Effect of phosphorylated chitosan and carbodiimide on the surface wettability, surface free energy and surface morphology of the eroded dentin.

Abstract

Background: Biomodifiers can reinforce the collagen matrix, improving the biomechanical and biochemical properties of dentin.

Objectives: The present study aimed to evaluate how 2.5% phosphorylated chitosan (P-Chi) and 0.5 mol/L carbodiimide (EDC) affect the surface wettability, surface free energy and surface morphology of the eroded dentin.

Material and methods: Bovine tooth specimens (N = 144) were randomly divided into 6 groups according to the dentin substrate (sound or eroded) and surface treatment (2.5% P-Chi, 0.5 mol/L EDC or no biomodification (control)). Half of the specimens (n = 72) were submitted to erosive challenge by immersion in 0.3% citric acid (pH 3.2) for 2 h. For the surface wettability analysis (n = 12), the contact angles between the dentin surface and the 3M™ Scotchbond™ Universal adhesive were measured with a goniometer. For the surface free energy analysis (n = 3), the contact angles between the dentin surface and 3 organic solvents of distinct polarities (water, formamide and diiodomethane) were recorded. Surface morphology (n = 3) was analyzed with the use of scanning electron microscopy (SEM). The data was statistically analyzed using the two-way analysis of variance (ANOVA) (α = 0.05).

Results: Neither 2.5% P-Chi nor 0.5 mol/L EDC influenced the dentin surface wettability (p > 0.05). Surface free energy decreased in the eroded substrate after biomodification with EDC (p < 0.05). Biomodification with P-Chi demineralized the dentin surface and increased the dentin tubule embouchure.

Conclusions: It can be concluded that 2.5% P-Chi and 0.5 mol/L EDC did not impact the surface wettability of the eroded dentin. However, EDC promoted lower surface free energy, while P-Chi altered surface morphology, causing demineralization and the opening of dentin tubules.