Objectives . To evaluate the effect of various collagen cross-linking agents on the thermal stability of caries-affected and sound demineralized dentin using a differential scanning calorimetry (DSC) assay.
Materials and methods : Five sound and ten carious human molars were selected. Specimens were cut into 0.2 mm thick slabs from mid-coronal dentin and trimmed to a final dimension of 2.0 × 2.0 × 0.2 mm. To determine caries-affected dentin, sections were stained with a caries detector and sectioned in the same manner described above. Specimens were fully demineralized and randomly divided into 5 experimental groups and a control (no treatment). The cross-linkers used were: 2 synthetic [glutaraldehyde: GD, carbodiimide: EDC] or 3 naturally occuring [grape seed extract: GSE, tannic acid: TA and cocoa extract: COA]. Agents were prepared in distilled water and pH adjusted to 7.2. Samples were treated for 60 min, thoroughly rinsed, sealed in high pressure stainless steel pans, weighted and temperature denaturation ( T d ) was assessed using DSC (Pyrus 1 PerkinElmer) scanned from 25 °C to 130 °C at a rate of 5 °C/min. Cooling and reheating confirmed that the collagen denaturation was irreversible.
Results : The data is depicted in Table [mean (standard deviation)]. There was no significant interaction between factors (substrate vs. treatment, p = 0.990). No statistically significant difference was observed between the T d values of caries-affected and sound dentin ( p = 0.228). The application of collagen cross-linkers resulted in statistically significant increase on T d values ( p = 0.0001). No differences were observed between collagen cross-linkers ( p > 0.05). Multiple peaks up to 106.80°C were observed for GSE, TA and COA dentin treated matrix.
|Dentin matrix temperature denaturation [°C]|
|Dentin substrate||Collagen cross-linking treatment|
|CA||53.11 b (1.13)||80.96 a (3.40)||85.65 a (9.68)||83.60 a (4.87)||77.65 a (6.10)||80.57 a (13.20)|
|Sound||56.20 b (1.92)||81.12 a (1.91)||90.26 a (2.98)||85.62 a (1.60)||79.54 a (8.00)||82.50 a (8.64)|