The study investigated the impact of aging on surface roughness, color stability, and biocompatibility of hybrid resin-ceramic materials. A total of 225 specimens were produced from three three-dimensional (3D)-printed (HarzLabs Dental Sand Pro (HL), BEGO VarseoSmile Crown plus (BV), Voco V-Print c&b temp (VV)) and one milled material (Voco Grandio Blocs (VG)). Specimens were grouped into untreated, polished, and glazed surfaces. 5000 thermal cycles simulated aging. Surface roughness and color stability were analyzed, and surface topography was observed using scanning electron microscopy (SEM). Biocompatibility was evaluated with L929 cells. Surface roughness differed significantly between untreated and other groups, with no changes before and after artificial aging. Untreated milled samples were significantly smoother than 3D-printed ones. SEM analysis revealed roughest surfaces in untreated 3D-printed specimens. Polished and glazed specimens were smoother than untreated ones. Color values showed significant differences between untreated and treated/aged groups. No material showed cytotoxicity. In summary, untreated VG was smoother than 3D-printed materials, but polishing and glazing reduced roughness to levels comparable to VG. Surface treatments induced color changes, with glazing causing more changes than polishing. Aging affected color stability and biocompatibility but not surface roughness. All materials showed acceptable color changes and good biocompatibility.

The aim of this study was to compare the potential of standard ion-releasing materials to repair demineralized lesions with recently introduced alkasite and glass hybrid materials. Glass ionomer (GC Fuji TRIAGE), two glass hybrids (EQUIA Forte HT, Riva SC), calcium silicate cement (Biodentine) and an alkasite (Cention Forte) were tested. A total of 72 human third molars were used for sample preparation; on the dentine surface, a class-I cavity was prepared, and one half was covered with nail varnish. The teeth were subjected to a demineralization protocol, filled with the examined materials, and cut in half. The evaluation included a dentine microhardness assessment (n = 10) and SEM/EDS analysis (n = 2). The results were analyzed using SPSS 22.0 statistical software and compared using an analysis of variance and Scheffe post-hoc test. The statistical significance level was set to 0.05. Mean microhardness values (HV0.1) after 14 and 28 days were, respectively: EQUIA Forte HT (26.7 ± 1.45 and 37.74 ± 1.56), Riva Self Cure (19.66 ± 1.02 and 29.58 ± 1.18), Cention Forte (19.01 ± 1.24 and 27.93 ± 1.33), Biodentine (23.35 ± 1.23 and 29.92 ± 1.02), GC Fuji TRIAGE (25.94 ± 1.35 and 33.87 ± 5.57) and control group (15.57 ± 0.68 and 15.64 ± 0.82). The results were significantly different between most groups (p < 0.001). SEM/EDS revealed varying patterns, material deposits and distinct elemental variations. To conclude, all materials increased microhardness and affected the dentine surface appearance and chemical composition; EQUIA Forte HT demonstrated the most pronounced effects.

The rapid advancement of three-dimensional (3D) printing in dentistry has prompted comparisons between the mechanical properties of polylactic acid (PLA) samples fabricated using material extrusion (MEx) and resin samples produced using digital light processing (DLP). This study aims to assess the potential of replacing resin-based models with PLA models in clinical settings by evaluating the mechanical properties and accuracy of MEx-printed PLA and DLP-printed resin samples. The investigated materials include pure PLA, a PLA composite containing gypsum, and a clinically approved resin material. Strength and hardness tests were conducted using custom-made samples measuring 16 × 4 × 2 mm ³ . Additionally, oral cavity scans were used to generate oral models for each material to assess their accuracy, trueness, and precision. The results indicated that pure PLA exhibited the highest flexural modulus (2055 ± 217.70 MPa) and compression modulus (2.40 ± 0.14 GPa). The PLA-Gypsum composite displayed the highest hardness (19.48 ± 2.12 HV1). As for the trueness of the oral models, there were no statistically significant differences between the models made from the three materials. However, the PLA-Gypsum composite demonstrated the best precision (23.84 ± 4.12 μm). These findings suggest that both PLA materials have significant potential to replace DLP-produced resin models in the clinical applications. Graphical Abstract

3D printing is increasingly utilized in dentistry. Compared to traditional manufacturing methods, 3D printing provides advantages such as faster production times and the ability to create complex structures. Although biocompatible materials are available, many are only suitable for temporary applications. This study examines the impact of nitrogen-aided post-processing on the mechanical properties and cytotoxicity of 3D-printed denture bases, with the hypothesis that this post-processing will enhance material properties and decrease cytotoxicity. Specimens were fabricated from V-print dentbase (Voco GmbH, Cuxhaven, Germany) and post-processed either in nitrogen or air. The specimens were categorized into aged and non-aged groups. For comparison, specimens made from milled material were utilized. Vickers hardness, flexural strength, polishability, cytotoxicity, and degree of conversion were then assessed for all groups. The data were analyzed using a one-way ANOVA and Tukey HSD test for multiple comparisons, with a significance threshold of p < 0.05. Post-curing with nitrogen improved the degree of conversion, surface hardness, and biocompatibility of 3D-printed dental materials, confirming reduced cytotoxicity without impairing mechanical properties. Nitrogen increased polymerization and decreased harmful monomers, making it ideal for clinical applications in contact with the oral mucosa. Optimizing post-processing steps, such as curing in nitrogen, enhances biocompatibility while maintaining strength and hardness, ensuring better patient care in dental applications.

(1) Purpose: To compare the fabrication accuracy, internal fit, and marginal adaptation of three-unit definitive resin fixed dental prostheses (FDPs) produced by subtractive milling and additive manufacturing. (2) Materials and Methods: A typodont mandible was prepared for a three-unit FDP, with full crown preparations on teeth mandibular left canine and mandibular left second premolar featuring 1 mm chamfer finish lines. The FDP was designed with a 16 mm² connector and a 100 µm cement gap. Two milling materials (Ambarino High-Class, IPS e.max CAD) and two experimental 3D printing hybrid resins (3D-1, 3D-2) were used. All restorations were scanned using an intraoral scanner and compared to the original STL using reverse engineering software for surface trueness and deviation analysis. The internal fit was evaluated using the triple-scan method, while marginal fit was assessed via micro-CT imaging. Statistical analysis was conducted using one-way ANOVA and Kruskal–Wallis tests (α = 0.05). (3) Results: Milled groups demonstrated a lower prevalence of external, marginal, and overall surface deviations (p < 0.001), while 3D-1 exhibited comparable deviations within the internal region with M-E (p = 0.067). Milled groups had average gap values that were similar to 3D-1 (p > 0.08), but significantly lower than 3D-2 (p < 0.002). In marginal adaptation evaluated by micro-CT, the M-A and M-E groups provided significantly lower gaps, while the 3D-1 and 3D-2 groups exhibited wider marginal and axial gaps. (4) Conclusions: These results indicate that while milling remains a more reliable manufacturing method for achieving external and marginal precision, position 3D-1 is a compelling, chairside alternative to milling.

Background/aim: This in vitro study aimed to evaluate and compare the retentive forces of novel nonmagnetic abutment designs developed as an alternative to conventional magnetic abutments for facial prostheses.Materials and methods: A plexiglass model was constructed and two extraoral implants were placed in these blocks in a parallel position. Nonmagnetic abutments made of titanium were fabricated and screwed onto the implants. The nonmagnetic systems represent a novel design and include two different abutment designs (Type 1 and Type 2) with silicone attachments. Retentive force values for three abutment types: Conventional Magnetic System (CMS), Nonmagnetic abutment Type 1 System (NMS1), and Nonmagnetic abutment Type 2 System (NMS2) were measured at 0th, 120th, 360th, 720th, and 1440th dislodging cycles using a test machine. Given the data's distribution characteristics, non-parametric tests were used for analysis. The Kruskal-Wallis test evaluated significant differences among groups, followed by Dunn's post-hoc test for specific group comparisons. The Friedman test compared the number of dislodging cycles for each group, and the Benjamini-Hochberg adjusted Wilcoxon sign-rank test was used for pairwise comparisons.Results: Both NMS1 and NMS2 groups exhibited significantly higher retentive forces compared to CMS for each of the same dislodging cycles (p<0.01). The NMS1 group showed the highest initial retentive force (9.98±0.89 N), followed by the NMS2 group (9.65±0.35 N), but this difference was not statistically significant. Significant differences in retention force values were observed among the three groups across the dislodging cycles (p<0.001). The lowest retentive force in the last dislodging cycle was observed in the CMS group (3.39±0.04 N). Additionally, the retention forces decreased in all groups with each increasing dislodging cycle.Conclusion: The two newly developed nonmagnetic systems displayed higher retentive forces compared to the magnetic systems and can be considered a viable alternative abutment option for facial prostheses.