Orthodontic bonding to silicate ceramics: impact of different pretreatment methods on shear bond strength between ceramic restorations and ceramic brackets

Objective The study aims to investigate the shear bond strength (SBS) between silicate ceramic restorations and ceramic brackets after different pretreatments and aging methods. Material and methods Leucite (LEU) and lithium disilicate (LiSi) specimens were pretreated with (i) 4% hydrofluoric acid + silane (HF), (ii) Monobond Etch&Prime (MEP), (iii) silicatization + silane (CoJet), and (iv) SiC grinder + silane (SiC). Molars etched (phosphoric acid) and conditioned acted as comparison group. SBS was measured after 24 h (distilled water, 37 °C), 500 × thermocycling (5/55 °C), and 90 days (distilled water, 37 °C). Data was analyzed using Shapiro–Wilk, Kruskal–Wallis with Dunn’s post hoc test and Bonferroni correction, Mann–Whitney U, and Chi2 test (p < 0.05). The adhesive remnant index (ARI) was determined. Results LEU pretreated with MEP showed lower SBS than pretreated with HF, CoJet, or SiC. LiSi pretreated with MEP resulted in lower initial SBS than pretreated with HF or SiC. After thermocycling, pretreatment using MEP led to lower SBS than with CoJet. Within LiSi group, after 90 days, the pretreatment using SiC resulted in lowest SBS values. After HF and MEP pretreatment, LEU showed lower initial SBS than LiSi. After 90 days of water storage, within specimens pretreated using CoJet or SiC showed LEU higher SBS than LiSi. Enamel presented higher or comparable SBS values to LEU and LiSi. With exception of MEP pretreatment, ARI 3 was predominantly observed, regardless the substrate, pretreatment, and aging level. Conclusions MEP pretreatment presented the lowest SBS values, regardless the silicate ceramic and aging level. Further research is necessary. Clinical relevance There is no need for intraoral application of HF for orthodontic treatment.

Nano Silicate Ceramic Coating Material Applied to Increase the Emissivity and Efficiency of Primary Reformer Radiant

Nano silicate ceramic material prepared in this research for coating the walls of the primary reformer unit in the state company of fertilizers. It is applied to increase the emissivity and thermal efficiency to improve the properties of insulation materials. Moreover, it is increasing the working operation time for catalyst tubes and reducing the carbon dioxide emissions. Nano coating materials were prepared by using different refractory materials that include silica, filed spar, alumina, manganese dioxide and magnesium oxide. The preparation method was done by, calcination and firing these materials then crashing to get extremely fine powder. The results show that coating materials consist mainly from quartz crystalline and glassy phase structure with a grain size of 158 nm and penetration between 10 to 20 mm when using different concentration 0.5 to 1.0 % for total mix. The emissivity of primary reformer insulation materials was increased with 30 % comparing with insulation materials without coating.

Fatigue Behavior of Monolithic Zirconia-Reinforced Lithium Silicate Ceramic Restorations: Effects of Conditionings of the Intaglio Surface and the Resin Cements

SUMMARY Objective: This study assessed the effect of conditioning of the intaglio surface and resin cements on the fatigue behavior of zirconia-reinforced lithium silicate ceramic (ZLS) restorations cemented to a dentin analogue. Methods: ZLS ceramic (Ø=10 mm, thickness=1.5 mm) and dentin analogue (Ø=10 mm, thickness=2.0 mm) discs were produced and allocated according to the study factors, totaling nine study groups: ceramic surface treatment (three levels: hydrofluoric acid etching [HF]; self-etching ceramic primer [EP]; tribochemical silica coating [TBS]) and resin cement (three levels: 10-methacryloyloxydecyl dihydrogen phosphate [nMDP]; MDP–containing conventional resin cement [MDP]; self-adhesive resin cement [SA]). The ceramic bonding surfaces were treated and cemented on the dentin analogue, and all the specimens were aged for 5000 thermal cycles (5°C–55°C) prior to fatigue testing. The stepwise fatigue test (20 Hz frequency) started with a load of 400 N (5000 cycles) followed by steps of 500, 600, and up to 1800 N (step-size: 100 N) at a maximum of 10,000 cycles each step. The specimens were loaded until failure (crack), which was detected by light transillumination and visual inspection at the end of each step. The fatigue failure load and number of cycles for failure data were analyzed by the Kaplan-Meier (log-rank test; α=0.05). Topographic and fractographic analyses were also performed. Results: HF- (973.33–1206.67 N) and EP- (866.67–1066.67 N) treated specimens failed at statistically similar loads and higher than TBS (546.67–733.33 N), regardless of the cement used. All the fractographical inspections demonstrated failure as radial crack. Conclusion: The HF and EP treatments promoted better mechanical fatigue behavior of the ceramic restoration, while tribochemical silica coating induced worse fatigue results and should be avoided for treating the ZLS surface prior to bonding.