Objectives:The aim of this study was to determine the fracture strenghts of two metal-free fixed partial denture (FPD) materials (IPS Empress 2, Adoro-Vectris) in inlay-retained and full veneer retainer designs. Methods:50 mandibular premolar and 50 mandibular molar teeth were embedded into acrylic resin with two different span lengths (7 and 18 mm.). Five FPDs were constructed for each type of material with each span length and retainer design. Full veneer ceramo-metal FDPs with both span lengths were used as control groups. Metal-free FPDs were luted with a resin cement while ceramo-metal FDPs were cemented conventionally. FPDs were vertically loaded until fracture following the thermocycling process (5-55°C, 5000 times). Statistical analyses was performed using Variance Analysis and the Tukey's Multiple-Range Test. Results:Mean fracture resistances (N) and standard deviations of FPDs are shown in the following table :
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7 mm span length |
18 mm span length |
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Full veneer |
Inlay retained |
Full veneer |
Inlay retained |
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|
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|
IPS Empress 2 |
388.8 (61.4) |
480.6 (106.4) |
335.8 (44.9) |
404.0 (80.4) |
|
Adoro-Vectris |
1307.8 (217.9) |
1189.2 (199.0) |
1164.0 (158.0) |
1259.2 (241.5) |
|
Ceramo-metal |
3457.2 (277.3) |
* |
921.0 (176.6) |
* |
Type of material and span length exhibited a significant influence on fracture resistance regardless of the retainer type (P<0.05). Conclusions:Ceramo-metal FPDs of 7mm span length showed the highest mean fracture resistance. Adoro-Vectris fiber reinforced FPDs yielded higher fracture loads than IPS Empress FPDs, due to their high elastic moduli. IPS Empress 2 glass-ceramic FPDs exibited the lowest fracture resistance on both span lengths and each type of retainer.