Impact of Dentin Substrate Modification with Chitosan-Hydroxyapatite Precursor Nanocomplexes on Sealer Penetration and Tensile Strength

Abstract

Introduction: The purpose of this study was to evaluate the effect of dentin conditioning with chitosan-hydroxyapatite precursor (C-HA) nanocomplexes on the depth of tricalcium silicate sealer penetration into dentinal tubules and ultimate tensile strength (UTS).

Methods: surface charge and size distribution for C-HA nanocomplex formulation was evaluated followed by bioactivity assessment of standardized films of C-HA nanocomplexes (n = 15) incubated in simulated body fluid. Mineralization potential was assessed with X-ray diffraction and Fourier-transform infrared spectroscopy, whereas scanning electron microscopy was used for ultrastructural evaluation. Static water contact angles and UTS were measured on dentin discs (n = 2/group) and dentin beams (n = 10/group) treated with/without sodium hypochlorite/EDTA and C-HA nanocomplex conditioning. In phase 2, the depth of sealer penetration after C-HA nanocomplex conditioning was evaluated using fluorescent imaging (n = 12/group). The percent area penetration and mean/maximum penetration depth were calculated at 4- and 6-mm levels from the root apex. Data from contact angle measurements, mechanical testing, and penetration assessment parameters were subjected to the independent samples t test with a significance level set at P < .05.

Results: A formulation of C-HA nanocomplexes (2 mg/mL) was chosen as a polyanionic, hydrophilic, nonaggregating concentration having bioactivity potential established through the formation of phosphate/carbonate bonds and the crystalline nature of the formed minerals. A significantly lower contact angle and higher UTS were registered for the C-HA nanocomplex-conditioned group (P < .05). Statistically significant (P < .05) greater sealer penetration was recorded at the 4-mm level for all assessment parameters and percent area penetration at 6 mm for the C-HA nanocomplex group.

Conclusions: C-HA nanocomplex conditioning enhances dentin surface wettability to facilitate greater tricalcium silicate sealer penetration and UTS of dentin.

Keywords: Chitosan; Sealer penetration depth; dentin; nanocomplexes; ultimate tensile strength.