ABSTRACT
The repair of bone defects poses a great challenge for reconstructive surgeons. Although the development of tissue engineering has exhibited promise in replacing damaged bone, the fabrication of large constructs with functional blood vessels remains an obstacle. From the orthopedic surgeon's point of view, the generation of axially vascularized bone, which can anastomose with the recipient vessel, might be a solution to this medical problem. In this study, we aimed to prefabricate an axially vascularized bone by combining a β-TCP scaffold, arteriovenous loop (AVL), and cell sheet in a bioreactor in vivo. Twelve rabbits were randomly allocated into two groups: the experimental group (presence of AVL) and the control group (absence of AVL). The constructs were explanted at 8 weeks postoperatively. The histomorphometric results showed 42.8±5.9% of the bone area in the AVL group and 26.6±3.5% in the control group. Similarly, vessel analysis revealed the average vessel density in the AVL group (12.5±3.3) was significantly more than that in the control group (6.1±1.5, p<0.05). Our research indicated that the combination of a β-TCP scaffold, AVL and cell sheet might engineer vascularized bone. This prefabrication strategy might facilitate clinical translation of bone tissue engineering in reconstructing large bone defects.
Subject(s)
Rabbits , Bioreactors , Blood Vessels , Bone and Bones , Orthopedics , Surgeons , Tissue EngineeringABSTRACT
Objective; To evaluate the influence of electrolyte's concentration at micro-arc oxide treatment on the bonding strength of titanium to porcelain. Methods; CP titanium specimens with size of 25 mm ×3 mm ×0. 5 mm were treated with micro-arc oxidation (MAO) in Na_2SiO_3 solution of three different concentrations. After ultra-low-fusing porcelain was applied, a three-point-flexure-test was used to evaluate the bonding strength of titanium to porcelain. The surface of the specimens was observed by SEM and EDS, as well as the interface between titanium and porcelain. Results; The bonding strength values between titanium treated with MAO and porcelain was significantly higher then the control groups, Croup 20 g/L has the highest bonding strength values. SEM/EDS suggested that a porous thin layer of oxide which contains Si element is created by MAO, and higher concentration of Na_2SiO_3 leads to more Si element in oxide. Conclusion; MAO treating can improve the bonding strength between titanium and ceramic. Electrolyte's concentration has an effect on the bond strength between titanium and porcelain.
ABSTRACT
Objective To evaluate the curative effects of the modified fixed reverse Twin-block ap-pliance (TBA)combined Edgewise in the treatment of adult Angle Ⅲ anterior crossbite. Methods The appliance was used in 18 subjects with adult Angle Ⅲ skeletal malocclusion and clinical characters and X-ray cephalometry were then compared before and after treatment. Results The mandibular soft tissue changes could be achieved fast and the profile had changed effectively. Moderate labioclination of maxil-lary anterior teeth played a role in the improvement of axillary soft tissue protrusion. The cases were fol-lowed up as long as 3 years. No relapse occurred in all the patients. Anterior occlusion was normal. Con-clusion All findings indicate that adult Angle Ⅲ anterior crossbite can be quickly corrected with the mod-ified fixed reverse TBA combined Edgewise. The effect on mandibular soft tissue is significant.
ABSTRACT
Objective:To study the effects of duty cycle and frequency of microarc oxidation(MAO) on the titanium ceramic bonding strength.Methods:Titanium samples were treated with MAO in a Na2SiO3 electrolytic solution with voltage 300 V?3 min. According to the different duty cycle and frequency,experimental groups were named as:group Ⅰ(0.2, 500 Hz); group Ⅱ(0.2, 1 000 Hz); group Ⅲ(0.04,1 000 Hz); group Ⅳ(0.04,500 Hz) and group Ⅴ(0.12,750 Hz). The non-MAO samples were used as a control group.The surface of the samples was observed by scanning electron microscope (SEM).The samples were bonded to porcelain,and the bonding strength was measured by a three point bending test according to ISO 9693.Results:The surfaces of 1 000 Hz test pieces were smaller holes,more holes in the number and thicker layer than that of 500 Hz. When measured the bonding strength(MPa) of the samples, group Ⅳ was higher than group Ⅲ(P