Dentin Pretreatment Research Articles

Bonding ability of self-adhesive resin-cements after dentin biomodification with hyaluronic acid

Purpose: The present study evaluated the influence of the hyaluronic acid (HA) on the bonding ability of self-adhesive resin cements to dentin regarding the bond strength. Eighty bovine incisors were ground flat to obtain a 2-mm thick slices which received conical preparations. The specimens were randomly distributed into 4 groups (n = 15) according to the dentin pretreatment (1 – control: untreated dentin; 2 – application of HA) and the evaluation time (1 – control: immediate evaluation; 2 – hydrolytic degradation: 6 months of storage in water at 37 °C). Preparations received the application of a self-adhesive resin cement (RelyX U200 or MaxCem Elite). Push-out bond strength test was conducted (0.5 mm/min). The bond strength data was submitted to two-way ANOVA/Tukey’s test (α = 0.05). For U200, no significance was observed when comparing the immediate (24 h) and 6 months means for the control groups (unexposed specimens). Previous application of HA to dentin significantly reduced the bond strength of U200 to dentin in both evaluation times (p < 0.05). HA had no significant influence on the push-out bond strength means for the cement MAX in both evaluation times (p > 0.05). The type 1 failure mode (adhesive mode) occurred in 100% of the specimens, irrespective of the dentin treatment or evaluation times. Pretreatment of dentin with HA produces a material-dependent influence on the push-out bond strength. The bonding ability of RelyX U200 is negatively influenced by the pretreatment of dentin with HA, whereas the biomodification of dentin with this bioactive agent causes no impact for the cement MaxCem Elite.

Influence of dentin pretreatment with 2.5% titanium tetrafluoride on inhibiting caries at the tooth-restoration interface in situ

ObjectiveInvestigate the effects of dentin pretreatment with 2.5% titanium tetrafluoride (TiF4) aqueous solution followed by two-step self-etching (CLE/Clearfil SE Bond) and one-step self-etching adhesive systems (SBU/Single Bond Universal) on carious lesion inhibition at the tooth-restoration interface using an in situ model. DesignSixty-four cavities at the enamel-dentin junction of dental fragments were randomly distributed according to groups (n=16): 1) TiF4+CLE; 2) TiF4+SBU; 3) CLE; 4) SBU. Cavities were restored using resin composite, and placed in intraoral palatal devices used by 16 volunteers for 21days, to induce caries formation in situ. The fragments were then ground-flat to perform Knoop microhardness tests. Nine indentations were performed on each enamel and dentin substrate, subjacent to the restoration. Analysis of variance and Tukey’s test were applied. ResultsEnamel: groups receiving TiF4 dentin pretreatment (regardless of adhesive system and tooth-restoration interface distance) presented higher hardness means at a depth of 25μm from the outer tooth surface (p<0.0001). Dentin: groups receiving CLE presented higher means when applying TiF4 pretreatment, whereas groups restored with SBU presented higher means without pretreatment (p=0.0003). ConclusionsDentin pretreatment with TiF4 inhibited demineralization of the enamel interface in situ, regardless of the adhesive, and TiF4 pretreatment followed by CLE application showed higher potential for inhibiting dentin demineralization at the interface.

Role of Proteolytic Enzyme Inhibitors on Carious and Eroded Dentin Associated With a Universal Bonding System.

The aim of this study was to evaluate the effect of proteolytic inhibitors on the bond strength of a universal adhesive system (etch-and-rinse mode) applied to artificial carious and eroded dentin. Ninety molars were prepared and randomly divided into three groups according to the substrate: N, no challenges; ACD, artificial carious dentin simulation and ERO, artificial erosion simulation with orange juice. All groups were redivided into three subgroups according to the dentin pretreatment: W, water; CHX, 2% digluconate chlorhexidine; and E-64 (trans-epoxysuccinyl-L-leucylamido-[4-guanidino] butane), 5 μM E-64 inhibitor. They constituted a total of nine groups (n=10): N-W, N-CHX, N-E64, ACD-W, ACD-CHX, ACD-E64, ERO-W, ERO-CHX, and ERO-E64. All specimens were restored with Adper Single Bond Universal/Filtek Z250. Beams (0.64 mm2) were obtained and subjected to the microtensile test (μTBS) in a universal testing machine at 0.5 mm/min. The failure mode of the interfaces was determined by optical microscopy (40× magnification). Data were statistically analyzed by three-way analysis of variance and Tukey tests (p<0.05). All individual factors (p<0.0001) and the interaction between substrate and treatment (p=0.0011) and between substrate and time (p=0.0003) were statistically significant. The caries substrate contributed negatively to bond strength. Chlorhexidine reduced bond strength for normal and eroded conditions. Only the normal substrate was negatively affected by time despite the pretreatment. The universal bonding system appears to be a promising bonding strategy for the maintenance of bond strength to affected dentin. E-64 did not affect bonding to the dentin in contrast to the use of chlorhexidine, which, when associated with the universal system, did affect the microtensile bond strength for artificial carious dentin.

Effect of carbodiimide on the bond strength and durability of resin-dentin interface

The effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on the bond strength and durability of the resin-dentin interface using a three-step etch-and-rinse and a universal adhesive (UA) system was investigated. Additionally, the effect of dry and wet bonding on the interface created by UA was evaluated. Investigations carried out were scanning electron microscopy (SEM) evaluation, interfacial nanoleakage expression (NE) and micro-tensile bond strength (μ-TBS) testing. Dentin surfaces of sound molars were acid-etched, pretreated with 0.3 M EDC followed by adhesive application and restored with composite incrementally. Resin-dentin beams for μ-TBS testing and resin-dentin slabs for SEM and NE were sectioned. At 24 h, pre-treatment with EDC did not significantly change the μ-TBS and NE of any of the adhesives compared to their respective controls. There is a significant decrease in the μ-TBS and significant increase in NE after 1 yr of storage compared to the 24 h results. UA in dry bonding conditions pretreated with EDC had higher μ-TBS values than its control. Pre-treatment of acid-etched dentin with 0.3 M EDC for 1 min enhanced the bond strength and durability of the resin-dentin interface created by the tested adhesives. Application of UA in a wet bonding technique appeared less effective than dry bonding technique.

IMPACT OF VARIOUS RESIN ADHESIVE STRATEGIES ON MICRO SHEAR BOND STRENGTH TO SOUND, CARIES- AFFECTED AND REMINERALIZED DENTIN SUBSTRATES: AN IN-VITRO ESEM ANALYSIS

Objectives: The aim of this in vitro study was to evaluate the micro shear bond strength of different adhesive system strategies to sound, artificially caries affected and remineralized dentin substrates.Materials and Methods: Sixty bovine permanent incisors were used. The labial enamel was removed and a flat dentin surface was obtained. The dentin specimens were divided into three main groups (sound as a control, artificial caries affected and remineralized dentin groups). Four adhesive systems were applied over the different dentin substrates according to the directions of the manufacturers; (Futurabond M+, Single bond universal (universal adhesives used in self-etch mode, Futurabond DC (Dual- curing self etch bond with nanofillers and Solobond M (Etch and rinse adhesive). After preparation of the 240 micro tubules of resin composite (Filtek TM Z350XT (Flow able restorative), micro shear bond strength test was performed. The results were tabulated and statistically analyzed. Failure mode was detected for all the fractured dentin specimens using the stereomicroscope. ESEM evaluation was done for resin dentin interfaces for all types of adhesives.Results: There was a statistically significant effect of dentin substrate, while the adhesive system type was not. One way ANOVA followed by Tukey HSD post hoc test showed that, the remineralized dentin recorded the highest micro shear bond strength value with Single Bond Universal followed by Futurabond M+. The artificial caries affected dentin showed the highest micro shear bond strength value with Solobond M followed by Futurabond DC, which also recorded the lowest micro shear bond strength result with remineralized dentin.Conclusions: 1- Performance of the tested adhesives strategies was shown to be dentin-dependant.2- Dentin pretreatment with CPP-ACPF containing paste affects positively the micro-shear bond strength of Single bond universal and Futurabond M+ universal adhesives when used in self-etch mode.3-The specific chemical formula of the tested resin adhesives might coordinate with the demineralized dentin.

Signaling Molecules and Pulp Regeneration

Signaling molecules play an essential role in tissue engineering because they regulate regenerative processes. Evidence exists from animal studies that single molecules such as members of the transforming growth factor beta superfamily and factors that induce the growth of blood vessels (vascular endothelial growth factor), nerves (brain-derived neurotrophic factor), or fibroblasts (fibroblast growth factor) may induce reparative dentin formation. Mainly the formation of atubular dentin (osteodentin) has been described after the application of single molecules or combinations of recombinant growth factors on healthy exposed pulps or in pulp regeneration. Generally, such preparations have not received regulatory approval on the market so far. Only the use of granulocyte colony-stimulating factors together with cell transplantation is presently tested clinically. Besides approaches with only 1 or few combined molecules, the exploitation of tissue-derived growth factors depicts a third promising way in dental pulp tissue engineering. Preparations such as platelet-rich plasma or platelet-rich fibrin provide a multitude of endogenous signaling molecules, and special regulatory approval for the market does not seem necessary. Furthermore, dentin is a perfect reservoir of signaling molecules that can be mobilized by treatment with demineralizing agents such as EDTA. This conditions the dentin surface and allows for contact differentiation of pulp stem cells into odontoblastlike cells, protects dentin from resorption, and enhances cell growth as well as attachment to dentin. By ultrasonic activation, signaling molecules can be further released from EDTA pretreated dentin into saline, thus avoiding cytotoxic EDTA in the final preparation. The use of dentin-derived growth factors offers a number of advantages because they are locally available and presumably are most fit to induce signaling processes in dental pulp. However, better characterization and standardization of the procedures are required.

Resin-dentin bond stability and physical characterization of a two-step self-etching adhesive system associated with TiF4

ObjectivesTo evaluate the bond strength to superficial (SD) and deep (DD) dentin after the use of 2.5% (T2.5%) or 4% (T4%) titanium tetrafluoride (TiF4) in aqueous solution as a dentin pretreatment, or when incorporated into the primer (T2.5%P and T4%P) of an adhesive system (Clearfil SE Bond/CL). Degree of conversion (DC), particle size (PS), polydispersity index (PI) and zeta potential (ZP) of the solutions were evaluated. MethodsFifty molars were sectioned longitudinally to obtain two slices of each tooth, which were demarcated into SD and DD. Treatments were applied (n=10): CL; T2.5%; T4%; T2.5%P; T4%P. After 24h or 180days storage, microshear bond strength tests were performed. The DC values of T2.5%P and T4%P were evaluated by FTIR. PS, PI and ZP were measured using dynamic light scattering. ResultsAnalysis of mixed models showed significant effect of concentration of TiF4 * solution * storage time (p=0.0075). There were higher bond strength values in SD than in DD (p=0.0105) for all treatments in both times. The failure mode showed adhesive failures in the majority of groups, irrespective of depth and time (p=0.3746). The bond strength values were not affected by treatments. Lower average particle size was observed for T2.5%P and T4%P at baseline. T2.5% and T4% showed a trend towards agglomeration. SignificanceHigher bond strength values were achieved at SD for all treatments and times. The failure modes observed were adhesive. TiF4 incorporation did not affect DC. T2.5%P and T4%P presented excellent stability over time.

Titanium tetrafluoride incorporated into a two-step self-etching adhesive system: physico-mechanical characterization and bonding stability.

To evaluate the influence of TiF4 incorporated into the primer (P) or bond (B) of a self-etching adhesive system on long-term dentin bonding, and evaluate the physico-mechanical properties of TiF4-containing adhesives. Dentin surfaces received the following treatments (n = 8): CL (Clearfil SE Bond); TiF4CL (dentin pretreatment with TiF4 aqueous solution + CL); TiF4P (TiF4 incorporated into the P); TiF4B (TiF4 incorporated into the B). Microtensile bond strength (µTBS) and failure mode evaluations were performed after 24h, 6 months and one year, respectively. Degree of conversion (DC) and flexural strength (FS) were evaluated to determine whether TiF4 influenced adhesive properties. Particle size (PS), polydispersity index (PI) and zeta potential (ZP) of TiF4-containing adhesives were measured using dynamic light scattering. Two-way ANOVA for repeated measures was applied to µTBS data, and one-way ANOVA and Tukey tests to DC and FS results. There was no difference in µTBS among the groups (p = 0.818) regardless of time; the µTBS in each group was not significantly affected over time (p = 0.061). TiF4P and TiF4B significantly affected FS (p = 0.004). The DC for TiF4P was not significantly different from that of CL, and higher than that of TiF4B. Lower average particle size was observed for TiF4P at baseline. TiF4 aqueous solution showed a tendency to agglomerate. TiF4-containing adhesives did not influence µTBS or failure mode to dentin over time, although FS and DC were affected, especially when TiF4 was incorporated into the B. TiF4P presented excellent stability over time.

Role of dentin cross-linking agents in optimizing dentin bond durability

The present work compared the effects of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC-HCl) and ultraviolet (UV)- or blue light-activated riboflavin cross-linking agents on resin–dentin micro-tensile bond strength and nanoleakage in bonds produced using a two-step, etch-and-rinse adhesive after three storage intervals (24 h, 6 months, and 12 months). Forty eight extracted human third molars were used to investigate micro-tensile bond strength and interfacial nanoleakage in resin–dentin bonds created using Adper Single Bond 2, with or without pretreatment of acid-etched dentin surfaces. Either 0.5 M EDC-HCl or 1% riboflavin-5-phosphate activated by blue or UV light were used as cross-linking agents. Samples were evaluated after storage for 24 h, 6 months, or 12 months in distilled water at 37 °C. Statistical analyses revealed that 12 months of storage resulted in significant decreases in the bond strength of the controls (p < 0.003), with significant increases in their silver nanoleakage (p < 0.05), compared with the groups subjected to dentin pretreatment with either EDC-HCl or light-activated 1% riboflavin. Despite the significant drop in bond strength after 6 months’ storage in all experimental groups compared with the 24-h bond strength (p < 0.05), there was a further non-significant drop in bond strength after 12 months in samples treated with EDC-HCl and UV-activated 1% riboflavin (p > 0.05). Dental collagen cross-linking induced by UV- or blue light-activated 1% riboflavin or EDC-HCl enhanced the durability and strength of the resin–dentin bond.

Effect of pH on dentin protease inactivation by carbodiimide.

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 (1×2×6mm) were divided into six groups (n=8 per group). Then, EDC (0.3M) was solubilized in distilled water with pH of 2, 4, 6, 7, 9, or 11. Control EDC was solubilized in 0.1M 2-(N-morpholino) ethanesulfonic acid (MES) buffer and its pH was adjusted to 6. The dentin beams were pretreated for 1min with EDC at each pH or with EDC in MES buffer at pH6.0 and then incubated in 1ml of simulated body fluid (pH7.2) for 1, 3, 7, or 14d. 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.

Effect of dentin pretreatment with potassium oxalate: A 6-year follow-up.

Oxalate-based products are effective against dentine sensitivity and have been studied as an option to improve long-term adhesive bonding strength. Our aim was to evaluate the effect of potassium oxalate on the microtensile bond strength (µTBS) of the dentin/resin interface after 24h, 1, and 6years. Dentin on the occlusal surface of 16 human premolars was exposed and etched with 35% phosphoric acid. The teeth were divided into four groups. Two groups received 3% monohydrated potassium oxalate and the following adhesive systems and composites: Adper Scotchbond Multipurpose+FiltekZ350 (3M/ESPE) and Prime & Bond NT+Esthet-X (Dentsply). Two control groups did not receive potassium oxalate. Teeth were cut into sticks and kept in distilled water at 37°C for 24h, 1, and 6years. The sticks underwent µTBS testing after storage. ANOVA, Tukey's post hoc test, and paired t test were used to compare storage times (α=0.05). The fracture mode of the specimens was classified under a stereomicroscope (40×). Morphology of the hybrid layer and the fracture pattern were observed with scanning electronic microscopy (SEM). Mean µTBS was high at 24h and decreased after 1 and 6years. After 6years, the mean µTBS values were similar with no statistically significant difference between the groups (p=.121). SEM images showed proper dentin hybridization. Dentin pretreatment with potassium oxalate did not affect hybrid layer formation, but bond strength decreased over time after 24h. Therefore, the clinical use of potassium oxalate to increase dentin bond durability is not indicated.

Effect of grape seed extract on the bond strength and durability of resin-dentin interface

To investigate the effect of grape seed extract (GSE) on the bond strength and durability of the resin-dentin interface using a two-step etch-and-rinse (E&R) and a universal adhesive (UA) system. Additionally the effect of dry and wet bonding on the interface created by UA was evaluated. The effect of GSE on the morphology, nanoleakage expression (NE) and bond strength of the resin-dentin interface was evaluated by scanning electron microscopy (SEM) evaluation, interfacial NE and micro-tensile bond strength (μ-TBS) testing respectively. Dentin surfaces of sound molars were exposed, acid-etched, and treated with cross-linking pre-conditioners followed by application of adhesive, light-cured, and built up with restorative composite in an incremental manner. After the restored teeth were left for 24 h in distilled water for polymerisation, dentin beams were sectioned for μ-TBS testing and dentin slabs for SEM and NE. Pre-treatment with GSE did not significantly alter the μ-TBS and NE of any adhesives compared to their respective controls at 24 h and 1 year. Significant decrease in μ-TBS and significant increase in NE after 1 year of storage compared to 24 h results is observed. SEM evaluation showed good hybrid layer formation at 24 h but shows a degraded appearance after 1 year especially with wet bonding technique. Pre-treatment of acid-etched dentin with 6.5% GSE w/v for 1 min, before the application of the adhesive did not significantly improve the bond strength and durability of the resin-dentin interface created by the two-step E&R adhesive and UA. Dry bonding technique for UA seemed more effective.

Long-term bond strength of a self-adhesive resin cement to intraradicular dentin pretreated with chlorhexidine and ethanol

Abstract Introduction Self-adhesive resin cements do not require prior preparation of the tooth surface, therefore dentin pretreatments may influence long-term bond strength. Objective To evaluate the influence of 100% ethanol (ET) and 2% chlorhexidine (CL) treatment of intraradicular dentin on the long-term bond strength (BS) of a self-adhesive resin cement (SRC). Material and method 80 bovine roots were restored with fiber posts and SRC (U200 3M/ESPE) and distributed into 4 groups according to dentin treatment: Group 1 – without treatment; Group 2 – 2% CL for 1 minute; Group 3 – 100% ET for 1 minute; Group 4 – 2% CL, followed by 100% ET. The samples were cross-sectioned to obtain two sections (0.7 mm) thick for each root third: coronal, middle and apical. The immediate push-out test was carried out after 48 hours, and the long-term push-out test, after 180 days. Result The three-way ANOVA test for randomized blocks showed no difference between the BS values at 48 hours and 80 days, irrespective of the treatment and the third (p&gt;0.05). The interaction of the treatment/third pairing was significant (p = 0.041) since the treatment with CL promoted lower BS in the coronal third, while treatment with ET promoted better BS in the apical third. Conclusion Treatment with CL and ET, separately or combined, promoted no differences between the BS values of the SRC to root dentin over time.

Effect of a novel quaternary ammonium silane on dentin protease activities

ObjectivesDemineralized dentin collagen release C-terminal cross-linked telopeptide (ICTP) and C-terminal peptide (CTX) during degradation. The present study evaluated the effects of dentin pre-treatment with K21, a quaternary ammonium silane (QAS), on matrix metalloproteinase (MMP) and cathepsin K-mediated collagen degradation. MethodsDentin beams were demineralized with 10% H3PO4 for 24h. After baseline dry mass measurements, the beams were divided into 5 groups (N=10) according to protease inhibitors. The beams were pre-treated for 2min with 2% chlorhexidine (CHX), 2%, 5% or 10% QAS; no pre-treatment was performed for the control group. The beams were subsequently incubated in calcium- and zinc-containing medium for 3, 7 or 14days, after which changes in dry mass were measured and incubation media were examined for ICTP and CTX release. The MMP-2 and cathepsin K activities in QAS-treated dentin powder were also quantified using ELISA. ResultsThe two factors (disinfectants and time) had a significant effect on dry mass loss, ICTP and CTX release (p<0.001). The percentage of dry mass loss increased with time and was significantly lower in all experimental groups when compared to the control at 14days (p<0.001). Conversely, the rate of ICTP and CTX release was significantly lower in the experimental groups, compared to the uninhibited control at 7 and 14days (p<0.001). Dentinal MMP-2 and cathepsin K activities were significantly reduced after demineralized dentin was pre-treated with QAS. ConclusionThe experimental QAS is a good inhibitor of MMP and cathepsin K activities in demineralized dentin. Clinical significanceThe newly developed antibacterial quaternary ammonium silane increases the resistance of dentin collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The quaternary ammonium silane cavity disinfectant is promising for use as a protease inhibitor to improve durability of resin-dentin bonds.

Influence of dentin pretreatment on bond strength of universal adhesives

Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application.Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Premio BOND, Peak Universal Bond. The adhesive systems were applied following each manufacturer’s instructions. The teeth were randomly assigned to three different dentin surface pretreatments: no pretreatment agent (control), 37% phosphoric acid etching, glycine pretreatment. The specimens were placed in a universal testing machine in order to measure and compare bond strength values.Results: The Kruskal–Wallis analysis of variance and the Mann–Whitney test were applied to assess significant differences among the groups. Dentin pretreatments provided different bond strength values for the adhesives tested, while similar values were registered in groups without dentin pretreatment.Conclusions: In the present report, dentin surface pretreatment did not provide significant differences in shear bond strength values of almost all groups. Acid pretreatment lowered bond strength values of Futurabond and Peak Universal Adhesives, whereas glycine pretreatment increased bond strength values of G Praemio Bond adhesive system.

Effectiveness of sodium hypochlorite and sulfinic acid sodium salt treatment on dentin-resin bonding: Long-term durability of one-step self-etching adhesive.

This study aimed to evaluate the effect of sulfinic acid sodium salt interposition after acid and sodium hypochlorite treatment (NC treatment) on dentin bonding durability using a mild type one-step self-etching adhesive. Fifteen human third molars were randomly assigned into three experimental groups according to dentin pretreatment before applying the one-step self-etching adhesive: Cont group, without pretreatment; NC group, pretreatment with phosphoric acid and sodium hypochlorite gel; and NC+AC group, additional treatment with sulfinic acid sodium salt followed by the same pretreatment of the NC group. Microtensile bond strength was measured and the pre-treated dentin surface, fracture modes, and bonding interface were observed. The bond strength of the NC+AC group was significantly higher than that of the other groups (p<0.001). The dentin-adhesive interface was degraded after 1 year only in the Cont group. Our results demonstrated NC treatment improves bonding durability and application of sodium sulfinic acid salt after NC treatment improves bonding effectiveness.

Effect of Application of Silver Diamine Flouride/ Potassium Ioded Agent Following two different Dentine Pre-treatment Methods on The Microshear Bond Strength and Micromorphology of RMGIC/ Dentine Interface.

Effect of Application of Silver Diamine Flouride/ Potassium Ioded Agent Following two different Dentine Pre-treatment Methods on The Microshear Bond Strength and Micromorphology of RMGIC/ Dentine Interface.

Sodium Hypochlorite as Fluorotic Dentin Pretreatment of Two-Step Self-Etch Adhesive with Silver Nanoparticle: Atomic Force Microscope and Adhesive Microtensile Bond Strength Evaluation

The objective of this work was to evaluate the effect of pretreatment with commercial sodium hypochlorite, 5.25%, with a self-etch adhesive (Optibond Versa) in its original formula and with the incorporation of silver nanoparticles (NaAg) on fluorotic dentin. 240 human molars were classified according to fluorosis severity with Thylstrup-Fejerskov Index (TFI) and subdivided into three study subgroups according to the adhesive technique: (1) self-etch (SE) control subgroup; (2) NaOCl/SE subgroup; (3) NaOCl/SE + NaAg subgroup. The nanostructural characteristics were observed by AFM, μTBS was tested, and hybrid layer formation was observed by SEM. One-way analyses of variance (ANOVA) and Tukey-Kramer post hoc tests were used. No statistically significant differences were found in roughness values in any of the subgroups and subgroups studied. Remnants of smear layer were detected in areas devoid of resin tags in SEM images of samples bonded with subgroup 2, in contrast to subgroup 3. No statistically significant difference between any of the results was found in μTBS and a greater number of adhesive failures were observed. The results show that the pretreatment technique of 5.25% NaOCl and the incorporation of NaAg to the self-adhesive system do not produce a surface more adequate for a better adhesion.

Effect of epigallocatechin gallate, green tea extract and chlorhexidine application on long-term bond strength of self-etch adhesive to dentin

This study evaluated the effect of dentin pretreatment with metalloproteinase inhibitors on long-term microtensile bond strength (μTBS) of self-etch adhesive (SEA) to dentin. Thirty-two dentin fragments received pretreatments (n=8): C: control (not treated); GT: 2% green tea extract; CLX: 2% chlorhexidine; EGCG: 2% epigallocatechin gallate. SEAs (Clearfil SE Bond) and resin composite were applied to dentin surface. After 24h, resin-blocks were cut into sticks submitted to μTBS testing immediately or after 6 months of storage in water. Two-way ANOVA and Tukey test (α=5%) indicated that CLX group showed μTBS values statistically superior to the other groups at immediate testing, whereas those of EGCG group were the lowest (p=0.018). After 6 months, a significant increase in μTBS values was observed for all groups, except for CLX (p=0.018). In conclusion, μTBS increased in dentin pretreatment with EGCG and green tea groups, and in the non-treated group.

Influence of dentin pretreatment with synthetic hydroxyapatite application on the bond strength of fiber posts luted with 10‐methacryloyloxydecyl dihydrogen phosphate‐containing luting systems

The aim of this in vitro study was evaluate the effect of application of synthetic hydroxyapatite on fiber post bond strength to radicular dentine. Forty, single-root teeth were endodontically treated and an 8 mm post space was prepared. Specimens were randomly placed in four groups (n = 10 in each) and treated using the following fiber post luting procedures: group 1, 17% EDTA + Panavia SA; group 2, 17% EDTA + Teethmate Desensitizer + Panavia SA; group 3, All-Bond Universal + Duo-Link Universal; and group 4, All-Bond Universal + Teethmate Desensitizer + Duo-Link Universal. Fiber posts were luted in the post space and light-cured for 120 s using a light-emitting diode (LED) lamp. After 7 d of storage at 37°C, the teeth were cut into 1-mm-thick slices, which were subjected to a push-out test until failure using a universal testing machine. Two specimens per group were prepared for scanning electron microscopy analysis. An energy-dispersive X-ray spectroscopy detector was used for elemental analysis of the specimen surface. The results were statistically analyzed using one-way anova. The fiber post bond strength was statistically significantly increased after the application of Teethmate Desensitizer to post space walls, either with a 10-MDP-containing self-adhesive cement or with a universal adhesive. Scanning electron microscopy and EDAX analysis showed that Teethmate Desensitizer created a calcium phosphate precipitate over post space dentinal tubules, which significantly improved the bond strength of the fiber post luted with 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing adhesive systems.