局部应用氟化物对酸蚀釉质作用的体外研究

目的：评价局部应用氟化物对酸蚀釉质的作用。方法：收集正畸减数拔除的年轻前磨牙40个，制备釉质样本，随机分成对照组，lg／L氟化钠液组，含氟牙膏组，联合应用组。用饮料对釉质间断性酸蚀1周，然后使用不同的氟化物处理酸蚀的釉质表面1周。采用显微硬度计检测釉质表面显微硬度值（SMH），原子力显微镜（AFM）、扫描电镜（SEM）观察牙体硬组织表面的结构。结果：饮料浸泡后釉质的SMH明显下降。与对照组相比，氟化物处理后各氟化物处理组的釉质SMH均有明显增加（P＜0．001）。AFM和SEM均可见酸蚀后的釉质表面呈典型的蜂窝状结构，SEM观察显示氟化物处理后，各组釉质表面均有一定沉积物。结论：饮料会导致体外釉质表面的脱矿，氟化物能够促进体外酸蚀釉质的再矿化。     

Sodium bicarbonate solution as an anti‐erosive agent against simulated endogenous erosion

Messias DCF, Turssi CP, Hara AT, Serra MC. Sodium bicarbonate solution as an anti‐erosive agent against simulated endogenous erosion. Eur J Oral Sci 2010; 118: 385–388. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci This study investigated whether sodium bicarbonate solution, applied on enamel previously exposed to a simulated intrinsic acid, can control dental erosion. Volunteers wore palatal devices containing enamel slabs, which were exposed twice daily extra‐orally to hydrochloric acid (0.01 M, pH 2) for 2 min. Immediately afterwards, the palatal devices were re‐inserted in the mouth and volunteers rinsed their oral cavity with a sodium bicarbonate solution or deionized water for 60 s. After the washout period, the palatal devices were refilled with a new set of specimens and participants were crossed over to receive the alternate rinse solution. The surface loss and surface microhardness (SMH) of specimens were assessed. The surface loss of eroded enamel rinsed with a sodium bicarbonate solution was significantly lower than the surface loss of eroded enamel rinsed with deionized water. There were no differences between treatments with sodium bicarbonate and deionized water for SMH measurements. Regardless of the solution used as an oral rinse, eroded enamel showed lower SMH than uneroded specimens. Rinsing with a sodium bicarbonate solution after simulated endogenous erosive challenge controlled enamel surface loss but did not alter the microhardness.     

Comparing different methods to assess erosive lesion depths and progression in vitro

The aim of this study was to compare the precision and accuracy of 5 different methods applied to assess surface substance loss or changes in surface microhardness (SMH) on the same enamel surfaces after repeated acid exposures. Ground specimens from human molars were exposed to 0.01 M HCl (pH 2.2) for 6 min × 2 and measurements performed 3 times to estimate precision. The accuracies (systematic errors) were calculated against the manufacturer's calibration standard. Lesion depth progression was from 94 to 110%, related to repeated acid exposure. The precisions/accuracies were: WLI (white light interferometry), 0.5/0.4%; SP (stylus profilometry), 4.7/0.7%; OP (optical profilometry), 1.4/12%; AAS (atomic absorption spectroscopy), 0.4/17% (measured calcium loss was converted to lesion depth). The correlation between WLI and SP was R2 = 0.98, and between WLI and OP it was R2 = 0.85. SMH gave information on qualitative changes of the surface (precision: 5.5%, accuracy: 4.0%). WLI performed best in precision and accuracy, but SP, OP and AAS are all relevant methods for analysing lesion depths and progression, SMH seems suitable for analysing minor changes in surface enamel only.     

Toothbrushing after an erosive attack: will waiting avoid tooth wear?

The purpose of this study was to determine if storage for up to 4 h in human saliva results in a decrease of erosive tooth wear (ETW) and in an increase of surface microhardness (SMH) of enamel samples after an erosive attack with subsequent abrasion. Furthermore, we determined the impact of individual salivary parameters on ETW and SMH. Enamel samples were distributed into five groups: group 1 had neither erosion nor saliva treatment; groups 2–5 were treated with erosion, then group 2 was placed in a humid chamber and groups 3–5 were incubated in saliva for 30 min, 2 h, and 4 h, respectively. After erosion and saliva treatments, all groups were treated with abrasion. Surface microhardness and ETW were measured before and after erosion, incubation in saliva, and abrasion. Surface microhardness and ETW showed significant changes throughout the experiment: SMH decreased and ETW increased in groups 2–5, regardless of the length of incubation in saliva. The results of groups 3–5 (exposed to saliva) were not significantly different from those of group 2 (not exposed to saliva). Exposure of eroded enamel to saliva for up to 4 h was not able to increase SMH or reduce ETW. However, additional experiments with artificial saliva without proteins showed protection from erosive tooth wear. The recommendation to postpone toothbrushing of enamel after an erosive attack should be reconsidered.     

Combined effect of a fluoride-, stannous- and chitosan-containing toothpaste and stannous-containing rinse on the prevention of initial enamel erosion–abrasion

Objectives

The aim of this study was to assess the preventive effect of a fluoride-, stannous- and chitosan-containing (F/Sn/chitosan-) toothpaste (TP) on initial enamel erosion and abrasion.

Methods

In total, 150 human premolar enamel specimens were ground, polished and divided into 5 toothpaste/rinse groups (n = 30): (G1) placebo-TP/tap water, (G2) sodium fluoride (NaF-) TP/tap water, (G3) F/Sn/chitosan-TP/tap water, (G4) F/Sn/chitosan-TP/Sn-rinse, (G5) NaF-TP/NaF-rinse. The 8-day erosion–abrasion cyclic treatment (one cycle/day) consisted of incubating the samples in artificial saliva (30 min), then submitting the samples to toothbrush abrasion (2 min incubation in toothpaste slurry; brushing with 20 toothbrush strokes) and rinsing (2 min; 10 ml) with the respective solution: tap water (G1–G3), Sn-rinse (G4) or NaF-rinse (G5). Afterwards, the samples were submitted to erosion (2 min; 30 ml 1% citric acid, pH = 3.6). Surface microhardness (SMH) was measured initially and after every abrasion and erosion treatment. Enamel substance loss was calculated after each abrasion. Non-parametric ANOVA followed by Wilcoxon rank tests were used for analysis.

Results

G1 presented the greatest SMH decrease, while G4 presented the least SMH decrease (p < 0.001). G3 had a similar SMH decrease to G2 and G5. Substance loss was significantly lower in G4 than all other groups (p < 0.05), closely followed by G3. Both G2 and G5 showed similar calculated enamel substance loss to G1.

Conclusion

The treatment with F/Sn/chitosan-TP and tap water provided a similar SMH decrease to both NaF-TP groups, but significantly lower substance loss. F/Sn/Chitosan-TP and Sn-rinse showed a better preventive effect, which promoted less SMH decrease and reduced substance loss.

Clinical significance

The toothpaste containing fluoride, stannous and chitosan shows promising results in reducing substance loss from erosion and abrasion. The combination of this toothpaste with the stannous-containing rinse showed even better prevention against erosion–abrasion.     

Anticaries potential of a fluoride mouthrinse evaluated in vitro by validated protocols

This blind and randomized study tested in vitro, using validated protocols, the anticaries potential of an experimental fluoride mouthrinse. One-hundred enamel slabs, half sound and half with caries-like lesions (carious), all with known surface microhardness (SMH), were submitted to 3 treatment groups: A) a placebo mouthrinse (negative control); B) a positive control mouthrinse containing 0.05% NaF; and C) an experimental formulation containing 0.05% NaF and cetylpyridinium chloride as an antibacterial substance. To evaluate the formation of F products on enamel, sound (n=10) and carious (n=10) slabs were treated with the formulations during 10 min and loosely and firmly-bound F formed in enamel were determined after extraction with alkali and acid, respectively. To evaluate the inhibition of enamel demineralization, sound enamel slabs (n=10) were treated with the mouthrinse formulations 2x/day during 1 min and subjected to a pH-cycling regimen simulating a cariogenic challenge (demineralization). To evaluate enamel remineralization, the carious slabs (n=10) were submitted to the treatments 3x/day and subjected to a pH-cycling model simulating a remineralizing condition. After 8 days, enamel SMH was determined again and the percentage of SMH loss or SMH recovery was calculated for the sound and carious slabs, respectively. The experimental formulation was superior to the negative control (p<0.05) and equivalent to the positive control (p>0.05) in the formation of F products in enamel, and in the inhibition of enamel demineralization and enhancement of remineralization. These data suggest that the tested experimental fluoride mouthrinse has anticaries potential.     

氟化钠抗碳酸饮料酸蚀乳牙釉质作用的研究

目的：探讨氟化钠抗碳酸饮料对乳牙釉质酸蚀的效果。方法：用人下颌乳切牙制备72个釉质块,将其随机平均分为3组：对照组釉质块不作涂氟处理,实验组两组釉质块分别涂0.6%和1.23%浓度氟化钠;各组再按浸泡在碳酸饮料中的时间不同分成30 min和50 min两个亚组。将各组釉质块分别浸泡于碳酸饮料中30 min或50 min,取出后用去离子水冲洗,将实验组重新涂氟,然后再将釉质块浸泡在碳酸饮料中,如此循环直至12 h。用扫描电镜观察乳牙釉质表面形态改变,显微硬度计测定釉质表面硬度值（surface micro-hardness,SMH）变化,评估氟化钠保护乳牙釉质抗碳酸饮料酸蚀的效果。结果：与对照组比较,经两种浓度氟化钠处理过的乳牙釉质能不同程度地抵抗碳酸饮料的酸蚀作用,SMH值较高（P〈0.05）;随着碳酸饮料浸泡时间的延长,氟化钠保护乳牙釉质抗酸蚀的能力下降;较高浓度的氟化钠的保护效果更好,差异有统计学意义（P〈0.05）。结论：氟化钠能够增强乳牙釉质抗碳酸饮料酸蚀能力。     

三种氟化物增强乳牙釉质抵抗饮料酸蚀和再矿化作用的研究

目的观察三种氟化物处理后的乳牙釉质表面抵抗软饮料酸蚀及促进受损牙釉质再矿化的能力。方法应用显微硬度仪和扫描电镜,观测分别用NaF溶液、氟保护剂、双氟脱敏剂处理后再经饮料浸泡的乳牙釉质表面的显微硬度值(surfacemicrohardness,SMH)及形态的变化。结果饮料浸泡后,各组乳牙釉质的SMH均有明显降低;氟化物处理组的釉质SMH降低的程度明显低于对照组(P<0.001);氟保护剂和双氟脱敏剂组釉质SMH的降低无显著性差异,而低于单纯的NaF溶液组;扫描电镜可见釉质表面有不同程度的溶解。饮料侵蚀后又经氟化物再矿化的乳牙,釉质SMH明显增加,其中双氟脱敏剂组的釉质SMH增加最明显。结论釉质表面应用氟化物,能明显增强乳牙釉质抵抗软饮料酸蚀,并能促进受损牙釉质的再矿化修复能力,其中双氟脱敏剂的作用最明显。     

In vitro reduction of dental erosion by low-concentration TiF4 solutions

The aims of this study were to compare daily versus single applications of low-concentration TiF(4) solutions for reduction of enamel erosion and to evaluate the enamel surface loss due to application of these solutions. Sixty bovine enamel samples were randomly divided into 2 groups: single versus daily treatment with TiF(4) solution (ST vs. DT), which were subdivided into 5 subgroups (n = 6): 0% (control); 0.1, 0.5, 0.75 and 1% TiF(4) concentration. Fluoride treatment was performed by immersing specimens in 10 ml of the TiF(4) solutions for 5 min and rinsing them with tap water for 30 s. ST specimens were treated once only, DT specimens were treated before each erosion cycle. All specimens were subjected to 4 erosion cycles: 6 immersions of 2 min in Sprite, tap water rinse for 1 min and storage in artificial saliva for 1.5 h. Erosive enamel loss was measured using light profilometry, after each fluoride treatment and each erosive cycle. The values of surface loss/gain at application of the TiF(4) solutions did not significantly differ from zero. At the end of the 4 erosion cycles, 0.5% showed the least (ST: 3.45 ± 0.27 μm, DT: 1.08 ± 1.69 μm) and 1% showed the most surface loss (ST: 4.87 ± 1.13 μm, DT: 6.56 ± 1.49 μm). A significant reduction of surface loss was found only for 0.5% DT (p = 0.009). Within the limitations of an in vitro study, it was concluded that multiple applications of a 0.5% TiF(4) solution significantly reduced enamel erosion in vitro and caused no enamel loss at application.     

Rinsing with antacid suspension reduces hydrochloric acid-induced erosion

ObjectiveMouthrinsing with antacids, following erosive episodes, have been suggested as a preventative strategy to minimize tooth surface loss due to their neutralizing effect. The purpose of this in situ study was to evaluate the effect of an antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate in controlling simulated erosion of enamel of intrinsic origin.DesignThe experimental units were 48 slabs (3 × 3 × 2 mm) of bovine enamel, randomly divided among 12 volunteers who wore palatal appliances with two enamel slabs. One of them was exposed extra-orally twice a day to 25 mL of a hydrochloric acid (HCl) solution (0.01 M, pH 2) for 2 min. There were two independent phases, lasting 5 days each. In the first phase, according to a random scheme, half of the participants rinsed with 10 mL of antacid suspension (Gaviscon^®, Reckitt Benckiser Healthcare Ltd.), while the remainder was rinsed with deionized water, for 1 min. For the second phase, new slabs were inserted and participants switched to the treatment not received in the first stage. Therefore, the groups were as follows: (a) erosive challenge with HCl + antacid suspension; (b) erosive challenge with HCl + deionized water (DIW); (c) no erosive challenge + antacid suspension; (d) no erosive challenge + DIW. Specimens were assessed in terms of surface loss using optical profilometry and Knoop microhardness. The data were analyzed using repeated measures two-way analysis of variance and Tukey’s tests.ResultsCompared to DIW rinses, surface loss of enamel was significantly lower when using an antacid rinse following erosive challenges (p = 0.015). The Knoop microhardness of the enamel was significantly higher when the antacid rinse was used (p = 0.026).ConclusionsThe antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate, rinsed after erosive challenges of intrinsic origin, reduced enamel surface loss.     

不同波长激光活化漂白变色牙的效果评价

目的:评价不同波长激光对染色牙釉质颜色和表面显微硬度(SMH)的影响。方法:制备釉质试件75个,经染色随机分成5组(n=15),A组(对照)选用40%H2O2乳光增强漂白凝胶,漂白20 min,重复3次。B、C、D和E组:分别采用波长为445、535、810、980 nm激光照射30 s,间隔1 min,重复3次,凝胶继续保持6 min。然后,用分光光度仪分析颜色变化,显微硬度仪分析SMH变化。单因素方差分析和Tukey检验行数据分析。结果:(1)ΔE值:A组最小(P<0.05),E组最大; A相似文献   

Effect of xylitol:sorbitol on fluoride enamel demineralization reduction in situ

OBJECTIVES: To evaluate if sugar alcohols would reduce enamel demineralization enhancing the fluoride (F) effect. METHODS: A crossover in situ study was conducted in four phases, during which 10 volunteers were submitted to one of the treatments: (I) Distilled and deionized water, as a negative control; (II) F (226 microg F/ml as NaF; concentration used in commercial mouthrinse); (III) X:S (xylitol:sorbitol 1:3; final concentration 1.6M; 28% of sugar alcohols) and (IV) F+X:S (same final concentration that groups II and III). The volunteers wore palatal appliances containing four bovine enamel blocks of known surface microhardness (SMH), covered with a 'test plaque' of mutans streptococci, which were immersed during 1 min in one of the allocated treatment solutions simultaneously that the volunteers rinsed their mouths with the same solution. After the rinsing the appliances were put in the mouth and after 20 min a cariogenic challenge was made with 20% sucrose solution during 1 min. After further 45 min the 'test plaque' was collected for F analysis, enamel SMH was again determined and the percentage of change in relation to baseline was calculated; F uptake in enamel was also determined. RESULTS: With respect to all the analyses made, the group F+X:S did not differ from the F treatment (p>0.05) and the groups treated with F and F+X:S differed from the negative control (p<0.05). CONCLUSIONS: The results suggest that xylitol:sorbitol may not enhance the effect of fluoride present in mouth rinse on the reduction of enamel demineralization.     

In vitro evaluation of the erosive potential of orange juice modified by food additives in enamel and dentine

Objectives

To evaluate the erosive potential of orange juice modified by food additives in enamel and dentine.

Methods

Calcium lactate pentahydrate (CLP), xanthan gum (XG), sodium linear polyphosphate (LPP), sodium pyrophosphate tetrabasic (PP), sodium tripolyphosphate (STP) and some of their combinations were added to an orange juice. Pure orange juice and a calcium-modified juice were used as negative (C−) and positive (C+) controls, respectively. In phase 1, 15 modified orange juices were tested for erosive potential using pH-stat analysis. In phase 2, the additives alone and the combination with good results in phase 1 and in previous studies (CLP + LPP) were tested in an erosion-remineralization cycling model. In phase 3, the erosion and remineralization episodes were studied independently. Enamel was analysed by surface microhardness (SMH) and profilometry, whilst dentine by profilometry.

Results

In phase 1, reduction of the erosive potential was observed for all additives and their combinations, except XG alone. In phase 2, no detectable enamel loss was observed when CLP, LPP and CLP + LPP were added to the juice. XG, STP and PP had enamel loss similar to C− (p > 0.05). Amongst additives, the combination CLP + LPP showed the highest SMH values followed by CLP (p < 0.05). All the other groups presented SMH values similar to C− (p > 0.05). For dentine, only CLP + LPP lead to surface loss values lower than C− (p < 0.05). In phase 3, CLP, LPP and CLP + LPP seemed to protect against erosion; whilst none of the tested compounds seemed to interfere with the remineralization process.

Conclusions

CLP and LPP reduced erosion on enamel and this effect was enhanced by their combination. For dentine, only the combination CLP + LPP reduced erosion.     

Artificial enamel dental caries treated with different topical fluoride regimes: an in situ study

OBJECTIVES: To evaluate whether the topical fluoride application (acidulated phosphate fluoride, APF) at high concentration has an additional effect on the control of enamel lesions compared to fluoride dentifrice (FD; low concentration). The frequency of APF treatment on the arrestment of caries lesions and the amount of fluoride deposited on enamel after application of high and low fluoride concentrations were also evaluated. METHODS: Five subjects wore partial dentures with in vitro demineralized blocks during 35 days. All specimens (5p/subject) were brushed three times daily for 1 min with FD (1100 ppmF). Besides the FD treatment, four specimens were submitted to APF gel topical applications (12,300 ppmF) on weekly intervals (one to four applications). The enamel blocks were analyzed at baseline, after demineralization and after intraoral procedures regarding: surface roughness (SR), clinical aspects (brightness and texture), surface microhardness (SMH) and enamel fluoride content. Friedman's test was used to compare SMH and SR among the treatments. Analysis of variance, followed by Tukey's studentized range test, was used to evaluate fluoride content and SR among the groups. The significance level used was 5%. RESULTS: Changes in surface brightness, texture and SR were not detected. FD+3 APF and FD+4 APF were the only treatments capable of increasing SMH values and fluoride content compared to demineralized blocks (p < 0.001), although no differences could be observed within the treatments. CONCLUSIONS: This study showed that > or = 3 APF in addition to FD enhance enamel rehardening and produce a larger reservoir of fluoride.     

局部用奥威尔凝胶对酸性饮料导致年轻恒牙脱矿和再矿化的影响

目的比较局部使用奥威尔凝胶或氟保护漆对年轻恒牙抵抗饮料酸蚀及酸蚀后脱矿釉质再矿化的影响。方法观测年轻恒牙的釉质经饮料浸泡后再经奥威尔凝胶或氟保护漆局部处理,或奥威尔凝胶及氟保护漆处理后再经饮料浸泡的表面显微硬度（SMH）变化;应用扫描电子显微镜（SEM）观察各组釉质的表面形态。结果饮料浸泡后再经奥威尔凝胶或氟保护漆局部处理的年轻恒牙,其釉质的SMH明显增加（P<0.05）,奥威尔凝胶组的SMH高于氟保护漆组（P<0.05）。奥威尔凝胶或氟保护漆处理釉质表面后再经饮料浸泡,奥威尔凝胶组的SMH高于氟保护漆组（P<0.05）。SEM下可见各组釉质表面经饮料及奥威尔凝胶或氟保护漆处理后呈现不同程度的釉质溶解和再矿化。结论年轻恒牙釉质表面应用奥威尔凝胶可以增强釉质对饮料酸蚀的抵抗作用,促进脱矿釉质的再矿化。     

Effects of pH values of hydrogen peroxide bleaching agents on enamel surface properties

This study investigated the influence of pH values of bleaching agents on the properties of the enamel surface. Sixty freshly extracted premolars were embedded in epoxy resin and mesiodistally sectioned through the buccal aspect into two parts. The sectioned slabs were distributed among six groups (n=10) and treated using different solutions. Group HCl was treated with HCl solution (pH=3.0) and served as a positive control. Group DW, stored in distilled water (pH=7.0), served as a negative control. Four treatment groups were treated using 30% hydrogen peroxide solutions with different pH values: group HP3 (pH=3.0), group HP5 (pH=5.0), group HP7 (pH=7.0), and group HP8 (pH=8.0). The buccal slabs were subjected to spectrophotometric evaluations. Scanning electron microscopy investigation and Micro-Raman spectroscopy were used to evaluate enamel surface morphological and chemical composition alterations. pH value has a significant influence on the color changes after bleaching (p<0.001). Tukey's multiple comparisons revealed that the order of color changes was HP8, HP7>HP5, HP3>HCl>DW. No obvious morphological alterations were detected on the enamel surface in groups DW, HP7, and HP8. The enamel surface of groups HCl and HP3 showed significant alterations with an erosion appearance. No obvious chemical composition changes were detected with respect to Micro-Raman analysis. Within the limitations of this study, it was concluded that no obvious morphological or chemical composition alterations of enamel surface were detected in the neutral or alkaline bleaching solutions. Bleaching solutions with lower pH values could result in more significant erosion of enamel, which represented a slight whitening effect.     

槲皮素对牙本质抗酸蚀性能的影响

目的评价槲皮素对人牙本质抗酸蚀性能的影响,为探寻理想的牙侵蚀症预防和治疗方案提供依据。方法选择福建医科大学附属口腔医院口腔颌面外科门诊提供的因正畸需要而拔除的人第三磨牙50颗,制备牙本质试件128个,用随机数字表法将试件随机分为8组(每组16个)。各组(每组选12个试件)分别用去离子水(对照组)、无水乙醇(对照组)、12.300 mg/L氟化钠、0.120 mg/L氯己定、0.183 mg/L表没食子儿茶素没食子酸脂(epigallocatechin gallate,EGCG)和0.075、0.150、0.300 mg/L槲皮素进行处理。每天37℃下用各组相应试剂浸泡试件2 min、去离子水冲洗并静置于人工唾液2 h后,使用柠檬酸(pH=2.45)进行4次酸蚀循环;连续7 d。分别检测试件酸蚀前后的表面显微硬度及表面轮廓(计算表面硬组织丧失量),用扫描电镜观察试件表面形貌。各组剩余4个试件用10%磷酸脱矿后干燥过夜,37℃下用各组相应试剂浸泡2 min,置于人工唾液中浸提7 d,检测浸提液中Ⅰ型胶原吡啶交联终肽(cross-linked carboxyterminal telopeptide of typeⅠcollagen,ICTP)含量。结果相比对照组,氯己定、槲皮素、EGCG均可显著抑制酸蚀循环引起的牙本质表面软化和硬组织丧失,0.300 mg/L槲皮素组试件酸蚀后表面显微硬度减小率最小[(8.75±4.95)%],表面硬组织丧失量最小[(2.26±1.16)μm],ICTP含量最低[(5.72±0.88)ng],均显著低于氯己定及EGCG组(P<0.05)。各槲皮素组表面硬组织丧失量和ICTP含量差异均无统计学意义(P>0.05);0.300 mg/L槲皮素组酸蚀后表面显微硬度减小率均显著小于0.075和0.150 mg/L槲皮素组(P<0.05)。结论槲皮素可显著提高人牙本质抗酸蚀性能,其中0.300 mg/L槲皮素的作用最佳。     

The effect of gamma radiation on enamel hardness and its resistance to demineralization in vitro

Given the importance of sterilizing human teeth before using them in research, the effects of a 25 kGy dose of gamma radiation on the mechanical properties of enamel and its resistance to demineralization were evaluated. Thirty human teeth were sectioned longitudinally, and while one half of each tooth was irradiated, the other half was kept as a control. Abraded and unabraded enamel slabs were obtained from these halves. The surface microhardness (SMH) of abraded slabs of irradiated and non-irradiated enamel was determined to evaluate the effect of radiation on enamel structure. Further, both abraded and unabraded slabs, either irradiated or non-irradiated, were submitted to a pH-cycling model to evaluate enamel resistance to demineralization, which was quantified by mineral loss (deltaZ) using cross-sectional microhardness. The data for SMH and deltaZ were statistically analyzed by t-test and ANOVA, respectively. The difference in enamel SMH between slabs from irradiated teeth and non-irradiated teeth was not statistically significant (P > 0.05). The abraded enamel slabs showed higher values of deltaZ than unabraded enamel slabs (P < 0.05), but the irradiation effect was not statistically significant (P > 0.05). The results suggest that the medical gamma radiation dose of 25 kGy does not affect either enamel hardness or its resistance to demineralization.     

磷硅酸钠钙对乳牙釉质再矿化作用的研究

目的：研究生物活性材料磷硅酸钠钙（CSP）对人工脱矿的乳牙釉质表面再矿化的作用。方法：收集30颗健康离体乳磨牙,将每颗牙冠沿近远中径和颊舌径分成4个釉质块,每个釉质块随机分为4组（n ＝30）。样本经35％磷酸酸蚀2 min后分别进行如下处理：空白对照（A 组）、0．14％氟化物处理（B 组）、CSP 处理（C 组）、氟化物＋CSP 处理（D 组）,每天循环处理2次。在10、30 d 时扫描电镜观察釉质表面形态并测定釉质表面显微硬度值（SMH）。结果：扫描电镜观察显示,10 d 时A 组表面呈脱矿的蜂窝状表现,B、C 组脱矿不明显,D 组可见明显的矿化物沉积。30 d 时 A 组可见明显釉质脱矿和釉柱溶解表现,B、C 和 D 组可见程度不等的再矿化。10 d 时 D 组的 SMH 值高于 A 组（P ＜0．05）,30 d 时 B、C、D 组 SMH 值均高于 A组（P ＜0．05）,D 组 SMH 值显著高于 B 和 C 组（P ＜0．05）。结论：CSP 和氟化物具有促进乳牙釉质再矿化的作用,CSP 和氟化物联合应用优于二者的单独应用。     

The CPP-ACP relieved enamel erosion from a carbonated soft beverage: An in vitro AFM and XRD study

Objectives

To investigate the CPP-ACP's effect on enamel against carbonated beverage erosion and explore the potential mechanism.

Methods

A total of 30 enamel samples were prepared from sound bovine incisors, divided into 3 groups. Samples in the control group were kept in artificial saliva. Specimens’ surfaces were smeared with a CPP-ACP agent (Tooth Mousse, TM) for 3 min, rinsed with distilled water for 10 s, merged into cola (Coca Cola, CC) for 4 intervals of 2 min, rinsed again for the TM + CC group. In the CC group, specimens were treated solely with cola for 4 intervals (2 min each). The cycles were applied at 0, 12, 24, 36, 48 and 60 h. The surface microhardness (SMH) alterations were measured using a microhardness tester, the surface profiles were analyzed using the atomic force microscope, and the surface crystalline amount (I%) and crystallinity (FWHM) were analyzed using X-ray diffractometer.

Results

The SMH were significantly decreased in CC group, showing the largest SMH alteration; the reduction of SMH in TM + CC group was lower than that in CC group, still larger than control. After cycles, the TM + CC group showed rougher surfaces than control, while the CC group had the roughest surfaces. The TM + CC had an I% higher than the CC, and lower than the control. The TM + CC group had a FWHM lower than CC, higher than control.

Conclusions

CPP-ACP was able to relieve the erosion on enamel from carbonated beverage.