title: Undetected residual cement on standard or individualized all-ceramic abutments with cemented zirconia single crowns - a prospective randomized pilot trial.
abstract: OBJECTIVE
  To assess the frequency and amount of residual cement after attachment of monolithic zirconia crowns to standard and individualized ceramic abutments.
  
  
  METHODS
  Twenty patients (mean age 58.9 years at inclusion in the study; 30% male) were randomized to receive either a standard or an individualized abutment on a bone-level implant. Monolithic zirconia single crowns were attached to abutments by use of permanent glass-ionomer cement. Crowns were fabricated with an occlusal hole to enable unscrewing of the abutment-crown complex. Immediately after cementation, superstructures were removed and both the peri-implant soft tissue and the abutment-crown complex were photographed in a standardized manner, to detect residual cement. Photographs were analyzed using Corel Photo Paint X7, and residual cement-to-total abutment and residual cement-to-peri-implant soft tissue area ratios were calculated.
  
  
  RESULTS
  Residual cement was observed for 9 of 10 (90%) individualized abutments, compared with 4 of 10 (40%) standard abutments (OR = 13.5, P = 0.049). Twenty-seven of 40 (68%) individualized abutment surfaces were affected, compared with 12 of 40 (30%) standard abutment surfaces. The probability of observing residual cement was approximately five times higher for the surfaces of individualized abutments than for those of standard abutments (P = 0.005). The mean amount of sulcus surface covered by cement was 1.17% (SD 2.85) for the individualized abutments and 3.78% (SD 7.40) for the standard abutments. The position of the margin significantly affected the amount of residual cement.
  
  
  CONCLUSIONS
  Both individualized and standard all-ceramic abutments result in small amounts of subgingival residual cement on abutment and sulcus surfaces. However, use of individualized abutments does not guarantee complete avoidance of undetected cement rests. Undetected residual cement might be avoided by use of all-ceramic abutments with visible abutment shoulders.
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kappel
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Eiffler
authors.affiliation: Institute for Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Justo
authors.initials: J
authors.lastname: Lorenzo-Bermejo
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stober
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Rammelsberg
mesh_terms: D002516:Ceramics / Q000627:therapeutic use*; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003764:Dental Materials / Q000627:therapeutic use*; D019094:Dental Prosthesis, Implant-Supported; D005260:Female; D005899:Glass Ionomer Cements / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D023861:Photography, Dental; D010865:Pilot Projects; D011446:Prospective Studies; D015040:Zirconium / Q000627:therapeutic use*
chemical_list: D003764:Dental Materials; D005899:Glass Ionomer Cements; D015040:Zirconium; C028541:zirconium oxide
keywords: abutments; all-ceramic; dental implants; residual cement