Nicole Grüßner

Background: With an increasing demand for aesthetic treatments, tooth bleaching is becoming a common procedure. Thus, a range of bleaching products are nowadays available at the market. As it is important to consider adverse effects on surrounding soft tissue, the paper aims at evaluating possible cytotoxic effects on fibroblasts in vitro. Respectively, commonly used gingiva barriers should also be critically examined regarding biocompability. Methods: Seven At-Home bleaching products (Opalescence 10/ 15/ 20, Perfect Bleach 10, Perfect Bleach 16, Viva Style 16 and White Strips), two In-Office products (Easy White Ready Kit and Opalescence Quick) and two gingiva barrier products (Easydam and Opaldam) were used for cytotoxic evaluation on primary human fibroblasts after 48h. Quantitative evaluation was performed using a cell counter for cell viability and qualitative evaluation was performed using cytotoxic grading based on morphological assessment according to ISO 10993-5. Results: There were no significant differences regarding viable cells between At-Home and In-Office bleaching products nor between gingiva barriers and the cell control. All In-Office bleaching products and three At-Home products (Opalescence 15 and 20 and Perfect Bleach 16) showed significant fewer viable cells than the cell control. Based on the qualitative assessment, the same bleaching products, except for Perfect Bleach 16, could be categorized as cytotoxic according to ISO 10993-5. Conclusions: Cytotoxic effects could be observed within At-Home and In-Office bleaching products by qualitative and/or quantitative means. Gingiva barriers showed no cytotoxic effects and their use as part of bleaching treatments seems to be beneficial for protecting the surrounding soft tissue.

Objectives: Six dentin adhesives were tested in vitro regarding their cytotoxicity toward human fibroblasts. AdheSE, Clearfil SE Bond, Hybrid Bond, One-up Bond F Plus, Optibond Solo Plus, and Syntac were tested using a cell culture model. The several components of dentin adhesives, like the primer and bonding, were analyzed as single and additive applied components as specified by the manufacturer for application in vivo. Methods: Seventy-five Petri dishes were produced per adhesive and control group, and all 525 Petri dishes were evaluated using multiparametric strategies, i.e., using multiple methods to strengthen the reliability of the results. The multiparametric strategies consisted of automated cell counting for viability, microscopic morphological assessment and lastly of reactivity grading according to ISO 10993-5. These assessments were performed after our initial investigation, and the observation period was extended from 24 h to 48 h. Results: AdheSE, Clearfil SE Bond, One-up Bond F Plus, and Optibond Solo Plus showed statistically significant reductions in viable cells relative to the cell control. All dentin adhesives except Clearfil SE Bond showed a statistically significant difference regarding the reactivity index in the application comparison. Conclusions: The test materials showed a moderate degree of cytotoxicity, with no statistically significant difference between the tested self-etch and etch-and-rinse dentin adhesives. However, the results show statistically significant differences between the adhesives when applied sequentially and once. Further research addressing mechanisms of cytotoxicity is needed for advancement in this field.

Six dentin adhesives were tested in vitro regarding their cytotoxicity on human fibroblasts. Hybrid Bond, One-up Bond F Plus, AdheSE, Clearfil SE Bond, Optibond Solo Plus and Syntac were tested by using a cell culture model. The several components of dentin adhesives like primer and bonding were analyzed as single and additive applied components as specified by the manufacturer for the application in-vivo. 75 petri dishes were produced per group and all petri dishes (480 ones) were evaluated triangulated. This unique assessment is following our first investigation and the observation period is extended from 24 hours to 48 hours. AdheSE, Clearfil SE Bond, One-up Bond F Plus and Optibond Solo Plus showed statistically significant less amounts of viable cells compared to the cell control. All dentin adhesives except Clearfil SE Bond showed a statistically significant difference regarding the reactivity index in the application comparison. In conclusion, the test materials showed a moderate grade of cytotoxicity with no statistically significant difference regarding the cytotoxicity between the tested self-etch and etch-and-rinse dentin adhesives. However, the results show differences between sequentially and single applied adhesive parts.