title: The effect of resin cements and primer on retentive force of zirconia copings bonded to zirconia abutments with insufficient retention.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effect of resin cements and primer on the retentive force of zirconia copings bonded to zirconia abutments with insufficient retention.
  
  
  METHODS
  Zirconia blocks (Lava, 3M ESPE, St. Paul, MN, USA) were obtained and forty sets of zirconia abutments and copings were fabricated using CAD/CAM technology. They were grouped into 4 categories as follows, depending on the types of resin cements used, and whether the primer is applied or not:Panavia F2.0 (P), Panavia F2.0 using Primer (PRIME Plus, Bisco Inc, Schaumburg, IL, USA) (PZ), Superbond C&B (S), and Superbond C&B using Primer (SZ). For each of the groups, the cementation was conducted. The specimens were kept in sterilized water (37℃) for 24 hours. Retentive forces were tested and measured, and a statistical analysis was carried out. The nature of failure was recorded.
  
  
  RESULTS
  The means and standard deviations of retentive force in Newton for each group were 265.15 ± 35.04 N (P), 318.21 ± 22.24 N (PZ), 445.13 ± 78.54 N (S) and 508.21 ± 79.48 N (SZ). Superbond C&B groups (S & SZ) showed significantly higher retentive force than Panavia F2.0 groups (P & PZ). In Panavia F2.0 groups, the use of primer was found to contribute to the increase of retentive force. On the other hand, in Superbond C&B groups, the use of primer did not influence the retention forces. Adhesive failure was observed in all groups.
  
  
  CONCLUSIONS
  This study suggests that cementation of the zirconia abutments and zirconia copings with Superbond C&B have a higher retentive force than Panavia F2.0. When using Panavia F2.0, the use of primer increases the retentive force.
authors.affiliation: Department of Dentistry, School of Medicine Inha University, Incheon, Republic of Korea.
authors.forename: Seung-Mi
authors.initials: SM
authors.lastname: Kim
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Yoon
authors.forename: Myung-Hyun
authors.initials: MH
authors.lastname: Lee
authors.forename: Nam-Sik
authors.initials: NS
authors.lastname: Oh
keywords: Primer; Resin cement; Retentive force; Zirconia abutment; Zirconia coping