XRD Characterization of Crystallinity of Human Tooth Enamel under Influence of Mechanical Grinding

Crystallinity refers to the degree of structural order in a solid and has a big influence on hardness, density, transparency and diffusion. Even within materials that are crystalline completely, the degree of structural perfection can vary, reflecting size and elastic strain of many independent crystalline regions (grains or crystallites) of which these materials are composed. In this work it was attempted to reduce the crystallinity of human enamel using a technique of mechanical grinding (MG) with an ultra-compact FRITSCH Mini-Mill PULVERISETTE 23 machine. Variation in the crystallinity through the MG was monitored by X-ray diffraction (XRD) by broadening of the diffraction peak and examined using the Williamson-Hall plot method. Crystallites in human enamel are regularly arranged and oriented (in the [001] direction) perpendicularly to the interface of enameldentin junction. The results showed an anisotropic feature in crystallinity. Reduction of the crystallinity along the a-axis is due to the crystal strain rather than to the refinement of crystal, and vice versa along the c-axis. After 230 h of the MG, the length of crystallites decreased from 100 nm to 30 nm and width from 40 nm to 37 nm approximately.

PiggyBac transposon-mediated gene delivery efficiently generates stable transfectants derived from cultured primary human deciduous tooth dental pulp cells(HDDPCs) and HDDPC-derived iPS cells

The ability of human deciduous tooth dental pulp cells（HDDPCs） to differentiate into odontoblasts that generate mineralized tissue holds immense potential for therapeutic use in the field of tooth regenerative medicine. Realization of this potential depends on efficient and optimized protocols for the genetic manipulation of HDDPCs. In this study, we demonstrate the use of a Piggy Bac（PB）-based gene transfer system as a method for introducing nonviral transposon DNA into HDDPCs and HDDPC-derived inducible pluripotent stem cells. The transfection efficiency of the PB-based system was significantly greater than previously reported for electroporation-based transfection of plasmid DNA. Using the neomycin resistance gene as a selection marker, HDDPCs were stably transfected at a rate nearly 40-fold higher than that achieved using conventional methods. Using this system, it was also possible to introduce two constructs simultaneously into a single cell. The resulting stable transfectants, expressing td Tomato and enhanced green fluorescent protein, exhibited both red and green fluorescence. The established cell line did not lose the acquired phenotype over three months of culture. Based on our results, we concluded that PB is superior to currently available methods for introducing plasmid DNA into HDDPCs. There may be significant challenges in the direct clinical application of this method for human dental tissue engineering due to safety risks and ethical concerns. However, the high level of transfection achieved with PB may have significant advantages in basic scientific research for dental tissue engineering applications, such as functional studies of genes and proteins. Furthermore, it is a useful tool for the isolation of genetically engineered HDDPC-derived stem cells for studies in tooth regenerative medicine.

Orthodontic tooth separation activates the hypothalamic area in the human brain

OBJECTIVES： An animal experiment clarified that insertion of an orthodontic apparatus activated the trigeminal neurons of the medulla oblongata. Orthodontic tooth movement is known to be associated with the sympathetic nervous system and controlled by the nucleus of the hypothalamus. However, the transmission of both has not been demonstrated in humans. The purpose of this study were to examine the activated cerebral areas using brain functional magnetic resonance imaging（MRI）, when orthodontic tooth separators were inserted, and to confirm the possibility of the transmission route from the medulla oblongata to the hypothalamus.METHODS： Two types of alternative orthodontic tooth separators（brass contact gauge and floss） were inserted into the right upper premolars of 10 healthy volunteers. Brain functional T2＊-weighted images and anatomical T1-weighted images were taken.RESULTS： The blood oxygenation level dependent（BOLD） signals following insertion of a brass contact gauge and floss significantly increased in the somatosensory association cortex and hypothalamic area.CONCLUSION： Our findings suggest the possibility of a transmission route from the medulla oblongata to the hypothalamus.

Surface-modified deproteinized human demineralized tooth matrix for bone regeneration:physicochemical characterization and osteoblast cell biocompatibility

Tooth presents an intriguing option as a bone graft due to its compositional similarity to bone.However,the deproteinized human demineralized tooth matrix(dpDTM),developed to overcome the limited availability of autologous tooth grafts,has suboptimal pore size and surface roughness.This study aimed to fabricate a surface-modified dpDTM using acid etching and collagen coating,followed by in vitro evaluation of physicochemical and biological properties.The dpDTM was modified into two protocols:Acid-modified dpDTM(A-dpDTM)and collagen-modified dpDTM(C-dpDTM).Results demonstrated that A-dpDTM and C-dpDTM had increased pore sizes and rougher surfaces compared to dpDTM.Collagen immobilization was evidenced by nitrogen presence exclusively in C-dpDTM.All groups had a Ca/P molar ratio of 1.67 and hydroxyapatite as the sole constituent,with 65-67%crystallinity.Degradation rates significantly increased to 30%and 20%for C-dpDTM and A-dpDTM,respectively,compared to 10%for dpDTM after 120 days.Cumulative collagen release of C-dpDTM on Day 30 was 45.16 mg/ml.Osteoblasts attachment and proliferation were enhanced on all scaffolds,especially C-dpDTM,which displayed the highest proliferation and differentiation rates.In conclusion,surface modified of dpDTM,including A-dpDTM and C-dpDTM,significantly enhances bioactivity by altering surface properties and promoting osteoblast activity,thereby demonstrating promise for bone regeneration applications.

基于任务清单的柔性拔牙CBL病例资料库的构建与应用价值

目的 探讨基于任务清单的柔性拔牙CBL病例资料库的构建与应用。方法 本研究在开展柳传志环(PDF环)结合“以病例为引导”的教学法应用于牙槽外科临床带教的基础上,选择阻生牙微创拔除术为经典案例,应用于临床带教,开展柔性拔牙临床医学人文教育。结果 构建基于任务清单的柔性拔牙CBL病例资料库具有较强的临床实用性和较好的客观性,对实习医师医学人文素养的培育、临床思维能力的培养、自我学习能力的激发、发散思维模式的训练、知识体系的逻辑性归纳等方面有着明显优势。结论 本研究基于任务清单的柔性拔牙CBL病例资料库的构建具有较大的优势,能够使其成为带教教师不断学习和临床带教的手段,值得广泛应用于临床实习带教。

基于SINUMERIK ONE的展成磨齿面扭曲修形模块开发

为了实现对齿向修形齿轮磨削时齿面扭曲的补偿,在研究SINUMERIK ONE数字化原生数控系统及其3GL开发软件基础上,以新型蜗杆砂轮磨齿机为研究对象,利用QT设计人机界面UI,用VS C++完成前端与后端设计,开发了蜗杆砂轮磨齿机扭曲修形模块。在人机界面上通过输入齿面修形参数和齿廓倾斜偏差,实现齿轮扭曲齿面补偿的自动化修形加工,极大地提高了磨齿机的开发效率与加工效率。

TNF-α通过ERK1/2-Runx2信号通路调控SHED成骨分化能力的实验研究

目的:探讨肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)对人脱落乳牙牙髓干细胞(stem cells from human exfoliated deciduous teeth,SHED)骨分化能力的影响,分析ERK1/2-Runx2信号通路在该调控过程中的变化。方法:从6~8岁健康儿童正常乳恒牙替换即将脱落的乳切牙中分离和培养SHED,取第三代细胞,分为对照组(成骨诱导剂培养)、观察组(成骨诱导剂和TNF-α共培养)和激动剂组(成骨诱导剂、TNF-α和ERK通路激动剂共培养)。采用茜素红染色评价成骨分化功能,采用Western印迹检测SHED细胞中Osterix、OPN、ERK1/2、pERK1/2和Runx2的蛋白表达水平,应用qRT-PCR检测Osterix、OPN、ERK1/2、pERK1/2和Runx2 mRNA的表达。采用SPSS 26.0软件包对数据进行统计学分析。结果:3组细胞成骨分化能力比较结果显示,3组细胞中均可见红棕色矿化结节。3组组间相比,对照组矿化结节最多,激动剂组次之,观察组最少。与对照组相比,观察组和激动剂组的Osterix、OPN蛋白和mRNA表达水平显著下降,而激动剂组Osterix、OPN蛋白和mRNA表达水平显著高于观察组;3组细胞的ERK1/2蛋白和mRNA表达水平无显著差异,而观察组和激动剂组pERK1/2和Runx2的蛋白和mRNA表达水平显著高于对照组,激动剂组的蛋白及mRNA表达水平显著高于观察组。结论:TNF-α对SHED成骨分化具有抑制作用,该作用可能与抑制ERK1/2-Runx2信号通路有关。

Co-firing of levator palpebrae and masseter muscles links the masticatory and oculomotor system in humans

Simultaneous co-firing of the levator palpebrae （LP） and pterygoid muscles were recorded in Marcus Gann Syndrome （MGS） patients in early clinical studies. ＂Release hypothesis＂ proposed an intrinsic masticatory oculo- motor neural circuit and this kind circuit, which, however, has been observed only in amphibian. On the other hand, congenital miswiring hypothesis has overwhelmed other interpretations. However, the same phenomenon visualized in MGS cases was unveiled in human subjects without any sign of congenital oculomotor disorder. To further study co-firing of the upper eyelid and jaw muscles, we applied non-invasive EMG recording of the upper eyelid and ipsilateral masseter muscle belly in nine healthy volunteers. LP activity was determined initially by looking upward and active retraction of upper eyelid with head fixed. Then, dual channel inputs from upper eyelid and masseter muscle was recorded during tooth occlusion motivated by isometric masseter muscle contraction without jaw and face moving. The EMG recorded from upper eyelid when the subjects retracted eyelid with head fixed exhibited the same pattern as that collected during tooth occlusion, but the pattern was completely different from EMG of active eye closure. This reflects tooth occlusion evoked LP activity. Then, simultaneous co-firing of the LP and masseter muscle was recorded simultaneously during tooth occlusion without jaw movement. Finally, the aforemen- tioned co-firing was recorded when the subjects conducted rhythmic occlusion and synchronous EMG from both muscles was acquired. In conclusions, humans may also have an intrinsic masticatory oculomotor circuit and release hypothesis may apply, at least, to some cases of MGS.

Structural Changes in Human Teeth after Heating up to 1200°C in Argon Atmosphere

The phase transformation of hydroxyapatite (HAP, Ca10(PO4)6(OH)2) to the beta tricalcium phosphate phase (β-TCP, β-Ca3(PO4)2) at 1100°C is well known. However, in the case of human tooth, the HAP phase transformation is still an open area. For example, the CaO phase has sometimes been reported in the set of phases that make up the teeth. In this study, physical changes of human teeth when subjected to heat treatment in inert atmosphere (argon) were studied. The results were compared with those obtained in air atmosphere, from room temperature (25°C) up to 1200°C. Morphological changes were analyzed by light and scanning electron microscopy (SEM). The HAP to β-TCP phase transformation was followed in powder samples by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Heating of teeth results in the removal of organic material and structural water before the HAP to β-TCP phase transformation, the increment in hardness and the induced crystal growth. The percentage of the phases, crystal growth and lattice parameter variations as a function of temperature was quantified by Rietveld analysis. The black color was observed in dentin heated under argon atmosphere. Differences in expansivity produce fractures in dentin at 300°C in argon and at 400°C in air. In dentin, the coexistence of the HAP and β-TCP phases was observed after 800°C in argon and after 600°C in air;in enamel it was observed at 600°C in argon compared with 400°C in air. In general, the role played by the argon atmosphere during the thermal treatment of the teeth is to retard the processes observed in air.

High-Resolution ¹H NMR Investigations of the Oxidative Consumption of Salivary Biomolecules by a Tooth-Whitening Formulation: Relevance to Safety Issues

A multicomponent evaluation of the oxidative consumption of salivary biomolecules by a hydrogen peroxide (H2O2)-containing tooth-whitening formulation has been performed using high-resolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Unstimulated human saliva samples (n = 10) were treated with aliquots of supernatants derived from 1) the H2O2-containing whitening gel, 2) the corresponding tooth-whitening accelerant solution containing an amino-alcohol activator, and 3) a combination of these product agents pre-mixed in the recommended manner. 600 MHz 1H NMR spectra acquired on these samples demonstrated that H2O2 present in the whitening gel gave rise to the oxidative decarboxylation of salivary pyruvate (to acetate and CO2), the direct oxidation of trimethylamine and methionine (to trimethylamine-N-oxide and methionine sulphoxide respectively), and the indirect oxidative consumption of lactate and carbohydrates in general. Experiments conducted on a chemical model system confirmed the consumption of pyruvate by added H2O2, and also revealed that this method could be employed for determinations of the H2O2 content of tooth-whitening products. In conclusion, high-resolution 1H NMR analysis provides much valuable molecular information regarding the fate of tooth-whitening oxidants in human saliva, and also permits an assessment of the ability of endogenous antioxidants therein to protect against any soft tissue damage arising from the possible leakage of H2O2 from tooth-whitening application trays.

Neural crest derived stem cells from dental pulp and tooth-associated stem cells for peripheral nerve regeneration

The peripheral nerve injuries,representing some of the most common types of traumatic lesions affecting the nervous system,are highly invalidating for the patients besides being a huge social burden.Although peripheral nervous system owns a higher regenerative capacity than does central nervous system,mostly depending on Schwann cells intervention in injury repair,several factors determine the extent of functional outcome after healing.Based on the injury type,different therapeutic approaches have been investigated so far.Nerve grafting and Schwann cell transplantation have represented the gold standard treatment for peripheral nerve injuries,however these approaches own limitations,such as scarce donor nerve availability and donor site morbidity.Cell based therapies might provide a suitable tool for peripheral nerve regeneration,in fact,the ability of different stem cell types to differentiate towards Schwann cells in combination with the use of different scaffolds have been widely investigated in animal models of peripheral nerve injuries in the last decade.Dental pulp is a promising cell source for regenerative medicine,because of the ease of isolation procedures,stem cell proliferation and multipotency abilities,which are due to the embryological origin from neural crest.In this article we review the literature concerning the application of tooth derived stem cell populations combined with different conduits to peripheral nerve injuries animal models,highlighting their regenerative contribution exerted through either glial differentiation and neuroprotective/neurotrophic effects on the host tissue.

安徽萧县金寨遗址大汶口文化中晚期墓葬出土人骨的研究

安徽萧县金寨遗址2016至2018年度考古发掘中出土了74例大汶口文化中晚期人骨材料。本文对这批人骨材料的性别、年龄和相关现象进行鉴定、判断,认为金寨遗址居民死亡年龄段集中在壮年期。人骨材料中发现大汶口文化居民常见的人工拔牙和枕部变形现象,从人类骨骼考古视角为探讨大汶口文化向皖北地区的扩张提供了重要证据。与大汶口文化核心地区的遗址相比,金寨遗址古代居民拔牙率与枕部变形率偏低,这种式微或许说明大汶口文化在向皖北扩张过程中似乎受到不同文化或理念的影响。

重组人转化生长因子-β1对大鼠正畸牙移动模型成骨细胞分化及ERK/MAPK信号通路的影响

目的:探讨重组人转化生长因子-β1(rhTGF-β1)对大鼠正畸牙移动模型细胞外信号调节激酶(ERK)/丝裂原活化蛋白激酶(MAPK)信号通路及成骨细胞分化的影响。方法:将SD大鼠随机分为:对照组、模型组、rhTGF-β1低剂量组、rhTGF-β1中剂量组、rhTGF-β1高剂量组。模型组、rhTGF-β1低、中、高剂量组建立大鼠正畸牙移动模型,各组从造模第1天开始给药,rhTGF-β1(低、中、高)剂量组于双侧上颌第一磨牙近中牙龈黏膜下分别注射1.25、2.5、5 ng/mL的rhTGF-β1溶液0.1 mL,对照组注射0.1 mL生理盐水,每2 d给药1次,持续14 d。游标卡尺测量大鼠上颌第一磨牙移动距离;苏木精-伊红染色观察大鼠牙周及牙槽骨组织病理形态;酶联免疫吸附法检测血清肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、骨保护素(OPG)、核因子κB受体活化因子配体(RANKL)水平;Western blot检测大鼠牙周及牙槽骨组织成骨相关蛋白[骨钙素(OCN)、骨桥蛋白(OPN)、Runt相关转录因子2(Runx2)]和ERK/MAPK通路相关蛋白表达。结果:与对照组相比,模型组大鼠牙张力侧牙周组织膜纤维拉伸变长,组织间隙变宽,基质增生,成骨细胞数量大量减少近乎消失,呈现病理损伤,上颌第一磨牙移动距离、血清TNF-α、IL-6、RANKL、牙周及牙槽骨组织p-ERK1/2/ERK1/2、p-p38 MAPK/p38 MAPK蛋白表达水平明显升高,血清OPG、牙周及牙槽骨组织OCN、OPN、Runx2蛋白表达水平明显降低(P<0.05);与模型组相比,rhTGF-β1低、中、高剂量组大鼠牙张力侧牙周及牙槽骨组织病理损伤逐步减轻,血清TNF-α、IL-6、RANKL、牙周及牙槽骨组织p-ERK1/2/ERK1/2、p-p38 MAPK/p38 MAPK蛋白表达水平依次降低,上颌第一磨牙移动距离、血清OPG、牙周及牙槽骨组织OCN、OPN、Runx2蛋白表达水平依次升高(P<0.05),且各组之间呈剂量依赖性。结论:rhTGF-β1可减轻大鼠正畸牙移动模型炎症反应,促使成骨分化,加速正畸牙移动,可能与抑制ERK/MAPK信号通路激活有关。

重组人生长激素对正畸牙移动和牙根吸收影响的动物实验研究

目的:研究重组人生长激素(Recombinanthuman growthhormone,rhGH)对大鼠牙根吸收模型正畸牙移动和牙根吸收的影响。方法:选择实验动物中心提供的健康Wistar雄性大鼠40只,使用单纯随机抽样法分为生长激素组和对照组,各20只。两组均于恒温环境下按照实验动物管理和使用指南对所有大鼠进行饲养和处理。为两组大鼠安装矫治器,并从安装矫治器当天起,生长激素组按照每天2mg/kg的总剂量对大鼠注射生长激素,分两次注射(即单次1mg/kg);对照组按照相同剂量和频率对大鼠进注射生理盐水。对比不同时点两组大鼠牙移动距离、牙根吸收指数、胰岛素样生长因子I(Insulin-like growth factor I,IGF-I)阳性破骨细胞数和阳性牙周膜细胞数。结果:与对照组相比,第7、14天生长激素组牙移动距离较远,差异有统计学意义(P<0.05)。与对照组相比,第5、7、14天生长激素组牙吸收指数较低,差异有统计学意义(P<0.05)。生长激素组阳性破骨细胞数第1天至第5天呈上升趋势,第5天至第14天呈下降趋势;对照组阳性破骨细胞数第1天至第7天呈上升趋势,第7天至第14天呈下降趋势;两组阳性牙周膜细胞数第1天至第14天呈上升趋势,差异均有统计学意义(P<0.05)。与对照组相比,生长激素组第5天阳性破骨细胞数较多、第7天阳性破骨细胞数较少,第5、7、14天阳性牙周膜细胞数较多,差异均有统计学意义(P<0.05)。结论:rhGH有利于减轻正畸引起的牙根吸收,加快牙移动以缩短牙齿正畸治疗的时间,其原因可能是rhGH通过促进IGF-I的表达使破牙骨质细胞减少,以缓解牙根吸收。

甲硝唑联合重组人表皮生长因子预防拔牙术后干槽症的效果研究

目的:研究甲硝唑联合重组人表皮生长因子预防拔牙术后干槽症的效果。方法:选择重庆市东南医院口腔科在2019年1月至2020年1月期间收治的60例拔除下颌阻生智齿的患者作为本次研究的对象,然后按照随机数表法对所选对象进行分组,分成阿莫西林组(n=30)和甲硝唑-生长因子组(n=30)。阿莫西林组进行拔牙手术治疗后在干槽内不放置填充物,只通过服用阿莫西林预防干槽症。甲硝唑-生长因子组进行拔牙手术治疗后于干槽内添加甲硝唑联合重组人表皮生长因子明胶海绵预防干槽症。比较两组患者的干槽症发生率、治疗前后的疼痛评分、治疗前后的生活质量(睡眠质量、心理状态、躯体活动、社会生活)。结果:甲硝唑-生长因子组患者的干槽症发生例数为2例,发生率为6.67%(2/30);阿莫西林组患者的干槽症发生例数为9例,发生率为30.00%(9/30);甲硝唑-生长因子组患者的干槽症发生率低于阿莫西林组患者,差异有统计学意义(P<0.05)。治疗前,两组患者的疼痛评分比较,差异无统计学意义(P>0.05)。治疗后,甲硝唑-生长因子组患者的疼痛评分为(2.46±0.54)分,阿莫西林组患者的疼痛评分为(4.19±1.16)分;甲硝唑-生长因子组患者的疼痛评分低于阿莫西林组患者,差异有统计学意义(P<0.05)。治疗前,两组患者的睡眠质量、心理状态、躯体活动、社会生活评分比较,差异无统计学意义(P>0.05)。治疗后,甲硝唑-生长因子组患者的睡眠质量、心理状态、躯体活动、社会生活评分均高于阿莫西林组患者,差异有统计学意义(P<0.05)。结论:拔牙手术后,应用甲硝唑联合重组人表皮生长因子进行预防性治疗,能够有效降低干槽症的发生率,改善患者疼痛症状以及生活质量,值得推广。

乳磨牙固连的研究进展

乳磨牙固连是牙齿萌出异常的一种,固连部位牙周膜消失,表现为根骨黏连;发病率为1.3%~8.9%,乳牙列中最易受累牙位为下颌第一乳磨牙,混合牙列中为第二乳磨牙。乳磨牙固连病因可能与遗传因素、局部牙槽骨或牙骨质矿化代谢的相关信号通路、Malassez上皮剩余细胞分泌的细胞因子、牙根生理性吸收过程中的炎症反应等有关。乳磨牙固连可通过临床表现及影像学检查诊断,根据低位咬合程度分为轻、中、重度。因其可引起咬合紊乱、脱落延迟及牙槽骨发育不足等并发症,故需儿童口腔科、正畸科、牙周科、修复科等多学科联合治疗,综合考虑患者年龄、低位咬合严重程度及是否存在继承恒牙等因素制定长期治疗方案。本文就乳磨牙固连的病因、发病机制、诊断、并发症、治疗等方面进行综述,以期为乳磨牙固连的临床诊治提供参考。

人体天然牙不同深度层次的显微硬度与耐磨性的研究

采用显微硬度计测定人体天然牙不同深度层次 (牙釉质、釉牙本质界及牙本质 )的显微硬度 ,并在改进后的微动试验台上对其相应区域进行了模拟牙齿摩擦副的摩擦磨损试验研究。结果发现 ,显微硬度 :牙釉质的为3 2 0 .40± 2 2 .77HV,釉牙本质界 2 3 2 .2 6± 3 2 .3 1HV,牙本质 61.17± 9.42 HV( P<0 .0 5 ) ;磨痕深度 :牙釉质的为17.3 3± 0 .5 8μm,釉牙本质界 49.44± 16.47μm,牙本质 95 .2 0± 15 .0 7μm( P<0 .0 5 ) ;牙釉质的耐磨性明显高于牙本质 。

人牙釉质在人工唾液润滑下与不同偶件对摩时的摩擦学性能研究

在往复滑动摩擦磨损试验台上对比考察了人牙釉质自配副及其同钛合金和纯钛配副时的摩擦学性能.结果表明:牙釉质/牙釉质的稳态摩擦系数约为1.00,其磨损表面釉柱清晰可见,磨损机制表现为剥落和轻微犁削并存;牙釉质/钛合金的稳态摩擦系数约为0.92,磨损表面既有犁沟又有剥落,可以看到轮廓分明的釉柱;牙釉质/纯钛的稳态摩擦系数约为0.87,磨损表面存在纯钛转移膜.从摩擦系数的变化趋势、稳态摩擦系数的大小、磨损表面形貌和磨痕深度等角度来看,牙釉质/钛合金与牙釉质/牙釉质的摩擦磨损行为较为相似.

氟对体外器官培养人牙胚骨形成蛋白表达的影响

目的 通过研究氟对牙胚发育早期骨形成蛋白 (BMP)表达的影响 ,初步探讨氟在早期牙胚发育中的可能作用机制。方法 4个月的人胚胎 ,取乳牙胚用RPMI16 4 0培养液进行器官培养 8d。免疫组化法研究 2 5mg·L-1和 5 0mg·L-1的氟对分泌前期牙胚的影响 ,观察培养第 2、4、6、8天时BMP表达的变化。采用图像分析仪对免疫组化染色结果进行灰度分析。结果 BMP的表达主要在造釉器。成釉细胞 ,中间层细胞和星网状层细胞均有BMP表达 ,牙乳头细胞或成牙本质细胞不表达BMP。 2 5mg·L-1氟时从培养第 6天开始BMP表达增强 ;5 0mg·L-1氟时从培养第 2天到第 6天BMP的表达增强 ,培养第 8天时BMP的表达降低。

人牙釉质的磨损机制研究

以钛合金为对摩材料,考察了人牙釉质在人工唾液介质中的滑动磨损进程,结合微观分析,研究了牙釉质的磨损机制。结果表明:在摩擦过程中,随着釉质表面发生脆性剥落,磨损从两体接触磨损转变为三体磨粒磨损,磨损加剧;随着接触时间增长,硬质磨屑尺寸变小,磨损率降低,进入稳定磨损阶段。牙釉质磨损为机械磨损过程,釉质表面基本无摩擦化学作用。