Biophysicochemical Design of a Dual-Function Hydrogel for Synergistic Shock-Absorption and Anti-Inflammatory Action for TMD Therapy

Temporomandibular disorder (TMD) is recognized as a major public health problem, causing pain and physiological and psychosocial limitations. In this context, the present in vitro study investigated the synthesis of a hyaluronic acid (HA) hydrogel with hydrocortisone (Hyd), designed to enhance joint lubrication by reducing mechanical friction and delivering the anti-inflammatory drug. The hydrogels were prepared with 3% HA (30 mg/mL) and Hyd—0.125% (1.25 mg/mL), 0.250% (2.5 mg/mL), 0.500% (5 mg/mL), or 1% (10 mg/mL). Physicochemical analyses included Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), rheological tests (frequency, amplitude, and temperature ramp scans), and field emission scanning electron microscopy (FESEM), performed before and after sterilization and cycling. In addition, cytocompatibility was evaluated by protocol OECD 129 and confocal microscopy, as well as genotoxicity (OECD487) in mouse macrophages (RAW 264.7 strain) per 24 h of exposure. FTIR demonstrated the spectral signatures of the compounds with no covalent interactions between the drugs, as well thermal stability on TGA. Rheology demonstrated that Hyd protected the HA structure after autoclaving, maintaining viscoelastic properties. SEM confirmed homogeneous porous morphology. Biological assays showed cell viability > 70%, but with a dose-dependent increase in genotoxicity (4–17 micronuclei). Confocal analysis revealed increasing cytotoxicity at high Hyd concentrations, indicating a balance between biocompatibility and adverse effects at concentrations ≤ 0.5%. Among the tested formulations, the 3% HA + 0.250% Hyd hydrogel provided the best balance of viscoelastic stability, cytocompatibility, and low genotoxicity, supporting its potential as a dual-function intra-articular candidate for TMD therapy.