title: Comparison of different test models for the assessment of cytotoxicity of composite resins.
abstract: This study compared the use of different test models to assess the cytotoxicity of a dental composite. The cytotoxicity of a composite polymerized using two halogen-based light-curing units (LCUs) (Max LC and Astralis) and two light-emitting diode LCUs (E-light and Freelight) served as the basis of comparison. Disk-shaped specimens (7 mm diameter, 2 mm high) were fabricated using the four different light sources. The specimens were used in several cytotoxicity test models: direct and indirect contact tests as well as an extract test with an established cell line L-929. The cells were stained with neutral red after cell-material contact for 48 h. Neutral red-stained areas (in mm2, for direct and indirect tests) and absorbance readings (for extract tests) were analysed statistically using ANOVA and the Tukey post hoc test, with P < 0.05 considered to be significantly different. Good correlation between direct and indirect contact tests (r = 0.903) was found. The extract test was the least correlated among the three tests. It was found that the E-light + Freelight-cured composite elicited cytotoxicity from the correlated studies. Uncured specimens were most detrimental to the cells in all tests. Our data demonstrated that composite cured with light-emitting diode LCUs were cytotoxic to L-929 cells. Different test models were found to give rise to different findings. Thus, a good cell-material contact method would replicate more closely the physiological situation in vivo. This in turn would give more clinically relevant results.
authors.affiliation: Cell and Tissue Culture Laboratory, Faculty of Dentistry, National University of Singapore, 5 Lower Kent Ridge Road, 119074 Singapore. dencaot@nus.edu.sg
authors.forename: Tong
authors.initials: T
authors.lastname: Cao
authors.forename: Tzuen Yih
authors.initials: TY
authors.lastname: Saw
authors.forename: Boon Chin
authors.initials: BC
authors.lastname: Heng
authors.forename: Hua
authors.initials: H
authors.lastname: Liu
authors.forename: Adrian U Jin
authors.initials: AU
authors.lastname: Yap
authors.forename: Mah Lee
authors.initials: ML
authors.lastname: Ng
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods*; D003188:Composite Resins / Q000737:chemistry / Q000633:toxicity*; D003764:Dental Materials / Q000737:chemistry / Q000633:toxicity*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006219:Halogens; D007739:L Cells; D008029:Lighting / Q000295:instrumentation; D051379:Mice; D012680:Sensitivity and Specificity; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D006219:Halogens