Evaluation of load testing of postendodontic restorations in vitro: linear compressive loading, gradual cycling loading and chewing simulation.

This study introduces a modified dynamic testing mode with gradual load increase and examines whether this could be an alternative to customary methods of static loading or chewing simulation. Seventy-two extracted human maxillary root-canal-treated central incisors were randomly divided into six groups with 12 teeth each. Three groups were restored with titanium posts cemented with chemically curing resin cement. The other three groups were restored with glass-fiber posts cemented with dual-curing composite cement. All teeth were capped with full ceramic crowns. Both kinds of restoration were tested by linear compressive (static) loading, a modified gradual (cycling) dynamic loading, and by chewing simulation followed by static loading until failure occurred. The maximum load capacity was recorded. Statistical comparison showed that maximum load capacities of the same post material obtained from gradual dynamic loading did not differ significantly from that of linear compressive loading or of chewing simulation. In contrast, comparisons of different post materials under static loading resulted in significantly different load capacities. Dynamic testing with gradual load increase can be considered an economic alternative for chewing simulation, because it provides equivalent results. Both procedures, however, imply different conclusions than static loading with respect to post materials. Copyright 2005 Wiley Periodicals, Inc.