title: Cemented and screw-retained implant-supported single-tooth restorations in the molar mandibular region: A retrospective comparison study after an observation period of 1 to 4 years.
abstract: OBJECTIVE
  The aim of this study was to evaluate the survival and compare the appearance of different mechanical and biological complications, in screw-retained and cemented-retained single-tooth implant-supported restorations localized in the molar mandibular region, over a period of 1 to 4 years.
  
  
  METHODS
  A retrospective study was carried out with a total of eighty implant-supported restorations, which were placed in eighty patients for prosthetic rehabilitation of a mandibular molar. Forty patients were rehabilitated with a cemented-retained restoration and the other forty with a screw-retained restoration. The presence of the following complications was recorded for both types of prostheses: Fractures of the ceramic veneering, loosening screws, mucositis and peri-implantitis. Debonding of the restoration was analyzed in the cemented-retained restoration group. The clinical survival of crowns was analyzed with a Kaplan-Meier test and the clinical complications were compared, using a Student t test and Log-rank test.
  
  
  RESULTS
  27 patients registered some complication. The average rate of complications was 37,5% for cemented-retained restorations and 30% for screw-retained restorations. The complications more common in the cemented-retained restoration were the presence of mucositis (14,87%), while in the screw-retained restorations was the loosening screw (20%). Student t test and Log-Rank test found significant differences (p=0,001) between the screw loosening and presence of mucositis.
  
  
  CONCLUSIONS
  The cemented-retained restorations seem to prevent screw loosening, but the presence of cement seem to increase the complications around the soft tissues, however in the screw-retained restorations the presence of mucositis and peri-implantitis are lower than cemented-retained restorations. The incidence of fracture of ceramic veneering was similar in both groups. Key words:Screw-retained restorations, cemented-retained restorations, screw loosening, peri-implant diseases and fracture ceramic veneering.
authors: DDS, PhD, Associate Professor of the Department of Buccofacial Prostheses. Faculty of Odontology. Complutense University of Madrid, Madrid, Spain.
authors: Alberto
authors: A
authors: Ferreiroa
authors: DDS, PhD, Chairman of Oral Surgery. Director of the Master in Oral Surgery and Implantology. Valencia University Medical and Dental School. Valencia, Spain. Investigator of the IDIBELL Institute.
authors: Miguel
authors: M
authors: Peñarrocha-Diago
authors: DDS, PhD, Professor and Director of the Department of Buccofacial Prostheses. Faculty of Odontology. Complutense University of Madrid, Madrid, Spain.
authors: Guillermo
authors: G
authors: Pradíes
authors: DDS, PhD, Adjunct Professor of the Occlusion and Prosthodontic Teaching Unit. Department of Stomatology. Valencia University Medical and Dental School. Valencia, Spain.
authors: María-Fernanda
authors: MF
authors: Sola-Ruiz
authors: DDS, PhD, Associate Professor of the Occlusion and Prosthodontic Teaching Unit. Department of Stomatology. Valencia University Medical and Dental School. Valencia, Spain.
authors: Rubén
authors: R
authors: Agustín-Panadero