Acidity of conventional luting cements and their diffusion through bovine dentine

AIM: To examine the changes in pH of luting cements and acid diffusion of luting cements through bovine dentine using a pH-imaging microscope (SCHEM-100; Horiba Ltd, Kyoto, Japan). METHODOLOGY: The pH of the surface of three conventional luting cements, glass-ionomer, zinc phosphate and zinc polycarboxylate was measured with SCHEM-100 for 1 month. The acid diffusion from the three luting cements through bovine dentine was investigated by measuring pH changes during the application of each luting cement on the bovine dentine surface. Coronal bovine dentine disks were prepared to thicknesses of 0.50 and 0.25 mm. Each luting cement was placed on the labial dentine surface, and the pH change of the pulpal surface was observed every 3 min for 30 min with SCHEM-100. RESULTS: Glass-ionomer showed the lowest pH values for longer times. Neutralization proceeded furthest in zinc polycarboxylate. The 0.5-mm-thick dentine disks showed no pH change on the pulpal side with all the three cements. The 0.25-mm-thick disks revealed evidence of acid diffusion on the pulpal side of the cemented dentine and significantly lower pH when cemented with glass-ionomer and zinc phosphate than with zinc polycarboxylates. CONCLUSIONS: This study demonstrated that glass-ionomer exhibited a lower setting pH than zinc phosphate and zinc polycarboxylate, and acid diffusions from glass-ionomer and zinc phosphate cements were observed when placed on 0.25-mm-thick dentine disks.     

����ճ��ϵͳ��Ӳ���������ʴ����ij�΢��̬�۲�

目的观察硬化性牙本质经全酸蚀粘接处理和自酸蚀粘接处理后混合层的超微结构。方法2006年12月至2007年5月,在大连医科大学附属一院口腔科选择具有典型硬化性牙本质的磨牙10颗作为实验组,另选择因正畸拔除的正常前磨牙作为对照组,每颗牙分成两部分。一部分应用全酸蚀粘接处理牙本质,另一部分应用自酸蚀粘接处理牙本质,每一部分都经液氮冷冻后劈裂,利用扫描电镜观察粘接混合层。结果硬化性牙本质经全酸蚀处理或自酸蚀处理获得的混合层与牙本质结合紧密,混合层厚度有些区域较宽,有些区域较薄。结论从微观形态角度观察混合层:全酸蚀系统及自酸蚀系统对正常牙本质获得的混合层与硬化性牙本质获得的混合层无明显差别。     

两种粘结系统处理硬化性牙本质后树脂突形成的扫描电镜观察

目的：观察硬化性牙本质经全酸蚀粘结处理和自酸蚀粘结处理后混合层树脂突情况。方法：选择具有典型硬化性牙本质的10颗磨牙作为实验组,另选择因正畸拔除的正常前磨牙作为对照组。每颗牙分成两部分,一部分应用全酸蚀粘结剂处理牙本质,另一部分应用自酸蚀剂处理牙本质,每一部分金刚砂车针分割成两个剖面,每一剖面酸蚀、固定、脱水、扫描电镜观察。结果：正常牙本质较硬化性牙本质经全酸蚀处理视野中更多见树脂突伸向牙本质小管。两种牙本质经自酸蚀处理视野中树脂突都不明显,有些区域似有树脂突但短小。结论：硬化性牙本质较正常牙本质粘结处理后混合层树脂突少;全酸蚀粘结剂较自酸蚀粘结剂对牙本质处理混合层更易形成树脂突。     

The effect of thermal cycling on the bovine dentine shear bond strength of current adhesive systems

The aim of this study was to evaluate the effect of thermal cycling on shear bond strength to bovine dentine of four current adhesive systems. Forty bovine incisors were ground flat with #600-grit silicon carbide paper to obtain superficial coronal dentine surfaces. Three one-bottle (etch and rinse) adhesive systems (Single Bond, Bond 1, One Step), and one self-etching primer adhesive system (Clearfil Liner Bond 2V) were evaluated. Dentine was conditioned and bonded with the adhesive systems tested according to the manufacturers' instructions. A cylindrical teflon mould (3 x 4 mm) was placed over the bonded area (to eliminate the bonded surface) and filled with composite resin. For each adhesive system the filling composite used was from the same manufacturer. Ten specimens were prepared for each material and all specimens were conditioned at 37 degrees C for 24 h. Five specimens of each material (half of the specimens) were thermocycled at 5000 cycles (at 5, 37, 55 and 37 degrees C) with a dwell time of 15 s and bonds were stressed in shear at a rate of 0.5 mm min(-1) until failure. Data were analysed by one-way anova and Student-Newman-Keuls rank test (alpha=0.05). Statistical analysis revealed that thermal cycling significantly (P < 0.05) reduced the bond strengths of all adhesive systems. Bond strengths prior to thermocycling were not significantly different (P > 0.05), except for One Step which revealed the lowest bond strength, and varied from 22.5 +/- 3.34 to 10.98 +/-0.87 MPa. After thermal cycling, the bond strengths ranged from 9.35 +/- 1.13 to 6.06 +/- 1.77 MPa. Failures after testing and prior to thermal cycle were most commonly adhesive failures between the bonding resin and dentine associated with partial cohesive failures in the adhesive resin (type 2). Adhesive failures between bonding resin and dentin (type 1) after thermocycling were most commonly seen.     

����ͿĨ������ƻ���Ԥ��������֢״��Ч�۲�

目的    观察全冠修复时黏结剂涂布预备后的基牙对敏感症状的改善情况。方法    选择2007年1月至2009年12月盘锦市第一人民医院口腔科及吉林大学口腔医院种植中心拟进行烤瓷修复的患者87例（患牙224颗）,根据随机数字表将患牙随机分为试验组（112颗）和对照组（112颗）。牙体预备后,试验组涂布Prime＆Bond NT黏结剂,对照组不做任何处置。临时冠摘除后进行相关指标检测,比较观察试验组和对照组的临床疗效。结果    在探诊、冷风刺激和冷水冷诊的检测中,试验组的疼痛视觉模拟评分法（VAS）测量值与对照组比较,差异均有统计学意义（P < 0.05）。结论    应用Prime＆Bond NT黏结剂能有效改善牙体预备后牙本质敏感症状。     

In vivo evaluation of microleakage from composites with new dentine adhesives

The purpose of this study was to investigate microleakage in V class composite restorations with total etch versus self-etching adhesives. Experiments were conducted in vivo and were also evaluated interfacial micromorphology. Forty class V cavities were prepared on the buccal surfaces of teeth in three healthy dogs. The cavities were randomly assigned into five groups of eight teeth and restored with one of the following adhesive systems: Etch and Prime 3.0/Definite flow/Definite, Prompt L-pop/Filtek flow/P-60, Admira bond/Admira Flow /Admira, Bond 1/Flow it/Alert, Stae/Wave/Glacier. After 60 days the animals were killed and the teeth were extracted. The teeth were then immersed in a solution of 0.5% basic fuchsin dye for 24 h, sectioned and scored for microleakage. Features of the tooth/restoration interfaces were also examined using Scanning electron microscopy. Student-Newman-Keuls and one-way anova revealed significance differences among the groups for overall wall scores (P < 0.05). The total-etch adhesives revealed significantly less microleakage scores than the self-etching adhesive systems tested. Wilcoxon Signed Ranks Test revealed significant differences between the occlusal and gingival microleakage scores for each adhesive restorative system, with the exception of Admira (P < 0.05).     

In vitro diffusion of hydroxyl ions through root dentine from various calcium hydroxide medicaments

The purpose of this study was to determine diffusion of hydroxyl ions through dentine from different calcium hydroxide [Ca(OH)2] medicaments. Forty-five single-rooted teeth were instrumented and cavities (3 mm in diameter and 1 mm in depth) were prepared on the facial surface of each root. After smear layer was removed with 17% EDTA all surfaces of roots, except cavities, were coated with nail polish. Teeth were randomly divided into four experimental groups (each 10 samples) and a control group (five samples). They were filled with: group 1, Ca(OH)2 and distilled water mixture; group 2, TempCanal; group 3, Calasept; and group 4, Ca(OH)2 plus point. Control group, in which nothing was applied to the canals. All samples were immersed in distilled water maintained at 37 degrees C. pH values were measured at 1 h, 2 h, 3 h, 24 h, 48 h, 72 h, 4 days, 5 days, 6 days, 7 days and 14 days. Ca(OH)2-distilled water mixture and TempCanal showed highest pH values at 24 h. Calasept, Ca(OH)2 plus point and control showed highest pH values at 3 h. Time intervals after 24 h, Ca(OH)2-distilled water mixture, TempCanal and Calasept showed higher pH values than Ca(OH)2 plus point, with a statistically significant difference (P<0.05). The pH value of Ca(OH)2 plus point was lower than the values of other materials after 3 h. This study indicates that non-setting Ca(OH)2 based materials have an effective release of hydroxyl ions compared with Ca(OH)2 plus point.     

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.     

A combined radiographic and computerized scanning method to evaluate remaining dentine thickness in mandibular incisors after various intracanal procedures

AIM: To develop a computerized model to evaluate remaining dentine thickness after various intracanal procedures. METHODOLOGY: A three-step model was developed, in which injection of radiopaque solution into the root-canal space of 20 extracted mandibular incisors, exposure of periapical radiographs from two directions, and computerized scanning and printing of the image were combined. Following root-canal preparation and preparation of post space, evaluation of remaining dentine thickness was completed using appropriate software. RESULTS: Remaining dentine thickness was significantly affected (P < 0.01) by place (mesial-distal more than buccal-lingual), stage (root-canal preparation more than post space) and location (coronal more than middle and apical). CONCLUSIONS: This in vitro study confirmed that in an oval root-canal space, the mesial and distal aspects are mainly affected by intraradicular procedures. The three-step method is a useful tool to evaluate root-canal instrumentation as the root or tooth can remain intact during the procedure.     

Effect of ethanol-wet bonding with hydrophobic adhesive on caries-affected dentine

Frequently encountered in clinical practice, caries-affected dentine (CAD) is the most challenging bonding substrate. This study evaluated the effect of ethanol-wet bonding with hydrophobic adhesive to sound dentine and to CAD. In the control groups, prepared sound dentine and CAD were bonded with Adper Single Bond 2 using a traditional water-wet bonding technique. In the experimental groups, the specimens were treated as follows: Group 1, rinsed with stepwise ethanol dehydration; Group 2, immersion in 100% ethanol, three times, for 20 s each time; and Group 3, immersion in 100% ethanol for 20 s. Microtensile bond strength (μTBS) testing was used to evaluate the effects of the different protocols on bonding. The microhardness of debonded dentine surfaces was measured to ensure the presence of CAD. Interfacial nanoleakage was evaluated by field-emission scanning electron microscopy. Treatment significantly improved the μTBS in CAD in Groups 1 and 2, but had no effect on Group 3. Conversely, treatment significantly reduced the μTBS in sound dentine in Groups 2 and 3, but had no effect in Group 1. The presence of nanoleakage varied with the ethanol-wet protocol used. In conclusion, ethanol-wet bonding can potentially improve bond efficacy to CAD when an appropriate protocol is used.     

Micro-tensile bond strength of self-etching primer adhesive systems to human coronal carious dentin

The aim of this study was to evaluate the micro-tensile bond strengths of three self-etching primer adhesive systems to normal dentin (ND), caries-affected dentin (CAD) and caries-infected dentin (CID). Human extracted molars with caries were used, and flat dentin surfaces ground by 600-grit SiC paper were prepared. The surfaces were dyed using Caries-Detector solution, treated with Clearfil SE Bond, Mac-Bond II and UniFil Bond, and then covered with resin composites according to manufacturer's instructions. After immersion in 37 degrees C water for 24 h, the teeth were serially sectioned into multiple slices. Each slice was distinguished into ND, CAD and CID groups by the degree of staining, and the bond strength was measured in a universal testing machine. Scanning electron microscopic (SEM) observation was also performed. For statistical analysis, anova and Scheffe's test were used (P < 0.05). The bond strengths of the three adhesive systems to CAD and CID were significantly lower than those to ND. There was significant difference in the bond strength to ND between Clearfil SE Bond and UniFil Bond, but no significant differences to CAD and CID among the three adhesive systems. On SEM, the hybrid layers in CAD and CID showed more porous structures compared with ND. The results indicated that the bond strengths to CAD and CID were not affected by a variety of self-etching primer adhesive systems because of the porous hybrid layer formation in carious dentin.     

Quantitative micro-Raman assessment of dentine demineralization, adhesive penetration, and degree of conversion of three dentine bonding systems

Unreacted monomers in adhesive systems may cause a reduction in material properties, an increase in the long-term instability of the restoration, and pulpal irritation. The degree of dentine demineralization, adhesive penetration, and the degree of conversion (DC) across the dentine–adhesive interface of self-etch adhesives were measured using micro-Raman spectroscopy. Two-step, self-etch AdheSE, one-step self-etch AdheSE One, and etch-and-rinse Excite (control) (Ivoclar Vivadent AG, Schaan, Liechtenstein) were studied. Nine human molars were allocated to three groups and a flat dentine surface was prepared. A smear layer was produced by grinding dentine with 600-grit silicone-carbide discs under water. After application and polymerization of the adhesive, teeth were sectioned to produce four 1–mm-thick slices per tooth for micro-Raman spectroscopy. There were statistically significant differences in the depth of dentine demineralization between all adhesives. The depth and degree of demineralization decreased in the order: Excite>AdheSE>AdheSE One. The mean ± standard deviation (SD) values for DC within the adhesive layer were 85.2 ± 2.9% (Excite), 81.4 ± 4.2% (AdheSE), and 54.3 ± 10.1% (AdheSE One), and within the hybrid layer were 55.2 ± 22.5% (Excite), 65.1 ± 16.9% (AdheSE), and 42.0 ± 16.2% (AdheSE One). All systems showed a discrepancy between dentine demineralization and adhesive penetration. A significant amount of unreacted monomers were associated with all systems but particularly with the etch-and-rinse system.     

G-BOND����ʴ��ϵͳ����Ш״ȱ���޸�53���ٴ�Ч���۲�

目的    研究G-BOND自酸蚀黏结系统用于牙颈部楔状缺损修复的临床疗效。方法    选择2009年3月至2010年3月在大连大学附属中山医院口腔科就诊的口内有多颗颊侧颈部楔状缺损牙的患者53例（共187颗患牙）,采用自身配对方法将患牙随机分为2组。试验组（94颗患牙）使用G-BOND自酸蚀黏结系统;对照组（93颗患牙）使用Adper Scotchbond全酸蚀黏结系统。治疗后7 d、6个月、12个月复查,以改良的美国公共健康部（USPHS）制定的评定系统标准记录修复效果,对各组患牙的治疗效果进行比较分析。结果    治疗后6个月失访2例,12个月失访3例。治疗后7 d、6个月、12个月两组修复体固位率均为100％,无脱落,无继发龋。在12个月时,试验组和对照组各有2、3颗患牙边缘完整性不佳和边缘着色,组间差异无统计学意义（P > 0.05）。在术后敏感方面,治疗后7 d复查试验组无敏感症状出现,对照组有4颗患牙出现了敏感症状,两组间差异具有统计学意义（P < 0.05）。结论    G-BOND自酸蚀黏结系统应用于修复楔状缺损的治疗效果可靠。     

复合树脂联合两种酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度比较

目的:比较复合树脂联合全酸蚀和自酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度。方法:收集新鲜拔除的滞留乳磨牙48个,随机分为4组,分别制备全酸蚀和自酸蚀粘结剂的釉质和牙本质试件,电子万能试验机测定各组剪切强度;体视显微镜下观察试件断面的破坏模式;扫描电镜观察粘结界面情况。结果:全酸蚀粘结剂组的釉质剪切强度明显高于牙本质剪切强度(P<0.05);自酸蚀粘结剂组釉质与牙本质剪切粘结强度无统计学差异(P>0.05);全酸蚀粘结剂组的釉质、牙本质剪切粘结强度均明显高于自酸蚀粘结剂组(P<0.05);体视显微镜及扫描电镜观察均显示,全酸蚀粘结剂与釉质和牙本质的粘结界面结合程度好于自酸蚀粘结剂。结论:全酸蚀粘结剂处理对乳牙釉质及牙本质的剪切粘结强度高于自酸蚀粘结剂。     

龋病影响牙本质自酸蚀粘接修复的研究进展

自酸蚀粘接系统适用于牙本质和釉质的粘接,具有操作简单、修复体边缘封闭性良好、术后敏感低等优点,有很好的发展前景.在临床工作中,龋坏引起的牙体缺损是临床修复的主要内容.临床上,医生在去除龋坏时,建议只去除细菌入侵的那部分牙本质,而已脱矿却无细菌入侵的牙本质,即龋坏影响牙本质(CAD),是临床粘接的主要部分.与正常的牙本质...     

Association of bovine dentine phosphophoryn with collagen fragments

Bovine dentine phosphophoryn (BDP), a protein rich in aspartyl (Asp) and O-phosphoseryl (Ser(P)) residues, is synthesized by odontoblasts and believed to be involved in matrix-mediated biomineralization of dentine. Phosphophoryn was purified from bovine dentine using EDTA extraction, Ca(2+) precipitation, anion exchange and size exclusion chromatography. The purified protein migrated on SDS-PAGGE as a single band. The protein was dephosphorylated using a chelex alkaline dialysis procedure, repurified using anion exchange and size exclusion chromatography and then subjected to cleavage with trypsin. The digest was subjected to reversed-phase HPLC and analysed by Q-TOF mass spectrometry. The only non-trypsin peptides that could be identified were two collagen Type I alpha2 peptides whose sequence was determined by fragmentation analysis. The association of collagen fragments with highly purified phosphophoryn suggests that the EDTA extraction method yields BDP that is strongly bound to collagen fragments. This association now helps explain discrepancies in molecular weight and amino acid composition data for various phosphophoryn preparations compared with the same data calculated from the C-terminal extension of mouse, rat and human dentine sialophosphoprotein (DSPP) gene products. Analysis of the mutation pattern of the clinical disorder Osteogenesis Imperfecta within the region enclosed by the identified collagen fragments reveals that phosphophoryn associates with a segment of collagen that is crucial for structure and/or function.     

Er:YAG激光联合3M ESPE Adper Easy-one粘结剂堵塞牙本质小管的体外研究

目的:研究Er:YAG激光联合3M ESPE Adper Easy-one自酸蚀树脂粘结剂堵塞牙本质小管的效果,为其治疗牙本质敏感提供实验室依据。方法:选择因正畸需要拔除的牙体完整、无龋损的前磨牙8个,制备牙颈部牙本质小管暴露的牙本质样本32个,按处理方法不同随机分为4组:空白对照组、Er:YAG激光处理组、3M ESPE Adper Easy-one粘结剂处理组、Er:YAG激光、3M ESPE Adper Easy-one粘结剂联合处理组,扫描电镜下比较牙本质表面超微形态、纵断面的粘结剂牙本质界面的混合层、树脂突的微观表现,观察牙本质小管的堵塞效果。结果:Er:YAG激光联合3M ESPE Adper Easy-one粘结剂组与粘结剂组的堵塞牙本质小管的表面微观形态类似,牙本质小管被完全堵塞;激光处理组的牙本质小管基本完全堵塞;纵断面观察联合组粘结界面可见到清晰的混合层和树脂突,且树脂突深度较粘结剂组明显增加,激光组纵断面牙本质小管内无明显堵塞物。结论:Er:YAG激光与3M ESPE Adper Easy-one粘结剂联合处理能够有效的堵塞牙本质小管。     

ElectroBond application may improve wetting characteristics of etched dentine

Objective

To assess the efficacy of an electrically assisted application technique on dentine wettability (water contact angle measurements) and to determine the promoted surface roughness of dentine after applying 37% phosphoric acid etching, a self-etching primer or a self-etching adhesive system.

Methods

Wettability was assessed on 30 caries-free extracted human third molars. Specimens were sectioned parallel to the occlusal surface to expose moderately deep dentine and ground flat (water-wet 180-grit SiC) to provide uniform flat surfaces. 37% H₃PO₄, Clearfil SE Bond (CSEB) primer or Prompt-L-Pop (PLP) adhesive system were applied on dentine surfaces. In half of the specimens, the electric impulse-assisted application technique/ElectroBond-assisted application was followed. Contact angle measurements were performed to assess wettability using the Axisymmetric Drop Shape Analysis technique. Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Two-way ANOVA, Student's t and Student-Newman-Keuls tests were performed (P < 0.05).

Results

PLP-treated dentine showed the highest intertubular roughness and the lowest dentine wettability. ElectroBond application reduced water contact angles when dentine was treated with H₃PO₄ or Clearfil SE Bond primer, but not when dentine was treated with PLP.

Conclusions

The use of electric current improved wettability of dentine surface following application of phosphoric acid and a mild self-etch primer, but not self-etch adhesive.     

Inactivation of root canal medicaments by dentine,hydroxylapatite and bovine serum albumin

AIM: This study examined and compared the inhibition of the antibacterial effect of saturated calcium hydroxide solution, chlorhexidine acetate and iodine potassium iodide by dentine, hydroxylapatite and bovine serum albumin. METHODOLOGY: Enterococcus faecalis strain A197A prepared to a suspension of 3 x 10(8) cells per ml in 0.5% peptone water was used. Fifty microL of saturated calcium hydroxide solution, 0.05% chlorhexidine acetate or 0.2/0.4% iodine potassium iodide were incubated at 37 degrees C with 28 mg dentine powder (DP), hydroxylapatite (HA) or bovine serum albumin (BSA) in 50 microL water for 1 h before adding 50 microL of the bacterial suspension. Samples for bacterial culturing were taken from the suspension 1 and 24 h after adding the bacteria. In further experiments, the amount of dentine was stepwise reduced from 28 mg 150 microL-1 to 2.8 mg 150 microL-1. RESULTS: Calcium hydroxide was totally inactivated by the presence of 28 mg of DP, HA or BSA. Chlorhexidine (0.05%) was strongly inhibited by BSA and slowed down by dentine. However, HA had little or no inhibitory effect on chlorhexidine. The antibacterial effect of 0.2/0.4% iodine potassium iodide on E. faecalis was totally inhibited by dentine (28 mg), but was practically unaffected by HA or BSA. A stepwise reduction of dentine from 28 mg 150 microL-1 to 2.8 mg 150 microL-1 was followed by a similar reduction of the inhibition of the antibacterial activity of chlorhexidine. Iodine potassium iodide was not inhibited at all with dentine amounts less than 28 mg. However, the effect of saturated calcium hydroxide solution was totally eliminated by dentine, in all four concentrations. CONCLUSION: Inhibition by dentine of the antibacterial activity of calcium hydroxide, chlorhexidine and iodine potassium iodide occurs by different mechanisms. Different components of dentine may be responsible for the inhibition of these three medicaments. Calcium hydroxide was particularly sensitive to inhibition by both inorganic and organic compounds.