High bonding strength between zirconia and composite resin based on combined surface treatment for dental restorations.

Zirconia is the preferred material for dental restorations; however, dental restorations are usually affected by zirconia fractures due to chipping and delamination of the veneer ceramic. One effective solution for repairing chemically inert zirconia frameworks is to strongly chemically bond them with the composite resin via surface modification. Thus, the bonding strength between the zirconia and composite resin determines the performance of dental restoration. Herein, we investigate the shear bond strength between zirconia ceramic and two ceramic repair systems before and after thermal cycling based on different surface pretreatments, including air-abrasion and a novel silane coupling agent. When treated with combined sandblasting, novel silane and 10-methacryloyloxydecyl hydrogen phosphate act as a bonding agent for the zirconia surface, and the maximum shear bond strength achieves 27.5 MPa, as measured by a universal testing machine through the average of 16 separate measurements. The results show that the combined treatment resists the interface damage caused by expansion and contraction during thermal cycling. The long-term bond durability is due to the micro-mechanical bond force formed by resin and ceramic, and the chemical bonds of Zr-O-Si at the interface. Results indicate that selective pretreating the surface results in high bond strength between the zirconia and the composite resin, which is meaningful to optimize dental restoration.

Enhanced bonding strength between lithium disilicate ceramics and resin cement by multiple surface treatments after thermal cycling.

All-ceramic restoration has become a popular technology for dental restoration; however, the relative bond strength between the ceramic and resin limits its further application. Long-term high bond strength, especially after thermal cycling, is of great importance for effective restoration. The effect of physical and/or chemical surface treatments on bonding durability is seldom reported. To overcome this problem, we investigate the bond strength between lithium disilicate ceramics (LDC) and two kinds of resin cements before and after thermal cycling for a variety of surface treatments including hydrofluoric acid, two kinds of silane and a combined effect. The shear bond strength in every group is characterized by universal mechanical testing machine averaged by sixteen-time measurements. The results show that when treated with HF and a mixed silane, the LDC surface shows maximum bonding strengths of 27.1 MPa and 23.3 MPa with two different resin cements after 5000 thermal cycling, respectively, indicating an excellent ability to resist the damage induced by cyclic expansion and contraction. This long-term high bond strength is attributed to the combined effect of micromechanical interlocking (physical bonding) and the formation of Si-O-Si and -C-C- at the interface (chemical bonding). This result offers great potential for enhancing bond strength for all-ceramic restoration by optimizing the surface treatment.

[Zoledronic acid incorporated in chitosan/calcium phosphate ceramic: characterization and in vitro response of osteoblast cells].

OBJECTIVE: To develop a new local delivery system, zoledronic-acid-loaded chitosan/calcium phosphate ceramic, and to determine its characterization and in vitro response of osteoblast cells. METHODS: Zoledronic-acid-loaded chitosan/calcium phosphate ceramic were prepared by solution casting method at a concentration of 10(-5), 10(-4), and 10(-3) mol/L, respectively. The physicochemical properties of the resulting materials were determined using SEM and FTIR. Drug absorbance was measured using CCK-8 colorimetric assay and alkaline phosphatase assay to detect the effect of drug-loaded materials on the proliferation and differentiation of osteoblasts. RESULTS: After ZOL loading, SEM showed that porous calcium phosphate ceramic was coated with chitosan evenly. The IR spectra indicated that drug absorption peaks were shifted and a new one was formed for the drug-loaded biomaterials. The material at the highest concentration could inhibit the proliferation and alkaline phosphatase activities of osteoblast cells, but no such effect was found at a drug-loading concentration of 10(-4)-10(-5) mol/L. CONCLUSION: We confirmed that the local delivery system in this study has ability of loading ZOL. The biomaterial with high drug concentrations inhibits the proliferation and differentiation of osteoblasts, but not when the drug concentrations are low.

[Preparation of zoledronic-acid-loaded collagen membrane].

OBJECTIVE: To develop a new local delivery system, osteoclastic-inhibitor-loaded collagen membrane, and to evaluate its drug loading and drug release properties. METHODS: Efforts were made to develop the drug-loaded membranes by combining two commercially available collagen barrier membranes (Bio-Gide and BME-10X) with zoledronic acid (ZA). The physicochemical and pharmacological properties of resulting materials were determined using SEM, EDS, FTIR, and HPLC. RESULTS: After ZA loading, the micropores between the thin collagen fibers in the Bio-Gide disappeared, whereas crystalloid powders appeared on the surface of pore walls in BME-10X. Phosphorus was detected on both drug-loaded membranes. The Amides shifted. With the same drug solution, Bio-Gide presented larger amount of ZA loading and slower ZA release than BME-10X. ZA loading did not affect the 3D fiber network and the degradation of membranes. CONCLUSION: Both collagen membranes load ZA successfully and delay drug release. But Bio-Gide shows higher loading values and slower release than BME-10X.