title: Soft tissue and crestal bone changes around implants with platform-switched abutments placed nonsubmerged at subcrestal position: a 2-year clinical and radiographic evaluation.
abstract: OBJECTIVE
  To evaluate crestal bone changes around implants with platform-switched abutments placed 1 mm subcrestally in a prospective clinical investigation.
  
  
  METHODS
  Forty consecutive systemically healthy patients (mean age ± standard deviation [SD], 55.2 ± 8.7 years) with one or more missing teeth were consecutively treated with 1-mm subcrestally positioned, platform-switched, tapered, full treated implants restored with coded abutments. A total of 58 implants were placed. Final restorations were delivered 4 to 8 months after implant insertion. Digital standardized periapical radiographs using customized film holders were obtained at the time of implant insertion, and at 12 and 24 months after final prosthesis placement. Marginal peri-implant bone levels were measured at the mesial and distal surfaces of each implant using digital image software.
  
  
  RESULTS
  All implants osseointegrated and were clinically stable at the 2-year follow-up. The cumulative survival rate was 100%. From implant insertion to the 2-year follow-up, the mean bone loss was 0.32 ± 0.37 mm. No significant differences related to sex, implant site, and bone density were observed. The mean midbuccal and interproximal soft tissue margin positions were 1.13 ± 0.5 mm and 1.15 ± 0.6 mm coronal to the prosthetic finish line, respectively.
  
  
  CONCLUSIONS
  There is limited clinical information regarding the amount of marginal bone loss around two-piece platform-switched implants placed at subcrestal positions. Results of this study suggest that platform switching and subcrestal location of the implant-abutment interface may be effective in reducing bone loss and in preserving esthetics around dental implants.
authors.forename: Mario
authors.initials: M
authors.lastname: Aimetti
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferrarotti
authors.forename: Giulia Maria
authors.initials: GM
authors.lastname: Mariani
authors.forename: Carlo
authors.initials: C
authors.lastname: Ghelardoni
authors.forename: Federica
authors.initials: F
authors.lastname: Romano
mesh_terms: D000328:Adult; D000368:Aged; D016301:Alveolar Bone Loss / Q000517:prevention & control; D000539:Alveolar Process / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015519:Bone Density / Q000502:physiology; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration / Q000502:physiology; D010519:Periodontium / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011446:Prospective Studies; D016300:Radiography, Bitewing; D016019:Survival Analysis
chemical_list: D015921:Dental Implants