title: Screw- vs cement-implant-retained restorations: an experimental study in the Beagle. Part 1. Screw and abutment loosening.
abstract: The causes of implant failures can be biological or mechanical. The mechanical causes include fracture of the implant, fracture of the abutment, and loosening of the abutment. Numerous studies show that abutment loosening constitutes one of the marked implant postsurgery complications requiring clinical intervention. The aim of the present study was to evaluate the incidence of the screw loosening in screwed or cemented abutments. Six adult male Beagles were used. In each dog, the first molars and 2 premolars were extracted. The sutures were removed after 7 days. After 3 months, 10 implants were placed in each dog, 5 in the right mandible and 5 in the left mandible. The abutments either were screwed in (n=30) by applying a total strength of 30 N/cm or were cemented (n=30). After 12 months, 8 (27%) loosened screws were present in screwed abutments, whereas no abutment loosening was observed in cemented abutments (P = .0001). Screwed abutments are often submitted to nonaxial loads that determine screw and abutment loosening.
authors.affiliation: Dental School, University of Chieti-Pescara, Chieti, Italy.
authors.forename: Bartolomeo
authors.initials: B
authors.lastname: Assenza
authors.forename: Antonio
authors.initials: A
authors.lastname: Scarano
authors.forename: Giulio
authors.initials: G
authors.lastname: Leghissa
authors.forename: Giorgio
authors.initials: G
authors.lastname: Carusi
authors.forename: Ulf
authors.initials: U
authors.lastname: Thams
authors.forename: Fidel San
authors.initials: FS
authors.lastname: Roman
authors.forename: Adriano
authors.initials: A
authors.lastname: Piattelli
mesh_terms: D000818:Animals; D002484:Cementation; D000044:Dental Abutments; D017268:Dental Prosthesis Retention / Q000295:instrumentation / Q000379:methods*; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D004285:Dogs; D008297:Male