This study aimed to evaluate the effect of various surface treatments of a fiber post on the bond strength to a composite core. The polished flat surfaces of fiber posts received different treatments: C (no surface treatment), S (silanization only), HS (30% hydrogen peroxide etching followed by silanization), HNS (etching with a 30% hydrogen peroxide/5 wt% sodium bicarbonate mixture followed by silanization), and SBS (sandblasting and then silanization). Resin composite cylinders were bonded on each pretreated surface and all bonded samples were stored in water at 37ºC for 24 h, with half of them additionally thermocycled for 10,000 cycles before microshear testing. Surface morphology and elemental composition of the conditioned post surfaces were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. The HNS exhibited the highest bond strength, regardless of thermocycling (p<0.05). Although etching and sandblasting increased surface roughness, sandblasting caused structural damage of the post.

Calcium phosphate (CaP) bioceramics, including apatite (Ap)-based materials, are naturally biocompatible, but they frequently require surface functionalization to achieve optimal integration with biological systems, especially with immune cells. Surface functionalization strategies tailor CaP bioceramic nanoparticles to enhance cell adhesion, proliferation, differentiation, and overall biocompatibility. This is because functionalized surfaces interact more dynamically with immune cells, i.e., macrophages, dendritic cells, and lymphocytes, through surface receptors and signaling pathways. The dynamic interaction may activate immune cells, release cytokine, differentiate cells, and regulate inflammation. Therefore, to resolve the limitations of natural CaP bioceramics, surface functionalization is crucial. Modified bioceramics nanoparticles’ surface properties ensure more effective integration with biological tissues. In addition, biomolecule immobilization on CaP bioceramic surfaces provides a versatile approach in establishing a foundation for the development of immunomodulatory biomaterials. This review provides an overview of recent biomedical research on CaP bioceramics, especially Ap-based materials, focusing on advancements in surface functionalization strategies designed to improve interactions with immune cells. It also examines the role of immobilized biomolecules in modulating immune responses, highlighting their potential for clinical applications.

Polyetheretherketone (PEEK) cannot be used without veneering in the anterior area. This study aims to observe the influence of the various surface treatment protocols on the shear bond strength (SBS) between veneering resin composite and PEEK. Sixty cylindrical PEEK specimens (16×5 mm) were fabricated using CAD-CAM, and divided into six groups (n=10) based on the surface treatment method: NT: no treatment (control), SA: 98% sulphuric acid, HP: 30% hydrogen peroxide, SB: airborne particle abrasion with 50 µ aluminum oxide particles, SL: silicatization followed by silanization, and HF: 9.5% hydrofluoric acid. After the application of the resin composite, specimens were thermocycled and subjected to fracture testing using a universal testing machine. Fractured surfaces were examined microscopically and the data were analyzed statistically. The SA and SL groups exhibited significantly higher mean SBS values (p<0.001), although the difference between them was not statistically significant (p=0.24).

This study aimed to evaluate the conditions for the finish line position and gingival retraction width that allow for taking optical impressions using three-dimensional (3D) printed models. Taking an impression using an intraoral scanner (IOS) is widely performed in fabricating crown prostheses. Measuring the subgingival finish line using an IOS is difficult; to obtain optical impressions of the subgingival finish line, the gingival retraction has been recommended. However, no study has evaluated the amount of gingival retraction width and the depth of the finish line. In this study, the measurement limits of the subgingival finish line using an IOS and models fabricated by a 3D printer were investigated. The results of this study revealed that TRIOS3 could not measure the finish line when the gingival retraction width was <0.25 mm, and the finish line was located >0.50 mm below the gingival margin.

The objective of this study was to evaluate polyetheretherketone (PEEK) as a post material for resin core abutments in bovine root by static and dynamic fracture loads, with comparison for fiber-reinforced composite (FRC) post. Resin core abutments using experimental PEEK post (CR-PEEK) and bovine root (BRA-PEEK) were fabricated. Specimens including those built-up FRC posts instead of PEEK posts (CR-FRC and BRA-FRC) were also evaluated for load durability under static and dynamic loading tests. CR-PEEK had a lower fracture load than CR-FRC. BRA-PEEK and BRA-FRC had similar static and dynamic loads, with the primary fracture mode involving delamination of the abutment from the tooth structure due to ferrule fracture, with plastic deformation in the experimental PEEK post. In conclusion, experimental PEEK post could be a viable post material for resin core abutment when used in combination with resin composite.

This study investigated the impact of 1,500 ppm fluoride-containing toothpaste on the surface properties of CAD-CAM resin composites. An accelerated degradation test was performed using five commercial NaF-containing toothpastes, which were applied to two commercial CAD-CAM resin composites and stored under static conditions at 37°C for 14 days without mechanical brushing. The results showed that four toothpastes significantly increased surface roughness and reduced gloss. To further elucidate this phenomenon, a similar accelerated degradation test was conducted using experimental aqueous solutions containing NaF (1,500 ppm) and sodium dodecyl sulfate (SDS; 2 wt%), a common component in the toothpastes that caused the most severe degradation. The findings indicated that SDS accelerates the degradation of CAD-CAM resin composites in the presence of NaF, suggesting that toothpastes containing both NaF and SDS contribute to the deterioration of surface properties.