大黄提取液对脱矿釉质中钙溶出量的影响

目的 观察大黄提取液对脱矿釉质中钙溶出量的影响.方法 用不同浓度的大黄提取液和去离子水处理牙面后进行脱矿,ASCA生化分析仪对釉质脱矿后的脱矿液进行钙离子浓度的检测.结果 2 mg/ml和4 mg/ml大黄提取液处理后釉质钙溶出量<去离了水(P<0.01)、<1 mg/ml大黄提取液组(P<0.05),>2%氟化钠组但差异无统计学意义(P>0.05).1 mg/ml大黄提取液处理后釉质钙溶出量>2%氟化钠组(P<0.01),<去离子水组但差异无统计学意义(P>0.05).结论 2mg/ ml和4 mg/ml大黄提取液具有抑制脱矿釉质中钙溶出作用:2mg/ml大黄提取液为抑制钙溶出的起始有效浓度.     

不同种类饮料致离体乳牙釉质脱矿的实验研究

目的 观察不同种类饮料对离体乳牙牙釉质的显微结构变化,比较不同饮料对乳牙釉质的脱矿作用.方法 将离体乳牙分别浸泡在碳酸类、果汁类、含乳类、茶类饮料中,每5 h换液1次,持续浸泡25 h.应用扫描电镜（SEM）观察4种不同种类饮料浸泡乳牙后的牙釉质显微结构的改变,用化学分析法测定4种饮料处理乳牙后,饮料中钙、磷含量的变化.结果 4种饮料浸泡乳牙后,SEM下可见乳牙牙面呈现不同程度的破坏,出现釉柱溶解、孔隙、凹坑等脱矿现象.4种饮料均能导致乳牙釉质中钙、磷的溶出,对于钙的总溶出量,雪碧组与鲜橙多组的差异无统计学意义（P＞0.05）,但均高于其他两组,差异有统计学意义（P＜0.05）;而对于磷的总溶出量,4种饮料间的差异均有统计学意义（P＜0.05）.结论 软饮料对乳牙釉质具有脱矿作用,脱矿作用的强弱与饮料的种类有关,应当控制儿童软饮料的消耗并要关注儿童口腔健康状况.     

Raman spectroscopy for early detection and monitoring of dentin demineralization

Early detection of dental caries and variations in composition/structure of both enamel and dentin represents an important issue in modern dentistry. Demineralization has been associated to teeth discoloration, development of caries, and formation of cavities.ObjectiveIn this study, we systematically monitored the processes of demineralization/remineralization in dentin samples by means of three different spectroscopic techniques, namely, Raman spectroscopy, X-Ray Photo-electron spectroscopy (XPS), and X-Ray Diffractometry (XRD).MethodsBovine dentin samples were first exposed to acidic solutions and their structure systematically monitored as a function of time and pH. Then, the samples were rinsed in artificial saliva to simulate remineralization.ResultsThe above three spectroscopic techniques provided quantitative structural information spanning from the nanometer to the millimeter scale of sample penetration depth. An irreversible level of demineralization was reached when dentin was exposed to pH 2 beyond a time threshold of 6 h, successive treatments with artificial saliva being unable to restore the mineral fraction. On the other hand, short-term treatments at pH 5 and long-term treatments at pH 6 could partially or completely recover the dentin structure within one week of remineralization treatment.SignificanceTwo specific Raman parameters, namely, the bandwidth of the symmetric phosphate-stretching signal and the mineral-to-matrix intensity ratio, showed strong correlations with XPS and XRD data, and matched laser microscopy observations. Such correlations open the path to apply Raman spectroscopy in monitoring dentin demineralization in vivo and provide quantitative working algorithms for the prevention of oral caries.     

Sorptivity of water in enamel for categorizing caries lesions

ObjectiveThe aim of this research was to determine the association between sorptivity of water and the state of mineralization in carious enamel of different stages of severity.MethodsAs a preliminary work, water droplets of 1.5 μL were placed on the surfaces of hydroxyapatite (HA) discs of different densities. The water droplet profile was dynamically recorded every second over a period of 10 s using a contact angle meter to determine the relationship between sorptivity and density. To measure and calculate sorptivity on enamel surfaces, varnish was painted on the labial surface of 96 extracted caries-free human teeth, leaving two 1.4 ± 0.1 mm diameter circular exposed test sites. The specimens were randomly divided into 6 groups (n = 16) and subjected to 0(G0), 7(G7), 14(G14), 21(G21), 28(G28) and 35(G35) days of pH cycling, respectively. A 0.7 μL water droplet was placed on each exposed site and Optical Coherence Tomography was used to measure its height every 10 seconds for 2 min. Sorptivity was computed by considering sorption equations and Washburn's analysis of capillary kinetics and correction for evaporation was also performed. Micro-Computed Tomography scans of the specimens were obtained and delta Z (ΔZ) is the parameter used to measure mineral loss. ΔZ at 10 μm (ΔZ₁₀) and 50 μm (ΔZ₅₀) from the surface were calculated. One-way ANOVA and Post-hoc Tukey tests were used to compare sorptivity between groups and bivariate correlations were used to analyze the association between sorptivity and ΔZ.ResultsSorptivity was found to be inversely and linearly correlated with HA density with R² value of 0.95. With enamel, there is a general trend of increase in mean sorptivity from G0 to G35, except for a decrease in G21. The same trends were observed for both ΔZ₁₀ and ΔZ₅₀. The decrease in sorptivity in G21 coincided with the presence of a surface hypermineralized layer in G21 samples. Post-hoc Tukey showed significant differences in mean sorptivity between G0 and G14, G0 and G21 as well as G14 and G21. Post-hoc Dunnett’s T3 showed significant differences for ΔZ₁₀ between G0 and G14 as well as G14 and G21. Significant correlation between mean sorptivity and ΔZ₁₀ was detected with Pearson correlation coefficient of 0.461. For ΔZ₅₀, post-hoc Tukey showed significant differences between G0 and G14 but no significant difference was detected between G14 and G21. No correlations were detected between mean sorptivity and ΔZ₅₀.SignificanceSorptivity was found to be inversely and linearly correlated with HA density with R² value of 0.95. With enamel, there is a general trend of increase in mean sorptivity from G0 to G35, except for a decrease in G21. The same trends were observed for both ΔZ₁₀ and ΔZ₅₀. The decrease in sorptivity in G21 coincided with the presence of a surface hypermineralized layer in G21 samples.     

Monitoring acid-demineralization of human dentine by electrochemical impedance spectroscopy (EIS)

Objective

The purpose of this study was to monitor in situ acid-induced demineralization of dentine by using electrochemical impedance spectroscopy (EIS) and correlate the EIS findings with changes in the chemical composition and ultrastructure of dentine.

Method

EIS was used to monitor the process of demineralization of dentine induced by an acid model. Scanning electron microscopy (SEM) was used to examine the ultrastructure, while energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis were employed to investigate the changes in the chemical composition of surface dentine with demineralization.

Results

Two kinds of equivalent circuits that matched the histological structure of dentine were used to fit the EIS data. The parameters R_d, which is the resistance of the bulk of dentine layer and R_ct, which is the charge transfer associated with the penetration of electrolyte into the dentinal tubules, decreased with increasing duration of demineralization. SEM images showed that the smear layer on the dentine and peritubular dentine disappeared with demineralization. The EDX results showed that the content of calcium and phosphorus decreased consistently with the decreasing content of HAP as shown by the XRD results. The findings from this study suggested that the changes in R_d and R_ct determined by the EIS corresponded well with the variation in structure and composition of dentine.

Conclusions

EIS could be employed to monitor structural and chemical compositional changes induced by acid-demineralization on dentine surface.     

Comparison of the remineralization potential of CPP-ACP and CPP-ACP with 900 ppm fluoride on eroded human enamel: An in situ study

Objective

The aim of this in situ study was to compare the remineralization potential of pastes containing CPP-ACP and CPP-ACP with 900 ppm fluoride on human enamel softened by a cola drink.

Design

Forty-five enamel specimens obtained from human third molar teeth were eroded in a cola drink for 8 min and then attached to intra-oral devices worn by five volunteers. The specimens were subjected to three different in situ remineralization protocols using: (1) CPP-ACP (Group I), (2) CPP-ACP with 900 ppm fluoride (Group II), and (3) saliva (Group III, control). Vickers microhardness measurements were obtained at baseline followed by demineralization and remineralization stages.

Results

The CPP-ACP, CPP-ACP with 900 ppm fluoride and saliva controls resulted in 46.24%, 64.25% and 2.98% increase in post-erosion microhardness values, respectively. One-way ANOVA revealed statistically significant differences in the mean microhardness values between pastes containing CPP-ACP and CPP-ACP with 900 ppm fluoride.

Conclusions

Both CPP-ACP and CPP-ACP with 900 ppm fluoride substantially remineralized the softened enamel, with the CPP-ACP and fluoride combination showing higher remineralization potential than CPP-ACP. This study confirmed the synergistic effect of fluoride with CPP-ACP on remineralization of eroded enamel.     

含氟牙膏对正畸治疗中脱矿牙釉质显微硬度干预作用的体外实验研究

目的观察含氟牙膏在模拟口腔环境下对脱矿牙釉质显微硬度的干预作用。方法选取正畸治疗拔除的离体牙16颗。随机分为对照组和实验组,每组各8颗。实验组样本采用含氟牙膏处理,对照组采用无氟牙膏处理。采用显微硬度计分别测定两组牙齿脱矿前后、唾液浸泡后及再矿化后的牙釉质表面显微硬度,并行组间比较分析。结果实验组再矿化后牙釉质显微硬度值[（200．5±21．3）KHN]显著高于对照组[（143．4±18．8）KHN]（P〈0．01）,而脱矿前后及唾液浸泡后两组间牙釉质表面显微硬度并无明显差异（P〉0．05）.结论在模拟口腔环境的离体牙体外实验中,含氟牙膏能够有效提高脱矿牙釉质的显微硬度值。     

EFFECT OF FLUORIDATED VARNISH AND SILVER DIAMINE FLUORIDE SOLUTION ON ENAMEL DEMINERALIZATION: pH-CYCLING STUDY

Objective:

In the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated.

Methods:

Bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (C), varnish (V) and diamine silver fluoride solution (D). The blocks were submitted to pH cycles in an oven at 37°C. Next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%SML) and the mineral loss (∆Z). The fluoride present in enamel was also determined.

Results:

F/Px10^-3(ANOVA, p<0.05) in the 1^stlayer of enamel before pH-cycling were (C, V and D): 1.61^a; 21.59^band 3.98^c. The %SMH (Kruskal-Wallis, p<0.05) were: - 64.0^a, -45.2^band -53.1^c. %∆Z values (ANOVA, p<0.05) were: -18.7^a, -7.7^band -17.3^a.

Conclusion:

The data suggested that the fluoride released by varnish showed greater interaction with sound enamel and provided less mineral loss when compared with silver diamine solution.     

Duraphat与Fluor Protector抑制固定正畸矫治中牙釉质脱矿的比较研究

目的　使用激光龋齿探测仪,比较两种含氟物Duraphat与Fluor Protector抑制固定正畸矫治中牙釉质脱矿的临床效果。方法　选取接受直丝弓固定矫治的12-18岁青少年患者60例,其中男性23例,女性37例,平均年龄14.8岁。采用自身对照法,实验组A右上前牙及前磨牙涂布Fluor Protector,实验组B左下前牙及前磨牙涂布Duraphat,对照组A左上前牙及前磨牙不使用任何药物,对照组B右下前牙及前磨牙仅涂布0.9%的氯化钠水溶液。分别于患者粘接正畸托槽之前时、粘接托槽后1个月、粘接托槽后3个月使用DIAG-Noden激光龋齿检测仪测试受试牙牙面并记录数值,应用单因素方差分析比较各组数值是否有统计学差异。结果 （1）正畸托槽粘接后1个月、3个月时,2组涂布氟漆的实验组的DD值均低于2组未涂布氟漆的对照组（P<0.05）,说明Duraphat与Fluor Protector两种氟漆均显示了明显抑制釉质脱矿的能力。（2）正畸托槽粘接后1个月、3个月时,涂布Flour Protector的实验组A的DD值与涂布Duraphat的实验组B的DD值间比较差异无统计学意义（P>0.05）,说明两种不同浓度的氟保护漆在抑制牙釉质脱矿的能力方面没有明显优劣。结论　（1）接受固定矫治的患者存在釉质脱矿的易感性。（2）Duraphat与Fluor Protector两种不同浓度的氟化物对于正畸过程中牙釉质的脱矿均有抑制作用,二者抑制脱矿的能力没有明显差异。（3）DIAGNodent激光龋齿检测仪适合临床探查釉质的脱矿及龋损,对釉质表面的改变感应相当敏锐,帮助医师对龋病做出早期诊断,及早监控并采取合适的措施。     

The relevance of controlled fluoride release with bonded orthodontic appliances

The aim of this investigation was to study the inhibitory effect of fluoride-releasing adhesives on in vitro demineralization of uncovered enamel adjacent to a bonded orthodontic bracket. Bovine enamel, a glass-ionomer cement and a Bis GMA-based adhesive were used. Metal brackets were bonded to intact and acid-etched enamel, following this a number of the samples received an acidified fluoride (APF) application. Each sample was subjected to demineralization treatment in vitro, and subsequently sectioned and microscopically investigated for the formation of artificial caries.

It is concluded that the fluoride-releasing glass-ionomer cement protected a substantial area of uncovered enamel adjacent to the cemented bracket. The opposite effect was observed for the Bis GMA adhesive. The artificial caries developed not only in the uncovered enamel, but also, to some extent, under the adhesive material. Topical fluoridation did not affect the results significantly.