title: Technical and biological complications related to crown to implant ratio: a systematic review.
abstract: OBJECTIVE
  To review the occurrence of prosthetic failure and biological complications with respect to the crown to implant (C/I) ratio.
  
  
  METHODS
  Accurate search was made on the subject C/I ratio with the following criteria: (1) studies on humans with data on prosthetic failure and/or biological complications related to C/I ratio; (2) partial edentulous patients; (3) randomized clinical trials, prospective, longitudinal, retrospective, and multicenter studies with a minimum of 48 months mean follow-up; (4) language: English; (5) radiographic measurements by peri-apical x-ray; (6) implant material: titanium; and (7) no implant type selection was applied.
  
  
  RESULTS
  Six articles were considered eligible for full-text analysis. Unfavorable C/I ratio can be considered a potential risk factor for single crown and abutment loosening (C/I ratio ≥ 1.46) and abutment fractures in posterior areas (C/I ratio ≥ 2.01).
  
  
  CONCLUSIONS
  Despite the limited data, high C/I ratio may be related to some prosthetic failures. Unfavorable C/I ratio does not affect biological complications and implant failure.
authors.affiliation: *Adjunct Professor, School of Dentistry, Universita' Politecnica delle Marche, Ancona, Italy. †Associate Professor and Director of the Master in Periodontics, School of Dentistry, Universita' Politecnica delle Marche, Ancona, Italy. ‡Associate Professor, Universita' Politecnica delle Marche, Ancona, Italy. §Full Professor and Dean of School of Dentistry, Universita' Politecnica delle Marche, Ancona, Italy. ‖Associate Professor, Director, Post-Graduate Program in Oral Surgery, Universita' Federico II, Napoli, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Quaranta
authors.forename: Matteo
authors.initials: M
authors.lastname: Piemontese
authors.forename: Giorgio
authors.initials: G
authors.lastname: Rappelli
authors.forename: Gilberto
authors.initials: G
authors.lastname: Sammartino
authors.forename: Maurizio
authors.initials: M
authors.lastname: Procaccini
mesh_terms: D003442:Crowns / Q000009:adverse effects; D000044:Dental Abutments / Q000009:adverse effects; D015921:Dental Implants / Q000009:adverse effects; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects / Q000379:methods; D019232:Dental Restoration Failure / Q000706:statistics & numerical data; D006801:Humans
chemical_list: D015921:Dental Implants