Erosive Challenge Research Articles

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Effect of an experimental mouth rinse containing NaF and TiF4 on tooth erosion and abrasion in situ

ObjectiveThis study compared the effect of an experimental NaF/TiF4 mouth rinse with a commercial tin/F mouth rinse on the prevention of tooth wear in situ. MethodsFifteen subjects took part in this crossover and double-blind study, in which they wore a palatal appliance with 8 bovine teeth samples (4 enamel and 4 root dentine) in each of 3 phases (5 days each). Half of the samples were subjected to erosive challenges, and the other half to erosive plus abrasive challenges. The phases corresponded to the use of 1) Experimental solution containing NaF/TiF4 (189 ppm Ti+4, 500 ppm F−, pH 4.4); 2) commercial solution containing SnCl2/NaF/AmF (800 ppm Sn+2, 500 ppm F−, pH 4.5, Elmex®/GABA, positive control); 3) distilled water (negative control). Erosive challenges were performed using 0.1% citric acid (pH 2.5) for 90 s 4 times per day. The abrasion was done using a toothbrush and slurry of fluoride toothpaste, for 15 s 2 times per day. Thereafter, the subjects rinsed with the tested mouth rinse for 60s. Tooth wear was measured using contact profilometry (μm) and submitted to a two-way RM ANOVA/Bonferroni test (p < 0.05). ResultsNo significant differences were detected between the experimental and the commercial mouth rinses, regardless of the challenge. Both fluoride mouth rinses were able to significantly reduce tooth wear compared to the negative control (p < 0.0001). No significant differences were detected with respect to tooth wear between the challenges (erosion and erosion plus abrasion). ConclusionThe experimental NaF/TiF4 mouth rinse has a similar protective effect to the commercial one against tooth wear in situ. Clinical significanceThe experimental NaF/TiF4 solution protected against tooth wear in situ, regardless of the challenge (erosion or erosion plus abrasion), for both enamel and dentine, similarly to a commercial solution (tin/F-Elmex®) applied for this proposal. This result supports the conduction of clinical trials and a possible application of this solution in the future.

Precision of 655 nm Confocal Laser Profilometry for 3D surface texture characterisation of natural human enamel undergoing dietary acid mediated erosive wear

ObjectivesTo assess the precision of optical profilometry for characterising the 3D surface roughness of natural and polished human enamel in order to reliably quantify acid mediated surface roughness changes in human enamel. MethodsForty-two enamel samples were prepared from extracted human molars and either polished flat or left unmodified. To investigate precision, the variability of thirty repeated measurements of five areas of one polished and one natural enamel sample was assessed using 655nm Confocal Laser Profilometry. Remaining samples were subjected to forty-five minutes orange juice erosion and microstructural changes were analysed using Sa roughness change (μm) and qualitatively using surface/subsurface confocal microscopy. ResultsEnamel surface profilometry from the selected areas revealed maximal precision of 5nm for polished enamel and 23nm for natural enamel. After erosion, the polished enamel revealed a 48% increase in mean (SD) Sa roughness of 0.10 (0.07)μm (P<0.05), whereas in contrast the natural enamel revealed a 45% decrease in mean (SD) roughness of −0.32 (0.42)μm (P<0.05). These data were supported by qualitative confocal images of the surface/subsurface enamel. SignificanceThis study demonstrates a method for precise surface texture measurement of natural human enamel. Measurement precision was superior for polished flat enamel in contrast to natural enamel however, natural enamel responds very differently to polished enamel when exposed to erosion challenges. Therefore, thus future studies characterising enamel surface changes following erosion on natural enamel may provide more clinically relevant responses in comparison to polished enamel.

Comparative evaluation of grape seed and cranberry extracts in preventing enamel erosion: An optical emission spectrometric analysis.

Introduction:Dental erosion is defined as the loss of tooth structure due to chemical process that does not involve bacteria. The management of such a condition calls for a comprehensive approach to identifying the cause and treating it.Aim:The aim of this study is to comparatively evaluate the role of grape seed extract (GSE) and cranberry extract (CE) in preventing dental erosion using optical emission spectrometry.Materials and Methods:Prepared enamel specimens were subjected to the erosive challenge using HCl for 10 s, followed by immersion in experimental natural groups and control fluoride group for 30 s and artificial saliva for 60 min. This cycle was repeated three times. The amounts of calcium and phosphorous present in the acid solution after 1st, 2nd, and 3rd erosive challenges were determined for each group using induced coupled plasma-optical emission spectrometry.Results:The cumulative calcium and phosphorous release after the 1st, 2nd, and 3rd erosive challenges were found to be the least in SnF2 group, followed by GSE group and then in CE group.Conclusion:The protective of GSE and CE was inferior to the gold standard control group of stannous fluoride role, against enamel erosion. GSE showed better remineralizing effect; however, there was no statistically significant difference between the two groups.

Effect of two erosive protocols using acidic beverages on the shear bond strength of orthodontic brackets to bovine enamel.

Objective: To assess the short-term effect of two in vitro erosive challenge protocols on the bond strength of metal orthodontic brackets on bovine enamel. Methods: Sixty bovine incisors were selected and randomly divided into six groups: AS7 (artificial saliva - 7 days, Control Group); CC7 (Coca-Cola™ - 7 days); LJ7 (lime juice - 7 days); AS30 (artificial saliva - 30 days, Control Group); CC30 (Coca-Cola™ - 30 days); LJ30 (lime juice - 30 days). Microhardness testing was performed prior to the erosive challenge to verify the standardization of samples. Immersion was performed 4x/day for five minutes, for either 7 or 30 days. After immersions were concluded, the brackets were bonded and shear bond strength was assessed after 48 hours. The Adhesive Remnant Index (ARI) was also assessed. Data were analyzed by two-way ANOVA, followed by Tukey’s post-hoc and Student’s t test for paired samples, and the Kruskal-Wallis non-parametric test (α = 5%). Results: The mean and standard deviation of microhardness testing of total samples were 281.89 ± 44.51 KHN. There was no statistically significant difference in shear bond strength for the time factor (7 or 30 days; F5.54= 0.105; p = 0.901). However, there was a statistically significant difference for the solution factor (F5.54= 6.671; p = 0.003). These differences occurred among solutions of Saliva x Coca-Cola™ (p = 0.003) and Coca-Cola™ x Lime Juice (p = 0.029). The assessment of the Adhesive Remnant Index showed no significant difference between groups. Conclusions: The immersion time used in the erosion protocols did not affect the bond strength of brackets to teeth. Coca-Cola™ induced significantly higher shear bond strength values than lime juice and artificial saliva. However, the short term effects of 7/30 days in this in vitro study may not be extrapolated for in vivo ones. Clinical studies should be conducted, substantiating the laboratory results.

Effect of surface protection on the permeability of eroded dentin.

Context:Eroded dentin might present the opening of dentinal tubules, increasing permeability, and consequently dentinal hypersensitivity.Aims:This study evaluated the permeability of dentin surfaces exposed to different levels of erosion and methods of surface protection.Materials and Methods:Dentine samples (3 mm × 3 mm × 1 mm) were prepared from bovine incisors (n = 90) and divided into three groups according to the method of controlling erosive challenge: Negative control, topical fluoride application, and glass ionomer sealant. Subsequently, they were randomly divided into three subgroups according to the exposure of simulated gastric acid solution (Demineralization – DES) (5% HCl, pH = 2.2), and remineralization (RE); negative control, 9 and 18 cycles DES-RE. The dentin permeability was measured by assessing the hydraulic conductance (μl/min.cmH2O.cm2). Statistical analysis was performed by two-way ANOVA and Tukey's test.Results and Conclusions:Greater permeability was observed after 18 erosive cycles, followed by exposure to 9 cycles and negative control (P < 0.0001). The application of glass ionomer sealant resulted in a major reduction of the hydraulic conductivity, regardless of the erosive challenge. Control groups and topical fluoride application showed similar results. In conclusion, the severity of erosive challenge contributed to the increase of dentin permeability. Besides, the glass ionomer sealant was the only protection agent that promoted significant effects in dentin permeability.

The effect of aspartame and pH changes on the erosive potential of cola drinks in bovine enamel: An in vitro study.

BackgroundThe aim of this study was to clarify the mechanism behind the different erosive potential of regular and light cola drinks: pH difference and/or aspartame presence.Material and MethodsSixty bovine enamel blocks were randomly divided into 5 groups: RC - regular cola, RCpH - addition of base to increase regular cola pH, RCAS - addition of aspartame to regular cola, LC - light cola, and LCpH - addition of acid to decrease light cola pH. Two-thirds of the blocks surface was coated with nail varnish for reference. The samples were daily subjected to four erosive challenges for 2 minutes. Between the erosive challenges (2h) and overnight the samples were maintained in artificial saliva. The response variable was the percentage surface hardness change (%SHC) after 1st experimental day and enamel surface loss (µm) measured at the 5th day by profilometry. Data were analyzed by ANOVA and Tukey’s test (p<0.05).ResultsIndependently of the cola modifications, all groups promoted similar hardness change of enamel surface. RC promoted higher enamel loss (6.69±0.71µm) than LC (4.80±0.77µm). The acid addition to light cola (LCpH: 6.60±1.78µm) significantly enhanced its erosive potential, which did not differ from RC. The base addition to regular cola (RCpH-4.00±0.64µm) resulted in similar wear to LC. The addition of aspartame to the regular cola (RCAS 5.44±0.65µm) resulted in similar wear to LC and RC.ConclusionsThe data suggest that the pH alteration has a major impact on the erosive potential of cola drinks, however, the sweetener also has some influence. Key words:Tooth erosion, dental enamel, soft drinks, ph, sweetener.

Evaluation of Remineralization Potential of Beverages modified with Casein Phosphopeptide-Amorphous Calcium Phosphate on Primary and Permanent Enamel: A Laser Profiler Study.

PurposeTo assess the erosive potential of carbonated beverages and the remineralization potential of beverages with added casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on primary and permanent enamel.Materials and methodsA total of 32 primary and 32 permanent enamel specimens were immersed for 5, 10, and 30 minutes, respectively, in beverages, i.e., Coke, Sprite, Mirinda, and Mountain Dew, with and without added 0.2% CPP-ACP. Samples were profiled before immersion and after immersion under laser profiler.ResultsCoke was found to be highly erosive at it caused significant enamel erosion at both 10 and 30 minutes of immersion (p < 0.05) for both primary and permanent enamel. The 30-minute immersion caused significant amount of reminerali-zation over primary enamel in all groups, whereas permanent enamel remineralization was significant in Sprite and Mountain Dew at 30 minutes in all the groups (p < 0.05).ConclusionThis study demonstrated that enamel erosion occurred after immersion in carbonated beverages. Remineralization of enamel was observed after immersion in beverages modified with CPP-ACP paste. Primary enamel was susceptible to remineralization compared with permanent enamel. Within the limitations of this in vitro study, the application of CPP-ACP paste may enhance the remineralization after an erosive challenge and thus offer some protection for patients who are at risk for erosion.How to cite this article: Rai N, Sandhu M, Sachdev V, Sharma R. Evaluation of Remineralization Potential of Beverages modified with Casein Phosphopeptide-Amorphous Calcium Phosphate on Primary and Permanent Enamel: A Laser Profiler Study. Int J Clin Pediatr Dent 2018;11(1):7-12.

Erosive, abrasive and erosive-abrasive challenges: Effect on ceramic materials

Erosive, abrasive and erosive-abrasive challenges: Effect on ceramic materials

Effect of erosion and methods for its control on the surface roughness of composite resin

Objective: This study evaluated the surface roughness of a nanofilled composite resin submitted to different degrees of erosion and methods of control.Methods: 120 cylindrical composite specimens (6×1.5 mm) were randomly divided into four groups, according to the surface protection against the erosive challenge [negative control, topical application of fluoride, glass-ionomer sealant, resin sealant]. After the application of the respective method, specimens were divided into three subgroups (n=10): a) absence of erosive challenge; b) 9 cycles of DES-RE; c) 18 cycles of DES-RE. Surface roughness (Ra, μm) was recorded and statistically analyzed (2-way Anova/Tukey).Results: The glass-ionomer sealant exhibited less rough surfaces under all the conditions. However, the average roughness was significantly higher after 18 DES-RE cycles.Conclusion: Despite the potential shown by glass-ionomer sealant, it was concluded that no material prevented an increase in surface roughness of the nanofilled composite after an intense erosive challenge.

The effect of magnesium hydroxide-containing dentifrice using an extrinsic and intrinsic erosion cycling model

ObjectiveTo evaluate, in vitro, the effect of Mg(OH)2 dentifrice, and the influence of the number of experimental days, on the extrinsic (citric acid –CA) and intrinsic (hydrochloric acid –HCl) enamel erosion models. DesignHuman enamel slabs were selected according to surface hardness and randomly assigned to 3 groups (n=9) as follows: non-fluoridated (negative control), NaF (1450ppm F- positive control) and Mg(OH)2 (2%) dentifrices. The slabs were daily submitted to a 2-h period of pellicle formation and, over a period of 5days, submitted to cycles (3×/day) of erosive challenge (CA 0.05M, pH=3.75 or HCl 0.01M, pH=2 for 30s), treatment (1min −1:3w/w of dentifrice/distilled water) and remineralization (artificial saliva/120min). Enamel changes were determined by surface hardness loss (SHL) for each day and mechanical profilometry analysis. Data were analyzed by two-way ANOVA followed by Tukey’s test to % SHL and one-way ANOVA to profilometry (p<0.05). ResultsThe number of experimental days influenced the erosion process for the two types of erosion models (p<0.001). Mg(OH)2-containing dentifrices were effective in reducing enamel extrinsic acid erosion as determined by % SHL (p<0.001) when compared to the control group, being better than positive control (p<0.001); however, the dentifrices were not effective for the intrinsic model (p=0.295). With regards to surface wear, no statistically significant differences were found among the groups for CA (p=0.225) and HCl (p=0.526). ConclusionThe findings suggest that Mg(OH)2 dentifrices might protect enamel against slight erosion, but protection was not effective for stronger acid erosion.

Er,Cr:YSGG Laser Energy Delivery: Pulse and Power Effects on Enamel Surface and Erosive Resistance.

High power lasers have been suggested as a useful tool for dental caries and erosion prevention due to the increase of enamel acid resistance. to evaluate the effect of Er,Cr:YSGG (erbium,chromium:yttrium, scandium, gallium, garnet) laser irradiation pulse frequency and power on enamel surface and acid erosion resistance. By combining pulse frequency (5-75 Hz) and power settings (0.10-1.00 W), 20 irradiated groups and one nonirradiated control group were tested. A total of 63 bovine enamel blocks (n = 3/group) were prepared for surface hardness and roughness evaluation, performed in three phases: baseline, after irradiation, and after erosive challenge. Enamel blocks were irradiated with Er,Cr:YSGG laser with MZ8 tip (iPlus; Waterlase, Biolase, CA) for 30 sec according to experimental group and submitted. Erosive challenge consisted of four cycles alternating immersion in 0.01 M HCl (5 mL/mm2; 2 min; at 37°C) and immersion in artificial saliva for 3 h. Analysis of variance (three-way ANOVA), Tukey's test, and Pearson correlation were performed for the statistical analysis (p < 0.05). After irradiation, groups irradiated with pulse frequency of 10 and 15 Hz showed a decrease in surface hardness. After erosive challenge, 5 and 75 W groups showed increase in surface hardness; 0.25, 0.5, 0.75, and 1 W groups showed minor alterations in surface roughness. the irradiation of Er,Cr:YSGG laser with different parameters of power and pulse frequency settings may alter enamel surface and erosive resistance differently. Pulse frequency of 30 Hz and power of 0.50 W was considered the best parameter to prevent enamel acid erosion.

Fluoride toothpastes containing micrometric or nano-sized sodium trimetaphosphate reduce enamel erosion in vitro

Objective: To evaluate the effect of fluoride toothpastes supplemented with micrometric or nano-sized sodium trimetaphosphate (TMP or TMPnano, respectively) on enamel erosion in vitro, as well as the influence of salivary acquired pellicle and saliva.Material and methods: Bovine enamel blocks (n = 120) were randomly assigned into the following experimental toothpastes: no F/TMP/TMPnano (Placebo); 1100 ppm F (1100 ppm F); 1100 ppm F plus 3% TMP or 3% TMPnano (1100 TMP or 1100 TMPnano, respectively) and 5000 ppm F (5000 ppm F). Erosive challenge was performed by immersion of the blocks in citric acid for 5 min, followed by 2 h immersion in human or artificial saliva, 4×/day, during 5 days. After each erosive challenge, blocks were exposed to slurries of the toothpastes. Enamel erosion (µm), surface hardness (SHf) and cross-sectional hardness (ΔKHN) were analyzed as response variables and the data were submitted to two-way ANOVA, followed by the Student–Newman–Keuls test (p < .05).Results: 1100 TMPnano significantly reduced enamel loss when compared to 1100 TMP (p = .002), reaching values similar to those promoted by 5000 ppm F (p = .96). 1100 ppm F presented significantly lower enamel loss than Placebo (p < .001), and higher than 1100 TMP (p < .001). Significantly higher SHf and lower ΔKHN was observed for 1100 TMPnano and 5000 ppm F when compared with the other groups (p < .001). The type of saliva did not influence enamel erosion, SHf and ΔKHN for the groups treated with TMP-containing toothpastes.Conclusion: The addition of 3% TMPnano to 1100 ppm F toothpastes significantly increases the protective effect against enamel erosion in vitro when compared with its counterparts with micrometric TMP or without TMP. This effect was not influenced by the presence of acquired enamel pellicle and saliva.

The effect of different salivary calcium concentrations on the erosion protection conferred by the salivary pellicle

Different proportions of mineral ions in saliva can influence the protective effect the salivary pellicle provides against dental erosion. To investigate the effect of different calcium concentrations in human saliva on the protection against enamel erosion, enamel specimens were divided into 8 treatment groups: humid chamber (Ctrl); whole mouth stimulated human saliva (HS); artificial saliva containing different calcium concentrations (ASlow, ASmedium, AShigh); and dialysed human saliva containing different calcium concentrations (DSlow, DSmedium, DShigh). The specimens underwent 4 cycles of incubation in the treatment group followed by an erosive challenge. Surface hardness and calcium release were measured during the cycling process. All DS groups exhibited significantly higher enamel surface softening than HS and the corresponding AS groups. Among the DS groups, the surface softening was significantly higher in DSlow than in DShigh. No significant differences were found within the AS or DS groups regarding calcium release. The results of this study indicated that erosion protection conferred by saliva depends on an interplay between salivary proteins and ions. While both proteins and ions have a positive effect on their own, the combination of the two can lead to different degrees of protection or even negative effects, depending on the relative concentrations.

A Novel Kinetic Method to Measure Apparent Solubility Product of Bulk Human Enamel.

Introduction: Tooth enamel mineral loss is influenced by its solubility product value, which is fundamental to the understanding of de- and remineralization resulting from a carious or erosive challenge. Published pKsp values for human enamel and hydroxyapatite range from 110 to 126 suggesting a heterogeneous nature of enamel solubility. However, this range of values may also result from the variety of methods used, e.g., some authors reporting values for suspensions of enamel powder and others for bulk enamel. The aim of this study was to develop a method to measure the solubility of bulk human enamel under controlled in vitro conditions simulating demineralization behavior of enamel within the oral environment using scanning microradiography (SMR). SMR was used to monitor real-time changes in enamel demineralization rates at increasing calcium concentrations in a caries simulating demineralization solution until the concentration at which thermodynamic equilibrium between enamel and solution was achieved.Method: 2 mm thick caries free erupted human enamel slabs with the natural buccal surfaces exposed were placed in SMR cells exposed to circulating caries-simulating 2.0 L 0.1 M pH = 4.0 acetic acid, at 25°C. SMR was used to continuously measure in real-time the decrease in mineral mass during the demineralization at 5 different points from on each slab. Demineralization rates were calculated from a linear regression curve of projected mineral mass against demineralization time. Changes in the demineralization rates were monitored following a series of successive increases in calcium (and phosphate at hydroxyapatite stoichiometric ratios of Ca:P 1.67) were added to the demineralizing solution, until demineralization ceased. The pH was maintained constant throughout.Results: Demineralization halted when the calcium concentration was ~30 mM. At higher calcium concentrations, mineral deposition (remineralization) occurred. By comparison with results from speciation software calculations for the calcium phosphate ternary system, this result suggests that the bulk solubility product of enamel (pKspBEnamel) under the conditions used is 121.Discussion: The apparent pKspBEnamel under these conditions was higher than many previous reported values, and much closer to those previously reported for HAp. However, this is a bulk value, and does not reflect that enamel is a heterogeneous material, nor the influence of ionic inclusions.

Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15): GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3) for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (p<0.05). The result showed no statistically significant difference between groups (GS = 14.60±2.86 and GE = .14.69±2.21 μm). The presence of initial erosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

Quantitative Swept-Source Optical Coherence Tomography of Early Enamel Erosion in vivo

Swept-source optical coherence tomography (SS-OCT) shows potential for the in vivo quantitative evaluation of micro-structural enamel surface phenomena occurring during early erosive demineralization. This randomized controlled single-blind cross-over clinical study aimed to evaluate the use of SS-OCT for detecting optical changes in the enamel of 30 healthy volunteers subjected to orange juice rinsing (erosive challenge) in comparison to mineral water rinsing (control), according to wiped and non-wiped enamel surface states. Participants were randomly allocated to 60 min of orange juice rinsing (pH 3.8) followed by 60 min of water rinsing (pH 6.7) and vice versa, with a 2-week wash-out period. In addition, the labial surfaces of the right or left maxillary incisors were wiped prior to SS-OCT imaging. An automated ImageJ algorithm was designed to analyse the back-scattered OCT signal intensity (D) after orange juice rinsing compared to after water rinsing. D was quantified as the OCT signal scattering from the 33 µm sub-surface enamel, normalised by the total OCT signal intensity entering the enamel. The back-scattered OCT signal intensity increased by 3.1% (95% CI 1.1-5.1%) in the wiped incisors and by 3.5% (95% CI 1.5-5.5%) in the unwiped incisors (p < 0.0001). Wiping reduced the back-scattered OCT signal intensity by 1.7% (95% CI -3.2 to -0.3%; p = 0.02) in comparison to the unwiped enamel surfaces for both rinsing solutions (p = 0.2). SS-OCT detected OCT signal changes in the superficial sub-surface enamel of maxillary central incisor teeth of healthy volunteers after orange juice rinsing.

Teaching psychology to nursing students-a discussion of the potential contribution of psychology towards building resilience to lapses in compassionate caring.

Psychology is a required element in nursing education in many countries. It is particularly aimed at teaching nursing students to get a better understanding of patients, colleagues, health care organizations and themselves, and moreover to apply what they learn about psychology to optimise their care. A meaningful integration of psychology within nursing education requires an emphasis on its application in understanding aspects of care and skills development. However, its ultimate value is demonstrated when addressing problem areas in nursing and health care. In this paper the authors outline an approach to psychology education in nursing which emphasises its development as a problem solving support. An example is presented which focuses on the application of psychology to the challenge of care erosion and deficient critical nursing reflection. The discussion includes the organisational context, social pressure, social cognition, reflection and the role of inner conflict (cognitive dissonance). Nursing educators can contribute to the prevention of care erosion by a combined effort to teach awareness of psychological mechanisms, 'critical' reflection, mastery in practice, strong values and standards, and 'inoculation' against justifications of substandard care.

Effect of gels containing chlorhexidine or epigallocatechin-3-gallate on the protein composition of the acquired enamel pellicle

ObjectiveThis study evaluated changes in protein profile of the acquired enamel pellicle (AEP) formed in vivo, after application of gels containing chlorhexidine or EGCG and further challenge with citric acid. DesignAEP was formed in 9 volunteers for 2h and then treated with one of the following gels: placebo, 400μM EGCG or 0.012% chlorhexidine. A thin layer of gel was applied and after 1min the excess was removed. One hour after gel application, the AEP was collected from the buccal surface (upper and lower jaw) of one of the sides with filter paper dipped in 3% citric acid. On the other side, erosive challenge was performed through gentle application of 1% citric acid (pH 2.5) for 20s (using a pipette) followed by washing with deionized water. The AEP was collected as mentioned before. Proteomic analysis was performed through liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI–MS/MS). The MS/MS spectra obtained were compared with human protein databases (SWISS-PROT). Label-free quantitation was done using the PLGS software. ResultsIn total, 223 proteins were identified. After treatment with EGCG and CHX gels, proteins with potential functions to protect against caries and erosion such as PRPs, calcium-bind proteins and Statherin were increased. When EGCG and CHX-treated AEPs were challenged with citric acid, there was increase in cystatins and Profilin-1. ConclusionCHX- and EGCG-treated AEPs, submitted to challenge with citric acid or not, had remarkable changes in their proteomic profiles.