Cytotoxicity of provisional restoration materials TEGDMA and urethane dimethacrylate (UDMA).24,25 These resin monomers are able to deplete intracellular glutathione as well as interfere with the expression of some proteins, such as collagen I, osteonectin, and dentin sialoprotein, which play a fundamental role in the pulp repair.26,27 Among the tested materials, Revotek LC is the only UDMA based and light cure provisional material. Geurtsen et al1 reported that UDMA is as cytotoxic as BIS-GMA and TEGDMA. Elution of residual monomers from resin materials related to degree of their polymerization, properties of resin composition, and chemistry of organic solvents in vitro situation.28 Altıntas et al29 demonstrated that leaching of UDMA was lower than BIS-GMA and TEGDMA from a resin cement. Consequently, in present study, eluates of the Revotek LC showed similar cytotoxicity with control group. CoNCLuSIoNS The results of this study demonstrated that cytotoxic potential may vary among provisional materials. Taking into consideration the limitations of this in vitro study, provisional restoration materials may have cytotoxic effects and should be selected carefully for clinical applications. REFERENCES 1. Geurtsen W, Lehmann F, Spahl W, Leyhausen G. Cytotoxicity of 35 dental resin composite monomers/additives in permanent 3T3 and three human primary fibroblast cultures. J Biomed Mater Res 1998;41:474–480. 2. Spahl W, Budzikiewicz H, Geurtsen W. Determination of leachable components from four commercial dental composites by gas and liquid chromatography/mass spectrometry. J Dent 1998;26:137–145. 3. Szep S, Kunkel A, Ronge K, Heidemann D. Cytotoxicity of modern dentin adhesives—in vitro testing on gingival fibroblasts. J Biomed Mater Res 2002;63:53–60. 4. Caughman WF, Caughman GB, Shifflett RA, Rueggeberg F, Schuster GS. Correlation of cytotoxicity, filler loading and curing time of dental composites. Biomaterials 1991;12:737– 740. 5. Ergün G, Mutlu-Sagesen L, Karaoglu T, Dogan A. Cytotoxicity of provisional crown and bridge restoration materials: an in vitro study. J Oral Sci 2001;43:123-128. 118 European Journal of Dentistry 6. Schedle A, Franz A, Rausch-Fan X, Spitler A, Lucas T, Samorapoompichit P, Sperr V, Boltz-Nitulescu G. Cytotoxic effects of dental composites, adhesive subtances,compomers and cements. Dent Mater 1998;14:429-440. 7. Huang F, Chang Y. Cytotoxicity of resin-based restorative materials on human pulp cell cultures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:361-365. 8. Nalçaci A, Oztan MD, Yilmaz S. Cytotoxicity of composite resins polymerized with different curing methods. Int Endod J 2004;37:151-156. 9. Ye RR, Shen QP, Qiao GY. Cytotoxicity of three kinds of temporary crown and bridge materials on mouse fibroblasts in vitro. Shanghai Kou Qiang Yi Xue 2008;17:308- 312 (Abstract). 10. Wassell RW, St George G, Ingledew RP, Steele JG. Crowns and other extra-coronal restorations: provisional restorations. Br Dent J 2002;15:619-630. 11. Tjan AH, Castelnuovo J, Shiotsu G. Marginal fidelity of crowns fabricated from six proprietary provisional materials. J Prosthet Dent 1997;77:482-485. 12. Lang R, Rosentritt M, Leibrock A, Behr M, Handel G. Colour stability of provisional crown and bridge restoration materials. Br Dent J 1998;185:468-471. 13. Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. 3rd Ed. St. Louis: CV Mosby, 2001:380- 416. 14. Yoshii E. Cytotoxic effects of acrylates and methacrylates: Relationships of monomer structures and cytotoxicity. Biomed Mater Res 1997;37:517–524. 15. Sideridou ID, Achilias DS. Elution study of unreacted bis- GMA. TEGDMA, UDMA, and bis-EMA from light-cured dental resins and resin composites using HPLC. J Biomed Mater Res B Appl Biomater 2005;74:617–626. 16. Wataha JC, Craig RG, Hanks CT. Precision of and new methods for testing in vitro alloy toxicity. Dent Mater 1992;8:65-71. 17. Goldberg M. In vitro and in vivo studies on the toxicity of dental resin components: a review. Clin Oral Invest 2008;12:1–8. 18. Saw TY, Cao T, Yap AUJ, Lee Ng MM. Tooth slice organ culture and established cell line culture models for cytotoxicity assessment of dental materials. Toxicol In Vitro 2005;19:145-154. 19. Edmondson JM, Armstrong LS, Martinez AO. A rapid and simple MTT-based spetrophotometric assay for determining drug sensitivity in monolayer cultures. J Tissue Cult Meth 1988;11:15 –17.