title: Four-year follow-up of larger-diameter implants placed in fresh extraction sockets using a resorbable membrane or a resorbable alloplastic material.
abstract: OBJECTIVE
  The aim of this randomized study was to evaluate and compare the long-term success rates of cylindric, screw-type titanium implants with a larger diameter (5.9 mm) that were placed in fresh extraction sockets in association with resorbable bone substitutes or a resorbable membrane.
  
  
  METHODS
  Eighty-three partially edentulous adult patients, selected from among those treated in 1997 and 1998 at the San Raffaele Institute in whom 1 or more implants had been placed into fresh posterior mandibular or maxillary sockets, were included in the study. A total of 111 implants were placed, 36 in mandibles and 75 in maxillae. Fifty-six implants were placed in combination with resorbable hydroxyapatite (HA group) and 55 with a resorbable membrane (MR group). Intraoral radiographs and follow-up examinations, including verification of implant stability via the Periotest, were carried out at second-stage surgery 3, 6, 9, and 12 months later; and then annually up to 4 years after placement of the definitive restoration. The radiographic examination was conducted by means of a standardized procedure to verify osseointegration.
  
  
  RESULTS
  There was 100% attendance at the follow-up examination after 4 years. At second-stage surgery, which was performed after 4 to 6 months' healing time, none of the implants showed any signs of mobility, peri-implantitis, or bone loss. Two implants failed in the MR group, one at 3 months and one at 9 months after placement; 1 implant failed in the HA group at 4 months after placement. After 4 years, the implant success rate was 97.3% (108 of 111 implants were considered successful). The success rate did not differ significantly between the HA group (98.2%) and the MR group (96.4%).
  
  
  CONCLUSIONS
  The use of larger-diameter implants served to minimize the anatomic discrepancies that would have evolved when substituting a molar with a standard-diameter implant. According to the accepted criteria for success, the 5-year success rate should be at least 85%; therefore both methods may be considered satisfactory.
  
  
  CONCLUSIONS
  Implants placed in combination with a resorbable allogeneic material or with a resorbable membrane provided predictable long-term results when restored with a fixed partial denture.
authors.affiliation: Oral Rehabilitation Department, University Vita e Salute, Scientific Institute, San Raffaele Hospital, Milan, Italy. lorisprosper@tin.it
authors.forename: Loris
authors.initials: L
authors.lastname: Prosper
authors.forename: Enrico F
authors.initials: EF
authors.lastname: Gherlone
authors.forename: Sara
authors.initials: S
authors.lastname: Redaelli
authors.forename: Manlio
authors.initials: M
authors.lastname: Quaranta
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D000368:Aged; D018786:Bone Substitutes / Q000627:therapeutic use*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D017886:Durapatite / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000601:surgery; D008297:Male; D008334:Mandible / Q000601:surgery; D008437:Maxilla / Q000601:surgery; D008567:Membranes, Artificial; D008875:Middle Aged; D016348:Osseointegration; D014081:Tooth Extraction; D020390:Tooth Socket / Q000601:surgery*; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D015921:Dental Implants; D008567:Membranes, Artificial; D017886:Durapatite