Synthesis, characterization and swelling kinetics of soft tissue expander hydrogels in dental applications

Hydrogels are cross-linked three-dimensional network structures consisting of hydrophilic homopolymer or copolymers capable of absorbing and desorbing water. They can be synthesized from natural or synthetic polymers or a combination of both in a certain ratio. Natural polymer-based hydrogels are highly biocompatible as they do not show toxic effects on living tissues. Hydrogels swell in water, keeping their shape up to a certain equilibrium volume, depending on their characteristic features. Soft tissue expansion is the use of healthy neighboring tissues in the area applied in the treatment of tissue deficiencies with different techniques and methods. In this study, the swelling behavior and swelling kinetics of chitosan, chitosan-hyaluronic acid, chitosan-gelatin, gelatin-hyaluronic acid and chitosan/hyaluronic acid/gelatin hydrogels planned to be used as soft tissue expanders in dental applications were investigated. Different glutaraldehyde (GA) crosslinker concentrations with 0.4% and 0.6% concentrations were used in the synthesis of chitosan hydrogels. Chitosan-hyaluronic acid hydrogels were synthesized using different crosslinkers (glutaraldehyde and hydroxyapatite). The synthesis in which hydroxyapatite was used as a crosslinker was carried out by gamma radiation synthesis. Swelling behavior and swelling kinetics were investigated by applying dynamic swelling tests in distilled water to the synthesized hydrogels. The swelling behavior of the hydrogels, which are intended to be used as a soft tissue expander, in 5-Fluorouracil anticancer drug was examined and drug absorptions were determined. The characterization of the synthesized hydrogels was done by Fourier Transform Infrared Spectroscopy (FT-IR) and their surface morphologies were examined by Scanning Electron Microscopy (SEM). As a result of the study, the most suitable swelling profile with a mass swelling ratio of 1363% at equilibrium was observed in the chitosan-co-hyaluronic acid (GA) hydrogel synthesized using glutaraldehyde crosslinker. It is predicted that chitosan-co-hyaluronic acid (GA) hydrogel can be used as a soft tissue expander in dental applications due to its hydrophilic structure, due to its highest swelling capacity and drug absorption.