[The mechanical loading capacity of new all-ceramic crown and bridge materials]

The present contribution presents the fracture toughness KIc, the bending strength and the splitting tensile strength of the recently developed all ceramics Cerec, Dicor, Duceram, IPS-Empress, Flexo-Ceram, Hi-Ceram, In-Ceram, LFC, Mirage (I, II), Optec HSP, Syntho-Ceram and Vitadur. The toughness of those materials suitable for crowns and bridges were also tested with the help of the "Normkronentest" on incisor and canine abutments made from natural teeth or Wiron alloy. As a consequence of our investigations we propose a differentiation into three classes of toughness: class I (fracture toughness up to 2.0 MPa*m1/2, fracture stress up to 100 MPa) consists of the leucite, mica or whisker strengthened ceramics Cerec, Dicor, Duceram, IPS-Empress, Flexo-Ceram, LFC, Mirage (I, II), Optec HSP and Vitadur Alpha, N. Dicor and Optec HSP are at the upper boundary. Class II (fracture toughness up to 3.0 MPa*m1/2, fracture stress up to 150 MPa) consists of the aluminium oxid strengthened ceramics Hi-Ceram, Syntho-Ceram and Vitadur N Kern. Class III (fracture toughness more than 3.0 MPa*m1/2, fracture stress more than 150 MPa) up to now consists only of the infiltration ceramics In-Ceram.