RESUMEN
This study is aimed at evaluating the effects of triclosan-encapsulated halloysite nanotubes (HNT/TCN) on the physicochemical and microbiological properties of an experimental dental composite. A resin composite doped with HNT/TCN (8% w/w), a control resin composite without nanotubes (HNT/TCN-0%) and a commercial nanofilled resin (CN) were assessed for degree of conversion (DC), flexural strength (FS), flexural modulus (FM), polymerization stress (PS), dynamic thermomechanical (DMA) and thermogravimetric analysis (TGA). The antibacterial properties (M) were also evaluated using a 5-day biofilm assay (CFU/mL). Data was submitted to one-way ANOVA and Tukey tests. There was no significant statistical difference in DC, FM and RU between the tested composites (p > 0.05). The FS and CN values attained with the HNT/TCN composite were higher (p < 0.05) than those obtained with the HNT/TCN-0%. The DMA analysis showed significant differences in the TAN δ (p = 0.006) and Tg (p = 0) between the groups. TGA curves showed significant differences between the groups in terms of degradation (p = 0.046) and weight loss (p = 0.317). The addition of HNT/TCN induced higher PS, although no significant antimicrobial effect was observed (p = 0.977) between the groups for CFUs and (p = 0.557) dry weight. The incorporation of HNT/TCN showed improvements in physicochemical and mechanical properties of resin composites. Such material may represent an alternative choice for therapeutic restorative treatments, although no significance was found in terms of antibacterial properties. However, it is possible that current antibacterial tests, as the one used in this laboratory study, may not be totally appropriate for the evaluation of resin composites, unless accompanied with aging protocols (e.g., thermocycling and load cycling) that allow the release of therapeutic agents incorporated in such materials.
RESUMEN
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: The aim of this study was to investigate whether an electrical device for dental adhesive application (ElectroBond) influences bonding of two-step etch-and-rinse adhesives. MATERIALS AND METHODS: Human teeth were selected and cut perpendicularly to their long axis to expose middle/ deep dentin. Specimens were then longitudinally sectioned into halves (experimental and control halves) to create two similar bonding substrates. Experimental halves were bonded using an ElectroBond-assisted application, while control halves were bonded with disposable sponges. The adhesives tested were Adper Scotchbond 1XT and XP-BOND. Bonded specimens were submitted to the microtensile bond strength test. Additional adhesive interfaces were prepared and processed for nanoleakage investigation involving TEM examination. RESULTS: The microtensile bond test revealed higher values (p < 0.05) for both adhesives if ElectroBond was used during layering (55.5 +/- 7.9 MPa for Adper Scotchbond 1XT and 54.7 +/- 7.1 MPa for XP-BOND) compared to the conventional mechanical adhesive application technique (41.1 +/- 6.1 MPa for Adper Scotchbond 1XT and 38.0 +/- 7.8 MPa for XP-BOND). No difference between the two adhesives was found under the same application conditions. With electricity-assisted application, TEM micrographs revealed a significant decrease in nanoleakage expression compared to the controls. CONCLUSION: The use of an electric current produced by ElectroBond during the application of two-step etch-and-rinse adhesives may enhance resin impregnation, thus improving dentin hybridization. Further studies should be done to confirm that this device can similarly improve adhesive application in vivo.
Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Técnicas Electroquímicas , Grabado Ácido Dental , Resinas Compuestas/química , Filtración Dental/clasificación , Humanos , Ensayo de Materiales , Microscopía Electrónica de Transmisión , Cementos de Resina/química , Tinción con Nitrato de Plata , Método Simple Ciego , Estrés Mecánico , Propiedades de Superficie , Resistencia a la TracciónRESUMEN
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.