Toward Enhanced Bone Regeneration: Investigating the Impact of Wollastonite Phases and Buffered Solutions in Calcium Silicate Cements

Abstract

As life expectancy rises, the demand for effective bone regeneration materials becomes imperative, particularly in addressing age-related conditions such as osteoporosis, arthritis, and dental surgeries. This study focuses on the urgent development of materials aimed at filling the implant-bone interface and enhancing bone regeneration. Wollastonite (CaSiO₃), a calcium silicate ceramic, stands out for its superior biocompatibility and hydroxyapatite-forming capability compared to phosphate-based cements. The primary objective of this research is to assess the influence of different wollastonite phases and buffered solutions on the production of calcium silicate cements. Four types of cement were evaluated, varying the studied phase (α and β-wollastonite) and the activating solution ((NH₄)₂HPO₄ and K₂HPO₄). Characterization techniques such as X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM) were employed to elucidate the impact of each phase and ion on material properties. Compressive strength analysis and biological tests were also conducted. The physicochemical analysis revealed that the α-wollastonite phase exhibits more non-bridge oxygen (NBO) bonds and silanol groups than β-wollastonite, suggesting superior bioactivity. XRD, FT-IR, and Raman results demonstrated that cements prepared with ammonium buffer solutions formed hydroxyapatite, enhancing compatibility with bone tissue. Compressive strength tests showed overall equivalent strengths (approximately 6 MPa), except for the sample prepared with β-wollastonite and potassium phosphate, which exhibited lower resistance to compression. Alkaline phosphatase data indicated that cements formed with α-wollastonite phase and (NH₄)2HPO₄ presented superior potential for bone regeneration.