BACKGROUNDMandibular fractures constitute about 80.79% of maxillofacial injuries inAlexandria University, either as isolated mandibular fractures or as a part ofpanfacial fractures. The combination of symphyseal and p...BACKGROUNDMandibular fractures constitute about 80.79% of maxillofacial injuries inAlexandria University, either as isolated mandibular fractures or as a part ofpanfacial fractures. The combination of symphyseal and parasymphyseal fracturesrepresent 47.09% of the total mandibular fractures.AIMTo compare the effectiveness of lag screws vs double Y-shaped miniplates in thefixation of anterior mandibular fractures.METHODSThis study is a prospective randomized controlled clinical trial, performed onsixteen patients with anterior mandibular fractures. Patients were divided equallyinto two groups, each consisting of eight patients. Group 1: Underwent openreduction and internal fixation using two lag screws. Group 2: Underwent openreduction and internal fixation using double Y-shaped plates. The followingparameters were assessed: operating time in minutes, pain using a visual analogscale, edema, surgical wound healing for signs and symptoms of infection,occlusion status and stability, maximal mouth opening, and sensory nervefunction. Cone beam computed tomography was performed at 3 and 6 mo tomeasure bone density and assess the progression of fracture healing.RESULTSThe study included 13 males (81.3%) and 3 females (18.8%) aged 26 to 45 years(mean age was 35.69 ± 6.01 years). The cause of trauma was road traffic accidentsin 10 patients (62.5%), interpersonal violence in 3 patients (18.8%) and othercauses in 3 patients (18.8%). The fractures comprised 10 parasymphyseal fractures(62.5%) and 6 symphyseal fractures (37.5%). The values of all parameters were comparable in both groups with no statistically significant difference except forthe mean bone density at 3 mo postoperatively which was 946.38 ± 66.29 in group 1 and 830.36 ± 95.53 in group 2 (P = 0.015).CONCLUSIONBoth lag screws and double Y-shaped miniplates provide favorable means offixation for mandibular fractures in the anterior region. Fractures fixed with lagscrews show greater mean bone density at 3 mo post-operation, indicative ofhigher primary stability and faster early bone healing. Further studies with largersample sizes are required to verify these conclusions.展开更多
The investigation on the superplastic bugling capability of 1.5?mm mill annealed Ti 6Al 4V buttcover plate by means of manual gas tungsten arc welding (M GTAW) and fusion type plasma arc welding (F PAW) have been eval...The investigation on the superplastic bugling capability of 1.5?mm mill annealed Ti 6Al 4V buttcover plate by means of manual gas tungsten arc welding (M GTAW) and fusion type plasma arc welding (F PAW) have been evaluated respectively. The result shows that untreated Ti 6Al 4V buttcover plate by M GTAW exhibits no superplasticity, while the same untreated plate by F PAW, shows good superplastic ability because of extremely fine acicular martensite microstructure of weld metal. To the buttcover plate by M GTAW, the microstructure of weld metal changed into streaky α structure which exhibits good superplasticity from the original β structure under the condition of the constant temperature of 940?℃ with the deformation degree of 45%, and changed into the fine equiaxed grain which possesses excellent superplastic ability under the condition of the constant temperature of 800?℃ with the deformation degree of 40%.展开更多
A multi-step isothermal forging and subsequent multipass rolling was used to produce one kind of two phase titanium alloy plate with thickness of 2.2 mm. Tensile properties at ambient temperature and at two kinds of h...A multi-step isothermal forging and subsequent multipass rolling was used to produce one kind of two phase titanium alloy plate with thickness of 2.2 mm. Tensile properties at ambient temperature and at two kinds of high temperatures were investigated for the plate with submicrocrystalline (SMC) structure in present work. Microstructures and fractographies of the alloy plate before and after tensile tests were also observed by scanning electron microscope. The results indicated that the alloy possesses favorite integrated tensile properties at ambient temperature, the average UTS and elongation for the longitudinal sample is 1070 MPa and 20%, while which for the transverse sample is 1103 MPa and 15%. The tensile elongation of the alloy plate is as high as 1078% at 780°C with a primary strain rate of 1.7 × 10<sup>-3</sup> s<sup>-1</sup>. The microstructure is fine for the alloy plate solutioned at 700°C for 1 h, AC, and the grain size after tensile test is 2 μm and 3 μm for the longitudinal and transverse plates. Fractography for the as-annealed plate is composed of a large number of dimples and voids after tensile test at ambient temperature.展开更多
文摘BACKGROUNDMandibular fractures constitute about 80.79% of maxillofacial injuries inAlexandria University, either as isolated mandibular fractures or as a part ofpanfacial fractures. The combination of symphyseal and parasymphyseal fracturesrepresent 47.09% of the total mandibular fractures.AIMTo compare the effectiveness of lag screws vs double Y-shaped miniplates in thefixation of anterior mandibular fractures.METHODSThis study is a prospective randomized controlled clinical trial, performed onsixteen patients with anterior mandibular fractures. Patients were divided equallyinto two groups, each consisting of eight patients. Group 1: Underwent openreduction and internal fixation using two lag screws. Group 2: Underwent openreduction and internal fixation using double Y-shaped plates. The followingparameters were assessed: operating time in minutes, pain using a visual analogscale, edema, surgical wound healing for signs and symptoms of infection,occlusion status and stability, maximal mouth opening, and sensory nervefunction. Cone beam computed tomography was performed at 3 and 6 mo tomeasure bone density and assess the progression of fracture healing.RESULTSThe study included 13 males (81.3%) and 3 females (18.8%) aged 26 to 45 years(mean age was 35.69 ± 6.01 years). The cause of trauma was road traffic accidentsin 10 patients (62.5%), interpersonal violence in 3 patients (18.8%) and othercauses in 3 patients (18.8%). The fractures comprised 10 parasymphyseal fractures(62.5%) and 6 symphyseal fractures (37.5%). The values of all parameters were comparable in both groups with no statistically significant difference except forthe mean bone density at 3 mo postoperatively which was 946.38 ± 66.29 in group 1 and 830.36 ± 95.53 in group 2 (P = 0.015).CONCLUSIONBoth lag screws and double Y-shaped miniplates provide favorable means offixation for mandibular fractures in the anterior region. Fractures fixed with lagscrews show greater mean bone density at 3 mo post-operation, indicative ofhigher primary stability and faster early bone healing. Further studies with largersample sizes are required to verify these conclusions.
文摘The investigation on the superplastic bugling capability of 1.5?mm mill annealed Ti 6Al 4V buttcover plate by means of manual gas tungsten arc welding (M GTAW) and fusion type plasma arc welding (F PAW) have been evaluated respectively. The result shows that untreated Ti 6Al 4V buttcover plate by M GTAW exhibits no superplasticity, while the same untreated plate by F PAW, shows good superplastic ability because of extremely fine acicular martensite microstructure of weld metal. To the buttcover plate by M GTAW, the microstructure of weld metal changed into streaky α structure which exhibits good superplasticity from the original β structure under the condition of the constant temperature of 940?℃ with the deformation degree of 45%, and changed into the fine equiaxed grain which possesses excellent superplastic ability under the condition of the constant temperature of 800?℃ with the deformation degree of 40%.
文摘A multi-step isothermal forging and subsequent multipass rolling was used to produce one kind of two phase titanium alloy plate with thickness of 2.2 mm. Tensile properties at ambient temperature and at two kinds of high temperatures were investigated for the plate with submicrocrystalline (SMC) structure in present work. Microstructures and fractographies of the alloy plate before and after tensile tests were also observed by scanning electron microscope. The results indicated that the alloy possesses favorite integrated tensile properties at ambient temperature, the average UTS and elongation for the longitudinal sample is 1070 MPa and 20%, while which for the transverse sample is 1103 MPa and 15%. The tensile elongation of the alloy plate is as high as 1078% at 780°C with a primary strain rate of 1.7 × 10<sup>-3</sup> s<sup>-1</sup>. The microstructure is fine for the alloy plate solutioned at 700°C for 1 h, AC, and the grain size after tensile test is 2 μm and 3 μm for the longitudinal and transverse plates. Fractography for the as-annealed plate is composed of a large number of dimples and voids after tensile test at ambient temperature.
