Resin-enamel bonds made with self-etching primers on ground enamel

Self-etching primer adhesives have recently been introduced to simplify bonding. However, the fundamental bonding mechanism of self-etching primers to enamel is not yet fully understood. This study aimed to investigate resin-enamel bonds of self-etching primer adhesives on ground enamel. Two self-etching primer adhesives (Clearfil Liner Bond 2 V and Clearfil SE Bond) were used in this study. A total-etch adhesive (One-Step) was used as a control. Resin-enamel beams were subjected to the microtensile bond test. Subsequently, the failure modes of all specimens were quantified using image analysis. Undemineralized and demineralized ultrathin sections of the resin-enamel bonded specimens were examined using transmission electron microscopy. The bond strengths of Clearfil SE Bond (39.8 +/- 11.9 MPa) and One-Step (46.2 +/- 12.7 MPa) were significantly greater than that of Clearfil Liner Bond 2V (30.4 +/- 6.2 MPa). Scanning electron microscopy of the fractured surfaces revealed the failure direction and weakest portion within each bond. Transmission electron microscopy showed a thin hybridized complex of resin in enamel produced by the self-etching primers without the usual micrometer-sized resin tags seen in resin-enamel bonds produced using the total-etch adhesive. The morphological features of the resin-enamel bonds produced by two self-etching primers tested were different from that created with the total-etch adhesive.     

Circumferential continuity of perikymata in human dental enamel investigated by scanning electron microscopy

Abstract – Theoretically the perikymata may represent one of two possible configurations: closed circles or continuous spirals. In the present study one randomly selected perikyma groove in one randomly selected tooth (the mandibular first premolar of a 12-yr-old girl) was tracked around the circumference of the crown in the scanning electron microscope. It was found that the perikymata geometrically represented closed circles. The possibility of methodologic error was excluded.     

Comparison of microshear bond strengths of four self-etching bonding systems to enamel using two test methods

BACKGROUND: Recent advances in enamel and dentine adhesive technology have resulted in the emergence of many new adhesive systems. Self-etching bonding systems do not require a separate etching step and the newest systems are the "all-in-one" systems which combine etching, priming and bonding into a single application. This study reports laboratory enamel microshear bond strengths of a self-etching priming and three all-in-one systems and also evaluates two different microshear bond test methods. METHODS: One hundred and nineteen enamel specimens were bonded (0.8 mm diameter) with either Clearfil Protect Bond (Kuraray), Xeno III (Dentsply), G Bond (GC) or One-Up Bond F (Tokuyama) using Palfique Estelite resin composite and stored in 37 degrees Celsius water for seven days. The microshear bond test method used either a blade or wire to apply the shear stress. Results were analysed with one-way ANOVA and post hoc (Tukey) multiple comparison analysis. RESULTS: Clearfil Protect Bond demonstrated higher and more consistent bond strengths than Xeno III, G Bond or One-Up Bond F. The wire method showed much greater reliability in results, with a coefficient of variation half that of the blade method. CONCLUSIONS: All-in-one adhesives seem to be less reliable than the two-step self-etching priming adhesive when bonding to enamel. Test method can significantly affect results in the microshear bond test method.     

Transmission electron microscope observations on enamel following silver methenamine staining

Abstract – Transmission electron microscope observations on porcine enamel and secretory ameloblasts showed that silver methenamine material was located inside secretory vesicles in secretory ameloblasts and along the enamel crystals inside immature enamel. It is concluded that silver methenamine is able to stain enamel proteins selectively inside these tissues.     

自酸蚀粘结剂牙本质粘结界面未封闭结构观察

目的观察并评价3种自酸蚀粘结剂(ClearfilTM SE Bond、AdperTM PromptTM、ONE-UP Bond F)牙本质粘结界面的未封闭结构。方法选取人体24颗无龋坏磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质粘结面玷污层。分别用3种自酸蚀粘结剂和1种全酸蚀粘结剂(对照组)按使用说明进行粘结处理。每颗牙齿标本垂直于粘结面切割出粘结试件,分别进行氨化硝酸银、三色法染色,观察牙本质粘结界面。结果在电镜和光学显微镜下均观察到3种自酸蚀粘结剂牙本质粘结界面混合层底部的纳米渗漏。结论自酸蚀粘结剂牙本质粘结界面中存在部分脱矿的未封闭牙本质结构。     

Scanning electron microscopy of fluorideinduced disturbances on the enamel surface of rat molars

Abstract — Rats were given a single high dose of fluoride at the age of 5 days and killed after 24 h, 10 or 15 days. The maxillary Erst molars were prepared for scanning electron microscopic examination. It was concluded that a single dose of fluoride, preferentially affecting ameloblasts with a high secretory activity, leads to the formation of subameloblastic cysts and enamel hypoplasias covered with granular deposits.     

冷冻电子显微镜观察人釉原蛋白的自组装

目的:采用冷冻电子显微镜(cryo TEM)体外观察人釉原蛋白的自组装过程,分析自组装各阶段蛋白的聚集状态及细微结构.方法:提取青少年下颌第三磨牙牙胚细胞总RNA,用RT-PCR获得人釉原蛋白基因全长,再与pMD19-T载体构建重组质粒,转入宿主菌E.coli Top10中诱导表达并纯化.冷冻电子显微镜观察pH值从3....     

髁突骨上组织扫描电镜和透射电镜的比较研究

目的比较髁突骨上组织在扫描电镜（ＳＥＭ）和透射电镜（ＴＥＭ）下的不同表现特点。方法３只成年健康家兔左侧髁突断裂后用ＳＥＭ的方法观察断面的结构,右侧做常规ＴＥＭ检查。结果ＳＥＭ发现,髁突软骨细胞仪表面呈蜂窝样的球体,胞内有多个空泡存在：钙化的软骨细胞这种表面形态消失,不规则地皱缩。ＴＥＭ下,软骨细胞似透明软骨细胞的典型形态,有短小突起,周围有半透明的薄带。钙化的软骨细胞内细胞器明显减少,部分有坏死的表现。结论ＳＥＭ观察到的髁突软骨细胞表面特征可反映细胞内部的结构和变化。     

自酸蚀黏结剂的牙本质黏结界面纳米渗漏观察

目的观察并评价3种自酸蚀黏结剂(ClearfilTMSEBond、AdperTMPromptTM、PANAVIATMF)黏结处理后的牙本质纳米渗漏。方法选取9颗无龋坏人磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质黏结面玷污层。分别用3种自酸蚀黏结剂按使用说明进行黏结处理。每颗牙齿垂直于黏结面切割出5个0.9mm厚黏结试件,避光贮存于氨化硝酸银溶液中24h,在透射电镜(TEM)下观察牙本质黏结界面纳米渗漏。结果3种自酸蚀黏结剂试件牙本质黏结界面混合层的底部在TEM下均观察到排列规则的银粒子渗漏。结论自酸蚀牙本质黏结界面下可能存在未完全封闭的牙本质脱矿层,存在纳米渗漏。     

Uncoated specimen of human enamel obeerved in the scanning electron microscope

Abstract – A1-mm-thick section of human premolar was acid etched and observed uncoated in the SEM at accelerating voltages of 3, 5, 10 and 15 k v . Prisms and interprismatic substance were easily distinguishable. Low-voltage operation (3 and 5 k v ) gave the best results. Specimen charging was detectable at 5 k v and caused reduced image quality at 10 and 15 k v . Application of silver paste did not reduce charging appreciably. Prolonged observation at high magnification (x 10 000) resulted in contamination of the specimen with consequent charging and reduced resolution. Dental enamel seems to be a material which is well suited when uncoated for obervation in the SEM. This may be due both to the high content of the relatively heavy atom calcium, giving good secondary electron emission, and possibly to a certain degree of conductivity caused by diffusible icons.     

Evaluation of the enamel etching capacity of six contemporary self-etching adhesives

OBJECTIVES: The purpose of this study was to evaluate the capacity of six contemporary self-etch primers/adhesives to demineralize ground enamel by means of ultrastructural analysis of the etching surface under SEM and by spectroscopic measurement of the percentage of calcium and phosphate ions dissolved. METHODS: Seventy non-carious extracted human third molars were sub-divided into 2 groups of 35 teeth each. The teeth of the first group were ground to expose flat, polished enamel surfaces 3-4mm thick. The samples thus obtained were treated with six self-etch bonding systems and a phosphoric acid gel (control group). The self-etch priming agent was then eliminated and the etched enamel surface observed by SEM. From the teeth of the second group, disc-shaped specimens were made from ground enamel and subjected to application of each of the six self-etchants. Once the etching product had been rinsed off, the rinse solution was analyzed by atomic flame spectroscopy to evaluate the percentage of calcium and phosphate ions dissolved. RESULTS: SEM images show that AdheSE, Adper Prompt L-Pop and Xeno III, despite having a less intensive etching efficacy than phosphoric acid, gave a regular pattern over a considerable surface area and depth. iBond and One-Up Bond F gave less regular demineralization. For Clearfil SE Bond, the demineralization was ineffective. Results of the percentage of mineral loss show that Adper Prompt L-Pop and Xeno III were the most efficient self-etch products. AdheSE, iBond and One-Up Bond F, respectively exhibited decreasing demineralizing capacity. Clearfil SE Bond, however, gave low proportions of calcium and phosphate ions loss and was considered unsatisfactory. CONCLUSION: The action on enamel was not the same for all self-etch systems tested. The etching potential of the self-etch adhesives was lower than that of phosphoric acid but some self-etch systems, particularly those with monomers containing phosphate derivatives, gave results close to those obtained with phosphoric acid.     

Aspects of the final phase of enamel formation as evidenced by observations of superficial enamel of human third molars using scanning electron microscopy

ObjectiveEnamel structure reflects ameloblast function. By studying the structure of the superficial enamel, information about ameloblast function toward the end of the secretory stage may be obtained.DesignThe superficial enamel in midcoronal areas of acid-etched facio-lingual sections from human third molars was studied in the scanning electron microscope (SEM).ResultsA great variation was observed in occurrence of prism-free enamel. Prism-free enamel dominated in 40% (mandibular) and 47% (maxillary) of observed areas and had a mean thickness of about 30 μm. Striations in the prism-free enamel had an interstriae distance of about 3.3–3.8 μm. The angle between prisms and enamel surface was about 60°, between prisms and Retzius lines about 45° and between Retzius lines and enamel surface about 15°. The distances between regularly occurring Retzius lines and between striations in the prism-free enamel both tended to decrease toward the enamel surface. Prisms could change direction as they approached the enamel surface, mostly in cervical direction. Where Retzius lines curved and converged occlusally, prisms tended to deviate in an occlusal direction.ConclusionsJudged from the incremental lines and occurrence of prism-free enamel, ameloblasts slow down and tend to lose their Tomes’ process as they approach the end of secretion. The crystals of prism-free enamel belong to the same system as the interprism crystals of prismatic enamel. A method, based on the disposition of fine incremental lines, is suggested for evaluation of ameloblast dynamics in the last stage of enamel secretion.     

Shear bond strength of one etch-and-rinse and five self-etching dental adhesives when used by six operators

Objective. To test the hypothesis that some single-bottle self-etching adhesives bond as well to enamel and dentin as a typical two-bottle etch-and-rinse adhesive. Material and methods. Six operators used one two-bottle etch-and-rinse dentin adhesive (Scotchbond MP) and five all-in-one self-etching adhesives (iBond Gluma Inside, Clearfil S³ Bond, iBond Experimental, Xeno IV, and G-BOND). Each operator carried out six bondings to enamel and six bondings to dentin with each adhesive. After 24 h of storage in water at 37°C, bond strength was determined in shear. Results. The pooled results of all the adhesives revealed no significant difference (p>0.05) in bond strength between dentin and enamel. However, there were significant differences (p<0.0001) between the different adhesives. The etch-and-rinse adhesive did better than the self-etching adhesives when substrate was not an issue (pooled enamel and dentin results). On comparing the performance of the different adhesives, it became clear that there were significant interactions (p<0.0001) between substrates and products. There were also significant differences (p<0.0001) between operators, and the interaction between operators and products was significant (p<0.0002). Conclusions. The tested etch-and-rinse adhesive did better than the tested self-etching adhesives. The shear bond strength results were also strongly affected by the operator as well as by the interaction between operator and used product. The pooled bond strength values of the different adhesives revealed no difference in bond strength to dentin versus enamel.     

牙釉质纳米微晶龋溶解的高分辨电镜观察

目的 在晶格水平上探讨牙釉质磷灰石纳米微晶的龋溶解机制及其与釉质微晶中心暗线的关系。方法 应用高分辨透射电镜结合氩离子减薄制样技术，对初期釉质龋病变体部的晶体结构进行观察。结果 在初期釉质龋的病变体部，釉质纳米微晶主要以中心优先溶解的方式溶解，偶见晶体周边溶解现象。单个釉质微晶的初期溶解首先表现为沿微晶中心暗线的多个亮斑，其晶格条纹模糊、弯曲或断裂，邻近亮斑可相互融合形成大的亮区，进而形成微晶的中心穿孔。龋溶解微晶的中心穿孔与中心暗线的出现部位相符，并可见中心穿孔沿中心暗线延伸。结论 牙釉质纳米微晶的初期龋溶解与品格缺陷密切相关；微晶中心优先溶解现象可部分归因于晶体的中心暗线，中心暗线可能显示微晶对龋溶解较为敏感的区域。     

Enamel tensile bond strength and morphology of resin-enamel interface created by acid etching system with or without moisture and self-etching priming system

The purpose of this study was to estimate the effect of three types of different adhesive systems on enamel adhesion. Scotchbond Multi-Purpose (MP) as a traditional system, Single Bond (SB) as a wet-bonding system and Clearfil SE Bond (SE) and Unifil Bond (UB) as self-etching priming systems were used. Bovine enamel was treated with each system and tensile bond strength (TBS) of resin to the enamel was measured. The conditioned enamel surfaces and resin-enamel interfaces were also morphologically observed with scanning electron microscope (SEM). The mean TBS for MP, SB, SE and UB were 15.3, 13.7, 14.3 and 11.6 MPa, respectively. There was no significant difference in mean TBS among all products but the traditional system showed the most stable TBS. In SEM observations, self-etching primer created a weaker etched pattern on the enamel surface than phosphoric acid. At the resin-enamel interfaces, thick tag-like extensions penetrated into the enamel etched with phosphoric acid regardless of using the wet-bonding technique, while self-etching primer created thin lamina-like resin penetrations. These results indicate that the traditional system with phosphoric acid etching exhibits the most stable enamel adhesion although the enamel-bonding promoting abilities of these adhesive systems are equivalent to each other.     

Micro-shear bond strengths and etching efficacy of a two-step self-etching adhesive system to fluorosed and non-fluorosed enamel

The purpose of this study was to evaluate the micro-shear bond strengths and the etching efficacy of a two-step self-etching adhesive system to fluorosed and non-fluorosed enamel. The extracted teeth, obtained from Australian and Japanese patients, were classified according to the severity of fluorosis, using the Thylstrup & Fejerskov index (TFI). Australian teeth were classified as mildly fluorosed (TFI = 1–3), whereas Japanese teeth were classified as non-fluorosed (TFI = 0). Resin composite was bonded to 20 enamel samples using Clearfil SE bond. The bonded samples were stressed at a crosshead speed of 1 mm min⁻¹ to determine the micro-shear bond strength. To examine the etching efficacy of primer on fluorosed and non-fluorosed enamel, the enamel-surface pH values were directly measured using a micro pH sensor. The non-fluorosed enamel showed significantly higher bond strengths compared with the fluorosed enamel. There was a statistical difference between fluorosed and non-fluorosed enamel regarding the surface pH change before and after application of the Clearfil SE bond primer. The results from this study suggest that water fluoridation has an effect on the acid resistance of enamel surfaces when treated with a two-step self-etching adhesive system and that this effect leads to reduced bond strengths.     

Platinum replicas of broken-open osteoclasts imaged by transmission electron microscopy

BackgroundPreserving the cellular structure at the highest possible resolution is a prerequisite for morphological studies to deepen our understanding of cellular functions. A revival of interest in rapid-freezing methods combined with breaking-open techniques has taken place with the development of effective and informative approaches in platinum replica electron microscopy, thus providing new approaches to address unresolved issues in cell biology.HighlightThe images produced with platinum replicas revealed 3D structures of the cell interior: (1) cell membranes associated with highly organized cytoskeletons, including podosomes or geodomes, (2) heterogeneous clathrin assemblies and membrane skeletons on the inner side of the membrane, and (3) organization of the cytoskeleton after detergent extraction.ConclusionIn this review, I will focus on the platinum replica method after brokenopen cells have been broken open with mechanical shearing or detergent extraction. Often forgotten nowadays is the use of platinum replicas with stereomicroscopic observations for transmission electron microscopy study; these “old-fashioned” imaging techniques, combined with the breaking-open technique represent a highly informative approach to deepen our understanding of the organization of the cell interior. These are still being pursued to answer outstanding biological questions.     

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目的观察不同年龄组牙釉质酸蚀后的超微结构。方法收集2012年3月至2013年3月在中国医科大学口腔医学院口腔外科拔除的牙齿24颗,分为乳牙组（9～12岁）、年轻恒牙组（10～14岁）、青年恒牙组（25～40岁）、老年恒牙组（60岁以上）。用酸蚀剂处理不同年龄组牙齿的颊侧牙釉质表面,各实验样本分别冲洗、固定、脱水、干燥、喷金,应用扫描电镜观察各组被处理表面的超微结构形态。结果乳牙组釉质表面较粗糙,釉柱排列形态不规则．相同的酸蚀时间乳牙组的牙釉质脱矿比恒牙明显。年轻恒牙组可见明显的釉柱端凹陷,釉柱表层排列松散;青年恒牙组牙釉质表面排列规整、致密,未见釉柱端凹陷;老年恒牙组牙釉质成不规则的点隙、裂沟,原有的釉质结构部分消失,蜂窝状结构明显。结论不同年龄组牙釉质抗酸能力及脱矿形式不同。     

人釉原蛋白亮氨酸富集片段的冷冻电子显微镜观察及其引导矿化性能研究

目的 采用冷冻电子显微镜观察体外重组的人釉原蛋白富亮氨酸片段（LRAP）,分析其细微结构和聚集状态,结合矿化实验评估LRAP体外引导羟磷灰石生长的定向成核能力。方法 人工合成LRAP基因,与原核表达载体pCold-SUMO行质粒构建,于宿主菌大肠杆菌BL21plys中诱导表达并纯化,在冷冻电子显微镜下观察LRAP在pH值从3.5到8.0的环境中聚合自组装的过程,并在人工唾液中通过透射电镜观察羟磷灰石晶体的生长规律。结果 通过原核表达成功得到纯度90%以上的LRAP蛋白提取物,当pH值为8.0时,LRAP能聚集成多聚体和纳米小球等功能结构,在人工唾液中能诱导羟磷灰石晶体生长成熟。结论 作为简化的釉原蛋白功能域,LRAP兼备了自组装为纳米小球和c轴诱导晶体矿化的特性,可作为运用釉基质蛋白多聚物行无细胞修复牙体硬组织缺损的备选材料之一。     

Bonding ability of 4-META self-etching primer used with 4-META/MMA-TBB resin to enamel and dentine: Primary vs permanent teeth

Objectives

The present study compared the efficacies of the self-etching Teeth Primer (TP: 4-META), and the etchants Red Activator (RA; 65% phosphoric acid) and Green Activator (GA; 10% citric acid with 3% ferric chloride), for bonding to enamel and dentine of human primary and permanent teeth, when used with 4-META/MMA-TBB resin (Bondfill SB).

Methods

Forty-eight non-carious primary canines and third molars were used. Eight groups were prepared: Group 1 (primary enamel with RA), Group 2 (permanent enamel with RA), Group 3 (primary enamel with TP), Group 4 (permanent enamel with TP), Group 5 (primary dentine with GA), Group 6 (permanent dentine with GA), Group 7 (primary dentine with TP) and Group 8 (permanent dentine with TP). Micro-tensile bond strengths (MTBS) were measured and analyzed statistically using ANOVAs and Tukey HSD tests at α = 0.05. Efficacy of etching/priming and the morphology of bonded interfaces were observed with SEM.

Results

Etching/priming efficacy of TP on enamel was low. The MTBS of Group 2 was significantly higher than the other groups (Groups 1, 3 and 4). For dentine, significant differences in MTBS were observed, in the order of Groups 6 > 8 > 7 = 5 (p < 0.05). The MTBSs of permanent dentine were significantly higher than primary dentine. For primary teeth, there was no significant difference in the MTBSs between enamel and dentine, irrespective of primer or etchant (p > 0.05).

Conclusion

TP primer/Bondfill SB may be used as an alternative to other adhesive/resin composite systems for bonding to enamel and dentine of primary teeth.