title: Cytotoxicity testing of materials with limited in vivo exposure is affected by the duration of cell-material contact.
abstract: Silicones for dental impression largely are used to record the geometry of hard and soft dental tissues. They are considered to be medical devices, and the assessment of cytotoxicity is a necessary step in the evaluation of their biocompatibility. Extracts of six addition-type and six condensation-type silicones have been tested with L929 cells according to the ISO 10993-Part 5 standard. The cytotoxicity was evaluated by three different methods: neutral red uptake, propidium iodide (PI) staining, and amido black staining. According to the selected specific assay, contact between cells and material extracts was maintained for 24 h in the first series of experiments; then, considering that in vivo application of these materials is restricted to a few minutes, additional experiments were performed after 1 h of cell/extract contact. Analysis of the results showed that the addition-type silicones are nontoxic even when tested after prolonged exposure of the cells to the materials while the condensation-type silicones were cytotoxic at 24 h of incubation. Nevertheless, harm to the patient actually could be negligible, considering its very short time of exposure in vivo. This is supported by our finding that most are not toxic after 1 h. We suggest that the experimental conditions of cytotoxicity testing have to be relevant to the in vivo situation; accordingly, the time of exposure should be designed carefully.
authors.affiliation: Laboratory for Biocompatibility Research on Implant Materials, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ciapetti
authors.forename: D
authors.initials: D
authors.lastname: Granchi
authors.forename: S
authors.initials: S
authors.lastname: Stea
authors.forename: L
authors.initials: L
authors.lastname: Savarino
authors.forename: E
authors.initials: E
authors.lastname: Verri
authors.forename: A
authors.initials: A
authors.lastname: Gori
authors.forename: F
authors.initials: F
authors.lastname: Savioli
authors.forename: L
authors.initials: L
authors.lastname: Montanaro
mesh_terms: D000580:Amido Black; D000818:Animals; D001672:Biocompatible Materials / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects*; D004396:Coloring Agents; D003760:Dental Impression Materials / Q000633:toxicity*; D007739:L Cells; D008422:Materials Testing / Q000379:methods; D051379:Mice; D009499:Neutral Red / Q000493:pharmacokinetics; D011419:Propidium; D012828:Silicones / Q000633:toxicity*
chemical_list: D001672:Biocompatible Materials; D004396:Coloring Agents; D003760:Dental Impression Materials; D012828:Silicones; D009499:Neutral Red; D011419:Propidium; D000580:Amido Black