We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to be...We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.展开更多
A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM).Due to the unbalanced back electro-motive force (EMF) and impedance produced,unbal...A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM).Due to the unbalanced back electro-motive force (EMF) and impedance produced,unbalanced current is generated.The circulating current,which is caused by a decrease in the thrust,is generated by the unbalanced current.The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE),and compared with the basic model through finite element analysis (FEA).As a result,the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase.Also,this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.展开更多
The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar a...The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar are analysed. The results are as follows: The eruption rate of first molar in 7968 cases 4-6 yrs old children is 22.13%. The mean number of molar erupted is 0.55+1.17. Both are in very signiflicant sexual difference. The eruption in girls is earlier than that in boys. The eruption rates are 1.01% in 4 yrs old group and 59.00% in 6 yrs old group. In the per centage of the molar erupted, (?) is 66.26% with symmetrical rate 69.31%, 6 is 33.74% with symmetrical rate 33.24%. The incidence rate of caries in 1763 cases 4-6 yrs old children with first molar erupted is 1.76% with dft 0.02±0.15. The dft in cases of caries is 1.26±0.63. There are two molars with caries of Degree IV in 5 yrs old group. The eruption and caries of the first molar in childhood are analysed. The importance of prevention dnd treatment of first permanent molar in childhood is indicated.展开更多
The aim of this study is to assess if there is a significant difference between crown to root ratio of male and female permanent teeth in Chinese people in Shanghai.Methods: For this purpose one thousand four hundred ...The aim of this study is to assess if there is a significant difference between crown to root ratio of male and female permanent teeth in Chinese people in Shanghai.Methods: For this purpose one thousand four hundred (700,male and 700,female) extracted teeth were collected between age 25-35 and the crown length (CL) and root length (RL) of permanent teeth were measured by a precise caliper.Statistical analyses were performed with the SPSS 17 software by Student's t-test method.Results: The mean crown length of permanent teeth of male was found to be larger than that of female except for maxillary central incisor and the mean root length of male was found to be comparatively larger than that of female.Conclusion: There was a significant difference in root to crown ratio (RL/CL) between male maxillary teeth and mandibular teeth and female ones.The RL/CL ratio of male tends to be larger than those of female in Shanghai population.展开更多
In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolatio...In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolation of the fault-tolerant generator are analyzed briefly.Secondly,the auxiliary teeth structure is optimized to improve fault-tolerant capability.Then,the PM generators with different stator structures are compared to evaluate the proposed auxiliary teeth structure.Four critical generator parameters are investigated,i.e.back-electromotive forces,short-circuit currents,stator magneto motive force(MMF)harmonics,and torque performances.The results show that the proposed structure has better fault-tolerant capability than the conventional two-layer windings.Moreover,the stator MMF harmonics can be suppressed.Furthermore,the cogging torque and torque ripple can be suppressed by adopting the proposed structure.Finally,the simulated results are given to validate the theoretical analysis.展开更多
目的:观察不同年龄患者牙髓切断术的临床疗效,探讨牙髓钙化发生的情况和特点。方法:选择2019年10月到2022年8月就诊于北京大学口腔医院综合科龋源性露髓的成年恒前磨牙、恒磨牙行牙髓切断术的患者共77例,使用iRoot BP Plus生物陶瓷类材...目的:观察不同年龄患者牙髓切断术的临床疗效,探讨牙髓钙化发生的情况和特点。方法:选择2019年10月到2022年8月就诊于北京大学口腔医院综合科龋源性露髓的成年恒前磨牙、恒磨牙行牙髓切断术的患者共77例,使用iRoot BP Plus生物陶瓷类材料作为盖髓剂,一次法完成牙髓切断术。将患者按年龄分为3组,青少年组(11~20岁)25例,平均年龄(15.88±2.19)岁;中年组(21~50岁)27例,平均年龄(34.59±8.67)岁;老年组(51~83岁)25例,平均年龄(63.84±7.40)岁。术后1年复查,评价临床疗效,记录钙化桥形成、钙化桥厚度,以及牙髓钙化指数(pulp calcification index,PCI)。结果:3组患者在性别、牙列及牙位分布上差异均无统计学意义(P>0.05)。术后1年随访率为85.71%(66/77),其中青少年组随访率为88.00%(22/25),中年组随访率为85.19%(23/27),老年组随访率为84.00%(21/25)。3组病例1年复查临床成功率分别为95.45%(21/22)、91.30%(21/23)、95.24%(20/21),差异无统计学意义(P>0.05)。临床成功病例中,钙化桥出现率青少年组12例(57.14%,12/21),中年组8例(38.10%,8/21),老年组3例(15.00%,3/20),差异有统计学意义(χ^(2)=7.810,P=0.020<0.05)。3组间钙化桥厚度比较差异有统计学意义(F=4.434,P=0.020<0.05)。钙化桥厚度与年龄呈负相关(r=-0.516,P<0.05)。3组间PCI变化(ΔPCI)分别为0.67±0.58、0.43±0.51、0.25±0.52,差异有统计学意义(F=3.404,P=0.040<0.05)。结论:老年患者龋源性露髓牙髓切断术同样能够获得较高的成功率;牙髓切断术后钙化桥的发生率以及牙髓钙化的加速程度与年龄相关;青少年组更易形成钙化桥,同时也出现更明显的根管钙化加速现象。展开更多
目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月...目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月因恒前牙复杂冠折就诊于北京大学口腔医院急诊科,行以生物活性陶瓷iRoot BP Plus^(■)为盖髓剂的牙髓切断术患者。根据患者术前根尖片和初诊病历显示为年轻恒牙者,纳入97颗年轻恒牙进行研究。收集患者初诊及复查时的临床及影像学检查资料,临床检查包括根尖孔形成情况、松动度、牙冠颜色、牙髓活力测试(冷测)、有无脓肿和瘘管,影像学检查包括根周膜连续性、根尖周低密度影像、复诊时盖髓剂下方牙本质桥形成情况、髓腔及根管钙化情况,并对上述结果进行分析。结果:最终纳入有复诊记录的64例患者共75颗患牙,其中男性37例(57.8%),女性27例(42.2%),就诊时平均年龄为9.1岁,平均随访时长19.3个月。采用iRoot BP Plus^(■)盖髓的牙髓切断术后6个月成功率为96.0%,术后1年成功率为94.7%。术后复查2年以上者共23例,累计失败6例。成功率在患牙就诊时距外伤的时间是否超过24 h组中(P=0.61)以及是否松动组中(P=0.28)的差异无统计学意义。结论:对无移位性损伤的年轻恒牙复杂冠折患牙,采用iRoot BP Plus^(■)盖髓的牙髓切断术1年成功率很高,该术式具备广泛推广价值。展开更多
文摘We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.
基金supported by the Second Stage of Brain Korea 21 Projects and Changwon National University in 2009-2010
文摘A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM).Due to the unbalanced back electro-motive force (EMF) and impedance produced,unbalanced current is generated.The circulating current,which is caused by a decrease in the thrust,is generated by the unbalanced current.The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE),and compared with the basic model through finite element analysis (FEA).As a result,the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase.Also,this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.
文摘The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar are analysed. The results are as follows: The eruption rate of first molar in 7968 cases 4-6 yrs old children is 22.13%. The mean number of molar erupted is 0.55+1.17. Both are in very signiflicant sexual difference. The eruption in girls is earlier than that in boys. The eruption rates are 1.01% in 4 yrs old group and 59.00% in 6 yrs old group. In the per centage of the molar erupted, (?) is 66.26% with symmetrical rate 69.31%, 6 is 33.74% with symmetrical rate 33.24%. The incidence rate of caries in 1763 cases 4-6 yrs old children with first molar erupted is 1.76% with dft 0.02±0.15. The dft in cases of caries is 1.26±0.63. There are two molars with caries of Degree IV in 5 yrs old group. The eruption and caries of the first molar in childhood are analysed. The importance of prevention dnd treatment of first permanent molar in childhood is indicated.
文摘The aim of this study is to assess if there is a significant difference between crown to root ratio of male and female permanent teeth in Chinese people in Shanghai.Methods: For this purpose one thousand four hundred (700,male and 700,female) extracted teeth were collected between age 25-35 and the crown length (CL) and root length (RL) of permanent teeth were measured by a precise caliper.Statistical analyses were performed with the SPSS 17 software by Student's t-test method.Results: The mean crown length of permanent teeth of male was found to be larger than that of female except for maxillary central incisor and the mean root length of male was found to be comparatively larger than that of female.Conclusion: There was a significant difference in root to crown ratio (RL/CL) between male maxillary teeth and mandibular teeth and female ones.The RL/CL ratio of male tends to be larger than those of female in Shanghai population.
基金supported by the Key Research and Development Program of Jiangsu Province(BE2018107)by the Natural Science Foundation of Jiangsu Province(BK20191225).
文摘In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolation of the fault-tolerant generator are analyzed briefly.Secondly,the auxiliary teeth structure is optimized to improve fault-tolerant capability.Then,the PM generators with different stator structures are compared to evaluate the proposed auxiliary teeth structure.Four critical generator parameters are investigated,i.e.back-electromotive forces,short-circuit currents,stator magneto motive force(MMF)harmonics,and torque performances.The results show that the proposed structure has better fault-tolerant capability than the conventional two-layer windings.Moreover,the stator MMF harmonics can be suppressed.Furthermore,the cogging torque and torque ripple can be suppressed by adopting the proposed structure.Finally,the simulated results are given to validate the theoretical analysis.
文摘目的:观察不同年龄患者牙髓切断术的临床疗效,探讨牙髓钙化发生的情况和特点。方法:选择2019年10月到2022年8月就诊于北京大学口腔医院综合科龋源性露髓的成年恒前磨牙、恒磨牙行牙髓切断术的患者共77例,使用iRoot BP Plus生物陶瓷类材料作为盖髓剂,一次法完成牙髓切断术。将患者按年龄分为3组,青少年组(11~20岁)25例,平均年龄(15.88±2.19)岁;中年组(21~50岁)27例,平均年龄(34.59±8.67)岁;老年组(51~83岁)25例,平均年龄(63.84±7.40)岁。术后1年复查,评价临床疗效,记录钙化桥形成、钙化桥厚度,以及牙髓钙化指数(pulp calcification index,PCI)。结果:3组患者在性别、牙列及牙位分布上差异均无统计学意义(P>0.05)。术后1年随访率为85.71%(66/77),其中青少年组随访率为88.00%(22/25),中年组随访率为85.19%(23/27),老年组随访率为84.00%(21/25)。3组病例1年复查临床成功率分别为95.45%(21/22)、91.30%(21/23)、95.24%(20/21),差异无统计学意义(P>0.05)。临床成功病例中,钙化桥出现率青少年组12例(57.14%,12/21),中年组8例(38.10%,8/21),老年组3例(15.00%,3/20),差异有统计学意义(χ^(2)=7.810,P=0.020<0.05)。3组间钙化桥厚度比较差异有统计学意义(F=4.434,P=0.020<0.05)。钙化桥厚度与年龄呈负相关(r=-0.516,P<0.05)。3组间PCI变化(ΔPCI)分别为0.67±0.58、0.43±0.51、0.25±0.52,差异有统计学意义(F=3.404,P=0.040<0.05)。结论:老年患者龋源性露髓牙髓切断术同样能够获得较高的成功率;牙髓切断术后钙化桥的发生率以及牙髓钙化的加速程度与年龄相关;青少年组更易形成钙化桥,同时也出现更明显的根管钙化加速现象。
文摘目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月因恒前牙复杂冠折就诊于北京大学口腔医院急诊科,行以生物活性陶瓷iRoot BP Plus^(■)为盖髓剂的牙髓切断术患者。根据患者术前根尖片和初诊病历显示为年轻恒牙者,纳入97颗年轻恒牙进行研究。收集患者初诊及复查时的临床及影像学检查资料,临床检查包括根尖孔形成情况、松动度、牙冠颜色、牙髓活力测试(冷测)、有无脓肿和瘘管,影像学检查包括根周膜连续性、根尖周低密度影像、复诊时盖髓剂下方牙本质桥形成情况、髓腔及根管钙化情况,并对上述结果进行分析。结果:最终纳入有复诊记录的64例患者共75颗患牙,其中男性37例(57.8%),女性27例(42.2%),就诊时平均年龄为9.1岁,平均随访时长19.3个月。采用iRoot BP Plus^(■)盖髓的牙髓切断术后6个月成功率为96.0%,术后1年成功率为94.7%。术后复查2年以上者共23例,累计失败6例。成功率在患牙就诊时距外伤的时间是否超过24 h组中(P=0.61)以及是否松动组中(P=0.28)的差异无统计学意义。结论:对无移位性损伤的年轻恒牙复杂冠折患牙,采用iRoot BP Plus^(■)盖髓的牙髓切断术1年成功率很高,该术式具备广泛推广价值。
