Effect of Different Concentrations of Nano-Hydroxyapatite on the Microshear Bond Strength of Zirconia to Resin Cement Publisher Pubmed

Summary: Curious about dental material strength? Research suggests a thin layer of nano-hydroxyapatite enhances bond strength of zirconia to resin cements. Is this the future of dental restorations? #DentalResearch #MaterialsScience

Nikzad S ; Zare A ; Atri F ; Jafarpour D ; Zare S ; Azari A
Source: International Journal of Prosthodontics Published:2026

Abstract

Purpose: To assess the impact of nano-hydroxyapatite (n-HA) coating of different concentrations on the microshear bond strength (µSBS) of zirconia ceramics to resin cements. Materials and Methods: A total of 48 Cercon Y-TZP blocks (4 × 4 × 4 mm) were randomly divided into four groups (n = 12): (1) control group, (2) 5-g n-HA coating, (3) 10-g n-HA coating, and (4) 15-g n-HA coating. The specimens were sintered at 1,250°C. The thickness of the coatings was characterized using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses were carried out to characterize the surface. All specimens were then bonded to Panavia F2.0 cement. Microshear bond testing was carried out using a universal testing machine. Stereomicroscope imaging was used to evaluate the zirconia surface failure mode. The data were analyzed using Kruskal-Wallis and Mann-Whitney tests, and P < .05 was considered statistically significant. Results: The mean µSBS value of the 5-g n-HA–coated group with a thickness of 7.71 ± 2.51 µm was 28.30 ± 3.02 MPa, which was significantly higher than the control group with the mean value of 19.94 ± 1.86 MPa (P < .05). The mean µSBS value of the 10-g and 15-g n-HA groups with thicker coatings were 21.66 ± 3.63 MPa and 15.23 ± 3.34 MPa, respectively. Additionally, the main mode of failure for the 5-g n-HA group was a mixed failure. In contrast, the adhesive mode of failure was more dominant in the control group. EDS and XRD analysis revealed the formation of crystalline HA on zirconia blocks, highlighting the predominant zirconia peak at 32 degrees. The SEM analysis of the coated specimens displayed a uniform layer of n-HA coating with evident cracks filled with the resin cement. These cracks themselves can help increase the bond strength between ceramic and resin cement. Conclusions: A thin coating of nanocrystalline hydroxyapatite on zirconia surfaces can be effective in enhancing the microshear bond strength of these ceramics to resin cements. The microshear bond strength of n-HA–coated zirconia was significantly higher compared to the untreated specimens. ©2026 by Quintessence Publishing Co Inc.