Vertical jump neuromuscular performance of professional female handball players-starters vs. non-starters comparison.

Given the complex nature of the handball as a game, players are required to possess a distinct set of physical and physiological attributes to attain peak performance. With the countermovement vertical jump (CVJ) being widely implemented as a non-invasive and time-efficient testing modality in sports settings, the purpose of the present study was twofold: (a) to establish a CVJ profile of professional female handball players and (b) to examine differences in force-time metrics between starters and non-starters. Forty-two professional female handball players (e.g., SuperLeague) volunteered to participate in this study. Each athlete performed three maximum-effort CVJs with no arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. Independent t-tests were used to examine differences in each variable between starters and non-starters. The results revealed that starters attained superior performance within the eccentric phase of the CVJ when compared to non-starters, particularly in terms of eccentric peak velocity (-0.957 ± 0.242 vs. -0.794 ± 0.177 m·s-1), eccentric mean power (320.0 ± 77.7 vs. 267.1 ± 75.2 W), and eccentric peak power (929.0 ± 388.1 vs. 684.4 ± 214.2 W). While not reaching the level of statistical significance, moderate-to-large effect sizes were observed for concentric impulse, peak velocity, and mean and peak force and power, all in favor of players included in the starting lineup (g = 0.439-0.655). Overall, these findings suggest that at the top-tier level of handball competition, the ability to secure a spot in a starting lineup may be possibly influenced by the athlete's eccentric performance capabilities. Thus, the development of lower-body eccentric strength and power may positively impact on-court athlete performance and ultimately help the team secure the desired game outcome.

Experimental Investigation of the Biofunctional Properties of Nickel-Titanium Alloys Depending on the Type of Production.

Nickel-titanium alloys used in dentistry have a variety of mechanical, chemical, and biofunctional properties that are dependent on the manufacturing process. The aim of this study was to compare the mechanical and biofunctional performances of a nickel-titanium alloy produced by the continuous casting method (NiTi-2) with commercial nitinol (NiTi-1) manufactured by the classical process, i.e., from remelting in a vacuum furnace with electro-resistive heating and final casting into ingots. The chemical composition of the tested samples was analyzed using an energy dispersive X-ray analysis (EDX) and X-ray fluorescence (XRF). Electron backscatter diffraction (EBSD) quantitative microstructural analysis was performed to determine phase distribution in the samples. As part of the mechanical properties, the hardness on the surface of samples was measured with the static Vickers method. The release of metal ions (Ni, Ti) in artificial saliva (pH 6.5) and lactic acid (pH 2.3) was measured using a static immersion test. Finally, the resulting corrosion layer was revealed by means of a scanning electron microscope (SEM), which allows the detection and direct measurement of the formatted oxide layer thickness. To assess the biocompatibility of the tested nickel-titanium alloy samples, an MTT test of fibroblast cellular proliferation on direct contact with the samples was performed. The obtained data were analyzed with the IBM SPSS Statistics v22 software. EDX and XRF analyses showed a higher presence of Ni in the NiTi-2 sample. The EBSD analysis detected an additional NiTi2-cubic phase in the NiTi-2 microstructure. Additionally, in the NiTi-2 higher hardness was measured. An immersion test performed in artificial saliva after 7 days did not induce significant ion release in either group of samples (NiTi-1 and NiTi-2). The acidic environment significantly increased the release of toxic ions in both types of samples. However, Ni ion release was two times lower, and Ti ion release was three times lower from NiTi-2 than from NiTi-1. Comparison of the cells' mitochondrial activity between the NiTi-1 and NiTi-2 groups did not show a statistically significant difference. In conclusion, we obtained an alloy of small diameter with an appropriate microstructure and better response compared to classic NiTi material. Thus, it appears from the present study that the continuous cast technology offers new possibilities for the production of NiTi material for usage in dentistry.

Salivary VEGF and post-extraction wound healing in type 2 diabetic immediate denture wearers.

OBJECTIVE: Oral wound healing in healthy could be promoted by VEGF in saliva, and immediate denture wearing, but data in type 2 diabetes are lacking. Aims were to investigate the timeline of extraction wound healing in diabetic participants wearing immediate dentures and its correlation to salivary VEGF, as well as to examine the impact of the palatal plate on tissue VEGF during palatal wound healing in rat diabetic model. MATERIAL AND METHODS: Healthy (42) and type 2 diabetic (36) denture wearers, candidates for teeth extractions were included. Extraction wound healing was followed via measurements of socket closure, gingival hyperaemia, pain and presence of necrosis on 3rd, 7th, 14th and on 21st-day post-extraction. Salivary VEGF was measured before and on the 3rd and 21st day after the extraction. In streptozotocin-induced diabetic (30) as well as non-diabetic rats (30), tissue VEGF was measured in palatal wounds healing under or without a palatal plate. RESULTS: Type 2 diabetic prosthetic patients exhibit delayed socket closure, with pronounced hyperaemia, pain and necrosis. Salivary VEGF is increased in diabetes and positively correlates to socket closure while negatively with pain on 21st day after the extraction. Palatal incision induced VEGF increase in non-diabetic and diabetic, but less pronounced in diabetic rats. Wound healing under the palatal plate exhibit higher tissue VEGF. CONCLUSION: Type 2 diabetes-induced increase in salivary VEGF may mitigate diabetes-induced detrimental effects on extraction wound healing. Lack of adequate tissue VEGF response to injury may underly dysregulation of diabetic oral wound healing.

The effect of COVID-19 pandemic on final year dental students' self-confidence level in performing clinical procedures.

BACKGROUND: The outbreak of COVID-19 pandemic in 2020 has dramatically changed teaching approach in dental schools due to the switch to distance learning and the lack of practice training in direct contact with patients with possible impact on clinical skills of students. The aim of the study was to assess the level of the 2020 final year dental students' self-confidence in performing different dental procedures through specially designed questionnaire and compare it to self-confidence of the 2019 final year students. MATERIALS AND METHODS: An anonymous questionnaire consisting of 40 questions regarding self-confidence level in performing 40 different dental procedures and based on five points Likert-like scale was distributed during November 2020 to final year dental students whose studies were disrupted by the COVID-19 pandemic lockdown in one semester. The study group comprised their answers. The comparison was done with the control group that consisted of students' answers on the same questionnaire from previous 2019 year conducted as a part of regular internal educational evaluation. RESULTS: Response rate was 74.2% in study group and 89.3% in control group. Mean level of self-confidence reported by 115 students in study group was significantly lower than that reported by 100 students in control group (3.28±1.08 vs. 3.58±0.88, respectively) and the distribution of self-confidence scores were different in observed groups. Graduates from study group felt less confident than those from control in 8 clinical skills. CONCLUSION: Abrupt changes in teaching modalities caused by COVID-19 pandemic had significant impact on final year dental students' self-confidence indicating additional educational needs in postgraduate period.

The use of digital texture image analysis in determining the masticatory efficiency outcome.

The mixture level of gum samples consisting of two colours can be assessed visually, using the electronic colorimetric method, employing digital image processing techniques and specially designed software. The study investigates the possibility of an alternative method called "digital texture image analysis" (DTIA) to assess improvement of masticatory efficiency in denture wearers. The objectives were i) to evaluate whether DTIA discriminates changes in the colour mixing ability within a group over time; ii) to determine whether DTIA can be used to detect improvement in chewing ability; iii) to select the most appropriate DTIA feature that sufficiently describes masticatory efficiency in CDs wearers. The study was designed as an intra-individual evaluation of masticatory efficiency, which was assessed in participants with new dentures in three follow-up times. A set of four texture features was used in the current study. Uniformity, Contrast, Homogeneity and Entropy of the obtained chewing-gum samples were correlated to the degree of gum comminution. A statistically significant difference in masticatory efficiency was observed based on the values of the analysed DTIA variables of gum samples-Uniformity, Contrast, Homogeneity, and Entropy-have changed in the participants during the observation period. The improvement of the masticatory function in relation to the mixing ability of two-coloured chewing gum could be traced by monitoring changes in the values of DTIA variables. The most increasement of masticatory efficiency was observed by monitoring DTIA parameters such as contrast, and homogeneity.

The effect of recasting on biological properties of Ni-Cr dental alloy.

Introduction: Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and acceptable prices, have found their place in everyday dental practice. However, within the procedure of making dental prosthetic restorations, the alloys are melted and cast, which leads to changes in their physical, mechanical and biological properties. Objective: The objective of the study was to test biocompatibility of a Ni-Cr dental alloy (WIRON 99) depending on the number of melting and casting processes. Methods: The working method included the testing of cytotoxicity of the alloy obtained by casting after one, after four, and after eight successive processes of melting. Cytotoxicity of samples was tested by means of a 24-hour and a three-day cytotoxicity test, done on L929 fibroblasts. Results: A repeatedly melted and cast alloy shows a reduced biocompatibility and causes specific responses of the tissues in the surrounding area. Since the cytotoxic effect is more significant in the extended contact with the culture cells, a three-day cytotoxicity test showed discrete changes which were the indicator of cell growth inhibition in the cell culture. Conclusion: The obtained results confirm the working hypothesis that repeated alloy melting and casting will decrease biocompatibility of dental alloys and will lead to specific responses of the tissue in the surrounding area.

Denture stomatitis and salivary vascular endothelial growth factor in immediate complete denture wearers with type 2 diabetes.

STATEMENT OF PROBLEM: Diabetes mellitus type 2 is associated with a variety of oral mucosal changes, including an altered level of salivary vascular endothelial growth factor. However, the authors identified no studies concerning denture stomatitis and salivary vascular endothelial growth factor in immediate denture wearers with diabetes mellitus type 2. PURPOSE: The purpose of this study was to investigate the incidence of and risk factors for denture stomatitis in immediate complete denture wearers with and without diabetes mellitus type 2 and to investigate the relationship between levels of salivary vascular endothelial growth factor and clinical forms of denture stomatitis in both groups. MATERIAL AND METHODS: Individuals without diabetes (n=42) or with diabetes mellitus type 2 (n=36) who were candidates for complete immediate dentures were included in the study. After 1 year of wearing relined immediate dentures, participants were evaluated for denture stomatitis and potential contributing factors. Salivary vascular endothelial growth factor levels were measured with enzyme-linked immunosorbent assays. Data were analyzed with the χ(2) test or the Student t test where appropriate, as well as with binary logistic regression analysis. RESULTS: The incidence of denture stomatitis was 61% in participants with diabetes mellitus type 2 and 38% in those without diabetes. Low denture stability and diabetes mellitus type 2 were risk factors for denture stomatitis. Salivary vascular endothelial growth factor concentrations at the beginning of the study were 557.6 ±94.7 pg/mL in participants with diabetes mellitus type 2 and 103.5 ±21.6 pg/mL in those without diabetes. In Newton Type I and Newton Type II denture stomatitis, vascular endothelial growth factor levels were 460.9 ±55.4 pg/mL and 1445.2 ±422.1 pg/mL in individuals with diabetes and 73.2 ±10.0 pg/mL and 306.5 ±22.6 pg/mL in those without diabetes. CONCLUSIONS: Perceived denture stability and diabetes mellitus type 2 are independent risk factors for the occurrence of denture stomatitis. Altered salivary vascular endothelial growth factor levels and denture stomatitis are more prevalent in denture wearers with diabetes mellitus type 2.

Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements.

BACKGROUND/AIM: Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the behaviour of unilateral complex partial denture supporting structures. METHODS: Stress levels of the canine and the first premolar as retentional teeth and the attachments were tested under the influence of physiological forces with the loading point shifting distally in relation to the saddle length change. A virtual real size 3D model of the fixed part of the restoration (the canine and the first premolar with milled crowns) was created using the CATIA computer program. It was connected to the mobile part of partial denture with the SD snap in latch attachment. Mobile part of the restoration was designed in the region of 2, 3 and 4 lateral teeth (second premolar, first, second and third molar). By using the finite element method (FEM) stress levels analysis was performed under the load of physiological forces of 150 N in the free-end saddle teeth zone. RESULTS: The results of analysis show that physiological forces cause a different stress distribution on the abutment teeth and the attachment, depending on the saddle length. CONCLUSION: The stress level values obtained for the abutment teeth as well as the attachment are far lower than the marginal ones. The behaviour of the system changes under this defined stress, but no plastic deformation occurs.

The levels of vascular endothelial growth factor and bone morphogenetic protein 2 in dental pulp tissue of healthy and diabetic patients.

INTRODUCTION: Vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP 2) are growth factors (GFs) identified within the dentine-pulp complex and involved into the cellular events connected to the pulp-healing response. It is well established that the expression of these GFs is increased in different tissues in diabetes mellitus. Because there are no data concerning the levels of VEGF and BMP 2 in human dental pulp, the aim of present study was to quantify VEGF and BMP 2 levels in intact dental pulp and dental pulp that underwent reactive dentinogenesis in healthy and diabetic human subjects. METHODS: The study was conducted on 28 healthy and 28 subjects with controlled diabetes type II who underwent pulp extirpation as a part of prosthetic rehabilitation. Pulp were collected from intact teeth and teeth treated by indirect pulp capping. The levels of VEGF and BMP 2 were determined in the pulp tissue lysates with enzyme-linked immunosorbent assay. RESULTS: The levels of VEGF and BMP 2 were significantly higher in intact teeth pulp of diabetic than in healthy subjects. The concentrations of these GFs were significantly lowered in teeth with indirect pulp capping both in healthy and diabetic persons. Furthermore, VEGF and BMP 2 levels were in strong positive correlation. CONCLUSIONS: Similar changes in the levels of VEGF and BMP 2 in intact and treated teeth of healthy and diabetic patients could be suggestive of associated roles of these GFs in responses of healthy and diabetic dental pulp.

[Comparative analysis of unilateral removable partial denture and classical removable partial denture by using finite element method].

INTRODUCTION: Various mobile devices are used in the therapy of unilateral free-end saddle. Unilateral dentures with precise connectivity elements are not used frequently. In this paper the problem of applying and functionality of unilateral free- end saddle denture without major connector was taken into consideration. OBJECTIVE: The aim was to analyze and compare a unilateral RPD (removable partial denture) and a classical RPD by calculating and analyzing stresses under different loads. METHODS: 3D models of unilateral removable partial denture and classical removable partial denture with casted clasps were made by using computer program CATIA V5 (abutment teeth, canine and first premolar, with crowns and abutment tissues were also made). The models were built in full-scale. Stress analyses for both models were performed by applying a force of 300 N on the second premolar, a force of 500 N on the first molar and a force of 700 N on the second molar. RESULTS: The Fault Model Extractor (FME) analysis and calculation showed the complete behaviour of unilateral removable partial denture and abutments (canine and first premolar), as well as the behaviour of RPD under identical loading conditions. Applied forces with extreme values caused high stress levels on both models and their abutments within physiological limits. CONCLUSION: Having analyzed stresses under same conditions, we concluded that the unilateral RPD and classical RPD have similar physiological values