Christian Mehl1, Klaus Ludwig, Martin Steiner, Matthias Kern. 1. Department of Prosthodontics, Propaedeutics and Dental Materials, Dental School, Christian-Albrechts University Kiel, Arnold-Heller-Strasse 16, 24105 Kiel, Germany. cmehl@proth.uni-kiel.de
Abstract
OBJECTIVES: The purpose of this in vitro study was to compare the centric and eccentric quasi-static and fatigue fracture strength of industrially prefabricated resin-bonded three-unit inlay-retained fixed dental prostheses (IPIRFDPs). The IPIRFDPs consisted of industrial manufactured yttria-stabilized tetragonal zirconia (Y-TZP) frameworks with an industrially added microhybrid composite veneering. METHODS: Identical IPIRFDP-models consisted of a second premolar, a missing first molar and a second molar (CoCrMo alloy) integrated in a low melting alloy base. Roots were covered with a soft silicone layer to simulate an artificial parodontium. Premolars had an occlusal-distal inlay-preparation and molars a mesial-occlusal inlay-preparation. Forty-two IPIRFDPs with a connector size of 9 mm(2) and a framework connector size of 4.7 mm(2) were cemented adhesively to the IPIRFDP-models. Quasi-static fracture strength was tested with centric (n=12) and eccentric (n=6) loading in a universal testing machine at a cross-head speed of 1 mm/min. Fatigue fracture strength was tested at 1200 N with centric loading (n=12) and at 600/500 N with eccentric loading (n=6) at a frequency of 0.5 Hz. Statistical comparison of groups was performed with the Mann-Whitney U test. RESULTS: Quasi-static fracture strength differed significantly between centric (1749 N) and eccentric loading (880 N, p<0.001). Mean loading cycles until fracture were 4432 for centric loading at 1200 N compared to only 3 and 410 loading cycles for eccentric loading at 600 and 500 N, respectively. SIGNIFICANCE: Considering the maximum chewing forces in the molar region, it seems clinically possible to use prefabricated IPIRFDPs with Y-TZP as a core material with a framework connector size of 4.7 mm(2).
OBJECTIVES: The purpose of this in vitro study was to compare the centric and eccentric quasi-static and fatigue fracture strength of industrially prefabricated resin-bonded three-unit inlay-retained fixed dental prostheses (IPIRFDPs). The IPIRFDPs consisted of industrial manufactured yttria-stabilized tetragonal zirconia (Y-TZP) frameworks with an industrially added microhybrid composite veneering. METHODS: Identical IPIRFDP-models consisted of a second premolar, a missing first molar and a second molar (CoCrMo alloy) integrated in a low melting alloy base. Roots were covered with a soft silicone layer to simulate an artificial parodontium. Premolars had an occlusal-distal inlay-preparation and molars a mesial-occlusal inlay-preparation. Forty-two IPIRFDPs with a connector size of 9 mm(2) and a framework connector size of 4.7 mm(2) were cemented adhesively to the IPIRFDP-models. Quasi-static fracture strength was tested with centric (n=12) and eccentric (n=6) loading in a universal testing machine at a cross-head speed of 1 mm/min. Fatigue fracture strength was tested at 1200 N with centric loading (n=12) and at 600/500 N with eccentric loading (n=6) at a frequency of 0.5 Hz. Statistical comparison of groups was performed with the Mann-Whitney U test. RESULTS: Quasi-static fracture strength differed significantly between centric (1749 N) and eccentric loading (880 N, p<0.001). Mean loading cycles until fracture were 4432 for centric loading at 1200 N compared to only 3 and 410 loading cycles for eccentric loading at 600 and 500 N, respectively. SIGNIFICANCE: Considering the maximum chewing forces in the molar region, it seems clinically possible to use prefabricated IPIRFDPs with Y-TZP as a core material with a framework connector size of 4.7 mm(2).
Authors: Manea M Al-Ahmari; Abdulrahman H Alzahrani; Feras A Al-Qatarneh; Mohammed M Al Moaleem; Mansoor Shariff; Saeed M Alqahtani; Amit Porwal; Fuad A Al-Sanabani; Thiyezen A AlDhelai Journal: Med Sci Monit Date: 2022-06-17