| With the increasing maturity of implanting technology, more and more patients with of dentition defects or loss would like to choose implant restoration. However, upper anterior tooth face enormous aesthetics challenges because of its high degree of visibility. Titanium abutments have good physical properties, but its dark gray metallic color and opacity will greatly reduce the transparency of porcelain which led to all-ceramic restorations dark and soft tissue changes may also result in late gingival sulcus titanium metal leakage. Zirconia abutments effectively overcome the aesthetic defect of titanium abutments, its unique aesthetic characteristics and good mechanical properties will greatly promote the development of aesthetic implantation. Given the aesthetic advantages of zirconia abutments and good osteogenesis of titanium implants, their combination will become a new trend in anterior region of implanting. However, Elasticity modulus of zirconia is about twice of titanium. Abutment connector by using the same materials of implant and abutment cannot be satisfied the implementation of new scheme because of great difference of mechanical property between zirconia and titanium. So redesigning the connector between implant and abutment is becoming an urgent clinically problem. To choose the design of the minimum stress in abutment and bone around implant, a method that based on finite element analysis was used for optimal design in the connection of titanium implant and zirconia abutment.The research consists of three parts: 1. Effects of stress distribution around abutment and implant-bone interface by different zirconia abutmentThrough optimizing five connection design of titanium implant and zirconia abutment by the three-dimensional finite element analysis method, we analyzed the effects of stress peak and distribution of alveolar bone by different designs of zirconia abutment connector. The results show that different connection designs will cause different stresses in abutment and bone. Hexagonal design will lead to the rise of stress in bone tissue. Clover design can reduce stress in the abutment, but did not reduce stress in bone tissue. Cylindrical zirconia abutments have smallest stress in both abutment and bone tissue, which is most conducive design to the protect abutment and bone tissue around the implant. 2. Effects of stress distribution around abutment and implant-bone interface by different tilted and high zirconia abutment.we constructed zirconia abutment with different angle(0°-30°) and height(1mm-6mm)based on cylindrical abutment through three-dimensional finite element analysis method. Then we analyzed the effects of different design in stress distribution around abutment and bone. The results indicated that different height and angle of zirconia abutments will result in different stress in zirconia abutments itself and the surrounding bone tissue. Increases gingival height and angle of zirconia abutment will increase stress in abutment itself and bone tissue. Compared with angle, zirconia abutments height more likely increase stress in zirconia abutments and bone around the implant. 3. Effects of stress distribution around abutment and implant-bone interface by zirconia abutment and titanium abutment.We constructed optimal design and relevant analysis to different categories of titanium abutment. The results indicated that with the increase of the angle and height of titanium abutment,the peak stress around cortical bone and titanium abutment showed an upward trend. As zirconia abutments, the most easy break position of titanium abutment is the neck of abutment. The abutment and bone stress of titanium abutments are higher than zirconia abutments in various heights and angle.In conclusion, apart from good aesthetic property of zirconia abutments, it also has good biomechanical properties which result in lower stress in abutment and bone compared with titanium abutments. Zirconia is good materials for dental implant abutment.Therefore, different form design of zirconia abutment had certain difference to zirconia abutment itself and stress around alveolar bone. In our study, we wish to provide certain reference significance in clinical design and application of zirconia abutment. |
