Evaluating mechanical and surface properties of zirconia-containing composites: 3D printing, subtractive, and layering techniques.

This study assessed the monotonic and fatigue flexural strength (FS), elastic modulus (E), and surface characteristics of a 3D printed zirconia-containing resin composite compared to subtractive and conventional layering methods. Specimens, including discs (n = 15; Ø = 15 mm × 1.2 mm) and bars (n = 15; 14 × 4 × 1.2 mm), were prepared and categorized into three groups: 3D printing (3D printing - PriZma 3D Bio Crown, Makertech), Subtractive (Lava Ultimate blocks, 3M), and Layering (Filtek Z350 XT, 3M). Monotonic tests were performed on the discs using a piston-on-three-balls setup, while fatigue tests employed similar parameters with a frequency of 10 Hz, initial stress at 20 MPa, and stress increments every 5000 cycles. The E was determined through three-point-bending test using bars. Surface roughness, fractographic, and topographic analyses were conducted. Statistical analyses included One-way ANOVA for monotonic FS and roughness, Kruskal-Wallis for E, and Kaplan-Meier with post-hoc Mantel-Cox and Weibull analysis for fatigue strength. Results revealed higher monotonic strength in the Subtractive group compared to 3D printing (p = 0.02) and Layering (p = 0.04), while 3D Printing and Layering exhibited similarities (p = 0.88). Fatigue data indicated significant differences across all groups (3D Printing < Layering < Subtractive; p = 0.00 and p = 0.04, respectively). Mechanical reliability was comparable across groups. 3D printing and Subtractive demonstrated similar E, both surpassing Layering. Moreover, 3D printing exhibited higher surface roughness than Subtractive and Layering (p < 0.05). Fractographic analysis indicated that fractures initiated at surface defects located in the area subjected to tensile stress concentration. A porous surface was observed in the 3D Printing group and a more compact surface in Subtractive and Layering methods. This study distinguishes the unique properties of 3D printed resin when compared to conventional layering and subtractive methods for resin-based materials. 3D printed shows comparable monotonic strength to layering but lags behind in fatigue strength, with subtractive resin demonstrating superior performance. Both 3D printed and subtractive exhibit similar elastic moduli, surpassing layering. However, 3D printed resin displays higher surface roughness compared to subtractive and layering methods. The study suggests a need for improvement in the mechanical performance of 3D printed material.

3D printed, subtractive, and conventional acrylic resins: Evaluation of monotonic versus fatigue behavior and surface characteristics.

This study assessed the mechanical properties and surface characteristics of dental prosthetic acrylic resin fabricated by 3D printing, comparing it with subtractive, pressing, and molding techniques. Bar-shaped specimens (N= 90; 65 × 10 × 3.3 mm; ISO:207951) were prepared and assigned into six groups: PRINT (3D printing vis stereolithography with PriZma 3D Bio Denture, Makertech Labs); SUB (subtractive manufacturing with Vipiblock Trilux, Vipi); PRESS Base (pressing using muffle with Thermo Vipi Wave, Vipi for base); PRESS Tooth (pressing with Onda-cryl, Clássico for tooth); MOLD Base (molding using addition silicone with Vipi Flash, Vipi for base); and MOLD Tooth (molding with Dencor, Clássico for tooth). Monotonic flexural strength (FS) and elastic modulus (E) were measured using a three-point bending approach (n= 5) on a universal testing machine at a crosshead speed of 5 mm/min. Fatigue testing (n= 10) followed similar geometry and settings, with a frequency of 2 Hz, initial stress level at 20 MPa, and stress increments of 5 MPa every 2,500 cycles. Surface roughness (n= 10) was assessed through profilometry, and fractographic and topographic analyses were conducted. Statistical analyses included One-Way ANOVA for monotonic FS, roughness, and E, along with Kaplan-Meier with Mantel-Cox post-hoc and Weibull analysis for fatigue strength. PRINT showed lower monotonic FS than the SUB and PRESS Tooth but comparable fatigue strength to these groups and superior to PRESS Base and MOLD (Base and Tooth) groups. All groups had similar Weibull moduli. Surface roughness of the PRINT group was comparable to most techniques but higher than the PRESS Tooth group. Fractographic analysis revealed fractures originating from surface defects under tensile stress, with SEM showing scratch patterns in all groups except PRINT, which had a more uniform surface. Despite its lower monotonic strength, 3D printed resin demonstrated comparable fatigue strength to subtractive and pressing methods and similar surface roughness to most methods, indicating its potential as a viable option for dental prosthesis.

Leg stiffness and muscle power vs manometer in sportswomen with symptoms of stress urinary incontinence.

BACKGROUND: Pelvic floor muscle training can cure or alleviate stress urinary incontinence. This study aimed to evaluate maximum voluntary contractions of the pelvic floor muscle in sportswomen and verify the association with leg stiffness and muscle power, both maximal and submaximal. METHODS: The sample consisted of 41 sportswomen between 18 and 42 years of age. Pelvic floor muscle strength was measured by the manometer. The sportswomen were instructed to perform 3 maximum voluntary contractions of the perineum, held for 3 seconds. Maximal and submaximal leg stiffness and muscle power were measured with a force platform, in two conditions: 1st condition was the sub-maximal, double leg hop test, which was performed allowing sportswomen to self-select their preferred frequency and 2nd condition was the maximal double leg hop test, which was performed asking athletes to maximize hop height and minimize contact time on the top of the force platform for 6 consecutive hops. FINDINGS: Maximal and submaximal leg stiffness values increase with increasing age, weight, height, and body mass index, showing positive and significant (p <0.05) or close correlations. There are strong positive correlations between maximal and submaximal leg stiffness (r = 0.759) and between maximal and submaximal muscle power. Maximum voluntary contractions values decrease with increasing leg stiffness: the correlation is significant with maximal leg stiffness. INTERPRETATION: Maximum voluntary contractions values decrease with increasing leg stiffness and increase with increasing muscle power values. If the training program aims to increase muscle power, it may also increase maximum voluntary contractions.

Effects of pelvic floor muscle training in pregnant women.

OBJECTIVE: The aim is to verify the effectiveness of the pelvic floor muscle training (PFMT) program in pregnant women, by analyzing the amount of urine leakage. DESIGN: Experimental study. LOCATION: Care units in the Vila Real district, Portugal. PARTICIPANTS: Forty-three pregnant women divided into an experimental group (EG) (n = 22) and a control group (CG) (n = 21). INTERVENTIONS: Both groups were evaluated in a predelivery stage (initial) and 6 months after delivery (final). The EG was given a PFMT exercise protocol with a duration of 6 weeks, applicable in classes and at home, another PFMT protocol for 9 weeks. MAIN MEASUREMENTS: The strength of the pelvic floor muscle was measured by the Oxford Grading Scale and the amount of urine was assessed with a Pad test. Quality of life was measured by the King's Health Questionnaire and self-efficacy by the Broome Pelvic Muscle Self-Efficacy Scale. RESULTS: The loss of urine, significantly reduced from 0.86 ±â€Š0.83 to 0.50 ±â€Š0.67 in the EG (P = .021), whereas in the CG no significant change was observed. The degree of muscle contraction increased by 4.82 ±â€Š0.39 in EG and 3.95 ±â€Š0.67 in CG. The quality of life observed significant improvements in both groups (P < .05). As for self-efficacy, for the EG it improved significantly - initial (P = .001), final (P = .031), and for the CG the values remained the same. CONCLUSIONS: This PFMT protocol reduced urinary incontinence in pregnant women. The program allowed significant improvement in the quantity of urinary leakage and an increase in the strength of the pelvic floor muscle.

Prevalence of Urinary Incontinence in High-Impact Sport Athletes: A Systematic Review and Meta-Analysis.

The aim of this study was to systematize the scientific evidence that assessed the prevalence of urinary incontinence in female athletes and determine which modality is most predisposed to stress urinary incontinence. From September to December 2018, a systematic literature search of current interventional studies of stress urinary incontinence of the last ten years was performed using PubMed, EMBASE, Scopus and Web of Science databases. The methodological quality was assessed by the Downs and Black scale, while the data collected from the studies were analyzed through meta-analysis. Nine studies met the eligibility criteria, meaning they included reports of urinary incontinence in different sports. The meta-analysis showed 25.9% prevalence of urinary incontinence in female athletes in different sports, as well as 20.7% prevalence of stress urinary incontinence. The most prevalent high impact sport was volleyball, with the value of 75.6%. The prevalence of urinary incontinence can be high in female athletes, with high-impact sports potentially increasing the risk for stress urinary incontinence. Further research is needed regarding the potential risk factors related to the onset of urinary incontinence.

Assessment of pelvic floor muscles in sportswomen: Quality of life and related factors.

OBJECTIVES: To evaluate Maximum Voluntary Contraction (MVC) of the Pelvic Floor Muscles (PFM) in sportswomen, to observe the urinary symptoms and their impact on the Quality of Life (QoL). DESIGN: Observational cross-sectional study. SETTING: Gyms and teams in the North of Portugal. PARTICIPANTS: Sportswomen (n = 197). MAIN OUTCOME MEASURES: The measurement was performed using a manometer. The sportswomen were instructed to perform 3 MVC of the perineum, held for 3 s. The Kings Health Questionnaire (KHQ) was used to evaluate urinary symptoms and the QoL of the sportswomen. RESULTS: Age significantly influenced (p < 0.05) the QoL in all domains. An increase in BMI was also significantly associated with a decrease in the QoL. MVC values had a highly significant effect on the overall QoL and all domains, including a reduction in urinary symptoms. The weekly time of physical activity was associated with a better QoL in symptomatology. The practice of high-impact activities decreased the QoL (compared to low-impact activities). The vaginal resting pressure values ranged from 1.60 to 59.80 (24.34 ± 11.00). CONCLUSIONS: Age, BMI and high-impact sports appear to be the leading factors that promote the onset of SUI, which in turn decrease the QoL in sportswomen. There was a positive association between MVC and weekly time of physical activity in the QoL.

Pelvic Floor Muscle Training in Female Athletes: A Randomized Controlled Pilot Study.

The aim of this study was to investigate the effects of pelvic floor muscles training in elite female volleyball athletes and whether it is an effective therapy for stress urinary incontinence. Fourteen athletes, both continent and incontinent, between 18 and 30 years of age, were randomly assigned to an experimental group or a control group. The experimental group received a protocol for pelvic floor muscle training for 4 months. This consisted of three phases: awareness/stabilization, strength training and power. The control group was not subject to any intervention during the same period. Measures were collected at the initial and final phase for both groups. Maximum voluntary contractions were evaluated with a perineometer, involuntary urine loss with a Pad test and quality of life with the King's Health Questionnaire. Baseline sociodemographic and anthropometric characteristics were not significantly different. Comparing the two groups, the experimental group improved maximum voluntary pelvic contractions (p<0.001) and reduced urine loss (p=0.025), indicating the existence of significant differences between groups in the variation from the initial and final phases. The percentage of urine loss decreased in the experimental group, from 71.4-42.9%, suggesting that the protocol intervention for 16 weeks may help athletes with stress urinary incontinence.