[Effect of filler content of composite resins on polymerization shrinkage measured by a video imaging apparatus (Acuvol)].
OBJECTIVE
To investigate the effect of filler content on the polymerization shrinkage of resins and to evaluate whether Acuvol is a simple and easy method in volumetric shrinkage measurement.


METHODS
Six experimental resins with filler contents of 80%, 78%, 76%, 70%, 60%, and 50% were made. Three commercial resins were Syn D6 with 80% filler content, Syn Compact Nano with 74% filler content and Syn Flow with 55% filler content(using the mass fraction to express the filler content). Small semi-sphere samples of these composites were manually formed and light cured for 40 s using a quartz tungsten halogen unit at 650 mW/cm2 (n=10). The volumetric shrinkage was measured in both SVVR and MVVR modes using Acuvol.


RESULTS
The volumetric shrinkage of the three commercial resins were: Syn Flow > Syn Compact Nano > Syn D6. The shrinkage values of the six experimental resins with different filler contents were: 50% > 60% > 70% > 76% > 78% > 80%. The negative correlation between filler content and volumetric shrinkage of commercial and experimental resins were strongly (-0.982 and -0.968 respectively, P<0.001). No significant difference between SVVR and MVVR modes (t=0.385, P>0.05).


CONCLUSIONS
The present results support the view that filler content is one of the most important factors influencing polymerization shrinkage of composites. Acuvol provides an easy method for measuring polymerization shrinkage of composites. Both SVVR and MVVR modes of Acuvol give reproducible results.
Department of Cariology, Endodontology and Operative Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Bing
B
Han
Yan-mei
YM
Dong
Xiao-yan
XY
Wang
Fu-cong
FC
Tian
Xue-jun
XJ
Gao
D000180:Acrylic Resins / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D058105:Polymerization; D011140:Polyurethanes / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry*; D014741:Video Recording
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D012117:Resins, Synthetic