Aim The purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants...Aim The purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants. Methodology Three-dimensional reformatting images were reconstructed by cone beam computed tomography （CBCT） in 34 patients, aged 18 to 35 years, using EZ Implant software. Bone height was measured at 20 sites of interest on the palate. Bone mineral density was measured at the 10 sites with the highest implantation rate, classified using K-mean cluster analysis based on bone height and bone mineral density. Results According to the cluster analysis, 10 sites were classified into three clusters. Significant differences in bone height and bone mineral density were detected between these three clusters （P〈0.05）. The greatest bone height was obtained in cluster 2, followed by cluster 1 and cluster 3. The highest bone mineral density was found in cluster 3, followed by cluster 1 and cluster 2. Conclusion CBCT plays an important role in pre-surgical treatment planning. CBCT is helpful in identifying safe and stable implantation sites for palatal anchorage.展开更多
From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field...From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field-effect transistors （sample A and sample B for three and four times multiple ion-implantation channel region respectively） fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.展开更多
Ion-implantation layers are fabricated by multiple nitrogen ion-implantations （3 times for sample A and 4 times for sample B） into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by u...Ion-implantation layers are fabricated by multiple nitrogen ion-implantations （3 times for sample A and 4 times for sample B） into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by using the Monte Carlo simulator TRIM. The fabrication process and the I-V and C V characteristics of the lateral Ti/4H-SiC Schottky barrier diodes （SBDs） fabricated on these multiple box-like ion-implantation layers are presented in detail. Measurements of the reverse I V characteristics demonstrate a low reverse current, which is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors （MESFETs）, and SiC static induction transistors （SITs）. The parameters of the diodes are extracted from the forward I-V and C-V characteristics. The values of ideality factor n of SBDs for samples A and B are 3.0 and 3.5 respectively, and the values of series resistance Rs are 11.9 and 1.0 kf~ respectively. The values of barrier height φB of Ti/4H-SiC are 0.95 and 0.72 eV obtained by the I-V method and 1.14 and 0.93 eV obtained by the C-V method for samples A and B respectively. The activation rates for the implanted nitrogen ions of samples A and B are 2% and 4% respectively extracted from C V testing results.展开更多
目的:评估一种改良上颌窦底内提升术在口腔种植修复中的临床效果。方法:在2016-12—2018-07期间,于56例上颌后牙缺失患者共83个位点,行穿牙槽嵴顶四周剥离上颌窦底提升术。术前CBCT测量剩余骨高度(residual bone height,RBH),术中植骨,...目的:评估一种改良上颌窦底内提升术在口腔种植修复中的临床效果。方法:在2016-12—2018-07期间,于56例上颌后牙缺失患者共83个位点,行穿牙槽嵴顶四周剥离上颌窦底提升术。术前CBCT测量剩余骨高度(residual bone height,RBH),术中植骨,同期或延期植入种植体。术后即刻拍摄CBCT测量上颌窦底提升高度并观察窦底黏膜完整性。术后至少4个月完成修复,随访观察种植体存留率。结果:3个位点术中因上颌窦黏膜破裂改为侧壁开窗上颌窦底提升术,位点黏膜破裂率为3.61%。其余80个位点术后即刻CBCT显示其中5个位点上颌窦底黏膜破裂,位点黏膜破裂率为6.02%。80个位点中76个位点同期种植,3个位点延期种植,1个位点放弃种植。种植体直径为4.0~5.1 mm,平均(4.73±0.35)mm,长度为8.0~11.5 mm,平均(10.27±0.69)mm。上颌窦底黏膜未破裂的75个位点,术前RBH为0.88~9.27 mm,平均(5.57±1.91)mm;上颌窦底提升高度为4.54~15.14 mm,平均(8.09±1.99)mm。手术至修复时间为4~15个月,平均(7.14±2.06)个月,修复后随访时间为1~20个月,平均(9.36±4.60)个月。2枚种植体于修复前脱落,1枚种植体于修复后脱落,总体种植体存留率96.25%。结论:穿牙槽嵴顶四周剥离,行上颌窦底内提升创伤小,相对安全可靠,短期种植修复效果满意。展开更多
基金supported by Scientific Research Foundation for Returned Scholars of the Ministry of Education of China (No. 245027)the Science and Technology Planning Program of Guangdong Province (No. 2006B35801004)
文摘Aim The purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants. Methodology Three-dimensional reformatting images were reconstructed by cone beam computed tomography （CBCT） in 34 patients, aged 18 to 35 years, using EZ Implant software. Bone height was measured at 20 sites of interest on the palate. Bone mineral density was measured at the 10 sites with the highest implantation rate, classified using K-mean cluster analysis based on bone height and bone mineral density. Results According to the cluster analysis, 10 sites were classified into three clusters. Significant differences in bone height and bone mineral density were detected between these three clusters （P〈0.05）. The greatest bone height was obtained in cluster 2, followed by cluster 1 and cluster 3. The highest bone mineral density was found in cluster 3, followed by cluster 1 and cluster 2. Conclusion CBCT plays an important role in pre-surgical treatment planning. CBCT is helpful in identifying safe and stable implantation sites for palatal anchorage.
文摘From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field-effect transistors （sample A and sample B for three and four times multiple ion-implantation channel region respectively） fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.
文摘Ion-implantation layers are fabricated by multiple nitrogen ion-implantations （3 times for sample A and 4 times for sample B） into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by using the Monte Carlo simulator TRIM. The fabrication process and the I-V and C V characteristics of the lateral Ti/4H-SiC Schottky barrier diodes （SBDs） fabricated on these multiple box-like ion-implantation layers are presented in detail. Measurements of the reverse I V characteristics demonstrate a low reverse current, which is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors （MESFETs）, and SiC static induction transistors （SITs）. The parameters of the diodes are extracted from the forward I-V and C-V characteristics. The values of ideality factor n of SBDs for samples A and B are 3.0 and 3.5 respectively, and the values of series resistance Rs are 11.9 and 1.0 kf~ respectively. The values of barrier height φB of Ti/4H-SiC are 0.95 and 0.72 eV obtained by the I-V method and 1.14 and 0.93 eV obtained by the C-V method for samples A and B respectively. The activation rates for the implanted nitrogen ions of samples A and B are 2% and 4% respectively extracted from C V testing results.
