title: Fracture strength and failure mode of maxillary implant-supported provisional single crowns: a comparison of composite resin crowns fabricated directly over PEEK abutments and solid titanium abutments.
abstract: BACKGROUND
  Polyetheretherketone (PEEK) temporary abutments have been recently introduced for making implant-supported provisional single crowns. Little information is available in the dental literature on the durability of provisional implant-supported restorations.
  
  
  OBJECTIVE
  The objectives of this study were to evaluate the fracture strength of implant-supported composite resin crowns on PEEK and solid titanium temporary abutments, and to analyze the failure types.
  
  
  METHODS
  Three types of provisional abutments, RN synOcta Temporary Meso Abutment (PEEK; Straumann), RN synOcta Titanium Post for Temporary Restorations (Straumann), and Temporary Abutment Engaging NobRplRP (Nobel Biocare) were used, and provisional screw-retained crowns using composite resin (Solidex) were fabricated for four different locations in the maxilla. The specimens were tested in a universal testing machine at a crosshead speed of 1 mm/minute until fracture occurred. The failure types were analyzed and further categorized as irreparable (Type 1) or reparable (Type 2).
  
  
  RESULTS
  No significant difference was found between different abutment types. Only for the position of the maxillary central incisor, composite resin crowns on PEEK temporary abutments showed significantly lower (p < 0.05) fracture strength (95 ± 21 N) than those on titanium temporary abutments (1,009 ± 94 N). The most frequently experienced failure types were cohesive fractures of the composite resin crowns (75 out of 104), followed by screw loosening (18 out of 104). According to reparability, the majority of the specimens were classified as Type 1 (82 out of 104). Type 2 failures were not often observed (22 out of 104).
  
  
  CONCLUSIONS
  Provisional crowns on PEEK abutments showed similar fracture strength as titanium temporary abutments except for central incisors. Maxillary right central incisor composite resin crowns on PEEK temporary abutments fractured below the mean anterior masticatory loading forces reported to be approximately 206 N.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. h.j.santing@kchir.umcg.nl
authors.forename: Hendrik Jacob
authors.initials: HJ
authors.lastname: Santing
authors.forename: Henny J A
authors.initials: HJ
authors.lastname: Meijer
authors.forename: Gerry M
authors.initials: GM
authors.lastname: Raghoebar
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
mesh_terms: D001577:Benzophenones; D001863:Bone Screws; D003188:Composite Resins; D003442:Crowns; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D007659:Ketones; D008437:Maxilla; D008855:Microscopy, Electron, Scanning; D011092:Polyethylene Glycols; D011108:Polymers; D013499:Surface Properties; D014025:Titanium; D016896:Treatment Outcome
chemical_list: D001577:Benzophenones; D003188:Composite Resins; D007659:Ketones; D011108:Polymers; C113676:Solidex; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D014025:Titanium