牙本质涎蛋白在牙齿发育、牙本质疾病中的表达和作用

牙本质基质是由胶原和非胶原蛋白组成,其中非胶原蛋白又包含了一组牙本质特异性蛋白,它们在牙胚发育,矿化过程中起重要作用.该文就牙本质特异性蛋白中的牙本质涎蛋白在牙齿发育和牙本质疾病中的表达和作用作一综述.     

牙本质基质蛋白-1的研究进展

牙本质基质蛋白-1是牙发育过程中一种非常重要的非胶原性基质蛋白,对牙本质的形成和矿化起着重要的作用,但其具体的作用机制有待于进一步的研究.下面就牙本质基质蛋白-1的表达定位、基因结构、生物学功能以及表达调控因素作一综述.     

牙本质涎磷蛋白的研究进展

牙本质涎磷蛋白及其蛋白剪切产物—牙本质涎蛋白和牙本质磷蛋白是在牙本质发育、矿化中起重要作用的非胶原蛋白.关于牙本质涎磷蛋白的结构、功能、表达以及翻译后修饰等均有大量的研究,使之对牙本质涎磷蛋白的认识不断深入.本文就近年来关于牙本质涎磷蛋白的研究现状作一综述.     

组织工程化牙本质种子细胞的研究进展

成牙本质细胞是牙齿发育的重要细胞,寻找形成成牙本质细胞的种子细胞,获得稳定可靠的细胞来源是组织工程化牙本质研制的先决条件.牙胚、牙乳头、牙髓,甚至脱落的乳牙牙髓里都存在形成牙齿的前体细胞.本文就近年来组织工程化牙本质种子细胞的研究现状进行了综述.     

反应性牙本质研究概况

反应性牙本质是牙髓受到适当刺激后,由原始的成牙本质细胞所分泌并沉积在管内及牙髓和牙本质交界处的一种第三期牙本质。它可能是一种正常的生理反应,也可以在病理状态下出现。其形态结构有多种表现形式。目前对反应性牙本质形成的研究正日益受到学术界关注,焦点集中于诱导反应性牙本质形成的分子学机制,旨在为研制新的生物活性修复材料提供科学依据。     

牙髓干细胞与牙本质再生相关性的研究进展

牙髓中存在具备自我更新和多向分化潜能的牙髓干细胞.这些细胞经诱导可向成牙本质细胞分化并形成牙本质样结构,有望成为牙本质再生的种子细胞.本文就牙髓干细胞的来源、生物学特性及其在牙本质再生中的应用作一综述.     

纤维粘连蛋白在牙本质形成中的作用

纤维粘连蛋白(fibronectin,Fn),是一种多功能高分子量糖蛋白,广泛存在于胞外基质中,在发育和损伤修复中调节细胞附着、移行和分化。近年来在牙齿发育和牙髓修复过程中,Fn在诱导成牙本质细胞及成牙本质细胞样细胞分化,促进牙本质形成过程中发挥重要的调控作用,本文就Fn在牙本质形成中的作用研究进展作一综述。     

牙本质痛与牙本质过敏的临床应对

正常感受状态下的牙本质痛作为机体防御反应,在牙本质暴露后,通常以原发病作为就诊原因,表现为一定强度的冷、热、酸、甜等刺激后,出现一过性、锐性酸痛.刺激性痛的程度不剧烈,在体征上可以看到牙本质暴露.治疗时以治疗源发病为主,不需用修复治疗的牙体缺损,可以考虑封闭牙本质小管,防止外界刺激损害牙髓神经.当牙本质感觉异常,出现牙本质过敏症时,患者的主诉症状多是刺激性疼痛.轻度的温度、化学、触及等刺激后,出现一过性、剧烈的、锐性的、酸软的疼痛,影响进食、刷牙.有些患者甚至出现精神心理方面的改变.查体时多有牙本质暴露,暴露面有极度敏感点、剧烈的刺激激发痛.治疗时,强调封闭牙本质小管的开口,减小牙本质小管的通透性,以隔绝外界刺激对牙髓神经的继续损伤;重视使用降低牙髓神经的敏感性的方法;不能忽视给与患者生活指导,防止再复发.注意咬合创伤以及咬合调整在牙本质过敏的发病、治疗、预防、防止再复发中的重要作用.     

牙本质生物矿化机制的研究

牙本质是牙齿中主要的矿化胞外基质，其晶体基本结构为羟磷灰石（HA），晶体中存在一种纳米粒子，参与牙本质初始晶体的形成。牙本质非胶原蛋白在HA成核及生长中起着重要作用。钙的转运在牙本质矿化过程中以跨细胞转运为主。     

正畸力对幼鼠牙本质中DSP表达的影响

目的:探讨正畸力对牙齿发育过程的牙本质中DSP表达的影响.方法:选取5周龄雄性SD大鼠,建立正畸牙齿移动模型.分别于加力后1、3、7、14、21 d处死动物,取含双侧上颌第一磨牙的上颌标本,制作石蜡切片,进行HE染色和DSP免疫组化染色.结果:牙冠部牙本质小管、前期牙本质、成牙本质细胞和牙根部成牙本质细胞DSP染色阳性.其中,牙尖部位的牙本质小管和前期牙本质呈强阳性染色,14 d时达到高峰,21 d时阳性染色有所减弱;根部成牙本质细胞在实验初期呈弱阳性染色,随时间的延长阳性染色逐渐增强.正常对照组DSP的表达明显弱于实验组.结论:对处于发育晚期的年轻恒牙施加适当的正畸力会促使成牙本质细胞进入活跃状态,牙本质中DSP表达上调,从而在一定程度上加速牙本质的形成及矿化.     

牙本质无机物在牙本质粘接过程中的作用

目的探讨牙本质无机物在牙本质粘接过程中的作用。方法采用几种不同的牙本质处理方法，测试分析了牙本质与４ＭＥＴＡ／ＭＭＡＴＢＢ树脂之间的抗张粘接强度（ｔｅｎｓｉｌｅｂｏｎｄｉｎｇｓｔｒｅｎｇｔｈ，ＴＢＳ）。结果选用１０％柠檬酸和３％三氯化铁组成的酸盐体系预处理液（ａｃｉｄｓａｌｔｐｒｅｔｒｅａｔｉｎｇｓｏｌｕｔｉｏｎｓｙｓｔｅｍ，ＡＰＳＳ）去除牙本质污染层，再用次氯酸钠溶解牙本质胶原。暴露牙本质无机物时，牙本质的抗张粘接强度为５９３ＭＰａ，明显高于用蒸馏水冲洗的对照组（３７１ＭＰａ）（Ｐ＜００５）。结论说明牙本质无机物在牙本质粘接过程中确实具有一定的作用     

Contraction stress in dentin adhesives bonded to dentin

Adhesives cured under constrained conditions develop contraction stresses. We hypothesized that, with dentin as a bonding substrate, the stress would reach a maximum, followed by a continuous decline. Stress development was determined with a tensilometer for two total-etch systems and two systems with self-etching primers. The adhesives were placed in a thin layer between a glass plate and a flat dentin surface pretreated with phosphoric acid or self-etching primer. After an initial maximum shortly after light-curing, the stress decreased dramatically for the total-etch systems (70%) and, to a lesser extent, for the adhesives with self-etching primers (30%). The greater stress decrease for the total-etch systems was ascribed to water and/or solvents released into the adhesives from the fully opened dentinal tubules by the pulling/sucking action of the contraction stress. This happened less with the adhesives with self-etching primers, where the tubules remained mainly closed.     

Nanoleakage of dentin adhesive systems bonded to Carisolv-treated dentin

The hybrid layer created in caries-affected dentin has not been fully elucidated and may influence bond durability. This study investigated the nanoleakage patterns of caries-affected dentin after excavation with Carisolv or conventional instruments treated with one of three adhesive systems. Flat occlusal dentin surfaces, including carious lesions, were prepared from extracted human molars and finished with wet 600-grit silicon carbide paper. Carious dentin was removed with Carisolv or round steel burs in conjunction with Caries Detector. PermaQuik, Single Bond or One-Up Bond F was bonded to the excavated dentin surfaces and adjacent flat occlusal surfaces and it was covered with Silux Plus resin-based composite. After 24-hour storage in 37 degrees C water, the bonded interfaces were polished to remove flash, and the surrounding tooth surfaces were coated with nail varnish. Specimens were immersed in 50% (w/v) silver nitrate solution for 24 hours, exposed to photo developing solution for eight hours, then sectioned longitudinally through the bonded, excavated dentin or "normal" dentin surfaces. The sectioned surfaces were polished, carbon coated and observed in a Field Emission-SEM using back scattered electrons. Silver deposition occurred along the base of the hybrid layer for all specimens. However, Single Bond showed a greater density of silver deposition in the caries-affected dentin compared with normal dentin. PermaQuik had a thicker hybrid layer in caries-affected dentin than normal dentin. One-Up Bond F exhibited a thin hybrid layer in normal dentin, but the hybrid layer was often difficult to detect in caries-affected dentin.     

Bond strengths of single-bottle dentin adhesives to caries-affected dentin

There is concern that some acidic conditioners may not be strong enough to adequately etch sclerotic or caries-affected dentin. The hypothesis that was tested was that there were no significant differences in the bond strengths of single-bottle bonding systems to normal or caries-affected dentin, regardless of the strength of the phosphoric-acid conditioner. Extracted teeth with coronal caries extending into mid-dentin were prepared by grinding the occlusal surface flat. This left a central region of caries-affected dentin surrounded by normal dentin. The One-Step bonding system was used to bond dentin following etching with 10 or 32% phosphoric acid. The Single Bond system was used after etching dentin with 10 or 35% phosphoric acid. After 24 hours in water, serial vertical sections were made through the bonded teeth to create slabs 0.7 mm thick. Each tooth yielded four to five slabs, some of which included normal dentin, while others included caries-affected dentin. Each slab was trimmed into an hourglass configuration to limit the test area to normal or caries-affected dentin. The results obtained with One-Step following etching with 10% phosphoric acid showed lower (P < 0.05) tensile bond strengths to caries-affected dentin compared to normal dentin (36.9 +/- 8.0 MPa vs 47.7 +/- 6.5 MPa, respectively). This difference disappeared when using 32% phosphoric acid (49.7 +/- 6.1 MPa vs 45.0 +/- 7.2 MPa, respectively). Bonds made to caries-affected dentin with Single Bond were always lower than bonds to normal dentin regardless of the strength of the phosphoric acid. Scanning electron microscopy of polished cross sections sequentially challenged with acid and NaOCl revealed loss of the middle of the hybrid layers created by either bonding system in caries-affected dentin etched with 10% phosphoric acid. It is clear that 32-35% phosphoric acid is required to adequately etch caries-affected dentin in order to produce high bond strengths and well-infiltrated demineralized dentin.     

Nanotube-modified dentin adhesive—Physicochemical and dentin bonding characterizations

Objective

The aim of this study was to investigate the effect of aluminosilicate clay nanotubes (Halloysite, HNT) incorporated into the adhesive resin of a commercially available three-step etch and rinse bonding system (Adper Scotchbond Multi-Purpose/SBMP) on dentin bond strength, as well as the effect on several key physicochemical properties of the modified adhesive.

Methods

Experimental adhesives were prepared by adding five distinct HNT amounts (5–30 wt.%) into the adhesive resin (w/v) of the SBMP dentin bonding system. Bond strength to human dentin, microhardness, and degree of conversion (DC) of the modified adhesives were assessed.

Results

From the shear bond strength data, it was determined that HNT incorporation at a concentration of 30 wt.% resulted in the highest bond strength to dentin that was statistically significant (p = 0.025) when compared to the control. Even though a significant increase in microhardness (p < 0.001) was seen for the 30 wt.% HNT-incorporated group, a significantly lower DC (p < 0.001) was recorded when compared to the control.

Significance

It was concluded that HNT can be incorporated up to 20 wt.% without jeopardizing important physicochemical properties of the adhesive. The modification of the SBMP dentin bonding agent with 20 wt.% HNT appears to hold great potential toward contributing to a durable dentin bond; not only from the possibility of strengthening the bond interface, but also due to HNT intrinsic capability of encapsulating therapeutic agents such as matrix metalloproteinase (MMP) inhibitors.     

Demineralized dentin, hydroxylapatite and dentin chips as apical plugs

Abstract Demineralized dentin, hydroxylapatite, or dentin chips were condensed into the apical 2 mm of canals with perforated apexes in 36 anterior teeth of 8 adult cynomolgus monkeys. The coronal sections of the canals were then obturated with gutta percha and Grossman's sealer. Twelve additional canals with perforated apexes were obturated 2 mm short of their radiographic apexes and served as controls. The amount of hard tissue formation and the degree of inflammation were evaluated after 3 and after 6 months. No differences were noted between the various materials after 3 months. However, after 6 months the samples with apical plugs of hydroxylapatite had more hard tissue formation and less inflammation than the others.