大鼠冠根部牙髓体内成牙能力比较

目的 比较成年大鼠冠、根部牙髓分别接种于肾被膜下的成牙能力.方法 无菌条件下分离8周龄SD大鼠切牙牙髓,将冠部与根部牙髓锐分离,分别植入大鼠肾被膜下,2周后进行组织学观察.结果 冠部牙髓形成了包含釉质样组织和牙本质-牙髓复合体的牙齿样结构,与正常牙齿相似.而根部牙髓则形成了骨样牙本质结构.结论 成年大鼠牙髓依然具有独立的牙齿发育的能力,冠髓和根髓的成牙能力不尽相同.     

大鼠牙胚细胞团块培养法构建组织工程化牙齿

目的探索采用大鼠牙胚细胞团块培养法在体内构建组织工程化牙齿的可行性。方法体外培养SD仔鼠磨牙牙胚细胞,并将牙胚细胞团置于离心管内孵育48h后植入近交系SD大鼠肾被膜下,2周取材,苏木精-伊红染色,观察移植物中的组织新生情况。结果牙胚细胞团块在肾被膜下生长良好,形成典型的牙髓牙本质复合体样组织和少量釉质样结构,牙本质小管样结构清晰可见,内侧可见长柱状的成牙本质细胞有序排列,牙髓样组织中可见少量血管样结构。结论以牙胚细胞为种子细胞,用团块培养法在大鼠肾被膜下成功地构建出组织工程化牙冠样结构。     

大鼠第一腮弓肾被膜下种植的成牙能力研究

目的:观察E12.5d大鼠第一腮弓肾被膜下的成牙能力。方法:切取E12.5d大鼠第一腮弓(下颌突),种植于肾被膜下,4周后收获种植的组织块,组织学观察种植的第一腮弓的发育情况。结果:种植4周,第一腮弓在肾被膜下继续发育,形成牙齿样结构,包含牙釉质、牙本质、牙髓、成牙本质细胞、上皮根鞘样结构及骨样组织。形成的组织结构与正常发育的牙齿形态结构相似。结论:E12.5d大鼠第一腮弓在肾被膜下可以模拟体内牙齿的发育过程,继续发育形成牙齿样结构。     

出生后牙胚细胞肾被膜移植的成牙能力研究

目的：将出生后牙胚细胞接种于肾被膜下探讨其成牙能力。方法：通过酶消化法获得出生后4d SD仔鼠第一磨牙牙胚细胞，离心后与明胶海绵支架复合植入大鼠肾被膜下，2周后组织学观察移植物中的组织新生情况。结果：细胞与支架复合体形成了包含釉质样组织和牙本质牙髓复合体的牙齿样结构，形成的硬组织与正常牙齿的形态结构与排列方式相似。Masson’s三色法显示绿色矿化基质形成。结论：出生后牙胚细胞仍保留了牙齿发育的遗传信号，体内移植后牙源性上皮细胞与间充质细胞相互作用，能重新排列构建出与正常牙体组织类似的规则排列结构，在适当条件下具有形成组织工程牙齿的潜能。     

大鼠牙胚同种异体异位移植的组织学观察

目的:观察牙胚在同种异体大鼠体内不同部位的发育情况,为进一步组织工程化牙齿的构建探寻合适的体内生长环境。方法:将封闭群SD仔鼠第一磨牙牙胚分别植入SD成年大鼠肾被膜下、肠系膜内、腹膜外间隙、腹腔内和口腔黏膜下,3周取材,HE染色,观察移植牙胚的发育情况。结果:牙胚在肾被膜下和肠系膜内生长良好,釉质和牙髓牙本质复合体继续发育,牙本质小管结构清晰可见;腹膜外间隙和腹腔内牙胚均未进一步发育,且牙髓腔内和移植物周边淋巴细胞浸润明显;口腔黏膜下未回收到移植物。结论:封闭群SD大鼠肾被膜下和肠系膜内环境有利于同种异体牙胚的生长,可为组织工程化牙齿的体内构建提供新的发育环境。     

不同时期大鼠牙齿胚基各部分组织发育能力的研究

目的：比较不同发育时期牙胚各部分异位环境下的发育能力,为牙齿再生重组实验提供参考。方法：分离获取SD大鼠帽状期和钟状末期牙胚,分离成釉上皮与牙乳头间充质,分别将完整牙胚、牙间充质、成釉上皮剪碎后异位移植至同种异体大鼠肾被膜下。4周后取材,对移植物进行组织学观察。结果：帽状期牙胚碎组织块移植物中可见部分不规则的牙齿样结构形成。钟状末期牙问充质碎组织块移植组中既有牙本质牙髓复合体样结构形成,还能观察到大量骨样基质形成。而钟状末期成釉上皮碎组织块移植物生成的组织均为骨样的结构。结论：发育早期牙胚的碎组织较发育末期的牙胚碎组织具有更强的牙齿形成能力,所形成的牙齿结构完整包括釉质、牙本质以及牙髓且顺序正确,提示这个时期牙上皮和间充质之间信号网络所提供的微环境可以更加完善和充分地指导牙齿的发育。     

牙本质磷蛋白和成釉蛋白在组织工程牙胚的表达模式研究

目的：采用大鼠牙胚细胞与胶原蛋白构建组织工程牙齿,通过免疫荧光组织化学分析牙齿特异性蛋白在组织工程牙齿的表达模式。方法：采用出生后4dSD仔鼠磨牙牙胚细胞,培养后将牙胚细胞与胶原蛋白溶液混合构建组织工程牙胚,2W后取材,HE染色观察移植物中的成牙能力,免疫荧光组织化学染色观察牙本质磷蛋白DSP和成釉蛋白AM的表达模式。结果：组织工程牙胚移植后2W可在肾被膜下形成乳白色矿化组织,HE染色可见典型的牙髓牙本质复合体样组织和釉质样结构,免疫荧光组织化学染色观察可见成釉蛋白AM阳性的釉质样结构和牙本质磷蛋白DSP阳性的牙乳头样组织,与正常牙齿组织表达模式一致。结论：采用牙胚细胞可与胶原蛋白进行重新排列形成组织工程牙胚,本实验从组织和蛋白分析上证实了其具有较强的成牙能力,为以后的临床应用提供了理论基础。     

大鼠牙髓干细胞与牙乳头间充质细胞成牙能力的比较研究

目的:探讨采用牙髓干细胞替代牙乳头间充质细胞进行牙齿再生研究的可行性。方法:分别分离培养6周龄SD大鼠切牙牙髓干细胞(DPSCs)和出生1d的SD仔鼠切牙牙乳头间充质细胞(DPMCs),对上述2种细胞的表面标记、增殖能力、体外矿化能力以及向成牙本质细胞分化能力进行比较。结果:DPSCs与DPMCs均具有较强的增殖能力和矿化能力,体外诱导均有成牙本质细胞特异性标记物DSPP基因表达,体内移植后均能够形成牙本质样结构。结论:DPSCs是一种较为理想的牙胚间充质细胞的替代细胞,在适宜的诱导环境中能够替代DPMCs进行牙齿的再生研究。     

重建牙本质-牙髓复合体样结构的实验研究

目的 采用组织工程学的方法重建牙本质-牙髓复合体样结构。方法以大鼠牙髓干细胞为种子细胞，将羟基磷灰石-磷酸三钙（HA-TCP）复合支架材料接种至裸鼠背部皮下，8周后取材进行组织学及免疫组织化学检测。结果移植物组织学切片可见支架材料孔隙内有3层组织结构，由外向内分别为矿化牙本质、前期牙本质及牙髓组织，其中牙本质小管明显，牙髓组织外层细胞密集，部分出现极化，呈现出成牙本质细胞样细胞特征。免疫组织化学染色证实人牙本质特异性蛋白、DMP1在前期牙本质区及成牙本质细胞样细胞为阳性表达。结论采用牙髓干细胞为种子细胞、HA-TCP为支架材料可成功构建牙本质-牙髓复合体样结构，为进一步进行牙齿组织工程再造奠定基础。     

猪牙源性间充质与胶原类材料复合移植的实验研究

目的：探讨经体外培养的出生后的猪牙源性间充质细胞成牙能力。方法：将体外培养第4代的猪牙胚细胞接种到胶原凝胶基质中，体外培养3d后进行裸鼠体内移植，6W后取材观察。结果：猪牙胚细胞原代培养过程中可见上皮样细胞与成纤维样细胞混杂存在，传代3次后上皮样细胞消失。细胞胶原基质复合物取材结果显示细胞聚集的区域可见牙本质-牙髓复合体样结构。结论：经体外传代培养后未经体外诱导的牙胚细胞接种到胶原凝胶基质所构建的组织工程牙齿有牙本质-牙髓复合体样结构形成，说明牙胚细胞经体外培养后其所获得的发育信息仍可保持，是研究牙齿发育构建模型及组织工程牙齿的理想的种子细胞。     

大鼠切牙颈环上皮细胞的培养

目的：培养大鼠切牙颈环上皮细胞。方法：选择出生后（postnatal,PN）8d的SD大鼠,分离下颌切牙牙胚,切取切牙颈环结构,酶消化法细胞培养。通过差别消化法初步纯化颈环上皮细胞,抗角蛋白免疫化学染色初步鉴定颈环上皮细胞。结果：原代培养细胞为上皮和间充质混杂的细胞,经初步纯化获得铺路石样排列的,角蛋白阳性的颈环上皮细胞团。结论：实验成功培养了大鼠切牙颈环上皮细胞。     

鼠尾胶原在培养鼠下切牙颈环上皮细胞中的应用

目的: 建立用自制鼠尾胶原为贴附底物的大鼠颈环上皮细胞的体外培养模式.方法: 制作鼠尾胶原,观察用自制的鼠尾胶原培养出大鼠颈环上皮细胞的效果,并对纯化的上皮细胞进行免疫组织化学染色鉴定.结果: 自制的鼠尾胶原能正常地培养出大鼠颈环上皮细胞,呈多角形,克隆状生长,β1整合素和角蛋白免疫组织化学染色阳性.结论: 鼠尾胶原可作大鼠颈环上皮细胞的体外培养贴附底物,为今后研究牙齿发育机制提供简便的方法和途径.     

Changes in Gingival Recession Related to Orthodontic Treatment of Traumatic Deep Bites in Adults

INTRODUCTION: It was the aim of this investigation to establish whether orthodontic treatment of traumatic deep bites can restore trauma-related gingival recessions in adults. SUBJECTS AND METHODS: Forty-one incisor sites with trauma-related recession (group Tr) and 54 trauma-free sites (group NonTr) were diagnosed in the upper palatal or lower buccal regions in twelve adult patients (mean age 38.3 +/- 8.1 years). The 48 antagonistic sites on the buccal aspects of the upper incisors (Ubuc) and 47 sites on the lingual aspects of the lower incisors (L-ling) were also evaluated. Changes in clinical crown lengths achieved during treatment were measured on dental casts, and length changes in recessions were measured on screen projections of magnified intraoral photographs. RESULTS: The clinical crown lengths (mean: -1.13 +/- 0.97 mm) and recession depths (mean: -2.05 +/- 0.93 mm) decreased significantly (p < 0.001) in the trauma group (Tr). We also observed significant shortening (p < 0.05) of clinical crown lengths in the buccal sites of upper incisors (U-buc) (mean: -0.16 +/- 0.46 mm). All other changes were insignificant. CONCLUSIONS: Orthodontic treatment of traumatic deep bites involving removal of gingival trauma and intrusion of incisor teeth shows great potential in reducing the length of clinical crowns and depth of gingival recessions. In trauma-free buccal sites of upper incisors, intrusion therapy may also improve the gingival marginal contour.     

Effect of Incisor Angulation on Overjet and Overbite in Class II Camouflage Treatment. A typodont study

OBJECTIVES: To determine the amount of variation in overjet and overbite that may result from changes in upper and lower incisor angulations following upper first premolar extraction treatment in Class II malocclusions. MATERIALS AND METHODS: Typodonts were set up to simulate a skeletal Class II occlusion treated with upper first premolar extractions. The upper incisor angulation was altered through a range from 100 degrees to 120 degrees to the palatal plane by 2 degrees increments. The overjet and overbite were measured with every 2 degrees of upper incisor angulation change. A regression analysis was performed on the experimental data, and the regression coefficients, slope, and intercept were estimated. RESULTS: Excessive proclination of the lower incisors will result in an abnormal overjet and overbite relationship for any magnitude of upper incisor angulation. A normal lower incisor angulation facilitates the attainment of an optimal occlusion. Excessive palatal root torque of the upper incisors will result in an increase in overjet and a consequent decrease in overbite. If the upper incisors are excessively retroclined, an edge-to-edge incisor relationship will result. CONCLUSION: Class II camouflage treatment with upper first premolar extractions requires correctly angulated incisors to achieve optimal buccal segment interdigitation and incisor relationship. Labial root torque and interproximal reduction of the lower anterior teeth should be considered when the lower incisors are excessively proclined.     

A method of calculating the speed of movement of ameloblasts during rat incisor amelogenesis.

Ameloblast migration rates during secretion of enamel in rat incisors were calculated from measurements of (1) certain angular and linear parameters pertaining to the prism pattern, (2) the length of the zones of enamel secretion, (3) the impeded eruption rate of rat incisors, and (4) the diameters of the circles of which the rat incisors are parts. It is assumed that the ameloblasts move along the path of the prisms, that the incisors of adult rats erupt along the are of a stationary circle, and that the length of the zones of enamel secretion does not change with age. From data in the literature, the transverse component of ameloblast migration was calculated to be 9.9 /gmm/day in the upper incisor and 13.4μm/day in the lower. If adjacent rows of ameloblasts move in opposite directions, each ameloblast will in 1 day slide past five ameloblasts of the adjacent row in the upper incisor and past seven ameloblasts in the lower incisor. The results obtained for the component of ameloblast migration from the dentine surface were 9.0μm/day in the upper incisor and 12.3 μm/day in the lower, which are below the 16 /gmm/day enamel apposition rate of other workers. Due to the gingival inclination of enamel prisms, the ameloblasts move gingivally faster than the tooth erupts. This movement is faster during secretion of outer enamel than that of inner enamel. The increased inclination of prisms in the outer enamel zone may be effected by an increase in the gingivo-basal diameter of ameloblasts as they enter the zone of outer enamel secretion.     

18例12～20岁严重骨性Ⅲ类牙颌畸形非手术正畸治疗的初步研究

目的　旨在对非手术矫治成功的 12～ 2 0岁严重骨性Ⅲ类牙颌畸形病例矫治前后的X线侧位片作头影测量分析 ,进行牙及软组织侧貌的评价 ,为临床矫治提供有价值的依据。方法　 18例恒牙期与成人严重骨性Ⅲ类牙颌畸形病例 ,男 5例 ,女 13例。年龄 12～ 2 0 (14 6± 2 5 )岁。 12例采用Tip Edge差动直丝弓矫正技术 ,6例采用Begg细丝弓矫正技术。平均治疗时间为 (2 5±0 8)年。病例选择标准 :①近中或超完全近中磨牙关系 ,后者指上颌第一恒磨牙近中颊尖咬合于下颌第二恒磨牙颊沟 ;②下颌不能后退 ;③Ⅲ类骨型 (ANB <- 1 5°) ;④多为高角病例 ,SN MP平均值为(34 9± 5 9)°,有 4例合并前牙开畸形 ;⑤侧貌呈凹面型 ;⑥已经其他正畸医师诊断为手术适应证 ,但患者及家属拒绝接受手术治疗。治疗前后拍摄头影测量片 ,用常规头影测量分析方法进行分析。计算头影测量各指标的均值与标准差 ,采用配对t检验分析治疗前后各指标的统计学差异。结果　治疗结束后上颌前牙发生明显的唇向倾斜移动 ,下颌前牙发生明显的舌向倾斜移动 ,建立正常覆覆盖关系。U1 SN角平均增加了 5 9° (P <0 .0 0 1) ,L1 MP角平均减少了 6 6°(P <0 0 0 1)。上下唇至Sn Pg审美线的差距 ,由矫治前的负均值变为矫治后的正均值且差异有     

36例下切牙先天缺失正畸治疗的临床体会

目的探讨下切牙先天缺失的矫治设计。方法以伴有下切牙先天缺失的36例错畸形患者为研究对象，对下切牙缺失的部位、数目、错类型、矫治方法进行分析，并对缺失1颗下中切牙、拔除上颌2颗第一前磨牙和下颌1颗非缺牙侧第一前磨牙的病例及缺失2颗下中切牙、拔除上颌2颗第一前磨牙的病例的Bolton指数分析进行统计学检验。结果36例患者正畸治疗后均取得了较好的疗效。两组拔牙病例之间的Bolton指数全牙比无统计学差异（P>0.05），而前牙比和前牙不调量有统计学差异（P<0.01）。结论先天缺1颗下中切牙上下颌均需拔牙者，在下颌非缺牙侧选择拔1颗前磨牙比拔1颗中切牙对Bolton指数影响要小     

The effects of torque control spurs in twin-block appliances

The study compared the effects of torque control spurs on upper incisor retroclination and extrusion with two designs of a twin-block functional appliance in Class II/1 cases. The two designs were also compared with respect to anchorage loss in the lower arch and for patient compliance rates. Consecutively started cases were chosen - 90 patients with a design incorporating a labial bow (CTB group) and 110 with upper incisor 'torquing' spurs (STB group) and used to calculate failure rates. Thirty consecutive patients with satisfactory records from each group were analysed cephalometrically. The STB group experienced substantially less upper incisor retroclination, reduced upper incisor extrusion and slightly more favourable mandibular growth. The labial movement of lower incisors and the patient compliance were not significantly different in the two groups. Overall, 82.5% of patients fully reduced their overjet with 9% failing to reduce the overjet below 6 mm.Fig. 1f     

老年人前后牙牙髓感觉功能昼夜节律性的比较研究

目的：比较老年人前、后牙牙髓感觉昼夜节律的差异，以指导选择老年人缺失牙修复最佳就医时间。方法：在24h内7个等距间隔时间点，测定20名受试老年人上颌中切牙（切牙组）和下颌第一恒磨牙（磨牙组）牙髓活力的阈值，运用Halberg余弦法分析切牙组和磨牙组牙髓感觉功能的生物节律，并比较二者的差异。结果：两者整体变化趋势一致，感觉阈值的最高峰和最低谷分别出现在0：00与12：00。磨牙牙髓感觉闽值的振幅、振幅比中值大干切牙，整体水平和中值略高于切牙。结论：老年人切牙与磨牙的牙髓感觉功能均具有昼夜节律性，感觉最迟钝和最敏感的时间分别在0：00与12：00。     

The retraction of upper incisors with the PG retraction system

The aim of this study was to evaluate the effect on the dentoalveolar structures of the application of PG springs for retraction of upper incisors and to compare the outcome with the effect of a closed coil spring retraction system. Thirty-six subjects with Angle Class I or Class II malocclusions were selected for the study. Each subject had the two upper first premolars extracted and presented a symmetrical extraction space of at least 3 mm distal to the lateral incisors after canine retraction. The subjects were divided into two groups, the PG group with 17 subjects and the coil group with 19 patients. One group had the incisors retracted by PG universal retraction springs, whereas in the other a closed coil spring system was used. The average chronological ages were 18 years 4 months for the PG group, and 18 years 7 months for the coil group. In both groups the springs were activated to produce an initial force of 150 g per side. To examine the type of movement of the anterior and posterior teeth, and the time and rate of space closure, 20 parameters were measured and evaluated statistically with Wilcoxon and Mann-Whitney U-tests. In both groups the incisor retraction was accompanied by mesial movement of the buccal segments. Distal movement of the root apex of the incisors was observed in both groups, although more pronounced in the PG group (P < 0.01). A significant incisor intrusion resulting in a decrease in overbite was found in the PG group, whereas the deep bite increased significantly in the coil spring group. The PG spring produced a three-dimensional control in the movement of the upper incisors, so that application of additional intrusive mechanics after completion of the incisor retraction became unnecessary.