PURPOSE: The purpose of this study was to examine, in a controlled environment, effects of connection design upon screw stability. Implant fixtures have 2 types of connections to the abutment: internal connection and external hex. Four implant systems were tested: Bio-Lok (external hex; Bio-Lok International, Inc., Deerfield Beach, FL); Zimmer (internal connection; Zimmer Dental, Carlsbad, CA); Nobel Biocare (external hex; Nobel Biocare USA, Inc., Yorba Linda, CA); and Astra Tech (internal connection; Astra Tech Inc., Waltham, MA). MATERIALS AND METHODS: Ten samples of each system, including base, implant, abutment, and molar crown, were loaded to 200 N for 1 x 10(6) cycles. Screws were tightened to manufacturers' recommendations,and torque audits done at 2.5 x 10(5), 5 x 10(5), 7.5 x 10(5), and 1 x 10(6) cycles. RESULTS: The Bio-Lok samples lost an average of 10% of the original torque values, the Astra Tech group lost almost all of the torque and loosened, while the Zimmer and Nobel Biocare samples lost an average of 50% of the torque but did not loosen (P <or= 0.05). CONCLUSIONS: It may be concluded from this study that although internal connections are clinically favored, this study did not show any advantage relative to screw loosening. However, screw design may be a significant factor in loosening of the joint.
PURPOSE: The purpose of this study was to examine, in a controlled environment, effects of connection design upon screw stability. Implant fixtures have 2 types of connections to the abutment: internal connection and external hex. Four implant systems were tested: Bio-Lok (external hex; Bio-Lok International, Inc., Deerfield Beach, FL); Zimmer (internal connection; Zimmer Dental, Carlsbad, CA); Nobel Biocare (external hex; Nobel Biocare USA, Inc., Yorba Linda, CA); and Astra Tech (internal connection; Astra Tech Inc., Waltham, MA). MATERIALS AND METHODS: Ten samples of each system, including base, implant, abutment, and molar crown, were loaded to 200 N for 1 x 10(6) cycles. Screws were tightened to manufacturers' recommendations,and torque audits done at 2.5 x 10(5), 5 x 10(5), 7.5 x 10(5), and 1 x 10(6) cycles. RESULTS: The Bio-Lok samples lost an average of 10% of the original torque values, the Astra Tech group lost almost all of the torque and loosened, while the Zimmer and Nobel Biocare samples lost an average of 50% of the torque but did not loosen (P <or= 0.05). CONCLUSIONS: It may be concluded from this study that although internal connections are clinically favored, this study did not show any advantage relative to screw loosening. However, screw design may be a significant factor in loosening of the joint.
Authors: Ana Sofia Vinhas; Carlos Aroso; Filomena Salazar; Marta Relvas; Ana Cristina Braga; Blanca Ríos-Carrasco; Javier Gil; José Vicente Rios-Santos; Ana Fernández-Palacín; Mariano Herrero-Climent Journal: Materials (Basel) Date: 2022-02-14 Impact factor: 3.623
Authors: Cleide Gisele Ribeiro; Maria Luiza Cabral Maia; Susanne S Scherrer; Antonio Carlos Cardoso; H W Anselm Wiskott Journal: J Appl Oral Sci Date: 2011-07-01 Impact factor: 2.698
Authors: Ana Sofia Vinhas; Carlos Aroso; Filomena Salazar; Paula López-Jarana; José Vicente Ríos-Santos; Mariano Herrero-Climent Journal: Int J Environ Res Public Health Date: 2020-11-23 Impact factor: 3.390