title: Effect of connector design on fracture resistance of zirconia all-ceramic fixed partial dentures.
abstract: The purpose of the present study was to determine the relationship between cross-sectional design and fracture load using a static load bearing test in yttria-stabilized tetragonal zirconia polycrystal ceramic frameworks on a molar fixed partial denture. The test framework was designed as a 3-unit bridge with two abutment teeth at the second premolar and second molar of the mandible. The cross-sectional area of the connector was 9.0, 7.0, or 5.0mm(2). In terms of shape, the cross-section was either circular or oval, with a height/width ratio of 1:1, 3:4, or 2:3. For each of the 9 combinations of cross-sectional area and shape, 5 frameworks were prepared (45 in total). Frameworks were cemented to a metallic test model with adhesive resin cement. After fracture load was measured, the percentage of fracture sites was determined and the fracture surfaces observed. In terms of cross-sectional area, there was a statistically significant difference in fracture load between 9.0, 7.0, and 5.0mm(2). No significant difference in fracture load was observed between any two shapes of connector (p>0.05). The fracture load of all frameworks with a cross-sectional area of 9.0 or 7.0mm(2) was over 880 N, which was recognized as parafunctional occlusal force. Fracture occurred at the distal connector in 82.2% of all frameworks on average. Fracture load decreased as cross-sectional area of the connector became smaller. The cross-sectional shape used in the present study was less influential on fracture load. It appears to be clinical possible to apply a connector with a cross-sectional area of 7.0mm(2). Fracture often occurred at the distal connector between the pontic and the abutment, corresponding to the second molar.
authors.affiliation: Department of Crown and Bridge Prosthodontics, Tokyo Dental College.
authors.forename: Kozue
authors.initials: K
authors.lastname: Onodera
authors.forename: Toru
authors.initials: T
authors.lastname: Sato
authors.forename: Syuntaro
authors.initials: S
authors.lastname: Nomoto
authors.forename: Otoaki
authors.initials: O
authors.lastname: Miho
authors.forename: Mamoru
authors.initials: M
authors.lastname: Yotsuya
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D001732:Bite Force; D000044:Dental Abutments; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003779:Denture Design / Q000009:adverse effects*; D003781:Denture Retention / Q000295:instrumentation*; D003830:Denture, Partial, Fixed / Q000009:adverse effects*; D008963:Molar; D018709:Statistics, Nonparametric; D015019:Yttrium; D015040:Zirconium
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium