title: The Influence of Zinc Oxide Eugenol (ZOE) and Glass Ionomer (GI) Base Materials on the Microhardness of Various Composite and GI Restorative Materials.
abstract: OBJECTIVE
  Re-examining the well accepted concept that Zinc-Oxide-Eugenol bases (ZOE) have a negative effect on composite restoration materials microhardness, in light of the advancement in composite materials and newer publications.
  
  
  METHODS
  Five modern composite restoration materials were used, including hybrid (Xtra-fill and Z250), micro-fill hybrid (G-aenial and Gradia-direct) and methacrylate-free restorative material (Silorane- oxirane). Two base materials were used IRM (ZOE-base) and Fuji-IX (GI-base). Samples were made using a designed mold, in which composite discs were cured on top and in close relation to base materials. Micro-hardness testing was performed using a DMH-2 microhardness tester utilizing the Knoop method.
  
  
  RESULTS
  Statistic analysis demonstrated significantly better microhardness of three composite materials when IRM was used as base in comparison to control (G-aenial, Gradia direct and Filtek silorane), and no differences in two materials (Filtek universal Z250 and Voco Xtra-fil). Fuji-IX bases showed a significant positive effect on the microhardness of four composite materials, and a negative effect on one material (Voco Xtra-fill). In comparison with other tested restoration materials, both Voco Xtra-fill and Fuji-IX showed higher microhardness results (P<0.05).
  
  
  CONCLUSIONS
  Related to microhardness, both ZOE and GI bases can be used safely as bases under composite restorations. The results of this study together with the results published recently showed that the concept of not using ZOE or GI bases under composite must be reconsidered. Fuji IX showed microhardness results similar to the best composite material and therefore it can be used as a restorative material.
authors.affiliation: Faculty of Dental Medicine, Hebrew University, Hadassah, Ein Karem, Jerusalem, Israel.
authors.forename: Roee
authors.initials: R
authors.lastname: Itskovich
authors.affiliation: Department of Oral Rehabilitation, Gabriela Goldshlager School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Israel
authors.initials: I
authors.lastname: Lewinstein
authors.affiliation: Faculty of Dental Medicine, Hebrew University, Hadassah, Ein Karem, Jerusalem, Israel ; Pediatric Dental Department, Barzilai Medical Center, Ashkelon, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Zilberman
keywords: Composite; Fuji-IX; Glass-ionomer; IRM.; Knoop method; Microhardness; Zinc oxide eugenol