Purpose: 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) is used to crosslink the collagen contained in dentin. The aim of this preliminary study was to detect the cross-linking reaction promoted by EDC from 10 min to 60 min in two different solutions (absolute EtOH) by measuring the thermal degradation temperature (TDT) of human dentin collagen. The null hypothesis tested was that no differences would have been found among the untreated dentin collagen and the EDC-treated specimens.
Methods and materials: 15 dentin slabs (1 mm thick, 6 mm diameter) were completely demineralized in 10%H3PO4 solution and washed in MilliQ water in agitation for at least 24 h. A Fourier transform infrared (FTIR) spectroscopy analysis of each slab confirmed the absence of mineral. Each demineralized slab was radially sectioned in 6 specimens 1 mm × 1 mm × 1 mm and dried in anhydrous atmosphere with SiO2. 6 specimens of each slab were immersed in the assigned EDC ethanol solution (0.5 M or 1 M) for 10, 20, 30, 40, 50 or 60 min (T10, T20, T30, T40, T50, T60 respectively), rinsed for 15 min in demineralized water under agitation, dehydrated and analyzed with the DSC (DSC, Q10 TA Instruments) to obtain the TDT of EDC-treated collagen. One repetition for each test condition was made. All data were statistically analyzed (Kruskal–Wallis and Mann–Whitney tests).
Results: The thermal degradation temperatures of untreated and EDC-treated dehydrated dentin collagen are shown in the table below (°C, mean). No statistical differences were found.
Conclusion: EDC-treated dentin collagen did not show a higher TDT than the untreated control irrespective of concentration and time of application, thus the test fail to reject the null hypothesis. An improved TDT is an indirect indicator of a more resistant and highly cross-linked collagen network. More data are needed to confirm these preliminary results.
