title: Experimental research on the relationship between fit accuracy and fracture resistance of zirconia abutments.
abstract: OBJECTIVE
  The purpose of the study was to investigate the correlation between fit accuracy and fracture resistance of zirconia abutments, as well as its feasibility for clinical applications.
  
  
  METHODS
  Twenty self-made zirconia abutments were tested with 30 Osstem GSII implants. First, 10 Osstem GSII implants were cut into two parts along the long axis and assembled with the zirconia abutments. The microgaps between the implants and the zirconia abutments were measured under a scanning electron microscope. Second, the zirconia abutments were assembled with 20 un-cut implants and photographed before and after being fixed with a central screw of 30-Ncm torque. The dental films were measured by Digora for Windows 2.6 software. Then the fracture resistance of zirconia abutments was measured using the universal testing machine at 90°. All results were analyzed using SPSS13.0 software.
  
  
  RESULTS
  The average internal-hexagon microgaps between the implants and zirconia abutments were 19.38±1.34μm. The average Morse taper microgap in the implant-abutment interface was 17.55±1.68μm. The dental film showed that the Morse taper gap in the implant-abutment interface disappeared after being fixed with a central screw of 30-Ncm torque, and the average moving distance of the zirconia abutments to the implants was 0.19±0.02mm. The average fracture resistance of zirconia abutments was 282.93±17.28N. The internal-hexagon microgap between the implants and zirconia abutments was negatively related to the fracture resistance of the abutments (r1=-0.97, p<0.01). The Morse taper microgap in the implant-abutment interface was negatively related to the fracture resistance of the abutments (r2=-0.84, p<0.01).
  
  
  CONCLUSIONS
  The microgap between implant and abutment was negatively related to the fracture resistance of the abutment, while the internal-hexagon microgap has better correlation than the Morse taper microgap. The closure of microgap is helpful to improve the fracture resistance of zirconia abutments. The fracture resistance of zirconia abutments can satisfy the clinical application.
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Sui
authors.affiliation: Department of Stomatology, Qingdao Eighth People's Hospital, Qingdao, China.
authors.forename: Huasha
authors.initials: H
authors.lastname: Wei
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Dashan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Radiology Department, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Han
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Deng
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China.
authors.forename: Junjun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Oral and Maxillofacial Surgery, Affiliated Hospital, Qingdao University, Qingdao, China. Electronic address: yjjqd@126.com.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Yang
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010781:Photography / Q000379:methods; D019252:Radiography, Dental, Digital / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
keywords: Fit accuracy; Fracture resistance; Internal hexagon; Morse taper; Zirconia abutment