The purpose of this study was to evaluate skeletal and dental effects of bionator headgear combination appliances on patients in development period with Class Ⅱ, division 1 malocclusion. The comparison of computerize...The purpose of this study was to evaluate skeletal and dental effects of bionator headgear combination appliances on patients in development period with Class Ⅱ, division 1 malocclusion. The comparison of computerized X-ray cephalometric measurements between the 26 treated children and 26 untreated children was made.The results showed that ANB angle was significantly reduced and horizontal mandibular growth development tended to be normal in the treated group.It was suggested that the bionator headgear combination appliance can restrain the maxillary growth early and promote the forward mandibular growth which contribute the functional jaws correction.展开更多
<span style="font-family:Verdana;">A composite material is made up of two phases, the matrix, and the reinforc</span><span style="font-family:Verdana;">ing materials. The reinforc...<span style="font-family:Verdana;">A composite material is made up of two phases, the matrix, and the reinforc</span><span style="font-family:Verdana;">ing materials. The reinforcing material is embedded over matrix material.</span><span style="font-family:Verdana;"> The reinforcing material works to make the matrix material harder. A fibreglass reinforced composite was developed using E-glass fibre reinforcement and epoxy resin matrix. The composites were produced using the hand lay-up technique with varying fibre percentage of 9%, 13% and 25% by weight percentage of fibreglass mat at orientations of 0<span style="white-space:nowrap;">°</span>, 15<span style="white-space:nowrap;">°</span>, 45<span style="white-space:nowrap;">°</span>, and 90<span style="white-space:nowrap;">°</span> chosen at random. A 13% by weight percentage of chopped mat was also developed for purpose of comparison. The fabricated composites were subjected to tensile test, flexural test, impact test, punch shear test and hardness test to ascertain the appropriate fibre contents and orientation that is optimum for the manufacture of headgears. Analysis of Variance was carried out to determine level </span><span style="font-family:Verdana;">of significance and percentage contribution of the parameters. The results</span><span style="font-family:Verdana;"> show that both fibre orientation and percentage of fibre content reinforcement of have significant influence on the strength and fracture energy of the composite .The fibre orientation has a higher impact on the strength of the composite (79.74%) while the percentage of fibre reinforcement has a lesser impact on the tensile strength of the composite (20.26%).</span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">However, </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">t</span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">he fibre </span><span style="font-family:Verdana;">orientation has a lesser impact on the fracture energy of the composite</span><span style="font-family:Verdana;"> (24.54%) while the percentage of fibre reinforcement has a higher impact on the fracture energy of the composite (75.46%) The result from this study shows that the increase in fibre content increases flexural strength and impact toughness of the fibreglass reinforced composite. A fibre orientation of 90<span style="white-space:nowrap;">°</span> and fibre reinforcement of 25% wt. was determined to be optimally suitable for the manufacture of headgears.</span></span></span></span>展开更多
文摘The purpose of this study was to evaluate skeletal and dental effects of bionator headgear combination appliances on patients in development period with Class Ⅱ, division 1 malocclusion. The comparison of computerized X-ray cephalometric measurements between the 26 treated children and 26 untreated children was made.The results showed that ANB angle was significantly reduced and horizontal mandibular growth development tended to be normal in the treated group.It was suggested that the bionator headgear combination appliance can restrain the maxillary growth early and promote the forward mandibular growth which contribute the functional jaws correction.
文摘<span style="font-family:Verdana;">A composite material is made up of two phases, the matrix, and the reinforc</span><span style="font-family:Verdana;">ing materials. The reinforcing material is embedded over matrix material.</span><span style="font-family:Verdana;"> The reinforcing material works to make the matrix material harder. A fibreglass reinforced composite was developed using E-glass fibre reinforcement and epoxy resin matrix. The composites were produced using the hand lay-up technique with varying fibre percentage of 9%, 13% and 25% by weight percentage of fibreglass mat at orientations of 0<span style="white-space:nowrap;">°</span>, 15<span style="white-space:nowrap;">°</span>, 45<span style="white-space:nowrap;">°</span>, and 90<span style="white-space:nowrap;">°</span> chosen at random. A 13% by weight percentage of chopped mat was also developed for purpose of comparison. The fabricated composites were subjected to tensile test, flexural test, impact test, punch shear test and hardness test to ascertain the appropriate fibre contents and orientation that is optimum for the manufacture of headgears. Analysis of Variance was carried out to determine level </span><span style="font-family:Verdana;">of significance and percentage contribution of the parameters. The results</span><span style="font-family:Verdana;"> show that both fibre orientation and percentage of fibre content reinforcement of have significant influence on the strength and fracture energy of the composite .The fibre orientation has a higher impact on the strength of the composite (79.74%) while the percentage of fibre reinforcement has a lesser impact on the tensile strength of the composite (20.26%).</span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">However, </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">t</span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">he fibre </span><span style="font-family:Verdana;">orientation has a lesser impact on the fracture energy of the composite</span><span style="font-family:Verdana;"> (24.54%) while the percentage of fibre reinforcement has a higher impact on the fracture energy of the composite (75.46%) The result from this study shows that the increase in fibre content increases flexural strength and impact toughness of the fibreglass reinforced composite. A fibre orientation of 90<span style="white-space:nowrap;">°</span> and fibre reinforcement of 25% wt. was determined to be optimally suitable for the manufacture of headgears.</span></span></span></span>