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.

Introduction: Hyaluronic acid, steroids and blood products are popularly injected into the temporomandibular joint (TMJs) to relieve pain and increase the extent of mandibular abduction. The purpose of this review is to identify other injectable substances and to evaluate them in the above-mentioned domains. Material and methods: The review included articles describing clinical trials of patients treated with intra-articular injections with or without arthrocentesis. Results: The following emerging substances were initially evaluated to be effective in treating TMJ pain and increasing the amplitude of mandibular abduction: analgesics, dextrose with lidocaine, adipose tissue, nucleated bone marrow cells and ozone gas. Discussion: Better effects of intra-articular administration are achieved by preceding the injection with arthrocentesis. Conclusions: The most promising substances appear to be bone marrow and adipose tissue.

Objectives: The purpose of this systematic review with meta-analysis is to identify clinical studies concerning the impact of intra-articular administration of hyaluronic acid (HA) on mandibular mobility and to make an attempt at determining the efficacy of HA in this indication. Methods: The review included primary studies involving groups of at least 10 patients who were diagnosed with pain in the temporomandibular joint and who were injected with hyaluronic acid as the only intervention. The outcomes pursued were changes in mandibular mobility and pain intensity. Four databases of medical articles were searched, including PubMed and BASE. The risk of bias was assessed using the Cochrane methodology tools. The therapy‘s efficacy was calculated in the domains of mandibular abduction, protrusive movement, lateral mobility, and pain relief. For these values, the regression and correlation with variables characterizing the interventions were analyzed. Results: In total, 16 reports on 20 study groups with a total of 1007 patients qualified for the review. The mean effectiveness in the domain of mandibular abduction over the 6-month follow-up period was 122% of the initial value, and the linear regression model can be expressed as 0.5x + 36. The level of pain in the same time frame decreased to an average of 29%. The severity of pain 6 months after the beginning of treatment positively correlates with the number of injections per joint (0.63), the total amount of drug administered in milliliters (0.62), and the volume of drug administered monthly per joint (0.50). Limitations: In some studies, the patient groups were heterogeneous in terms of diagnosis. The studies varied depending on the joint into which the HA was administered. The synthesized studies differed with regard to the method of measuring the mandible abduction amplitude. Conclusions: The increase in the amplitude of mandibular abduction was expressed as the quotient of the mean values during the observation periods, and the initial value was achieved in all study groups, and in the linear regression model, it was 0.5 mm on average per month. Multiple administrations of the drug may reduce the analgesic effectiveness of the treatment.

Introduction: Fixing fractures of the base and neck of mandibular condyles is demanding due to the difficulties in surgical access and the various shapes of bone fragments. Classic fixation techniques assume the use of straight mini-plates, utilized for other craniofacial bone fractures. Three dimensional mini-plates may provide a reasonable alternative due to their ease of use and steadily improved mechanical properties. The multitude of different shapes of 3D mini-plates proves the need for their evaluation. Aim: This paper aims to summarize the clinical trials regarding the use of various types of 3D condylar mini-plates in terms of need for reoperation and the incidence of loosening and damage to the osteosynthetic material. Materials and Methods: A systematic review was conducted in accordance with PICOS criteria and PRISMA protocol. The risk of bias was assessed using ROBINS-I and RoB 2 Cochrane protocols. The obtained data series was analyzed for correlations (Pearson’s r) respecting statistical significance (Student’s t-test p > 0.05) and visualized using OriginLab. Results: 13 clinical trials with low overall risk of bias regarding 6 shapes of 3D mini-plates were included in the synthesis. The number of reoperations correlates with the number of fixations (r = 0.53; p = 0.015) and the total number of screw holes in the mini-plate (r = −0.45; p = 0.006). There is a strong correlation between the number of loosened osteosynthetic screws and the total number of fractures treated with 3D mini-plates (r = 0.79; p = 0.001 for each study and r = 0.99; p = 0.015 for each mini-plate shape). A correlation between the percentage of lost screws and the number of distal screw holes is weak regarding individual studies (r = −0.27; p = 0.000) and strong regarding individual mini-plate shape (r = −0.82; p = 0.001). Three cases of 3D mini-plate fractures are noted, which account for 0.7% of all analyzed fixation cases. Discussion: The reasons for reoperations indicated by the authors of the analyzed articles were: mispositioning of the bone fragments, lack of bone fragment union, secondary dislocation, and hematoma. The known screw loosening factors were poor bone quality, bilateral condylar fractures, difficulties in the correct positioning of the osteosynthetic material due to the limitations of the surgical approach, fracture line pattern, including the presence of intermediate fragments, and mechanical overload. Fractures of the straight mini-plates fixing the mandibular condyles amounts for up to 16% of cases in the reference articles. Conclusions: There is no convincing data that the number of reoperations depends on the type of 3D mini-plate used. The frequency of osteosynthetic screw loosening does not seem to depend on the 3D mini-plate’s shape. Clinical fractures of 3D mini-plates are extremely rare.

Background: Shots from commonly available non-gunpowder weapons are a significant cause of facial injuries, especially in pediatric patients. A consequence of such trauma may be the placement of a projectile within the maxillary sinus, which is a therapeutic need with no guidelines for foreign body removal. The purpose of this paper is to discuss the etiology, epidemiology, diagnosis, treatment and prognosis of such cases. Materials and methods: Any cases describing the presence of airgun pellets within the maxillary sinus were included. Animal patients and non-English cases were excluded. The final search using the PubMed, BASE and Google Scholar engines was made on 13 November 2021. The JBI Critical Appraisal Checklist for Case Reports was used to assess the risk of bias. The collected data are presented in tabular form and were subjected to a comparative assessment. Results: In total, reports of seven cases of lead airgun projectiles in the maxillary sinuses were identified, qualified and analyzed. There were no cases of lead intoxication. The bullets were removed by open surgery in the form of antrostomy of the maxillary sinus or with the use of an endoscope. In none of the described cases were complications observed during surgery or postoperative observation. Discussion: This systematic review was based on case reports that differed significantly in quality. The location of the lead foreign body within the maxillary sinuses may be considered favorable over other craniofacial gunshots. The risk of lead intoxication does exist, but such a location of the bullets does not favor it. The removal of projectiles from the maxillary sinuses appears to be easily achievable and does not predispose one to complications.