The connection structure of zirconia dental implants significantly influences their biomechanical behavior and plays a crucial role in the overall service performance of the implant system. This study aims to compare the stress distribution of zirconia implants featuring various internal connection structures under different working conditions. Four distinct types of connection structures were designed for zirconia dental implants: triangular, quadrilateral, hexagonal, and hexalobular plus connections. Additionally, the finite element method was employed to analyze these structures under three working conditions: a static load test model, a bone level model, and a torsion model. Results indicated that in the static load test model, the hexagonal structure experienced the highest stress value at 1284.9 MPa due to its thin neck wall, whereas the hexalobular plus connected implant exhibited the lowest stress value at 1252.9 MPa. In the bone level model, the triangular connection structure demonstrated poor stress distribution for cortical bone and cancellous bone at 69.606 MPa and 7.8191 MPa, respectively. Conversely, the hexalobular plus connection yielded superior stress results for cortical bone and cancellous bone, with values of 66.24 MPa and 5.1327 MPa, respectively. In the torsion model, the hexalobular plus-connected implant exhibits the highest stress value at 237.6 MPa, while maintaining the smallest force transmission angle. Therefore, given that the abutment necessitates a greater range of installation angles and improved torque transmission, the hexalobular plus connection structure may represent the optimal choice.
- Klíčová slova
- Connection structure, Dental implant, FEA, Zirconia,
- MeSH
- analýza metodou konečných prvků * MeSH
- biomechanika MeSH
- mechanické jevy MeSH
- mechanické testy MeSH
- mechanický stres * MeSH
- testování materiálů * MeSH
- zirkonium * chemie MeSH
- zubní implantáty * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- zirconium oxide MeSH Prohlížeč
- zirkonium * MeSH
- zubní implantáty * MeSH
STATEMENT OF PROBLEM: Fatigue failure of implant components is a common clinical problem. Plasma nitriding, an in situ surface-strengthening method, may improve fatigue properties of dental implants. PURPOSE: The purpose of this in vitro study was to evaluate the effect of plasma nitriding on the fatigue behavior of implant systems. MATERIAL AND METHODS: The preload and friction coefficient of plasma nitrided abutment screws, as well as settlement of the implant-abutment interface, were measured. Then, the reverse torque values and pullout force were evaluated after cyclic loading. Finally, the fatigue properties of the implant system were investigated with static fracture and dynamic fatigue life tests, and the morphology of the fracture on the surface of the implant system was observed. RESULTS: The plasma nitriding treatment reduced the friction coefficient; increased the preload, settlement value, reverse torque values, pullout force, and static fracture load; and prolonged fatigue life. Furthermore, abutment screws with plasma nitriding treatment showed a different fatigue fracture mode. CONCLUSIONS: Plasma nitriding improved mechanical performance and may be a suitable way to optimize the fatigue behavior of dental implants.
- MeSH
- analýza zatížení zubů metody MeSH
- design pilíře zubního implantátu MeSH
- podpěry zubní MeSH
- testování materiálů MeSH
- točivý moment MeSH
- tření MeSH
- zubní implantáty * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- zubní implantáty * MeSH
OBJECTIVES: To investigate the reliability of the OMERACT US Task Force definition of US enthesitis in SpA. METHODS: In this web exercise, based on the evaluation of 101 images and 39 clips of the main entheses of the lower limbs, the elementary components included in the OMERACT definition of US enthesitis in SpA (hypoechoic areas, entheseal thickening, power Doppler signal at the enthesis, enthesophytes/calcifications, bone erosions) were assessed by 47 rheumatologists from 37 rheumatology centres in 15 countries. Inter- and intra-observer reliability of the US components of enthesitis was calculated using Light's kappa, Cohen's kappa, Prevalence And Bias Adjusted Kappa (PABAK) and their 95% CIs. RESULTS: Bone erosions and power Doppler signal at the enthesis showed the highest overall inter-reliability [Light's kappa: 0.77 (0.76-0.78), 0.72 (0.71-0.73), respectively; PABAK: 0.86 (0.86-0.87), 0.73 (0.73-0.74), respectively], followed by enthesophytes/calcifications [Light's kappa: 0.65 (0.64-0.65), PABAK: 0.67 (0.67-0.68)]. This was moderate for entheseal thickening [Light's kappa: 0.41 (0.41-0.42), PABAK: 0.41 (0.40-0.42)], and fair for hypoechoic areas [Light's kappa: 0.37 (0.36-0.38); PABAK: 0.37 (0.37-0.38)]. A similar trend was observed in the intra-reliability exercise, although this was characterized by an overall higher degree of reliability for all US elementary components compared with the inter-observer evaluation. CONCLUSIONS: The results of this multicentre, international, web-based study show a good reliability of the OMERACT US definition of bone erosions, power Doppler signal at the enthesis and enthesophytes/calcifications. The low reliability of entheseal thickening and hypoechoic areas raises questions about the opportunity to revise the definition of these two major components for the US diagnosis of enthesitis.
- Klíčová slova
- PsA, enthesitis, multicenter international study, power Doppler signal, reliability, seronegative spondyloarthritis, ultrasound,
- MeSH
- entezopatie * diagnostické zobrazování MeSH
- internet MeSH
- lidé MeSH
- reprodukovatelnost výsledků MeSH
- ultrasonografie dopplerovská metody MeSH
- ultrasonografie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
Screw loosening is one of the most common clinical problems of dental implants. Research on the influencing factors of screw loosening is very important to prevent screw loosening. The purpose of this in vitro study was to evaluate the influence of liquid contamination on the screw loosening. According to the contamination condition, forty-five abutment screws were divided into three groups (n = 15): no contamination, artificial saliva contamination, and mouthwash contamination. The preload and friction coefficient of the abutment screws were recorded. Then, the reverse torque values (RTVs) and settlement were measured after 3.0 × 105 and 6.0 × 105 cycles. The surface wear of the screws was analyzed. Finally, the stress distribution of the abutment screws was calculated by finite element analysis (FEA). The results showed that fluid contamination reduced the friction coefficient, increased the preload, decrease the settlement, improved resistance to screw loosening, and reduced wear on the thread surface. Appropriate antimicrobial lubrication may improve the anti-loosening performance of abutment screws and prevent excessive wear on the threaded surface.
- MeSH
- analýza metodou konečných prvků MeSH
- kostní šrouby * MeSH
- lubrikace MeSH
- točivý moment MeSH
- tření MeSH
- zubní implantáty * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- zubní implantáty * MeSH
Biomechanical performance plays an important role in the long-term service of dental implants. Loosening and fatigue damage of the central screw are the most common problems. This research investigated the effect of the central screw taper angle on the loosening performance and fatigue characteristics of dental implants. Central screws with four taper angles, 30°, 60°, 90° and 180°, were processed and tested. The loosening performance of the screws under initial and postload conditions was compared. Then, the fatigue characteristics of dental implants was measured. Finally, the wear and fracture modes of the screws were observed. The damage locations were verified by finite element analysis (FEA). The results showed that the central screws with 30° taper had substantially better anti-loosening performance and less fretting wear. The central screws with 180° taper had a higher preload, resulting in a longer fatigue life. Furthermore, the fatigue fracture of the central screw occurred at the level of the first thread position, consistent with the FEA results. In the future clinical applications, central screws with a 30° taper angle may improve anti-loosening performance and prolong fatigue life by increasing the tightening torque.
- Klíčová slova
- Central screw, Dental implant, Fatigue damage, Fretting wear, Screw loosening,
- MeSH
- analýza metodou konečných prvků MeSH
- analýza zatížení zubů MeSH
- kostní šrouby MeSH
- točivý moment MeSH
- zubní implantáty * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- zubní implantáty * MeSH
BACKGROUND: Secukinumab demonstrated sustained efficacy in patients with ankylosing spondylitis (AS) through 5 years in pivotal Phase III studies. Here, we present efficacy and safety results (52-week) of secukinumab in patients with AS from the MEASURE 5 study. METHODS: MEASURE 5 was a 52-week, Phase III, China-centric study. Eligible patients were randomly assigned (2:1) to receive subcutaneous secukinumab 150 mg or placebo weekly for the first five doses and then once every 4 weeks (q4w). All placebo patients switched to secukinumab 150 mg q4w starting at Week 16. Primary endpoint was Assessments of SpondyloArthritis international Society (ASAS) 20 at Week 16. Randomization was stratified by region (China vs. non-China). RESULTS: Of 458 patients (secukinumab 150 mg, N = 305; placebo, N = 153) randomized, 327 (71.4%) were from China and 131 (28.6%) were not from China. Of these, 97.7% and 97.4% patients completed Week 16 and 91.1% and 95.3% (placebo-secukinumab) patients completed Week 52 of treatment. The primary endpoint was met; secukinumab significantly improved ASAS20 response at Week 16 vs. placebo (58.4% vs. 36.6%; P < 0.0001); corresponding rate in the Chinese population was 56.0% vs. 38.5% (P < 0.01). All secondary efficacy endpoints significantly improved with secukinumab 150 mg in the overall population at Week 16; responses were maintained with a trend toward increased efficacy from Week 16 to 52. No new or unexpected safety signals were reported up to Week 52. CONCLUSIONS: Secukinumab 150 mg demonstrated rapid and significant improvement in signs and symptoms of AS. Secukinumab was well tolerated and the safety profile was consistent with previous reports. Efficacy and safety results were comparable between the overall and Chinese populations. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02896127; https://clinicaltrials.gov/ct2/show/NCT02896127?term=NCT02896127&draw=2&rank=1.
- MeSH
- ankylózující spondylitida * farmakoterapie MeSH
- dvojitá slepá metoda MeSH
- humanizované monoklonální protilátky MeSH
- lidé MeSH
- monoklonální protilátky terapeutické užití MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky, fáze III MeSH
- randomizované kontrolované studie MeSH
- Geografické názvy
- Čína MeSH
- Názvy látek
- humanizované monoklonální protilátky MeSH
- monoklonální protilátky MeSH
- secukinumab MeSH Prohlížeč
