Cytotoxicity of Universal, Self-Etching and Etch-and-Rinse Adhesive Systems According to the Polymerization Time

Abstract

This in vitro study evaluated in fibroblast cultures the direct cytotoxicity of universal, self-etching and etch-and-rinse adhesive systems according to the polymerization time. Paper discs were impregnated with adhesives and light-cured (10, 20 or 40 s). The discs were then immersed in culture medium to obtain the eluates for the experimental groups (A1-Single Bond 2; A2-Scotchbond Multi-purpose; A3-Clearfil SE Bond; A4 Scotchbond Universal). As a negative control, paper discs were immersed in culture medium only. After 24 h or 7 days, the eluate obtained was applied on fibroblast culture. Cell viability, cell morphology, membrane damage and the presence of residual monomers were evaluated by MTT assay, SEM, flow cytometry and high-performance liquid chromatography (HPLC), respectively. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (=0.05). All adhesive systems significantly reduced 33-51% cell metabolism when compared to the negative control, regardless of polymerization time, storage period and adhesive system. Moreover, the adhesives caused intense morphological alterations and cell membrane damage. Toxicity was directly related to the presence of residual monomers in the eluates. Residual monomers and additional components are capable of reducing mitochondrial activity, causing morphological alterations and disruption of the cell membrane in fibroblasts, regardless of the polymerization time. This study highlights that despite the more complex composition of the universal adhesive system, its biological response was not more toxic when compared with other systems, even when the shortest polymerization time was tested in cell culture.

Cytotoxicity of Self-Etch Versus Etch-and-Rinse Dentin Adhesives: A Screening Study

“…One important finding of our screening study is that Self-Etch and Etch-and-Rinse adhesives showed no statistically significant difference in the observed cytotoxic effects in terms of the qualitative evaluation and the reactivity index. This is in accordance with other studies [14][15][16][17][18][19]. Self-etch dentin adhesives showed more cytotoxicity regarding the quantitative evaluation, which is also in line with previous studies [14,24,[26][27][28].…”

“…Contradictory, other studies found that Etch-and-Rinse adhesives were more cytotoxic [11,17,[20][21][22][23][24][25]. However, in all of the comparative studies, other methods, materials and their combinations were used [11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. It should be noted that in the clinical application of Etch-and-Rinse adhesives conditioning with 37% phosphoric acid is necessary.…”

“…The methods used to evaluate the cytotoxicity are categorized in the assessments of cell damage by morphological means, measurements of cell damage, of cell growth or of specific aspects of cellular metabolism according to ISO 10993-5 [12]. Most studies are based on settings, which are recommended by the ISO 10993-5 under further test procedures to evaluate the cellular metabolism such as MTT or XTT [14][15][16]18,20,21,23,24,[28][29][30][31][32]. An MTT Assay is limited in the distinction of cells that are necrosis or altered into apoptosis [10].…”

“…Dentin adhesive systems with higher cytotoxicity might contain more dimethacrylates of higher toxicity [34], but the dimethacrylates of the test materials are not described any closer from the manufacturers. Additionally, it must be stated that the dentin adhesives systems include other ingredients, e.g., different solvents, which contribute to their cytotoxicity [16,45]. In this study, the materials based on acetone, ethanol and water were tested.…”

Pulp Chamber Heating: An In Vitro Study Evaluating Different Light Sources and Resin Composite Layers

“…The temperature increase was influenced by the light source, and the LED with high irradiance caused higher heating compared to QTH light and low LED, confirming the results obtained in other study (3). This may be due to the fact that the LED emits more specific wavelengths, closer to the absorption spectrum camphorquinone (17), often having a polymerization performance equal to or better than the QTH light (18). However, other authors comparing temperature changes with different photo-activation methods concluded that the QTH light source produced higher temperatures when compared to LED and Plasma Arc light sources (19).…”