In vitro study of edge-strength of provisional polymer-based crown and fixed partial denture materials

To evaluate in vitro the edge-strength of polymer-based provisional crown and fixed partial denture materials at increasing distances from an edge.

Three dimethacrylate-based provisional crown and fixed partial denture materials (Protemp 3 Garant, Luxatemp, and fast set Temphase) and one monomethacrylate-based one (Trim) were selected. Seven disk-shaped specimens of 12mm in diameter and 2.5mm in thickness for each material were fabricated and stored at 37 degrees C and 80% relative humidity for 1 month. The edge-strength was measured by using a CK 10 testing machine at a distance of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0mm from the edge of the specimen. All experiments were carried out in triplicate at each distance at 23+/-1 degrees C. The data were statistically analyzed using one-way ANOVA and the multiple comparison Scheffé test at the significance level of 0.05.

Trim showed severe deformation without chipping during loading at all distances. Protemp 3 Garant showed indentation at over 0.8mm from the edge, and for Luxatemp and fast set Temphase over 0.6mm from the edge without chipping. At 0.5mm from the edge, the highest values (2073.7N) were displayed by Protemp 3 Garant, approximately three times those of fast set Temphase (767.3N) and Luxatemp (697.0N) (p<0.05). The strengths of fast set Temphase and Luxatemp were not significantly different (p>0.05). Linear regression between the distance from the edge to 0.7mm and strength values of Protemp 3 Garant produced a correlation coefficient, R=0.99.

The dimethacrylate-based provisional materials tested were stronger in edge-strength than the monomethacrylate-based one which showed severe deformation without fracture.