engleski

Orthodontic adhesives of new formulation – investigation of polymerisation rate and biocompatibility

AIM: The aim of the current research was to test the degree of conversion of orthodontic adhesives of different chemical composition in relation to two curing times and to assess the genotoxicity of such adhesives. MATERIALS AND METHOD: Three adhesives, one primer and three adhesive-primer combinations were tested: bisphenol- A glycidyl dimethacrylate based Transbond XT adhesive and primer (3M Unitek, USA) and two experimental ethoxylated bisphenol-A dimethacrylate based adhesives, one with 40wt.% of amorphous calcium phosphate filler (ACP 40%) and another with 70wt.% of strontium glass filler (Sr 70%). Ten samples of the primer, each adhesive and adhesive-primer combinations were prepared in a simulation of the clinical procedure under a premolar metal bracket and illuminated with the Bluephase Syle curing unit (Ivoclar Vivadent, Liechtenstein) at 1100 mW/cm2 for 10 and 20 seconds, which totaled 140 samples. Fourier transform infrared spectroscopy was used for assessing the degree of conversion (DC) of the samples. The genotoxicity of the adhesives was tested on human gingival fibroblasts (HGF-1 ATCC® CRL- 2014TM, ATCC, USA) with the micronucleus test and comet assay. Analysis of variance and the Student- Neuman-Keuls post-hoc test were used for statistical analysis. RESULTS: After 10 seconds of illumination, Transbond XT and ACP adhesive-primer combinations showed a significantly higher DC (56.6±11.3 and 52.2±9.7) in comparison with Sr 70% adhesive- primer combination (39.1±12.7) and independent adhesives (p<0.05), while the Transbond XT primer showed the highest DC (57.7±2.3). After 20 seconds of illumination, the highest DC was shown by ACP 40% adhesive both independently and combined with the primer (76.9±2.8 and 73.3±2.9, respectively ; p<0.05), while Transbond XT adhesive showed the lowest DC (47.5±3.2). An increase of DC correlated significantly with longer illumination time for all tested materials with the exception of Transbond XT adhesive-primer combination. Genotoxicity was related to lower DC. CONCLUSIONS: After 20 seconds of illumination, bioactive adhesive containing ACP shows a DC that is comparable to that of the Transbond XT. Transbond XT, considered a golden standard, achieves good properties already after shorter illumination time.

orthodontic adhesives ; biocompatibility ; genotoxicity

Rad je dio projekta 13.06.2.1.53 (voditelj Stjepan Špalj) koji financira Sveučilište u Rijeci.