In Vitro Investigation Of The Mechanical And Biological Properties Of CAD/CAM Zirconia Custom Implant Abutment

With the improvement of living standards and medical level,more and more doctors and patients choose implant prostheses because of its beautiful、comfortable、no foreign body sensation and no damage to the adjacent teeth.However,as the number of implantation increased,the postoperative complications,led by peri-implantitis,have attracted the attention of many scholars and doctors.The implant abutment is an important part of the implant restoration system,its material,structure and suitability affect the stress distribution and biological properties of implant system,which is closely related to the occurrence and development of the surrounding inflammation.In this study,CAD/CAM zirconia custom implant abutment and Nobel finished abutment,which were commonly used in the Department of Stomatological Hospital of the Fourth Military University,were studied by three-dimensional finite element method、circled fatigue experiment and bacterial culture to analyse the mechanical and biological properties,in order to provide the necessary reference and basis.Part 1 In vitro investigation of the mechanical properties of CAD/CAM zirconia custom implant abutmentAIM: To evaluate the different stress distribution and influence between the CAD/CAM zirconia custom implant abutment and the finished titanium abutment.METHODS: Implant finite element models with CAD/CAM zirconia custom implant abutment and the titanium abutment were established according to ISO standard 14801,stress distribution was analysed using ANSYS software.Two groups(n=6)were assessed: group T,CAD/CAM zirconia custom implant abutment with Tibase grit blasted;group C,finished titanium abutment.Six implant abutments were secured to implants and embedded in autopolymerizing acrylic resin according to ISO standard 14801.After 5℃-55 ℃ circled fatigue experiment,representative specimens were examined using stereomicroscopy and scanning electron microscopy to observe the gap between the components.RESULTS: Implant with CAD/CAM zirconia custom abutment had stress concentration at the connection of zirconia abutment and Tibase,and the peak stress were higher than implant with titanium abutment.The gaps in implant with CAD/CAM zirconia custom abutment were larger(P<0.05).After circled fatigue experiment,the gaps in implant with CAD/CAM zirconia custom abutment were much larger than implant with titanium abutment.CONCLUTION: From the perspective of the stress analysis and the gap between the components,the finished titanium abutment is superior to CAD/CAM zirconia custom implant abutment.Part 2 In vitro investigation of the biological performance of CAD/CAM zirconia custom implant abutmentAIM: To compare the adhesion and colonization of the Streptococcus mutans in the gaps of the CAD/CAM zirconia custom implant abutment and the finished titanium abutment.METHODS: Culture and observation of bacteria around the implant: The assembled individualized porcelain-based abutment and finished abutment implants were cultured in UA159(Streptococcus mutans)at a concentration of 107 CFU / ml for 24 hours and then rinsed 10 times with distilled water,the bacteria were adhered with the 5% glutaraldehyde for 12 h,and the bacterial adhesion was observed by scanning electron microscopy.Quantitative comparison of bacteria around implants : Select the assembled individualized porcelain-based abutment and finished abutment implants after fatigue loading(n=3),cultured in UA159(Streptococcus mutans)at a concentration of 107 CFU / ml for 24 hours.And then collected bacteria within the implant gap into the solid medium,cultured 24 h,and observe the number of colonies within the solid medium.The experiment was repeated three times,and the data were recorded and analyzed statistically.RESULTS: Compared with the implant with finished abutment,the individualized porcelain-based abutment implants appeared more densely distributed.The number of colonies of group C was significantly lower than that of group TC(P <0.05).There was no significant difference between the group C and group TZ(P> 0.05).CONCLUTION: Streptococcus mutans can colonize in the gap between the components.Bacteria is more intensive in the individualized porcelain-based abutment implant.The number of colonies obtained from the individualized porcelain-based abutment was significantly higher than that of the finished base implant.