title: Premature exposure of dental implant cover screws. A retrospective evaluation of risk factors and influence on marginal peri-implant bone level changes.
abstract: OBJECTIVE
  The objectives of this study were to identify risk factors associated with the premature cover screw exposure (pCSE) at dental implants and to evaluate the influence of a pCSE on peri-implant marginal bone level (MBL) change compared to non-exposed implants.
  
  
  METHODS
  Retrospective data assessment from 165 patients (mean age = 54.0 ± 14.4 years) who received 395 submerged implants included demographic, health-related, and therapeutic variables which were analyzed for their respective impact. MBL change was detected at digital radiographs obtained from first- and second-stage surgeries.
  
  
  RESULTS
  pCSE were detected in 43 patients (26.1%) and 53 implants (13.4%). An increased frequency of exposure was significantly associated with (I) male gender (p = 0.012) at patient level and (II) the posterior region of the jaws (p = 0.005), implant systems with platform-matching cover screws, and a vertical distance of ≥0.5 mm between bone crest and the implant platform (both p < 0.001) at implant level. The decrease in mesial, distal, and total MBL differed significantly (mean total = 0.8 ± 0.7 vs. 0.3 ± 0.5; mean mesial = 0.8 ± 0.8 vs. 0.3 ± 0.6; mean distal = 0.8 ± 0.8 vs. 0.3 ± 0.6 mm; p < 0.001) between non-exposed and pCSE implants.
  
  
  CONCLUSIONS
  Male patients, implants with platform-matched cover screws, or when placed supracrestally or in posterior sites revealed significantly more pCSE, resulting in significantly decreased peri-implant MBL compared with non-exposed implants.
  
  
  CONCLUSIONS
  Patients with an enhanced risk of pCSE should follow frequent regular recalls during the healing period to enable for early diagnosis and intervention.
authors.affiliation: Department of Oral Medicine, Dental Radiology, and Oral Surgery, Charité-Universitätsmedizin Berlin, Assmanshauser Str. 4-6, 14197, Berlin, Germany. moritz.hertel@charite.de.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hertel
authors.affiliation: Department of Oral Medicine, Dental Radiology, and Oral Surgery, Charité-Universitätsmedizin Berlin, Assmanshauser Str. 4-6, 14197, Berlin, Germany.
authors.forename: Yun-Chie
authors.initials: YC
authors.lastname: Roh
authors.affiliation: Institute of Medical Biometrics and Clinical Epidemiology, Charite-Universitätsmedizin Berlin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Neumann
authors.affiliation: Department of Oral Medicine, Dental Radiology, and Oral Surgery, Charité-Universitätsmedizin Berlin, Assmanshauser Str. 4-6, 14197, Berlin, Germany.
authors.forename: Frank Peter
authors.initials: FP
authors.lastname: Strietzel
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology*; D059605:Dental Implant-Abutment Design; D015921:Dental Implants / Q000009:adverse effects*; D017267:Dental Prosthesis Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019252:Radiography, Dental, Digital; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D015921:Dental Implants
keywords: Cover screw; Dental implant; Marginal peri-implant bone level change; Premature exposure