Microstructure and Properties of Resin Hybrid CAD/CAM Materials

Objectives: 

Compare the microstructure, strength, and hardness of resin hybrid CAD/CAM materials (see table).  VE has an interpenetrating network composite structure of feldspathic porcelain and polymer; LVU has nanoceramic particles (zirconia, silica, and zirconia-silica) reinforcing a polymer matrix. 

Methods: 

Tiles were cut to 1 mm thickness, polished, and imaged via SEM at 7 different locations.   Phase content was measured with Olympus™ StreamEssentials™ Image Analysis software using the “count & measure” tool and gray scale feature selection.  4mm diameter by 8mm long specimens were conditioned in deionized water at 37°C for 24hr prior to measuring compressive strength (CS) on an Instron™ machine.  Vickers hardness (Hv) was measured according to ASTM C1327-08 on mounted & polished specimens (n=10 indents).  Data were analyzed via ANOVA with Tukey's t-test (p<0.05).

Results: 

The table shows results, and groups that are statistically not different (SND).  Volume fraction ceramic and also volume percent polymer were statistically not different in VE and LVU.   CS of LVU was statistically higher than VE:  Hv of VE was statistically higher than LVU.    

Conclusions:  

Despite the similar ceramic/polymer content of LVU and VE, there are differences in strength and hardness, which might be attributed instead to differences in composition and microstructure.  In resin hybrid materials, the volume content ceramic might correlate to some properties, but others also depend on microstructure and composition.