冷光漂白治疗对牙齿硬组织影响的扫描电镜观察

目的：观察BEYOND冷光漂白治疗对牙釉质表面及牙本质微结构的影响。方法：选用临床因正畸需要拔除A4、B4、C4和D4四颗健康前磨牙的患者12例作为受试者,每名受试者的D4作为空白对照牙,其余3颗牙予以BEYOND冷光漂白治疗。治疗结束后立刻拔除受试牙,分别制备牙釉质表面、牙本质纵剖和横剖观察面,以扫描电镜观察其微结构改变情况。结果：电镜显示BEYOND冷光漂白治疗后牙釉质表面出现溶融、脱矿现象;牙本质纵剖面可见管周牙本质轻微脱矿,管间牙本质胶原纤维网架塌陷;横剖面见牙本质小管口因脱矿而呈现不规则。结论：BEYOND冷光漂白可使牙釉质表层脱矿,并能透人到牙本质层使其微结构发生轻微改变。     

局部应用氟化物对酸蚀釉质作用的体外研究

目的：评价局部应用氟化物对酸蚀釉质的作用。方法：收集正畸减数拔除的年轻前磨牙40个，制备釉质样本，随机分成对照组，lg／L氟化钠液组，含氟牙膏组，联合应用组。用饮料对釉质间断性酸蚀1周，然后使用不同的氟化物处理酸蚀的釉质表面1周。采用显微硬度计检测釉质表面显微硬度值（SMH），原子力显微镜（AFM）、扫描电镜（SEM）观察牙体硬组织表面的结构。结果：饮料浸泡后釉质的SMH明显下降。与对照组相比，氟化物处理后各氟化物处理组的釉质SMH均有明显增加（P＜0．001）。AFM和SEM均可见酸蚀后的釉质表面呈典型的蜂窝状结构，SEM观察显示氟化物处理后，各组釉质表面均有一定沉积物。结论：饮料会导致体外釉质表面的脱矿，氟化物能够促进体外酸蚀釉质的再矿化。     

二极管激光和Pro-argin抛光膏治疗牙本质敏感症的研究

目的:研究二极管激光和Pro-argin抛光膏治疗牙本质敏感症(dentine hypersensitivity,DH)的临床效果。方法:选择80例DH患牙,随机分为A组(二极管激光治疗组,n=40)和B组(Pro-argin抛光膏治疗组,n=40),分别给予相应处理,处理前后评估患牙探诊敏感程度、VAS值。另外,选取健康离体牙制作牙本质切片,分别给予上述两种处理,扫描电子显微镜下观察牙本质小管状态。结果:A、B两组治疗后探诊敏感程度、VAS值均较治疗前明显减轻,差异有统计学意义(P<0.05),A、B两组间探诊敏感程度变化百分比、VAS值变化百分比相比无显著性差异(P>0.05);牙本质切片扫描电镜观察发现,经两种方法处理后,横剖面均可观察到绝大部分牙本质小管形成良好的管塞,纵剖面观察到A组形成厚度约10μm、相对均一的牙本质管塞,B组形成3～15μm、厚度不均一的牙本质管塞。结论:二极管激光与Pro-argin抛光膏均可用于即刻缓解DH疼痛。     

Er, Cr: YSGG激光与氟化物联合应用对牙体硬组织脱矿的影响

目的：体外研究Er，Cr：YSGG激光与氟化物联合应用对牙体硬组织抗酸性的影响。方法：标本随机分成4组，分别为对照组，激光组，氟处理组，激光＋氟组，进行不同处理后，0．1mol／L乳酸（pH4．8）脱矿24h，原子吸收分光光度计检测脱矿液中溶解的钙离子浓度，能谱分析仪进行氟原子含量分析，扫描电镜观察牙釉质和牙本质表面超微结构的变化。结果：激光组、氟处理组、激光＋氟组溶解的钙离子浓度都明显降低，与对照组有显著性差异（P〈0．05），但是激光＋氟组钙离子浓度仅略低于激光组、氟处理组，与其无显著性差异（P〉0．05）；氟含量的测定仅在氟处理组牙釉质和牙本质标本有氟峰出现；扫描电镜观察见，激光组：表面不平呈鳞片状、峭壁状，无玷污层，釉质结构清晰可见，牙本质小管开放，无熔融、炭化等热损伤的表现；氟化钠组：表面有大量玷污层和碎屑，并可见到许多小颗粒沉积在牙釉质和牙本质表面；激光＋氟组：表面结构与激光组相似，未见颗粒沉积。结论：Er，Cr：YSGG激光与氟化物无联合效应，其机制仍需进一步的研究与探讨。     

Croll法釉质微打磨和家庭漂白联合应用对牙釉质表面形态影响的离体牙研究

目的探讨牙齿Croll法釉质微打磨和家庭漂白联合使用对釉质表面形态的影响。方法12颗离体牙随机分为3组,A组为对照组,B组采用Croll法釉质微打磨法,C组采用Croll法釉质微打磨法后家庭漂白4周,通过对离体牙扫描电镜的观察,研究上述釉质微打磨和家庭漂白对釉质表面形态的影响。结果Croll法釉质微打磨可以使釉质表面形成致密的矿化结构,经过4周的家庭漂白,釉质表面有脱矿表现。结论Croll法釉质微打磨能形成致密的矿化表层,但漂白后釉质仍然脱矿。     

扫描电镜观察漂白剂对牙釉质和牙本质结构的影响

目的 观察不同浓度漂白剂治疗牙釉质，牙本质超微结构的变化。方法 分别用30%过氧化氢（1）组，16%过氧化脲（2）组，11%过氧化脲（3）组对离体牙牙釉质及牙本质进行6天治疗，SEM下观察。结果 （1）组牙釉质碚矿明显，牙本质因脱矿见有胶原纤维网架显露。（2）组釉质因脱矿晶体微细结构不清晰，牙本质内见有局灶性钙化减低灶。（3）组釉柱排列整齐无脱矿，牙本质内有局灶性钙化减低区。结论 高浓度过氧化氢可使牙釉质及牙本质表层脱矿部分结构遭到破坏，提示临床应用低浓度漂白剂安全有效。     

氟化物涂膜对正畸固定矫治中牙釉质脱矿影响的SEM研究

目的：采用扫描电镜（SEM）观察氟化物涂膜对抑制离体牙牙釉质脱矿及促进再矿化的功效。方法：选择因正畸需要拔除的前磨牙15颗,经37％磷酸处理,制备人工釉质脱矿标本,并用氟化物涂膜进行表面处理。采用SEM对标本脱矿前（对照组）,脱矿后（脱矿组）以及氟化物涂膜治疗后（治疗组）的表面形貌进行观察分析。结果：对照组与脱矿组之间、脱矿组与治疗组之间形态学存在显著差异,而对照组与治疗组之间形态学差异相对较小。结论：氟化物涂膜可有效改善釉质脱矿后的牙齿脱矿形貌。     

不同过氧化物对牙釉质结构和硬度的影响

目的:探究30%过氧化氢(hydrogen peroxide,HP)、22%过氧化脲(carbamide peroxide,CP)、3%过硼酸钠(sodium perborate,SP)对离体牙漂白后牙齿釉质表面结构和硬度的差异。方法:筛选正常人离体牙标本并随机分为A、B、C、D 4组,分别用生理盐水、30%过氧化氢、22%过氧化脲、3%过硼酸钠对4组牙齿进行漂白处理,最后对离体牙进行电镜扫描(×2000)和维氏硬度测定并进行统计分析。结果:实验组与对照组相比,扫描电镜显示: 30%过氧化氢和3%过硼酸钠组,其釉质表面呈散在的孔状,蜂窝状破坏,说明牙齿出现了不同程度的脱矿、溶解;22%过氧化脲组牙齿釉质表面结构基本完整,无明显脱矿和溶解现象;硬度测定结果显示:组间两两比较存在差异性(P＜0.05),漂白后4个组牙齿硬度大小是:对照组＞22%过氧化脲组＞3%过硼酸钠＞30%过氧化氢。结论:3种过氧化物漂白试剂中22%过氧化脲对牙釉质结构和硬度的影响最小。     

Longhurst釉质微打磨后漂白牙釉质表面形态的扫描电镜观察

目的：观察牙齿Longhurst法釉质微打磨以及与家庭漂白联合应用后釉质表面形态的变化。方法：24个离体牙随机分为3组,组为对照组,B组采用Longhurst釉质微打磨,即35%磷酸酸蚀,然后钨钢车针打磨,组采用ACLonghurst法打磨后家庭漂白4周,通过扫描电镜观察釉质表面形态的变化。结果：Longhurst法釉质微打磨后牙釉质表层釉柱结构消失,继续漂白4周,釉质不规则孔隙增多。结论：Longhurst是釉质表面的机械磨除,而随后的漂白可造成釉质的脱矿表现。     

应用Nd:YAG激光防龋的研究进展

Nd:YAG激光因能改变牙齿硬组织的表面形态、改变釉质和牙本质的晶体结构、促进牙齿硬组织对氟的吸收而被应用于预防龋病。本文着重就Nd:YAG激光对牙体硬组织的作用，对牙齿硬组织吸氟能力的影响以及对牙髓的影响等方面的研究进展作一综述。     

Histological aspects of tooth bleaching technics

The chemical principles of tooth bleaching are detailed in order to analyze scanning microscopy data obtained following internal and external bleaching tooth bleaching appears harmless to the enamel structure providing no etching is applied prior to bleaching. Previous enamel undermining appears to increase the porosity along preexisting cracks. Internal bleaching gives way to enamel and dentinal demineralization, which is of particular importance at the dento enamel junction. The biological effects of bleaching on dental hard tissues must be viewed in light of the clinical indications for these procedures.     

不同表面处理方法对牙本质表面形貌及粗糙度影响的原子力显微镜研究

目的采用原子力显微镜(atomic force microscopy AFM)研究不同处理方法对牙本质表面形貌及粗糙度的影响,为牙本质表面处理方式的临床应用提供理论依据。方法将离体前磨牙牙本质表面分为三组,分别采用磷酸处理,磷酸/次氯酸钠处理,未做任何处理的表面作为空白对照组,在接触模式下(contact mode),采用原子力显微镜观察表面形貌,应用AFM的自带软件测量其表面粗糙度,粗糙度结果经t检验对各组进行统计学分析。结果牙本质表面经过磷酸处理后,牙本质小管变大,粗糙度增加,经过磷酸/次氯酸钠处理后,牙本质表面呈现均一的微观表面,粗糙度显著增加,各组之间均存在统计学差异。结论磷酸处理后能通过牙本质小管的脱矿来增加牙本质表面的粗糙度,而磷酸/次氯酸钠处理后,能在牙本质表面形成均匀的孔隙,极大地增加了表面粗糙度,后者为指导临床中的牙本质表面处理方式提供了新思路。     

Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition

OBJECTIVE: This study examined the effects of hydrogen peroxide tooth bleaching strips on the surface hardness and morphology of enamel and the ultrastructure and chemical composition of enamel and dentin in vitro. METHODOLOGY: Sound human molars were ground and polished to prepare a uniform substrate for bleaching treatments. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching strips, which utilize hydrogen peroxide in a gel as the in situ bleaching source at 6.0 and 6.5% concentrations of H2O2. Control treatments included an untreated group. Crest Whitestrips bleaching included treatment exposures simulating 2x the recommended clinical exposures (28 hours bleaching). Surface color measurements were taken prior to and following bleaching to ensure tooth bleaching activity. The effects of bleach on physical properties of enamel were assessed with microhardness measures. Ultrastructural effects were classified by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth microchemical composition was studied in different tooth regions by coincident assessment of Raman spectroscopic signature. RESULTS: Color assessments confirmed significant ex vivo tooth bleaching by Whitestrips. Surface microhardness and SEM measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ, and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the microchemical composition of enamel and dentin. CONCLUSION: These results confirm that tooth bleaching with hydrogen peroxide whitening strips does not produce changes in surface/subsurface histomorphology or in surface microhardness and ultrastructure of treated teeth. In addition, for the first time, these results confirm the safety of hydrogen peroxide bleaching strips to tooth microchemical composition as measured by Raman spectroscopy.     

Effects of elevated hydrogen peroxide 'strip' bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes

OBJECTIVES: This study examined the effects of elevated concentration hydrogen peroxide tooth whitening treatments on tooth surface and subsurface integrity. METHODS: Sound human molars were ground and polished to prepare an uniform substrate for bleaching treatments. A cycling treatment included alternating ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching was carried out with prototype bleaching strips containing hydrogen peroxide gel at 13% and 16% concentrations. A non-bleached group was used as a control. Treatments included 28h of total bleaching exposure in vitro. Surface color was measured prior to and following bleaching. Effects of bleach on physical properties of tooth surfaces were assessed by microhardness measures on enamel. Ultrastructural effects were examined by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth micro-chemical composition were studied by Raman spectroscopy combined with CLSM technique. RESULTS: Color assessments confirmed significant ex vivo tooth bleaching. Surface microhardness and VP-SEM (variable pressure SEM) measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the micro-chemical composition of enamel and dentin. Significant effects of bleaching were seen in reducing background luminescence of Raman spectra obtained from enamel and dentin. CONCLUSIONS: These results confirm that hydrogen peroxide whitening strips do not produce changes in surface/subsurface histomorphology, surface microhardness and micro-chemical composition of teeth. Effects of bleaches on tooth luminescence recorded in micro-Raman spectroscopy may serve as an internal signature to bleaching effects and warrant further study.     

Tooth brushing, tooth wear and dentine hypersensitivity--are they associated?

Evidence suggests that patients suffer the painful symptoms of dentine hypersensitivity when dentine is exposed and the dentinal tubule system is opened to the oral cavity to allow stimuli to trigger a neural response in the pulp via a hydrodynamic mechanism. The processes needed to localise lesions of dentine hypersensitivity include loss of enamel and/or gingival recession. Whilst tooth brushing with or without toothpaste appears to cause minimal wear to enamel (in the absence of acids), circumstantial evidence implicates tooth brushing with gingival recession and exposure of dentine. Other tooth wear processes, notably attrition and acid erosion, cause loss of enamel and can expose dentine. Therefore, sensitivity may result. How lesions of dentine hypersensitivity are initiated is a matter of conjecture and based on extrapolating data from studies, mainly in vitro, to effect in vivo. Again, this circumstantial type of evidence suggests that abrasion by some toothpastes and erosion by dietary acid could open the tubule system. Little is known about the actual effect of de-sensitising toothpastes on lesions of dentine hypersensitivity even though they are formulated to either occlude dentinal tubules or block the neural response in the pulp. Clinical studies have produced contradictory findings for the efficacy of products and there have been extremely few evidence-based reviews. In conclusion, available evidence supports a probable link of tooth brushing, with or without toothpaste and an acidic diet, to both tooth wear and dentine hypersensitivity, and also suggests that dentine hypersensitivity is a tooth wear phenomenon. Although there is a need for more direct clinical and scientific evidence for these associations, it is recommended that they be taken into consideration when planning management strategies for the dentine hypersensitivity sufferer.     

SEM study on the dentin and cementum of oreodont teeth

An SEM study on the dental hard tissue was conducted on the canines and molars removed from a fossil oreodont. The orthodentin was densely distributed with dentinal tubules measuring 2.2 microns in diameter; the tubules were filled with their related odontoblastic processes. They coursed in a parabolic fashion from the pulpal aspect towards the tooth surface. There were many fine lateral offshoots that branched from the tubules, such that the mantle dentin measuring 50 microns in thickness was mostly distributed with these terminal branches measuring 0.7 micron in diameter. However, they did not intrude into the enamel to form spindles and rods. SEM study indicated that the uneven surface of the tubular wall was due to a crisscross of the underneath dentinal matricial fibers, and the peritubular dentin was not observed. The superficial circumpulpal dentin was distributed with interglobular dentin, while the radicular dentin beneath the cementum was additionally distributed with a granular layer. We also observed concentric lamellae corresponding to incremental lines in the dentin, as well as a flat wavy dentinoenamel junction. We noticed the radicular dentin was covered with an acellular cementum except at the apical portion, where it was paved with cellular cementum.     

Bonding of restorative materials to dentine: the present status in Japan

Monomers which promote adhesion not only to enamel but also to dentine have been prepared. They have both hydrophilic and hydrophobic groups. The monomers are 2-hydroxy-3-beta-naphthoxypropyl methacrylate, 2-methacryloxyethyl phenyl hydrogen phosphoric acid and 4-methacryloxyethyl trimellitate anhydride. Chemical reaction between monomers and tooth substrates did not lead to adhesion. Cleaning of the ground tooth surface to remove the smeared layer with aqueous 10 per cent citric acid and 3 per cent ferric chloride solution prior to adhesion is recommended. Then, the lipophilic monomers will promote the inter-penetration of monomers into the hard tissues. The infiltrated methacrylates polymerize there and good adhesion takes place. The layer has good resistance against acid and is, in effect, a resin reinforced dentine and enamel as demonstrated by SEM and TEM. The tensile adhesive strength to the cleaned dentine was 18 MN/m2 and to the enamel 14 MN/m2. On the other hand, the value was reduced to 6 MN/m2 when the dentine had been etched by phosphoric acid or citric acid. The ferric chloride added to the citric acid protected dentinal collagen during demineralization. However, the ferric chloride provided ineffective protection against an acid as strong as phosphoric acid. The high bond strength was not dependent upon interlocking at the dentinal tubules as had been considered previously. The resin reinforced dentine and enamel is a hybrid of natural tissue and artificial material and is valuable in the prevention of secondary caries after restoration.     

Tooth brushing,tooth wear and dentine hypersensitivity — are they associated?

Evidence suggests that patients suffer the painful symptoms of dentine hypersensitivity when dentine is exposed and the dentinal tubule system is opened to the oral cavity to allow stimuli to trigger a neural response in the pulp via a hydrodynamic mechanism. The processes needed to localise lesions of dentine hypersensitivity include loss of enamel and/or gingival recession. Whilst tooth brushing with or without toothpaste appears to cause minimal wear to enamel (in the absence of acids), circumstantial evidence implicates tooth brushing with gingival recession and exposure of dentine. Other tooth wear processes notably attrition and acid erosion cause loss of enamel and can expose dentine. Therefore sensitivity may result. How lesions of dentine hypersensitivity are initiated is a matter of conjecture and based on extrapolating data from studies, mainly in vitro, to affect in vivo. Again this circumstantial type of evidence suggests that abrasion by some toothpastes and erosion by dietary acid could open the tubule system. Little is known about the actual effect of desensitising toothpastes on lesions of dentine hypersensitivity even though they are formulated to either occlude dentinal tubules or block the neural response in the pulp. Clinical studies have produced contradictory findings for the efficacy of products and there have been extremely few evidence based reviews. In conclusion, available evidence supports a probable link of tooth brushing, with or without toothpaste and an acidic diet to both tooth wear and dentine hypersensitivity, and suggests also that dentine hypersensitivity is a tooth wear phenomenon. Although there is a need for more direct clinical and scientific evidence for these associations, it is recommended that they be taken into consideration when planning management strategies for the dentine hypersensitivity sufferer.     

Er:YAG激光处理对牙本质与树脂粘结强度的影响

目的:探讨Er:YAG激光处理对牙本质表面性能及树脂粘结强度的影响。方法:选取30颗无龋坏、无修复体的人离体磨牙,用高速涡轮手机在流水冲洗下磨除釉质层。每个牙冠以髓腔为中心沿近远中向切开成颊/舌两部分,最终选取50个样件,按不同的表面处理方法随机分为5组(A~E组),每组10个样件。每组2个样件扫描电镜观察,其余8个样件分别在处理后的牙本质表面粘结光固化复合树脂,进行剪切强度测试。结果:C组最高,为(7.11±1.73) MPa,E组次之,E组与A、C、D组无统计学差异, B组较低,其中B组与C、D、E组均有统计学差异。扫描电镜观察:酸蚀组可见部分牙本质小管口开放,管径未增大;管周牙本质与管间牙本质界限不明显。激光+酸蚀组可见牙本质表面清沽,牙本质小管开放,周围白晕环绕。激光组可见牙本质表面清洁、粗糙,无玷污层,呈片状、蜂窝状外观,管周牙本质与管间牙本质界限清晰。结论:Er:YAG激光处理能增加牙本质与树脂的剪切粘结强度,但是合适的能量参数有待进一步研究。