RESUMEN
PURPOSE: To evaluate the effect of application time and viscosity of meta-phosphoric acid (MPA) and ortho-phosphoric acid (OPA) on the push-out resin-dentin bond strength (PBS) and nanoleakage (NL) at the adhesive-root dentin interface. METHODS AND MATERIALS: Ninety-six roots of premolars were endodontically prepared and randomly assigned into groups according to the (i) acid (OPA and MPA), (ii) viscosity (gel and liquid), and (iii) application time (7 and 15 seconds). Fiber posts were cemented to the roots, which were then transversally sectioned into serial slices. The slices (cervical, medium, and apical) were subjected to PBS or NL. Analysis of the dentin etching pattern was performed using scanning electron microscopy (SEM). The PBS (MPa) and NL (%) data were subjected to three-way repeated-measures analysis of variance (ANOVA) and Tukey's test (α=0.05). RESULTS: The cross-product interaction was significant for both PBS and NL (p<0.001). No significant difference in the PBS was observed with the use of OPA compared to MPA (p>0.05). Higher PBS values were observed in the groups etched for 15 seconds compared to 7 seconds, regardless of the acid, viscosity, or root third (p<0.05). Lower NL was observed for MPA etching when compared to OPA etching (p<0.05), and these values were not affected by increasing the application time or acid viscosity (p>0.05). A more pronounced etching pattern was observed with OPA than MPA regardless of the acid viscosity. CONCLUSION: The use of 40% meta-phosphoric acid promoted adequate bond strength without increasing dentin demineralization or void spaces in the hybrid layer.
Asunto(s)
Recubrimiento Dental Adhesivo , Técnica de Perno Muñón , Cavidad Pulpar , Dentina , Recubrimientos Dentinarios/química , Ensayo de Materiales , Ácidos Fosfóricos/farmacología , Cementos de Resina/química , ViscosidadRESUMEN
This study evaluated the influence of new monomers derived from cashew nut shell liquid (CNSL) applied for dentin biomodification on resin-dentin bond strength, nanoleakage, and micropermeability to sound and artificially-created caries-affected dentin. Human dentin specimens were assigned to five groups, according to the following dentin pretreatment solutions: Absolute ethanol (control), 2 wt% grape seed extract (Vitis vinifera), 2 wt% cardol [from cashew nut shell liquid (CNSL)], 2 wt% cardol-methacrylate or 2 wt% cardanol-methacrylate applied on sound and artificial caries-affected dentin. Specimens were analyzed after 24 hour or 1 year of water storage. Microtensile bond strength (µTBS) (n=6), interface micropermeability (n=3), and silver nanoleakage (n=6) were assessed using a universal testing machine, confocal laser scanning microscope, and scanning electron microscope, respectively. In sound dentin, no difference in bond strength was observed between the groups in either storage period. In artificial caries-affected dentin, pretreatment with cardol-methacrylate resulted in statistically higher bond strength than all the other treatments in both storage periods. Cardol-methacrylate treatment resulted in less nanoleakage, along with improved interfacial integrity, compared to further treatments in artificial caries-affected dentin. Regarding micropermeability analysis, all treatments depicted deficient sealing ability when applied on artificial caries-affected dentin, with the presence of gaps in the control group. In conclusion, cardol-methacrylate is a promising plant-derived monomer to reinforce the hybrid layer, since it preserved resin-dentin bond strength and improved dentin bonding, especially to caries-affected dentin, a well-known harsh substrate for adhesion longevity.
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Recubrimiento Dental Adhesivo , Caries Dental , Recubrimiento Dental Adhesivo/métodos , Caries Dental/terapia , Susceptibilidad a Caries Dentarias , Dentina , Recubrimientos Dentinarios/química , Recubrimientos Dentinarios/uso terapéutico , Humanos , Ensayo de Materiales , Metacrilatos , Cementos de Resina/química , Resistencia a la TracciónRESUMEN
The aim of this study was to evaluate the influence of nanofiller particles in simplified universal adhesive on the long-term microtensile bond strength and silver nitrate up-take, as well as water sorption and solubility. Commercial adhesives Ambar Universal (FGM) in nanofilled-containing version (filled) and same lot without fillers (unfilled) were donated and applied by means of etch-and-rinse strategy. Microtensile bond strength was surveyed after 24-hours or 1-year water storage. Silver nitrate uptake was assayed using scanning electron microscopy (SEM). Water sorption and solubility experiments were performed based on ISO 4049:2009. Statistical analysis was performed using two-way ANOVA and Tukey test (p<0.05). The bond strength of both the adhesives were statistically similar at 24 hours (p>0.05), but the filled group attained significant bond strength reduction after aging when compared to initial bond strength (p<0.001). Conversely, unfilled adhesive presented stable adhesion after 1-year storage (p=0.262). Silver nitrate uptake was similar for both adhesives, with little silver impregnation at the hybrid and adhesive layers. Water sorption was higher with filled adhesive compared to the unfilled one (p=0.01). Conversely, solubility was higher in unfilled in comparison to filled one (p=0.008). The presence of nanofillers in universal adhesive achieves higher water sorption and dentin bond degradation, which did not occur in the unfilled adhesive.
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Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Adhesivos/análisis , Cementos Dentales/química , Dentina/química , Recubrimientos Dentinarios/química , Ensayo de Materiales , Nitrato de Plata/análisis , Solubilidad , Resistencia a la Tracción , AguaRESUMEN
OBJECTIVE: To investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (µTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive. METHODS: Experimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15s etching to detect collagen cross-linking. Extracted third molars were used for µTBS (n=7) and fracture mode analysis of Optibond S (Kerr), tested after 24h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey's test (p<0.05). RESULTS: FTIR confirmed cross-linking for all agents. µTBS of CC was the highest (46.6±6.2MPa), but reduced significantly after aging (35.7±5.2MPa) (p<0.001). LIG (30.6±3.7MPa) and CARD (28.3±1.8MPa) attained similar µTBS which were stable after aging (p>0.05). Fracture mode was predominantly adhesive. At 24h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer. SIGNIFICANCE: Altogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.
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Recubrimiento Dental Adhesivo , Filtración Dental , Colágeno , Cementos Dentales , Dentina , Recubrimientos Dentinarios , Humanos , Ensayo de Materiales , Ácidos Fosfóricos , Cementos de Resina , Resistencia a la TracciónRESUMEN
OBJECTIVES: Dental resins filled with hydroxyapatite (HAp) nanoparticles have significantly revolutionized restorative dentistry offering advantages such as remineralization potential and increase of polymerization. However, these materials have limited radiopacity hindering the diagnosis of secondary caries. The present study investigated the development of a new radiopaque dental adhesive by incorporating novel pure strontium hydroxyapatite nanoparticles [Sr10(PO4)6(OH)2, SrHAp] synthesized by a simple hydrothermal method. METHODS: Strontium phosphates were prepared using co-precipitation (SrHAp0h) and hydrothermal treatment for 2 and 5h (SrHAp2h and SrHAp5h). The crystallinity, crystallite size, textural and morphology features of the nanoparticles were characterized by XRD, FT-IR, micro-Raman and TEM. Strontium hydroxyapatite (SrHAp) or calcium hydroxyapatite (HAp) nanoparticles were then incorporated (10â¯wt%) into an adhesive resin of a commercial three-step etch-and-rinse adhesive to evaluate the radiopacity of disk-shaped specimens, degree of conversion (DC) assessed by FT-IR and mechanical properties by three-point bending test. The unfilled adhesive was used as negative control. RESULTS: While SrHAp0h and SrHAp2h resulted a phase mixing, the pure and highly crystalline phase of strontium hydroxyapatite free of calcium was obtained with 5h hydrothermal treatment (SrHAp5h). The TEM images revealed nanorods morphology for SrHAp5h. SrHAps incorporated into adhesive showed higher radiopacity, no alteration on DC despite slightly reducing the mechanical properties. SIGNIFICANCE: Although the mechanical properties are slightly impaired, incorporation of SrHAp nanoparticles offers potential method to improve radiopacity of restorative dental resins, easing the tracking of actual remineralization effects and enabling diagnosis of recurrent caries.
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Cementos Dentales/química , Hidroxiapatitas/química , Fenómenos Mecánicos , Nanoestructuras/química , Estroncio/química , Precipitación Química , Pruebas MecánicasRESUMEN
OBJECTIVES: Hydroxyethyl-methacrylate (HEMA) is still widely used in simplified adhesives. Indeed, several shortcomings occur with this monomer, such as water uptake and formation of linear polymers. This study aimed to compare the effects of HEMA replacement by glycerol-dimethacrylate (GDMA) on selected physicochemical properties and bonding performance of simplified model adhesives. MATERIALS AND METHODS: Experimental simplified etch-and-rinse and self-etch adhesives were formulated containing 20â¯wt% HEMA or GDMA. Three-point bending test was used to obtain the elastic modulus of bar-shaped specimens, and water sorption and solubility were attained by ISO-4049 (ISO, 2009) method. Degree of conversion was surveyed by Micro-Raman spectroscopy, and microtensile bond strength was tested after 24â¯h or 6 months simulated pulpal pressure aging. Statistical analysis was realized with two-way ANOVA and Tukey's test (pâ¯<â¯0.05). RESULTS: GDMA promoted higher elastic modulus to the self-etch adhesive, and GDMA-containing etch-and-rinse adhesive achieved overall lower water sorption and solubility. The degree of conversion was statistically higher for GDMA adhesives than for HEMA etch-and-rinse one. All bond strengths dropped significantly after aging, except that of GDMA self-etch adhesive. The nanoleakage was higher and gaps were found in the interface of HEMA-containing adhesives, which were less present in GDMA equivalents. CONCLUSIONS: GDMA is a feasible hydrophilic dimethacrylate monomer to replace HEMA in simplified adhesives, thereby providing better polymerization, mechanical properties and dentin adhesion as well as lower water uptake and solubility.
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Adhesivos/química , Glicerol/química , Interacciones Hidrofóbicas e Hidrofílicas , Metacrilatos/química , Resistencia a la TracciónRESUMEN
OBJECTIVES: Several polyphenols from renewable sources were surveyed for dentin biomodification. However, phenols from cashew nut shell liquid (CNSL, Anacardium occidentale) and from Aroeira (Myracrodruon urundeuva) extract have never been evaluated. The present investigation aimed to compare the dentin collagen crosslinking (biomodification) effectiveness of polyphenols from Aroeira stem bark extract, proanthocyanidins (PACs) from grape-seed extract (Vitis vinifera), cardol and cardanol from CNSL after clinically relevant treatment for one minute. METHODS: Three-point bending test was used to obtain the elastic modulus of fully demineralized dentin beams before and after biomodification, whilst color change and mass variation were evaluated after four weeks water biodegradation. Color aspect was assessed by optical images after biodegradation whereas collagen cross-linking was investigated by micro-Raman spectroscopy. Statistical analysis was performed with repeated-measures two way ANOVA and Tukey's test (p<0.05). RESULTS: The increase in elastic modulus after biomodification was in the order cardol>cardanol>aroeira=PACs with cardol solution achieving mean 338.2% increase. The mass increase after biomodification followed the same order aforementioned. Nevertheless, after four weeks aging, more hydrophobic agent (cardanol) induced the highest resistance against water biodegradation. Aroeira and cardol attained intermediate outcomes whereas PACs provided the lower resistance. Tannin-based agents (Aroeira and PACs) stained the specimens in dark brown color. No color alteration was observed with cardol and cardanol treatments. All four agents achieved crosslinking in micro-Raman after one minute application. SIGNIFICANCE: In conclusion, major components of CNSL yield overall best dentin biomodification outcomes when applied for one minute without staining the dentin collagen.
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Anacardiaceae , Colágeno/metabolismo , Extracto de Semillas de Uva/farmacología , Dentina , Humanos , ProantocianidinasRESUMEN
OBJECTIVES: Enamel resin infiltrants are biomaterials able to treat enamel caries at early stages. Nevertheless, they cannot prevent further demineralization of mineral-depleted enamel. Therefore, the aim of this work was to synthesize and incorporate specific hydroxyapatite nanoparticles (HAps) into the resin infiltrant to overcome this issue. METHODS: HAps were prepared using a hydrothermal method (0h, 2h and 5h). The crystallinity, crystallite size and morphology of the nanoparticles were characterized through XRD, FT-IR and TEM. HAps were then incorporated (10wt%) into a light-curing co-monomer resin blend (control) to create different resin-based enamel infiltrants (HAp-0h, HAp-2h and HAp-5h), whose degree of conversion (DC) was assessed by FT-IR. Enamel caries lesions were first artificially created in extracted human molars and infiltrated using the tested resin infiltrants. Specimens were submitted to pH-cycling to simulate recurrent caries. Knoop microhardness of resin-infiltrated underlying and surrounding enamel was analyzed before and after pH challenge. RESULTS: Whilst HAp-0h resulted amorphous, HAp-2h and HAp-5h presented nanorod morphology and higher crystallinity. Resin infiltration doped with HAp-2h and HAp-5h caused higher enamel resistance against demineralization compared to control HAp-free and HAp-0h infiltration. The inclusion of more crystalline HAp nanorods (HAp-2h and HAp-5h) increased significantly (p<0.05) the DC. SIGNIFICANCE: Incorporation of more crystalline HAp nanorods into enamel resin infiltrants may be a feasible method to improve the overall performance in the prevention of recurrent demineralization (e.g. caries lesion) in resin-infiltrated enamel.
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Esmalte Dental , Durapatita , Nanotubos , Cementos de Resina , Luces de Curación Dental , Humanos , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
The number of carbon atoms and/or ester/polyether groups in spacer chains may influence the interaction of functional monomers with calcium and dentin. The present study assessed the chemical interaction and bond strength of 5 standard-synthesized phosphoric-acid ester functional monomers with different spacer chain characteristics, by atomic absorption spectroscopy (AAS), ATR-FTIR, thin-film x-ray diffraction (TF-XRD), scanning electron microscopy (SEM), and microtensile bond strength (µTBS). The tested functional monomers were 2-MEP (two-carbon spacer chain), 10-MDP (10-carbon), 12-MDDP (12-carbon), MTEP (more hydrophilic polyether spacer chain), and CAP-P (intermediate hydrophilicity ester spacer). The intensity of monomer-calcium salt formation measured by AAS differed in the order of 12-MDDP=10-MDP>CAP-P>MTEP>2-MEP. FTIR and SEM analyses of monomer-treated dentin surfaces showed resistance to rinsing for all monomer-dentin bonds, except with 2-MEP. TF-XRD confirmed the weaker interaction of 2-MEP. Highest µTBS was observed for 12-MDDP and 10-MDP. A shorter spacer chain (2-MEP) of phosphate functional monomers induced formation of unstable monomer-calcium salts, and lower chemical interaction and dentin bond strength. The presence of ester or ether groups within longer spacer carbon chains (CAP-P and MTEP) may affect the hydrophilicity, µTBS, and also the formation of monomer-calcium salts.
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Recubrimiento Dental Adhesivo , Metacrilatos/química , Cementos de Resina/química , Calcio/química , Carbono/química , Resinas Compuestas/química , Dentina/ultraestructura , Compuestos Epoxi , Resinas Epoxi/química , Alcoholes Grasos/química , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Organofosfatos/química , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Espectrofotometría Atómica , Espectroscopía Infrarroja por Transformada de Fourier , Estrés Mecánico , Propiedades de Superficie , Resistencia a la Tracción , Difracción de Rayos XRESUMEN
AIM: To evaluate the effects of two methods to simulate physiological pulpal pressure on the dentine bonding performance of two all-in-one adhesives and a two-step self-etch silorane-based adhesive by means of microtensile bond strength (µTBS) and nanoleakage surveys. METHODOLOGY: The self-etch adhesives [G-Bond Plus (GB), Adper Easy Bond (EB) and silorane adhesive (SIL)] were applied to flat deep dentine surfaces from extracted human molars. The restorations were constructed using resin composites Filtek Silorane or Filtek Z350 (3M ESPE). After 24 h using the two methods of simulated pulpal pressure or no pulpal pressure (control groups), the bonded teeth were cut into specimens and submitted to µTBS and silver uptake examination. Results were analysed with two-way anova and Tukey's test (P < 0.05). RESULTS: Both methods of simulated pulpal pressure led statistically similar µTBS for all adhesives. No difference between control and pulpal pressure groups was found for SIL and GB. EB led significant drop (P = 0.002) in bond strength under pulpal pressure. Silver impregnation was increased after both methods of simulated pulpal pressure for all adhesives, and it was similar between the simulated pulpal pressure methods. CONCLUSIONS: The innovative method to simulate pulpal pressure behaved similarly to the classic one and could be used as an alternative. The HEMA-free one-step and the two-step self-etch adhesives had acceptable resistance against pulpal pressure, unlike the HEMA-rich adhesive.