The number of studies on the subject of effects of zirconium dioxide (ZrO₂) nanoparticles addition on the mechanical parameters of polymethyl methacrylate (PMMA) is still very limited. Therefore, in this research, the authors wanted to assess PMMA modified with the nano-ZrO₂ additive in terms of changes in flexural, impact and tensile strength values in relation to PMMA without such component. A systematic review and meta-analysis were performed to evaluate the effect of incorporating nano-ZrO₂ into PMMA on individual types of material strength. The obtained numerical data were tabulated and analyzed in the search for percentage changes in those parameters. It was then calculated for each set and the procured model was examined using residual sum of squares (RSS) to assess the discrepancy between the data and the estimation model whilst mean absolute deviation (MAD) was employed to determine robustness. The results of the systematic review were composed of data obtained from individual studies presented in eight independent articles. Overall, the addition of nano-ZrO₂ increases the flexural strength of the composite with the PMMA matrix depending on the size of the ZrO₂ grains administered. Unfortunately, these conclusions are based on a very limited amount of research and require further verification, especially regarding tensile strength.

The treatment of oral and maxillofacial infections is based on a recognized algorithm that may require modification under the influence of various local and systemic factors. The aim of this study was to present a comprehensive and microbiological profile of oral and maxillofacial infections, and explore possible correlations between the course of an infection and selected systemic factors based on the medical records of 329 patients affected by the disease. We identified most common clinical, demographic, bacterial, and laboratory parameters specific for these infections. There were statistically significant differences in Erythrocyte Sedimentation Rate, number of accompanying diseases, otalgia, dyspnea, and speech difficulties occurrence and neck space involvement between diabetic and non-diabetic patients. The duration of hospitalization and accompanying diseases correlated positively with the patient age and white blood cell count, and C-reactive protein value negatively correlated with age. The primary cause of infections, age, and comorbid diseases can modify the infection course and increase the risk of developing serious complications. It confirms the need for effective and targeted bacterial treatment in the early stages of infections. Age and general diseases are the most important systemic factors determining the infection symptoms and laboratory parameters assessing the severity of the inflammatory process.

Polymethyl methacrylate (PMMA), widely used in orthodontics and dentures, exhibits suboptimal mechanical properties, including flexural strength (FS), impact strength (IS), and tensile strength (TS), which are critical for ensuring durability, resistance to fracture, and overall functionality of dental appliances. Silver nanoparticles (AgNPs) are a promising filler due to their antimicrobial properties. This pre-registered (osf.io/yqftx) PRISMA-compliant meta-analysis compared the mechanical properties of PMMA/AgNP composites to pure PMMA, considering mean particle size and concentration. Of 360 records from ACM, BASE, PubMed, and Scopus, 35 studies were included (κ = 0.91), covering 88, 38, and 11 tests on FS, IS, and TS, respectively. FS increased only between 30–70 nm (r = 0.00; ρ = 0.03; R²_deg2 = 0.13). IS remained higher for <80 nm and increased between 15 and 25 nm (r = −0.41; ρ = −0.28; R²_deg2 = 0.59). TS favored 55 nm but had limited data (r = −0.24; ρ = 0.63; R²_deg2 = 0.99). FS decreased with increasing wt%, showing no discernible trend (r = −0.22; ρ = −0.34). IS increased within 0.0–4.0 wt%, particularly 0.5–2.0 wt% (r = −0.15; ρ = −0.35; R²_deg2 = 0.54). TS peaked at 0.5–2.0 wt% (r = −0.20; ρ = −0.24; R²_deg2 = 0.91). Optimal mechanical properties of PMMA/AgNP likely fall within 15–70 nm mean nanoparticle size and 0.5–4.0 wt% concentration.