新型激光光敏根管消毒剂在牙本质中渗透性的研究

目的：观察新型激光光敏根管消毒剂、甲苯胺蓝和亚甲基蓝在牙本质中的渗透效果,评价三种光敏剂在牙本质中的渗透性。方法：收集新鲜拔除的离体单根管牙90颗,根管预备后随机分为三组。每组30颗。A组为新型激光光敏根管消毒剂组;B组为甲苯胺蓝组;c组为亚甲基蓝组。A、B、C三组实验根管内分别用浸有饱和的新型激光光敏根管消毒剂、甲苯胺蓝和亚甲基蓝的棉捻在根管内停留60秒。沿牙体长轴颊舌纵向劈开,倒置荧光显微镜下观察并拍照,用Photoshop8．01软件测量三种光敏剂渗透入牙本质的平均深度。结果：新型激光光敏根管消毒剂在牙本质内的渗透平均深度为553．25μm,甲苯胺蓝在牙本质内的渗透平均深度为350．75μm,亚甲基蓝在牙本质内的渗透平均深度为168．25μm。结论：新型激光光敏根管消毒剂在牙本质渗透性明显优于甲苯胺蓝和亚甲基蓝,具有良好的牙本质渗透性。     

Er,Cr:YSGG激光照射对根管封闭效果影响的实验研究

探讨常规根管预备后使用不同能量参数Er,C r:YSGG激光进行根管内照射对根管封闭效果的影响,为此激光在根管治疗领域的临床应用提供重要的实验依据。选择新拔除的单根管牙80颗,分成4组,每组20颗牙。常规根管预备后,分别使用1 W、2 W、3 W Er,C r:YSGG激光于有水条件下进行根管内照射,另选一组不做任何处理,作为阴性对照。扫描电子显微镜下观察根管内壁形态学改变后,常规根管充填,检测根管微渗漏情况。采用单因素方差分析及q检验进行统计学处理。结果可见:(1)形态学观察:与对照组相比,激光照射均可有效去除根管内壁的玷污层及碎屑;牙本质小管口清晰可见;未见熔融及炭化等热损伤改变;其中3 W激光处理后根管内壁形态最为理想。(2)微渗漏检测:与对照组相比,各激光组根管微渗漏深度均显著减少(P<0.05);但各激光组间比较无显著性差异(P>0.05)。综上,使用Er,C r:YSGG激光进行根管内照射可达到较为理想的根管清洁目的,显著改善根管充填后的封闭效果,因此有望在临床上应用提高根管治疗的成功率。     

奥硝唑用于感染根管消毒的细菌学研究

目的　观察和探讨新型抗厌氧菌药物奥硝唑消毒感染根管的抗菌效果。方法　选择感染根管患牙98颗,常规根管预备后,随机分为试验组(奥硝唑组)和对照组(甲醛甲酚组)各4 9颗。分别在根管预备前、预备后及封药后进行根管内细菌标本采样、培养、分离与鉴定,测定根管内细菌变化及检出情况,并观察封药后临床症状和体征的变化。结果　2组封药后,根管内细菌数量及检出率均较封药前明显降低( P<0 .0 5 ) ,根管内细菌数量及检出率比较,差异无显著性( P>0 .0 5 ) ,奥硝唑的近期临床疗效优于甲醛甲酚。结论　奥硝唑是一种较安全、有效的根管消毒药物     

光敏剂甲苯胺蓝在口腔颊粘膜渗透性的研究

目的:研究不同时间,甲苯胺蓝(Toluidine Blue O,TBO)在大鼠炎症性口腔颊粘膜渗透的浓度变化,及甲苯胺蓝与炎症细胞分布之间的关系。方法:实验选取wistar大鼠32只,炎症组大鼠20只,建立以金葡菌为优势菌的感染炎症创口模型。将浓度为1mg/mL甲苯胺蓝溶液置于大鼠感染炎症创口组织上5、10分钟后处死,正常粘膜组大鼠8只,于甲苯胺蓝在正常颊粘膜渗透5、10、20、40分钟后处死,避光条件下取组织块进行冰冻切片,即刻荧光显微镜下观察荧光分布;冰冻切片进行HE染色,观察炎症细胞分布。采用Image Pro-plus 6.0软件检测荧光分布的光密度、分布面积以及炎症分布面积。结果:1创口周围正常粘膜及正常完整粘膜组的甲苯胺蓝均停留在角化层,未穿透上皮层,和时间无相关关系;2炎症5分钟组平均荧光分布可达到炎症细胞分布面积的89%,炎症10分钟组可达108%;炎症组在创口表面及深部,荧光光密度均无显著差异。结论:1甲苯胺蓝可有效分布于感染的炎症组织,但不能穿透正常组织,完整上皮可保护正常组织免受光动力的杀伤。2浓度为1 mg/mL的甲苯胺蓝溶液渗透时间为10分钟时,创口中甲苯胺蓝的分布与炎症细胞的分布基本一致,甲苯胺蓝浓度梯度无显著变化。提示甲苯胺蓝作为光敏剂在针对口腔创口感染的抗菌光动力疗法中可有效、安全的发挥作用。     

两种根管冲洗液对狗牙根管内细菌抗菌作用的实验研究

目的观察2%洗必泰溶液和3%双氧水2种根管冲洗液对狗牙根管内粪肠球菌、溶血链球菌、微小消化链球菌、中间普氏菌及具核酸杆菌的影响,为临床根管治疗提供参考。方法选择成年健康杂种狗3只,共有24个实验牙,48个实验牙根。于狗牙根管内接种粪肠球菌、溶血链球菌、微小消化链球菌、中间普氏菌及具核酸杆菌。对狗牙完成根管治疗。于治疗后12个月拍摄根尖X线片,并记录牙齿和根尖周组织的临床表现。将患牙随机分为3组,每组7颗患牙,去除根管内充填物并进行根管预备,实验一组用2%洗必泰溶液冲洗根管,实验二组用3%双氧水冲洗根管,对照组用0.9%NaC l溶液冲洗根管。分别在根管预备前及根管预备冲洗后对根管内细菌取样,培养,鉴定并记录细菌菌落数量,测定根管内细菌变化情况。结果根管预备冲洗后3组根管内的细菌量均较根管预备前显著下降（P〈0.05）。2%洗必泰溶液和3%双氧水2种根管冲洗液的杀菌效果明显好于0.9%NaC l溶液（P〈0.05）,2%洗必泰溶液明显好于3%双氧水（P〈0.05）。结论2%洗必泰溶液是有效的根管冲洗药物,可明显减少狗牙根管内粪肠球菌、溶血链球菌、微小消化链球菌、中间普氏菌及具核酸杆菌的数量,但不能完全清除根管内的细菌。     

抗菌光动力疗法应用于乳前牙治疗对髓腔内微生物的影响CSCD

目的 旨在评估常规牙髓治疗后抗菌光动力疗法(a-PDT)对乳前牙髓腔内微生物的影响。方法 选择2020年12月就诊于郑州大学附属医院口腔科儿童的62颗牙髓坏死的乳前牙,随机分为常规根管治疗组(A组)和常规根管治疗联合a-PDT治疗组(B组),每组各31颗。a-PDT使用浓度为0.005%的亚甲蓝作为光敏剂,用无菌纸制锥形管在根管内部涂抹3 min,用激光在根管入口处直接照射40 s(波长:660 nm,能量密度:4 J/cm^(2),功率:100 mW)。使用锥形管采集两组患者根管内的微生物样本(两组均在治疗前和治疗后立即采集)进行培养。治疗后1个月和3个月进行临床随访,包括瘘管和牙齿活动度等。结果 与治疗前比较,A组治疗后细菌载量减少了93%,B组减少了99%,差异无统计学意义(P>0.05);治疗后1个月和3个月,两组康复情况比较差异无统计学意义(P>0.05)。结论 常规治疗联合a-PDT可有效杀灭乳牙内微生物。     

光动力作用对铜绿假单胞杆菌杀伤效应的研究

目的:探讨不同的光动力剂量下光动力疗法(photodynam ic therapy,PDT)对体外培养的铜绿假单胞杆菌的杀伤效应。方法:以耐药性较强的铜绿假单胞杆菌(Pseudom onas aeruginos,P.aeruginosa)为研究对象,采用亚甲基蓝(m ethylene b lue,MB)作为光敏剂,用656 nm的激光作为光源(m axoutput=300 mW),对不同系列浓度的MB进行不同剂量的光照,用菌落计数的办法来观测PDT对铜绿假单胞杆菌的杀伤作用;同时利用血培养基检测铜绿假单胞杆菌致病性的改变。结果:在光照剂量相同的情况下,浓度适中(131.7 m ol)的亚甲基蓝溶液能够有效地杀伤铜绿假单胞杆菌,使其致病性降低;而浓度较高(1 317 m ol)或较低(13.17 m ol)的亚甲基蓝溶液对铜绿假单胞杆菌的杀伤作用相对较弱。结论:光动力作用对体外培养的铜绿假单胞杆菌具有明确的杀伤作用,但是其效果和剂量关系密切,所以在治疗过程中必须寻找合适的光敏剂剂量。     

脉冲Nd∶YAG激光在根管预备中的临床应用——与超声根管预备、传统手动根管预备比较

为了观察脉冲Ｎｄ∶ＹＡＧ激光在根管预备（以下简称根备）中的作用,我们用Ｎｄ∶ＹＡＧ激光辅助,对３０颗患牙进行根备,根备后即时根充。并与超声根备后即时根充、传统根备后即时根充比较,结果表明：激光组的术后疼痛反应少于超声组与传统组,远期疗效与超声组相仿,而优于传统组。     

脉冲Nd：YAG激光在根管预备中的临床应用

为了观察脉冲Ｎｄ：ＹＡＧ激光在根管预备（以下简称根备）中的作用,我们用Ｎｄ：ＹＡＧ激光辅助,以３０颗患牙进行根备,根备后即时根充。并与超声根备后即时根充、传统根备后即时根充比较,结果表明：激光组的术后疼痛反应少于超声组与传统组,远期疗效与超声组相仿,而优于传统组。     

慢性根尖周炎应用氢氧化钙根管内封药的临床疗效观察

目的:观察慢性根尖周炎患牙用氢氧化钙根管内封药的临床疗效。方法:选择100例慢性根尖周病变患者随机分为实验组和对照组各50例;观察组用氢氧化钙做根管内封药;对照组用甲醛甲酚做根管内封药,观察术后1周的临床及X线片表现,并分析评定临床疗效。结果:术后1周有效率比较,观察组为96%,对照组为86%;两组间疗效差异具有统计学意义。结论:氢氧化钙是较理想的根管内消毒剂。     

Dentin hardness differences across various mammalian taxa

Differences in dentin microstructure have been used as a tool for dietary reconstruction; however, the extent that diet is associated with this aspect of dental morphology has yet to be empirically tested. We conducted microhardness tests of mammalian dentin sections, hypothesizing that species with adaptations to particularly hard diets would have softer dentin, owing to a higher proportion of soft intertubular dentin. Species adapted to abrasive diets, in contrast, should have harder dentin, resulting from a higher proportion of hypermineralized peritubular dentin. We examined molar dentin hardness in ten mammalian taxa with durophagous diets, abrasive diets, and a comparative “control” group of mechanical generalists. Samples included six primate taxa and four non-primate species representing various dietary regimes. Our results reveal significant variation among taxa in overall hardness, but the data do not distinguish between hard and abrasive diets. Several taxa with generalized (i.e., mechanically diverse) diets resemble each other in exhibiting large variance in hardness measurements and comparably soft dentin. The high variation in these species appears to be either a functional signal supporting the niche variation hypothesis or indicate the absence of sustained unidirectional selective pressure. A possible phylogenetic signal of dentin hardness in the data also holds promise for future systematic investigations.     

Transgenic Expression of Dentin Phosphoprotein Inhibits Skeletal Development

Dentin sialophosphoprotein (DSPP) is proteolytically processed into an NH₂-terminal fragment called dentin sialoprotein (DSP) and a COOH-terminal fragment known as dentin phosphoprotein (DPP). These two fragments are believed to perform distinct roles in formation of bone and dentin. To investigate the functions of DPP in skeletal development, we generated transgenic mice to overexpress hemagglutinin (HA)-tagged DPP under the control of a 3.6 kb type I collagen (Col1a1) promoter (designated as Col1a1-HA-DPP). The Col1a1-HA-DPP transgenic mice were significantly smaller by weight, had smaller skeletons and shorter long bones than their wild type littermates, as demonstrated by X-ray radiography. They displayed reduced trabecular bone formation and narrower zones of proliferative and hypertrophic chondrocytes in the growth plates of the long bones. Histological analyses showed that the transgenic mice had reduced cell proliferation in the proliferating zone, but lacked obvious defects in the chondrocyte differentiation. In addition, the transgenic mice with a high level of transgene expression developed spontaneous long bone fractures. In conclusion, overexpressing DPP inhibited skeletal development, suggesting that the balanced actions between the NH₂- and COOH-terminal fragments of DSPP may be required for normal skeletal development.Key words: Dentin sialophosphoprotein, dentin phosphoprotein, development, bone, transgenic mice, growth plate     

Effects of Fluoridated Milk on Root Dentin Remineralization

Background

The prevalence of root caries is increasing with greater life expectancy and number of retained teeth. Therefore, new preventive strategies should be developed to reduce the prevalence of root caries. The aim of this study was to investigate the effects of fluoridated milk on the remineralization of root dentin and to compare these effects to those of sodium fluoride (NaF) application without milk.

Methods

Thirty extracted human molars were divided into 6 groups, and the root cementum was removed from each tooth. The dentin surface was demineralized and then incubated with one of the following six solutions: Sodium chloride NaCl, artificial saliva, milk, milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Serial sections were cut through the lesions and investigated with polarized light microscopy and quantitative morphometry, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The data were statistically evaluated using a one-way ANOVA for multiple comparisons.

Results

The depth of the lesion decreased with increasing fluoride concentration and was the smallest after incubation with artificial saliva+10 ppm fluoride. SEM analysis revealed a clearly demarcated superficial remineralized zone after incubation with milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Ca content in this zone increased with increasing fluoride content and was highest after artificial saliva+10 ppm fluoride incubation. In the artificial saliva+10 ppm fluoride group, an additional crystalline layer was present on top of the lesion that contained elevated levels of F and Ca.

Conclusion

Incubation of root dentin with fluoridated milk showed a clear effect on root dentin remineralization, and incubation with NaF dissolved in artificial saliva demonstrated a stronger effect.     

Dentin Matrix Protein 1 and Dentin Sialophosphoprotein in Human Sound and Carious Teeth: An Immunohistochemical and Colorimetric Assay

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are extracellular matrix proteins produced by odontoblasts involved in the dentin mineralization. The aim this study was to compare the distribution of DMP1 and DSPP in human sound dentin vs human sclerotic dentin. Sixteen sound and sixteen carious human molars were selected, fixed in paraformaldehyde and processed for immunohistochemical detection of DMP1 and DSPP by means of light microscopy, transmission electron microscopy (TEM) and high-resolution field emission in-lens scanning electron microscopy (FEI-SEM). Specimens were submitted to a pre-embedding or a post-embedding immunolabeling technique using primary antibodies anti DMP1 and anti-DSPP and gold-conjugated secondary antibodies. Other samples were processed for the detection of DMP1 and DSPP levels. Dentin from these samples was mechanically fractured to powder, then a protein extraction and a protein level detection assay were performed. DMP1 and DSPP were more abundant in carious than in sound samples. Immunohistochemical analyses in sclerotic dentin disclosed a high expression of DMP1 and DSPP inside the tubules, suggesting an active biomineralization of dentin by odontoblasts. Furthermore, the detection of small amounts of these proteins inside the tubules far from the carious lesion, as shown in the present study, is consistent with the hypothesis of a preventive defense of all dentin after a noxious stimulus has undermined the tooth.Key words: sclerotic dentin, dentin matrix protein, dentin sialophosphoprotein, immunohistochemistry     

不同年龄组修复性牙本质生成情况探讨

目的观察不同年龄段人的牙齿在受到龋损刺激后,修复性牙本质的生成情况。方法收集5组不同年龄组含有牙本质浅层龋的离体牙,每组各5颗牙齿。制作标本切片,HE染色,显微镜下观察。测量修复性牙本质厚度,作统计学检验。结果5组不同年龄牙齿的修复性牙本质平均厚度分别为:3.36、2.6、2.8、4.2、3.36,统计学检验无明显差异。结论受龋损刺激后,不同年龄牙齿的修复性牙本质生成情况无明显差异。     

Dentin sialoprotein and dentin phosphoprotein overexpression during amelogenesis

The gene for dentin sialophosphoprotein produces a single protein that is post-translationally modified to generate two distinct extracellular proteins: dentin sialoprotein and dentin phosphoprotein. In teeth, dentin sialophosphoprotein is expressed primarily by odontoblast cells, but is also transiently expressed by presecretory ameloblasts. Because of this expression profile it appears that dentin sialophosphoprotein contributes to the early events of amelogenesis, and in particular to those events that result in the formation of the dentino-enamel junction and the adjacent "aprismatic" enamel. Using a transgenic animal approach we have extended dentin sialoprotein or dentin phosphoprotein expression throughout the developmental stages of amelogenesis. Overexpression of dentin sialoprotein results in an increased rate of enamel mineralization, however, the enamel morphology is not significantly altered. In wild-type animals, the inclusion of dentin sialoprotein in the forming aprismatic enamel may account for its increased hardness properties, when compared with bulk enamel. In contrast, the overexpression of dentin phosphoprotein creates "pitted" and "chalky" enamel of non-uniform thickness that is more prone to wear. Disruptions to the prismatic enamel structure are also a characteristic of the dentin phosphoprotein overexpressing animals. These data support the previous suggestion that dentin sialoprotein and dentin phosphoprotein have distinct functions related to tooth formation, and that the dentino-enamel junction should be viewed as a unique transition zone between enamel and the underlying dentin. These results support the notion that the dentin proteins expressed by presecretory ameloblasts contribute to the unique properties of the dentino-enamel junction.