Influence of light-curing distance on degree of conversion and cytotoxicity of etch-and-rinse and self-etch adhesives

Abstract

BackgroundThe degree of conversion (DC) of resin based materials depends, beside other factors, on the light-intensity applied during light curing. A lower DC might be correlated with an increased cytotoxicity of the respective materials.Therefore, aim of the present study was to investigate the influence of the distance between light-curing tip and adhesives on their cytotoxicity and degree of conversion (DC).MethodsFor the cytotoxicity assay, a total of 98 bovine dentine samples were prepared, distributed to seven groups (G1-G7; n = 14) and treated as follows: G1: untreated; G2-G4: OptiBond FL; G5-G7: OptiBond All-In-One. Adhesives were light-cured (1200 mW/cm2) at 1 mm (G2;G5), 4 mm (G3;G6) or 7 mm (G4;G7) distance. Samples were stored in culture media for 24 h and extracts were added to cell cultures (dental pulp cells and gingival fibroblasts) for a further 24 h. Finally, released lactate dehydrogenase activity (LDH) was photometrically determined, as measure for the cytotoxic effects of the extracts. The cytotoxicity assay was performed three times.Additionally, the DC of the adhesives was determined by FTIR spectroscopy. DC measurements were performed five times.ResultsFor both cell types, no significant difference of LDH release was observed between untreated control group (G1) and treated groups G2-G7 (p > 0.05, respectively), between the groups treated with same adhesive and light-cured at different distance (p > 0.05, respectively), as well as between groups treated with different adhesives and light-cured at the same distance (p > 0.05, respectively). Within the respective adhesive, no significant difference in the DC was observed when light-cured at different distance (p > 0.05, respectively), while OptiBond FL showed significantly higher DCs compared to OptiBond All-In-One when light-cured at same distances (p < 0.05, respectively).ConclusionsThe distance between light-curing tip and adhesive surface does not significantly influence either the cytotoxicity or the DC of the tested adhesives.Electronic supplementary materialThe online version of this article (doi:10.1186/s12903-016-0239-3) contains supplementary material, which is available to authorized users.

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 test of cytotoxicity of these individual bottles is called single applied adhesive part respectively additive analysis sequentially applied adhesive parts. In addition, the evaluation was usually only quantitative [11,15,[18][19][20][21][22][23][24][25][27][28][29][31][32][33][34][35]. A combination of quantitative and qualitative assessments, which is based on ISO 10993-5, is only rarely available in the case of dental adhesives, which refer exclusively to older adhesives like etch-and-rinse ones [3].…”

Cytotoxicity evaluation of eluates from universal adhesives by real-time cell analysis

“…Although there are many researchers studying the cytotoxicity of different generations of dental adhesives 8,16,[62][63][64][65] , studies on the cytotoxicity of universal adhesives are even limited 66,67) . In addition to that, despite the above-mentioned studies, to the authors knowledge, there are no studies that have evaluated the cytotoxicity of universal adhesives using real-time and continuous analysis of cell vitality.…”

The effect of silver nanoparticles incorporation in the self-etch adhesive system on its antibacterial activity and degree of conversion: an in-vitro study

“…Degree of conversion was measured using an Attenuated Total Reflectance/ Fourier Transform Infra-Red spectrometer (ATR/ FTIR) (Vertex 70, Bruker Company, Germany) 4,10 . All the data were recorded and plotted on a special computer software (OPUS Bruker Spectroscopy Software, version 7, Germany) to draw the linear graphs from which the degree of conversion of each specimen was calculated.…”