Effects of La2O3 contents on microstructure and properties of laser-cladded 5wt%CaB6/HA bioceramic coating

In the present work, 5wt%CaB6/HA bioceramic coatings with different La2O3contents (0-0.6wt%) have been fabricated by a laser cladding technique on Ti-6Al-4V. The effects of La2O3 contents on microstructure and properties of the laser-cladded 5wt%CaB6/HA coatings have been carefully investigated. The results show that the microstructure is obviously refined, and the structure is relatively uniform after doping 0.2-0.4 wt% La2O3. As the La2O3 content increases, the corrosion resistance are found to increase firstly and then gradually decrease. The XRD analysis confirms that the amount of HA and TCP in the coating reaches maximum after doping 0.2wt% La2O3. The La2O3-doped coatings show a significantly higher bone-like apatite precipitation after immersion in SBF compared with La2O3-free coating. In vitro experiment also shows that 5wt%CaB6/HA bioceramic coatings with 0.2-0.4wt% La2O3 are more suitable for the attachment and proliferation of MG63 cells, exhibiting superior bioactivity and biocompatibility.

The Contrasting Effects between Caffeine and Theobromine on Crystallization: How the Non-fluoride Dentifrice Was Developed

Caffeine and theobromine are members of the xanthine family. Coffee and soft drinks contain caffeine, whereas, in cacao, theobromine is the main ingredient. The mineral contents of the tooth which sucked the caffeine-containing dam’s milk were decreased. To determine if caffeine would affect enamel, dams were fed with a caffeine and pups were killed and first and second molars were extracted. Enamel was exposed to the acid solution and dissolved minerals from the enamel were measured. Calcium, phosphorus and magnesium from the first molars of the caffeine group were significantly dissolved. To determine why minerals were released, enamel was separated. The crystallite size of the enamel from the caffeine group showed decreased. If the pups with the same dietary regimen, but given a cariogenic diet, the caffeine group should show a higher incidence of dental caries. The caffeine group revealed higher caries scores. An in vitro experiment to grow apatite crystals was conducted, adding the various members of the xanthine. Theobromine produced larger crystal sizes than caffeine. Theobromine was added to the maternal diet. Dissolution experiments revealed that these minerals were far less dissolved. Comparative studies of the various parameters between theobromine and fluoride were conducted. Theobromine was superior to fluoride in every aspect.

Effect of Roller Pump Pulse in the Arterial Needle Area during Hemodialysis

Vascular access is a lifeline for hemodialysis patients. Its lifetime is affected by many hemodynamic factors such as pressure, flow regime and wall shear stress. During hemodialysis, changes in hemodynamic parameters occur due to the flow from needles inserted into the vascular system. Primarily, there is a change in shear stress that affects the vascular wall. Pathological effects of high or low WSS are known. The effect of jet from a venous needle on hemodynamics parameters was studied, but the influence of the arterial needle on hemodynamics parameters is not sufficiently studied. To understand its possible effects, we performed in vivo and in vitro studies. Methods. In vivo experiment: The existence of flow reversal around the suction needle was visualized in a group of 12 randomly selected patients using ultrasound velocity profiling (Doppler ultrasonography) during hemodialysis. In vitro experiment: The flow field was measured using the stereo particle image velocimetry method (stereo PIV). Two regimes were studied. In the first regime, the fluid in the extracorporeal circuit was pumped by a peristaltic pump. In the second regime, the continuous pump was used in the extracorporeal circuit. The conditions were set to resemble those in vascular access during a hemodialysis session. Flow volume was set to 600 mL/min for vascular access and 200 mL/min for the extracorporeal circuit. Results. The main finding of this study was that the wall in the region of the arterial needle was stressed by backflow through the arterial needle. Since this was a variable, low-shear stress loading, it was one of the risk factors for the development of stenosis. Cyclic flow reversal was apparent in all of the included hemodialysis patients. The stereo PIV in vitro experiment revealed the oscillating character of wall shear stress (WSS) inside the model. High shear stress was documented upstream of the injection point of the arterial needle. An area of very low WSS was detected right behind the injection point during a pulse of the peristaltic pump. The minimal and maximal values of the WSS during a pulse of the peristaltic pump in the observed area were −0.7 Pa and 6 Pa, respectively. The distribution of wall shear stress with the continual pump used in the extracorporeal circuit was similar to the distribution during a pulse of the peristaltic one. However, the WSS values were continual; the WSS did not oscillate. WSS ranged between 4.8 Pa and 1.0 Pa.

ANTIMICROBIAL EFFECT OF A MEANS FOR ENZYME EXCAVATION (BRIX 3000) AND PHOTODYNAMIC THERAPY IN CARIOUS LESIONS OF PRIMARY TEETH – IN VITRO EXPERIMENT

The selective removal of the caries dentin via enzyme methods for excavation appears to be an alternative to the conventional treatment of carious lesions in childhood. Photodynamic therapy is an effective alternative for the reduction of cariesogenic microorganisms. Brix 3000 is an enzyme-based material for excavation of carious dentin. Aim: To study the antimicrobial effect of means for enzyme excavation (Brix 3000) and photodynamic therapy with FotoSan 630 Intro Kit to the two main cariesogenic microorganisms – S. mutans and L. acidophilus, in vitro experiment; Materials and Methods: Eighty plates were prepared: group 1- 20 plates only with Brix 3000; group2 – 20 plates only with FotoSan; group 3 – 20 plates with a combination of Brix 3000 and FotoSan; group 4 – 20 plates without an active agent. In the agar of each plate, three 7 mm wells in diameter were made, where the Brix 3000 gel was placed, as well as discs soaked with the dye and irradiated with FotoSan and a combination of them. After 24 hours, the zone of inhibition was measured. Results: Compared to the control group, Brix 3000 and FotoSan have a defined antimicrobial activity against S. mutans and Lactobacillus spp. By combining the two materials, their antimicrobial activity significantly increases. S. mutans shows greater resistance compared to Lactobacillus spp. Conclusion: A combination of enzyme-based excavation and photodynamic therapy could be used successfully in the treatment of carious lesions in primary teeth.