Objective   To test the fracture loading of extracted cracked teeth with CEREC CAD/CAM ceramic inlays/onlays.     Methods   All the extracted teeth were divided into two groups (A: control group; B: test group; n=15 teeth in each group). All the teeth were prepared into those imitating cracked teeth. Those teeth in group B were strengthened with CEREC CAD/CAM ceramic inlays/onlays. All teeth were thermocycled and mounted for testing and then were loaded until fracture.     Results   The force of anti-fracture of extracted teeth imitating cracked teeth with CEREC CAD/CAM ceramic inlays/onlays (group B) was obviously higher than that of the teeth without CEREC CAD/CAM ceramic inlays/onlays (group A).     Conclusion   CEREC CAD/CAM ceramic inlays/onlays can effectively prevent the crack of teeth in clinical practice.