Improved resin-to-dentin bond strength and durability via non-thermal atmospheric pressure plasma drying of etched dentin.

This study aimed to evaluate the improvement in strength and durability of the bond between dentin and composite resins following plasma drying of the etched dentin surface using non-thermal atmospheric pressure plasma. Plasma drying was applied to the etched dentin before applying adhesive. Conventional wet-bonding and helium (He) gas-dried bonding schemes were used as control groups. The bond strength of the composite resin to dentin was measured as the microtensile bond strength at 24 h after bonding and after 10,000 cycles of thermocycling. Hybrid layer formation was observed using micro-Raman spectroscopy and scanning electron microscopy. Although the bond-strength values were not statistically different either at 24 h after bonding or after thermocycling, the bond strength of the plasma-dried bonding group was significantly higher than the conventional wet-bonding group and He gas-dried bonding group. Micro-Raman spectral analysis revealed effective penetration of the adhesive and an improved polymerization rate of the adhesive after plasma drying. Plasma drying increased the penetration of hydrophobic resin into the collagen mesh structure, which improved mechanical bonding and long-term durability between dentin and composite resin.

Bonding of the silane containing multi-mode universal adhesive for lithium disilicate ceramics.

OBJECTIVES: This study evaluated the influence of a multi-mode universal adhesive (MUA) containing silane (Single Bond Universal, 3M EPSE) on the bonding of resin cement to lithium disilicate. MATERIALS AND METHODS: Thirty IPS e.max CAD specimens (Ivoclar Vivadent) were fabricated. The surfaces were treated as follows: Group A, adhesive that did not contain silane (ANS, Porcelain Bonding Resin, Bisco); Group B, silane (S) and ANS; Group C, hydrofluoric acid (HF), S, and ANS; Group D, MUA; Group E, HF and MUA. Dual-cure resin cement (NX3, Kerr) was applied and composite resin cylinders of 0.8 mm in diameter were placed on it before light polymerization. Bonded specimens were stored in water for 24 hours or underwent a 10,000 thermocycling process prior to microshear bond strength testing. The data were analyzed using multivariate analysis of variance (p < 0.05). RESULTS: Bond strength varied significantly among the groups (p < 0.05), except for Groups A and D. Group C showed the highest initial bond strength (27.1 ± 6.9 MPa), followed by Group E, Group B, Group D, and Group A. Thermocycling significantly reduced bond strength in Groups B, C, and E (p < 0.05). Bond strength in Group C was the highest regardless of the storage conditions (p < 0.05). CONCLUSIONS: Surface treatment of lithium disilicate using HF and silane increased the bond strength of resin cement. However, after thermocycling, the silane in MUA did not help achieve durable bond strength between lithium disilicate and resin cement, even when HF was applied.

Promotion of resin bonding to dental zirconia ceramic using plasma deposition of tetramethylsilane and benzene.

The aim of this study was to investigate the effects of plasma-enhanced deposition of an organosilane and benzene on resin bonding to a dental zirconia ceramic. A total of 70 zirconia specimens, which were polished before sintering, were randomly divided into five groups according to surface treatments before applying a dental adhesive (each group, n = 14): group 1, no previous treatment (control); group 2, plasma deposition with tetramethylsilane (TMS); group 3, plasma deposition with benzene; group 4, sequential plasma deposition with TMS and benzene; and group 5, a zirconia primer (Z-Prime Plus). A dental adhesive (Scotchbond Multi-Purpose adhesive) was applied to the surface-treated zirconia, and resin composite rods were built in to enable shear bond-strength testing. The sequential deposition of TMS and benzene showed the highest bond strength [22.7 ± 3.7 MPa (mean ± SD)], approximately twice that of Z-Prime Plus (10.3 ± 3.2 MPa). The plasma deposition with either TMS or benzene also significantly improved bond-strength values compared with the negative-control group, and their effects were not statistically different from that of Z-Prime Plus. Following plasma deposition with TMS, the introduction of silicon-oxygen-zirconium (Si-O-Zr) bonds on the zirconia surface was confirmed via X-ray photoelectron spectroscopy (XPS) analysis. Transmission electron microscopy and energy dispersive X-ray spectroscopy showed that a silica-like layer and a polymerizable carbon-rich layer were formed through sequential deposition with TMS and benzene.

Promotion of adhesive penetration and resin bond strength to dentin using non-thermal atmospheric pressure plasma.

Non-thermal atmospheric pressure plasmas (NT-APPs) have been shown to improve the bond strength of resin composites to demineralized dentin surfaces. Based on a wet-bonding philosophy, it is believed that a rewetting procedure is necessary after treatment with NT-APP because of its air-drying effect. This study investigated the effect of 'plasma-drying' on the bond strength of an etch-and-rinse adhesive to dentin by comparison with the wet-bonding technique. Dentin surfaces of human third molars were acid-etched and divided into four groups according to the adhesion procedure: wet bonding, plasma-drying, plasma-drying/rewetting, and dry bonding. In plasma treatment groups, the demineralized dentin surfaces were treated with a plasma plume generated using a pencil-type low-power plasma torch. After the adhesion procedures, resin composite/dentin-bonded specimens were subjected to a microtensile bond-strength test. The hybrid layer formation was characterized by micro-Raman spectroscopy and scanning electron microscopy. The plasma-drying group presented significantly higher bond strength than the wet-bonding and dry-bonding groups. Micro-Raman spectral analysis indicated that plasma-drying improved the penetration and polymerization efficacy of the adhesive. Plasma-drying could be a promising method to control the moisture of demineralized dentin surfaces and improve the penetration of adhesive and the mechanical property of the adhesive/dentin interface.

Performance of a novel polishing rubber wheel in improving surface roughness of feldspathic porcelain.

Replacing glazing with polishing is still controversial in terms of the surface roughness of dental porcelains. This study investigated the polishing performance of a ceramic-polishing rubber wheel (CP-RW), which contains large uniform and rounded silicon carbide particles and small diamond particles, in improving the surface roughness of two feldspathic porcelains for sintering and CAD/CAM milling. Using a confocal laser scanning microscopy, the changes in the surface roughness parameters were evaluated before and after polishing or glazing for three surface treatment groups: SofLex polishing, CP-RW polishing, and Glazing. Regardless of the parameters, all treatments reduced roughness values (repeated measures ANOVA, p<0.05). The roughness values obtained after CP-RW polishing were lower than those obtained after SofLex polishing and glazing (2-way ANOVA, p<0.05). Polishing both ceramics with CP-RW made the surfaces smooth with the lowest roughness values in all parameters. The effect was dependent on the materials used.

Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability.

Comparison of shear test methods for evaluating the bond strength of resin cement to zirconia ceramic.

OBJECTIVE: This study compared the sensitivity of three shear test methods for measuring the shear bond strength (SBS) of resin cement to zirconia ceramic and evaluated the effects of surface treatment methods on the bonding. MATERIALS AND METHODS: Polished zirconia ceramic (Cercon base, DeguDent) discs were randomly divided into four surface treatment groups: no treatment (C), airborne-particle abrasion (A), conditioning with Alloy primer (Kuraray Medical Co.) (P) and conditioning with Alloy primer after airborne-particle abrasion (AP). The bond strengths of the resin cement (Multilink N, Ivoclar Vivadent) to the zirconia specimens of each surface treatment group were determined by three SBS test methods: the conventional SBS test with direct filling of the mold (Ø 4 mm × 3 mm) with resin cement (Method 1), the conventional SBS test with cementation of composite cylinders (Ø 4 mm × 3 mm) using resin cement (Method 2) and the microshear bond strength (µSBS) test with cementation of composite cylinders (Ø 0.8 mm × 1 mm) using resin cement (Method 3). RESULTS: Both the test method and the surface treatment significantly influenced the SBS values. In Method 3, as the SBS values increased, the coefficients of variation decreased and the Weibull parameters increased. The AP groups showed the highest SBS in all of the test methods. Only in Method 3 did the P group show a higher SBS than the A group. CONCLUSIONS: The µSBS test was more sensitive to differentiating the effects of surface treatment methods than the conventional SBS tests. Primer conditioning was a stronger contributing factor for the resin bond to zirconia ceramic than was airborne-particle abrasion.

Peri-implant bone formation of non-thermal atmospheric pressure plasma-treated zirconia implants with different surface roughness in rabbit tibiae.

OBJECTIVES: The aim of this study was to evaluate and compare the osseointegration of powder-injection molded (PIM) zirconia implants in rabbit tibiae with or without He plasma treatment. MATERIAL AND METHODS: Twenty-five rabbits received 4 types of external hex implants with identical geometry in the tibiae: PIM zirconia implants, roughened PIM zirconia implants, plasma-treated PIM zirconia implants, and plasma-treated roughened PIM zirconia implants. The contact angles of the four types of implants were evaluated. Removal torque tests and histomorphometric analyses were performed. RESULTS: The plasma treatment markedly enhanced the hydrophilicity, but did not seem to change the surface topography of the PIM zirconia implants. There were statistically significant differences in the bone-to-implant contact (BIC) ratios, bone volume (BV/TV), and removal torque values (RTQ) among the tested implant types (P < 0.001). The plasma-treated implants exhibited significantly higher BIC and BV/TV values than the untreated implants. However, the removal torque values favored the rough surface. CONCLUSIONS: The He plasma treatments on PIM zirconia implants made the surface more hydrophilic and enhanced the osseointegration of the implants without changing the micro-topography.

Plasma in dentistry: a review of basic concepts and applications in dentistry.

OBJECTIVE: Plasma-related technologies are essential in modern industries. Recently, plasma has attracted increased attention in the biomedical field. This paper provides a basic knowledge of plasma and a narrative review of plasma applications in dentistry. MATERIALS AND METHODS: To review plasma applications in dentistry, an electronic search in PubMed, SCOPUS and Google scholar up to December 2012 was done. This was followed by extensive hand searching using reference lists from relevant articles. CONCLUSION: There have been attempts to apply plasma technology in various fields of dentistry including surface modifications of dental implants, adhesion, caries treatment, endodontic treatment and tooth bleaching. Although many studies were in early stages, the potential value of plasma for dental applications has been demonstrated. To enlarge the scope of plasma applications and put relevant research to practical use, interdisciplinary research with participation of dental professionals is required.

Effect of the applied power of atmospheric pressure plasma on the adhesion of composite resin to dental ceramic.

PURPOSE: To evaluate the effect of applied power on dental ceramic bonding of composite resin using nonthermal atmospheric pressure plasma (APP). MATERIALS AND METHODS: A pencil-type APP torch was used to modify the surface chemical composition and hydrophilicity of dental ceramic and to improve the adhesion of composite resin to the surface. The effect of the applied power on chemical changes of the plasma polymer on a ceramic surface and the adhesive strength between the composite resin and feldspathic porcelain were examined. Adhesion was evaluated by comparing shear bond strengths (SBS) using the iris method. The chemical composition of the plasma polymer deposited on the ceramic surface was evaluated using x-ray photoelectron spectroscopy (XPS). Hydrophilicity was evaluated by contact angle measurements. The fracture mode at the interface was also evaluated. RESULTS: The APP treatment was effective and the SBS of the experimental groups were significantly higher than those of the negative control group (p < 0.05). Moreover, the SBS obtained with the APP treatment at the highest input voltage was statistically similar to the gold standard of HF etching and silane coupling-agent coating. Two-thirds of the fractures observed in the specimens bonded with application of APP were mixed and cohesive fractures. CONCLUSION: Application of APP enhanced adhesion by producing carboxyl groups on the ceramic surface and as a result by improving surface hydrophilicity. The carboxyl group contents in the plasma polymer on the ceramic surface increased as the applied power increased.