Effect of filler ratio in adhesive systems on the shear bond strength of resin composite to porcelains

Do different protocols affect the success rate or bond strength of glass-ceramics repaired with composite resin? A systematic review and meta-analysis

STATEMENT OF PROBLEM

Intraoral repair techniques prevent unnecessary replacement of ceramic restorations, thereby increasing the survival rate. However, adhesion between ceramics and the composite resin is challenging and how different protocols influence adhesion is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to analyze the influence of different protocols on repairing glass-ceramic surfaces with composite resins.

MATERIAL AND METHODS

PubMed, Scopus, ISI Web of Science, and Embase electronic databases were searched to select studies comparing bond strength values or survival rates of glass-ceramic repaired with composite resins using different surface treatment protocols. No publication year or language restriction was applied. Data sets were extracted from all included studies, and the mean differences calculated. A 95% confidence interval was calculated by using the random effect model (Rev Man 5.4).

RESULTS

The search identified 5037 studies, and 165 were assessed for eligibility. Finally, 123 in vitro studies were included in the systematic review and 48 in the meta-analysis. Considering different glass-ceramics, bond strength tests, and aged or not aged specimens, 37 meta-analyses found the effect of repair protocols: only adhesive, silane plus adhesive alone or preceded by hydrofluoric (HF) acid, airborne-particle abrasion (APA) with Al2O3 particles, silica-coated APA (SCAPA), diamond rotary instrument (DRI), and laser irradiation (LI).

CONCLUSIONS

For feldspathic porcelain, HF acid, APA, SCAPA, or DRI improved the repair micromechanical retention; applying silane is essential to HF-conditioned surfaces but the use of adhesive is optional when silane is applied. Results for leucite and lithium disilicate were inconclusive in terms of suggesting a treatment other than HF acid plus silane and adhesive applications.

Antibacterial and Physicochemical Properties of Orthodontic Resin Cement Containing ZnO-Loaded Halloysite Nanotubes

Demineralized white lesions are a common problem when using orthodontic resin cement, which can be prevented with the addition of antibacterial substances. However, the addition of antibacterial substances such as zinc oxide alone may result in the deterioration of the resin cement's functions. Halloysite nanotubes (HNTs) are known to be biocompatible without adversely affecting the mechanical properties of the material while having the ability to load different substances. The purpose of this study was to prepare orthodontic resin cement containing HNT fillers loaded with ZnO (ZnO/HNTs) and to investigate its mechanical, physical, chemical, and antibacterial properties. A group without filler was used as a control. Three groups containing 5 wt.% of HNTs, ZnO, and ZnO/HNTs were prepared. TEM and EDS measurements were carried out to confirm the morphological structure of the HNTs and the successful loading of ZnO onto the HNTs. The mechanical, physical, chemical, and antibacterial properties of the prepared orthodontic resin cement were considered. The ZnO group had high flexural strength and water absorption but a low depth of cure (p < 0.05). The ZnO/HNTs group showed the highest shear bond strength and film thickness (p < 0.05). In the antibacterial test, the ZnO/HNTs group resulted in a significant decrease in the biofilm's metabolic activity compared to the other groups (p < 0.05). ZnO/HNTs did not affect cell viability. In addition, ZnO was cytotoxic at a concentration of 100% in the extract. The nanocomposite developed in this study exhibited antimicrobial activity against S. mutans while maintaining the mechanical, physical, and chemical properties of orthodontic resin cement. Therefore, it has the potential to be used as an orthodontic resin cement that can prevent DWLs.

Modelling ATR-FTIR Spectra of Dental Bonding Systems to Investigate Composition and Polymerisation Kinetics

Component ratios and kinetics are key to understanding and optimising novel formulations. This warrants investigation of valid methods. Attenuated Total Reflectance Fourier Transform Infra-Red (ATR)-FTIR spectra of separate primers/adhesives were modelled using summed spectra of solvents (water, ethanol), methacrylate monomers (HEMA (hydroxyethyl methacrylate), Bis-GMA (bisphenol A glycidyl methacrylate), and 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)), and fillers, multiplied by varying fractions. Filler loads were obtained following their separation from the adhesives, by analysing three repetitions (n = 3). Spectral changes during light exposure at 37 °C (20 s, LED 1100-1330 mW/cm2) were used to determine polymerisation kinetics (n = 3). Independent samples T-test was used for statistical analysis (significance level of 5%). FTIR modelling suggested a primer solvent percentage of OBFL (Optibond FL) (30%) was half that of CFSE (Clearfil SE 2) (60%). OBFL included ethanol and water, while CFSE included only water. Monomer peaks were largely those of HEMA with lower levels of phosphate monomers. OBFL/CFSE adhesive model spectra suggested that both contained equal volumes of Bis-GMA/HEMA, with CFSE having 10-MDP. Filler levels and spectra from OBFL (48 wt.%) and CFSE (5 wt.%) were different. Both systems reached a 50% conversion rate within seconds of light exposure. The final conversion for OBFL (74 ± 1%) was lower compared to CFSE (79 ± 2%) (p < 0.05). ATR-FTIR is a useful method to investigate relative levels of main components in bonding systems and their polymerisation kinetics. Such information is valuable to understanding such behaviour.

Evaluation of Shear Bond Strength of Feldspathic CAD/CAM Ceramic with Dentin using 2 Bonding Agents and 2 Surface Treatments- An Invitro Study

BACKGROUND

All ceramics are the material of choice for aesthetic tooth replacements. The success of all ceramic restoration depends on the bond between the ceramic and the tooth surface hence this study was done to evaluate the shear bond strength of Feldspathic CAD/CAM ceramic with <5% hydrofluoric acid and hydrofluoric acid combined with silane coupling agent.

AIM

To evaluate the shear bond strength of Feldspathic CAD/CAM ceramic with Dentin using bonding agents Prime & Bond NT, XenoIII and surface treatments <5% hydrofluric acid, hydrofluric acid combined with silane coupling agent.

MATERIALS AND METHODS

Forty cylinders with 6mm diameter and 5mm height were milled from CEREC Blocs through CAD/CAM technology. Cerec blocks were bonded to etch freshly extracted tooth surface using a self etch and total etch bonding agent. The samples were divided into 4 groups. Group A1-Ceramic cylinders were treated with < 5% HF and bonded using Prime & Bond NT and Variolink II. Group A2- treated with < 5% HF and silane coupling agent and bonded same as group A1. Group B1- treated with < 5% HF and bonded using Xeno III and Variolink II. Group B2- treated with < 5% HF and silane coupling agent, and bonded same as Group A3. The shear bond strength was evaluated after 24 hours by Storing in distilled water in Instron 3385 universal testing machine with 10-KN force.

RESULTS

Statistical analysis was done using student's t-test and Lavene's test. The p-value <0.05 shows significant difference in bond strength between A1 and A2 & B1and B2.

CONCLUSION

The application of a silane coupling agent to the ceramic surface after etching with hydrofluoric acid increased the adhesion strength with both bonding agents. Student's t-test revealed a significant effect of silanization.

Surface treatment of dental porcelain: CO2 laser as an alternative to oven glaze

This work tested continuous CO2 laser as a surface treatment to dental porcelain and compared it to oven glaze (auto-glaze) by means of roughness and color parameters. Three commercial veneering porcelains with different crystalline content were tested: VM7, VM9, and VM13. Porcelain discs (3.5 × 2.0 mm, diameter × height) were sintered and had one side ground by a diamond bur (45 μm) simulating a chairside adjustment in a clinical office. Specimens (n = 7) were divided into the following groups: C--control (no treatment), G--auto-glaze (oven), and L--surface continuous irradiation with CO2 laser (Gem Laser, Coherent; λ = 10.6 μm). Laser was tested in three exposure times (3, 4, or 5 min) and two irradiances (45 and 50 W/cm(2)). Roughness parameters (Ra, Rz, and Rpm/Rz) were measured using a rugosimeter (Surftest 301, Mitutoyo). Color differences (ΔE) between the G and L groups were calculated (VITA Easyshade); ΔE values up to 3.3 were considered as not perceivable. A surface analysis was conducted by stereomicroscopy (Olympus SZ61) and SEM (Stereoscan 440, LEO). Crystalline content of specimens from groups C and L (50 W/cm(2), 5 min) was assessed by X-ray diffraction and then compared. Surface roughness (Ra and Rz) observed for laser-irradiated groups was similar to G for all studied porcelains. Rpm/Rz ratios were near 1.0 for all groups that indicated a sharp ridge profile for all specimens. Only one laser condition studied (50 W/cm(2), 3 min) from VM7 porcelain resulted in color difference (ΔE = 3.5) to G. Specimens irradiated with 50 W/cm(2) for 5 min presented the smoother surface observed by SEM, comparable to G. X-ray diffraction data revealed an increase in leucite crystallite size for VM9 and VM13 porcelains after laser treatment. Regarding roughness, continuous CO2 laser applied on porcelain surface was as effective as conventional oven auto-glaze.

Effect of thermocycling on the bond strength of composite resin to bur and laser treated composite resin

The objective of this study was to investigate the effect of two different surface treatments (Er:YAG laser and bur) and three different numbers of thermal cycling (no aging, 1,000, 5,000, and 10,000 cycles) on the micro-shear bond strength of repaired composite resin. Ninety-six composite blocks (4 mm × 4 mm × 1 mm) obtained with a micromatrix hybrid composite were prepared. The composite blocks were then randomly divided into four groups (n = 24), according to the thermal cycling procedure: (1) stored in distilled water at 37°C for 24 h (control group), (2) 1,000 cycles, (3) 5,000 cycles, and (4) 10,000 cycles. After aging, the blocks were further subdivided into two subgroups (n = 12), according to surface treatment. Bur and laser-treated composite surfaces were treated with an etch&rinse adhesive system. In addition, a microhybrid composite resin was bonded to the surfaces via polyethylene tubing. Specimens were subjected to micro-shear bond strength test by a universal testing machine with a crosshead speed of 0 and 5 mm/min. The data were analyzed using one-way analysis of variance and Tukey tests (α = 0.05) for micro-shear bond strengths. After conducting a bond strength test, it was found that the laser and bur-treated specimens had similar results. Aging with 10,000 thermocycles significantly affected the repair bond strength of composite resins.