如何测评牙本质过敏的症状(三)

如何测评牙本质过敏的症状（三）南京医科大学口腔医学系孙卫斌４测评刺激方法：４．１机械刺激：机械刺激，最常用的就是用牙科探针作探查，是检查牙本质过敏最常用的方法。如前所述，目前认为，牙本质过敏的机理是通过牙本质小管的小管内液流量增加。那末探诊如何使牙体...     

上颌第一前磨牙髓腔壁扫描电镜观测及其临床意义

目的：揭示在髓腔壁的微细形态学规律，为根管治疗术以及理解牙本质过敏现象提供应用形态学基础。方法：首先采用扫描电镜对２５颗４的髓腔壁进行系统观测，并分区定点摄影，然后对扫描电镜照片进行形态测量。结果：①牙本质小管口分为４型，即圆形、卵圆形、长条形和不规则形。②从髓室自根尖方向，牙本质小管口的直径、密度和相对面积均逐渐减小。③不规则性继发性牙本质最多见于根尖１／３，其次是根中１／３。结论：①牙本质小管口的形态与牙本质小管的走向及其在钙球上的开口的形态与牙本质小管的走向及其在钙球上的开口部位有相关关系。②牙本质小管口的相对面积较单纯的牙本质小管口的直径和密度更能全面地反映不同部位髓腔壁的特征。③不规则性继发性牙本质的出现属于生理现象而并非病理变化。     

牙本质敏感症的治疗:光固化树脂村对牙本质小管的封闭效果

牙本质敏感症是一种很常见的临床症状,其机制尚不甚明了,至今还没有建立一种完全可靠的治疗方法. 作者曾用新的活检技术,采得牙本质标本,进行扫描电镜和透射电镜观察,发现:过敏区的许多牙本质小管口都是开放的,但在同一暴露根面非敏感区的牙本质小管则为钙化物所封闭。因此,作者用封闭牙本质小管的方法治疗牙本质敏感症。     

纳米羟基磷灰石的制备及其对牙本质小管封闭效果的初步观察

目的 通过合成纳米羟基磷灰石(hydroxyapatite,HA)以及体外实验观察其对牙本质小管的封闭效果,为纳米HA的临床应用提供依据.方法 采用磷酸氢二铵[(NH4)2HPO4]和硝酸钙[Ca(NO3)2]合成纳米HA,扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、傅里叶变换红外光谱计(Fourier transform infrared spectrometer,FTIR)和X射线衍射仪(X-ray diffractometer,XRD)检测纳米HA.选取8颗健康第三磨牙制备24片牙本质薄片,按随机数字表分为酪蛋白磷酸肽钙磷复合体(casein phosphopeptideamorphous calcium phosphate,CPP-ACP)组、纳米HA组及空白对照组,每组8片;空白对照组不做处理,CPP-ACP组和纳米HA组每天分别用CPP-ACP和纳米HA处理牙本质薄片2次,7d后SEM观察牙本质表面.结果 经SEM、TEM、FTIR和XRD检测,证实本项实验制备的HA为纳米HA;SEM观察纳米HA对牙本质小管的封闭效果明显高于CPP-ACP组和窄白对照组.结论 在体外条件下,与CPP-ACP相比,纳米HA可更有效地封闭暴露的牙本质小管.     

根面牙本质过敏区与非过敏区显微形貌研究

应用一种新研制的牙体微量定位取样钻，在根面牙本质过敏区及非过敏区钻取微量牙本质标本。扫描电镜观察发现，在过敏区根面，多数牙本质小管开放，其断面观小管内壁管壁光滑；而非过敏区根面，许多牙本质小管开口堵塞，断面观小管内有许多粒状结晶。电镜照片经计算机辅助图像处理显示，过敏区牙本质小管管径面积平均为４．０２９±０．８８３μｍ２，而非过敏区牙本质小管管径面积为２．２６５±１．４７１μｍ２。两组间有非常显著性差异。本研究提示根面牙本质过敏具有稳定的显微形貌特征     

Er,Cr:YSGG激光和酸蚀处理牙本质表面后的扫描电镜观察

目的 本文通过电镜观察，研究不同预备方法处理牙本质后表面形态的改变及树脂-牙本质界面形态的差别。方法 用10颗拔除的第三磨牙制作牙本质片，每个牙本质片预备三个窝洞，分别用传统方法加酸蚀预备，Er，Cr：YSGG激光预备及激光加酸蚀预备。将10个牙本质片分为A、B两组，A组在电镜下观察牙本质表面形态改变；B组用流动树脂充填，暴露树脂-牙本质界面，样本经处理后在电镜下观察比较。结果 A组：传统方法预备后牙本质表面可见开放的牙本质小管口；激光预备后开放的牙本质小管口呈现火山口样；激光加酸蚀处理后的牙本质小管周围呈现白晕。B组：传统预备方法的树脂一牙本质界面可见混合层，圆锥型树脂突和侧枝连接的形成；单纯激光预备后界面没有混合层的形成，形成的树脂突呈圆柱型，较长并且细密；激光加酸蚀处理后界面可见少量混合层形成，树脂突圆柱型，粗、长且有少量侧枝连接。结论 Er，Cr：YSGG激光加酸蚀处理后，开放的牙本质小管周围可见来完全脱矿的管周牙本质．树脂一牙本质界面可见混合层和粗长的圆柱形树脂突。     

仿生矿化纳米磷酸钙对牙本质小管封闭性能的评价

目的 制备仿生矿化的纳米磷酸钙,并探讨其对牙本质小管的封闭性能。方法 采用DMEM仿生矿化策略制备无定形磷酸钙材料(DMEM based amorphous calcium phosphate,DACP),运用透射电子显微镜(TEM)、傅里叶变换红外光谱扫描(FTIR)等检测观察其理化表征。选择口腔上皮角质形成细胞(HOK)和牙髓细胞(DPC)分别与材料共培养24 h后,CCK-8法评估材料的生物相容性。收集完整无龋的牙齿制备牙本质片,用DACP材料悬液均匀涂抹牙本质片,设置阳性对照NovaMin组和空白对照组,分别处理1、7 d后扫描电子显微镜(SEM)评估牙本质片的表面和截面封闭效果。结果 TEM显示DACP为均匀球形无定形纳米颗粒,随矿化时间的延长粒径有所增加。CCK-8结果显示HOK和DPC在25、50、100、200 μg/mL DACP下细胞活力均较好,提示材料有较好的生物相容性。牙本质片被处理1 d后DACP组牙本质小管大部分封闭;被处理7 d后DACP组牙本质小管表面呈现完全封闭的状态,且牙本质片截面可见DACP可渗入小管内。结论 运用DMEM仿生矿化策略制备的纳米磷酸钙具有较好的生物相容性和牙本质小管封闭作用,有望成为一种新的脱敏材料。     

髓腔内使用牙本质小管阻塞剂封闭牙本质小管的实验研究

目的 比较髓腔内使用两种牙本质小管阻塞剂阻塞牙本质小管的效果。方法 选择90颗离体单根管牙经常规根管清理成形后,随机分为3组(其中1组为对照组),两实验组在髓腔内使用草酸钾或光固化粘接剂,用染料渗透法观察比较染料浸入牙本质的情况。结果 两实验组与对照组相比其染料浸入牙本质的情况有极为显著性差异(P<0.01)。结论 在髓腔内使用牙本质小管阻塞剂可以有效地阻止染料渗入牙体。     

治疗牙本质过敏的新型脱敏剂

牙本质过敏(dentine hypersensitivity),是由于温度变化、机械磨损、渗透压变化和化学刺激等因素作用于牙齿而发生的一过性、以疼痛感为主的临床症状.多数学者认为:牙本质小管内的液体流动,是导致该症状的主要原因.即外界刺激促使牙本质小管内的液体流动,间接使其中的游离神经末梢兴奋,传入冲动,产生痛觉.另外,分布于牙本质小管内的各类化学物质、牙齿的电流变化,也可直接刺激牙髓神经纤维,从而在牙齿处于特定的状态时(如牙本质暴露,牙髓兴奋性亢进等),出现牙本质过敏的症状.根据液体动力学说,对牙本质过敏的有效治疗是封闭牙本质小管,以减少或避免牙本质内的液体流动.本文就极固宁对牙本质过敏的治疗进行观察报告如下.     

脱敏剂MS-COAT阻塞牙本质小管的电镜观察分析

[摘要] 目的 通过场发射扫描电镜观察脱敏剂MS-COAT对牙本质小管的堵塞效果,分析其对于治疗牙本质过敏症的机理。方法 制作牙本质小管暴露模型,并通过扫描电镜观察使用MS-COAT脱敏剂组和空白对照组的牙本质小管表面情况。同时通过能谱分析拍摄扫描电镜图片,对牙本质小管堵塞物成分进行分析。结果 MS-COAT处理组横断面牙本质小管大部分被晶体类物质封闭,纵断面可见牙本质小管内有堵塞物。对堵塞物及牙本质成分进行能谱分析:堵塞物主要成分为钙和磷,牙本质含钙磷量97.44%,堵塞物含钙磷量较低结论 MS-COAT脱敏剂能有效封闭牙本质小管表面和内部,具有较好的脱敏的作用。     

Tricalcium silicate induced mineralization for occlusion of dentinal tubules

Background: The aim of this study was to evaluate the dentinal tubule occluding ability of tricalcium silicate (Ca₃SiO₅ or C₃S) in vitro. Methods: Dentine discs were prepared from extracted caries‐free human third molars and etched with 0.02 M citric acid (pH 4) for 3 minutes in order to produce patent dentinal tubules. Tricalcium silicate pastes of different viscosities were applied to the surface of the dentine specimens for 3 minutes and then removed with a swab followed by deionized water rinse. The dentine specimens were immersed in artificial saliva for 7 days. The tubule occlusion, sealing depth and chemical composition of the dentine specimens and bonding force between the dentine matrix and mineralized layer were evaluated by scanning electron microscopy, energy dispersion X‐ray spectroscopy, X‐ray diffraction analysis and a nanoscratch test. Results: A homogeneous layer of mineral crystals was precipitated onto the dentine surface and caused significant occlusion of the dentinal tubules. The dentine permeability and sealing depth of the C₃S increased with the decrease of viscosity of the paste. With a proper viscosity of C₃S pastes, the interface between the mineralized layer and the dentine matrix bonded well. Conclusions: This study suggests that C₃S may be an effective agent for the treatment of dentine hypersensitivity.     

Effects of plaque control on the patency and occlusion of dentine tubules in situ

To elucidate the nature of dentine hypersensitivity, the effects of plaque control on the patency and occlusion of dentinal tubules were investigated systematically in situ using human dentine slabs embedded in partial dentures. The dentine slabs were divided into three groups. In group I, the dentine slabs were kept in an oral cavity without plaque control. In group II, plaque was removed mechanically by brushing. Plaque control was carried out chemically using chlorhexidine in group III. After being kept in the oral cavities for 1, 2 and 3 weeks, the slabs were removed from the partial denture, followed by SEM observation to determine the morphological changes of the dentinal tubules. When no attempt was made to remove plaque, the diameter of tubule orifices increased to 390% of the original values within 3 weeks. In contrast, dentinal tubules were found to be occluded, i.e. the tubule orifices became <20% of the original value within 1 week when plaque control efforts were made, using either method of plaque control. We conclude that plaque control plays one of the key roles in the patency versus occlusion of dentinal tubules, and thus in the aetiology and natural reparative process of dentine hypersensitivity.     

Calcium silicate coating derived from Portland cement as treatment for hypersensitive dentine

OBJECTIVES: To evaluate the in vitro effectiveness on dentine permeability and dentine morphology of a calcium silicate treatment based on Portland cement (DSC). METHODS: The experimental treatment consisted of a calcium silicate paste based on Portland cement that was applied on dentine surface for 3 min. A professional re-mineralizing treatment (GC Tooth Mousse), two in office desensitizing agents (D/Sense Crystal, and By Sealant) and a commercial toothpaste Dentosan S were studied as comparison materials. All materials were applied accordingly with manufacturer directions on wet dentine. The quantitative changes in the hydraulic conductance i.e., permeability through tubules of dentine discs samples produced by treatment were quantified in vitro using a hydrostatic device working at 6.9 kPa. SEM/EDX analyses of dentine were carried out to obtain qualitative information on dentine morphology and surface deposits and to study their relationship with the hydraulic conductance. After treatment, each dentine sample was immersed in artificial saliva and permeability re-evaluated. Finally, each sample was exposed to 0.02 M citric acid solution and the final permeability was assessed. RESULTS: The experimental treatment and both oxalate-based products (D/Sense Crystal and By Sealant) significantly decreased dentine permeability and created crystals and precipitates on the dentine surface that reduced the diameter of dentinal tubules. Artificial saliva immersion and citric acid challenge increased dentine permeability and partially modified the treated surfaces. Dentosan S and GC Tooth Mousse treatments partially reduced dentine permeability and created small amount of precipitates that were removed by saliva immersion and citric acid exposure. EDX revealed the presence of calcium-rich layer after DSC experimental treatment. CONCLUSIONS: The application of the experimental calcium silicate paste and oxalate-based treatments was determined to be effective on dentine permeability reduction and tubules occlusion. The clinical use as desensitizing agent of materials derived from Portland cement as desensitizing agent should be considered for dentine hypersensitivity treatment.     

Dentine hypersensitivity

Based on the hydrodynamic theory for stimulus transmission across dentine, it would be logical to conclude that teeth exhibiting the clinical symptoms referred to as dentine hypersensitivity should have dentinal tubules open at the root surface and patent to the pulp. With the exception of studies on cut dentine, there is little direct evidence to support this conclusion. In this study, caries-free teeth with exposed cervical root areas scheduled for extraction which were classified as non-sensitive or hypersensitive after suitable stimulation were examined by scanning electron microscopy. Hypersensitive teeth showed highly significantly increased numbers of tubules per unit area (approximately 8 X) compared with non-sensitive teeth. Tubule diameters were significantly wider (approximately 2 X) in hypersensitive compared to non-sensitive teeth. The number of teeth showing the penetration of methylene blue through the zone of exposed cervical dentine was larger and the depth of penetration greater in hypersensitive teeth compared to non-sensitive teeth. The results provide further evidence that stimulus transmission across dentine in hypersensitive teeth is mediated by a hydrodynamic mechanism. An understanding of factors which open dentinal tubules would seem important if attempts to prevent or treat dentine hypersensitivity are to be successful.     

Dentine hypersensitivity

Studies of extracted teeth have shown that teeth exhibiting dentine hypersensitivity have larger numbers of widened dentinal tubules at the dentine surface compared to non-sensitive teeth. Many compounds used in the treatment of dentine hypersensitivity are thought to achieve therapeutic benefit by tubule occlusion, but there has been almost no attempt to prove such action in vivo. These studies systematically determined whether the dentine surface could be evaluated non-invasively, by a scanning electron microscopic replica technique. Employing a silicone rubber impression method in vitro, the surface detail of dentine could be accurately replicated, with surface scratches, tubules and intratubular structures on the original reproduced on the replica. With attention to method, similar accuracy was achieved in vivo, particularly when tubules were open on the dentine surfaces of the original. The method would appear useful for the study of the dentine surface in cases of dentine hypersensitivity and could prove the first objective method of studying the effects of treatment agents used in the treatment of this painful condition.     

Diffusive transport within dentinal tubules: an X-ray microtomographic study

The hydrodynamic theory of dentine hypersensitivity proposes that external stimuli cause dentinal fluid movement within dentinal tubules thereby triggering mechanosensitive nerves and eliciting a pain response. The aim of this study was to employ X-ray microtomography (XMT) to monitor diffusion of caesium acetate through dentine to investigate the extent to which transport occurs within the primary tubules compared to that through branched microtubules believed to run perpendicular to the direction of the primary dentinal tubules. 2.0-mm thick coronal dentine disks masked to leave half of the upper surface exposed were imaged by XMT, initially in water, which was then replaced with an aqueous solution of 0.50 mol l(-1) caesium acetate. Further XMT images were acquired after 1 and 6 days immersion. The XMT images were used to measure the change in the X-ray linear attenuation coefficient resulting from caesium acetate ingress into dentine. There was clearly considerable ingress of caesium acetate into the dentine lying below the exposed surface, but considerably less beneath the sealed surface, suggesting that diffusive transport occurs predominantly in the direction of the primary dentinal tubules, with no significant lateral transport. Primary tubules are clearly the dominant transmission route for triggering the mechanosensitive nerves present at the dentine-pulp interface, and for delivery of nerve desensitising agents.     

Dentine hypersensitivity - A review

The exposure of cervical dentine has a multifactorial aetiology and pain may frequently be elicited by a number of stimuli. Management of the condition, dentine hypersensitivity, tends to be empirical because of the lack of knowledge concerning the mechanism of pain transmission through dentine. The pulpal changes associated with the condition and any modulating effect on symptoms are by no means clearly established. Evidence suggests that exposed dentine which is sensitive exhibits patent tubules. The question of how pain is initiated across the dentine has received considerable attention but still remains somewhat debatable. The literature reviewed indicates that, at most, nerve fibres only penetrate a limited distance along some dentinal tubules. The theories that either the odontoblasts and their processes act as dentinal receptors or the nerves in the pulp are the pain receptors, are discussed. Evidence for the stimulation of pulp nerve fibres by a hydrodynamic mechanism would appear the most likely mechanism. Nevertheless, whichever theory proves to be correct, occlusion of dentinal tubules would appear an essential prerequisite for an effective desensitising agent.     

Dentine hypersensitivity: the effects of brushing desensitizing toothpastes, their solid and liquid phases, and detergents on dentine and acrylic: studies in vitro

Dentine exhibiting symptoms of dentine hypersensitivity has tubules open at the dentine surface and patent to the pulp. The mechanisms whereby dentinal tubules are exposed is ill understood but probably involves a variety of abrasive and/or erosive agents. This study in vitro examined the quantitative and qualitative effects of toothpastes, their solid and liquid phases and detergents on dentine and acrylic. Abrasion of dentine and acrylic were measured by surfometry. Morphological changes to dentine were assessed by scanning electron microscopy. Abrasion of dentine and acrylic by toothpastes increased with increasing brushstrokes with marked differences in the extent of abrasion between different pastes. Brushing dentine with water or detergents produced progressive abrasion but which appeared to plateau around 2 μm loss. Water and detergents produced minimal effects on acrylic. At 5000 strokes dentine abrasion by solid phases was less than the parent toothpastes but the ranking order of abrasivity was the same as the parent toothpastes. Loss of dentine produced by liquid phases was minimal and in the order of 1–2 μm. Observationally, all toothpastes removed at least the dentine smear layer to expose many tubules; with one desensitizing product leaving a particulate deposit occluding most tubules. The solid phases of the toothpaste produced identical morphological changes to the parent paste. The liquid phases and detergents all exposed dentinal tubules by 5000 strokes. Water had little or no effect on the dentine smear layer. It is concluded that toothpastes, solid phase, liquid phase and detergents have the potential to abrade or erode dentine to a variable degree and result in tubule exposure. The effects of the liquid phases and detergents appear limited to the removal of the smear layer. Such detrimental effects seen in vitro could have relevance to the aetiology and management of dentine hypersensitivity. Toothpaste formulations which despite exposing tubules have ingredients capable of occluding tubules may be an area of development for such products.     

牙本质小管封闭治疗牙本质过敏症的机制和效果

牙本质过敏症是由于釉质的完整性受到破坏,造成牙本质小管暴露,从而使牙齿对温度、化学物质和机械刺激等因素敏感的一种临床病症。其治疗的主要方法是封闭暴露的牙本质小管,降低牙本质小管的通透性。封闭方法按机制可分为原位沉积法、氟诱导矿化法、纳米粒子填塞法、粘接覆盖法和激光熔融法等。对于这些封闭方法实验室常用的效果评价手段主要包括扫描电镜观察和牙本质渗透性检测。本文就近年来封闭牙本质小管不同方法的内在机制和效果作一综述。