title: Two-body wear comparison of zirconia crown, gold crown, and enamel against zirconia.
abstract: OBJECTIVE
  Full zirconia crowns have recently been used for dental restorations because of their mechanical properties. However, there is little information about their wear characteristics against enamel, gold, and full zirconia crowns.
  
  
  OBJECTIVE
  The purpose of this study was to compare the wear rate of enamel, gold crowns, and zirconia crowns against zirconia blocks using an in vitro wear test.
  
  
  METHODS
  Upper specimens were divided into three groups: 10 enamels (group 1), 10 gold crowns (group 2, Type III gold), and 10 zirconia crowns (group 3, Prettau(®)Zirkon 9H, Zirkonzahn, Italy). Each of these specimens was wear tested against a zirconia block (40×30×3mm(3)) as a lower specimen (30 total zirconia blocks). Each specimen of the groups was abraded against the zirconia block for 600 cycles at 1Hz with 15mm front-to-back movement on an abrading machine. Moreover, the load applied during the abrading test was 50N, and the test was performed in a normal saline emulsion for 10min. Three-dimensional images were taken before and after the test, and the statistical analysis was performed using the Krushal-Wallis test and Mann-Whitney test (p=0.05).
  
  
  RESULTS
  The mean volume loss of group 1 was 0.47mm(3), while that of group 2 and group 3 was 0.01mm(3).
  
  
  CONCLUSIONS
  The wear volume loss of enamels against zirconia was higher than that of gold and zirconia crowns. Moreover, according to this result, zirconia crowns are not recommended for heavy bruxers.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Kyungpook National University, South Korea.
authors.forename: Min-Seok
authors.initials: MS
authors.lastname: Kwon
authors.affiliation: School of Automotive Engineering, Kyungpook National University, South Korea. Electronic address: syoh@knu.ac.kr.
authors.forename: Sang-Yeob
authors.initials: SY
authors.lastname: Oh
authors.affiliation: Department of Prosthodontics, School of Dentistry, Kyungpook National University, South Korea. Electronic address: sungamcho@gmail.com.
authors.forename: Sung-Am
authors.initials: SA
authors.lastname: Cho
mesh_terms: D003442:Crowns; D003743:Dental Enamel; D006046:Gold; D006801:Humans; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D015040:Zirconium
chemical_list: D006046:Gold; D015040:Zirconium; C028541:zirconium oxide
keywords: Enamel; Fixed partial dentures; Wear; Zirconia