Effectiveness of plant-derived proanthocyanidins on demineralization on enamel and dentin under artificial cariogenic challenge

Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries.

Objective

The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin.

Material and Methods

Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride – 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy.

Results

The means were subjected to statistical analysis using the ANOVA and Fisher’s PLSD tests (p<0.05). For enamel SH, GF showed the highest hardness values. In the dentin, GF was also the one that showed higher hardness values, followed by GSE. Regarding the cross-sectional hardness values, all groups behaved similarly in both the enamel and dentin. The samples that were treated with GSE and fluoride (GF) showed statistically higher values than the control.

Conclusion

Based on the data obtained in this in vitro study, it is suggested that grape seed extract inhibits demineralization of artificial carious lesions in both the enamel and dentin, but in a different scale in each structure and in a smaller scale when compared to fluoride.     

Response of pulp cells to resin infiltration of enamel white spot-like lesions

ObjectivesTo investigate the trans-enamel and trans-dentinal biological effects of treating enamel white spot-like lesions (EWSLs) with resin infiltration components (RICs) on odontoblast-like cells (MDPC-23) and human dental pulp cells (HDPCs).MethodsEWSLs were induced in 60 enamel/dentin discs (4.0 ± 0.2 mm thick) using S. mutans. The discs were adapted into artificial pulp chambers and MDPC-23 were seeded on the dentin surface. The components of a resin infiltration system (Icon) were applied individually or in combination on the enamel surface as following (n = 10/treatment): Etch, Infiltrant, Etch+Infiltrant, or Etch+Dry+Infiltrant. The application of water or hydrogen peroxide served as negative and positive controls, respectively. After 72 h, MDPC-23 viability was evaluated. The extracts were exposed for 72 h to pre-cultured MDPC-23 and HDPCs in 96-well plates to evaluate cell viability, alkaline phosphatase activity (ALP), mineralized nodule formation (MN), and the expression of inflammatory cytokines (ICs) and mineralization-related genes (MRs). Data were analyzed by ANOVA complemented with Tukey or Games-Howell post-hocs (α = 5%).ResultsCell viability, ALP activity, and MN formation were significantly reduced in response to the RICs, presenting intermediate values compared to positive and negative controls. Likewise, ICs were upregulated, whereas MRs were downregulated. Among the RICs, the Etch component caused the most notorious detrimental effects.SignificanceResin infiltration of EWSLs negatively affected the metabolism of pulp cells in vitro. Therefore, even though resin infiltration is a micro-invasive therapy for non-cavitated caries in enamel, it should be closely followed up seen that components may diffuse and unbalance pulp homeostasis.     

The effect of casein phosphopeptide-amorphous calcium phosphate on remineralization of artificial caries-like lesions: an in vitro study

BACKGROUND: The aims of this study were to investigate the efficacy of CPP-ACP containing Tooth Mousse on the remineralization of enamel lesions and to compare its efficacy to that of a fluoride-containing toothpaste. METHODS: Permanent teeth were placed in demineralizing solution for 96 hours to produce artificial caries-like lesions 120-200 microm in depth. They were sectioned into 100-150 microm thick samples and randomly assigned to five groups: for Group A, a fluoridated toothpaste (1100 ppm) was used as a positive control and in Group B, a non-fluoridated toothpaste was used as a negative control. Tooth Mousse containing CPP-ACP was tested by three different means: as a toothpaste (Group C); as a topical coating (Group D); and (Group E) as a topical coating after treating the sections with the same fluoridated toothpaste as in Group A. RESULTS: The lesion depth decreased significantly by 7 per cent in Group A, 10.1 per cent in Groups C and D, and 13.1 per cent in Group E (Paired t- test, p < 0.05), while in Group B the lesion depth increased significantly by 23 per cent. CONCLUSIONS: Based on the data obtained, CPP-ACP containing Tooth Mousse remineralized initial enamel lesions and it showed a higher remineralizing potential when applied as a topical coating after the use of a fluoridated toothpaste.     

Remineralization effects of gum arabic on caries-like enamel lesions

OBJECTIVE: Gum arabic is a natural polysaccharide exudate from Acacia senegal and other related African species of Acacia. Gum arabic is considered to have an ability to enhance remineralization, because of its high concentration of Ca(2+). However, the caries preventive capacity of gum arabic has been scarcely investigated. We evaluated the cariostatic activities of gum arabic using histopathological methods to determine its effects on remineralization. DESIGN: Following incubation in demineralization solution, human third molars were exposed to 10 mg/ml of gum arabic, sodium fluoride at 1000 ppm (NaF), or double distilled water (DW, negative control), then subjected to demineralization-remineralization cycles. Before and after demineralization-remineralization cycles, contact microradiographs of each sample were taken and mineral distribution quantities were calculated. RESULTS: The remineralization ratio of the molars exposed to gum arabic was similar to that of those exposed to NaF, while the ratios of both were significantly greater than that of those exposed to DW. CONCLUSIONS: Gum arabic enhanced the remineralization of caries-like enamel lesions in vitro, suggesting its inhibitory effects towards dental caries.     

Shear bond strength of orthodontic brackets to enamel after application of a caries infiltrant

Objective:To examine differences in the shear bond strength of orthodontic brackets on differently mineralized enamel surfaces after applying a caries infiltrant or conventional adhesive.Materials and Methods:A total of 320 bovine incisors were assigned to eight pretreated groups, and the shear force required for debonding was recorded. Residual adhesive was evaluated by light microscopy using the adhesive remnant index. Statistical analysis included Kolmogorov-Smirnov, analysis of variance (ANOVA), and Scheffé tests.Results:The highest bond strength (18.8 ± 4.4 MPa) was obtained after use of the caries infiltrant. More residual adhesive and fewer enamel defects were observed on infiltrated enamel surfaces. Brackets on demineralized enamel produced multiple enamel defects.Conclusions:Acceptable bond strengths were obtained with all material combinations. A caries-infiltrant applied before bracket fixation has a protective effect, especially on demineralized enamel.     

Potential agents to control enamel caries-like lesions

Objectives

To assess whether pastes containing casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) and calcium sodium phosphosilicate (CSP) control artificial caries lesion progression.

Methods

Enamel slabs of bovine teeth were embedded in polyester resin and had their enamel surfaces serially polished, and tested for surface microhardness (SMH, 25 g, 5 s). Incipient caries-like lesions were pre-formed and specimens were evaluated by microhardness test (SMH_post-lesion) and randomly assigned to five treatment groups (n = 15): (1) regular dentifrice (RE, 1,100 ppm F); (2) dentifrice with calcium sodium phosphosilicate (CSP); (3) amorphous calcium phosphate stabilized by casein phosphopeptide (CPP–ACP); (4) CPP–ACP with 900 ppm F (CPP–ACP + F) and (5) control group—unexposed to any remineralizing agent. Treatments were applied five times, after the de-remineralization period in the cariogenic challenges. Post-treatments SMH measurements were conducted (SMH_{post-treatment}).

Results

ANOVA was applied for data evaluation and revealed a significant difference among the treatments (p = 0.0161). Tukey's test was conducted and the percentage of mineral loss was calculated. Specimens exposed to CSP (7.1%), RE (6.7%) and CPP–ACP + F (3.8%) showed lower mineral loss than those that in the control group (−11.0%). CPP–ACP group (3.2%) differed from the control, CSP and RE groups.

Conclusions

Depending on the agent used, a remineralizing effect may be expected, which reflects in caries lesions progression.     

不同方向剪切力作用下两种树脂粘结剂与人牙釉质的剪切粘结强度研究

目的：考察不同施力方向上树脂粘结剂与人牙釉质的剪切粘结强度。方法：使用树脂类粘结剂A（Clearfil SE BOND）和B（Prime＆Bond NT），将各自配套的复合树脂粘结在离体人牙釉质面上，当剪切力沿根尖、骀面、近中和远中方向作用时测量其剪切粘结强度。结果：粘结剂A和B与牙釉质的剪切粘结强度值显示，根尖方向[分别为（44．38±3．68）Pa和（45．50±2．88）Pa]〉近中方向[分别为（37．81±7．56）Pa和（40．15±2．59）Pa]和远中方向[分别为（35．71±3．34）Pa和（35．75±4．15）Pa]〉[牙合]面方向[分别为（29．19±3．75）Pa和（33．44±3．79）Pa]，近中方向和远中方向间差异无统计学意义（P〉0．05），根尖方向与[牙合]面方向间差异有统计学意义（P〈0．05）。结论：树脂粘结剂与人牙釉质剪切粘结强度的大小与剪切力作用的方向相关。     

渗透树脂治疗乳牙釉质早期龋的体外研究

目的：探讨渗透树脂治疗人工脱矿乳牙釉质早期龋对其釉质显微硬度的影响。方法：选取5～7岁儿童因滞留拔除的无龋下颌乳中切牙21颗,制备人工脱矿釉质模型后,随机将其分为空白对照组、脱矿组、渗透树脂治疗组,每组7个样本,采用显微硬度测试仪测量各组牙釉质显微硬度,观察釉质显微硬度的变化。结果：空白对照组、渗透树脂治疗组牙釉质表面显微硬度明显高于脱矿组,差异具有统计学意义（P＜0．01）;渗透树脂治疗组显微硬度低于空白对照组,差异具有统计学意义（P＜0．01）。结论：乳牙釉质脱矿后牙釉质表面显微硬度降低,渗透树脂治疗釉质脱矿可提高牙釉质表面的显微硬度。     

五倍子原液和中性液促进牙釉质人工龋再矿化作用的比较

目的 比较五倍子原液、中性液促进牙釉质人工龋的再矿化作用,探讨五倍子药液pH调节对其促进釉质龋再矿化作用的影响.方法 制备牛牙釉质人工龋标本,配制五倍子多酚化合物原液(pH 3.8)和五倍子多酚化合物中性液(pH 7.0).体外pH循环条件下分别使用NaF(NaF组)、去离子水(去离子水组)、五倍子多酚化合物原液(pH 3.8五倍子组)及中性液(pH 7.0五倍子组)处理龋标本.原子力显微镜下观察pH循环前、后各组标本再矿化层的形貌特点.显微放射照相检测pH循环前后标本的矿物丢失量及龋损深度.结果 pH循环后,原子力显微镜下两个五倍子组牙釉质表面均有明显的不规则突起物,在不规则排列、边界模糊的晶体表面散在分布了大量的颗粒.显微照相检测到NaF组、去离子水组、pH 3.8五倍子组、pH 7.0五倍子组样本的矿物丢失量变化百分率分别为(-38±14)%、(+43±7)%、(-10±4)%和(-11±4)%;龋损深度变化百分率分别为(-27.79±3.51)%、(+21.13±2.83)%、(-8.43±3.32)%和(-9.20±3.89)%,两个五倍子组均表现出整体矿物丢失和龋损深度减小,两组间整体矿物丢失量变化百分率和龋损深度变化百分率差异无统计学意义(P＞0.05).结论 五倍子原液与中性液促进早期釉质龋的再矿化作用无明显差异,五倍子药液pH调节对其促进再矿化作用无明显影响,用药过程中无需将瓦倍子原液调节至中性.

Abstract：

Objective To compare the effect of original and neutral G alla chinensis in promoting the remineralization of initial enamel carious lesions in vitro and to investigate the influence of Galla chinensiswith different pH on the promoting effect. Methods Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then the lesions were exposed to a pH-cycling regime for 12 days.Each daily cycle included 4 × 1 min application of one of four treatments: distilled and deionized water (DDW), aqueous solutions of NaF, acidic or neutral aqueous solutions of Galla chinensis extract(GCE). Before and after pH-cycling, the surface topography of the enamel slabs was observed by atomic force microscopy( AFM), and the integrated mineral loss and lesion depth of all the specimens were analysed by transverse mieroradiography. Results AFM images revealed the surface topographical changes of GCE- treated enamel. The percentage change of integrated mineral loss ( △IML% ) of the samples of NaF group,DDW group, pH 3.8 GCE group and pH 7.0 GCE group was ( -38 ± 14)%, ( + 43 ± 7 )%, ( - 10 ± 4)% and ( - 11 ± 4)% respectively. The percentage of lesion depth (△LD%) of the samples of NaF group,DDW group, pH 3.8 GCE group and pH 7.0 GCE group was( -27.79 ±3.51 )%, ( +21.13 ±2. 83)%,( -8.43 ± 3.32)% and ( -9.20 ± 3.89)% respectively. There was no significant difference in △IML%and △LD% between pH 3. 8 and pH 7. 0 GCE-treated enamel. Conclusions There is no significant difference in enhancement of remineralization of initial enamel carious lesions between the original and neutral Galla chinensis. Different pH Galla chinensis does not have obvious influence on remineralization. It is unnecessary to regulate the pH value of queous solution of Galla chinensis extract which acts as a anticaries agent.     

In vitro quantitative light-induced fluorescence to measure changes in enamel mineralization

A sensitive, quantitative method for investigating changes in enamel mineralization of specimens subjected to in vitro or in situ experimentation is presented. The fluorescence-detecting instrument integrates a Xenon arc light source and an object positioning stage, which makes it particularly suitable for the nondestructive assessment of demineralized or remineralized enamel. We demonstrate the ability of in vitro quantitative light-induced fluorescence (QLF) to quantify changes in mineralization of bovine enamel discs that had been exposed in vitro to a demineralizing gel (n=36) or biofilm-mediated demineralization challenges (n=10), or were carried in situ by three volunteers during a 10-day experiment (n=12). Further experiments show the technique's value for monitoring the extent of remineralization in 36 specimens exposed in vitro to oral multispecies biofilms and document the repeatability of in vitro QLF measurements (n=10) under standardized assay conditions. The validity of the method is illustrated by comparison with transversal microradiography (TMR), the invasive current gold standard for assessing experimental changes in enamel mineralization. Ten discs with 22 measurement areas for comparison demonstrated a positive correlation between TMR and QLF (r=0.82). Filling a technological gap, this QLF system is a promising tool to assay in vitro nondestructively localized changes in mineralization of enamel specimens.     

In vitro assessment of artificial saliva formulations on initial enamel erosion remineralization

Objectives

Various formulations of artificial saliva are present in the literature and little guidance is available on the standardization of type of saliva for use in in vitro protocols for erosive studies. The aim of this study was to evaluate the remineralizing capacity of different formulations of artificial saliva on initial enamel erosive lesion.

Methods

Bovine enamel blocks were subjected to short-term acidic exposure by immersion in citric acid 0.05 M (pH 2.5) for 15 s, resulting in surface softening without tissue loss. Then 90 selected eroded enamel blocks were randomly and equally divided into 6 groups according to saliva formulation (n = 15): Saliva 1 (contain mucin); Saliva 2 (Saliva 1 without mucin); Saliva 3; Saliva 4; Saliva 5 (contain sodium carboxymethyl cellulose) and control (C) (deionized water). After demineralization enamel blocks were subjected to remineralization by immersion in the saliva's formulations for 2 h. Enamel remineralization was measured by superficial hardness test (% superficial hardness change). The data were tested using ANOVA and Tukey's test (p < 0.05).

Results

All the tested formulations of artificial saliva resulted in significantly higher enamel remineralization compared to control (p < 0.001). Saliva 3 showed higher percentage of enamel remineralization than Saliva 5 (p < 0.05).

Conclusions

Besides the variety of artificial saliva for erosion in vitro protocols, all the formulations tested were able to partially remineralize initial erosive lesions.     

Chitosan effect on dental enamel de-remineralization: An in vitro evaluation

Objectives

The aim of this work was to evaluate the in vitro effect of chitosan (concentration and time of action) treatment on enamel de-remineralization behavior upon a pH cycling assay.

Methods

Different group of human tooth samples were exposed to de-remineralizing solutions of controlled pH using a random experimental design. Microhardness and phosphorus chemical analysis were employed to evaluate the loss of phosphorus from the samples. Optical coherence tomography (OCT) images were obtained for selected specimens in order to evaluate the degree of penetration of chitosan into enamel.

Results

Vickers microhardness results were higher for samples treated with chitosan for concentration between 2.5 mg/mL and 5.0 mg/mL and time of action between 60 s and 90 s. A maximum inhibition of mineral loss of 81% was obtained. Chemical analysis indicated lower net pohosphorus loss (net P loss) for samples treated with chitosan. Best results were obtained in the same conditions found out with microhardness measurements. Chitosan had little effect on the remineralization process. OCT results indicated a correlation of chitosan penetration with chitosan concentration. For chitosan concentrations of 2.5 g/mL and 5.0 g/mL the penetration was up to the dentin–enamel junction.

Conclusions

Chitosan interferes with the process of demineralization of the tooth enamel inhibiting the release of phosphorus in this laboratory study. Demineralization is influenced by the concentration and exposure time of the biopolymer to the enamel. Microhardness measurements may be used as an indication of mineral loss from tooth enamel. Additionally, OCT images support the idea that chitosan may act as a barrier against acid penetration, contributing to its demineralization inhibition.     

渗透树脂和多乐氟处理脱矿釉质后的抗酸性和再矿化能力比较

目的 通过观察渗透树脂与多乐氟处理脱矿釉质后其牙齿表面显微硬度和粗糙度的变化,对两种材料在釉质抗酸性和再矿化能力方面的性能进行评估。方法 选择正畸拔除的健康前磨牙48颗,建立釉质表面脱矿模型,按照不同材料的处理条件随机分为4组,A（不做任何处理）,B（渗透树脂）,C（多乐氟）;D（渗透树脂+多乐氟）,分别经脱矿液组（1d,3d）和再矿化液组（7d）浸泡处理后,测定牙齿表面的显微硬度和粗糙度。结果 不同材料处理脱矿模型后即刻,B、D组的显微硬度、粗糙度均明显增加（P<0.001）,B、D组之间无统计学差异（P>0.05）;而C组显微硬度、粗糙度均明显减低（P<0.001）。继续脱矿（1d,3d）后,各组的显微硬度均下降,而粗糙度却明显增加;再矿化7d后,A、C组显微硬度和粗糙度均显著增加（P<0.001）,B、D组增加不明显（P>0.05）。结论 渗透树脂具有良好的改善牙齿表面硬度的作用,但在抗酸性和促进牙齿再矿化方面无明显优势。而氟化物则在抗酸性和促进再矿化方面有突出表现。当两者联合应用时,可以起到较好协同作用,明显增强牙齿的硬度、抗酸性和再矿化性能。     

ICON渗透树脂修复人工釉质龋白斑的效果研究

目的：评价ICON渗透树脂修复人工釉质龋白斑的效果。方法：选取因正畸而拔除的前磨牙28颗,制备人工釉质龋后,随机分为实验组和对照组,实验组采用ICON渗透树脂修复人工釉质龋白斑,对照组采用涂氟处理,测量并比较釉质龋白斑修复后的表面微硬度和龋白斑面积减少百分比,最后采用SPSS17．0软件进行统计分析。结果：治疗修复后实验组釉质龋的表面微硬度值显著高于对照组,差异具有统计学意义（P＜0．05）;修复后实验组龋白斑所占面积百分比低于对照组,差异具有统计学意义（P＜0．05）。结论：ICON渗透树脂能提高人工釉质龋白斑表面的微硬度,并能大大降低龋白斑的面积百分比,推荐临床使用。     

Effect of low-fluoride toothpastes combined with hexametaphosphate on in vitro enamel demineralization

Objectives

The aim of this study was to evaluate the anticaries effect of low-fluoride toothpastes combined with hexametaphosphate (HMP) on enamel demineralization.

Methods

Bovine enamel blocks were subjected to pH cycling and treatment with toothpaste's slurries (15 groups; 2×/day). Toothpaste mixtures contained the following: no fluoride (F) plus HMP (from 0 to 3.0%); 250 ppm F plus HMP (from 0 to 3.0%); 500 ppm F; 1100 ppm F; and a commercial toothpaste (1100 ppm F). After pH cycling, surface and cross-sectional hardness, as well as F present in the enamel were determined. The demineralization depth was analyzed using polarized light microscopy. The variables were subjected to 1-way ANOVA, followed by Student–Newman–Keuls’ test (p < 0.05).

Results

In the absence of fluoride, 0.5% HMP promoted the lowest mineral loss and its effect was similar to that of a 250 ppm F toothpaste (p > 0.05). The combination of 0.5% HMP and 250 ppm F resulted in lower mineral loss (p < 0.05) and similar lesion depth when compared to the 1100 ppm F toothpaste (p > 0.05).

Conclusion

To conclude, the combination of 0.5% HMP and 250 ppm fluoride in a toothpaste has a similar inhibitory effect on enamel demineralization in vitro when compared to a toothpaste containing 1100 ppm F.

Clinical significance

The anticaries effect of toothpaste containing 250 ppm F combined with 0.5% HMP was similar to that of a 1100 ppm F toothpaste, despite the 4-fold difference in F concentration. Although such effects still need to be demonstrated in clinical studies, it may be a viable alternative for preschool children.     

Effect of iron on bovine enamel and on the composition of the dental biofilm formed "in situ"

OBJECTIVES: This study investigated in situ the effect of iron (Fe) on the reduction of demineralization of bovine enamel, as well as on the composition of dental biofilm. DESIGN AND METHODS: Twelve volunteers were included in this blind crossover study, which was conducted in two stages of 14 days each. For each stage, the volunteers received palatal appliances containing four blocks of bovine enamel (4 mm x4 mm x 2.5 mm). Six volunteers dripped a solution of 15 mmol L(-1) ferrous sulphate onto the fragments and the remaining six dripped deionized water (eight times per day). After five minutes, a fresh 20% (w/v) sucrose solution was dripped onto all enamel blocks. During the experimental period the volunteers brushed their teeth with non-fluoridated dentifrice. After each stage, the percentage of surface microhardness change (%SMHC) and area of mineral loss (DeltaZ) were determined on enamel and the dental biofilm formed on the blocks was collected and analysed for F, P, Ca, Fe and alkali-soluble carbohydrates. The concentrations of F, Ca and Fe in enamel were also analysed after acid biopsies. RESULTS: There was a statistically significant increase in the P and Fe concentrations in the biofilms treated with ferrous sulphate (p<0.05), which was not observed for F, Ca and alkali-soluble carbohydrates. The group treated with ferrous sulphate had significantly lower %SMHC and DeltaZ when compared to control (p<0.05). CONCLUSIONS: These results showed that ferrous sulphate reduced the demineralization of enamel blocks and altered the ionic composition of the dental biofilm formed in situ.     

Effect of fluoride on artificial caries lesion progression and repair in human enamel: regulation of mineral deposition and dissolution under in vivo-like conditions

OBJECTIVE: This study was carried out to determine in vitro the effect of fluoride on (1) the demineralization of sound human enamel and (2) the progression of artificial caries-like lesions, under relevant oral conditions. METHODS: Thin sections of sound human enamel were exposed to solutions undersaturated with respect to tooth enamel to a degree similar to that found in dental plaque fluid following sucrose exposure in vivo, containing fluoride concentrations (0-0.38ppm) found in plaque fluid. Mineral changes were monitored for 98 days, using quantitative microradiography. The effect of fluoride (1.0-25.0ppm) on the progression of artificial caries-like lesions was similarly studied. RESULTS: Fluoride concentrations of 0.19ppm and greater were found to prevent the demineralization of sound enamel in vitro. However, significantly higher concentrations of fluoride (25.0ppm) were required to prevent further demineralization of artificial caries-like lesions. Demineralizing solutions with intermediate fluoride concentrations (2.1-10.1ppm) induced simultaneously remineralization in the outer portion of the lesion and demineralization in the inner portion. Simultaneous remineralization and demineralization were also observed in hydroxyapatite pellets. CONCLUSIONS: Our results show that the observed effect of fluoride on enamel demineralization is not solely a function of bulk solution properties, but also depends on the caries-status of the enamel surface. A mechanistic model presented indicates that, in comparison to sound enamel surfaces, higher concentrations of fluoride are required to prevent the progression of artificial caries-like lesions under in vivo-like conditions since the diffusion of mineral ions that promote remineralization is rate-limiting.