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PubMed1999

The combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules.

Various methods and materials used in the treatment of dentin hypersensitivity are thought to achieve a therapeutic benefit by tubule occlusion. The aim of the present study was to evaluate the combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules. Thirty-six dentin specimens with exposed dentinal tubule orifices were used in this study. The samples were randomly divided into four groups. Groups A, B, and C were varnished by sodium fluoride, whereas group D served as a control. Then, group C was lased by 30 mJ of Nd:YAG laser, 10 pulses/s for 2 min by light painting. Three hours later, groups B and C were brushed by an electrical toothbrush for 30 min. Under SEM observation, the control group showed numerous exposed dentinal tubule orifices, and the sodium fluoride varnished specimens showed closure of exposed dentinal tubule orifices. After electrical toothbrushing, most of the sodium fluoride varnish was brushed away, except in the specimens that were irradiated by Nd:YAG laser. Over 90% of the dentinal tubule orifices were occluded by sodium fluoride varnish combined with Nd:YAG laser irradiation.

Combined Modality Therapy↗

PubMed1999

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

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

Dentifrices↗

PubMed2001

An update on the physiology of the dentine-pulp complex.

The properties of dentine and pulp are closely related and from a functional standpoint these tissues are often referred to as the dentine-pulp complex. In recent years there has been considerable progress in our understanding of the physiology of the dentine-pulp complex. This review describes some of the advances that are relevant to clinical dentistry, including dentine permeability, dentine bonding, dentine sensitivity, the properties of pulpal nerves and blood vessels and the reactions of the dentine-pulp complex to operative dental procedures.

Dental Bonding↗

PubMed2002

The effects of outward forced convective flow on inward diffusion of potassium across human dentin.

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.

Analysis of Variance↗

PubMed2004

In vitro evaporative vs. convective water flux across human dentin before and after conditioning and placement of glass-ionomer cements.

PURPOSE: To assess the convective and evaporative fluid movement across glass-ionomer treated dentin. METHODS: Crown segments made from extracted human teeth, were divided into two groups of 14 teeth each. Each segment was cemented onto a plexiglass slab penetrated by a stainless steel tube, permitting filling of the pulp chamber with water. This set-up was attached to a device that measured fluid movement through the dentin in the crown segment. The experimental design involved repeated measurements of convective and evaporative fluid movements in each of the following conditions: smear layer-covered dentin, conditioned dentin, dentin after placement of one of two glass-ionomers (Fuji IX or Ketac-Molar), with and without a protective coating. The same water fluxes were remeasured after storage of the samples for 24 hours in distilled water. RESULTS: Statistical analysis of the results using ANOVA indicated a significant difference between the two measured water fluxes (P < 0.001). There was also a significant difference between the two materials (P < 0.001), with Ketac-Molar allowing higher permeability than Fuji IX. Conditioning the dentin surface with polyacrylic acid increased the convective water flux (P < 0.05) but did not change the evaporative water flux. Placement of the glass-ionomer material did not change the rate of spontaneous evaporation of water from the dentin, but the application of a coating agent reduced the evaporative water loss. These values were not significantly different when the specimens were stored for 24 hours.

Acrylic Resins↗

PubMed1997

ArF excimer laser irradiation of human dentin.

BACKGROUND AND OBJECTIVE: The use of excimer lasers for treatment of dental hard tissues has considerable potential because the combined characteristics of low wavelength and short pulse result in limited heat diffusion and, therefore, tissue ablation without the problems of collateral damage. To date, there are relatively few published studies concerning the effects of excimer laser irradiation on dental hard tissues. Thus the present study was conducted to examine the morphological changes in tooth dentin subsequent to ArF excimer laser irradiation. STUDY DESIGN/MATERIALS AND METHODS: The morphologic changes induced in normal, nondiseased human dentin following irradiation by an ArF excimer laser at fluences ranging from 1 to 4 J/cm2 and the number of laser pulses ranging from 50 to 1,000 were evaluated by scanning electron microscopy. RESULTS: Two modes of ablation, photochemical at low fluences and thermal at high fluences, were observed. A fluence of 1 J/ cm2 when combined with 50 or 100 pulses produced a uniform ablation of the dentin surface without signs of tissue melting. At fluences > 1.5 J/cm2, the thermal mode of ablation was more efficient at removing intertubular dentin than peritubular dentin. Further, when compared to the lower fluences, the higher settings produced a rougher ablation crater surface. Additionally, the higher fluences produced surface melting with each pulse and sealing of exposed dentinal tubules after irradiation with 100-300 laser pulses. CONCLUSIONS: The photochemical and thermal mechanisms of tooth dentin ablation were identified based on significant differences in tissue morphology following laser irradiation. The rates of tissue ablation and the observed morphologic changes indicate that the ArF excimer laser could be useful for caries removal and sealing of exposed dentinal tubules.

Dentin↗

PubMed1996

Absorption of iron by dentin: its role in discoloration.

This study investigated the effect of iron-containing mordants on the discoloration of human dentin. Dentin wafers with intact enamel borders were treated with one of several acid solutions containing iron. After exposure to aqueous sodium sulfide, color change was evaluated colorimetrically. X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectrometry (EDS) were used to probe surfaces for the presence of iron. Changes in surface morphology were evaluated by scanning electron microscopy (SEM). The results indicated that dentin treated by iron-containing solutions always discolored when the sodium-sulfide concentration exceeded 9.7 mM; variability in discoloration occurred below this level. XPS detected iron in enamel but not in dentin, while EDS detected iron in both enamel and dentin. Since XPS probes the upper atomic layers, these results indicate that acid-demineralized dentin absorbs iron; however, a water wash removes iron from the uppermost dentin surface, suggesting that the iron is physically absorbed. When exposed to sodium sulfide, at least some of the iron remaining in the bulk region is able to migrate to the surface to form iron-sulfide compounds. Based on SEM findings, discoloration is associated with the formation of a surface film on dentin.

Absorption↗

PubMed2004

Ultrastructure and nanomechanical properties of cementum dentin junction.

The attachment between cementum and dentin has been given several definitions and nomenclature, including: interzonal layer, intermediate cementum, collagen hiatus, Hopewell-Smith's hyaline layer, and more commonly, cementum-dentin junction (CDJ). Understanding the attachment of two structurally dissimilar hard tissues such as cementum and dentin defined by a junction may provide information necessary to engineer functionally graded materials that can be used for efficient tooth restorations in clinical dentistry and other bioengineering applications. Hence, in this study, as a first step toward understanding the CDJ using a biomechanical approach, it was hypothesized that the CDJ between cementum and dentin is a wide zone with mechanical properties significantly lower than the neighboring tissues. The structure of the CDJ was studied using an atomic force microscope (AFM), and site-specific mechanical response of the three regions; cementum, CDJ, and dentin were determined using an AFM-nanoindenter under dry and wet conditions. The AFM results of the CDJ demonstrated a valley under dry conditions and a peak under wet conditions. The magnitude of the depth of the valley was approximately the same as the height of the peak of the CDJ, ranging from 10 to 40 microm. The nanomechanical properties under dry conditions indicated no significant difference (p > 0.05) in elastic modulus and hardness of the CDJ (Er = 17.5 +/- 2.7 GPa, H = 0.6 +/- 0.1 GPa) and cementum (Er = 18.7 +/- 2.5 GPa, H = 0.6 +/- 0.1 GPa). The mechanical properties of the CDJ were significantly lower (p << 0.05) than dentin (Er = 19.9 +/- 2.9 GPa, H = 0.6 +/- 0.1 GPa) under dry conditions. However, under more relevant hydrated conditions, the mechanical properties of CDJ (Er 3.0 +/- 0.7 GPa, H = 0.1 +/- 0.0 GPa) were significantly lower (p << 0.05) than those of cementum (Er 6.8 +/- 1.9 GPa, H = 0.2 +/- 0.1 GPa) and dentin (Er 9.4 +/- 2.3 GPa, H = 0.3 +/- 0.1 GPa). Based on the results from this study, it can be concluded that the CDJ can be regarded as a wide zone containing large quantities of proteins including collagen that contribute to hydration and significantly reduce mechanical properties, compared with the adjacent hard tissues, cementum, and dentin. The lower mechanical properties of the CDJ may make it possible for it to redistribute occlusal loads to the alveolar bone.

Aged↗

PubMed2006

Hydration and dynamic fatigue of dentin.

An experimental investigation on the dynamic fatigue response of dentin was conducted to examine the influence of stress rate on the strength and energy to fracture. Rectangular beams were prepared from the coronal dentin of bovine maxillary molars and subjected to four-point flexure to failure. The dentin beams were examined in the fully hydrated and dehydrated condition at stress rates (sigma) ranging from 0.01 to 100 MPa/s. Results for the hydrated dentin showed that the flexure strength, energy to fracture, and flexure modulus all increased with increasing stress rate; the flexure strength increased from 100 MPa ((sigma) = 0.01 MPa/s) to 250 MPa ((sigma) = 100 MPa/s). In contrast, the elastic modulus and strength of the dehydrated dentin decreased with increasing stress rate; the flexural strength of the dehydrated dentin deceased from 170 MPa ((sigma) = 0.01 MPa/s) to 100 MPa ((sigma) = 100 MPa/s). While the hydrated dentin behaved more like a brittle material at low stress rates, the strain to fracture was found to be nearly independent of (sigma). According to the experimental results, restorative conditions that cause development of static stresses within the tooth could promote a decrease in the damage tolerance of dentin.

Animals↗

PubMed2006

Attachment of human epithelial cells and periodontal ligament fibroblasts to tooth dentin.

A goal of treatment in periodontal therapy is to regenerate a new fibroblastic attachment rather than to repair lost attachment with a long junctional epithelium. To date, there is no evidence that fibroblastic attachment formed during regeneration is stronger or less susceptible to periodontal breakdown than a long junctional epithelial attachment. We measured the rate and strength of attachment of epithelial cells (NHEK) and periodontal ligament fibroblasts (PDLF) cultured individually and cocultured to dentin surfaces to determine which cell type has a faster attachment rate and greater adhesive strength to human dentin, and whether the cell types attach independently. Longitudinal dentin slices were seeded with either PDLF or NHEK for 2 or 24 h. The specimens were placed into a parallel plate flow chamber and defined laminar shear stresses were applied. Shear stress was created by step increases in fluid flow rate. Effluent fluid was collected and cell numbers (detached) were counted using a hemocytometer. Cocultures of PDLF and NHEK at three seeding ratios (10:1, 1:1, 1:10) were also tested. Each cell type attached equally well to polystyrene or dentin. PDLF showed a stronger attachment to polystyrene and dentin at 24 versus 2 h. NHEK attached to polystyrene or dentin equally well at 2 and 24 h. NHEK were more strongly attached after 2 h when compared to PDLF. PDLF were more strongly attached after 24 h versus NHEK. When NHEK and PDLF were seeded together on dentin at a 1:1 ratio, PDLF appeared to be more strongly attached than NHEK at 2 but not 24 h. At a ratio of 10 PDLF:1 NHEK, PDLF appeared to be more strongly attached at 2 and 24 h. At a ratio of 1 PDLF:10 NHEK, NHEK appeared to be more strongly attached at 2 h, but PDLF showed a trend of stronger attachment at 24 h. We conclude that epithelial cells attach more quickly to dentin surfaces than PDLF, but do not demonstrate increased attachment strength over time (PDLF do show increased attachment strength overtime). The purported advantages of periodontal regeneration over periodontal repair are supported by our results. Furthermore, our results support the concept of guided tissue regeneration. On the basis of on cellular competition experiments, epithelial cells and PDLF do not act independently, because epithelial cells enhanced the attachment rate of PDLF.

Cell Adhesion↗

PubMed2004

Induction of cyclooxygenase-2 mRNA and protein expression by dentin bonding agents in human gingival fibroblasts.

An ideal dentin bonding agent should be nonirritating to surrounding tissues. Unfortunately, all histological investigations have demonstrated that dentin bonding agents can induce mild to severe inflammatory alterations. However, there is little information on the precise mechanisms about dentin bonding agents-induced inflammatory reaction. Cyclooxygenase-2 (COX-2) is an inducible enzyme believed to be responsible for prostaglandin synthesis at the site of inflammation. The aim of the present study was to investigate the effects of three dentin bonding agents, Clearfil SE Bond, Prime & Bond NT, and Single Bond on the expression of COX-2 mRNA gene and protein in cultured human gingival fibroblasts. The exposure of quiescent human gingival fibroblasts to dentin bonding agents resulted in the induction of COX-2 mRNA expression. The investigations of the time-dependent on COX-2 mRNA expression in dentin bonding agent-treated human gingival fibroblasts revealed different patterns. The influence of COX-2 mRNA depended on the tested materials. In addition, all dentin bonding agents also induced COX-2 protein expression in human gingival fibroblasts. Taken together, the activation of COX-2 expression may be one of the potential mechanisms of dentin bonding agent-induced gingival inflammation.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2005

Bonding performance of different adhesive systems to deproteinized dentin: microtensile bond strength and scanning electron microscopy.

Deproteinization has been shown to optimize dentin bonding, but differences in adhesive composition should be considered. The objective of this study was to evaluate the effect of dentin deproteinization on microtensile bond strength (microTBS) of four total-etch adhesive systems (Single Bond/SB, Prime & Bond NT/PB, One Coat Bond/OC, and PQ1/PQ). The ultrastructure of the resin-dentin interfaces was also examined using scanning electron microscopy. Tukey's multiple-comparison tests indicated that PB and PQ produced significantly higher microTBS (p<0.05) after dentin deproteinization (PB=61.53 MPa, PQ=58.18 MPa). This treatment provided statistically lower results for SB (39.08 MPa), but the microTBS of OC to dentin was unaffected by dentin deproteinization. The bonding performance on deproteinized dentin surfaces depended on the characteristics of each adhesive system, as well as the adhesive dentin specificity to the oxidant effect of sodium hypochlorite. Incorporation of fillers in the adhesive, a possible self-etching action, and the presence of a volatile solvent (acetone) were the main factors for a better union between the adhesive system and deproteinized substrate.

Adhesives↗

PubMed2003

Wavelength and average power density dependency of the surface modification of root dentin using an MIR-FEL.

BACKGROUND AND OBJECTIVES: Surface modification of root dentin by mid-infrared (MIR) pulsed-laser irradiation is one of the candidates for a novel, non-invasive treatment to prevent root surface caries. To modify root dentin effectively and non-invasively it is essential to estimate quantitatively and qualitatively the laser parameters, such as the wavelength and power density, required for surface modification. The key aspect is to bring about effective surface modification of the root dentin while minimizing the unwanted removal of the underlying dentin. STUDY DESIGN/MATERIALS AND METHODS: Using a tunable, MIR Free Electron Laser with lambda = 8.8-10.6 microm, we have investigated macroscopically the extent of the surface modification (morphological and chemical changes) of root dentin. We have obtained experimental results related to the ablation depth, the MIR absorption spectrum, and the elemental chemical composition. RESULTS: The observations showed that the surface modification of root dentin was inclined toward well-recrystallized HAp-like material, leading to an increase in the acid resistance and dentinal tubule sealing. The laser parameters, at which efficient surface modification without enhanced ablation occurred, were estimated to be approximately in the wavelength region around lambda = approximately 9.0 or approximately 9.7 microm and in the average power density region of approximately 10-20 W/cm2 (resulting in total energy density and peak power density regions of approximately 1-2 kJ/cm2 and approximately 0.67-1.2 kW/cm2). CONCLUSIONS: The surface modification of root dentin strongly depends on the laser parameters applied. We conclude that the optimum wavelengths for laser treatment of root surface caries are lambda = approximately 9.0 or approximately 9.7 microm, corresponding to the absorption peak due to P-O stretching.

Animals↗

PubMed1993

Dentin sialoprotein: biosynthesis and developmental appearance in rat tooth germs in comparison with amelogenins, osteocalcin and collagen type-I.

A non-collagenous protein, extracted from rat incisor dentin, is a dentin sialoprotein (DSP). We examined immunohistochemically the developmental appearance and tissue distribution of DSP in 1 to 3-day-old rat molar and incisor tooth germs. The earliest staining for DSP was observed in newly differentiated odontoblasts. In more advanced stages, immunostaining for DSP gradually increased in pre-dentin, odontoblasts and dentin, and appeared in many cells of the dental papilla. In early stages of development before the breakdown of the dental basement membrane, pre-ameloblasts were also positive for DSP. This staining disappeared from the ameloblast cell body soon after deposition of the first layer of mineralized dentin. Radiolabelling of tooth matrix proteins with 14C-serine in vitro followed by immunoprecipitation and fluorography confirmed that DSP was synthesized by tooth-forming cells. The immunolocalization for DSP was different from that of either collagen type-I, osteocalcin or the amelogenins. Whereas collagen type-I and osteocalcin were restricted to the mesenchymal dental tissues, the amelogenins were detectable in both epithelial and mesenchymal dental cells and tissues at the epithelio-mesenchymal interface at early stages of development, prior to the onset of dentin mineralization. We conclude that DSP is expressed in and secreted by odontoblasts and some dental papilla cells from early stages of dentinogenesis onwards, i.e. later than type-I collagen, but before deposition of the first layer of mineralized dentin. In pre-mineralizing stages, some of the matrix proteins may be endocytosed from the pre-dentin by both cell types involved in the epithelio-mesenchymal interaction.

Amelogenin↗

PubMed1977

On the state of anionic groups of demineralized matrices of bone and dentine.

Calcium-binding and biochemical studies have been applied to characterize the state of the carboxylate and protein-bound phosphate groups in the EDTA-demineralized matrices of rat bone and dentine. The organic phosphate and carboxylate content of demineralized bone is virtually identical to that of purified steer skin collagen whereas demineralized dentine has a significantly higher phosphate and carboxylate content, presumably due to the presence of an acidic non-collagenous phosphoprotein. Two classes of calcium-binding sites can be detected in demineralized bone, demineralized dentine, and purified, reconstituted collagen. The number of strong calcium-binding sites correlates with the number of protein-bound phosphate groups. Depending on the preparative procedure, seven to nine such sites (per collagen molecule) are present in dentine, and one to two in the purified reconstituted collagen and in bone. The binding constant for the dentinal sites (1.1 X 10(4) M-1), however, is 20 times greater than that for bone or reconstituted collagen fibrils from skin. We tentatively conclude that the strong calcium-binding site in bone and reconstituted collagen is of the form protein-PO-4Ca++ whereas in dentine it is of the form protein (formula: see text); the weak binding sites in bone and dentine are of the form protein-COO-Ca++; and that approximately 160 of the 217 carboxylate groups of the collagen molecules of dentine or bone are present as electrostatic linkages of the form protein-COO-+H3N-protein.

Animals↗

PubMed2004

Immunohistochemical characterization of rapid dentin formation induced by enamel matrix derivative.

The purpose of this study was to examine the pulpal expression of dentin-related proteins during enamel matrix derivative (EMD)-induced reparative dentin formation in a pulpotomy model in pig incisors. Pulpotomies were performed on 72 lower incisors in 24 adult miniature swine. The exposed pulp tissue was treated with EMD or covered with a calcium hydroxide paste (Dycal). At predefined time-points, ranging from 4 days to 12 weeks, experimental teeth were extracted and examined by use of light microscopy, and expression of dentin-related proteins in the pulps was investigated by immunohistochemistry, using antibodies against type I collagen, dentin sialoprotein (DSP), sheathlin, and EMD. In all EMD-treated teeth a substantial amount of reparative dentin formation was observed. The amount of reparative dentin in calcium hydroxide-treated teeth was significantly smaller than in EMD-treated teeth (P < 0.005) and was less effective in bridging the pulpal wounds. Immunohistochemistry demonstrated that enamel matrix proteins were present in detectable amounts at the application site for about 4 weeks. Moreover, the expression of proteins related to dentin formation in the wounded pulp tissue was about 2 weeks advanced in EMD-treated teeth. These findings demonstrate that enamel matrix molecules have the capacity to induce rapid pulpal wound healing in pulpotomized teeth, and suggest that the longevity and continued presence of enamel matrix macromolecules at the application site can be utilized to stimulate growth and repair of dentin over a period consistent with a favorable clinical outcome.

Animals↗

PubMed2026

Proteomic profile of the dentine pellicle modified with plant polyphenols and fluoride.

OBJECTIVES: Despite its protective role, the dentine pellicle has rarely been studied, therefore we aimed to map out the proteomic profile of in vitro dentine pellicles before and after modification. MATERIALS AND METHODS: A total of 135 human dentine specimens were prepared. After initial pellicle formation with 150 µl pooled human saliva (37 °C, 30 min), the dentine specimens were immersed in one of 9 pellicle modification solutions (2 ml/specimen): deionized water (non-modified pellicle), SnCl2/NaF/AmF (commercial solution containing 800 ppm Sn2+ and 500 ppm F-), NaF solution (500 ppm F- ), and six polyphenol solutions (2 mg / ml) with or without 500 ppm F-: blueberry extract (BBE and BBE + F-), green tea extract (GTE and GTE + F-) and grape seed extract (GSE and GSE + F-). After another aliquot of saliva (150 µl, 37 °C, 60 min), the pellicles were harvested with sodium dodecyl sulphate by rubbing with cotton balls, and taken to proteomic analyses by Liquid Chromatography-Tandem Mass Spectrometry after tryptic digestion. RESULTS: A total of 382 proteins were identified in all the proteomic analyses for all groups. Pellicle modification with fluoride, either NaF or SnCl2/NaF/AmF, led to the presence of 12 or 14 exclusive proteins, respectively, whereas modification with the solutions containing polyphenols presented less exclusive proteins (4-6 proteins). The number of exclusive proteins was even lower for when polyphenols and fluoride (GTE + F- and GSE + F-) were used, with lower abundance of proteases. CONCLUSIONS: We conclude that NaF and SnCl2/NaF/AmF significantly modify the proteome of the dentine pellicle. The combination of fluoride with polyphenols further lowers the abundance of proteins and proteases, which explains the positive effect of these solutions on the dentine pellicles. CLINICAL RELEVANCE: Plant extract solutions with fluoride can significantly modify the proteomic structure of the dentine pellicle, which clarifies the mechanism of action of polyphenols on the protection of dentine demineralization.

Humans↗

PubMed2007

Shear bond strengths of glass-ionomer cements to sound and to prepared carious dentine.

The aim of this study was determine whether bonding of glass-ionomer cements to non-carious dentine differed from that to carious dentine. Five commercial cements were used, namely Fuji IX GP, Fuji IX capsulated, Fuji IX Fast capsulated (all GC, Japan), Ketac-Molar and Ketac-Molar Aplicap (both 3M-ESPE, Germany). Following conditioning of the substrate with 10% poly (acrylic acid) for 10 s, sets of 10 samples of the cements were bonded to prepared teeth that had been removed for orthodontic reasons. The teeth used had either sound dentine or sclerotic dentine. Shear bond strengths were determined following 24 h storage. For the auto-mixed cements, shear bond strength to sound dentine was found not to differ statistically from shear bond strength to sclerotic dentine whereas for hand-mixed cements, shear bond to sound dentine was found to be higher than to carious dentine (to at least p < 0.05). This shows that the chemical effects arising from interactions of glass-ionomer cements with the mineral phase of the tooth are the most important in developing strong bonds, at least in the shorter term.

Biomechanical Phenomena↗