Effects of cavity configuration on composite restoration.
This study evaluated the effects of various cavity configurations on the bond strength, microleakage, flexural strength and elastic modulus of a hybrid (Clearfil AP-X) and a microhybrid (Esthet-X) composite restorative. After the specimens were made with C-factors of less than 1, 2.4 and 3.4, flexural strength and elastic modulus were evaluated in three-point bending using a mechanical testing machine. Fragments of the fractured specimens were selected randomly and the fracture surfaces were examined in SEM. To evaluate the microtensile bond strength and microleakage of composite restorations in bovine cavities, C-factors (ratio of bonded to non-bonded cavity surface) were controlled as 1.0, 2.3, 3.0 and 3.7. All specimens were stored in distilled water at 37 degrees C for 24 hours and tested in a universal testing machine (EZ Test, Shimadzu, Japan). For the microleakage test, teeth with restorations were stained with silver nitrate and examined by two examiners under a stereomicroscope at 40x magnification. The hybrid composite showed higher mechanical properties than the microhybrid composite. The flexural strength and elastic modulus of both composites decreased when polymerized under greater constraint, that is, with increasing C-factor. Mean microtensile bond strength to dentin was also decreased with increasing C-factor for both types of composites. Microleakage scores for the hybrid composite restorations were generally higher than the microhybrid composite.
Choi
Kyoung-Kyu
KK
Department of Conservative Dentistry, School of Dentistry, KyungHee University, Seoul, Korea. choikkyu@khu.ac.kr
Ryu
Gil-Joo
GJ
Choi
Seung-Mo
SM
Lee
Min-Jo
MJ
Park
Sang-Jin
SJ
Ferracane
Jack L
JL
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000528:radiation effects*; D003737:Dental Cavity Preparation; D003763:Dental Leakage; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis; D004548:Elasticity; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D044367:Phase Transition; D018583:Pliability; D018709:Statistics, Nonparametric; D013718:Tensile Strength
C112828:Clearfil AP-X; D003188:Composite Resins; C466112:Esthet-X; D008689:Methacrylates