitizing agent reduced the hydraulic conductance in both groups (P< 0.001). The two groups showed the same hydraulic conductance after using Protect (ns). No significant difference was found in the amount of eugenol diffusion between the two groups of teeth although eugenol diffusion decreased with time (P < 0.01). No correlation was found between eugenol diffusion and remaining dentin thickness.

Purpose: To compare by confocal and scanning electron microscopy the post-resin-dentin interfaces of endodontically-treated teeth which had been restored with dentin-bonding systems and composite and needed to be extracted after 6 months to 6 years of clinical service., Materials and Methods: Sixteen single rooted teeth showing proximal lesions penetrating the pulp chamber were included in the investigation and divided into two groups. Group 1 teeth were endodontically-treated, restored with carbon fiber posts and resin-based composite. Group 2 teeth were treated in the same way and covered with porcelain fused-to-metal crowns., Results: Two thirds of the observed interfaces showed resin penetration of the root dentin in the middle and coronal third of the post space preparation, while only one third of the interface showed resin infiltration in the apical third of the post space preparation. Debonding of the adhesive from the resin infiltrated dentin area and debonding of the composite cement from the adhesive were the most frequently observed failure modes and were observed in one third of the observed interfaces. There was no difference between the post-resin-dentin interfaces of teeth covered and teeth not covered with porcelain-fused to metal crowns. Teeth extracted after longer periods of clinical service showed more abundant areas of debonding of the adhesive from the resin-dentin interdiffusion zone. The presence of bacteria in resin infiltrated dentin tubules was observed in two specimens.

Purpose: To evaluate the bond strengths of two different types of resin bonding systems to coronal dentin and dentin of the pulp chamber floor., Materials and Methods: 20 extracted human molars were sectioned into three regions; superficial coronal dentin, deep coronal dentin and floor of pulp chamber dentin. The dentin surface of each region was bonded with Single Bond or Clearfil Liner Bond 2V. A core build-up light-cured resin composite, Clearfil Photocore, was placed and light-cured for 40 seconds. After storage in 37 degrees C water for 24 hours, shear bond strengths were measured using a single plane shear test assembly at a crosshead speed of 2.0 mm/minute. Morphological changes of the conditioned dentin and hybrid layer formation were observed by SEM., Results: For Single Bond, the bond strengths to superficial dentin were within anticipated bounds (23 MPa), whereas the bond strengths to deep dentin (15 MPa) and floor of pulp chamber dentin (13 MPa) were significantly lower (P < 0.05). For Clearfil Liner Bond 2V, higher bond strengths (approximately 30 MPa) were obtained for each region. The data were analyzed by one- and two-way ANOVA, and Fisher's PLSD (P < 0.05). The appearance of the conditioned dentin varied according to dentin region and conditioner. For Single Bond, thick hybrid layers (3-4 microm) were observed, while thin hybrid layers (less than 0.5 microm) were observed in Clearfil Liner Bond 2V for all regions.

Purpose: To evaluate clinically whether the addition of glutardialdehyde to the one-bottle enamel-dentin adhesive Gluma Comfort Bond (GCB) has a desensitizing function, as insinuated by the brand name Gluma Comfort Bond+Desensitizer (GCB+D)., Materials and Methods: Two pain studies following identical protocols were conducted in Abu Dhabi (A) and Bologna (B). Each of the 60 and 59 patients selected, respectively, had two sensitive cervical tooth sites, characterized by a score three or higher on a five-step pain scale: 1 (no), 2 (slight), 3 (mild), 4 (severe), 5 (very severe) discomfort upon application of a 2-second cold air stimulus. The buccal sensitive sites treated in A were generally small, in B larger and in most cases extending into the proximal tooth area. The patients indicated their discomfort level according to the pain scale prior to and immediately after topical application of GCB and GCB+D, respectively, and then at recalls after 1 week, 1 (A) or 3 (B) months, and 6 months. The data was statistically analyzed by chi2-tests (P < 0.05)., Results: With the cumulative scores 1 and 2, the following percentage success rates were found for GCB/GCB+D. A: postoperatively 93/98, 1 week and 1 month 98/98, and at 6 months 92/100. In B, the respective decrease in sensitivity was uniformly 43/100 throughout the entire evaluation period, postoperatively through 6 months. The 33 teeth (57%) of GCB with scores 3 and 4 in the B-study received a rescue treatment with Gluma Desensitizer immediately after the 1 week recall. This regimen reduced the sensitivity instantaneously to scores 1 and 2 until the end of the evaluation after 6 months. In the A-study, GCB+D was significantly more effective than GCB after 1 week, 1 month, and 6 months, in the B-study at all recall sessions. It is hypothesized that a thin film of adhesive applied to a sensitive area may not polymerize and seal the dentin surface adequately due to oxygen inhibition. In particular, proximal sensitive tooth sites with poor access for adhesive application are suspected to remain inadequately sealed with a polymer film and thus sensitive. In this latter case however, glutardialdehyde as a component of the adhesive compound will result in coagulation of peripheral tubular liquid protein and thus desensitization, due to hampering of the liquid shift across the tubules upon excitation of a cold stimulus. In conclusion, glutardialdehyde played an active and effective role as a desensitizing agent, when added to the ethanol-water based one-bottle adhesive Gluma Comfort Bond.

Purpose: To measure bond strengths of three commercial compomers using recent dentin bonding systems, and to observe the micromorphology of the cross-sectional interface of the bonded specimens., Materials and Methods: One hundred and ten bovine teeth stored frozen were used. The dentin surfaces were ground flat with #600-grit silicon carbide paper, and divided into three groups for bonding: original bonding system group (Xeno Bond/Xeno, Prime&Bond 2.1/Dyract AP, and F2000 Primer/Adhesive/F2000 compomer), Clearfil Liner Bond 2V group (LB 2V/Xeno, LB2V/Dyract AP, LB2V/F2000 compomer, LB2V/AP-X), and Single Bond group (SB/Xeno, SB/Dyract AP, F2000 compomer, SB/Z100). After the bonding procedures had been performed, the bonded assemblies were stored in water for 24 hours at 37 degrees C. Then, tensile bond strengths were measured using a universal testing machine at a crosshead speed of 2 mm/minute. All data were statistically analyzed using one-way ANOVA and Fisher's PLSD at 95% of confidence. Specimens for SEM observations were bonded in the same manner as for the tensile bond test, cut in half, and embedded in epoxy resin. These were then polished to high gloss, gold sputter-coated, and observed with the SEM., Results: Compomers bonded to dentin with recent dentin bonding systems showed significantly higher bond strengths than those with the original bonding systems (P< 0.05). Tensile bond strength of Clearfil Liner Bond 2V was also significantly higher than that of Single Bond (P< 0.05). SEM observations showed good interaction between the compomers, adhesive systems, and dentin with any restorative material used. For Xeno Bond/Xeno, Prime & Bond 2.1/Dyract AP, and Primer/Adhesive/F2000 compomer, the thicknesses of the hybrid layer were approximately 0.8-1.1 microm, 0.3-0.5 microm, and 0.7-1.5 microm respectively. On the other hand, the hybrid layer produced by LB2V was approximately 0.5 to 1.0 microm, whereas for SB was approximately 3.1 to 4.1 microm thick. The thickness of the hybrid layers created in each bonded sample depended on the adhesive material used.

Purpose: Recently, several 'one-bottle' systems have been introduced for bonding into root canals. This study evaluated the influence of two brushes used as carriers of a primer-adhesive solution in the formation of resin tags, adhesive lateral branches and hybrid layer when used to bond fiber posts., Materials and Methods: Twenty root canal treated teeth, extracted for periodontal reasons, were selected for this study. The samples were randomly divided into two groups of 10 samples each: Group 1: Microbrush + One Step + Dual Link resin cement; Group 2: One Step + Dual Link resin cement. The adhesive system and resin cement were used strictly following manufacturers' instructions. The priming-adhesive solution of the 'one-bottle' system was light-cured before placing the resin cement and the post. Twenty translucent fiber posts were used. Then, root samples were processed for SEM observation., Results: The adhesive system showed resin dentin interdiffusion zone (RDIZ), resin tag and adhesive lateral branch formation. Microscopic examination of restored interfaces of Group 1 showed a higher % (P < 0.05) of RDIZ than those found in samples of Group 2. In Group 2 samples RDIZ morphology was well detectable and uniform in the first two thirds of root canals while in the apical third the RDIZ was not uniformly present while in Group 1 RDIZ was visible at the apical third too. No statistically significant differences were found among the two groups coronally and at the middle third, while the apical third of Group 1 showed significantly more resin tags than in Group 2. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals of both groups and at the apical third of Group 1. In the apical third of Group 2 root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other observed thirds.

Purpose: To measure the inward flux of potassium across human dentin disks, in vitro, in the absence and then in the presence of a simulated pulpal pressure (PP), before and after brushing with two desensitizing dentifrices., Materials and Methods: Dentin discs were made from extracted unerupted third molars and etched with 6% citric acid to remove the smear layers. The hydraulic conductance (Lp or outward fluid movement) of the discs was measured before and after brushing for 2 minutes with two desensitizing dentifrices, Colgate Sensitive Maximum Strength or Sensodyne Fresh Mint, both dentifrices containing 5% potassium nitrate. The potassium flux was measured at a pressure of 0 cm H2O, and a simulated pulpal pressure of 20 cm H2O., Results: The results showed the Colgate-brushed specimens had lower Lp (P < 0.05) than specimens brushed with Sensodyne or with saline. The Colgate-brushed specimens had a corresponding lower K+ flux, at a PP = 0 cm H2O, than specimens brushed with saline, but were not significantly different than specimens brushed with Sensodyne dentifrice. However, when the pressure was increased from 0 to 20 cm H2O, to simulate outward dentin fluid pressure, there were significant decreases in K+ flux across all three treatment groups, but the K+ flux of the Colgate-brushed specimens were affected the least, resulting in the Colgate-brushed specimens having significantly (P < 0.05) greater K+ fluxes than the saline or Sensodyne dentifrice-brushed groups. The magnitude of reduction in K+ flux in going from 0 cm H2O to 20 cm H2O was demonstrated to be linearly related to the magnitude of the Lp of the brushed specimens. Hence, a small Lp corresponded to a small reduction in K+ flux, and a correspondingly large K+ flux at 20 cm H2O. An explanation of this phenomenon is that a decrease in the Lp of dentin, produced by brushing, corresponds to a decreased outward dentin fluid flow. This lowers the outward K+ convective flow and also lowers the inward K+ diffusion. However, since the decrease of the outward K+ convective flow is greater than the decrease of the inward K+ diffusion, and the net flux is the algebraic sum of these two terms, the result is greater net inward K+ flux through the dentin. Therefore, the Colgate-brushed specimens, which exhibited the lowest Lp, provided the greatest inward K+ flux at simulated dentin fluid pressure.

Purpose: To evaluate the interface with tooth structure, mode of failure and stability of Fuji Bond LC (FBLC) resin-modified glass-ionomer bonding system., Materials and Methods: The study was in three main parts. The first part with interfacial characteristics of FBLC. The micropermeability of the FBLC/dentin interface of restored cavities in extracted teeth, after fluorescent dye was introduced into the pulp chamber, was assessed by confocal microscopy. In other teeth, confocal microscopy was also used to examine trhe failure of FBLC bonded to flat dentin surfaces, on shear loading. In the second part, cervical cavities restored with FBLC (with and without light-curing) and a resin-based composite were examined for stability of the interface over the first 15 minutes. In the last part of the study, a new fluorescent dye was mixed with FBLC for restoration of cavities and subsequent examination using 2-photon imaging techniques., Results: FBLC adapted well to tooth structure, had an interface with dentin that was permeable to fluid and displayed the absorption layer. Shear loading at the dentin interface resulted in complex failure with areas of cohesive failure where the absorption layer was present. Light-curing of FBLC seemed to produce a stable restorative while "co-curing" resulted in an unstable situation, with the appearance of an emmisable exudate from the FBLC. Advanced fluorescent imaging of the material itself seemed to suggest that there was a movement of aluminum ions in a manner similar to other glass-ionomer cements. The presence of HEMA in the matrix of the cement associated with the absorption layer was also demonstrated.

Purpose: To characterize resin-dentin bond structures of three adhesive resin systems using fractographic analysis to measure the area of failure at the fractured surface., Materials and Methods: Flat dentin surfaces were ground perpendicular to the long axis of the tooth. The prepared dentin surfaces were treated by one of three adhesive resin systems (Mac Bond II, One-Step, and Single Bond). The samples were sectioned perpendicular to the adhesive interface to produce a square bar-shaped specimen (adhesive area: 0.9 mm2) using a diamond saw. A micro-tensile test was then conducted at a crosshead speed of 1.0 mm/min. The mean tensile bond strengths were statistically compared using one-way ANOVA and Fisher's PLSD test (P< 0.05). The fractured surfaces of all specimens were examined using SEM and the area of failure was measured using an image analyzer on SEM microphotographs., Results: No significant differences in tensile bond strength were observed between Single Bond (62.1+/-18.2 MPa) and One-Step (53.8+/-13.1 MPa) (P > 0.05). However, the bond strength of Mac Bond II (36.5+/-13.7 MPa) was significantly lower than that of One-Step or Single Bond (P< 0.05). At the fractured surface, except for the cohesive failure of the bonding resin and resin-based composite, different failure patterns were observed for each resin system as follows: the failure of the hybrid layer and demineralized dentin was observed in the two wet bonding systems (One-Step and Single Bond) and of the hybrid layer but not the demineralized dentin in the self-etching primer system (Mac Bond II). The results demonstrated that the integrity of the hybrid layer depends on the adhesive system.

Purpose: To evaluate in vitro the influence of different clinical conditions (temperature, relative humidity) on dentin bond strength., Materials and Methods: Two different bonding systems were studied, ScotchBond Multi-Purpose Plus (SBMP) and Clearfil SE Bond (SE Bond). In the first part of the study, the different environmental conditions were: ambient conditions, i.e. 20 degrees C/30% relative humidity (RH), 30 degrees C/50% RH, 30 degrees C/65% RH, 33 degrees C/80% RH and 35 degrees C/95% RH. In the second part, the different interfaces (dentin/primer, primer/adhesive and adhesive/composite for SBMP and primer/adhesive, adhesive/composite for SE Bond) were also studied in order to explain the results obtained in the first part of the study. After the bonding procedure, a composite cylinder (Z100) was bonded to the surface using a Teflon mold (diameter: 3 mm/height: 5 mm). The different specimens were tested in a shear bond mode after a 24-hour storage in distilled water at 37 degrees C., Results: For SBMP, the shear bond strengths decreased when temperature/RH increased. The average values were very low when the 35 degrees C/95% RH conditions were simulated. A study of the interfaces showed that the primer/adhesive interface was the most sensitive to the environmental conditions simulated. For SE Bond, a decrease occurred but only at the highest temperature/humidity conditions. The interface study did not provide an explanation of the results obtained in the first part of the study.

The term "nanoleakage" was introduced to describe a specific type of leakage within the dentin margins of restorations. Nanoleakage appears as a consequence of the acid etching procedure allowing the penetration of oral and pulpal liquids such as acids into porosities within or adjacent to the hybrid layer. Nanoleakage is independent from microleakage. The amount of penetration depends on the type of bonding agent and on different parameters of the application technique (e.g. etching time, dentin moisture). Nanoleakage is much less extensive than microleakage and has probably no short-term clinical relevance. The long-term stability of the adhesive bond between dentin and restorative material, however, might be adversely affected. Nevertheless, based on the knowledge to date, acid etching prior to dentin bonding should be performed.

Purpose: To characterize with scanning electron microscopy (SEM), the morphology of adhesive interfaces that had been functioning in an oral cavity for several years., Materials and Methods: Cavities were prepared in vivo in caries-affected primary molars under local anesthesia. After removal of the entire carious lesion, the cavity was restored with a dentin adhesive system (Scotchbond Multi-Purpose). After several yrs, as the successor permanent teeth erupted, the resin-filled teeth were extracted. Then, the extracted resin-restored primary molars were cross-sectioned perpendicular to the adhesive interface using a low speed diamond saw and then polished for SEM examination., Results: Morphological changes, such as digestion of the collagen fibrils and deterioration of the bonding resin and hybrid layer, were observed at the interface of the oral environment specimens. The results of this study demonstrated that degradation of resin-dentin bond structures appeared to occur in the human oral environment over time.

Purpose: To evaluate the bond strength of two dentin-bonding systems to root canal dentin., Materials and Methods: Six central incisors, extracted for periodontal reasons, were endodontically treated, no obturation of the root canal space was performed. The teeth were cut parallel to their long axis. One half of each tooth was randomly assigned to one of two experimental groups. The teeth of the first group were treated with All-Bond 2 dental adhesive and those of the second group with Panavia F. The root canal dentin was conditioned as suggested by the manufacturers and, after the application of the dental adhesives, a layer of resin-based composite was polymerized over the adhesive layer. After the composite had completely set, the sections were prepared for microtensile test and kept in a wet environment at a relative humidity of 90 +/- 2% measured with a digital relative humidity meter and at a temperature of 22 degrees C for 24 hrs. The specimens were sectioned perpendicularly to the bonded interface, into slabs 1.5 mm thick (10 sections for each experimental group). The slabs were then trimmed by super fine diamond burs for the microtensile bond test with the narrowest region located at the respective bonded interface. The thickness of the slab was then exactly established by three measurements performed in three points of each slab by a digital micrometer. The specimens were then subjected to a tensile force at a crosshead speed of 0.2 mm/min. The test was observed using a confocal microscope and the failure modes were noted. The load at failure was registered and the bonded area was measured using a confocal microscope at a magnification of x25 in conjunction with an image-processing program. The failure data were analyzed using the Wilcoxon-Gehan test with exact non-parametric inference., Results: The mean value at failure was the same for the two experimental groups (17.1 MPa). There was no statistically significant difference between Panavia F and All-Bond 2 (P> 0.8671). Most of the specimens showed a debonding of the adhesive from the hybrid layer. The results showed that the bond strength of the two bonding systems tested to the dentin of the root canal are slightly lower than to those obtained with the latest adhesive systems, in the coronal dentin.

Purpose: To evaluate, in vivo, the formation of hybrid layer, resin tags and adhesive lateral branches, by an experimental dual-curing "one-bottle" enamel-dentin bonding system., Materials and Methods: The new dentin adhesive (Excite DSC) was tested in five Class V restorations placed in vital, periodontally compromised teeth. The experimental bonding system was used in combination with a flowable composite. After 1 wk the teeth were extracted and processed for SEM evaluation. All the samples were split-fractured along their long axis. Half of the samples were used to evaluate hybrid layer formation and the other half to examine the morphology of resin tags., Results: The experimental adhesive system showed a micromechanical bonding mechanism to conditioned dentin with formation of a hybrid layer, resin tags and adhesive lateral branches. SEM photomicrographs of the decalcified samples showed a high density of resin tags and uniform distribution along the cavity walls.

Purpose: To test if there was a correlation between resin-dentin bond strengths and nanoleakage of total etch and self-etching primer bonding systems., Materials and Methods: Ten extracted third molars were ground flat with 600 grit SIC paper under running water to expose middle dentin. Clearfil Liner Bond 2V or Single Bond was applied to the dentin surface according to the manufacturers' instructions. A crown was built-up with Clearfil AP-X resin-based composite, and the specimens stored in water for 24 hrs at 37 degrees C. The bonded assemblies were cut mesiodistally perpendicular to the interface into approximately 0.7 mm thick slabs, and trimmed for microtensile bond strength testing. Alternate slices from each tooth were either entirely double-coated with nail varnish leaving a 0.5 mm window around the interface, or left uncoated to be immersed in water for 13 hrs as the control. The varnished (experimental) slabs were immersed in 50% AgNO3 for 1 hr, and then immersed in a photo developing solution for 12 hrs. All specimens were subjected to microtensile bond test at a crosshead speed of 1 mm/min. After debonding, the specimens were embedded in epoxy resin and observed under a confocal laser scanning microscope for determination of lateral silver penetration within the interface. Silver penetration was further analyzed under the SEM. Data were analyzed with one- and two-way ANOVA, Fisher's PLSD test (P < 0.05), and regression analysis., Results: The bond strengths of Clearfil Liner Bond 2V and Single Bond were not significantly different (P > 0.05); however the bond strengths of the specimens that were soaked in 50% AgNO3 for 1 hr significantly increased (P < 0.01). No correlation was observed between bond strengths and nanoleakage.

Purpose: To evaluate the effectiveness of a one-bottle adhesive system as a desensitizing treatment, with or without a prior phosphoric acid-etch step., Materials and Methods: Two different clinical procedures using a one-bottle adhesive bonding system were tested for its efficacy on desensitizing exposed roots. Thirty subjects with a history of dentin hypersensitivity were selected and 60 exposed sensitive teeth were divided into two groups (n = 30). In Group 1 samples, Scotchbond 1 bonding system (Single Bond in USA) was applied without a prior acid-etching, while in those of Group 2, the exposed sensitive roots were acid-etched with 35% phosphoric acid for 15 seconds, prior to application of bonding agents. The sensitivity was evaluated at 0, 1, 2, 4 weeks and 3 months using cold air blast stimuli, and recorded using a visual-analogue scale. The scores were analyzed as non-parametric data by means of the Mann-Whitney and Sign tests. Five samples from each group were randomly selected in order to make scanning electron microscope observations of the sensitive dentin surfaces at baseline and at each recall using the replica technique., Results: At baseline, after both desensitizing procedures all the patients reported distinct reductions in dentin sensitivity. At 1- and 2-week recalls, 20 teeth of Group 1 and 17 teeth in Group 2 exhibited a return of sensitivity, and in five teeth in each group, the sensitivity score was between 5-8. During the first recall (1-2 weeks), the sensitive teeth were retreated and showed an immediate reduction of sensitivity. At the 1-month recall, eight teeth in Group 1 and four teeth in Group 2 showed a return of some sensitivity, and in six teeth in Group 1 and in three teeth in Group 2, old amalgam restorations were replaced and this procedure almost completely resolved the sensitivity. At the 3-month recall, only five teeth from each group showed residual mild sensitivity (score 1-2). For both Groups 1 and 2 there was a statistically significant (P < 0.0005) reduction in sensitivity levels between the baseline pain scores and immediately after treatment, and between the first recall pre-treatment pain scores and the last recall pain scores. Overall, the two methods of treatment demonstrated a general decrease in sensitivity in both groups over the 3-month study period, adequately solving the clinical and patients' perception of the discomfort of sensitivity. The SEM observations of the replicas showed a progressive loss of the adhesive resin from the treated surfaces. This fact was more evident in the non-etched samples (Group 2) than in those in Group 1. The results of this study showed that exposed root dentin sealed with Scotchbond 1, with or without prior acid-etching, did not show spontaneous sensitivity after 3 months.

Purpose: To examine and compare the effect of saliva contamination on the resin micromorphologic adaptation of four single-bottle adhesives., Materials and Methods: Prime & Bond 2.1, One-Step, Tenure Quik with fluoride and Syntac Single Component adhesives were evaluated. Sixty sound molars were divided into three subgroups for each of the four adhesives; Class V cavities were prepared with gingival margins at cementum. Each adhesive was tested under: Normal conditions (Group 1), contamination of the cavity with fresh whole saliva for 20 seconds and removing the excess (Group 2), and contamination of the cavity with fresh whole saliva for 20 seconds and rinsing the saliva for 20 seconds before adhesive application (Group 3). After curing the adhesive, the cavities were filled with Z100 composite, fixed in 2.0% glutaraldehyde and sectioned into two halves. The sectioned halves were fixed again and rinsed with 0.2 M sodium cacodylate buffer. The cut surfaces were wet ground, polished and sonicated in distilled water. The specimens were immersed in decalcifying solution, deprotenized, serially dehydrated, mounted on aluminum stubs, sputter coated and examined under the SEM., Results: The four adhesives formed hybrid layer with resin tags penetration into the dentin. P & B 2.1 showed usually funnel-shaped resin tags; One-Step, cylindrical shape; Tenure Quick and Syntac SC, variable shapes. Saliva contamination did not prevent hybrid layer formation or resin penetration into the dentin tubules. Only Syntac SC displayed a relatively thin hybrid layer with the unwashed saliva-contaminated group.

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.

Purpose: To evaluate the influence of surface treatment with 20% polyacrylic acid containing 3% aluminum chloride (AlCl3) on the shear bond strength of an improved resin-modified glass ionomer cement to enamel and dentin, and to analyze the micromorphology of the cement-tooth interface., Materials and Methods: Flat enamel and dentin surfaces of bovine incisors were ground up with sequentially finer abrasives to 1000-grit silicon carbide paper. Each surface was treated with 10% polyacrylic acid (Dentin Conditioner: DC) for 20 seconds or with 20% polyacrylic acid containing 3% aluminum chloride (Cavity Conditioner: CC) for 10 seconds, rinsed, and gently air-dried. A resin-modified glass ionomer cement (Fuji II LC) and its improved version (Fuji II LC-I) were applied to the tooth substrate, and bond strengths measured at periods of 5 minutes, 1 day, and 1 week after light curing. As a control, the resin-modified glass ionomer cements were applied to untreated surfaces and were tested at 1 day. To evaluate the interface micromorphology, specimens were prepared following the adhesive-sandwich technique, cut in equal halves, and observed under a scanning electron microscope (SEM). Additionally, in order to observe the effect of surface pre-treatment of each conditioner on dentin, pre-treated dentin disks were freeze-dried, fractured, and the morphology of the treated and fractured surfaces were observed., Results: Shear bond strength of CC+ Fuji II LC-I to enamel was significantly higher than that of DC+ Fuji II LC at 1 day and 1 week (P < 0.0001). As for dentin, the improved system showed significantly higher bond strength at 5 minutes after light curing (P < 0.001), but bond strengths were not statistically different at 1 day and 1 week. Fracture patterns, examined with a stereomicroscope, were mixed adhesive/cohesive within the cement for all groups. Interface micromorphology, observed with an SEM, suggested the formation of a resin-rich layer and an indistinct zone between the resin-modified glass ionomer cements and the underlying dentin.

Purpose: This study investigated the effect of reversible and irreversible rewetting on the application of One-Step, single-bottle, water-free, acetone-based primer/adhesive., Materials and Methods: Thirty 1 mm dentin discs prepared from third molars were each conditioned with 10% H3PO4 for 20 seconds and rinsed for 20 seconds. They were randomly divided into five groups: Group 1 (positive control): conditioned dentin bonded visibly moist; Group 2: bonded after drying for 3 seconds; Group 3: drying for 3 seconds and rewetting with distilled water; Group 4 (negative control): drying for 3 seconds, stored in 8% glutaraldehyde for 15 minutes, rinsed with distilled water and dried for 3 seconds; and Group 5: drying for 3 seconds, stored in glutaraldehyde for 15 minutes, rinsed with distilled water and bonded visibly moist. One-Step was applied in two coats according to the manufacturer's recommendation and discs in each group were further bonded together to form a disc-pair using a chemical cure resin, demineralized in EDTA and prepared for TEM examination., Results: Complete resin infiltration into the zone of demineralized dentin was observed in Group 1 and 3. In Group 2, resin infiltration was limited to the surface and base of the demineralized network apparently along the lateral branches of the dentin tubules. A middle zone of suboptimal infiltration was observed. In Group 4 and 5, minimal resin infiltration was only observed along the base of the demineralized network upon their fixation in a collapsed state with glutaraldehyde.

Purpose: To evaluate in vivo and in vitro the formation of hybrid layer, resin tags and adhesive lateral branches, by use of three different enamel dentin bonding systems., Materials and Methods: The dentin adhesives were tested on flat dentin preparations made on buccal surfaces of vital, periodontally compromised teeth. The samples were randomly divided in four groups: Group 1: Prime & Bond 2.0; Group 2: Scotchbond Multi-Purpose Plus; Group 3: Clearfil Liner Bond 2 (the self-etching primer was applied for 30 seconds on the enamel and dentin); Group 4: Clearfil Liner Bond 2 (the self-etching primer was applied for 60 seconds on the enamel and dentin). The sample teeth were extracted immediately after the bonding was cured. The same procedure described for the in vivo samples was performed in vitro on extracted molars. All the samples were split-fractured along their long axis. Half of the samples were used to visualize the hybrid layer and the other half to observe the morphology of resin tags by use of scanning electron microscopy., Results: All the tested products formed a hybrid layer, both in vivo and in vitro. In many areas of the samples of Groups 1, 2 and 4, characteristic reverse cone-shaped tags with their corresponding adhesive lateral branches were evident. In contrast to this, resin tags found in samples of Group 3 were narrower at the tubule orifices, and adhesive lateral branches were scarce. The length of the resin tags observed in the samples of Groups 1 and 2 were longer than those found in Groups 3 and 4. The morphology of the hybrid layer of the in vivo samples was similar to that of the in vitro samples.

Purpose: To investigate the interaction of six experimental and commercial bonding systems with dentin in vivo., Materials and Methods: One-Step, Clearfil Liner Bond 2, OptiBond, Permagen with 10% phosphoric acid, Permagen with 35% phosphoric acid, and Prime & Bond were applied in standard Class I occlusal cavities in premolars scheduled for extraction for orthodontic reasons, combined either with a self-cured or with a light-cured resin composite. The teeth were carefully extracted 5 minutes after resin polymerization and fixed in 2.5% glutaraldehyde. After fixation, the specimens were dehydrated, sectioned, and processed for field-emission SEM., Results: Although some systems produced gap-free intact interfaces in specific specimens, all of them showed detachment at the transition between the resin-dentin interdiffusion zone and the fluid resin placed over it. It was apparent that the presence of air-bubbles and/or thick layers of polymerized-filled fluid resin resulted in less frequent separation areas at the resin-dentin interface, providing support for the concept of the elastic cavity wall. It was also confirmed that some dentin adhesive systems do not form a thick layer over the dentin, otherwise the resin composite would not have penetrated the dentin tubules.

Purpose: To identify ultrastructural features resulting from possible primer-water interaction when a two-bottle, acetone- and alcohol-based dentin adhesive (All-Bond 2) was applied to acid-conditioned dentin in the presence of excess water., Materials and Methods: Three groups (3-second dry, visibly moist, overwet), each comprising eight dentin discs prepared from human third molars, were established and bonded with All-Bond 2 under different degrees of surface moisture. Variations in the ultrastructural appearance of the resin-dentin interface from laboratory demineralized and epoxy resin embedded disc pairs were examined either with en bloc ruthenium red pre-staining alone or further stained with uranyl acetate and lead citrate., Results: Displacement of water by the volatile primer solvents resulted in the formation of a layer of resin-impregnated dentin in the three groups. Interaction of the primer with water following the evaporation of the volatile primer solvents resulted in phase separation of the primer components. Ultrastructural features observed within the previously water-filled blister-like spaces on the dentin surface in the visibly moist and overwet groups recapitulated what was observed within partially water-filled dentin tubules in the 3-second dry group. The overwet phenomenon appeared to be a result of emulsion polymerization, involving irreversible interaction of water-soluble bifunctional primer components with those that are water-immiscible, through the formation of micelles, resulting in the absence of total interfacial integrity.

Purpose: To study with the scanning electron microscope the interfacial phenomenon that occurred in the presence of excessive surface moisture following the application of an acetone-based adhesive to acid-conditioned dentin., Materials and Methods: Specimens consisted of flat dentin discs that were divided into three groups based upon the status of remaining surface moisture: (1) 3-second dry group, (2) blot-dry group, with the conditioned dentin surface remaining shiny as opposed to matte, and (3) overwet group: an additional 40 mL of distilled water spread thin on the dentin surface after blot-drying. Polished resin-dentin interfaces were brought into relief using plasma-etching and examined without further embedding., Results: Although a hybrid layer was observed in all three groups, there was (1) a sequential deterioration of the bonded assembly along the hybrid layer-resin interface, and (2) loss of complete tubular seal as the quantity of surface moisture increased. Intratubular resin globules were observed beneath short resin plugs in the 3-second dry group. Small, isolated blister-like spaces, trapped within the resin layer, were observed along the surface of the hybrid layer in the blot-dry group, while similar, but larger spaces were found in the overwet group. The blister-like spaces, which were often continuous with incompletely sealed tubular orifices, were partially filled with extraneous resin globules dispersed within an amorphous matrix.

Purpose: To evaluate the interfacial morphology (SEM) of two bonding systems to superficial and deep dentin using a reverse-sandwich technique, coupled with measurement of micro-tensile bond strengths (MTBS). MATERIALS AND METHODDS: Superficial and deep dentin disks were prepared from the same tooth in freshly-extracted human third molars. All-Bond 2 (total etch versus no etch) or Imperva Bond (total etch versus no etch) were applied to superficial versus deep dentin surfaces and the two disks were bonded together into a reverse-sandwich configuration., Results: SEM revealed that All-Bond 2 and Imperva Bond applied under total etch conditions formed thicker resin-infiltrated layers (4-8 micrometers) on deep dentin than on superficial dentin (2-4 micrometers), and that All-Bond 2 and Imperva Bond applied to unetched dentin formed very thin resin-infiltrated layers (less than 0.5 micrometers) on both dentin substrates. MTBS of All-Bond 2 and Imperva Bond were more than 20 MPa irrespective of dentin depth and were not significantly different. Without acid etching, the MTBS of both systems to deep dentin was significantly lower than to superficial dentin. These results suggested that for the total-etch systems, dentin depth affected the thickness of the resin-infiltrated layer, but the thickness of the resin-infiltrated layer had no significant relationship with MBTS. The present data also indicated that the acid-etch technique could prevent the decrease of bond strength seen in deep dentin in the absence of etching.

Purpose: This study investigated the hypothesis that the new resin-reinforced, light-cured ionomer cement (GIC) can develop mechanical retention by forming a hybrid layer in acid-etched dentin., Materials and Methods: Dentin discs were obtained from extracted human third molars and sanded with 320 SiC abrasive paper. One third of the surface was acid etched with 10% maleic acid for 15 seconds, washed and gently air-dried for 5 seconds. ProBond primer from the VariGlass (VG) GIC kit was applied onto the acid-etched surface (A) and another third of the unetched surface (B) for 30 seconds. One third of the surface was not treated (C). VG GIC was then applied onto the ++entire surface of the disc. After 24 hours the discs were fractured along their diameters. One half of the fractured disc was highly polished at the interface and treated with 6N HCl for 30 seconds while the other half of the fractured specimen was left untreated. Both halves were viewed by SEM. In another part of the study, a micro-tensile bond strength (MTBS) test was carried out to compare the acid-etched group vs. the nonetched group., Results: SEM pictures revealed a well defined demineralized, resin-infiltrated zone approximately 3 micrometers in thickness for group (A) for both fractured and polished surface. Dentin surfaces that only received primer (B) showed an irregular zone 0.5 micrometers thick. Such a resin-infiltrated layer was resistant to HCl treatment. A gap was observed between the GIC and dentin in group (C). Polished interfaces appeared to be highly infiltrated. However, fractured interfaces revealed considerable porosity within the demineralized-infiltrated zone. MTBS results were (X +/- SD, MPa): 28.9 +/- 5.8 for the etched group and 24.5 +/- 4.9 for the nonetched group. This difference was statistically significant.