Erosive Challenge Research Articles

The effect of different desensitizing strategies on eroded dentin: ex vivo study

Introduction: Conditions like gastroesophageal reflux disease, eating disorders, chronic alcoholism and others promote the contact of gastric acid (HCl) with the oral cavity, resulting in dental erosive lesions [1]. Study hypothesis: there are no differences on the microscopic aspect of eroded superficial and deep dentin after using two different desensitizing toothpastes. The aim of this study is to evaluate microscopic characteristics of eroded superficial and deep dentin when exposed to desensitizing toothpastes. Materials and methods: Sample was obtained from 2 human molars (intact, caries/fracture-free). Each tooth was sectioned in eight parts (4-superficial dentin and 4-deep dentin), giving rise to 16 dentin specimens, randomly assigned in 4 different groups which were divided into 2 subgroups (superficial (s), n = 2 and deep (d), n = 2): Group As and Ad – sound dentin; Group Bs and Bd – Intrinsic erosive challenge (ec) with HCl at pH 2,6 for 60s; Group Cs and Cd – ec and toothbrush, two minutes, twice a day, seven days with stannous fluoride toothpaste; Group Ds and Dd – ec and toothbrush, two minutes, twice a day, seven days with strontium chloride toothpaste. Dentin surface was analyzed with scanning electron microscopy, with magnifications of 1000×, 5000× and 10000×. The study was approved by the Ethics Committee for Health, of Egas Moniz (Reference Number: 523). Results: On superficial dentin: partial and heterogeneous occlusion of the tubules was observed in group Ds; in group Cs there was no tubule occlusion. On deep dentin samples, partial tubule occlusion was observed in groups Cd and Dd, higher on group Dd. Discussion and conclusions: Qualitative analysis of scanning electron microscopy images suggests that Strontium Chloride based toothpastes are capable of promoting a greater dentinal tubule occlusion. The use of Stannous Fluoride toothpaste showed less favorable results, with tubule occlusion occurring only on deep dentin. Figure 1.

Cup-Shaped Tooth Wear Defects: More than Erosive Challenges?

Background/Aim: 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, in order to elucidate the clinical process. Methods: A total of 48 extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in constant motion, in combination with different loading conditions: no load (0N group, control), 30 N (30N group) or 50 N (50N group) (n = 8 per group). Before and after 3 months of exposure (1,422,000 loading cycles), the samples were scanned using a non-contact profilometer. Pre- and post-exposure scans were subtracted and height loss and volume tissue loss were calculated. Representative samples with wear and cupping lesions were imaged using scanning electron microscopy, light microscopy and micro-computed tomography. Results: Average height and volume tissue loss at pH 5.5 was 54 µm and 3.4 mm³ (0N), 52 µm and 3.4 mm³ (30N) and 58 µm and 3.7 mm³ (50N), respectively, with no statistically significant differences. Average height and volume loss at pH 4.8 were 135 µm and 8.7 mm³ (0N), 172 µm and 12.6 mm³ (30N) and 266 µm and 17.8 mm³ (50N), respectively, with a statistically significant difference between 0N and 50N (p < 0.002). Cup-shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups. Conclusion: The study showed that a cup can arise fully in enamel and that mechanical loading in addition to erosive challenges are required.

Water sorption and solubility of a nanofilled composite resin protected against erosive challenges

Objective: Erosive challenges are capable of demineralizing dentin and promote physical and mechanical changes in restorative materials. The present study investigates the water sorption and solubility of one nanofilled resin composite submitted to erosive challenges. It also studies procedures that can protect these surfaces. Materials and methods: 120 specimens were used. It was divided into four experimental groups according to the type of surface protection used (negative control, topical application of fluoride, resin-modified glass ionomer varnish and resin-based sealant). Subsequently, they were randomly assigned to three subgroups (n = 10), (negative control, 9 and 18 cycles of DES-RE). According to the exposure to the simulated solution of gastric acid (DES) (5% HCl, pH = 2.2) and subsequent remineralization (RE). The specimens were dehydrated until a constant mass was obtained and immersed in distilled water for 7 days, when they were weighed and submitted to a new dehydration. The values of water sorption and solubility were calculated according to the ISO 4049: 2000 specifications and analyzed statistically (2-way ANOVA / Tukey, alpha = 5%). Results: The water sorption and solubility averages after 18 cycles of DES-RE were statistically higher than negative control. Independently of the erosive challenge received, the specimens protected with the resin-modified glass ionomer varnish presented a significant increase in the values of loss and mass gain in relation to the other groups. Conclusion: No control method presented promising surface protection capacity of composite resin against to erosive challenges.KeywordTooth erosion; Dental restoration permanent; Solubility.

Resin-Based Materials Protect Against Erosion/Abrasion-a Prolonged In Situ Study.

While patient compliance is key to preventive measures related to dental erosion, the application of resin-based materials could serve as an additional treatment to inhibit erosion progression. This in situ study evaluated the effect of applying resin-based materials, including resin infiltrant, on previously eroded enamel subjected to prolonged erosive and abrasive challenges. The factors under study were types of treatment (infiltrant [Icon], sealant [Helioseal Clear], adhesive [Adper Scotchbond Multi-Purpose Plus], and control [no treatment]); wear conditions (erosion [ERO] and erosion + abrasion [ERO + ABR]) and challenge time (5 and 20 days) in a single-phase study. The blocks were prepared from bovine enamel, eroded (0.01 M HCl, pH 2.3 for 30 seconds) and randomized among treatments, wear conditions, and volunteers. The application of resin-based materials followed the manufacturers' recommendations. Twenty-one volunteers wore the palatal intraoral device, in which one row corresponded to ERO and the other to ERO + ABR. In each row, all treatments were represented (2 blocks per treatment). For 20 days, the erosive challenge was performed 4 times/day (immersion in 0.01 M HCl, pH 2.3, for 2 minutes) for the ERO condition. For the ERO + ABR condition, two of the erosive challenges were followed by abrasion for 15 seconds with fluoride dentifrice slurry. Enamel and/or material loss was measured using profilometry (initial, after treatment, and after the end of the fifth and 20th days of in situ erosive challenge) and analyzed by ANOVA models and Tukey's test (α=0.05). The results showed that the application of resin-based materials did not cause superficial enamel loss. The infiltrant group showed a thicker layer of material above the enamel compared with the other materials (p=0.001). After the erosive challenge, there was no difference between the conditions ERO and ERO + ABR (p=0.869). All materials protected the enamel against erosion progression compared with the control group (p=0.001). Based on these results, we conclude that the application of resin-based materials results in protection of previously eroded enamel subjected to in situ erosive and abrasive challenge for 20 days.

Effect of CPP-ACPF and Nano-hydroxyapatite Preventive Treatments on the Susceptibility of Enamel to Erosive Challenge.

The purpose of this in vitro study was to evaluate the effect of two preventive clinical treatments on bovine enamel susceptibility after erosive challenge induced by a soft drink. Eighteen sound bovine incisors were used for this study. Three experimental groups were assigned as follows: Group 1 was the control group; Group 2 specimens received a CPP-ACPF paste treatment; and Group 3 specimens received a treatment with a product containing 1% nano-hydroxyapatite and 455 ppmF-. The specimens were submitted to erosive challenge using a common soft drink (Coca Cola). The erosive activity on the enamel was evaluated by measuring surface microhardness change (Vickers method), surface roughness alterations and surface loss (vertical scanning interferometry (VSI) method). The data were statistically analysed using one-way analysis of variance (ANOVA) and Tukey's post-hoc test at a level of statistical significance a = 0.05. The tested treatments exhibited significantly lower decreases in surface microhardness compared to the control group after the erosive challenge (p < 0.05). The tested treatment groups did not show statistically significant lower increases in surface roughness compared to the control group (p > 0.05). In addition, the treatment groups exhibited statistically significant lower surface loss than the control group (p < 0.05). Although the tested treatments reduced erosive activity, none of them provided complete protection against the development of enamel erosion, which means that they should be only used as a part of an individually tailored preventive programme.

45S5 Bioglass paste is capable of protecting the enamel surrounding orthodontic brackets against erosive challenge.

OBJECTIVES:This study aimed at evaluating the effect of using a 45S5 bioglass paste and a topical fluoride as protective agents against acidic erosion (resembling acidic beverage softdrinks intake) for enamel surrounding orthodontic brackets.MATERIALS AND METHODS:Sample of 21 freshly extracted sound incisor and premolar teeth was randomly divided into three equal groups: a bioglass group (Bioglass) (NovaMin, 5-mm average particle, NovaMin Technology), a Fluoride group (Fluoride) (Gelato APF Gel, Keystone Industries), and a control group (Control). Orthodontic brackets were bonded to the utilized teeth usingMIP (Moisture Insensitive Primer) and Transbond PLUS color change adhesive. All specimens were challenged by 1% citric acid for 18 min. The top enamel surfaces next to the orthodontic brackets were examined by SEM-EDS. Wilcoxon Signed-Rank test was used to compare the area covered by the 45S5 bioglass paste before/after erosion P < 0.05.RESULTS:45S5 bioglass paste application resulted in the formation of an interaction layer that significantly resisted erosion challenge P < 0.05. The fluoride and control specimens showed signs of erosion of the enamel next to the orthodontic brackets (P < 0.05).CONCLUSION:45S5 bioglass paste can efficiently protect the enamel surfaces next to orthodontic brackets for acidic erosion challenges.

Influence of mandibular and palatal intraoral appliances on erosion in situ study outcome.

The standardization of in situ protocols for dental erosion is important to enable comparison between studies.Objective:Thus, the objectives of this study were to evaluate the influence of the location of in situ intraoral appliance (mandibular X palatal) on the extent of enamel loss induced by erosive challenges and to evaluate the comfort of the appliances.Material and Methods:One hundred and sixty bovine enamel blocks were selected according to their initial surface hardness and randomly divided into two groups: GI - palatal appliance and GII - mandibular appliance. Twenty volunteers wore simultaneously one palatal appliance (containing 4 enamel blocks) and two mandibular appliances (each one containing 2 enamel blocks). Four times per day during 5 days, the volunteers immersed their appliances in 0.01 M hydrochloric acid for 2 minutes, washed and reinserted them into the oral cavity for 2 hours until the next erosive challenge. After the end of the in situ phase, the volunteers answered a questionnaire regarding the comfort of the appliances. The loss of tissue in the enamel blocks was determined profilometrically. Data were statistically analyzed by paired t-test, Chi-square and Fisher's Exact Test (p<0.05).Results:The enamel blocks allocated in palatal appliances (GI) presented significantly higher erosive wear when compared to the blocks fixed in mandibular appliances (GII). The volunteers reported more comfort when using the palatal appliance.Conclusions:Therefore, the palatal appliance is more comfortable and resulted in higher enamel loss compared to the mandibular one.

Effect of Metalloproteinase Inhibitors on Bond Strength of a Self-etching Adhesive on Erosively Demineralized Dentin.

To analyze the influence of epigallocatechin-3-gallate (EGCG) and chlorhexidine (CHX) on adhesive-dentin bond strength of a self-etch adhesive to sound dentin (SD) and eroded dentin (ED). Thirty-six middle-dentin samples were assigned to six groups (n = 6) according to pretreatment (DW: distilled water, control; 0.1% EGCG; or 2% CHX) and erosive challenge (presence or absence). Specimens were subjected to 2-h acquired pellicle formation, then half of them were exposed to 1% citric acid three times a day for five days. SD and ED were treated with the tested solutions for 60 s, and then Clearfil SE Bond was applied before resin composite buildup. Bonded teeth were longitudinally sectioned into sticks and half were immediately tested, while the remaining specimens were tested after six months. The mode of fracture was examined and the microtensile bond strength (µTBS) measured. Statistical analysis was performed with ANOVA and Bonferroni tests. At both time periods, regardless of the dentin substrate, EGCG groups did not show bond strengths that were significantly different from those obtained with DW (p > 0.05), while CHX generated lower values than did DW (p < 0.05). On SD, there was a bond strength reduction only in the CHX groups after six months. However, for ED, the bond strength significantly decreased in all groups. CHX negatively affected both dentin substrates, while the pretreatment with EGCG did not affect µTBS over time on SD. µTBS may be influenced by the substrate over time and EGCG can be used as an alternative to CHX to maintain the bond strength of self-etching adhesives.

Properties of fusion-relevant liquid Li-Sn alloys: An ab initio molecular-dynamics study

Plasma-facing conditions in a fusion reactor present challenges of erosion and brittleness for solid materials; a liquid metal alternative potentially could provide a self-healing and replenishing first wall. Among the most promising candidates, Li-Sn alloys have desirable characteristics derived from both of their elemental constituents. However, their deployment has been limited due to a lack of experimental data for many properties at the concentration ratios of interest (Li30Sn70 and Li20Sn80). Here, we present ab initio molecular-dynamics studies of this alloy at both concentration ratios and evaluate relevant properties, including static structure factors and diffusion coefficients of bulk alloys, as well as density profiles and surface segregation of the liquid Li30Sn70 film.

Eroded enamel rehardening using two intraoral appliances designs in different times of salivary exposure.

BackgroundThe aim of this study was evaluated the eroded enamel rehardening potential using upper palatal and lower buccal removable appliances in different times of salivary exposure (30 min, 1h, 2h, 12h) after a single erosive challenge event.Material and MethodsAfter initial surface hardness evaluation, bovine enamel blocks were eroded in vitro (0.01 M hydrochloric acid, pH 2.3, 30 seconds), selected (n = 160) and randomly assigned to the two appliance designs and twenty volunteers. Four enamel blocks were inserted in each removable appliance. On the in situ phase, the volunteers were instructed to use the upper palatal and lower buccal appliances simultaneously for 12 nonconsecutive hours. After each predetermined period of time of salivary exposure, the enamel blocks were removed from the appliances for immediate evaluation of surface hardness, enabling percentage of surface hardness recovery calculation (%SHR). The data were analyzed using two-way ANOVA and Tukey’s test (α=5%).ResultsThe results showed no difference in the degree of enamel rehardening by the upper palatal or lower buccal appliances (p >0.0001). Regarding the time of use of the appliances, it was demonstrated that 30 minutes (upper = 21.12%, lower = 19.84%) and 1 hour (upper = 35.69%, lower = 30.50%) promoted lower hardness recovery than two hours (upper = 44.65%, lower 40.80%) of salivary exposure (p<0.0001). The use of 12 hours (upper = 49.33%, lower = 49.00%), including the sleeping time of the volunteers did not increase the %SHR.ConclusionsThe location of the appliance does not influence the re-hardening ability of saliva and the use of intraoral appliances for 2 hours seems to be appropriate for partial rehardening of the softened enamel surface. Key words:Tooth erosion, in situ, saliva, tooth remineralization.

Effect of different methods of vital tooth bleaching on the resistance of enamel to erosion using Energy–Dispersive X-Ray Spectrometry analysis

Objectives: the objective of the current study was to determine the effect of different methods of vital tooth bleaching (power in- office, at-home and over the counter) on the resistance of enamel to erosion. Material and methods: Square enamel sections (4 mm × 4 mm × 3 mm) were obtained from the middle third of the crown of bovine teeth and then embedded in self-curing acrylic resin blocks measuring (2 cm wide and 3 cm high). The samples were divided randomly into 4 groups according to the method of bleaching used. Group 1(control group): where all specimens of the group were placed in artificial saliva at 370 C during the study period. Group 2 (power in- office bleaching): The gel was applied directly on the enamel surface of the specimens where the thickness of the gel was about 1-2 mm, then the LED bleaching device was used. The lamp was located close to enamel surface, then it was turned on for 15 minutes for total application time 45 minutes. Group 3 (Crest 3D White Luxe Supreme FlexFit White strips (over the counter) : the strips were applied to the enamel surface for 30 min twice daily for 14 days according to manufacturer instructions. Group 4 (At-home bleaching): bleaching gel was applied to the enamel surface. Teeth were placed for 6 hours at 370C daily for 8 days. Then, all the samples were subjected to erosive challenge where the bleached samples and the samples of control group were immersed in 1% citric acid solution. Mineral analysis via EDS was carried out before bleaching (base line), then of bleached enamel and finally after erosive cycle. Two representative samples of each group after each step were examined by scanning electron microscope. Results: There was a significant difference regarding the percentage weight of (Ca%), (P%) and (Ca/P%) among the four tested groups. The difference was not significant between group 1 and group 4 after erosion. Conclusions: 1-At-home beaching is considered the least harmful to enamel compared to power in- office and over the counter bleaching materials, and it is more resistant to erosive challenges. 2- Bleaching agents containing calcium decrease the adverse effects of the bleaching procedure. 3-Bleached enamel is less resistant to erosion especially when power in -office or over the counter protocol is used.

Impact of surface micromorphology and demineralization severity on enamel loss measurements by cross-polarization optical coherence tomography

ObjectivesOptical Coherence tomography (OCT) is a promising clinical imaging technology for quantitative and objective assessment of dental erosion. We aimed to determine the influence of enamel surface roughness and demineralization severity (by erosive challenge) on dental surface loss measurements by cross-polarization OCT (CP-OCT). Materials and methodsHuman enamel specimens were prepared with three surface roughness levels (very rough, rough and polished; n = 10 each). They were evaluated using CP-OCT and optical profilometry (gold standard) at baseline, and after 1, 2, 4, 6, 8, 16 and 24 h of erosion demineralization. The effects of roughness and demineralization on enamel loss were analyzed using ANOVA (alpha = 0.05). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to evaluate inter-method agreement and intra-examiner repeatability. ResultsCP-OCT surface loss measurements did not significantly differ with the changes in enamel surface roughness (p = 0.27). Among demineralization severities, CP-OCT surface loss measurements at 1, 2, 4 and 8 h did not differ among each other, but they showed significantly lower enamel loss than 16 and 24 h; 6 and 16 h were significantly lower than 24 h (p < 0.05). Overall, CP-OCT and optical profilometry measurements did not differ (p = 0.73); however, ICC was relatively low (ICC = 0.34). Enamel loss estimation by CP-OCT presented an error of approximately ± 150 μm compared to profilometry. Intra-examiner repeatability with CP-OCT was excellent (ICC = 0.98). ConclusionsEnamel roughness did not affect CP-OCT measurements. The estimated error of CP-OCT measurements limited the appropriate assessment of enamel erosion surface loss, in the magnitude simulated in this study. Clinical relevanceEnamel thickness measurement by CP-OCT presents potential as an objective method for monitoring dental erosion lesions; however, its use may be limited for the assessment of the initial stages of enamel surface loss by erosion.

Do fluoride toothpastes have similar preventive effect in permanent and primary teeth against erosive tooth wear?

Little is known about fluoride toothpastes effect on primary teeth submitted to erosive tooth wear. To evaluate the preventive effect of different toothpastes on surface loss (SL) after severe erosion/abrasion model and to compare this effect between permanent (PT) and primary teeth (pt). Enamel samples were randomly divided according toothpastes groups (n=17). G1: placebo; G2: NaF; G3: AmF-NaF-SnCl2 anti-erosion; G4: SnF2 ; and G5: NaF anti-erosion for children. Samples were incubated in artificial saliva (1hour), submitted to erosive challenge (3minutes; 1% citric acid; pH3.6; at 25°C) and to toothbrush abrasion (2minutes slurry immersion; 50 strokes; 200g) during 30 cycles. Surface loss (μm; mean±SD) was quantified by contactless profilometry. The effects of the two covariables "tooth" and "toothpaste" were analysed by non-parametric ANOVA, variables with significant effects were tested by Wilcoxon tests. pt showed significantly higher surface loss than PT in all groups (P<0.001). The mean values of SL of each group were: G1 PT 18.18(±3.98), pt 25.65(±9.21); G2 PT 14.76(±2.82), pt 18.11(±3.92); G3 PT 12.62(±5.29), pt 15.61(±6.70); G4 PT 17.12(±2.24), pt 23.41(±7.9); G5 PT 13.24(±1.29), pt 18.28(±8.96). In permanent teeth, G3 showed the best preventive effect. In primary teeth, G1, G3, and G5 showed similar effect.

Soil erosion in East Africa: an interdisciplinary approach to realising pastoral land management change

Implementation of socially acceptable and environmentally desirable solutions to soil erosion challenges is often limited by (1) fundamental gaps between the evidence bases of different disciplines and (2) an implementation gap between science-based recommendations, policy makers and practitioners. We present an integrated, interdisciplinary approach to support co-design of land management policy tailored to the needs of specific communities and places in degraded pastoral land in the East African Rift System. In a northern Tanzanian case study site, hydrological and sedimentary evidence shows that, over the past two decades, severe drought and increased livestock have reduced grass cover, leading to surface crusting, loss of soil aggregate stability, and lower infiltration capacity. Infiltration excess overland flow has driven (a) sheet wash erosion, (b) incision along convergence pathways and livestock tracks, and (c) gully development, leading to increased hydrological connectivity. Stakeholder interviews in associated sedenterising Maasai communities identified significant barriers to adoption of soil conservation measures, despite local awareness of problems. Barriers were rooted in specific pathways of vulnerability, such as a strong cattle-based cultural identity, weak governance structures, and a lack of resources and motivation for community action to protect shared land. At the same time, opportunities for overcoming such barriers exist, through openness to change and appetite for education and participatory decision-making. Guided by specialist knowledge from natural and social sciences, we used a participatory approach that enabled practitioners to start co-designing potential solutions, increasing their sense of efficacy and willingness to change practice. This approach, tested in East Africa, provides a valuable conceptual model around which other soil erosion challenges in the Global South might be addressed.

Influence of Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin

This in vitro study evaluated the influence of the Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin. Eighty dentin specimens were selected and divided into eight groups (n = 10): G1: negative control; G2: positive control (5% fluoride varnish-FV); G3: Er,Cr:YSGG laser; G4: FV+ laser; G5: 3% potassium oxalate; G6: 3% potassium oxalate + laser; G7: biphasic calcium silicate/phosphate gel (gel); G8: gel + laser. Laser parameters: 0.5W, 6.25J/cm2 at 1-mm distance. The erosive drink used was a cola soft-drink (pH = 2.42 at 4°C), lasting 5min, twice a day, with 6-h intervals between the challenges, during 14days. Kolmogorov-Smirnov and Levene's tests were satisfied. The surface roughness data were submitted to ANOVA and Tukey post hoc tests. For the wear profile, Kruskal-Wallis and Dunn post hoc tests were used. Afterwards, the Spearman correlation test was performed. All statistical tests assumed a significance level of 5% (α = 0.05). G1 presented the highest surface roughness value after the erosive challenge (3.586μm2 ± 0.205μm2) and the G7 presented the lowest surface roughness value after the erosive challenge (1.071μm2 ± 0.180μm2). For the lost volume, G4 presented the lowest percentage (9.7% ± 0.9%), while G1 had the highest percentage (41.8% ± 2.5%), both with p < 0.05. There was a weak correlation between the response variables (ρ = 0.33). All groups presented lower values of surface roughness and loss of volume when compared to the negative control group. For the surface roughness, the biphasic calcium silicate/phosphate gel presented the best result. For volume loss, the 5% fluoride varnish + Er,Cr:YSGG laser showed the best results compared to the other groups.

Diazepam as attenuator of pain induced by dentin hypersensitivity in rats exposed to stress

The pain in dentin hypersensitivity (DH) has distinct sensory and emotional origins, with variations that occur in different intensities for each individual. The aim of this study is to evaluate the effects of diazepam in the attenuation of the pain induced by DH. Design: Fifty male Wistar rats were divided into five groups: control group received water ad libitum (C); stress group received water ad libitum plus stress (S); DH induced by erosion challenge with isotonic solution ad libitum (G); DH and stress (GS); and DH, stress and diazepam (GSD) groups. Animals of the GS group were exposed to the New York Subway Stress Model. Animals treated with diazepam (GSD group) received 1 mg/kg every 3 days, from the 15th day of treatment until the end of the stress-inducing period. The body weights of rats were weekly registered. After 30 days, all groups were submitted to the DH test, which was assessed using cold water stimuli, and were graded 0, 0.5, 1, 2, or 3. Dental elements were evaluated using scanning electron microscopy (SEM). Results: 1) Groups G and GS presented the highest DH scores, which confirms that stress increased pain response; 2) GSD group had significantly reduced DH scores compared to G and GS groups; 3) SEM of dental elements showed exposed dentin tubules in G, GS, and GSD groups, as expected. Conclusions: diazepam attenuated pain induced by dentin hypersensitivity in rats exposed to stress.

The Challenge of Soil Erosion: Where Do We Now Stand?

The Challenge of Soil Erosion: Where Do We Now Stand?

Performance of a newly developed mineral gel system on erosive and erosive/abrasive enamel loss. An in vitro study

We compared the prevention of erosive and erosive/abrasive enamel loss by a medical minerals gel system (R.O.C.S.) to that by an anti-erosive toothpaste. Seventy-two bovine enamel samples were randomly allocated to six groups (E1–E3 and EA1–EA3; n=12). Per day, samples were eroded (2 min) 9 times using HCl (pH 2.6). Between erosive challenges and over night samples were stored in artificial saliva. Per day, samples were stored (100 s; groups E1–E3) or additionally brushed (20 brushing strokes; groups EA1–EA3) in/with slurries prepared from artificial saliva plus: no additional toothpaste (control groups E1 and EA1), elmex erosion protection toothpaste (groups E2 and EA2), or R.O.C.S. toothpaste (groups E3 and EA3). Once per day, samples of groups E3 and EA3 were additionally treated (40 min) with a slurry prepared from artificial saliva and R.O.C.S. medical minerals gel. After 7, 14 and 21 days enamel loss was measured by surface profilometry and analyzed by Kruskal-Wallis tests and Conover post-hoc tests. Under erosive conditions only (groups E1–E3), at each time point of measurement the significantly lowest enamel loss was observed in group E2. Substance loss in group E3 was significantly higher, but significantly lower compared to that of group E1. Under erosive/abrasive conditions (groups EA1–EA3), at each time point of measurement the significantly lowest enamel wear was observed in group EA2. Wear in group EA3 was significantly higher even compared to that of group EA1. The tested R.O.C.S. medical minerals gel system was able to reduce erosive enamel loss but not erosive/abrasive enamel wear, and it was less effective than the elmex erosion protection toothpaste.

Performance of a newly developed mineral gel system on erosive and erosive/abrasive enamel loss. An in vitro study

We compared the prevention of erosive and erosive/abrasive enamel loss by a medical minerals gel system (R.O.C.S.) to that by an anti-erosive toothpaste. Seventy-two bovine enamel samples were randomly allocated to six groups (E1–E3 and EA1–EA3; n=12). Per day, samples were eroded (2 min) 9 times using HCl (pH 2.6). Between erosive challenges and over night samples were stored in artificial saliva. Per day, samples were stored (100 s; groups E1–E3) or additionally brushed (20 brushing strokes; groups EA1–EA3) in/with slurries prepared from artificial saliva plus: no additional toothpaste (control groups E1 and EA1), elmex erosion protection toothpaste (groups E2 and EA2), or R.O.C.S. toothpaste (groups E3 and EA3). Once per day, samples of groups E3 and EA3 were additionally treated (40 min) with a slurry prepared from artificial saliva and R.O.C.S. medical minerals gel. After 7, 14 and 21 days enamel loss was measured by surface profilometry and analyzed by Kruskal-Wallis tests and Conover post-hoc tests. Under erosive conditions only (groups E1–E3), at each time point of measurement the significantly lowest enamel loss was observed in group E2. Substance loss in group E3 was significantly higher, but significantly lower compared to that of group E1. Under erosive/abrasive conditions (groups EA1–EA3), at each time point of measurement the significantly lowest enamel wear was observed in group EA2. Wear in group EA3 was significantly higher even compared to that of group EA1. The tested R.O.C.S. medical minerals gel system was able to reduce erosive enamel loss but not erosive/abrasive enamel wear, and it was less effective than the elmex erosion protection toothpaste.

Mechanical and surface properties analysis of restorative materials submitted to erosive challenges in situ.

Objective:This study aims to evaluate the effect of acidic solutions (AS) on surface roughness (Ra) and microhardness of restorative materials (RM).Materials and Methods:Eight volunteers wore intraoral palatal devices (IPD) containing samples of RM: Ketac Nano (KN); Ketac Nano + Biscover LV (KN-B); Esthet-X (EX); Esthet-X + Biscover LV (EX-B); Supreme XT (SXT); Supreme XT + Biscover LV (SXT-B); and bovine enamel. The samples were submitted to three phases: (1) immersion in 0.01M hydrochloric acid (HCl) – 10 min, three times/day (14 days); (2) immersion in soft drink (Sprite®) – 10 min, three times/day (14 days); and (3) keeping in saliva (14 days). Changes in Ra/microhardness were measured before/after the three phases.Statistical Analysis:ANOVA (α = 0.05) and Fisher's test.Results:Materials sealed with Biscover LV (B) presented lowest values in all periods. KN glass ionomer cement showed highest Ra values after exposure in AS. Application of B did not reduce the Ra for the composites studied, except for EX after immersion in HCl. AS promoted changes in Ra/microhardness of RM, except for sealed materials.Conclusions:The acids used were able to change the Ra and microhardness of RM, except of the sealed materials. The resin-modified GIC showed the most significant changes after immersion in AS; and the composites sealed with B, even after immersion in acidic solutions (AS), showed the lowest Ra values and the least degradation in microhardness, especially when subjected to low pH solutions.