METHODS: Experimental adhesives modified with different fractions of dioctadecyldimethyl ammonium bromide quaternary ammonium and riboflavin (QARF) were formulated. Dentine specimens were bonded to resincomposites with control or the experimental adhesives to be evaluated for bond strength, interfacial morphology, micro-Raman analysis, nano-CT and nano-leakage expression. In addition, the antibacterial and biocompatibilities of the experimental adhesives were investigated. The endogenous proteases activities and their molecular binding-sites were studied.
RESULTS: Modifying the experimental adhesives with QARF did not adversely affect micro-tensile bond strength or the degree of conversion along with the demonstration of anti-proteases and antibacterial abilities with acceptable biocompatibilities. In general, all experimental adhesives demonstrated favourable bond strength with increased and improved values in 1% QARF adhesive at 24 h (39.2 ± 3.0 MPa) and following thermocycling (34.8 ± 4.3 MPa).
SIGNIFICANCE: It is possible to conclude that the use of QARF with defined concentration can maintain bond strength values when an appropriate protocol is used and have contributed in ensuring a significant decrease in microbial growth of biofilms. Incorporation of 1% QARF in the experimental adhesive lead to simultaneous antimicrobial and anti-proteolytic effects with low cytotoxic effects, acceptable bond strength and interfacial morphology.
MATERIALS AND METHODS: Three different makes of ceramic brackets, Pure Sapphire(M), Clarity™ ADVANCED(P) and Dual Ceramic(P) were used. Eighteen specimens of each make were prepared and allocated to three groups (n = 6). MARC(®)-resin calibrator was used to determine the light curing unit (LCU) tip irradiance (mW/cm(2)) and TLE (J/cm(2)) transmitted through the ceramic brackets, and through ceramic bracket plus Transbond™ XT Light Cure Adhesive, for 5, 10 and 20 s. Vickers-hardness values at the bottom of the cured adhesive were determined. Statistical analysis used one-way analysis of variance (ANOVA); P = 0.05.
RESULTS: TLE transmission rose significantly among all samples with increasing exposure durations. TLE reaching the adhesive- enamel interface was less than 10 J/cm(2), and through monocrystalline and polycrystalline ceramic brackets was significantly different (P
METHODS: The interaction between HIFU waves and dentin-surface in terms of structural, mechanical and chemical variations were investigated by SEM, TEM, AFM, nano-indentation and Raman-analysis. The bonding between HIFU-treated dentin and two-step, etch-and-rinse, adhesive was preliminary explored by characterizing dentin-bound proteases activities, resin-dentin interfacial morphology and bond-durability with HIFU exposure at different time-points of 60, 90 and 120 s compared to conventional acid-etching technique.
RESULTS: With the increase in HIFU exposure-time from 60-to-120 s, HIFU waves were able to remove the smear-layer, expose dentinal-tubules and creating textured/rough dentin surface. In addition, dentin surfaces showed a pattern of interlocking ribbon-like minerals-coated collagen-fibrils protruding from the underlaying amorphous dentin-background with HIFU exposure for 90 s and 120 s. This characteristic pattern of dentin-surface showing inorganic-minerals associated/aligned with collagen-fibrils, with 90-to-120 s HIFU-treatment, was confirmed by the Raman-analysis. HIFU-treated specimens showed higher nano-indentation properties and lower concentrations of active MMP-2 and Cathepsin-K compared to the acid-etched specimens. The resin-dentin bonded interface revealed the partial/complete absence of the characteristic hybrid-layer formed with conventional etch-and-rinse bonding strategy. Additionally, resin-infiltration and resin-tags formation were enhanced with the increase in HIFU exposure-time to 120 s. Although, all groups showed significant decrease in bond-strength after 12 months compared to 24 h storage in artificial saliva, groups exposed to HIFU for 90 s and 120 s showed significantly higher μTBS compared to the control acid-etched group.
SIGNIFICANCE: The implementation of HIFU-technology for dental hard-tissues treatment could be of potential significance in adhesive/restorative dentistry owing to its ability of controlled, selective and localised combined tissue alteration/ablation effects.
METHODS: Dentin slabs were treated with 0.1% riboflavin-5-phosphate modified (powder added slowly while shaking and then sonicated to enhance the dispersion process) Universal Adhesive Scotch Bond and Zipbond™ along with control (non-modified) and experimental adhesives, photoactivated with blue light for 20s. Hydroxyproline (HYP) release was assessed after 1-week storage. Elastic-modulus testing was evaluated using universal testing machine at 24 h. Resin-dentin interfacial morphology was assessed with scanning electron-microscope, after 6-month storage. 0.1% rhodamine dye was added into each adhesive and analyzed using CLSM. Detection of free amino groups was carried out using ninhydrin and considered directly proportional to optical absorbance. Collagen molecular confirmation was determined using spectropolarimeter to evaluate and assess CD spectra. For molecular docking studies with riboflavin (PDB ID file), the binding pocket was selected with larger SiteScore and DScore using Schrodinger PB software. After curing, Raman shifts in Amide regions were obtained at 8 μm levels. Data were analyzed using Two-way analysis of variance (ANOVA, p ≤ 0.05) and Tukey-Kramer multiple comparison post hoc tests.
RESULTS: At baseline, bond strength reduced significantly (p ≤ 0.05) in control specimens. However, at 6 months' storage, UVA Zipbond™ had significantly higher μTBS. Resin was able to diffuse through the porous demineralized dentin creating adequate hybrid layers in both 0.1%RF modified adhesives in CLSM images. In riboflavin groups, hybrid layer and resin tags were more pronounced. The circular dichroism spectrum showed negative peaks for riboflavin adhesive specimens. Best fitted poses adopted by riboflavin compound are docked with MMP-2 and -9 proteases. Amide bands and CH2 peaks followed the trend of being lowest for control UA Scotch bond adhesive specimens and increasing in Amides, proline, and CH2 intensities in 0.1%RF modified adhesive specimens. All 0.1%RF application groups showed statistically significant (p
Materials and Methods: Ninety aluminum oxide ceramic (Turkom-Ceramic Sdn. Bhd., Kuala Lumpur, Malaysia) specimens were produced and divided into nine groups to receive the following surface treatments: control group, no treatment (Group C), sandblasting (Group B), silica coating (Group S), erbium: yttrium-aluminum-garnet (Er:YAG) laser irradiation at 150 mJ 10 Hz (Group L1), Er:YAG laser irradiation at 300 mJ 10 Hz (Group L2), sandblasting + L1 (Group BL1), sandblasting + L2 (Group BL2), silica coating + L1 (Group SL1), and silica coating + L2 (Group SL2). After surface treatments, surface roughness (SR) values were measured and surface topography was evaluated. Resin cement was applied on the specimen surface, and shear bond strength (SBS) tests were performed. Data were statistically analyzed using one-way ANOVA and Tukey's multiple comparisons at a significance level of P < 0.05.
Results: Group S, SL1, and SL2 showed significantly increased SR values compared to the control group (P < 0.05); therefore, no significant differences were found among the SR values of Groups B, BL1, BL2, L1, and L2 and the control group (P > 0.05). Group S showed the highest SBS values, whereas the control group showed the lowest SBS values.
Conclusion: Silica coating is the most effective method for resin bonding of high strength ceramic, but Er:YAG laser application decreased the effectiveness.
MATERIALS AND METHODS: An experimental adhesive system based on bis-GMA, HEMA and hydrophobic monomer was doped with RF0.125 (RF - Riboflavin) or RF/VE-TPGS (0.25/0.50) and submitted to μTBS evaluation. Resin dentine slabs were prepared and examined using SEM and TEM. Adhesion force was analysed on ends of AFM cantilevers deflection. Quenched peptide assays were performed using fluorescence scanner and wavelengths set to 320nm and 405nm. Cytotoxicity was assessed using human peripheral blood mononuclear cell line. Molecular docking studies were carried out using Schrödinger small-molecule drug discovery suite 2018-2. Data from viable cell results was analyzed using one-way ANOVA. Bond strength values were analysed by two-way ANOVA. Nonparametric results were analyzed using a Kruskal-Wallis test at a 0.05 significance level.
RESULTS: RF/VE-TPGS0.25 groups showed highest bond strength results after 24-h storage in artificial saliva (p<0.05). RF/VE-TPGS0.50 groups showed increased bond strength after 12-months of ageing. RF/VE-TPGS modified adhesives showed appreciable presence of a hybrid layer. Packing fraction indicated solid angle profiles describing well sized density and topology relations for the RF/VE-TPGS adhesives, in particular with the RF/VE-TPGS0.50 specimens. Qualitative analysis of the phenotype of macrophages was prominently CD163+ in the RF/VE-TPGS0.50. Both the compounds showed favourable negative binding energies as expressed in terms of 'XP GScore'.
CONCLUSION: New formulations based on the incorporation of RF/VE-TPGS in universal adhesives may be of significant potential in facilitating penetration, distribution and uptake of riboflavin within the dentine surface.
MATERIALS AND METHODS: Forty Turkom-Cera ceramic disks (10 mm × 3 mm) were prepared and randomly divided into four groups. The disks were wet ground to 1000-grit and subjected to four surface treatments: (1) No treatment (Control), (2) sandblasting, (3) silane application, and (4) sandblasting + silane. The four groups of 10 specimens each were bonded with Panavia-F resin cement according to manufacturer's recommendations. The SBS was determined using the universal testing machine (Instron) at 0.5 mm/min crosshead speed. Failure modes were recorded and a qualitative micromorphologic examination of different surface treatments was performed. The data were analyzed using the one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests.
RESULTS: The SBS of the control, sandblasting, silane, and sandblasting + silane groups were: 10.8 ± 1.5, 16.4 ± 3.4, 16.2 ± 2.5, and 19.1 ± 2.4 MPa respectively. According to the Tukey HSD test, only the mean SBS of the control group was significantly different from the other three groups. There was no significant difference between sandblasting, silane, and sandblasting + silane groups.
CONCLUSION: In this study, the three surface treatments used improved the bond strength of resin cement to Turkom-Cera disks.
CLINICAL SIGNIFICANCE: The surface treatments used in this study appeared to be suitable methods for the cementation of glass infiltrated all-ceramic restorations.
MATERIALS AND METHODS: A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) were immediately bonded with resin cement (Rely X U200) after UV irradiation. Shear bond strength (SBS) MPa was measured, and the dislodged area of post surfaces was examined with scanning electron microscopes. Changes in surface roughness (Ra) of the FRC group after UV irradiation were observed (n = 3) using atomic force microscopy. Data of SBS were statistically analyzed using one-way analysis of variance, followed by multiple comparisons (P < 0.05).
RESULTS: SBS was significantly higher for 20 min of UV irradiation of the FRC group while significantly higher SBS was observed with 15 min of UV irradiation of the KOR group. Resin cement was more evident (cohesive failure) on the dislodged post surface of the UV treated groups compared with the control. The surface roughness of the FRC post was Ra = 175.1 nm and Ra = 929.2 nm for the control and the 20 min group, respectively.
CONCLUSIONS: Higher surface roughness of the UV irradiated group indicated formation of mechanical retention on the fiber post surface. Evidence of cohesive failure was observed which indicated higher SBS of fiber post with the UV irradiated group.
METHODS: Different volume percentages of HEMA were tested in four experimental silane-based primer solutions (additions of HEMA: 0, 5.0 vol%, 25.0 vol% and 50.0 vol%). An experimental silane blend (primer) of 1.0 vol% 3-isocyanatopropyltrimethoxysilane (ICMS) + 0.5% bis-1,2-(triethoxysilyl) ethane (BTSE) was prepared and used. The experimental primers together with the control group were applied onto acid-etched premolars for attachment of orthodontic brackets. After artificial aging by thermocycling the shear-bond strength was measured. The fractured surfaces of all specimens were examined under scanning electron microscopy (SEM) to evaluate the failure mode on the enamel surface.
RESULTS: The experimental primers showed the highest shear-bond strength of 21.15 MPa (SD ± 2.70 MPa) and with 25 vol% showed a highly significant increase (P < 0.05) in bond strength. The SEM images showed full penetration of adhesive agents when using silane-based primers. In addition, the SEM images suggested that the predominant failure type was not necessarily the same as for the failure propagation.
CONCLUSIONS: This preliminary study suggested that nonacidic silane-based primers with HEMA addition might be an alternative to for use as adhesion promoting primers.
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