| Background:Abutment is the important structure, which connects implant and the upper prosthesis. Pure titanium abutment is applied to the present clinical restorations, which have good biocompatibility and friction pair. However, if the gingival is thinner or the shoulder of the abutment lies higher, the exposition of metal affect aesthetics especially in the front teeth area, which could lower the patients’ satisfaction level. Zirconia abutment has excellent biocompatibility and aesthetic performance can meet the requirements of patients and doctors, while it has some shortages, such as low strength, high brittleness and easy to break off. In terms of the defection of aesthetic and mechanical properties of two kinds of abutment, we increased zirconia coating in the neck of the pure titanium abutment. The interface connection was kept among pure titanium abutment, titanium implant and central screw which avoided the friction pair between different materials. In hence, the research aims to solve the above problems and design a new type abutment. The new abutment will have a broad clinical application value and market prospect, which not only has aesthetics and biocompatibility of zirconia abutment, but also has mechanical compatibility of pure titanium abutment.Objective:Nanostructured zirconia layer were coated on titanium abutment by plasma spraying method. Then the zirconia porcelain crowns were made. The characteristics of mechanical compatibility were evaluated by fracture strength test, chew simulation test and thermal load test. Which provide a theoretical basis for the clinical application of the material.Methods:One-part form pure titanium implants were made and were divided into A, B, C and D four groups according to the neck diameter. The diameter was 2.6mm,2.0mm,1.8mm and 1.6mm respectively. Among these, group A was the standard control group. The neck of implants of groups B, C and D were coated with nanostructured zirconia layer by plasma spraying method. Eventually, all of the neck diameter was 2.6mm. The upper zirconia porcelain crowns were completed according to the standard process. Then the fracture strength test and the artificial aging test were in progress. 1 The fracture strength test 6 one-part form pure titanium implants specimens were randomly selected in each group. The fracture strength test was in progress after the artificial aging test. While the control group was without the artificial aging test, 1mm double foil paper was placed between each specimen and loading head. The load of 1.5rnm/min,45°to the implant axis was uploaded to the crown by universal testing machine until the specimens cracking. Then record the corresponding data. The artificial aging test included chew simulation test and thermal load test. 2 The artificial aging test 6 implant-abutment-crown connection specimens in each group were fixed in the TCML for the fatigue experiment. The surface crack of material was observed. Whether cracked or broken of specimens appeared were observed. Then the fracture strength test were in progress after dismantling the upper crown.Result:All specimens after artificial aging test were not been cracked or broken. The cracked parts of specimens in the fracture strength test were all in the neck of abutments. The result of statistical analysis of the rupture force value of artificial aging and no artificial aging were shown in table 1. The force value of groups B, C and D were more than the daily chewing but significantly less than group A. There were statistical differences among the four groups.(Table 2) While before and after artificial aging, there were no statistical difference of four groups of specimens. (Table 3, Fig.1)Conclusion:The above experimental results showed that the mechanical compatibility of plasma sprayed nanostructure zirconia titanium specimen prepared by our group met the need of clinical application. It provides experimental basis for the further clinical application of this material. |
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