Insights on Ceramics as Dental Materials. Part II: Chemical Surface Treatments

The purpose of surface treatment (conditioning) methods on dental ceramics is to improve the retention and bonding between the enamel or the dentin and ceramic veneer, with the help of resin composite luting cements. These types of surface treatments include chemically altering the surface of ceramics with some specific acidic etchants followed by applying a silane coupling agent (silane). The silane currently used in dentistry is 3-methacryloxypropyltrimethoxysilane, a hybrid organic-inorganic trialkoxy ester monomer, which is diluted in an acidified water-ethanol solvent system. Such silane primers are said to be pre-hydrolyzed. Some oxide ceramics with high crystalline content, such as alumina and zirconia, cannot be easily etched with acid etchants. They should be silica-coated and silanized prior to bonding. A silane coupling agent should be applied after silica-coating to the ceramic surface to achieve chemical bonding and the optimal durable bond strength. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

EVALUATION ON RESIDUAL MONOMER OF HDDMA MATRIX SYSTEM ON FIDER REINFORCED CONDOSITES (FRC) : EVALUASI MONOMER RESIDU DARI SISTEM MATRIKS HDDMA PADA FIDER REINFORCED CONDOSITES(FRC)

Matrix system used bis-GMA was reported hazardously. An alternative monomer such as 1,6-hexanediol dimethacrylate(HDDMA) was under research. The aim of this study was to evaluate residual monomer content of HDDMA basedmatrix compositions on FRCs (fiber-reinforced composites). Three monomers based on bis-GMA (Sigma-Aldrich,USA),methylmethacrylate (MMA, ProSciTech, Australia), HDDMA (Esstech, USA) were used and also camphorquinone (CQ,Esstech, USA), N,N-cyanoethyl methylaniline (CEMA, Esstech, USA), E-glass fibers (StickTech, Finland). The matrixratios (weight %) were 78.4% bis-GMA+19.6% MMA+1.0% CQ+1.0% CEMA (control-group), 78.4% HDDMA+19.6% MMA+1.0% CQ+1.0% CEMA (EXP-1group), and 49.0% HDDMA+49.0% MMA+1.0% CQ+1.0% CEMA(EXP-2group). Samples with fibers embedded in matrix were light-cured then powdered. Powder of 150mg was dilutedin acetonitrile to 10ml. The solution was filtered then injected into HPLC (20µL). Residual monomer content wasevaluated by mobile phase of acetonitrile and water of 7:3, flow rate 1mL/minute. The size of column was C185µ,125mm length, 4mm diameter. UV detection used 275nm. Data were analyzed by ANOVA. The result showed theaverage of residual monomer content (in %) was: 0.02125±0.00018 (control-group), 0.01660±0.00016 (EXP-1group),0.01676±0.00033 (EXP-2group). The ANOVA showed significant difference of monomer content among the groups(p<0.05). The LSD showed significant difference between EXP-1 and control-groups; also between EXP-2 and controlgroups (p<0.05). There was no significant difference between EXP-1 and EXP-2 groups (p>0.05). In conclusion, a resinmatrix system based on HDDMA–MMA (EXP-1 and EXP-2 groups) revealed significant difference of residualmonomer content to bis-GMA–MMA (control-group) system. The HDDMA-MMA matrix system had less residualmonomer content than bis-GMA-MMA

Fracture strength and fractographic analysis of zirconia copings treated with four experimental silane primers

This study evaluated and compared the effect of new four experimental silane coupling agents on ‎the fracture strength of zirconia copings. The findings were supported with fractographic and ‎finite element analyses. All together 125 zirconia copings with a wall thickness of 0.6mm were ‎fabricated on identical nickel-chromium master dies and then divided randomly into five groups ‎‎(n = 25). Four test groups were prepared according the experimental silane primer (labeled: ‎OIWA1, OIWA2, OIWA3 and OIWA4) and one ontrol group without silanization. The silane ‎monomers used were: 3-methacryloxypropyltrimethoxysilane (in OIWA1), 3-‎acryloxypropyltrimethoxysilane (in OIWA2), 3-isocyanatopropyltriethoxysilane (in OIWA3) and ‎styrylethyltrimethoxysilane (in OIWA4). Tribochemical sandblasting (silica-coating) treatment ‎was performed to the inner surface of the copings in the test groups. All the specimens were ‎silanized at the inner surfaces of the zirconia copings. Self-adhesive universal resin cement was ‎used to cement the copings to the underlying master die. Zirconia copings were vertically loaded ‎on the cusp area until the first crack failure was occurred using Precision Universal Tester at a ‎constant crosshead speed of 1 mm/min. Then, the machine was manually controlled to cause ‎more failure to further determine the texture of fracture. Three dimensional finite element ‎analysis and fractography were performed to support the fracture strength findings. Based on the ‎finite element analysis results, zirconia silanized with 3-acryloyloxypropyltrimethoxysilane ‎showed the highest fracture strength with a mean of 963.75N (SD 4.5 N), while zirconia copings ‎silanized with 3 methacryloyloxypropyltrimethoxysilane showed a mean fracture strength value ‎of 925.65N (SD 2.4 N). Styrylethyltrimethoxysilane-silanised zirconia showed mean fracture ‎strength of 895.95N (SD 3.5 N). Adding silane coupling agents to the resin-zirconia interface ‎increased the fracture strengths significantly (ANOVA, p < 0.05). Silanization with four new ‎experimental silane primers in vitro produced significantly greater fracture strength than the ‎control group not treated with the test silane.

Effect of Surface Modification on Viability of L929 Cells on Zirconia Nanocomposite Substrat

Introduction: Zirconia bioceramic can be considered for metallic replacement in dental implant applications. A proper method of surface modification may promote better osseointegration.Methods: In study evaluated viability of fibroblast cell following surface treatment. Therefore, viability L929 cells were characterized using MTT assay and scanning electron microscopy.Results: The viability assessment determined significant differences A-Y-TZP20 without surface treatment as compared to laser surface treatment (B), laser surface treatment + hydroxyapatite-yttrium stabilized tetragonal zirconia nanocomposite coat (C) and control. This study demonstrated that L929 cells approximately proliferated and spread on A-Y-TZP20 nanocomposite disk in laser surface treatment(B), Laser surface treatment + hydroxiapatite-yttrium stabilized tetragonal zirconia nanocomposite coat (C) groups similar to control group.Conclusion: Laser surface treatment showed positive effect on the viability of L929 cells

Effects of Surface Charges on Dental Implants: Past, Present, and Future

Osseointegration is a major factor influencing the success of dental implantation. To achieve rapid and strong, durable osseointegration, biomaterial researchers have investigated various surface treatment methods for dental subgingival titanium (Ti) implants. This paper focuses on surface-charge modification on the surface of titanium dental implants, which is a relatively new and very promising methodology for improving the implants’ osseointegration properties. We give an overview on both theoretical explanations on how surface-charge affects the implants' osseointegration, as well as a potential surface charge modification method using sandblasting. Additionally, we discuss insights on the important factors affecting effectiveness of surface-charge modification methods and point out several interesting directions for future investigations on this topic

Effect of drying time of 3-methacryloxypropyltrimethoxysilane on the shear bond strength of a composite resin to silica-coated base/noble alloys

Objectives. In this in vitro study, the effect of various drying (surface reaction) times of a commercial silane, other than that recommended by the manufacturer (at least 5 min), on the bond strength between the resin composite and silica coated base and noble alloys was evaluated. Methods. A total of 112 disc specimens (9 mm diameter and 0.5 mm thickness) were cast out of two types of alloy designed for ceramic firing, one of which was a noble (Degunorm) (gold– silver–platinum) and the other a base alloy (Wiron 99) (nickel–chromium–molybdenum). The specimens were assigned to two main groups according to each alloy type. These two main groups were further divided into seven subgroups, having eight specimens each. The specimens of both alloy types were airabraded with 30 mm silica (SiO2) coated alumina (Al2O3) (CoJetw-Sand, ESPE, Seefeld, Germany). The conditioned surfaces were coated with 3-thacryloxypropyltrimethoxysilane(MPS) and were allowed to react and dry for 1, 2, 3, 4, 5, 6, and 7 min, respectively, before the opaquer was applied. Immediately after the waiting periods for the silane to dry, first opaquer and then resin composite were applied. After storage in water for 30 days at 37 8C and thermocycling (5000 cycles, 5–55 8C), shear tests were performed using the universal testing machine at a crosshead speed of 0.5 mm/min. Results. Analysis of data showed no significant difference in bond strength for any silane drying and reaction period for both base and noble alloys between 1 and 7 min (ANOVA, P ¼ 0:05) (Degunorm: 5.8–7.4 MPa and Wiron 99: 7.2–10.2 MPa, respectively). Bond strengths of resin composite to base alloys were significantly higher than those to noble alloys at 2, 3 and 5 min (P ¼ 0:0045; P ¼ 0:05; P ¼ 0:002; respectively). Significance. In order to optimize the flow of laboratory work, the silane solution drying time might be reduced to 1 min for both base and noble alloys