J Korean Acad Conserv Dent.  2008 Mar;33(2):83-89. 10.5395/JKACD.2008.33.2.083.

Cuspal deflection in class V cavities restored with composite resins

  • 1Department of Conservative Dentistry, School of Dentistry, Seoul National University, Korea. inboglee@snu.ac.kr
  • 2Department of Dental Biomaterials Science, School of Dentistry, Seoul National University, Korea.


The purpose of this study was to evaluate the effect of the polymerization shrinkage and modulus of elasticity of composites on the cusp deflection of class V restoration in premolars. The sixteen extracted upper premolars were divided into 2 groups with similar size. The amounts of cuspal deflection were measured in Class V cavities restored with a flowable composite (Filtek flow) or a universal hybrid composite (Z-250). The bonded interfaces of the sectioned specimens were observed using a scanning electron microscopy (SEM). The polymerization shrinkage and modulus of elasticity of the composites were measured to find out the effect of physical properties of composite resins on the cuspal deflection. The results were as follows. 1. The amounts of cuspal deflection restored with Filtek flow or Z-250 were 2.18 +/- 0.92 microm and 2.95 +/- 1.13 microm, respectively. Filtek flow showed less cuspal deflection but there was no statistically significant difference (p > 0.05). 2. The two specimens in each group showed gap at the inner portion of the cavity. 3. The polymerization shrinkages of Filtek flow and Z-250 were 4.41% and 2.23% respectively, and the flexural modulus of elasticity of cured Filtek flow (7.77 GPa) was much lower than that of Z-250 (17.43 GPa). 4. The cuspal deflection depends not only on the polymerization shrinkage but also on the modulus of elasticity of composites.


Cuspal deflection; Composite resin; Polymerization shrinkage; Modulus of elasticity; Bonded interface
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