A laboratory study to assess the physical, mechanical, and 3‐D structural properties of nano‐apatite grafted glass fibre‐based endodontic posts

Abstract

Aim To fabricate and characterize nano‐hydroxyapatite (nHA) grafted and non‐grafted glass fibre‐based endodontic posts. Methodology Experimental glass fibre posts were fabricated using silanized nHA grafted (ex‐HA) and non‐grafted glass fibre (ex‐P) reinforced resins. The structural analysis and morphological patterns were analysed with Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. EverStick® glass fibre posts (eS) were used as a control group. The degree of conversion, flexural strength, and flexural modulus was investigated and the fractured structure was evaluated with a scanning electron microscope. Root canals were prepared in human extracted teeth restored with experimental and control posts. The push‐out bond strength was evaluated with radicular dentine at days 7, 30, and 90, and the presence of voids at the interface were measured at day 1, 7, 30, and 90 with micro‐computed tomography. The Shapiro–Wilk test and one‐way ANOVA post‐hoc Tukey's test were performed. The level of significance was set at 0.05. Results The SEM and FTIR confirmed the presence of a silane‐coupling agent on the glass fibres. The ex‐HA post had a significantly lower degree of conversion compared to the ex‐P post (p = .0008), but a significantly higher conversion than the eS post (p = .0014). The maximum flexural strength value was obtained with the ex‐HA post with an insignificant difference (p = .366) compared to ex‐P post and a significant difference (p = .029) compared to the eS post. The flexural modulus of ex‐HA, ex‐P, and eS posts were significantly different (p = .037). Similarly, the ex‐HA post had a significantly higher push‐out bond strength at days 7 and 30 (p = .037) compared to the ex‐P and eS posts. The volume of voids had a nonlinear behaviour amongst the groups with no significant difference between the posts. Conclusion The fabrication of the experimental posts was successful and the ex‐HA post had greater flexural strength and push‐out bond strength compared to the ex‐P post. The degree of conversion of the ex‐HA post was lower than the ex‐P and eS posts. The volume of voids of ex‐HA and ex‐P posts was lower than that of eS posts.

Effect of thickness on the degree of conversion, monomer elution, depth of cure and cytotoxicity of bulk-fill composites

“…The elution of dental resin composites can be increased by incomplete polymerization, in other words the degree of conversion. It is reported that polymerization of dimethacrylate resins is generally incomplete [16], which is why the degree of conversion remains within the range 55-75% for bulk-fill resins. However, although for adequate clinical performance, a conversion rate has not yet been stated, a minimum of 55% is recommended, at least for occlusal restorative layers [7].…”

Preparation of Nano-Apatite Grafted Glass-Fiber-Reinforced Composites for Orthodontic Application: Mechanical and In Vitro Biofilm Analysis

“…Later, the filtrate was dried at 60 °C for 72 h. Then, the samples of both batches were stored in a desiccator to avoid moisture contamination. The structural and morphological patterns of silanized fibers were analyzed by Fourier transform infrared spectroscopy (FTIR; Thermo Fisher Scientific, Waltham, MA, USA) and scanning electron microscopy (SEM; Tescan Vega 3, Brno-Kohoutovice, Czech Republic), as described (images provided in Supplementary Materials , Figure S1 ) in detail previously [ 28 ].…”