PURPOSE: Chipping within veneering porcelain has resulted in high clinical failure rates for implant-supported zirconia (yttria-tetragonal zirconia polycrystals [Y-TZP]) bridges. This study evaluated the reliability and failure modes of mouth-motion step-stress fatigued implant-supported Y-TZP versus palladium-silver alloy (PdAg) three-unit bridges. MATERIALS AND METHODS: Implant-abutment replicas were embedded in polymethylmethacrylate resin. Y-TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact-tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step-stress profiles and mouth-motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. RESULTS: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y-TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two-sided at 90% confidence intervals) for a "mission" of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y-TZP. CONCLUSIONS: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials.
PURPOSE: Chipping within veneering porcelain has resulted in high clinical failure rates for implant-supported zirconia (yttria-tetragonal zirconia polycrystals [Y-TZP]) bridges. This study evaluated the reliability and failure modes of mouth-motion step-stress fatigued implant-supported Y-TZP versus palladium-silver alloy (PdAg) three-unit bridges. MATERIALS AND METHODS: Implant-abutment replicas were embedded in polymethylmethacrylate resin. Y-TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact-tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step-stress profiles and mouth-motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. RESULTS:PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y-TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two-sided at 90% confidence intervals) for a "mission" of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y-TZP. CONCLUSIONS: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials.
Authors: Christian F J Stappert; Marta Baldassarri; Yu Zhang; Felix Hänssler; Elizabeth D Rekow Journal: Clin Oral Implants Res Date: 2011-09-05 Impact factor: 5.977
Authors: Erika O Almeida; Amilcar C Freitas Júnior; Estevam A Bonfante; Nelson R F A Silva; Paulo G Coelho Journal: Lasers Med Sci Date: 2012-07-28 Impact factor: 3.161
Authors: Ronaldo Hirata; Estevam A Bonfante; Rodolfo B Anchieta; Lucas S Machado; Gileade Freitas; Vinicius P Fardin; Nick Tovar; Paulo G Coelho Journal: Clin Oral Investig Date: 2015-11-03 Impact factor: 3.573