RESUMEN
We evaluated the effects of preliminary etching of dentine on the stability of the bond created by one-step self-etch adhesives under different storage conditions. Adper Easy Bond (3M ESPE) and iBond Self-Etch (iBond SE; Heraeus Kulzer) were applied with an etch-and-rinse (i.e. after preliminary phosphoric acid etching for 15 s) or a self-etch approach. Resin-dentine bonded specimens were sectioned perpendicularly to the adhesive interface according to the 'non-trimming technique'. Beams were stored in artificial saliva for 24 h, 6 months, or 1 yr at 37°C, or in 10% NaOCl for 5 h at room temperature, and then stressed until failure; the microtensile bond strengths were calculated. Interfacial nanoleakage of additional teeth was evaluated using light microscopy or transmission electron microscopy. Adper Easy Bond showed higher bond strength than iBond SE, regardless of the dentine treatment. Similar microtensile bond strength results were obtained for teeth subjected to artificial ageing in 10% NaOCl for 5 h at room temperature and for teeth stored in artificial saliva for 6 months at 37°C. The additional etching step increased the microtensile bond strength for Adper Easy Bond and iBond SE. This study supports the use of one-step adhesives on etched dentine because of the increased bond strength compared with their application onto smear-layer-covered dentine, regardless of storage conditions.
Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Grabado Dental/métodos , Filtración Dental/prevención & control , Recubrimientos Dentinarios/uso terapéutico , Dentina/efectos de los fármacos , Calcificaciones de la Pulpa Dental , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Humanos , Cementos de Resina/uso terapéutico , Factores de TiempoRESUMEN
OBJECTIVES: The application of an electric field has been shown to positively influence the bonding of dentin bonding systems (DBS) by improving adhesive impregnation into dentin. However, the mechanism responsible for this phenomenon has not been completely elucidated. The aim of this study was to clarify the effects of pH, matrix ionic strength, and applied voltage on the migration of commonly used DBS monomers in a model matrix (agarose gel). METHODS: Some common monomers examined were bis-GMA (2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane); HEMA (2-hydroxyethyl methacrylate); 2-MP (bis[2-(methacryloyloxy) ethyl] phosphate); TCDM [di(hydroxyethyl methacrylate) ester of 5-(2,5,-dioxo tetrahydrofurfuryl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic acid]; and TEGDMA (triethylene glycol dimethacrylate). Agarose gels poured into a horizontal 10-well electrophoretic cell were used to mimic the collagen fibrils of the dentin organic matrix. The role of pH, matrix ionic strength, and voltage on monomer migration was assayed by modifying the experimental conditions. RESULTS: Results of experiments performed at pH 3.1, 6.3, 8.5, and 12.3; at low, medium, and high ionic strength; and at 50 and 100 V clearly showed that DBA monomer migration toward both the anode and the cathode can be affected by each of these parameters. SIGNIFICANCE: Migration of acrylic monomers toward the anode or cathode can be achieved as desired by selective choice of pH, ionic strength, and applied voltage. Additional studies are needed to evaluate the synergistic effects of DBS monomer blends on migration in an electric field.
Asunto(s)
Recubrimientos Dentinarios/química , Electroforesis en Gel de Agar , Bisfenol A Glicidil Metacrilato/química , Ácidos Carboxílicos/química , Permeabilidad de la Dentina , Electricidad , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Metacrilatos/química , Estructura Molecular , Concentración Osmolar , Polietilenglicoles/química , Ácidos Polimetacrílicos/químicaRESUMEN
OBJECTIVE: The function of endogenous MMP-3 and its distribution within the human dentine is unclear. Thus, the aim of the present study was to assay the presence and distribution of MMP-3 within human sound dentine by means of biochemical and immunohistochemical assays. METHODS: Powdered dentine from extracted human teeth was prepared and (1) partially demineralised with 1% H(3)PO(4) for 10min or (2) untreated (control). The presence of MMP-3 was measured using a colorimetric assay system (QuantiSir™, Epigentek, USA). Additional cryo-fractured dentine fragments were processed for immunohistochemical identification of MMP-3 under FEI-SEM. Casein-zymography was used to investigate MMP-3 activity. RESULTS: MMP-3 detected level was 2.732ng/µL in partially demineralised dentine powder, whilst it increased to 3.280ng/µL in mineralised dentine. The FEI-SEM analysis revealed positive immunolabelling patterns for MMP-3, predominantly localized on the intertubular collagen fibrillar network showing MMP-3 directly or indirectly bound to the collagen fibrils. Casein-zymograms showed positive proteolytic activity for MMP-3 in demineralised dentine powder. CONCLUSION: The results of the study clearly revealed the presence and distribution of MMP3 in human sound dentine. Whilst the presence was verified, its role is still unclear. Future studies are needed to investigate the possible involvement of MMP-3 in physiological and pathological condition of the dentine-pulp complex.
Asunto(s)
Dentina/enzimología , Metaloproteinasa 3 de la Matriz/análisis , Anticuerpos Monoclonales , Caseínas/análisis , Colágeno/análisis , Colágeno/ultraestructura , Colorimetría/métodos , Técnica de Descalcificación , Dentina/ultraestructura , Técnica de Fractura por Congelación , Humanos , Inmunohistoquímica , Microscopía Electrónica de RastreoRESUMEN
The aim of this study was to analyse the effect of preliminary phosphoric acid etching of enamel and dentine before the application of two, one-step self-etch adhesive systems. The systems were applied onto acid-etched or smear-layer-covered enamel and dentine. The treatment groups were as follows: group 1, Adper Easy Bond (3M ESPE) on etched substrate; group 2, Adper Easy Bond (control); group 3, iBond Self-Etch (Heraeus Kulzer) on etched substrate; and group 4, iBond Self-Etch (control). Enamel and dentine bond strengths were calculated using microshear and microtensile bond-strength tests. Additional specimens were prepared to evaluate nanoleakage at the dentine-adhesive interface and were investigated using light microscopy or transmission electron microscopy. Both adhesives demonstrated higher microshear bond strengths when enamel was pre-acid-etched with phosphoric acid (Adper Easy Bond 28.7 ± 4.8 MPa; iBond Self-Etch 19.7 ± 3.6 MPa) compared with controls (Adper Easy Bond 19.2 ± 3.3 MPa; iBond Self-Etch 17.5 ± 2.7 MPa) and increased microtensile bond strength when applied on acid-etched (Adper Easy Bond 35.8 ± 5.7 MPa; iBond Self-Etch 24.3 ± 7.9 MPa) vs. smear-layer-covered dentine (Adper Easy Bond 26.9 ± 6.2 MPa; iBond Self-Etch 17.6 ± 4.3 MPa). Adper Easy Bond showed lower nanoleakage than iBond Self-Etch, irrespective of preliminary etching. The results of this study support the use of phosphoric acid etching before the application of one-step self-etch adhesive systems.
Asunto(s)
Grabado Ácido Dental , Recubrimiento Dental Adhesivo , Filtración Dental , Cementos de Resina , Distribución de Chi-Cuadrado , Esmalte Dental/efectos de los fármacos , Análisis del Estrés Dental , Dentina/efectos de los fármacos , Humanos , Ácidos Fosfóricos/farmacología , Resistencia al Corte , Estadísticas no Paramétricas , Propiedades de Superficie , Resistencia a la TracciónRESUMEN
OBJECTIVE: Dentinal MMPs have been claimed to contribute to the auto-degradation of collagen fibrils within incompletely resin-infiltrated hybrid layers and their inhibition may, therefore, slow the degradation of hybrid layer. This study aimed to determine the contribution of a synthetic MMPs inhibitor (galardin) to the proteolytic activity of dentinal MMPs and to the morphological and mechanical features of hybrid layers after aging. METHODS: Dentin powder obtained from human molars was treated with galardin or chlorhexidine digluconate and zymographically analyzed. Microtensile bond strength was also evaluated in extracted human teeth. Exposed dentin was etched with 35% phosphoric acid and specimens were assigned to (1) pre-treatment with galardin as additional primer for 30s and (2) no pre-treatment. A two-step etch-and-rinse adhesive (Adper Scotchbond 1XT, 3M ESPE) was then applied in accordance with manufacturer's instructions and resin composite build-ups were created. Specimens were immediately tested for their microtensile bond strength or stored in artificial saliva for 12 months prior to being tested. Data were evaluated by two-way ANOVA and Tukey's tests (alpha=0.05). Additional specimens were prepared for interfacial nanoleakage analysis under light microscopy and TEM, quantified by two independent observers and statistically analyzed (chi(2) test, alpha=0.05). RESULTS: The inhibitory effect of galardin on dentinal MMPs was confirmed by zymographic analysis, as complete inhibition of both MMP-2 and -9 was observed. The use of galardin had no effect on immediate bond strength, while it significantly decreased bond degradation after 1 year (p<0.05). Interfacial nanoleakage expression after aging revealed reduced silver deposits in galardin-treated specimens compared to controls (p<0.05). CONCLUSIONS: This study confirmed that the proteolytic activity of dentinal MMPs was inhibited by the use of galardin in a therapeutic primer. Galardin also partially preserved the mechanical integrity of the hybrid layer created by a two-step etch-and-rinse adhesive after artificial aging.
Asunto(s)
Recubrimiento Dental Adhesivo , Dentina/efectos de los fármacos , Dipéptidos/farmacología , Inhibidores de la Metaloproteinasa de la Matriz , Inhibidores de Proteasas/farmacología , Grabado Ácido Dental , Antiinfecciosos Locales/farmacología , Bisfenol A Glicidil Metacrilato/química , Clorhexidina/análogos & derivados , Clorhexidina/farmacología , Resinas Compuestas/química , Filtración Dental/clasificación , Materiales Dentales/química , Dentina/enzimología , Dentina/ultraestructura , Dipéptidos/química , Humanos , Ensayo de Materiales , Metaloproteinasa 2 de la Matriz , Metacrilatos/química , Microscopía Electrónica de Transmisión , Ácidos Fosfóricos/química , Inhibidores de Proteasas/química , Cementos de Resina/química , Saliva Artificial/química , Tinción con Nitrato de Plata , Estrés Mecánico , Resistencia a la Tracción , Factores de TiempoRESUMEN
INTRODUCTION: This study examined the effect of different root canal irrigant agitation protocols in the penetration of an endodontic irrigant into dentinal tubules. METHODS: Fifty-six human single-rooted teeth were shaped with nickel-titanium instruments, and a final rinse of 5% sodium hypochlorite labeled with 0.2% alizarin red was performed. Specimens were assigned to 7 groups (N = 8) and submitted to the following rinse activation protocols: no agitation (control group), K-File or gutta-percha agitation, or different sonic (EndoActivator [Advanced Endodontics, Santa Barbara, CA] and Plastic Endo, Lincolnshire, IL) and ultrasonic (Satelec [Acteongroup, Merignac, France] and EMS, Nyon, Switzerland) agitations. Specimens were sectioned at 1, 3, and 5 mm from the apex in 1-mm-thick slabs, ground, and prepared for fluorescence microscopy at 100x with a wavelength of 450 milliseconds. Irrigant penetration into dentinal tubules was analyzed by using Kruskal-Wallis analysis of variance followed by post-hoc comparisons. RESULTS: Groups were ranked in the following order: control = K-file = gutta-percha < EndoActivator = Plastic Endo < Satelec = EMS. At 1 mm from the apex, the highest score was found for the EMS group compared with the control, K-file, gutta-percha, EndoActivator, and Plastic Endo groups, whereas no difference was found with the Satelec group. CONCLUSION: The results support the use of an ultrasonic agitation to increase the effectiveness of the final rinse procedure in the apical third of the canal walls.
Asunto(s)
Desbridamiento/métodos , Irrigantes del Conducto Radicular/química , Preparación del Conducto Radicular/métodos , Capa de Barro Dentinario , Irrigación Terapéutica/métodos , Ultrasonido , Análisis de Varianza , Humanos , Preparación del Conducto Radicular/instrumentación , Irrigación Terapéutica/instrumentaciónRESUMEN
OBJECTIVES: This study evaluated the role of endogenous dentin MMPs in auto-degradation of collagen fibrils within adhesive-bonded interfaces. The null hypotheses tested were that adhesive blends or chlorhexidine digluconate (CHX) application does not modify dentin MMPs activity and that CHX used as therapeutic primer does not improve the stability of adhesive interfaces over time. METHODS: Zymograms of protein extracts from human dentin powder incubated with Adper Scotchbond 1XT (SB1XT) on untreated or 0.2-2% CHX-treated dentin were obtained to assay dentin MMPs activity. Microtensile bond strength and interfacial nanoleakage expression of SB1XT bonded interfaces (with or without CHX pre-treatment for 30s on the etched surface) were analyzed immediately and after 2 years of storage in artificial saliva at 37 degrees C. RESULTS: Zymograms showed that application of SB1XT to human dentin powder increases MMP-2 activity, while CHX pre-treatment inhibited all dentin gelatinolytic activity, irrespective from the tested concentration. CHX significantly lowered the loss of bond strength and nanoleakage seen in acid-etched resin-bonded dentin artificially aged for 2 years. SIGNIFICANCE: The study demonstrates the active role of SB1XT in dentin MMP-2 activation and the efficacy of CHX inhibition of MMPs even if used at low concentration (0.2%).
Asunto(s)
Antiinfecciosos Locales/química , Clorhexidina/farmacología , Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Dentina/enzimología , Metaloproteinasa 2 de la Matriz/metabolismo , Análisis de Varianza , Antiinfecciosos Locales/uso terapéutico , Filtración Dental , Análisis del Estrés Dental , Permeabilidad de la Dentina , Recubrimientos Dentinarios/farmacología , Activación Enzimática , Humanos , Metaloproteinasa 2 de la Matriz/análisis , Inhibidores de la Metaloproteinasa de la Matriz , Cementos de Resina/farmacología , Estadísticas no Paramétricas , Resistencia a la TracciónRESUMEN
This study was performed to evaluate the effects of different in vitro ageing techniques on the dentine-bonded interface produced by a two-step etch-and-rinse adhesive. Composite build-ups were bonded to sectioned human molars using XP BOND and cut into non-trimmed dentine-composite beams for microtensile testing. Beams were assigned to one of the following storage conditions: (i) artificial saliva, 24 h (control); (ii) 10% sodium hypochlorite (NaOCl), 1 h; (iii) 10% NaOCl, 3 h; (iv) 60,000 thermal cycles, 2 months; (v) artificial saliva, 2 months; (vi) 60,000 thermal cycles, 6 months; and (vii) artificial saliva, 6 months. Beams were then pulled until failure and bond strength was calculated. Additional specimens were examined to investigate interfacial nanoleakage expression. NaOCl solution significantly reduced bonding compared with the control (group 2 = group 3 < group 1); and thermocycling reduced the bond strength in comparison to specimens stored for the same time-period in artificial saliva (group 4 < group 5; group 6 < group 7). Artificial ageing affected bond strength only after 6 months of storage (group 7 < group 5 = group 1). Increased nanoleakage was found under all ageing conditions in comparison with controls. NaOCl solution is a rapid and reliable in vitro ageing method for examining the durability of the adhesive interface produced by two-step etch-and-rinse adhesive systems.
Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Grabado Ácido Dental/métodos , Adhesividad , Filtración Dental/clasificación , Humanos , Ensayo de Materiales , Polímeros/química , Saliva Artificial/química , Hipoclorito de Sodio/química , Estrés Mecánico , Propiedades de Superficie , Temperatura , Resistencia a la Tracción , Factores de TiempoRESUMEN
PURPOSE: To evaluate microtensile bond strength and interfacial nanoleakage expression of adhesive interfaces created by XP-Bond on human deproteinized dentin immediately after bonding and after 6 months of artificial aging. MATERIALS AND METHODS: Noncarious human molars were selected, middle/deep dentin substrates were exposed, and either assigned to group 1 (XP-Bond applied on collagen-depleted dentin) or to group 2 (XP-Bond applied in accordance with manufacturers' instructions). In group 1, the etched dentin surface was treated with 10% NaOCl for 60 s to remove the exposed demineralized organic matrix before XP-Bond application. Composite/dentin beams were obtained in accordance with the microtensile nontrimming technique and either pulled to failure after 24 h or after 6 months' artificial aging. Data were analyzed with two-way ANOVA and Tukey's post-hoc test (p < 0.05). Interfacial nanoleakage evaluation was performed on additional adhesive interfaces to quantify the amount of silver tracer along the interface. RESULTS: The use of NaOCI before XP-Bond application (group 1: 18.9 +/- 5.8 MPa) reduced immediate bond strength by 62% compared to controls (group 2: 49.9 +/- 10.3 MPa; p < 0.5). After 6 months of artificial aging, the bond strength of groups 1 and 2 significantly decreased to 10.1 +/- 2.7 MPa and 35.2 +/- 8.7 MPa, resp (p < 0.05). Interfacial nanoleakage expression along XP-Bond adhesive interfaces was increased either by sodium hypochlorite or by artificial aging. CONCLUSION: The role of collagen fibrils is pivotal for the bonding of XP-Bond to dentin, as decreased immediate bond strength and reduced bond stability over time was found on collagen-depleted dentin.