Influence of artificial saliva on abrasive wear and microhardness of dental composites filled with nanoparticles.
OBJECTIVE
The aim of this study is to compare the wear resistance and hardness of two dental nanohybrid composites and to evaluate the influence of artificial saliva storage on those properties.


METHODS
Specimens were made from two commercial nanohybrid dental composites (Esthet-X-Dentsply and Filtek Supreme-3M). Abrasion tests were carried out in a ball-cratering machine (three body abrasion) and microscopic analysis of the wear surfaces was made using optical and scanning electron microscopy; hardness was quantified by Vickers hardness test. Those tests were repeated on specimens stored in artificial saliva.


RESULTS
Results show that the wear rate of the studied materials is within 10(-7)mm(3)/Nmm range, one of the composites presenting wear rate twice as large as the other. After storage in artificial saliva, the wear resistance increases for both materials. Microhardness of the composites is around 52 and 64HV, Esthet-X presents higher hardness values than Filtek Supreme. After storage in artificial saliva, the microhardness of both materials decreases. Data were analyzed using ANOVA test, p < or = 0.05.


CONCLUSIONS
Artificial saliva storage increases the materials' wear resistance, suggesting that in both materials bulk post-cure takes place and saliva absorption occurs only on the surface of the composites. This effect was confirmed by comparing the Vickers hardness before and after artificial saliva treatment and FTIR analyses. Surface microhardness of the composites decreases after storage in artificial saliva whereas bulk microhardness of the materials increases.
Laboratory of Composite Materials, Metallurgical and Materials Engineering Program (PEMM/COPPE), Federal University of Rio de Janeiro, RJ, Brazil. camila@metalmat.ufrj.br
Camila D
CD
Mayworm
Sérgio S
SS
Camargo
Fernando L
FL
Bastian
D003188:Composite Resins; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites; D010316:Particle Size; D012464:Saliva, Artificial; D017550:Spectroscopy, Fourier Transform Infrared
D003188:Composite Resins; C466112:Esthet-X; C474035:Filtek Supreme; D012464:Saliva, Artificial