Erosive Challenge Research Articles

In situ effect of a proanthocyanidin mouthrinse on dentin subjected to erosion.

Proanthocyanidin has been shown to be efficient in inhibiting matrix metalloproteinases. The aim of this in situ study was to evaluate the protective effect of Proanthocyanidin-based mouthrinses either with naturally acidic or with a neutral pH applied on dentin subjected to erosion. Eight volunteers wore one palatal device in two phases (7 days washout) with 16 samples per group (n=8). The groups under study were: First Phase/ G1 - 10% proanthocyanidin mouthrinse (pH 7.0, Experimental group 1 - Purified Grape Seeds Oligomeric Proanthocyanidins), G2 - 10% proanthocyanidin mouthrinse (pH 3.0, Experimental group 2 - Purified Grape Seeds Oligomeric Proanthocyanidins). Second Phase/ G3 - 0.12% chlorhexidine mouthrinse (pH 7.0, Positive control group), G4 - no previous treatment (Negative control group). Each device was subjected to 3 erosive cycles (5 minutes) per day for 5 days. Treatments with different mouthrinses were applied once after the second erosive challenge (5 minutes). Profilometry was used to quantify dentin loss (µm). Data were analyzed by repeated measures of ANOVA followed by Fisher's test (p<0.05). G1 (1.17±0.69) and G3 (1.22±0.25) showed significantly lower wear values with no statistical difference between them. G2 (2.99±1.15) and G4 (2.29±1.13) presented higher wear values with no significant differences between them. The 10% proanthocyanidin mouthrinse (pH 7.0) could be a good strategy to reduce dentin wear progression.

The use of a new calcium mesoporous silica nanoparticle versus calcium and/or fluoride products in reducing the progression of dental erosion.

Objective There is increasingly common the consumption more times a day of foods and acidic drinks in the diet of the population. The present study aimed to evaluate and compare the effects of a calcium mesoporous silica nanoparticle single application of other calcium and/or fluoride products in reducing the progression of dental erosion.Methodology Half of the eroded area was covered of 60 blocks of enamel, after which the block was submitted to the following treatments: (Ca2+-MSN), casein phosphopeptide–amorphous calcium phosphate (CPP-ACP); CPP-ACP/F-(900 ppm F−); titanium tetrafluoride (TiF4 1%) (positive control); sodium fluoride (NaF 1.36%) (positive control); and Milli-Q® water (negative control) before being submitted to a second erosive challenge. A surface analysis was performed via a three-dimensional (3D) noncontact optical profilometry to assess the volumetric roughness (Sa) and tooth structure loss (TSL) and and through scanning electron microscopy (MEV). An analysis of variance (ANOVA) and Tukey’s test were performed.Results Regarding Sa, all experimental groups exhibited less roughness than the control (p<0.05). The TSL analysis revealed that the Ca2+-MSN and NaF groups were similar (p>0.05) and more effective in minimizing tooth loss compared with the other groups (p<0.05).Conclusions The Ca2+-MSN and NaF treatments were superior compared with the others and the negative control.

Canada’s Experience with the ICAP

As tax administrations around the world continue to reform international tax rules to promote transparency and address the challenges of aggressive tax avoidance, base erosion and profit shifting, and the digitalisation of the economy, multinational taxpayers are increasingly expressing concerns about a rise in compliance costs and risks of double taxation. To tackle these issues, Canada has, in the past years, implemented a series of administrative policies and initiatives of voluntary co-operation, aimed at increasing disclosure by large corporations for better compliance, while reducing risks. This chapter, developed by consultation with competent authorities from Canada Revenue Agency’s International and Large Business Directorate, focuses on Canada's involvement in the OECD’s new pilot project for co-operative compliance: the International Compliance Assurance Programme (ICAP). It concludes that one of the ICAP's impacts will be to allow states to gain insight into the approaches, and anticipate the likely revenue positions, of their peers.

Effect of different citrus sweets on the development of enamel erosion in vitro.

The increased consumption of citrus sweets can contribute to the development of erosive tooth wear (ETW).ObjectiveThis in vitro study evaluated the erosive potential of citrus sweets on bovine enamel samples regarding the quantification of wear.MethodologyNinety bovine crowns were prepared and samples were randomly distributed into 6 groups (n=15): 0.1% citric acid solution (pH 2.5); Coca-Cola ® Soft Drink (pH 2.6); Fini ® Diet (lactic and citric acid, pH 3.3); Fini ® Jelly Kisses (lactic and citric acid, pH 3.5); Fini ® Fruit Salad Bubblegum (maleic acid, pH 2.6); Fini ® Regaliz Acid Tubes (maleic and citric acid, pH 3.1). Sweets were dissolved in the proportion of 40 g/250 mL of deionized water. Enamel samples were submitted to erosive challenges for 7 days (4 daily acid immersion cycles for 90 s each). Enamel wear was measured using contact profilometry (μm), and data (median values [interquartile range]) were submitted to Kruskal-Wallis/Dunn’s test (p<0.0001).ResultsAll citrus sweets tested present a high erosive potential, Fini Diet ® (2.4 [1.2]) and Fini Regaliz Tubs ® (2.2 [0.5]) show the highest erosive potential, similar to 0.1% citric acid (2.3 [0.7]); Fini Regaliz Tubs ® is more erosive than Coca-Cola ® (1.4 [0.9]).ConclusionThe evaluated citrus sweets have great erosive potential and play a key role in the development of ETW.

Effect of bioactive glasses and neodymium:yttrium-aluminum-garnet laser on dentin permeability.

Context:Dental hypersensitivity and loss of dental tissues are commonly observed in patients, and most of the problems are caused due to total or partial exposure of dentinal tubules.Aims:The purpose of this study is to evaluate the performance of 45S5 bioactive glass and niobophosphate (NbG) associated with neodymium: yttrium-aluminum-garnet (Nd:YAG) laser for the reduction of dentin permeability.Materials and Methods:Fifty bovine dentin discs were made and distributed randomly into five groups (n = 10). The Nd:YAG laser was applied with the bioactive glasses using the energy parameters (60 and 80 mJ), forming the groups; NbG_60: NbG + Nd:YAG (60 mJ); NbG_80: NbG + Nd:YAG (80 mJ), 45S5_60: 45S5 + Nd:YAG (60 mJ); 45S5_80: 45S5 + Nd:YAG (80 mJ) and C: control (untreated dentin). The permeability was measured with a split chamber device. The samples were subjected to the erosive challenge and a new permeability measurement was done. Furthermore, the dentin was analyzed by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS).Statistical Analysis Used:The data were analyzed using Kruskal–Wallis and Dunn's tests (α = 0.05).Results:Greater reduction in dentinal permeability was observed for 45S5 bioactive glasses (45S5_60 and 45S5_80) followed by NbG_80 and NbG_60 (P < 0.05). The SEM/EDS analysis showed the formation of a barrier after the dentin treatment.Conclusions:Bioactive glasses with Nd:YAG laser on the dentin surface may be a promising alternative for the reduction of dentin permeability.

Comparative Effect of Calcium Mesoporous Silica Versus Calcium and/or Fluoride Products on the Reduction of Erosive Tooth Wear and Abrasive Enamel Lesion

Objective: To evaluate the effect of a calcium nanocompound on the reduction of erosive tooth wear and abrasion. Material and Methods: Bovine enamel specimens (BE), were randomly assigned to the following groups (n = 10): G1 = Calcium mesoporous silica nanoparticles (Ca 2+ MSNs); G2 = casein phosphopeptide-amorphous calcium phosphate (CPP-ACP, 2% CPP-ACP, GC ® ); G3 = casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP, 2% CPP-ACP + 900 ppm F - , GC ® ); G4 = sodium fluoride NaF (900 ppm F-, positive control); and G5 = distilled and deionized water (negative control). Each product was applied to the exposed area for one minute, three times per day for three consecutive days, and followed by the immersion of the specimens in Sprite Zero™ - a low-pH solution (2.58) for five minutes (Coca-Cola™). After the first and last erosive challenges of the day, the specimens were submitted to abrasion in a toothbrush machine for 15 seconds (200 g/BE). The specimens were analysed using 3D non-contact optical profilometry, with tooth structure loss (TSL) measurements and scanning electron microscopy (SEM). TSL values were analysed by Kruskal-Wallis and Mann-Whitney tests (p<0.05) . Results: There were no significant differences between G1 (10.95 µm) and G3 (10.80 µm) treatments for TSL values; however both resulted in significantly reduced TSL values compared with the G5 (16.00 µm) (p<0.05). The G4 (12.26 µm) showed no statistically significant difference when compared to the G5 (16.00 µm). The groups G1 and G3 presented higher surface preservation than the G5 . Conclusion: Ca 2+ MSNs was effective for reducing tooth surface loss caused by erosive tooth wear and abrasion.

Effect of silver diamine fluoride on the prevention of erosive tooth wear in vitro

ObjectivesTo investigate the ability of silver diamine fluoride (SDF) to prevent erosive tooth wear in enamel and dentin. MethodsSDF (38 %) was compared to deionized water (DIW, negative control), potassium fluoride (KF, fluoride control), silver nitrate (AgNO3, silver control), and fluoride varnish (FV, clinical reference) using erosion and erosion-abrasion cycling models. Bovine enamel and dentin slabs were embedded in resin blocks. Two resin blocks were glued to form study blocks (n=8, per treatment), one for erosion and the other for the erosion-abrasion model. The blocks were treated once and then subjected to a five-day cycling model, with five daily citric acid erosive challenges (0.3 % citric acid/pH 2.6). Abrasion was performed using a toothbrushing machine with a medium-abrasive silica as abrasive (erosion-abrasion model only). Artificial saliva was used to remineralize the specimens after erosion/abrasion and as storage media between cycles. Surface loss (SL) was determined by non-contact profilometry. Data were analyzed using ANOVA (α=0.05). ResultsBoth eroded-abraded enamel and dentin specimens exhibited significantly more SL in all treatment groups than the only eroded ones (p<0.001). For dentin, both AgNO3 and DIW groups had significantly more SL than SDF, KF, and FV groups (p<0.001), for both models. For enamel, specimens had more SL in both AgNO3 and DIW groups compared to SDF, KF, and FV groups, in the erosion model. When enamel specimens were subjected to erosion-abrasion, FV resulted in the least SL (p<0.001). ConclusionSDF was effective in reducing dental erosion on both substrates, but dental erosion-abrasion only on dentin. Clinical significanceSDF may become a viable intervention for ETW prevention in dentin (e.g. exposed roots) once its efficacy has been confirmed under clinical conditions.

Effect of in situ aspartame mouthwash to prevent intrinsic and extrinsic erosive tooth wear.

BackgroundThe aim was to evaluate whether aspartame regular mouthwash prior to erosive challenges with citric or hydrochloric acids would be able to prevent erosive enamel wear. Material and MethodsThis randomized, single blind in situ study was conducted with 3 crossover phases of 5 days. Polished bovine enamel blocks (n=252) were randomly divided among 6 groups/ 3 phases/ 21 volunteers. The groups under study were: aspartame solution (0.024% of aspartame in deionized water - experimental group), deionized water (negative-control) and stannous-containing solution (Elmex® Erosion Protection Dental Rinse; positive-control); subjected to erosion on citric acid or hydrochloric acid. Four times per day the volunteers rinsed the intraoral appliance with the respective solutions (in situ) prior to immersion of half of the appliance in 0.05M citric acid and the other half in 0.01M hydrochloric acid for 120 seconds (extraoral). The response variable was enamel loss by profilometry. Data were analyzed by ANOVA and Tukey’s test (p<0.05). ResultsNo difference on enamel loss was found between aspartame solution and deionized water. Stannous-solution resulted in less enamel loss compared to deionized water. Hydrochloric acid resulted in higher enamel loss than citric acid. ConclusionsIn this model, aspartame was not able to prevent erosive tooth wear against citric or hydrochloric acids. Key words:Dental erosion, aspartame, stannous fluoride, citric acid, hydrochloric acid.

In vitro dentine tubule occlusion by a novel toothpaste containing calcium silicate and sodium phosphate

ObjectivesTo investigate the deposition, formation of hydroxyapatite (HAP) and acid resistance of dentine surfaces following brushing with a toothpaste containing calcium silicate and sodium phosphate (CSSP) and fluoride in vitro. MethodsHuman dentine specimens were brushed with a slurry of CSSP toothpaste followed by exposure to simulated oral fluid (SOF) in two in vitro studies, with a silica-based non-occluding toothpaste as control. The surface and tubule deposits were analysed after 14 cycles with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In a third study, dentine specimens were additionally exposed to citric acid erosive challenges for 30, 300 or 600 s after 2, 6, 10 and 14 cycles of SOF and either the CSSP toothpaste or a positive control toothpaste containing calcium sodium phosphosilicate and fluoride. The level of tubule occlusion was evaluated using SEM. ResultsThe SEM analyses indicated complete coverage of the dentine surface following 14 cycles of brushing with CSSP toothpaste with no observable patent tubules, in contrast to the non-occluding control toothpaste. The TEM and SAED analyses confirmed the deposited material on the surface and within tubules was HAP. The deposited material from CSSP toothpaste was more acid resistant than the deposited material from the positive control toothpaste at all time points and acid exposure levels (p < 0.05). ConclusionsThe CSSP toothpaste fully occluded dentine tubules and formed the mineral HAP. The dentine deposition on and within dentine tubules was resilient to acid erosive challenges. Clinical significanceA novel toothpaste containing CSSP can form HAP on dentine surfaces and within tubules. The potential of this technology is for a novel approach for the protection of dentine surfaces to acid challenges and the reduction of dentine hypersensitivity.

Effect of Tooth Mousse on Enamel Erosion - An in vitro Study

In industrialized countries, dental erosion has gained much more attention due to decrease in dental caries. Remineralization of carious lesion can be enhanced by using casein phosphopeptide amorphous calcium phosphate (ACP) which is an effective remineralizing agent. Aim: The study is performed to assess the after effect of Tooth Mousse (CPP-Casein Phosphopeptide-ACP) paste on dental erosion produced by drinks by applying contact profilometer. Materials and Methods: Twenty human teeth (molar and premolar) were collected from patients with either compromised periodontal conditions or extracted due to orthodontic purpose. Samples were categorized into four groups, i.e., Group-I-Coca Cola (10), Group-II-Frooti (10), Group-III-Coca-Cola + Tooth Mousse (10), and Group-IV-Frooti + Tooth Mousse (10). Ph is calibrated by using pH meter with digital electrode. At baseline and after erosive exposure, surface roughness of samples was calculated using profilometer. The values were then statistically interpreted using Bonferroni Post-hoc test. Results: In the present study, after remineralization by Tooth Mousse (Group III and Group IV) change in surface roughness (Ra values) after erosive challenge and remineralization by Tooth Mousse were significant for Group III (Coke + Tooth Mousse) when compared with Group-I (Coke), whereas it was nonsignificant for Group – IV (Frooti + Tooth Mousse) when compared to other Group-II. Conclusion: The present study shows protective effect of CCP-ACP paste on dental erosion that is caused by drinks.

Morphological and chemical effects of in-office and at-home desensitising agents containing sodium fluoride on eroded root dentin

ObjectiveThe aim of this study was to evaluate the morphological and chemical effect of in-office and at-home desensitising agents containing sodium fluoride (NaF) on eroded root dentine in vitro. MethodsFifty bovine dentine samples were pre-eroded and randomised into five groups (n = 10): G1 (Control) - milli-Q water; G2 - fluoride varnish containing NaF 22,500 ppm; G3 - desensitising cream containing NaF 9,000 ppm associated with 20% nanohydroxyapatite; G4 - toothpaste with NaF 5,000 ppm associated to tricalcium phosphate; G5 - toothpaste containing NaF 900 ppm and casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF). The specimens were submitted to erosive challenge for three days. The analyses were performed using non-contact profilometry for volumetric (Sa) and linear roughness (Ra) followed by scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The data were analysed by Kruskal-Wallis and Wilcoxon tests (α = 0.05). ResultsThere was a significant reduction of Ra and Sa for the eroded samples from the G2 and G5 (p < 0.05) after an erosive challenge. The dentine surface topography pattern showed partially or totally occluded dentinal tubules after treatments, except in the control group. The control, G4 and G3 groups showed a reduction in the dentine inorganic content percentage of Ca (Calcium) and P (Phosphorus) minerals. ConclusionThe fluoride varnish and CPP-ACPF toothpaste were able to prevent morphological changes and were the only materials that showed the Ca and P content increased after treatment. These materials may be promising alternatives in the clinical control of dentin erosion.

Cup-shaped tooth wear defects: more than erosive challenges?

The underlying mechanism of the development of cups and grooves on occlusal tooth surfaces is still unclear. The aim of this study was to evaluate factors contributing to in-vitro cup formation, and to elucidate the clinical process. Extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in combination with different loading conditions: no load (0N, control), 30N or 50N. Before and after 3 months exposure, the samples were scanned using a non-contact profilometer. A statistically significant difference between a loading of 0N and 50N was found at pH 4.8 (p < 0.002). Cup shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups. The study showed that a cup can arise fully in enamel and that this requires simultaneous acidic and mechanical loading.

“We will change whether we want it or not”: Soil erosion in Maasai land as a social dilemma and a challenge to community resilience

Soil erosion is a major environmental challenge that undermines economic development in many regions of the world. While much previous work explored physical processes behind this problem, less attention has been paid to social, cultural, and psychological parameters that make a significant impact on soil erosion through the land use practices that they support. The present paper addresses this gap by conducting a qualitative exploration of agro-pastoralist stakeholders' experiences of soil erosion in northern Tanzania, using the community resilience framework and the social dilemmas approach as theoretical lenses. Interview data suggests that the factors that make communities vulnerable to soil erosion challenges include the centrality of cattle keeping practice to pastoralists’ cultural identity, lack of social cohesion, lack of alternative livelihood opportunities, and weak governance structures. We argue that the ways towards resolving the dilemma lie in addressing relevant cultural norms, building cohesive and open communities, and strengthening local governance.

Can surface protection prevent damage in margins of composite resin restorations after simulated endogenous erosion?

Aim: The study investigated the effect of using surface protection agents in the adaptation of external and internal margins of restorations subjected to simulated erosion. Methods: Cavities with margins in dentin were prepared in bovine incisors (n=120). Adhesive restorations were placed using a three-step etch&amp;rinse adhesive system and nanofilled composite resin. The specimens were divided into four groups, according to the surface protection: negative control, topical application of fluoride (TAF), resin sealant and resin-modified glass ionomer varnish (RMGI varnish). Afterwards, they were divided into three sub-groups, according to the exposure to a simulated solution of gastric acid (DES) (5% HCl, pH=2,2) and subsequent remineralization (RE): negative control, 9 and 18 cycles of DES-RE. The evaluation of the tooth-restoration interface was performed on the internal and frontal images with the aid of a stereoscopic microscope (15x), and the percentage of continuous margins without adhesive failures was quantified. Results: In the external margins, only those groups with surface protection using sealants (resin and glass-ionomer) did not exhibit a significant decrease in the percentage of continuous margins after the erosive challenges. After 18 cycles of DES-RE, the use of resin-modified glass ionomer varnish resulted in the highest percentage of continuous margins. Conclusion: It was concluded that physically covering the surfaces with a sealing agent preserved the marginal adaptation of composite resin restorations exposed to endogenous erosive challenges.

Sediment transport capacity in erodible beds with reconstituted soils of different textures

Precise estimation of sediment transport capacity and wide applicability of a prediction equation could provide a positive response to increasing challenges of soil erosion. Currently, the models developed by many researchers are focused on a few or single soils. In this study, a prediction equation of sediment transport capacity was attempted to establish from the flume experiments performed on erodible beds under the experimental settings of two slopes (5.6%, 16.7%), four unit width discharges (6.67 × 10−5, 1.33 × 10−4, 2.00 × 10−4 and 2.67 × 10−4 m2 s−1) and five reconstituted soils (sand contents of 0%, 30%, 50%, 70%, 100%). Here, the sediment transport capacity under clay-sand mixture of different soil texture were analyzed, and a prediction equation for sediment transport based on soil cohesion and hydraulic variables was established. The experiments confirmed that the sediment concentration and transport capacity increased with the unit width discharge and slope gradient as a power function, and was more dependent on slope gradient. Besides, the hydrological and erosive processes on the beds with reconstituted soils varied with soil texture, the beds with a high clay content had a stable channel of sediment transport. Comparatively, unit stream power was the most suitable hydraulic variable to describe the sediment transport capacity (r = 0.951, P < 0.01). The introduction of soil cohesion of bed materials further improved the reliability of the prediction equation by combining the soil cohesion and unit stream power as a composite predictor (R2 = 0.940, NSE = 0.943, P < 0.01). The new equation could provide dependable prediction for various erodible beds with packed soils of different textures. Soil cohesion could be considered as an indicator of soil properties in prediction equation of sediment transport capacity. Given the broad range of physical properties of reconstituted soils of different textures, the results are applicable to a wide variety of soil types.

Climate Change, Sea Level Rise, and the Slow Erosion of “Home”

Abstract This photo essay explores the growing challenges of coastal erosion and sea level rise through a personal reflection about coastal California. The author combines photography, ethnographic research, and personal experience to reflect upon the social, political, and environmental changes that rising seas are bringing to the world's coastlines. The essay emphasizes the power of using anthropology, framed by locally-based perspectives and knowledge, as a way to understand the broader global issues of climate change, erosion, and sea level rise.

Antierosive Effect of Topical Fluorides: A Systematic Review and Meta-Analysis of In Situ Studies.

BACKGROUND:The effectiveness of the application of topical fluorides in prevention of erosive tooth wear has been an issue of controversy in the literature. The objective of this systematic review was to assess in situ studies investigating the effects of using topical fluorides on prevention of erosive tooth wearMATERIAL AND METHODS:Two electronic databases PubMed/MEDLINE and Cochrane Central Register of Controlled Trials were searched. Eligibility criteria included in situ-controlled studies that assessed the effect of the erosive process without additional tooth brushing. The search involved English-written articles only. A total of 684 potentially relevant titles and abstracts were found after removal of duplicates, of which 22 full-text articles were selected. Seventeen studies were included in the qualitative synthesis of which 6 studies included in the meta-analysis. The following data were obtained for each study: authors, year of publication, country, study design, periods of study, duration, blinding, interventions (type/concentration/form), tooth substrate, location of the intraoral appliance, number of samples attached to each appliance, type of acidic media used for erosive challenge, duration of erosive challenge, subjects (number/age/sex), reported side effects -if any-, measuring device, amounts of tissue loss.RESULTS:The risk of bias of the included studies was assessed using the Cochrane Collaboration tool for assessing the risk of bias. A meta-analysis of the present study was performed using Comprehensive Meta-Analysis version 2.2.048 software.CONCLUSION:The use of oral hygiene products containing AmF/NaF/SnCl2 or NaF may be effective in the prevention of erosive tooth wear.

Resistência da união de restaurações confeccionadas com sistemas adesivos universais em dentes acometidos por erosão ácida

Objetivos: Avaliar a resistência adesiva de diferentes sistemas adesivos universais em esmalte e dentina erodidos. Métodos: As unidades experimentais foram compostas por 30 fragmentos de esmalte bovino e 30 fragmentos de dentina bovina divididos aleatoriamente em três grupos experimentais de acordo com os sistemas adesivos universais utilizados (n = 10): Single Bond Universal (3M ESPE), Peak Universal (Ultradent) e Ambar Universal (FGM). Previamente as restaurações, os fragmentos de esmalte e dentina foram submetidos à desafio erosivo em ácido cítrico a 0,3% (pH = 2,6) durante cinco minutos, quatro vezes por dia por cinco dias. Um cilindro de resina composta (Forma, Ultradent) com 2mm de diâmetro foi construído em cima de cada fragmento. A resistência ao cisalhamento foi avaliada em máquina de ensaio universal (1mm/min). Os valores obtidos de resistência da união (MPa) foram analisados por ANOVA dois fatores e teste de Bonferroni (α=0,05). Resultados: Não houve diferença significativa entre os sistemas adesivos testados no mesmo substrato. O esmalte apresentou maiores valores de resistência da união que a dentina. Houve predomínio da falha coesiva em resina no esmalte e falha adesiva na dentina. Conclusão: Os sistemas adesivos universais testados apresentaram resistência adesiva semelhantes entre si dentro do mesmo substrato erodido.

Randomised study of the effects of fluoride and time on in situ remineralisation of acid-softened enamel

ObjectivesThis single-centre, randomised, crossover study used a short-term in situ dental erosion remineralisation model to explore the remineralisation of acid-softened enamel in the 4-h period immediately following brushing with an anti-erosion, dentin hypersensitivity test dentifrice containing 1150 ppm fluoride (as sodium fluoride [NaF]) or a placebo dentifrice with no fluoride.Materials and methodsFifty participants wearing a palatal appliance holding surface-softened bovine enamel specimens brushed their natural teeth with their assigned dentifrice. Specimens were removed at 5-, 10-, 15-, 30-, 60-, 120- and 240-min post brushing. Enamel remineralisation effect was evaluated at each timepoint by percent surface microhardness recovery (%SMHR) and enamel fluoride uptake (EFU). After a second in vitro erosive challenge, the percent relative erosion resistance (%RER) was calculated.ResultsStatistically significant differences in %SMHR were observed for the test dentifrice compared with the placebo dentifrice from the 60-min timepoint onwards (all p < 0.02; mean difference of 8.66 [95% CI 3.46, 13.87] at 60 min). At each specimen removal time, %RER and EFU were statistically significantly higher for the test dentifrice compared with the placebo dentifrice (p < 0.0001 for all). No treatment-related or serious adverse events were reported.ConclusionsThe NaF-containing anti-erosion, dentin hypersensitivity dentifrice improved remineralisation of acid-softened enamel starting at 60 min of intra-oral exposure. It also improved enamel erosion resistance and fluoride uptake as early as 5 min after exposure to fluoridated dentifrice slurry.Clinical relevanceBrushing with a NaF-containing dentifrice can rapidly improve remineralisation, enamel erosion resistance and fluoride uptake.

The effect of two different toothpastes and tooth brushing timing on enamel surface microhardness after an erosive challenge – Ex vivo study

Introduction: Excessive consumption of carbonated beverages, fruit juices, high-energy drinks, and candies are the main causes of erosive dental lesions. Several studies have shown that phosphoric, citric acids and other substances present on these products have an erosive action on enamel surface [1]. The aim of this study is to compare the effect of two different toothpastes, with fluoride or chlorhexidine, and toothbrush timing on enamel surface microhardness after an erosive challenge with Redbull®. Materials and methods: Sample was obtained from 10 human molars (intact, caries/fracture-free). This study was approved by Egas Moniz Ethics Committee. Each tooth was sectioned in four enamel specimens (4x3mm) giving rise to 40 enamel specimens, randomly assigned in 4 different groups (n = 10): Group A - specimens were subjected to an erosive challenge (EC) with Redbull® 3 minutes, 4 times a day, 5 days and brushed with a fluoride based toothpaste immediately after (Oral B® pro-expert); Group B - EC, and brushed with a chlorhexidine based toothpaste immediately after (CHX - Elgydium® gum protection); Group C – EC, specimens were submersed two hours in artificial saliva, at 37ºC, and then tooth brushed with the same fluoride based toothpaste of group A; Group D – EC specimens were submersed two hours in artificial saliva, at 37ºC and then tooth brushed with the same chlorhexidine based toothpaste of group B. Enamel surface microhardness values were obtained with a Vickers Microhardness tester. One-way ANOVA was used for the comparison of group microhardness means and post hoc tests (Bonferroni test) for pairwise comparison of groups. Statistical significance was accepted at p < 0.05. Results: Enamel surface microhardness mean values were: Group A – 275.36 ± 50.10 HV; Group B – 304.60 ± 36.15 HV; Group C – 361.78 ± 36.17 HV; Group D – 387.16 ± 39.01 HV. Statistical analysis of data has shown no significant differences between the means of groups A and B (p = 0.117), and between the means of groups C and D (p = 0.172). However, there is statistical evidence that means of groups A and B are significantly different than means of groups C and D (p < 0.001). Discussion and conclusions: Our results suggest the best timing for tooth brushing after the extrinsic erosion of enamel with a high-energy drink should be two hours, rather than immediately after the erosive challenge. No significant differences were found in enamel surface microhardness mean values when brushing with the fluoride based compared with the chlorhexidine-based toothpaste, considering the same brushing time.