| BackgroundMaxillofacial defects caused by tumor or trauma often lead to physiological functional and psychological problems. Maxillofacial prosthesis is an effective practice to rehabilitate the defects functionally and aesthetically. But the traditional prostheses are large, heavy and low elasticity, which not only affects the rention and normal physical properties, but also can not meet the request of the complex defects. Nowadays, the MDX4-4210biomedical grade elastomer is widely used for restoring missing facial structures due to its superior performance, while titanium mesh is also applied in the cranial and maxillofacial restoration because of qualitative light, high strength and good biocompatibility. So using titanium mesh as internal stent and using silicone rubber materials as outer coat, with the help of CAD/CAM and Rapid Shaping Technology, to develop a maxillofacial prosthesis of qualitative light and good retention would have an important clinical significance.However, the mechanical properties of titanium mesh are depending on its diameter and thickness, which affects its application in clinical. Meanwhile, the hollow structure of titanium mesh would lead to difficult combination with silicone rubber, especially when the defects are complex. So the bonding strength between silicone rubber and titanium mesh is particularly important. Weaking bonding between them is apt to separation, which lead to the prosthesis out of shape and increase the patient’s uncomfortable. What’s more, the edge stripped and poor retention would result in the frail bonding. So as to obtain high elasticity, high shape stability of the prosthetid material, it is critical to assess the bonding performance between the silicon rubber and titanium mesh and select the specifications of the titanium mesh.ObjectivesThis study is one part of the studies on the preparation of a new silicone rubber-titanium mesh prosthetic material. The aim of this study was to evaluate the bonding strength between the silicone rubber and titanium mesh and select the specifications of the titanium mesh. It is the first stage of fabricating a maxillofacial prosthesis of qualitative light and good retention by means of CAD/CAM and Rapid Shaping Technology.Materials and MethodsPart Ⅰ:42silicone rubber-cast titanium specimens were preparated, randomly divided into6groups (n=7) respectively according to the different processing of the surface of titanium mesh. Group A:polish+Permabond731, Group B:polish+sandblasting+Permabond731, Group C:polish+sandblasting+Permabond POP+Permabond731, Group D:polish+Permabond4C10, Group E:polish+sandblasting+Permabond4C10, Group F:polish+sandblasting+Permabond POP+Permabond4C10. According to the standard GB/T13936-92, shear bond tests were carried out at room temperature by using a universal testing machine. And the failure modes of the debonding specimens were observed with optical microscope.30silicone rubber-titanium mesh specimens were preparated, randomly divided into6groups (n=5) respectively according to the different processing of the surface of titanium mesh. The experiments group was similar to the shear bond strength. According to the standard GB/T7760-2003to take the90degrees peel strength test. And the failure modes of the debonding specimens were observed with optical microscope.Part IIThe titanium mesh were fabricated in diameter of3.0mm,4.0mm,5.0mm respectively(n=7). Then the surface was polishing, sand blasting, coating Permabond POP and Permabond4C10adhesive, and then bonding with the silicone rubber. The samples were mounted in the universal testing machine to take the shear bond strength test.The titanium mesh were fabricated in diameter of3.0mm,4.0mm with the thickness of0.4mm,0.6mm,0.8mm. According to the specification of the titanium mesh, there were6groups included(n=5). Then the titanium mesh were bonded with the silicone rubber, mounted in the universal testing machine to carry the three-point bending test at the loading speed of1mm/min.Part IIIAccording to the GB/T16886.12-2005, the cell toxicity test was used to investigate the biocompatibility of silicone rubber-cast titanium materials.Datas were analyzed by One-Way ANOVA and Two-Way ANOVA (SPSS13.0). Statistical significance was set at the0.05probability level (a=0.05).Results1. The shear bond strength test showed that there were significant difference among different treatments(P<0.05). The shear bond strength of Group C (1.98±0.14 MPa) was higher than Group B (0.26±0.11MPa) and Group A (0.17±0.08MPa)(P<0.05). The different adhesive also have the significant differences (P<0.05). Permabond4C10was higher than Permabond731(P<0.05). There were interaction effect between adhesive and treatment(P<0.05), the sandblasting followed by silane coupling agent and then bonded with Permabond4C10owned the highest shear bond strength.2. The result of peel strength test was similar to the shear bond strength. There were significant differences among different treatments(P<0.05), as well as the different adhesive. Sandblasting followed by silane coupling agent was higher than the sandblasting only(P<0.05). There were interaction effect between adhesives and treatments(P<0.05).3. The shear bond strength test of different mesh diameter showed that the group of3.0mm and4.0mm were higher than the5.0mm group (P<0.05). There was no significant difference between the group3.0mm(2.71±0.25MPa) and4.0mm (2.58±0.16MPa)(P>0.05).4. The three-point bending test of different diameter and thickness showed that the group of0.8mm has the highest bending strength than the0.6mm and0.4mm groups in the diameter of3.0mm, which was similar to the groups in the diameter of4.0mm(P<0.05). There were significantly differences between the groups in the diameter of3.0mm and4.0mm(P<0.05).5. The cell toxicity test showed that the cytotoxicity of silicone rubber-titanium material was grade1.Conclusion1. The Permabond4C10and Permabond731can achieve good bonding between titanium mesh and silicone rubber, which is better than that of Permabond731.2. The sand blasting followed by coupling agent is an effective way of surface treatment of titanium mesh, which can significantly improve the bonding strength. 3. The titanium mesh in the diameter of3.0mm with the thickness of0.6mm and0.8mm as well as4.0mm in diameter with the thickness of0.6mm and0.8mm, can satisfy the clinical needs. It is appropriate to choose the suitable specification according to the size of the defect in the clinical.4. The cytotoxicity of the silicone rubber-titanium mesh composite material is within the range of the clinical acceptable, which is a relatively safe biological materials. However, the clinical safety of this material is still need to be further in-depth study.Overall, although further research need to be done, this study is preliminary screened the treatment of titanium mesh surface and appropriate specifications, achieved the good bonding between silicone rubber and titanium mesh with no cytotoxicity, which laid the foundation for the subsequent experiments. |
PDF Full Text Request