玻璃离子与光固化树脂封闭剂封闭乳牙窝沟

背景：传统方法玻璃离子作为封闭剂耐磨性能差,抗折强度低,位于合面的封闭剂很容易脱落,很难取代树脂封闭剂。 目的：观察光固化树脂封闭剂和非创伤性充填技术玻璃离子窝沟封闭幼儿乳牙的效果。 方法：按同人半口随机比较的方法,对89名3岁幼儿的左或右半口符合窝沟封闭条件的乳磨牙在非创伤性充填技术下行玻璃离子窝沟封闭,对侧半口符合窝沟封闭条件的乳磨牙进行树脂封闭。 结果与结论：窝沟封闭后6,18个月玻璃离子组封闭物脱落率均低于树脂材料组(P < 0.05)。玻璃离子材料最易脱落的牙位是下颌第二乳磨牙;树脂材料最易脱落的牙位是上颌第二乳磨牙。封闭后6个月,玻璃离子组封闭的乳牙患龋率低于树脂材料组,18个月时两组间差异无显著性意义。说明非创伤性充填技术玻璃离子窝沟封闭幼儿乳牙的脱落率低,操作简单,防龋效果肯定,且成本低,在经济学上可行性优于树脂封闭。     

Salivary Bisphenol-A Levels due to Dental Sealant/Resin: A Case-Control Study in Korean Children

Dental sealants and composite filling materials containing bisphenol-A (BPA) derivatives are increasingly used in children. The aim of this study was to evaluate the association between salivary BPA and the number of tooth surfaces filled with dental sealant, and to determine a cutoff BPA level. Salivary BPA concentration and the number of tooth surfaces filled with dental sealant/resin were determined in 124 age and gender matched children: 62 controls had no dental sealant/resin on their tooth surfaces and 62 cases had more than 4 tooth surfaces with dental sealant/resin. Analysis of covariance (ANCOVA) and conditional logistic regression were performed after controlling for age, gender, salivary flow rate, salivary buffer capacity, frequency of snacking, and frequency of tooth brushing. Salivary BPA levels were 0.002 to 8.305 μg/L. The BPA level of control (0.40 μg/L) was significantly lower than that of case (0.92 μg/L) after controlling for confounders (P = 0.026). Although the 90th BPA percentile had an adjusted OR of 4.58 (95% CI 1.04-20.26, P = 0.045), the significance disappeared in the conditional logistic model. There may be a relationship between salivary BPA level and dental sealant/resin.     

高强度玻璃离子材料结合非创伤性充填技术应用于乳牙封闭防龋

背景：以往报道的玻璃离子封闭剂耐磨性能差,抗折强度低,合面封闭剂很容易脱落。 目的：观察在非创伤性充填技术下高强度玻璃离子应用于幼儿乳牙窝沟封闭的效果。 方法：按自身对照的方法,对89名3岁幼儿的左或右半口符合窝沟封闭条件的乳磨牙在非创伤性充填技术下行玻璃离子窝沟封闭,对侧半口符合窝沟封闭条件的乳磨牙作空白对照。 结果与结论：非创伤性充填技术下窝沟封闭后6,18个月,玻璃离子完整保留率为94.15%及77.72%。6个月时牙位脱落率：下颌第二乳磨牙>下颌第一乳磨牙>上颌第二乳磨牙>上颌第一乳磨牙,18个月时牙位脱落率：下颌第二乳磨牙>上颌第二乳磨牙>下颌第一乳磨牙>上颌第一乳磨牙。非创伤性充填技术下玻璃离子封闭的乳牙患龋率远低于未作封闭的乳牙,6,18个月时差异均有显著性意义(P < 0.01)。提示非创伤性充填技术下高强度玻璃离子窝沟封闭在幼儿乳牙中的脱落率低,操作简单,防龋效果肯定。     

流动纳米树脂预防性窝沟龋充填

背景：预防性树脂充填术由于不采用传统的预防性扩展,只去除少量的龋坏组织后即用复合树脂或玻璃离子材料充填龋洞,而未患龋的窝沟使用封闭剂保护。 目的：通过应用美国3M公司生产的Filtek Z350流动纳米树脂对窝沟可疑龋、初龋磨除后进行预防性充填,观察并评价其临床效果,探索预防性充填治疗早期窝沟龋的新方法。 方法：对196例6~25岁患者磨牙的牙合 面窝沟龋在去除龋坏的牙体组织后,采用Eadper prompt自酸蚀粘结技术,用Filtek Z350流动纳米树脂对整个牙面进行预防性充填术,并采用对侧同名牙或邻牙也有窝沟龋者用同一公司生产的ClinproTM可见光固化变色窝沟封闭剂充填作对照研究。 结果与结论：随治4年后发现该方法涂膜保留率高,能有效阻止龋病的进一步发展。实验组与对照组在术后1,2年时的涂膜保留率差异无显著性意义,而在第3,4年时差异有显著性意义(P < 0.01、P < 0.05)。龋病发生率在1,2年时差异无显著性意义,而在3,4年时差异有显著性意义(P < 0.05)。提示Filtek Z350流动纳米树脂预防性窝沟充填是一种有效阻止窝沟早期龋进一步发展的方法。     

Selective removal of composite sealants with near-ultraviolet laser pulses of nanosecond duration

It is often necessary to replace pit and fissure sealants and composite restorations. This task is complicated by the necessity for complete removal of the remaining composite to enable suitable adhesion of new composite. Previous studies have shown that 355-nm laser pulses from a frequency-tripled Nd:YAG laser can selectively remove residual composite after orthodontic bracket removal on enamel surfaces. Our objective is to determine if such laser pulses are suitable for selective removal of composite pit and fissure sealants and restorations. Optical coherence tomography is used to acquire optical cross sections of the occlusal topography nondestructively before sealant application, after sealant application, and after sealant removal. Thermocouples are used to monitor the temperature in the pulp chamber during composite removal under clinically relevant ablation rates, i.e., 30 Hz and 30 mJ/pulse. At an irradiation intensity of 1.3 J/cm2, pit and fissure sealants are completely removed without visible damage to the underlying enamel. At intensities above 1.5 J/cm2, incident laser pulses remove the resin layer while at the same time preferentially etching the surface of the enamel. Temperature excursions in the pulp chamber of extracted teeth are limited to less than 5 degrees C if air-cooling is used during the rapid removal (1 to 2 min) of sealants, water-cooling is not necessary. Selective removal of composite restorative materials is possible without damage to the underlying sound tooth structure.     

FiltekTM Z 350纳米流动树脂微创修复细小窝沟龋

背景：传统的细小窝沟龋修复需要按Ⅰ类洞形进行预备,对牙体组织破坏较多。 目的：评价流动纳米树脂微创修复细小窝沟龋的临床效果。 方法：选择14~30岁磨牙有窝沟龋且对侧同名牙或邻牙也有窝沟龋患者167例,在一侧磨牙牙合面窝沟龋去除龋坏牙体组织后,采用Adper Single Bond 2全酸蚀黏结技术,用Filtek ^TM Z350流动纳米树脂充填整个微创窝洞作为实验组,对侧同名牙或邻牙窝沟龋用同一公司生产的Filtek ^TM Z350纳米树脂充填作对照。 结果与结论：随访2年后发现实验组Z350流动纳米树脂填充体保留率高,边缘完整性好,边缘着色率低,树脂保留率、边缘完整性及边缘着色率高于对照组(P < 0.05)。提示Filtek ^TM Z350流动纳米树脂微创窝沟充填可有效修复细小窝沟龋。     

Effect of load cycling and in vitro degradation on resin-dentin bonds using a self-etching primer

The objective of this study was to evaluate the effect of in vitro degradation and mechanical loading on microtensile bond strength (MTBS) and microleakage (ML) of a resin composite to dentin using a self-etching primer adhesive [Clearfil SE Bond (SEB)] under two hydration statuses. Twenty-four flat dentin surfaces were divided in groups: 1) blot-dried, 2) air-dried. SEB was applied and resin buildups were performed with Tetric Ceram. Specimens were divided in four subgroups: a) sectioned into beams, b) load cycled, c) beams were immersed in NaOCl for 5 h, d) load cycled and immersed in NaOCl. Beams were tested in tension. For ML testing, 80 Class V cavities were prepared and molars divided in subgroups as described above (in group c and d, specimens were kept in distilled water for 1 year, instead of the 5-h NaOCl immersion). ML was assessed by dye penetration. Analysis of variance and multiple comparisons tests were used for MTBS. For ML, Mann-Whitney U and Wilcoxon matched pairs signed ranked were used (p<0.05). SEB applied to completely dehydrated dentin produced the highest MTBS, at 24-h evaluation. In vitro degradation always decreased MTBS, and fatigue loading only diminished MTBS on dehydrated dentin. Load cycling increased dye penetration on dentin margins. Degradation always increased ML in both enamel and dentin margins.     

Microleakage and interfacial morphology of self-etching adhesives in class V resin composite restorations

The purpose of the study was to evaluate the marginal leakage of three adhesive systems in Class V resin composite restorations. Two adhesive systems containing acidic primers: Clearfil SE Bond (CSEB) and Etch & Prime 3.0 (E&P), were compared with a conventional water-based primer: Scotchbond Multipurpose Plus (SBMP). Class V cavities were made at the cementum-enamel junction of extracted human molars, which were then divided between three groups. One of the adhesive systems was applied to each group following manufacturers' instructions. Composite restorations were placed, light cured for 40 s, and polished. Specimens were then immersed in a solution of 2% basic fuchsin dye for 24 h. Longitudinal sections were obtained and studied with a stereomicroscope for assessment of the microleakage according to the degree of dye penetration (scale of 0-3). Data were analyzed by Kruskal-Wallis one-way ANOVA, Mann-Whitney tests, and the Wilcoxon matched-pairs signed rank test. Two specimens for each group were analyzed by scanning-electron microscopy (SEM). Bonded interfaces of dentin were also examined by transmission-electron microscopy (TEM). On enamel, there were no significant differences between the three groups. On dentin, CSEB showed the lowest dye penetration values among the three adhesive systems. SEM and TEM studies showed hybrid layer and resin tag formations in all groups.     

Development of adhesive pit and fissure sealants using a MMA resin initiated by a tri-n-butyl borane derivative

A new adhesive fissure sealant, which consists of a solution of 3% 2-hydroxy-3-beta-naphthoxypropyl methacrylate in methyl methacrylate (MMA), poly-MMA powder and an oxidized tri-n-butyl borane, a polymerization initiator, was developed. Tensile bond strength between an acid-etched bovine enamel and a poly-MMA bar joined by this sealant was 60 kg/cm2, and the value did not decrease much after 30 days immersion in water at 37 degrees C. Penetration of fuchsin into the sealant-enamel interface during a percolation test was not observed. SEM observation showed no voids between the enamel and the cured sealant.     

Studies on dental fluoride-releasing polymers IV: Fluoridation of human enamel by fluoride-containing sealant

An experimental fluoride-containing acrylic sealant was prepared using methacryloyl fluoride-methyl methacrylate copolymer as powder component. The in vitro fluoride acquisition by human enamel coated with the sealant after 11, 21, 41 and 84 days of incubation in a phosphate buffer of pH7 at 37°C was determined. Fluoride penetration and uptake were increased by prolonging the exposure time of enamel to the sealant. Most of the fluoride retained in enamel was found to be present as fluorapatite. The discharge of fluoride in the sealant was about 12% of initial load after 84 days of immersion.     

Blood-brain barrier permeability and immobilization stress

The regional capacity of the blood-brain barrier (BBB) has been investigated in rat brain during normal conditions and after acute immobilization (IMO). The BBB function was monitored by fluorescence microscopical localization of systemically administered vital dye (trypan blue) and by studying the ability of the brain capillaries to decarboxylate and trap injected L-DOPA. The results demonstrated clear signs of dye penetration into the parenchyma of certain brain regions (area preoptica, some hypothalamic nuclei, area ventralis tegmenti and ventral part of the pons and medulla oblongata) in addition to the areas known to be ‘outside the BBB’ (the circumventricular organ). There was an apparent increase in dye penetration in these regions after IMO, most pronounced in the reticular formation of the brain stem. In the mesencephalic reticular formation ruptures of a substantial number of vessels occurred after IMO leading to massive leakage of dye into surrounding brain parenchyma. The main finding after L-DOPA administration was indications of a more efficient decarboxylation and trapping of L-DOPA in most brain regions after IMO. The findings of dye penetration in certain brain regions, which are known to be involved in autonomic regulation, may reflect possible ways of chemical communication between the circulation and neuronal structures in these regions and/or possibly constitute the basis for inactivation processes for transport of substances outwards from the brain as well as potential loci for adverse effects and development of pathological conditions.     

无创渗透树脂材料修复早期乳牙邻面龋

背景：乳牙早期邻面龋因解剖位置的原因菌斑不易去除,常规再矿化治疗疗效不佳。 目的：观察无创渗透树脂技术治疗乳牙早期邻面龋的临床疗效。 方法：选择乳牙邻面早期龋的患牙120颗,随机分为渗透树脂组和流动树脂组,每组60颗,分别应用渗透树脂和流动树脂进行治疗,治疗后1年随访,对患者邻面龋的牙体形态、去除釉质脱矿造成的白垩色斑和色泽稳定性、继发龋和治疗成功率方面进行临床评价。 结果与结论：两组患者在充填治疗后1年的疗效检查结果中发现,渗透树脂组邻面龋的牙体形态、去除釉质脱矿造成的白垩色斑以及色泽稳定性、继发龋方面均好于流动树脂组。渗透树脂组的治疗成功率96.7%远高于流动树脂组的76.7%,差异有显著性意义(P < 0.05)。无创渗透树脂材料是目前阻断龋病发展简便高效的方法。     

Variability of cytotoxicity and leaching of substances from four light-curing pit and fissure sealants.

It was the aim of our study to investigate the composition and cytotoxicity of aqueous extracts of four light-curing pit and fissure sealants. Water extracts were analyzed by gas chromatography/mass spectrometry (GC/MS), and relative quantities of identified compounds were compared by means of an internal caffeine standard [%CF]. Cytotoxic effects due to medium extracts were determined by means of permanent 3T3 fibroblasts. All light-curing pit and fissure sealants segregated different ingredients into water, such as co-monomers (mainly ethylene glycol compounds) and initiating substances (e.g., camphorquinone). Bisphenol-A, however, which is easily detected by GC/MS, was not found in any of the analyzed eluates. The extracts of three sealants inhibited monolayer growth only moderately whereas the eluate of one product inhibited cell proliferation significantly. In the extracts of this sealant high quantities [%CF] of the co-monomer TEGDMA were detected. Our results indicate that light-curing pit and fissure sealants release substances into aqueous media that may induce cytotoxic effects. However, no concerns about potential estrogenic effects of Bisphenol-A are supported by our results.     

Resin penetration through submicrometer hiatus structures: a SEM and CLSM study

The purpose of this study was to confirm the existence of submicrometer hiatus structures and to examine the degree of resin penetration through these formations. Dentin disks 2.0 mm in thickness were sectioned from 48 human molars with the use of a microtome saw. Three different fifth-generation (total-etch, combined primer/resin) dentin adhesive systems were used to bond a light-cured, resin-based composite to the dentin disks (n = 16 each group). Bonded disks from the three groups were then sectioned. Half of each group was examined with the use of a scanning electron microscope (SEM) (n = 8), and the other half with the use of a confocal laser scanning microscope (CLSM) (n = 8). The frequency of submicrometer hiatus formation was recorded and documented with associated imaging techniques. Resin penetration within submicrometer hiati were observed in 41.7% (10/24) of SEM specimens and 83.3% (20/24) of CLSM specimens. The location and size of these structures were found to be quite uniform. Submicrometer hiati approximated 200 microm in each of the three dentin bonding systems examined. Resin penetration through submicrometer hiati does not appear to be an artifact of desiccation. These structures were clearly identified within the hybrid layer of each dentin adhesive system used in this study.     

Intracellular injection of lucifer yellow into lightly fixed cerebellar neurons

Lucifer yellow was injected intracellularly into mouse cerebellar neurons in 200 micron thick slices of tissue that had been lightly fixed by cardiac perfusion with paraformaldehyde. Direct observation of fluorescence at the time of injection established that dye diffusion was very rapid and was confined to an intracellular distribution, so that the detailed shapes of neuron cell bodies and dendrites, and some features of axons, were visualized. Different types of cerebellar neurons were identified. With sequential penetration of different neuron types near one another within a given tissue slice, synaptic relationships could be visualized. The validity of the method was tested with cells whose form and relationships are well known. The presence of axonal baskets, for example, around the somata of a row of Purkinje cells after penetration of a single basket cell axon identify cells that are related by a common inhibitory input. Once the baskets were visualized, it was possible to penetrate and fill these related postsynaptic neurons. By filling several Purkinje cells spaced along a given folium, variations in cell form can be 'correlated with' position along the changing curvature of the folium. Immature forms of cerebellar neurons could be penetrated and filled with dye in neonatal animals so that the morphology of cerebellar neurons can be compared at different stages of development.     

Effect of solvent content on resin hybridization in wet dentin bonding

With wet bonding techniques, the channels between the demineralized dentin collagen fibrils are filled with debris, solvent, and water. Commercial adhesives include solvents such as ethanol or acetone to facilitate resin-infiltration into this wet substrate. Under in vivo conditions, the solvent may be diluted because of repeated exposure of the material to the atmosphere, or concentrated because of separation of the bonding liquids into layers within the bottle. The purpose of this study was to investigate the effect of different concentrations of ethanol (10-50%) on infiltration of the adhesive resin and collagen fibril encapsulation in the adhesive/dentin interface using light microscopy, micro-Raman spectroscopy, and scanning electron microscopy. The results indicated that under wet bonding conditions the hybridization process was highly sensitive to the initial solvent concentration in the adhesive system. The staining and scanning electron microscopy results showed that the quality of the interfacial hybrid layer was poor at the lower (10%) or higher (50%) ethanol content. Micro-Raman analysis indicated that there was a distinct difference in the degree of adhesive penetration among adhesives containing different concentrations of ethanol. Adhesives containing 10 or 50% ethanol did not realize effective penetration; the penetration of the adhesive monomers increased dramatically when the initial ethanol content was 30%. The amount of solvents are essential for achieving effective bonding to dentin.     

Cell membrane labeling of Eimeria tenella sporozoites with the fluorescent dye PKH-67 GL for tracking parasite-host interactions

The fluorescent cell linker dye PKH-67 GL was used as a vital stain for sporozoites of Eimeria tenella for tests on viability, invasion of cultured primary chick kidney cells, flow cytometric analysis and fluorescence microscopy. The effect of PKH-67 GL on sporozoites was tested at a range of concentrations of dye and sporozoites. In flow cytometric analysis, 0.5-40x10(-6) M of PKH-67 GL labeled sporozoites to some degree, with the percentage of labeled sporozoites increasing with higher dye concentrations. The optimum concentration was 2x10(-6) M, allowing easy observation by fluorescence microscopy. Morphological changes in the sporozoite at concentrations greater than 5x10(-6) M were accompanied by loss of viability according to a propidium iodide inclusion assay. Sporozoite penetration of primary chick kidney cells was unaffected by the optimal level of 2x10(-6) M, allowing observation of intracellular activities. Overall, the cell linker dye greatly facilitated observation of E. tenella in vitro and in flow cytometric analysis.     

Polymerization kinetics and mechanical characterization of new formulations of light-cured dental sealants

The aim of the study was to develop and evaluate the in vitro performance of a new and simplified formulation of photocuring resin to be used as dental sealant. Two experimental dental sealants (CYTED1 and CYTED2) were formulated and their kinetic of polymerisation and physico-chemical properties were studied and compared to those of two commercially available sealants (Helioseal, Delton-FS). Rates of photoinitiated polymerisation (Rp), as well as the conversions and the quantum yields of polymerisation (phi(p)) were calculated. Flexural strength, Young's modulus, microhardness, microleakage, water sorption, and solubility were also tested. ANOVA, Student-Newman-Keuls, Pearson correlation and Kruskal-Wallis tests were used (p < 0.05). The highest Rp and phi(p) were obtained for the sealant CYTED2, Rp and phi(p) were similar for CYTEDl and Helioseal, and the lowest for Delton. Water sorption values were similar for Helioseal and CYTED2 being higher for CYTED1 and lower for Delton. No differences were found for solubility and microleakage values. Mechanical properties were better for Delton and no differences were found within the rest of the sealants. At short irradiation times (30 s), the maximum effectiveness of the photoinitiating system was obtained by the experimental CYTED2.     

Instrumentation and light dosimetry for intra-operative photodynamic therapy (PDT) of malignant brain tumours

A technique is described for uniform light irradiation of the tumour cavity after radical subtotal malignant brain tumour resection in patients whose tumours have been photosensitized by intravenous injection of hematoporphyrin derivative. The cavity is maintained by an inflatable rubber 'balloon' filled with a light-scattering liquid, within which is placed a single-strand optical fibre coupled to an argon/dye laser operating at 630 nm. Details of the construction of the applicator are given, together with measurements of the uniformity of irradiation and the light loss within the scattering medium. The device has been assessed in nine patients in a phase I trial. In two of these patients, the penetration depth of 630 nm light in brain tissue has also been measured in vivo using an optical-fibre probe, indicating that the penetration depth of 630 nm light in human brain is greater than that found in vitro.