IADR Abstract Archives
EVALUATION OF THE FRACTURE RESISTANCE OF CAD/CAM MONOLITHIC CROWNS THAT PREPARED WITH DIFFERENT CEMENT THICKNESSES
Objectives: The purpose of this study was to evaluate the fracture resistance of monolithic CAD/CAM crowns that prepared with different cement thicknesses.
Methods: A human maxillary premolar tooth selected for this investigation. Master model preparation was performed with a diamond bur under water spray. Impression from master die was taken to fabricate 105 epoxy resin replicas. The crowns were milled using a CEREC 4 CAD/CAM system.(Software Version, 4.2.0.57192) CAD/CAM crowns made with resin nanoceramic, feldspathic, lithium disilicate and leucite reinforced glass-ceramics. Each group subdivided into three groups in accordance with three different cement thicknesses (30, 90, 150 µm) (n=7). Then RelyXTM U200 was used as a luting agent to bond the crowns to the prepared samples. One hour after cementations, the speciemens were stored in water bath at 37 °C for 1 week prior to testing. Seven intact teeth were kept and tested as control group. A universal testing machine was used to assume the fracture resistance tests of all specimens. The compressive load was centered on the central groove of each crown, so that the load was applied to the triangular ridges of both fasial and palatal cusps. The compressive load (N) required for fracture was recorded for each speciemen. Fracture resistance data were statistically analyzed with one way ANOVA and two factor with interaction modellling tests (α=0.001)
Results: The highest mean fracture resistance value was recorded for IPS e.max CAD (1390.327 N), and the lowest value was recorded for IPS Empres CAD (787.988 N). There were statistically significant differences among the fracture resistance of CAD/CAM monolithic crowns (p<0.001); however, it was observed that the effect of cement thicknesses on the fracture resistance was not statistically significant. (p>0.001)
Conclusions: CAD/CAM monolithic crown materials influence fracture resistance. Cement thicknesses (30,90,150 µm) did not influence fracture resistance of CAD/CAM monolithic crowns.
Methods: A human maxillary premolar tooth selected for this investigation. Master model preparation was performed with a diamond bur under water spray. Impression from master die was taken to fabricate 105 epoxy resin replicas. The crowns were milled using a CEREC 4 CAD/CAM system.(Software Version, 4.2.0.57192) CAD/CAM crowns made with resin nanoceramic, feldspathic, lithium disilicate and leucite reinforced glass-ceramics. Each group subdivided into three groups in accordance with three different cement thicknesses (30, 90, 150 µm) (n=7). Then RelyXTM U200 was used as a luting agent to bond the crowns to the prepared samples. One hour after cementations, the speciemens were stored in water bath at 37 °C for 1 week prior to testing. Seven intact teeth were kept and tested as control group. A universal testing machine was used to assume the fracture resistance tests of all specimens. The compressive load was centered on the central groove of each crown, so that the load was applied to the triangular ridges of both fasial and palatal cusps. The compressive load (N) required for fracture was recorded for each speciemen. Fracture resistance data were statistically analyzed with one way ANOVA and two factor with interaction modellling tests (α=0.001)
Results: The highest mean fracture resistance value was recorded for IPS e.max CAD (1390.327 N), and the lowest value was recorded for IPS Empres CAD (787.988 N). There were statistically significant differences among the fracture resistance of CAD/CAM monolithic crowns (p<0.001); however, it was observed that the effect of cement thicknesses on the fracture resistance was not statistically significant. (p>0.001)
Conclusions: CAD/CAM monolithic crown materials influence fracture resistance. Cement thicknesses (30,90,150 µm) did not influence fracture resistance of CAD/CAM monolithic crowns.