Screw- vs Cement-implant–retained Restorations: An Experimental Study in the Beagle. Part 1. Screw and Abutment Loosening
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.Abstract
Contributor Notes
Bartolomeo Assenza, MD, DDS, is a visiting professor and Antonio Scarano, DDS, MD, is a researcher in the Dental School, University of Chieti-Pescara, Chieti, Italy
Giulio Leghissa, MD, DDS, has a private practice in Milano, Italy
Giorgio Carusi, MD, DDS, is a visiting professor University of Pisa, Pisa, Italy
Ulf Thams, MD, DDS, has a private practice, in Madrid, Spain
Fidel San Roman, MD, is director of Veterinary Teaching Hospital, Complutense University, Madrid, Spain
Adriano Piattelli, MD, DDS, is a professor of Oral Medicine and Pathology, Dental School, University of Chieti-Pescara. Address correspondence to Dr Piattelli at Via F. Sciucchi 63, 66100 Chieti, Italy (apiattelli@unich.it)