Cytotoxicity of two bonding adhesives assessed by three-dimensional cell culture.
OBJECTIVE
To determine the toxicity of orthodontic adhesives assessed on in vitro three-dimensional reconstructed human oral epithelium (RHOE).


METHODS
Two adhesive primers, Transbond XT (3M, Monrovia, Calif) and Excite (Vivadent, Schaan, Liechtenstein), were tested. After topical exposure, the cell cultures were fixed, cut, and stained for light microscopy (LM) and transmission electron microscopy (TEM). Detection of cytotoxicity by measuring lactate dehydrogenase (LDH) activity was performed. Toxicity was assessed by evaluating the morphological changes with LM and TEM. Copper wires and Triton X-100 served as positive controls, and native cell cultures as negative control.


RESULTS
Morphological evaluation of the native cell cultures revealed no toxic reactions. The LDH assay revealed the following mean values for viability: native cell line (negative control), 1.51; Triton X-100 (positive control), 3.06; Transbond XT polymerized, 1.15; Excite polymerized, 1.11; Transbond XT primer, 2.67; and Excite primer, 0.04. Acute toxicity was observed for Triton X-100 and Transbond XT primer (P < .001). Histological evaluation of the RHOE showed toxicity for both primers and mild changes after topical application of polymerized adhesives. The biocompatibility ranking of the adhesive primers was the same after histological analysis and LDH assay except for Excite noncured.


CONCLUSIONS
RHOE proved to be a valuable model for topical exposure. The toxicity of both uncured primers was demonstrated.
Vande Vannet
Bart Maurice Rene Antoine
BM
Department of Orthodontics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium.
Hanssens
Jean Louis
JL
D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003188:Composite Resins / Q000633:toxicity*; D004847:Epithelial Cells / Q000187:drug effects*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008689:Methacrylates / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects*; D019279:Resin Cements / Q000633:toxicity*
D003188:Composite Resins; C420130:Excite cement; D008689:Methacrylates; D019279:Resin Cements; C516047:Transbond XT Light Cure Adhesive Primer; D007770:L-Lactate Dehydrogenase