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The purpose of this study was to investigate the tissue reaction stimulated by BaSO4‐ and Bi2O3‐containing White MTA Angelus, in comparison with Bi2O3‐containing white Portland cement, and white ProRoot MTA. Thirty‐six adult male Wistar rats (Rattus norvegicus), weighing between 250 and 300 g, were distributed into three groups (n = 12) in accordance with the period of sacrifice (15, 30, and 60 days). Four polyethylene tubes filled with the tested cements were implanted into the dorsum of each rat. Lateral wall of the tubes served as the negative control. After the experimental periods, the animals were euthanized by overdose of pentobarbital anesthetic solution, and the specimens were prepared for microscopic analysis under ×50, ×100, and ×400 magnifications. Inflammatory scores (0–3) were used to grade the tissue reaction. Data were analyzed by the Kruskal‐Wallis test and Dunn's test for individual comparisons (p <.05). A mild to moderate inflammatory tissue reaction was observed at the 15‐day period, which decreased over the course of the periods for all cements, except for Portland cement. There was no significant difference among the tissue responses for ProRoot MTA, BaSO4‐ and Bi2O3‐containing White MTA Angelus at the 60‐day period (p >.05). The Portland group had moderate inflammatory reaction at the final period of analysis, which was statistically different when compared to the other groups (p <.05). The microscopic findings of this animal study suggest that the addition of BaSO4 to White MTA Angelus does not hampers the biocompatibility of the cement. [ABSTRACT FROM AUTHOR]

A water-soluble crosslinking agent, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide ( EDC), has been used as a pretreatment of acid-etched dentin to inactivate matrix-bound endogenous dentin proteases. The aim of this study was to evaluate the effect of pH on the inactivation capacity of EDC. Demineralized dentin beams (1 × 2 × 6 mm) were divided into six groups ( n = 8 per group). Then, EDC (0.3 M) was solubilized in distilled water with pH of 2, 4, 6, 7, 9, or 11. Control EDC was solubilized in 0.1 M 2-( N-morpholino) ethanesulfonic acid ( MES) buffer and its pH was adjusted to 6. The dentin beams were pretreated for 1 min with EDC at each pH or with EDC in MES buffer at pH 6.0 and then incubated in 1 ml of simulated body fluid ( pH 7.2) for 1, 3, 7, or 14 d. Untreated beams served as controls. At each study time-point, the dry mass of dentin beams was assessed and the incubation media were analyzed for carboxyterminal telopeptide of type-I collagen ( ICTP) and C-terminal telopeptide of type I collagen ( CTX) using specific ELISAs. Data were subjected to repeat-measures anova. The results of the study indicated that specimens pretreated with EDC in MES buffer showed the lowest collagen degradation in terms of mass loss and release of telopeptides, while specimens pretreated in alkaline media showed the highest collagen degradation. This study indicates that the pH of the EDC solution plays an important role in the stability of dentin protease inactivation. [ABSTRACT FROM AUTHOR]

Degradation of the hybrid layer created in dentin by dentin adhesives is caused by enzyme activities present within the dentin matrix that destroy unprotected collagen fibrils. The aim of the present study was to evaluate the effect of a one-step self-etch adhesive system on dentinal matrix metalloproteinases 2 and 4 ( MMP-2 and MMP-9, respectively) using in situ zymography and an enzymatic activity assay. The null hypothesis tested was that there are no differences in the activities of dentinal MMPs before and after treatment with a one-step adhesive system. The MMP-2 and MMP-9 activities in dentin treated with the one-step adhesive, Adper Easy Bond, were quantified using an enzymatic activity assay system. The MMP activities within the hybrid layer created by the one-step adhesive tested were also evaluated using in situ zymography. The enzymatic assay revealed an increase in MMP-2 and MMP-9 activities after treatment with adhesive. In situ zymography indicated that gelatinolytic activity is present within the hybrid layer created with the one-step self-etch adhesive. The host-derived gelatinases were localized within the hybrid layer and remained active after the bonding procedure. It is concluded that the one-step self-etch adhesive investigated activates endogenous MMP-2 and MMP-9 with the dentin matrix, which may cause collagen degradation over time. [ABSTRACT FROM AUTHOR]

Inhibition of endogenous dentin matrix metalloproteinases (MMPs) within incompletely infiltrated hybrid layers can contribute to the preservation of resin-dentin bonds. This study evaluated the bond stability of interfaces treated with benzalkonium chloride (BAC) and benzalkonium methacrylate (MBAC), and the inhibitory properties of these compounds on dentin MMP activity. Single-component adhesive ALL-BOND UNIVERSAL, modified with BAC or MBAC at concentrations of 0, 0.5, 1.0, and 2.0%, was used for microtensile bond strength ( μTBS) evaluation after 24 h, 6 months, and 1 yr. Beams produced from human dentin were treated with 37% phosphoric acid, dipped in 0.5% BAC, 1.0% BAC, or water (control) for 60 s, and then incubated in SensoLyte generic MMP substrate to determine MMP activity. A significant decrease in the μTBS after 6 months and 1 yr was observed for the control group only. No significant differences among groups were shown at 24 h. After 6 months and 1 yr, the control group demonstrated significantly lower μTBS than all treatment groups. When applied for 60 s, 0.5% BAC inhibited total MMP activity by 31%, and 1.0% BAC inhibited total MMP activity by 54%. Both BAC and MBAC contributed to the preservation of resin-dentin bonds, probably because of their inhibitory properties of endogenous dentin proteinases. [ABSTRACT FROM AUTHOR]

Reducing collagen degradation within hybrid layers may contribute to the preservation of adhesive interfaces. This study evaluated the stability of resin-dentin interfaces treated with benzalkonium chloride ( BAC)-modified adhesive blends and assessed collagen degradation in dentin matrices treated with BAC. The etch-and-rinse adhesive, Adper Single Bond Plus, modified with 0.5% and 1.0% BAC, was evaluated for microtensile bond strength (μTBS) and nanoleakage (NL) after 24 h and 1 yr. Thirty completely demineralized dentin beams from human molars were dipped for 60 s in deionized water ( DW; control), or in 0.5% or 1.0% BAC, and then incubated in simulated body fluid ( SBF). Collagen degradation was assessed by quantification of the dry mass loss and the amount of hydroxyproline ( HYP) released from hydrolyzed specimens after 1 or 4 wk. Although all groups demonstrated a significant increase in NL after 1 yr, adhesive modified with 0.5% BAC showed stable bond strength after 1 yr (9% decrease) relative to the control (44% decrease). Significantly less HYP release and dry mass loss were observed for both 0.5% and 1.0% BAC relative to the control. This in vitro study demonstrates that BAC contributes to the preservation of resin-dentin bonds for up to 1 yr by reducing collagen degradation. [ABSTRACT FROM AUTHOR]

In this paper, a process for generating collagen-yttria-stabilized amorphous zirconia hybrid scaffolds by introducing acetylacetone-inhibited zirconia precursor nanodroplets into a poly(allylamine)-coated collagen matrix is reported. This polyelectrolyte coating triggers intrafibrillar condensation of the precursors into amorphous zirconia, which is subsequently transformed into yttria-stabilized zirconia after calcination. These findings represent a new paradigm in the synthesis of non-naturally occurring collagen-based hybrid scaffolds under alcoholic mineralizing conditions. [ABSTRACT FROM AUTHOR]

This study evaluated the cytotoxicity of experimental adhesive systems (EASs) on odontoblast-like cells. Paper discs ( n = 132) were impregnated with 10 µL of each EAS-R1, R2, R3, R4, and R5 (in an ascending order of hydrophilicity), followed by photoactivation. R1 and R2 are nonsolvated hydrophobic blends, R3 represents a simplified etch-and-rinse adhesive system, and R4 and R5 represent simplified self-etch adhesive systems. Discs were immersed in Dulbecco's modified Eagle's medium for 24 h to obtain eluates applied on MDPC-23 cell cultures. No material was applied on discs used as control (R0). Cell viability [3-(4,5-dimethythiazol-2-yl)−2,5-diphenyl tetrazolium bromide assay], total protein (TP) production, alkaline phosphatase (ALP) activity, type of cell death, and degree of monomer conversion Fourier transform infrared (%DC-FTIR) were evaluated. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). Considering R0 (control) as having 100% of cell viability, R1, R2, R3, R4, and R5 reduced the metabolic activity of cells by 36.4, 3.1, 0.2, 21.5, and 65.7%, respectively, but only R1 and R5 differed from R0. Comparing with R0, lower TP production was observed for R1, R4, and R5, while ALP activity decreased for R1 and R5. Necrotic cell death was predominant for all EASs, but only R1, R4, and R5 differed from R0. Only R5 presented a different apoptotic cell death ratio from R0. R1 presented the lowest %DC (ca. 37%), whereas R4 and R5 presented the highest (ca. 56%). In conclusion, R2 and R3 were not toxic to the MDPC-23 cells, suggesting that the degree of hydrophilicity or %DC of the EASs alone were not responsible for their cytopathic effects. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 101B: 1498-1507, 2013. [ABSTRACT FROM AUTHOR]

Traditional bone regeneration strategies relied on supplementation of biomaterials constructs with stem or progenitor cells or growth factors. By contrast, cell homing strategies employ chemokines to mobilize stem or progenitor cells from host bone marrow and tissue niches to injured sites. Although silica-based biomaterials exhibit osteogenic and angiogenic potentials, they lack cell homing capability. Stromal cell-derived factor-1 (SDF-1) plays a pivotal role in mobilization and homing of stem cells to injured tissues. In this work, we demonstrated that 3-dimensional collagen scaffolds infiltrated with intrafibrillar silica are biodegradable and highly biocompatible. They exhibit improved compressive stress-strain responses and toughness over nonsilicified collagen scaffolds. They are osteoconductive and up-regulate expressions of osteogenesis- and angiogenesis-related genes more significantly than nonsilicified collagen scaffolds. In addition, these scaffolds reversibly bind SDF-1α for sustained release of this chemokine, which exhibits in vitro cell homing characteristics. When implanted subcutaneously in an in vivo mouse model, SDF-1α-loaded silicified collagen scaffolds stimulate the formation of ectopic bone and blood capillaries within the scaffold and abrogate the need for cell seeding or supplementation of osteogenic and angiogenic growth factors. Intrafibrillar-silicified collagen scaffolds with sustained SDF-1α release represent a less costly and complex alternative to contemporary cell seeding approaches and provide new therapeutic options for in situ hard tissue regeneration. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: Tracheal resection anastomoses are often under tension and can be technically challenging. New suture materials such as V-loc (barbed, knotless wound closure device) may offer advantages over conventional methods. The objective of this study is to determine if a running V-loc suture is of comparable tensile strength to conventional closure. Study Design: Laboratory based study of human cadaveric tissue. Methods: Fresh human cadaveric tracheas were dissected and incised into segments. Anastomosis of adjacent segments was then performed with either submucosal interrupted 3-0 Vicryl, or a running submucosal 3-0 V-loc suture. Anastomosed specimens were stretched to failure on an Instron force tension machine. Surgeon satisfaction was recorded by visual analog scale (VAS). Results: The tensile strength of 12 tracheal anastomoses was tested. Video documentation of V-loc suture technique and anastomosis failure was recorded. In both Vicryl (80%) and V-loc (100%) anastomoses, failure occurred at the membranous intercartilaginous region. In 20% of the Vicryl anastomoses, the suture was noted to break prior to tissue failure. Anastomoses with V-loc suture had equivalent failure force (mean, 59 N) compared to interrupted Vicryl (51 N), with P = .57. On VAS, surgeons were more satisfied with V-loc suture closure compared to interrupted Vicryl closure (paired t test, P = .003). Conclusions: Tracheal anastomosis with running v-loc suture is a feasible alternative to conventional closure with interrupted Vicryl suture. V-loc suture provided a surgical advantage by improved ease of use. [ABSTRACT FROM AUTHOR]

Adu-Arko AY, Sidhu SK, McCabe JF, Pashley DH. Effect of an Er,Cr:YSGG laser on water perfusion in human dentine. Eur J Oral Sci 2010; 118: 483–488. © 2010 Eur J Oral Sci Changes in fluid perfusion through tubules may affect the sensitivity of exposed and restored dentine. The rate of perfusion is dependent on the structure and composition of dentine, particularly at the surface. This work analyzed the effect of treatment with an Erbium, Chromium-doped: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser on dentine perfusion. Extracted molars were sectioned above the mid-coronal portion, and below the cemento–enamel junction, to create crown segments. The pulp was extirpated and the dentine treated with the Er,Cr:YSGG laser, a diamond bur or sandpaper. Each specimen was mounted, with the pulp chamber oriented upwards, on a petri-dish cover in order to permit a tube filled with water to be connected to the pulp. Movement of the water meniscus over 24 h provided a measurement of the volume of water that filtered across the dentine. The dishes contained water to provide a moist environment in the relevant specimens, or were left dry to provide dry conditions. Specimens were perfused for 24 h with water pressures ranging from 20 to 60 cm. The results (in μl mm−2 d−1) showed a significant difference in the perfusion rate between treatments. The difference between perfusion in wet and dry conditions was highly significant. Laser and bur treatment of dentine significantly affected perfusion, which was higher in the former than in the latter. Therefore, laser-treated dentine may be more sensitive than bur-cut dentine. [ABSTRACT FROM AUTHOR]

Ricci HA, Sanabe ME, de Souza Costa CA, Pashley DH, Hebling J. Chlorhexidine increases the longevity of in vivo resin–dentin bonds. Eur J Oral Sci 2010; 118: 411–416. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The aim of this study was to evaluate the mechanical stability of resin–dentin bonds produced in vivo in the presence of chlorhexidine. Children presenting at least one pair of contralateral primary molars with occlusal carious lesions were enrolled in the study. After cavity preparation and phosphoric acid etching, dentin was treated with 5 μl of either 2% chlorhexidine (control group) or deionized water (experimental group). Thirteen pairs of teeth were restored and were collected after physiological exfoliation. The periods in oral function after restoration were divided as follows: up to 30 d; and 1–5, 10–12, and 18–20 months. Beam-shaped specimens (0.81 mm2) were obtained and subjected to microtensile bond-strength testing. A significant decrease of the bond strength was observed in the control group starting at the 1–5 month period (30.6%), while in the experimental group this decrease started only after 10–12 months of function (26.3%). The use of chlorhexidine as an adjuvant to the adhesion to dentin did not produce any detrimental effect to the immediate bond strength and was capable of reducing the rate of resin–dentin bond degradation within the first few months after restoration. [ABSTRACT FROM AUTHOR]

Part I was an overview of the role and function of proteoglycans and glycoproteins in the pulpo-dentin complex; part II will focus on enzymes, serum proteins, and growth factors. This review will discuss current knowledge regarding matrix metalloproteinases ( MMPs), cathepsins, serum proteins, and growth factors in dentin and the related dentin-pulp complex in an attempt to better understand their nature, role, and function in the dentin extracellular matrix ( ECM) environment. Dentin formation in physiological and pathological conditions has been widely studied. However, the regulation and involvement of non-collageneous enzymes, serum proteins, and growth factors are still not completely elucidated. MMPs, a family of 23 endopeptidases in humans, are collectively capable of degrading virtually all ECM components, and their specific tissue inhibitors ( TIMPs: tissue inhibitors of matrix metalloproteinases) participate in organo- and morphogenesis, physiological tissue turnover, and pathological tissue destruction. Similarly, the lysosomal cysteine proteinases (cathepsins) are capable of degrading ECM proteins such as collagen, laminin, fibronectin, and proteoglycans. These enzymes are implicated in a variety of pathological conditions, especially in diseases involving tissue re-modeling states. Dentin also contains serum-derived proteins (such as albumin, immunoglobulins, and transferrin), and a variety of growth factors in the mineralized ECM are available for release during demineralization or other injury. A detailed description of the components of the above-mentioned dentin non-collageneous proteins will be summarized in this literature review. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) bound to dentin matrices are activated during adhesive bonding procedures and are thought to contribute to the progressive degradation of resin‐dentin bonds over time. The purpose of this study was to evaluate the changes in mechanical, biochemical, and structural properties of demineralized dentin treated with or without chlorhexidine (CHX), a known MMP‐inhibitor. After demineralizing dentin beams in EDTA or phosphoric acid (PA), the baseline modulus of elasticity (E) of each beam was measured by three‐point flexure. Specimens were pretreated with water (control) or with 2% CHX (experimental) and then incubated in artificial saliva (AS) at 37°C for 4 weeks. The E of each specimen was remeasured weekly and, the media was analyzed for solubilized dentin collagen at first and fourth week of incubation. Some specimens were processed for electron microscopy (TEM) immediately after demineralization and after 4 weeks of incubation. In EDTA and PA‐demineralized specimens, the E of the control specimens fell (p < 0.05) after incubation in AS, whereas there were no changes in E of the CHX‐pretreated specimens over time. More collagen was solubilized from PA‐demineralized controls (p < 0.05) than from EDTA‐demineralized matrices after 1 or 4 weeks. Less collagen (p < 0.05) was solubilized from CHX‐pretreated specimens demineralized in EDTA compared with PA. TEM examination of control beams revealed that prolonged demineralization of dentin in 10% PA (12 h) did not denature the collagen fibrils. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

This study evaluated the micropermeability of six etch‐and‐rinse adhesives bonded to dentin. There were two principal groups: wet bonding with water or wet bonding with absolute ethyl alcohol. After bonding and the creation of composite build‐ups, the pulp chambers were filled with 0.1% lucifer yellow. The contents of the pulp chamber were kept under 20 cm H2O pressure to simulate pulpal pressure for 3 h. The specimens were vertically sectioned into multiple 0.5‐mm thick slabs that were polished and then examined using a two‐photon confocal laser scanning microscope (TPCLSM). The results showed that specimens bonded with adhesives using the water wet‐bonding condition all showed tracer taken up uniformly by the hybrid layer. This uptake of fluorescent tracer into the hybrid layer was quantified by computer software. The most hydrophobic experimental resins showed the highest fluorescent tracer uptake (ca. 1800 ± 160 arbitrary fluorescent units/std. surface area). The most hydrophilic experimental resins showed the lowest tracer uptake into water‐saturated hybrid layers. When ethanol wet‐bonding was used, significantly less fluorescent tracer was seen in hybrid layers. The most hydrophilic experimental resins and Single Bond Plus showed little micropermeability. Clearly, ethanol wet‐bonding seals dentin significantly better than water‐wet dentin regardless of the adhesive in etch‐and‐rinse systems. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

Dentin is the most voluminous structural component of human tooth. Dentin protects pulp tissue from microbial and other noxious stimuli. It also provides essential support to enamel and enables highly mineralized and thus fragile enamel to withstand occlusal and masticatory forces without fracturing. Furthermore, it is the first vital tissue to meet external irritation, and instead of being merely a passive mechanical barrier, dentin may in many ways participate in dentin-pulp complex defensive reactions. Even though dentin is usually considered as an entity, different parts of dentin may have special qualitative properties that help dentin to meet all of its required demands. The aim of this review is to provide an overview of the basic structure and composition of dentin, including the collagenous components of the dentin organic matrix and minerals. We also describe the specific structural and functional features of the dentin-enamel junction ( DEJ), mantle dentin, inter- and peritubular dentin, and pulp stones. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) are a family of peptidases trapped within mineralized dentin matrix and involved with degradation of the extracellular matrix components in hybrid layers and caries. Despite their identification through indirect evidences and biochemical assays, MMP‐2 and ‐9 have not been localized within the human dentin extracellular organic matrix. Thus, this study aimed to assess the localization and distribution of MMP‐2 and ‐9 in human dentin organic matrix by employing a correlative field emission in‐lens‐scanning electron microscopy (FEI‐SEM) and transmission electron microscopy (TEM) immunohistochemical approach. Dentin specimens were submitted either to a preembedding or to a postembedding immunolabeling technique using primary monoclonal antibodies anti‐MMP‐2 and anti‐MMP‐9 and exposed to a secondary antibody conjugated with gold nanoparticles. MMP‐2 and ‐9 labelings were identified in the demineralized dentin matrix as highly electron‐dense gold particles dispersed on the collagen fibrils. Correlative FEI‐SEM/TEM observations confirmed that MMP‐2 and MMP‐9 are endogenous components of the human dentin organic matrix and revealed the three‐dimensional relationship between these proteinases and the collagen fibrils, showing that both antibodies yielded a similar labeling pattern. In conclusion, the results of the study contribute to reveal distinct distribution pattern of gelatinases and support the hypothesis that these enzymes are intrinsic constituents of the dentin organic matrix after decalcification. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009 [ABSTRACT FROM AUTHOR]

This study evaluated the permeability properties of five experimental resin membranes that ranged from relatively hydrophobic to relatively hydrophilic to seal acid‐etched dentin saturated with water or ethanol. The experimental resins (R1, R2, R3, R4, and R5) were evaluated as neat bonding agents or as solutions solvated with ethanol (70% resin/30% ethanol). The quality of dentin sealing by these experimental resins was expressed in terms of reflection coefficients calculated as the ratio of the effective osmotic pressure to the theoretical osmotic pressure of test solutions. The effective osmotic pressure produced across resin‐bonded dentin was induced in hypertonic solutions (CaCl2 or albumin) at zero hydrostatic pressure. The outward fluid flow induced by these solutions was brought to zero by applying an opposing negative hydrostatic pressure. The least hydrophilic resins blends, R1 and R2, exhibited significantly (p < 0.05) higher reflection coefficients than the most hydrophilic resins (R4 and R5) in both conditions of dentin saturation (water and ethanol). The reflection coefficients of neat resins were, in general, significantly higher when compared with their corresponding solvated versions in both conditions of dentin saturation. In dentin saturated with ethanol, bonding with neat or solvated resins, resulted in reflection coefficients that were significantly higher when compared with the results obtained in dentin saturated with water. Reflection coefficients of CaCl2 (ca. 1 × 10−4) were significantly lower (p < 0.05) than for albumin (ca. 3 × 10−2). Application of hydrophobic resins may provide better sealing of acid‐etched dentin if the substrate is saturated with ethanol, instead of water. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

It is thought that increasing the strength of the dentin matrix using crosslinking agents may improve both the strength and the durability of resin–dentin bonds. The purpose of this study was to evaluate the effect of two collagen crosslinking agents (glutaraldehyde, GD and grape seed extract, GSE) on the modulus of elasticity of demineralized dentin. Sound molar fragments were fully demineralized and divided into five groups according to the type and concentration of crosslinking agents: 2.5% GD; 5% GD, 25% GD; 0.65% GSE; 6.5% GSE. Specimens were immersed in their respective solution and tested at baseline, 10 min, 30 min, 1 h, 2 h, 4 h. The elastic modulus of dentin was significantly affected by the treatment (p < 0.01) and exposure time (p < 0.01). There was a statistically significant interaction between the two factors evaluated (treatment vs. time p < 0.01). Mean baselines values varied between 4.8 and 6.2 MPa in water; after 4 h of treatment the values increased between 34.9 and 242.5 MPa, that were treatment time and agent dependent. The use of these collagen crosslinkers to increase the stiffness of demineralized dentin, was both concentration and time dependent. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Dentin bonding relies on complete resin impregnation throughout the demineralised hydrophilic collagen mesh. Chondroitin sulphate‐glycosaminoglycans are claimed to regulate the three‐dimensional arrangement of the dentin organic matrix and its hydrophilicity. The aim of this study was to investigate bond strength of two etch‐and‐rinse adhesives to chondroitinase ABC treated dentin. Human extracted molars were treated with chondroitinase ABC and a double labeling immunohistochemical technique was applied to reveal type I collagen and chondroitin 4/6 sulphate distribution under field emission in‐lens scanning electron microscope. The immunohistochemical technique confirmed the effective removal of chondroitin 4/6 sulphate after the enzymatic treatment. Dentin surfaces exposed to chondroitinase ABC and untreated specimens prepared on untreated acid‐etched dentin were bonded with Adper Scotchbond Multi‐Purpose or Prime and Bond NT. Bonded specimens were submitted to microtensile testing and nanoleakage interfacial analysis under transmission electron microscope. Increased mean values of microtensile bond strength and reduced nanoleakage expression were found for both adhesives after chondroitinase ABC treatment of the dentin surface. Adper Scotchbond Multi‐Purpose increased its bond strength about 28%, while bonding made with Prime and Bond NT almost doubled (92% increase) compared to untreated specimens. This study supports the hypothesis that adhesion can be enhanced by removal of chondroitin 4/6 sulphate and dermatan sulphate, probably due to a reduced amount of water content and enlarged interfibrillar spaces. Further studies should validate this hypothesis investigating the stability of chondroitin 4/6 and dermatan sulphate‐depleted dentin bonded interface over time. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Water sorption decreases the mechanical properties and the bond strengths of resin-bonded dentine. The aim of this study was to evaluate the micropermeability of several self-etching and etch-and-rinse adhesives. Optibond FL, Silorane, Scotchbond 1XT, G-Bond, and DC-Bond were bonded under simulated pulpal pressure. A 10 wt% solution of ammoniacal silver nitrate and a 1 wt% solution of rhodamine B were injected into the pulp chamber at 20 cm of water pressure. The dentine–adhesive interfaces were examined using a confocal scanning microscope. Micropermeability was detected in all the adhesives. DC-Bond, G-Bond, and Scotchbond 1XT showed voids along the resin-bonded interface. Silorane and Optibond FL showed an adhesive layer that was free from water trees and micropermeability. The double staining technique is a method that gives accurate results in the study of the resin-dentine micropermeability. Each class of adhesive has a different distribution of micropermeability. The higher the micropermeability, the higher the risk of defects at the resin–dentine interface, which may represent the pathway for hydrolytic and enzymatic degradation of resin–dentine bonds over time. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) offers a potentially nondestructive quantitative method for measuring the stability of resin films and or resin‐bonded dentin over time. The purpose of this study was to measure the electrical impedance of five experimental dental adhesives of increasing hydrophicities as 30‐μm films and as resin‐bonded coatings on acid‐etched dentin. Resin films or resin‐coated dentin disks were placed in U‐shaped chambers containing pairs of Ag–AgCl electrodes in 0.1M KCl. Electrical impedance spectra were run at day 0, 1, 7, 14, and 21 days. All resin films and resin‐bonded dentin showed increases in capacitance during the first day of storage in electrolyte. This was usually associated with an increase in the pore resistance of the resins. Generally, resin‐bonded dentin gave lower impedance values than their respective resins (resins 1–4) but solvated resin 5 bonded to water‐saturated dentin gave higher capacitance and impedance values than resin 5 films. However, solvated resin 5 films gave higher impedance values than resin 5‐bonded dentin. This behavior was confirmed by TEM examinations of silver uptake into films of neat resin 5 vs. ethanol‐solvated resin 5, where water tree‐like structures seen in the former were not seen in the latter. EIS is useful in examining changes in the capacitance and electrical impedance of very hydrophilic, ionic methacrylate resins. Its utility in detecting degradation in resin‐bonded dentin interfaces remains to be determined in longer term studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

This study was designed to evaluate the micro‐tensile bond strength between a carboxylic resin and dentin, when the dentin surface was modified with an experimental dentin primer. The three primers tested were ED primer II (ED), 0.3% ferric chloride aqueous solution (FE), and ED containing 0.3% ferric chloride (ED/FE). Three commercial dentin conditioners [40% phosphoric acid, 10% NaOCl, and 10% citric acid with 3% ferric chloride (10‐3)] were also used. The coronal surfaces of extracted human molars were ground flat to dentin. The dentin surfaces were treated with phosphoric acid, NaOCl, or with one of the primers. The 10‐3 was used without phosphoric acid or NaOCl as a control. A composite material rod was bonded to the dentin surface with 4‐META/MMA‐TBB resin. After 24‐h immersion in 37°C distilled water, 0.9 mm × 0.9 mm composite‐dentin beams cut from the bonded specimens were stressed to failure in tension at 0.6 mm/min. The bond strengths were also evaluated after 5000 thermocycles. The bond strength of the group ED/FE was significantly higher than those of the 10‐3, ED, and FE. After 5000 thermocycling, 10‐3, ED and FE showed significant decrease in bond strength, although no significant decrease was seen for ED/FE. It was concluded that dentin surface treatment with phosphoric acid, NaOCl, and the ED/FE primer improved the bonding (p < 0.05) between 4‐META/MMA‐TBB resin and dentin, with or without thermocycling, while the bond strengths in the control group fell 34% following 5000 thermocycles. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007 [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the ability of five experimental resins, which ranged from hydrophobic to hydrophilic blends, to seal acid-etched dentine saturated with water or ethanol. The experimental resins (R1, R2, R3, R4, and R5) were evaluated as neat bonding agents (100% resin) or as solutions solvated with absolute ethanol (70% resin/30% ethanol). Fluid conductance was measured at 20 cm H2O hydrostatic pressure after sound dentine surfaces were: (i) covered with a smear layer; (ii) acid-etched; or (iii) bonded with neat or solvated resins, which were applied to acid-etched dentine saturated with water or ethanol. In general, the fluid conductance of resin-bonded dentine was significantly higher than that of smear layer-covered dentine. However, when the most hydrophobic neat resins (R1 and R2) were applied to acid-etched dentine saturated with ethanol, the fluid conductance was as low as that produced by smear layers. The fluid conductance of resin-bonded dentine saturated with ethanol was significantly lower than for resin bonded to water-saturated dentine, except for resin R4. Application of more hydrophobic resins may provide better sealing of acid-etched dentine if the substrate is saturated with ethanol instead of with water. [ABSTRACT FROM AUTHOR]

Self-etching primers and adhesives contain very hydrophilic methacrylate monomers that result in high water sorptions by their polymers. Water sorption plasticizes the polymers and lowers their mechanical properties. The purpose of this work was to rank the hydrophilicity of a series of acidic primers by their Hoy's solubility parameters ( δ) to determine if there was a significant relationship between the δ of polymers and their mechanical properties. A series of six acidic primer blends containing a fixed concentration of phenyl-P but variable amounts of 2-hydroxyethyl methacrylate (HEMA), 2,2 bi[4-(2-hydroxy-3-methacryloyloxy)propane (BisGMA), and triethylene-glycol dimethacrylate (TEGDMA) was formulated and their Hoy's solubility parameters calculated. The polymers were cast into small ‘I’ beams and light-cured. The modulus of elasticity (E) and ultimate tensile strength (UTS) were measured in dry polymers and after immersion in water for 24 h. The results showed significant correlations between E and UTS under dry or wet conditions. Both E and UTS fell significantly when the specimens were immersed in water. After water immersion, the E and UTS showed significant correlations with Hoy's δp values. Both E and UTS correlated significantly with the BisGMA concentration of the polymers, either wet or dry. The percentage changes in E or UTS were significantly correlated with the water sorption of the polymers. [ABSTRACT FROM AUTHOR]

Self-etching primers and adhesives contain very hydrophilic acidic monomers that result in high water sorption/solubilities of their polymers. However, the chemical composition of these products varies widely. The purpose of this work was to vary the chemical composition of experimental self-etching primers and adhesives to determine if the water sorption/solubility of the polymers were affected in a predictable manner. The Hoy's solubility parameters of these mixtures were calculated to permit ranking of the degree of hydrophilicity of the polymers. Water sorption/solubility was measured according to ISO 4049. The results showed highly significant ( R2 = 0.86, P < 0.001) correlations between water sorption and Hoy's solubility parameter for polar forces ( δp) of the polymers. Similar correlations were obtained between polymer solubility and δp. When these results were compared with previously published results obtained with more hydrophobic resins, excellent correlations were obtained, indicating that Hoy's δp values may be used to predict the water sorption behavior of methylmethacrylate polymers. [ABSTRACT FROM AUTHOR]

Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5–2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 ± 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg−1 (24 h) after 6–8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 ± 0.70 RFU mg−1 to > 112.5 RFU mg−1 (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin–dentin bonds over time. [ABSTRACT FROM AUTHOR]

This study examined the water-vapour permeability of thin polymerized resin films fabricated from five co-monomer blends of increasing degrees of hydrophilicity, as measured by their Hoy's solubility parameters. Neat resin films were prepared from five experimental light-curable resins ( n = 10). Each film was mounted in a Fisher permeability cup with 8 g of water placed inside the cup. The experiments were conducted in a modified twin-outlet desiccator connected to a vacuum pump in one outlet to permit a continuous airflow to encourage water evaporation. Weight losses by water evaporation were measured at 3, 6, 9, 24, 30, and 48 h by using an analytical balance. Additional resin films were examined by using transmission electron microscopy (TEM) after immersion in ammoniacal silver nitrate. A significant correlation was observed between the cumulative water loss at 48 h and the Hoy's total cohesive energy density ( δt). Transmission electron microscopy revealed silver-filled channels along film peripheries and silver grains of decreasing dimensions toward the film centres in co-monomer blends 3, 4, and 5 of increasing hydrophilicity. Hydrophilic dentin adhesives polymerized in thin films are prone to water loss by evaporation. This probably accounts for the water droplets seen on the surface of vital-bonded dentin after the application of simplified dentin adhesives. [ABSTRACT FROM AUTHOR]

Presents a study which evaluated the effect of a resin coating consisting of a dentin bonding system and a flowable resin composite on the micro tensile bond strength of a resin cement to dentin in indirect composite restoration. Background on adhesive dentistry; Characteristics of the non carious human premolars extracted for orthodontic reasons; Effect of resin coating on the premolars.

Background: Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal therapy as a scaffold for new bone formation in periodontal defects. It is demineralized, theoretically, to expose osteoinductive or osteoconductive bone matrix proteins that should facilitate osteogenesis. The degree of DFDBA demineralization varies between tissue banks and may affect clinical regeneration. A 2% residual calcium level in DFDBA has been shown to result in the highest alkaline phosphatase activity levels in cultured human periosteal cells and is optimally osteoinductive or osteoconductive for new bone formation. The purpose of this study was to evaluate the effect of 4 different residual calcium levels in commercially available DFDBA samples on porcine osteoclast activity as measured by resorption on calcium phosphate-coated disks. Methods: Bone marrow was harvested from the femurs of 3-week-old farm pigs and cultured for 3 weeks. Hematopoietic stem cells were allowed to differentiate into mature active polykaryons displaying genuine osteoclast characteristics. The osteoclast cells displayed a dense actin band inside the margins of the cytoplasm under light microscopy. Culture media was decanted and collagenase added to free the attached cells. Equal cell samples were pipetted onto calcium phosphate-coated disks in 24-well plates. DFDBA samples with 1.44%, 2.41%, and 5.29% residual calcium; FDBA (30% residual calcium); and control cultures without allograft samples were prepared and all samples incubated for 1 week. Cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP), Oregon Green 488-phalloidin, a stain for cytoskeletal proteins, and counterstained with propidium iodide. Specimens were examined by light and fluorescence microscopy using epi-illumination. Calcium phosphate disks were then rinsed in 5% sodium hypochlorite to remove adherent osteoclasts, and substrate surface changes were measured by white light interferometry and image analysis. Results: A higher yield of TRAP-positive cells was produced without DFDBA; however, resorptive activity appears to be significantly increased in the presence of 2.41% residual calcium as compared to all other experimental groups (P<0.0065). Conclusion: In this in vitro model, porcine osteoclasts show significantly more resorptive activity as measured on calcium phosphate-coated disks in the presence of 2.41% residual calcium in DFDBA than in other DFDBA residual calcium levels. [ABSTRACT FROM AUTHOR]

The purpose of this study was to quantitate the effects of root planing on the permeability of human root dentin in vitro. Unerupted 3rd molars were used. The crowns were removed and longitudinal slices made of the root. The hydraulic conductance of the root dentin was measured before and after root planing, acid etching and potassium oxalate application using a fluid filtration method. The results showed that root planing creates a smear layer that reduces the permeability of the underlying dentin. However, this smear layer is acid labile. Thus, root planing may ultimately cause increased dentin permeability and the associated sequelae of sensitive dentin, bacterial invasion of tubules, reduced periodontal reattachment and pulpal irritation. [ABSTRACT FROM AUTHOR]

Numerous chemical stimuli have been used to elicit pain from exposed dentin. Most of the effective chemicals share a common denominator; they are all very hypertonic. Dentin surfaces covered with a smear layer are much less responsive to hypertonic solutions than dentin devoid of a smear layer. These observations support the hydrodynamic theory of dentin sensitivity. The most important variables influencing the efficacy of chemical stimuli include: ionic composition, presence or absence of calcium, sodium or potassium, pH and osmolality (tonicity). Although hypertonic solutions of sucrose or CaCl&2sub; can be useful qualitative stimuli, the theoretical objections to using them for quantitative evaluation of dentinal sensitivity seem to far out-weight their advantage. [ABSTRACT FROM AUTHOR]

A mechanistic evaluation of gingival fluid is presented in an effort to identify the important physiologic variables that must be measured before one can define the exact mechanism(s) of gingival fluid production. This approach evaluates the Starling factors governing fluid distribution across capillaries by modifying these concepts to fit the unique structures, environment, and functional demands of tissues in and around the gingival sulcus. Many assumptions are made to simplify arguments and to approximate unknowns. Suggestions are made regarding techniques and experimental methods that might be employed to evaluate several important variables. Gingival fluid production is viewed as the result of an increased rate of capillary transudation brought about by the release of mediators of inflammation. These agents are thought to cause both increased capillary pressure and increased leakage of plasma proteins into the interstitial fluid. It is postulated that the low compliance of gingival tissue and the high hydraulic conductance of sulcular epithelium result in this interstitial fluid moving from connective tissue into the sulcus. [ABSTRACT FROM AUTHOR]

The current challenge in adhesive dentistry is to develop dentin bonding systems that will reproducibly achieve high bond strengths similar to those obtained between resins and acid-etched enamel. Some of the limitations of dentin as a bonding substrate are that it changes its structure as it is prepared deeper, it is difficult to dry, and its smear layer is weak. Further, it is difficult to avoid contaminating proximal boxes with blood. Such contamination lowers dentin bond strengths to very low values. Decontamination of such dentin must be done prior to resin placement. The forces of polymerization contraction depend, in part, on the shape of cavities and how they are filled. Bulk filling of class I cavities can lead to conditions in which the forces of polymerization contraction exceed dentin bond strength with some materials and locations. The future development of resin systems that do not shrink on polymerization would eliminate many current problems in adhesive dentistry. [ABSTRACT FROM AUTHOR]

The ability of 3 formulations of a hard-setting calcium hydroxide-containing base material (dycal®) to seal dentinal tubules was evaluated in an in vitro model. The latest light-cured generation of the material was clearly superior to the previous formulations at all time periods tested. [ABSTRACT FROM AUTHOR]

Lidocaine ointment applied topically to gingivae of vital teeth with exposed dentin caused acute, severe pain. Measurement of the osmotic pressure of the ointment revealed that it was very hypertonic, due mainly to the high concentration of polyethylene glycol vehicle. The results support the hydrodynamic theory of dentin sensitivity. [ABSTRACT FROM AUTHOR]

The article presents the author's views on a paper by Safak Külünk and colleagues that evaluated the effects of various desensitizing agents on the bond strength of Panavia. The author states that the results of the study is limited because it evaluated only one resin cement, which is Panavia F 2.0.

The article provides an answer to a question on the best way to rewet the dentin.

The article comments on the study of Dr. Magne and colleagues concerning the effects of the use of an air syringe versus high-speed suction tip on the bond strength of Optibond FL dental adhesive system in extracted tooth. Accordingly, the study made the results more clinically relevant by preparing cavities with a diamond bur. It suggests that Dr. Magne and colleagues should repeat the study with more techniques-sensitive systems, such as single-bottle and etch-and-rinse products.

Demonstrates that an adhesive primer containing a methacrylate derivative of dodecylpyridinium bromide (MDPB) can have bactericidal activity on contaminated dentin from arrested carious lesions. Problem with incorporating MDPB into polymerized comonomer blends; Information on benzalkonium chloride; Use of tertiary butylaminoethyl methacrylate.

The article discusses the possible effects of direct and indirect dental bleaching on the fracture toughness of human dentin after 2 months of bleaching. Studies show that direct exposure to bleach produced similar reductions in material properties. No such effects were seen when intact enamel was present.

Presents a commentary on the study "Influence of Temperature on the Spreading Velocity of Simplified-Step Adhesive Systems," by Atta and colleagues. Composition of almost all dental bonding systems; Method that could reduce increases in viscosity; Defects detected in the dental adhesives comprising of higher-acetone content.