Michał Krasowski

This study evaluated the effect of sports and energy drinks on the surface roughness of three commonly used restorative dental materials: resin-based composites (RBCs), resin-modified glass ionomer cements (RMGICs), and conventional glass ionomer cements (GICs). Sixty-three A2-shade specimens of each material were fabricated, stored in distilled water for 24 h, and then immersed in six commercially available beverages or distilled water (control) for 6, 30, or 60 h. Surface roughness was assessed after each immersion period using contact profilometry, and the effects of material type, immersion medium, and exposure time were compared. Surface roughness increased with longer immersion times for all materials, although the magnitude of change varied significantly among material types. RBCs showed the greatest resistance to surface degradation, whereas RMGICs and particularly GICs exhibited progressively higher roughness values over time. Beverages generally produced greater surface roughness than distilled water, with sugar-containing formulations showing higher roughness values than their sugar-free counterparts. Prolonged exposure to sports and energy drinks may adversely affect the surface integrity of restorative materials. Resin-based composites demonstrated the highest resistance to roughness changes, whereas glass ionomer cements were the most susceptible. Increased surface roughness may contribute to plaque accumulation, staining, and material wear, potentially compromising the long-term clinical performance of restorations.

The use of resin-based composite imitating gum tissue enhances the aesthetics of fillings located below the physiological gum line. The shear bond strength (SBS) between the gum-imitating composite and the traditional composite with different surface preparation methods was examined. The aim of the study was to evaluate which base material—G-aenial Universal Injectable (GC, Japan, flow) or G-aenial A’CHORD (GC, Japan, paste)—performs better, as well as to determine the most effective preparation method among sandpaper (control), 36% orthophosphoric acid (H₃PO₄), sandblasting, and 9.5% hydrofluoric acid (HF). The tested gum-imitating material was Amaris Gingiva (VOCO, Germany). The connection between the composites was evaluated using a Z005 (Zwick-Roell) universal device. Surface tests were carried out using an SJ-410 (Mitutoyo) profilometer. Evaluation of the prepared surface structures was performed using scanning electron microscopy (HITACHI S-4700). Etching with HF significantly improved the shear bond strength between composites. Sandblasting also enhanced the adhesion results, but the H₃PO₄ group achieved comparable results to the control group. However, since HF is not recommended for intraoral use, sandblasting (30 μm aluminum oxide particles applied with three passes at constant speed under a pressure of 2 bar from 1.5 cm) appears to be the most suitable clinical alternative.

Methacrylate-POSS (M-POSS) is a novel organic–inorganic additive shown to reinforce dental composites and reduce polymerization shrinkage. This study aimed to evaluate the influence of M-POSS addition (0.5, 2, 10, or 15 wt.%) on the mechanical properties of an experimental polymer matrix (bis-GMA/UDMA/TEGDMA/HEMA = 35/35/20/10 wt.%) and a dental resin composite (45 wt.% silanized silica as filler). Vickers hardness (HV), three-point bending strength (FS), diametral tensile strength (DTS), and shrinkage stress generated during polymerization were studied. The results show HV values between 16 and 18 compared to 15 ± 1 in the control group. Hardness in the control composite was 34 ± 4, and after modification, it showed similar or slightly lower values between 32 and 35. FS increased from 90 ± 4 MPa before modification to 100 ± 5 MPa for 2 wt.% M-POSS, and then decreased to 78 ± 5 MPa for materials containing 15 wt.% M-POSS. FS of composites were within the range of 61–77 MPa, with a similar tendency in variation to that of matrices. DTS values decreased after M-POSS addition, from 37 ± 4 MPa before modification to 31–33 MPa after modification. Flexural modulus decreases after modification, both for matrices and composites. The morphology of composites with >10 wt. % M-POSS showed visible surface irregularities. In conclusion, M-POSS affects matrix hardness, resulting in an increase in HV. The addition of M-POSS also increases FS values of the matrix, but only up to a certain concentration. However, the introduction of M-POSS does not significantly affect the HV or bending strength of the composites. Although DTS values decreased, this change was not statistically significant. Finally, contraction stress was significantly reduced for groups containing 2 wt.% and 10 wt.% M-POSS, representing an anticipated and promising improvement.

Background: This study aimed to assess the impact of methacrylate-functionalized polyhedral oligomeric silsesquioxanes dispersed in nanosilica (MA/Ns-POSS) on the mechanical properties of light-curable dental resins and composites. The primary goal was to evaluate how different concentrations of MA/Ns-POSS (0.5–20 wt.%) affect the hardness, flexural strength, modulus, diametral tensile strength, polymerization shrinkage stress, and degree of conversion of these materials. Methods: A mixture of Bis-GMA, UDMA, TEGDMA, HEMA, and camphorquinone, with a tertiary amine as the photoinitiator, was used to create resin and composite samples, incorporating 45 wt.% silanized silica for the composites. Hardness (Vickers method, HV), flexural strength (FS), and flexural modulus (E_f) were assessed using three-point bending tests, while diametral tensile strength (DTS) polymerization shrinkage stresses (PSS), and degree of conversion (DC) analysis were analyzed for the composites. Results: The results showed that resins with 10 wt.% MA/Ns-POSS exhibited the highest E_f and FS values. Composite hardness peaked at 20 wt.% MA/Ns-POSS, while DTS increased up to 2.5 wt.% MA/Ns-POSS but declined at higher concentrations. PSS values decreased with increasing MA/Ns-POSS concentration, with the lowest values recorded at 15–20 wt.%. DC analysis also showed substantial improvement for 15–20 wt.% Conclusion: Incorporating MA/Ns-POSS improves the mechanical properties of both resins and composites, with 20 wt.% showing the best results. Further studies are needed to explore the influence of higher additive concentrations.

The use of 3D printing in the fabrication of immediate prosthetic restorations requires the possibility of sterilization. This study aimed to evaluate the effects of different sterilization methods on the parameters of 3D-printing materials for dental prosthesis plates compared to conventional acrylic material. Forty-four samples were prepared for each tested material: Denture 3D+ (NextDent, The Netherlands), Denturetec (Saremco, Switzerland), Optiprint Laviva (Dentona, Germany), and Rapid Simplified (Vertex Dental, Netherlands). The impact strength of the samples was tested in a HIT 5.5P instrument (Zwick Roell, Germany) after three sterilization methods (pressurized steam, ethylene oxide, and radiation) and without sterilization as a control group. Significantly higher energy and impact strength were recorded for the conventional acrylic material. For Nextdent material, the recommended method of sterilization in terms of impaction is autoclave or ethylene oxide sterilization, Saremco—ethylene oxide sterilization, and Denton—ethylene oxide or radiation sterilization. Conventional acrylic material has a higher impact strength than 3D-printed material, which may encourage the selection of this material for restorations requiring higher fracture strength. The possibility of sterilizing the Nextdent 3D-printed material in the autoclave without worsening its durability makes it a recommended choice for digital clinical practice.

Resin-based composites are common and widely used materials in dentistry in direct and indirect applications. Their mechanical properties depend on the composition and homogeneity of the resulting structure. This study aims to optimize the mixing process to obtain the most homogeneous mixture possible, which will allow for the better mechanical properties of the composite. A mixture of bis-GMA/UDMA/HEMA/TEGDMA monomers forming a polymer matrix was filled with silanized silica (45 wt%) using different mixing methods. This study analyzed five manufacturing methods—hand mixing (agate mortar), mixing in a centrifugal Hauschild SpeedMixer, and the hybrid method—combined with the abovementioned methods. The effect of the mixing method on the Vickers hardness (HV), flexural strength (FS), compressive strength (CS), and diametral tensile strength (DTS) of the produced composites was investigated, and the stresses generated during composite polymerization were determined. Mechanically prepared composites have the highest flexural strength and hardness. The lowest shrinkage stress was achieved by the composite, which was prepared partially manually. The results showed that the mixing method affects the morphology of the filler and, hence, the strength properties of the resulting material.

The aim of the study was to compare the hardness, coefficient of friction, and wear experienced by four different ceramic samples: 3Y-TZP zirconium oxide ceramics—Zi—Ceramill Zi (Amman Girrbach), 5Y-PSZ transparent zirconium oxide ceramics—Zol—Ceramill Zolid (Amman Girrbach), Sak—feldspathic ceramics—Sakura Interaction (Elephant), and Glaze (Amman Girrbach). The Vickers hardness of the samples was measured. Friction tests ball-on-disc were performed between the discs of four ceramics and a zirconia ceramic ball, then a premolar tooth as a counter-sample. The mass loss and the friction coefficients of the ceramic samples were determined. The tooth counter-samples were 3D scanned, and enamel attrition depths and mass were measured. The following hardness values (HV1) were obtained: 1454 ± 46 HV1 for Zi, 1439 ± 62 HV1 for Zol, 491 ± 16 HV1 for Sak, 593 ± 16 HV1 for Glaze, and 372 ± 41 HV1 for enamel. The mass losses of the teeth in contact with ceramics were 0.1 mg for Zi, 0.1 mg for Zol, 5.5 mg for Sak, and 4 mg for Glaze. Conventional and transparent zirconium oxide ceramics are four times harder than enamel and three times harder than veneering ceramics. Zirconia ceramics exhibit lower wear and a more homogenous, smoother surface than the other ceramics. Tooth tissues are subject to greater attrition in contact with veneering ceramics than with polished zirconium oxide ceramics.

(1) Background: Mandibular fractures are common, with the condylar process being a frequent site of injury, accounting for 25–45% of cases. This research aims to assess the mechanical suitability of various plates for high-neck condyle fractures. (2) Methods: Polyurethane models mimicking high-neck condyle fractures were utilized in this study. Sixteen distinct plate designs, constructed from titanium sheets, were tested. The figures underwent force assessments on a durability testing apparatus, and the relationship between used force and fracture movement was documented. (3) Results: For high-neck breaking, the two straight plates emerged as the most effective, aligning with established osteosynthesis standards. The second-best plate exhibited nearly half the strength of the gold standard. (4) Conclusions: In response to the aim of this study, considering the mechanical aspects, the double plain plate stands out as the optimal choice for osteosynthesis in cases of high-neck fractures of the mandibular condylar process. In addition, the authors propose the Mechanical Excellence Factor (MEF) as a superior metric for appraising a plate’s mechanical force, surpassing the conventional Plate Design Factor (PDF).

This study aimed to evaluate internal tooth–filling interfaces of composite fillings made using universal adhesives using micro-computed tomography (µCT). Sixty class V cavities were randomly assigned into six groups: Peak Universal etch and rinse (PER), Peak Universal self-etch (PSE), Adhese Universal etch and rinse (AER), and Adhese Universal self-etch (ASE). Two further adhesives considered gold standards were used as control groups: OptiBond FL (OER) for the etch and rinse technique and Clearfil SE for the self-etch technique (CSE). All teeth were subjected to thermomechanical loading and four-year water storage. Next, they were analyzed using µCT to investigate the internal tooth–filling interfaces. The proportions between the gap volume (GV) at the tooth–filling interface and the volume of applied composite filling (FV), between the gap and cavity volumes (CV), and between the gap volumes at the tooth–filling interface of the external (EGV) and internal (IGV) parts were calculated. Adhese Universal achieved the significantly lowest gap-to-filling- and gap-to-cavity-volume ratios for both types of etching techniques comparing to those of the Peak Universal and control groups. Significant differences between the gaps in external and internal parts of the tooth–filling interface were only noted in the control groups. Internal gap formation and development at the tooth–filling interface depend on the material as well as the type of its application.

(1) Background: The mandible is the most frequently injured component of the facial skeleton, with 25–45% of mandibular fractures involving the condylar process. This study aims to mechanically compare which plates are most suitable for use in low-neck fractures of the condyle. (2) Methods: Polyurethane mandibular models with simulated low-neck fractures were tested using 37 distinct plate designs. These plates were fabricated from 1 mm thick, grade 23 titanium sheets. The models were then subjected to force tests on a strength machine, and the correlation between applied force and fracture displacement was recorded. (3) Results: For low-neck fractures, XCP side-dedicated 3+5 and ACP-T plates demonstrated strength comparable to that of two straight plates, the current gold standard in osteosynthesis. (4) Conclusions: The Mechanical Excellence Factor (MEF) introduced by the authors provides a more accurate metric for theoretically predicting a plate’s mechanical strength compared to the Plate Design Factor (PDF). Eight plate characteristics were utilized to calculate the MEF. Employing the MEF allows for rapid, preliminary validation before undertaking strength tests. Furthermore, the findings of this study can guide the selection of the most durable plate designs for subsequent fatigue testing.