Valuation of simulation of anterior post and core restorations

Aim: In –vitro simulations were used for preclinical investigations of dental materials. The aim of this investigation was to compare the clinical survival rate of post and core anterior restorations with failures during in-vitro simulation to estimate a in-vivo : in-vitro correlation.

Materials and methods: 48 human upper incisors were provided with an artificial polyether (Impregum, 3M Espe) periodontium and embedded under 135°. The teeth were randomly divided into three groups (n=16) and restored with three different fibre-reinforced post systems: Dentin Post (Komet, G), FibreKor (Jeneric Pentron, USA) and Luscent Anchors (Dentatus, G). Eight specimens per group were thermally cycled and mechanically loaded in a first run (TCML 1: 12000x5°/55°, H₂O, 2 min. each cycle, 2.4*10⁶x25N, human antagonists) and the failure rates were compared to available clinical data from MEDLINE. In-vivo behaviour and in-vitro survival data were used for calculating a mathematical model and for adapting parameters of a second TCML run (TCML 2: 12000x5°/55°, H₂O, 2 min. each cycle, 2.4*10⁶x 50N, human antagonists). TCML survival rate was observed and all remaining restorations were loaded to fracture (Zwick 1446, Zwick, G, v=1mm/min, 135°). Statistics: Median (25%/75%); Mann Whitney U-test and Kaplan-Meier (α=0.05).

Results:

With increasing TCML force, the fracture resistance of the restorations was reduced and failure rate increased. With adapted parameters (TCML2) an identical fracture pattern after simulation and loading to fracture could be observed.

Conclusions: Within the limitation of this study established TCML parameters can be used for simulating clinical failures of anterior post and core restorations.