The influence of different factors on in vitro enamel erosion

Effect of acidic media on surface characteristics of highly filled flowable resin-based composites: An in vitro study

OBJECTIVE

To analyze and compare the impact of acidic media on the surface characteristics of highly filled flowable resin-based composites.

MATERIALS AND METHODS

Two hundred fifty-six specimens were divided into four groups: GUF (G-aenial Universal Flo), GUI (G-aenial Universal Injectable), TEF (Tetric EvoFlow), and FSF (Filtek Supreme Flowable Restorative). Surface characteristics were analyzed before (T0) and after specimens immersion in different media, such as gastric juice (GJ), fizzy drink (FD), citric juice (CJ), or artificial saliva (AS), for 9 h (T1) and 18 h (T2). The analyses included surface roughness (SR) measurements, where average roughness (Ra) was obtained, scanning electron microscopy (SEM) analysis, and surface hardness (SH) evaluation, with Vickers numbers (HV) reported. The differences in values among groups/subgroups within the same stage were assessed using two-way ANOVA and Tukey's post hoc test, whereas repeated measures ANOVA with Bonferroni post hoc test was performed to compare the changes in values through the stages. Data were presented as mean ± standard deviation (SD).

RESULTS

At T0, GUI and GUF revealed lower Ra values (p < 0.05), more evenness in SEM micrographs, and higher HV values (p < 0.05) than FSF and TEF. At T1 and T2, specimens of all groups/subgroups demonstrated an increase in Ra and a decrease in HV compared with T0 (p < 0.05), as well as the changes in surface morphology on SEM micrographs. The lowest Ra and highest HV values were observed in GUI group, in contrast to FSF group, and in specimens immersed in GJ.

CONCLUSIONS

GUI revealed lower SR and higher SH compared to GUF and FSF both before and after exposure to acidic media. The presence of acidic media, especially GJ, significantly increases SR and decreases SH of tested materials.

CLINICAL SIGNIFICANCE

Information on the changes in the surface characteristics of highly filled resin-based composites after exposure to acidic media may be essential for the longevity of restorations like composite veneers fabricated from these materials.

Morphological study of remineralization of the eroded enamel lesions by tyrosine-rich amelogenin peptide

BACKGROUND

Tyrosine-rich amelogenin peptide (TRAP) is the main amelogenin digestion product in the developmental enamel matrix. It has been shown to promote remineralization of demineralized enamel in our previous study. However, direct evidence of the effect of TRAP on the morphology and nanostructure of crystal growth on an enamel surface has not been reported. This study aimed to examine the effect of TRAP on the morphology of calcium phosphate crystals grown on early enamel erosion using a pH-cycling model.

METHODS

Eroded lesions were produced in human premolars by 30-second immersion in 37% phosphoric acid. Forty-five samples of eroded human premolar enamel blocks were selected and randomly divided into 3 groups: deionized water (DDW, negative control); 100 µg/mL TRAP, and 2 ppm sodium fluoride (NaF, positive control group). For 14 days, the specimens were exposed to a pH-cycling model. Using scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods, the surface morphology, calcium-phosphorus ratio, and enamel surface roughness were examined. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to assess crystal characteristics.

RESULTS

After pH-cycling, compared to the two control groups, the surface of the eroded enamel of the peptide TRAP group shows a large number of new, densely arranged rod-like crystals, parallel to each other, regularly arranged, forming an ordered structure, with crystal morphology similar to that of natural enamel. The crystals are mostly hydroxyapatite (HA).

CONCLUSION

This study demonstrates that the peptide TRAP modulates the formation of hydroxyapatite in eroded enamel and that the newly formed crystals resemble natural enamel crystals and promote the remineralization of enamel, providing a promising biomaterial for remineralization treatment of enamel lesions.

Cervical wear pathobiology by robot-simulated 3-year toothbrushing - New methodological approach

OBJECTIVES

An ex-vivo study was aimed at (i) programming clinically validated robot three-year random toothbrushing, (ii) evaluating cervical macro- and microwear patterns on all tooth groups of different functional age, (iii) documenting and codificating wear related morphological features at the cemento-enamel junction in young teeth and on roots in older teeth.

DESIGN

Following ethical approval random toothbrushing (44 strokes per tooth horizontally, rotating, vertically; 2x/d) with manual toothbrushes and low-abrasive dentifrice was performed in an artificial oral cavity with brushing-force 3.5 N on 14 extracted human teeth. Morphological features were examined by SEM at baseline and after simulated 3 years using the replication technique. 3D-SEM analyses were carried out with a four-quadrant back scattered electron detector. Wilcoxon-Mann-Whitney-test was used for statistical analyses.

RESULTS

3-year random toothbrushing with horizontal, rotating and vertical brushing movements revealed morphological features classified as four enamel patterns, one dentin pattern and three cervical patterns. Negative impacts were enamel, cementum and dentin loss. Positive impact on oral health was removing dental calculus and straightening cervical traumatic and iatrogenic damages. The volume loss varied from x̅=34.25nl to x̅=87.75nl. Wear extended apically from 100 to 1500 micrometres.

CONCLUSION

Robot simulated toothbrushing in an artificial oral cavity, with subsequent SEM and 3D-SEM assessment, elucidated both negative and oral health-contributing micromorphology patterns of cervical wear after simulated 3-year random toothbrushing. Cervical macro- and microwear of cementum revealed, for the first time, what we describe as overhanging enamel peninsulas and enamel islands on roots in young teeth, but no enamel islands on roots from older teeth after root cementum loss. In contrast, many older teeth exhibited enamel peninsulas.

Enamel Remineralisation with a Novel Sodium Fluoride-Infused Bristle Toothbrush

This study aims to investigate whether toothbrushes with fluoride-infused bristles have any (re)mineralisation effects on bovine enamel. Bovine incisors (N = 160) were extracted, and the buccal side of the crown was cut into dimensions of ~5 mm × 5 mm with a low-speed saw. These specimens were randomly allocated into four groups: half (80 teeth) were stored in demineralising solution (DM), and the other half were stored in deionised water (DW) for 96 h. Then, they were brushed with a force of 2.0 ± 0.1 N for five min with a manual toothbrush with either fluoride-infused (TF) or regular (TR) bristles. Microhardness (Vickers), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were used to investigate the surfaces of the bovine enamel specimens before and after brushing. Two-way ANOVA was used to analyse the hardness data, and the pairwise comparison method was used to analyse the Ca/P ratio, for each group at α = 0.05. The results show that brushing with either of these toothbrushes increased the Vickers microhardness on DM and DW enamel (p < 0.001), whereas hydroxyapatite was revealed in all groups by XRD. The DM samples showed a significant increase (p < 0.05) in the Ca/P ratios after brushing with TR and TF. Conversely, under DW conditions, these ratios decreased significantly after brushing. In terms of the F atomic%, TF increased significantly. SEM revealed mineral deposition in the DM groups after toothbrushing. To conclude, toothbrushing effectively induces the microhardness of sound and demineralised enamel, while fluoride-infused bristles might be able to retain fluoride on the enamel surface.

In Vitro Risk Assessment of Dental Acid Erosion Caused by Long-Term Exposure to Oral Liquid Bandages

Oral mucosa inflammation can cause severe pain and interfere with eating, reducing quality of life. However, few options for self-care are available. An oral liquid bandage forms a protective film over the affected area. We aimed to assess the acid erosion risk when a newly developed oral liquid bandage (ORAPLA) is accidentally deposited on teeth and to examine the relative acid erosion risk at multiple time points of the maximum recommended duration of continuous use. ORAPLA was applied to both enamel and dentin blocks from 45 bovine anterior mandibular teeth, and an acid challenge was performed in a simulated oral cavity with artificial saliva, with one exposure cycle lasting 6 h. The enamel showed substantial defects and a decrease in Vickers hardness after nine cycles, with no change in surface roughness. Dentin showed an increase in parenchymal defects and surface roughness and a trend toward decreased Vickers hardness with increasing exposure time. We found no significant acid corrosion in enamel after up to nine times the upper limit of normal use time or in dentin after up to six times the upper limit. We conclude that the acid erosion risk due to accidental attachment to teeth is low, and in the human oral cavity with salivary buffering and remineralization, likely even lower.

Dental evaluation is helpful in the differentiation of functional heartburn and gastroesophageal reflux disease

BACKGROUND

Heartburn is identically the key symptom of both, gastroesophageal reflux disease (GERD) and functional heartburn (FHB), making the differential diagnosis resource-intensive. Oral manifestations of GERD can be easily examined; therefore, their exploration might be a cheap, widely available, and useful tool in the differentiation of GERD and FHB.

AIM

To evaluate the prevalence of dental erosions (DE) and periodontal diseases (PD) in patients with heartburn and their association with GERD and FHB.

METHODS

A total of 116 [M/F: 51/65, mean age: 54 (17-80) years] consecutive patients with heartburn were enrolled for detailed esophageal function and orodental examinations.

RESULTS

Dental disorders were detected in 89% (103/116). Patients with PD + DE had significantly more often pathologic reflux (90.0% vs 27.8%; P < 0.05), higher esophagitis scores (1.8 vs 0.9; P < 0.05), and a significantly different mean impedance curve (P = 0.04) than those without any dental diseases. The opposite approach established that patients with GERD had significantly higher prevalence of DE and PD, especially if both were present (28.9% vs 2.0%; P < 0.01), more severe PD (1.5 vs 1.0; P < 0.01), and longer history of heartburn (15 years vs 9 years; P < 0.01) than those with FHB.

CONCLUSION

The dental evaluation of patients with heartburn seems to be useful in the differential diagnosis of GERD and FHB. Among the studied parameters, the co-appearance of DE and PD seems to be the best predictor of GERD, whereas the absence of dental disorders was mostly observed in FHB.

The dynamic interplay of dietary acid pH and concentration during early-stage human enamel and dentine erosion

Dental erosion continues to be a significant global health concern affecting nearly 30% of adults world-wide. With increasing soft drink consumption predominantly driving its prevalence, strategies for prevention and control are often implemented when erosion is severe, or rates are high in the populace. While factors affecting dental erosion such as pH on enamel has received much attention, the effect of dietary acid concentration when factored out to a commercially available pH has yet to be determined. Furthermore, understanding these effects on dentine, which is known to be more susceptible to erosion than enamel can unravel structure property relationships between acid characteristics and hard tissue types. This study aimed to develop structure-property relationships between dietary acid concentration, and pH, on the nano-textural and nano-mechanical properties of human enamel and dentine during short-term simulated drinking. To achieve this, a novel sample preparation methodology and analysis approach was developed by applying atomic force microscopy (AFM) in quantitative imaging mode. This enabled simultaneous measurement of enamel and dentine morphology and mechanical properties. Flow-cells were used to simulate drinking, exposing polished and smear layer free human enamel and dentine to 30 s repeated cycles of unbuffered citric acid 6% (pH = 1.88) and 1% (w/v) (pH = 2.55) and commercially available buffered pH = 3.8 states, for up to 180 s. The same 50 µm × 50 µm area of specimen morphology was analysed using in-house developed nanotextural analysis using the bearing area curve (BAC) with a focus on roughness (Ra), normalised peak (PA) and valley areas (VA). Mechanical properties were simultaneously measured for stiffness (N/m) after each 30 s. While all studies agree pH is a major factor in the erosion of enamel, here its dominance over the treatment time varied, with concentration surpassing the importance of pH after initial acid contact. Conversely, dentine erosion showed concentration-dependent changes in morpho-mechanical properties only. These results not only highlight the dynamic process of erosion, but how the interplay between acid characteristics and dental tissue type impact the progression of very early-stage erosion.

pH analysis of still and carbonated bottled water: Potential influence on dental erosion

Objective

To assess pH values to characterize bottled water in Portugal, being able to provide information for both patients and clinicians about its erosive potential, as a tool to prevent the ingrowing prevalence of dental erosion and its progression, especially in patients who are at greater risk, such as those with dry mouth syndrome, making the dissemination of this knowledge a fundamental tool for clinical decision.

Materials and Methods

One hundred and five common brands of bottled water (n = 105), commercialized in Portugal, were analyzed. Of these, 73 were smooth water (Group A) and 32 carbonated water (Group B). All pH values were assessed by potentiometric measurement with a calibrated electrode. For each brand, five independent measurements were recorded at 25°C for further calculation of the mean pH value and standard deviation.

Results

Focusing on the mean pH values from Group A, one had a pH mean value lower than 5.2, four between 5.2 and 5.5, thirty‐seven between 5.5 and 6.8, and thirty‐one higher than 6.8. In Group B, ten had a mean pH value lower than 5.2, ten between 5.2 and 5.5, twelve between 5.5 and 6.8, and none above 6.8.

Conclusions

Bottled water, commercialized in Portugal, has different mean pH values, some below the critical threshold of enamel and/or dentin, suggesting that they may have a greater risk of consumption than others, only with respect to the pH parameter of erosive potential. Further investigation concerning this area is needed for wider conclusions.

Atomic force microscopy analysis of the surface alterations of enamel, dentin, composite and ceramic materials exposed to low oral pH in GERD

Dental erosion is a significant topic in medical literature, both for gastroenterology and dental medicine. Dental structure loss has a psychosocial and functional significance. The pathogenesis of dental erosion in patients diagnosed with gastroesophageal reflux disease (GERD) characterized by the presence of an acidic oral environment after reflux episodes, is not well understood. The present study was designed to observe the effect of low oral pH in time on natural surfaces including enamel and dentine, but also on materials used in treating these dental destructions such as composites and ceramics. The acidic oral environment was estimated in relation to salivary pH. In the dental laboratory, 5-mm2 and 1-mm composite pieces of thick enamel, dentine, Emax Ceramic and Nexco Ivoclar were cut in order to be analyzed using atomic force microscopy (AFM) and to observe the surface alterations. Gastric acid was collected and mixed with saliva until a pH value of 6.0 was obtained, in which the pieces were immersed for 24, 120, 240 h. Roughness of each surface was calculated at a microstructure and nanostructure level. The results showed significant alterations in enamel and dentine exposed to a lower pH level beginning even at a short immersion time, in comparison with composites and ceramics which had no alterations. In conclusion, multidisciplinary attention should be given to detect and manage acidity of the oral cavity caused by GERD, in order to prevent dental erosion.

The effect of red wine in modifying the salivary pellicle and modulating dental erosion kinetics

This study investigated the potential of red wine in modulating dental erosion kinetics in the presence or absence of salivary pellicle. Polished human enamel specimens were used in two conditions; presence or absence of acquired enamel pellicle; and subdivided according to exposure: red wine, orange juice, apple juice, or citric acid. The specimens were incubated in clarified whole human saliva (presence of acquired enamel pellicle) or in a humid chamber (absence of acquired enamel pellicle) for 2 h at 37°C, then in the test substances for 1 min, at 25°C, under shaking. This was repeated four times. Surface hardness was measured initially and after each cycle and surface reflection intensity was measured initially and after all cycles. In the presence of acquired enamel pellicle, red wine caused the least surface hardness loss, followed by orange juice, apple juice, and citric acid. Statistically significantly less surface reflection intensity loss was observed for red wine and orange juice than for apple juice and citric acid. In the absence of acquired enamel pellicle, red wine and orange juice caused less surface hardness loss than apple juice and citric acid. Orange juice showed the least surface reflection intensity loss, followed by red wine, citric acid, and apple juice. The polyphenol composition of these drinks can notably modulate the erosion kinetics.

Solution properties and comparative antimicrobial efficacy study of different brands of toothpaste of Nepal

Background

The main objective of this study is to compare the effectiveness of toothpaste formulations in giving total protection to the oral cavity. So, three important solution properties: surface tension, conductivity, and pH measurements, have been investigated for eight kinds of commercial herbal and non-herbal based toothpaste of Nepal. The study was extended to evaluate the antibacterial efficacy of toothpaste formulations against the Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli), and this was done by standard agar well diffusion technique. Amikacin (30 μg/disk) was used as a positive control to compare the antibacterial potency of the investigated toothpaste.

Results

The surface tension of all toothpaste formulations increased with the decrease in concentration. However, the conductivity of the formulations decreased with the decrease in concentration. The highest pH of 8.24 was recorded for Dabur Super Salt (DSS) and all values were found to be higher in tap water solutions. All toothpaste formulations showed significant growth inhibition against both S. aureus and E. coli. The overall antibacterial sensitivity of Dabur Red (DR) is higher for S. aureus. The solid material content was found to be highest for Dabur Herbal Gel (DHG) and lowest for Pepsodent (PD).

Conclusion

The findings of the present study showed all toothpaste formulations as effective in inhibiting the growth of tested bacterial species. Toothpaste formulations were found slightly alkaline, which favors bacterial growth inhibition. Increasing surface tension and decreasing conductivity value of toothpaste relative to a decrease in concentration favor its desirable cleansing action.

In situ efficacy of an experimental toothpaste on enamel rehardening and prevention of demineralisation: a randomised, controlled trial

Background

A novel sodium fluoride toothpaste containing lactate ion and polyvinylmethylether-maleic anhydride has been developed to promote enamel remineralisation and resistance to demineralisation. In this in situ study, we compared this toothpaste (‘Test’) with a stannous fluoride-zinc citrate (SnF₂-Zn) toothpaste (‘Reference’) (both 1100–1150 ppm fluoride) and a fluoride-free toothpaste (‘Placebo’) using an enamel dental erosion-rehardening model.

Methods

In each phase of this randomised, investigator-blind, crossover study, participants wore palatal appliances holding bovine enamel specimens with erosive lesions. They brushed their natural teeth with either the Test, Reference or Placebo toothpastes, then swished the resultant slurry. Specimens were removed at 2 h and 4 h post-brushing and exposed to an in vitro acid challenge. Surface microhardness was measured at each stage; enamel fluoride uptake was measured after in situ rehardening. Surface microhardness recovery, relative erosion resistance, enamel fluoride uptake and acid resistance ratio were calculated at both timepoints.

Results

Sixty two randomised participants completed the study. Test toothpaste treatment yielded significantly greater surface microhardness recovery, relative erosion resistance and enamel fluoride uptake values than either Reference or Placebo toothpastes after 2 and 4 h. The acid resistance ratio value for Test toothpaste was significantly greater than either of the other treatments after 2 h; after 4 h, it was significantly greater versus Placebo only. No treatment-related adverse events were reported.

Conclusions

In this in situ model, the novel-formulation sodium fluoride toothpaste enhanced enamel rehardening and overall protection against demineralisation compared with a fluoride-free toothpaste and a marketed SnF₂-Zn toothpaste.

Trial registration

ClinicalTrials.gov; NCT03296072; registered September 28, 2017.

Factors associated with dental erosions in gastroesophageal reflux disease: a cross-sectional study in patients with heartburn

BACKGROUND AND AIM

Dental erosion (DE) represents a frequent condition in adults and the elderly. The gastroesophageal reflux disease (GERD) is considered an important endogenous factor causing dental erosions. The objective of this study was to assess the prevalence of DE in GERD patients and to establish the correlation between pathogenic intrinsic and extrinsic factors of DE and their relation to GERD.

METHODS

A cross-sectional study was conducted on 263 patients (median age 43). Patients with heartburn were recruited in two countries with different prevalence of GERD. Patients were recruited from France (n=158, 60%) and Romania (n=105, 40%) including 163 females and 100 males. The Basic Erosive Wear Examination (BEWE) index for diagnosis and evaluation of dental erosion was used. Based on the value of BEWE score, each patient was included in a risk group for DE development (low risk: BEWE=3-8, medium risk: BEWE=9-13, high risk: BEWE ≥14). Patients filled a questionnaire regarding GERD symptoms, medications, life style. Salivary parameters (pH and buffering capacity) were also assessed and analyzed.

RESULTS

DE was significantly more frequent and more severe in GERD subjects than in the non-GERD controls. Low salivary pH but not salivary buffering capacity was associated with BEWE scores. Buffering capacity however was significantly more altered in patients with BEWE score over 9 (medium DE) than in patients with mild DE (BEWE <9). Although extrinsic factors (consumption of citrus fruits, soda drinks) were associated with DE in GERD, there was no statistical correlation with the BEWE score. From the total of 263 patients, 229 (87.1%) presented BEWE score <9, and 34 (12.9%) presented BEWE ≥9. The DE was significantly associated with the presence of GERD (p<0.001). BEWE score >9 was more frequently present in GERD patients (30 patients: 21.3%) than in non GERD patients (4 patients: 3.3%). DE were more frequent in French subjects compared to Romanian subjects. Romanians had lower BEWE scores than the French.

CONCLUSIONS

DE is more frequent and more severe with GERD vs. non-GERD. DE in GERD is associated with extrinsic dietary factors like citrus fruits and soda drinks.

Dissolution of Enamel on Exposure to Various Commercial Beverages Available in India

AIM

The study was aimed to estimate the pH of the commonly available soft drinks in the Indian market and to assess the detrimental effects of the juices and beverages on the tooth surface by measuring the weight loss of the tooth sample.

MATERIALS AND METHODS

The study was done with eight different types of commercially available carbonated drink and fruit juices available in the Indian market among which six were carbonated drinks and two were juices. Carbonated drinks experimented were Coca-Cola, Pepsi, Fanta, Mirinda, 7Up and Sprite, and two fruit juices were Tropicana orange juice and real orange juice. Ten different bottles from each category were obtained, and the pH was estimated. Each of the beverages was divided into batch of 10 containers containing the tooth sample. Weight of all samples was measured at 24, 48, 72, 96, and 120 hours with subsequently changing each solution at an interval of 24 hours.

RESULTS

The mean pH of the beverages was found ranging from 2.13 ± 0.02 in Pepsi to 3.41 ± 0.02 in Tropicana on opening. The mean pH of water was found to be 6.98 ± 0.01. Among carbonated drinks, the mean weight loss after 24 hours was highest in Coca-Cola and least in 7Up. Tropicana fruit juice had a higher tooth loss than real orange juices. When compared with water, the tooth loss was significantly higher in Coca-Cola after all specified time (hours).

CONCLUSION

The pH of both carbonated drinks and fruit juices was below the critical pH. The weight loss was also seen after every 24 hours in all the carbonated drinks and beverages. The study showed that these commercial beverages are harmful to the tooth structures, and hence, the health professionals play a major role in educating the population about its effects and advising them to use these products precisely.

CLINICAL SIGNIFICANCE

The change in lifestyle has increased the demand of soft drinks and artificial juice in Indian market. The use of these carbonated drinks and fruit juices causes damage to the tooth structure in all ages, especially in young mass. Our study provides an idea about the deleterious effects of these commercial drinks on dental hard tissues.

Dental and oropharyngeal lesions in rats with chronic acid reflux esophagitis

OBJECTIVE

In this study, we evaluated pathological changes in the tooth and pharynx of GERD rats to elucidate the association between gastric acid reflux and oral and pharyngeal diseases.

METHODS

An experimental rat model of chronic acid reflux esophagitis was surgically created. The oral cavities were observed histologically every 2 weeks until 20 weeks after surgery.

RESULTS

At 10 weeks after surgery, molar crown heights in GERD rats were shorter than that in control rats, and inflammatory cell infiltration by gastric acid reflux was found in the periodontal mucosa of GERD rats. Furthermore, dental erosion progressed in GERD rats at 20 weeks after surgery, and enamel erosion and dentin exposure were observed. During the same period, inflammatory cell infiltration was observed in the mucosa of the posterior part of the tongue. These findings suggest that gastric acid reflux may be one of the exacerbating factors of dental erosion, periodontitis and glossitis.

CONCLUSION

We investigated oral changes in an experimental rat model of GERD and observed development of dental erosion, periodontitis and glossitis. Our findings suggested chronic gastric acid reflux may be involved in the pathogenesis of oral disease.

Are grape juices more erosive than orange juices?

AIMS

To evaluate the chemical characteristics of grape and orange juices, and their erosive potential in the decrease of microhardness and the loss of enamel structure.

METHODS

Five grape and orange juices were evaluated for pH, titratable acidity, calcium, phosphate, and fluoride concentration. De-ionised water and Cola soft drink were used as a negative and positive control, respectively. Twelve specimens of bovine enamel were immersed in beverages for 10 min at 37 °C, 3 times/day for 7 days. Erosive potential was quantified using microhardness and loss of enamel structure. Anova One Way, Student's t test, Multiple Regression and Spearman Correlation (p < 0.05) were used to analyse the results.

RESULTS

Powdered grape juice showed the lowest pH (3.18 ± 0.03) and pure grape juice presented the highest titratable acidity (5.48 ± 0.06 mL NaOH/100 mL). Fresh orange juice and soya-based grape juice revealed the lowest calcium (0.77 ± 0.12 mmol/L) and phosphate concentrations (0.35 ± 0.06 mmol/L), respectively. Among juices, powdered orange juice caused the greatest decrease in surface microhardness (SMH) (127.99 ± 40.47 ΔSMH) and grape juice from concentrate caused the greatest loss of enamel structure (13.30 ± 3.56 μm).

CONCLUSIONS

All of the evaluated juices contributed to dental erosion. Grape juices presented greater erosive potential than orange juices. Pure, powdered and concentrated grape juices showed similar loss of enamel structure to the Cola soft drink. The erosive potential of beverages was statistically correlated to pH, titratable acidity, calcium, phosphate and fluoride concentrations.

In vitro evaluation of modified surface microhardness measurement, focus variation 3D microscopy and contact stylus profilometry to assess enamel surface loss after erosive-abrasive challenges

The aim of the study was to compare surface loss values after erosion-abrasion cycles obtained with modified surface microhardness measurement (mSMH), focus variation 3D microscopy (FVM) and contact stylus profilometry (CSP). We cut human molars into buccal and lingual halves, embedded them in resin and ground 200 μm of enamel away. The resulting surfaces were polished. To maintain a reference area, we applied Block-Out resin to partly cover the enamel surface. The samples were incubated in artificial saliva (37°C; 1 h), then rinsed in deionized water (10 s) and dried with oil-free air (5 s). We immersed the specimens individually in 30 mL citric acid (1%, pH 3.6) for 2 min (25°C, 70 rpm dynamic conditions) before brushing them (50 strokes, 200 g) in an automatic brushing machine with toothpaste-slurry. We calculated the surface loss as per mSMH, by re-measuring the length of the same six indentations made before the abrasive challenge. The experiment consisted of five experimental groups that received between 2 and 10 erosion-abrasion cycles. Each group contained 15 specimens and samples in groups 1, 2, 3, 4 and 5 underwent a total of 2, 4, 6, 8 and 10 cycles, respectively. The resin was removed from the reference area in one piece under 10× magnification and the FVM and CSP were performed. Agreement between the methods was calculated with the intraclass correlation coefficient (ICC) and depicted in Bland-Altman plots. All methods presented a linear pattern of surface loss measurements throughout the experiment, leading overall to a strong, statistically significant correlation between the methods (ICC = 0.85; p<0.001). So, despite the different surface loss values, all methods presented consistent results for surface loss measurement.

Erosive effects of pediatric liquid medicinal syrups on primary enamel: An in vitro comparative study

Context:

The use of liquid medicinal syrups in childhood is high owing to the reasons that children suffer from illness quite often. The acidic component in the formulations may cause erosion to the dental tissues.

Aims:

The aim of this study is to evaluate the erosive potential of pediatric liquid medicinal syrups on the deciduous teeth.

Subjects and Methods:

A total of sixty extracted/exfoliated noncarious deciduous molars were used. Four medical syrups were used (viz., 1 – artificial saliva [control], 2 – Ferium XT, 3 – Crocin syrup, 4 – Ambrolite-D) and the teeth were equally divided into the four groups (n = 15) for the immersion cycle, following which the teeth were examined for surface microhardness at 7, 14, 21, and 28 days.

Statistical Analysis Used:

ANOVA and post hoc analysis were applied.

Results:

The time and immersion media interaction demonstrated that antitussives produced a significant and gradual loss of surface microhardness on all days (viz., 7, 14, 21, and 28 days), but a statistically significant difference was seen only between 7^th and 28^th day (P < 0.05).

Conclusions:

The knowledge of the erosive potential of commonly used syrups is mandatory as erosion in children teeth may be associated with dental hypersensitivity, loss of the occlusal vertical dimension, eating difficulties, poor esthetics, pulp exposure, and abscesses. Mouth rinsing with water after taking the medication; addition of calcium, fluoride, or phosphate to formulations; and consumption of the medication at meal times have been recommended to avoid tooth damage that is caused by the regular use of medication.

Nano-hydroxyapatite could Compensate the Adverse Effect of soft carbonated Drinks on Enamel

INTRODUCTION

Since one of the most important disadvantages of soft drinks includes their adverse effect on mineral content of enamel because of their low pH, this study examined the microhardness of enamel before and after exposure to a soft drink containing different concentrations of nano-hydroxyapatite (nano-HA) as an additive.

MATERIALS AND METHODS

Sixty caries free human premolars were mounted in epoxy resin. After polishing, the baseline micro-hardness was recorded three times for each specimen using a Vickers indenter at 50 gm load. Subsequently, the samples were divided into six groups, which were treated for 5 minutes at 9°C by a cola-based drink contacting 0, 0.5, 1, 5, and 10 wt.% of nano-HA while the control group was immersed in artificial saliva. Ultimately, the final microhardness was assessed three times again for each specimen.

RESULTS

Paired t-test showed that in groups containing 0 and 0.5 wt.% of nano-HA, the microhardness was significantly reduced after treatment protocol (p = 0.00 and 0.01 respectively). Whereas in the other groups the microhardness was not significantly changed after treatment (p > 0.05).

CONCLUSION

Pure cola-based drink has a pronounced adverse effect on enamel microhardness, while admixing it with nano-HA could act as a protective factor.

CLINICAL SIGNIFICANCE

Although soft beverages are hazardous to tooth structure, some additives could compensate their adverse effect.

Efficacy of amelogenin-chitosan hydrogel in biomimetic repair of human enamel in pH-cycling systems

Amelogenin-chitosan (CS-AMEL) hydrogel has shown great potential for the prevention, restoration, and treatment of defective enamel. As a step prior to clinical trials, this study aimed to examine the efficacy of CS-AMEL hydrogel in biomimetic repair of human enamel with erosive or caries-like lesions in pH-cycling systems. Two models for enamel defects, erosion and early caries, were addressed in this study. Two pH-cycling systems were designed to simulate the daily cariogenic challenge as well as the nocturnal pH conditions in the oral cavity. After pH cycling and treatment with CS-AMEL hydrogel, a synthetic layer composed of oriented apatite crystals was formed on the eroded enamel surface. CS-AMEL repaired the artificial incipient caries by re-growing oriented crystals and reducing the depth of the lesions by up to 70% in the pH-cycling systems. The results clearly demonstrate that the CS-AMEL hydrogel is effective at the restoration of erosive and carious lesions under pH-cycling conditions.

Analyses of the Erosive Effect of Dietary Substances and Medications on Deciduous Teeth

This study aimed at analysing the erosive potential of 30 substances (drinks, candies, and medicaments) on deciduous enamel, and analyse the associated chemical factors with enamel dissolution. We analysed the initial pH, titratable acidity (TA) to pH 5.5, calcium (Ca), inorganic phosphate (P_i), and fluoride (F) concentration, and degree of saturation ((pK -pI)_HAP, (pK -pI)_FAP, and (pK−pI)_CaF2) of all substances. Then, we randomly distributed 300 specimens of human deciduous enamel into 30 groups (n = 10 for each of the substances tested. We also prepared 20 specimens of permanent enamel for the sake of comparison between the two types of teeth, and we tested them in mineral water and Coca-Cola^®. In all specimens, we measured surface hardness (VHN: Vickers hardness numbers) and surface reflection intensity (SRI) at baseline (SH_baseline and SRI_baseline), after a total of 2 min (SH_2min) and after 4 min (SH_4min and SRI_4min) erosive challenges (60 ml of substance for 6 enamel samples; 30°C, under constant agitation at 95 rpm). There was no significant difference in SH_baseline between deciduous and permanent enamel. Comparing both teeth, we observed that after the first erosive challenge with Coca-Cola^®, a significantly greater hardness loss was seen in deciduous (−90.2±11.3 VHN) than in permanent enamel (−44.3±12.2 VHN; p = 0.007), but no differences between the two types of teeth were observed after two challenges (SH_4min). After both erosive challenges, all substances except for mineral water caused a significant loss in relative surface reflectivity intensity, and most substances caused a significant loss in surface hardness. Multiple regression analyses showed that pH, TA and Ca concentration play a significant role in initial erosion of deciduous enamel. We conclude that drinks, foodstuffs and medications commonly consumed by children can cause erosion of deciduous teeth and erosion is mainly associated with pH, titratable acidity and calcium concentration in the solution.

Amazonian delicacy tucupi is as erosive as a cola-based soft drink

OBJECTIVE

Acidic diets are advocated as main risk factor for tooth erosion, which could be prevented, or at least controlled, if patients were early advised. It is important to identify, hence, if possible dietary constituents regionally consumed on large scale, such as tucupi, a low-pH yellowish-green color and strong flavor delicacy made from the juice of a bitter cassava, may explain its occurrence in specific patient groups. This cross-over in situ/ex vivo study evaluated tucupi's ability to promote erosion of bovine enamel by assessing its percentage of surface microhardness change (%SMHC), taking a cola-based soft drink and human saliva as positive and negative controls.

DESIGN

For three 7-days spaced out legs of 7 days each, nine volunteers wore palatal devices with three bovine enamel blocks, which were challenged with one of the following solutions: TUC-tucupi (n=27); COL-cola-based soft drink (n=27); SAL-saliva (n=27). Erosive challenges were performed extra-orally (4×/day) by dropping TUC or COL at room temperature on specimens. After 5min, palatal devices were replaced into the mouth. SAL permanently acted as the negative control while volunteers solely wore the device. One-way ANOVA followed by Tukey's post-hoc tests (α=0.05) were applied.

RESULTS

TUC promoted an enamel %SMHC (-21.56±10.08(a)) similar than that promoted by COL (-18.19±12.99(a); p=0.275), which were both significantly higher than that promoted by SAL (-1.86±13.65(b); p<0.0001).

CONCLUSIONS

Besides the most worldwide appreciated cola-based soft drink, the greatly consumed Amazonian delicacy tucupi can be considered a potential risk factor for tooth erosion.

Água de coco em pó como suplemento hidroeletrolítico e energético para atletas

RESUMO Introdução: O uso de bebidas esportivas vem sendo adotado em diversas modalidades com o intuito de propiciar hidratação adequada durante atividades físicas. A água do coco verde vem sendo usada como repositor de eletrólitos devido à sua composição físico-química rica em sais minerais. Objetivo: Avaliar uma bebida esportiva à base de água de coco em pó (ACP ) a partir de um blend de ACP com polpa de maracujá (Passiflora edulis S.) voltada ao mercado de alimentos funcionais, com o objetivo de melhorar o desempenho de atletas amadores e profissionais em relação a um produto repositor eletrolítico já estabelecido no mercado (Gatorade sabor maracujá). Métodos: O experimento obedeceu a um delineamento inteiramente casualizado em esquema fatorial 2 x 2 x 3 (2 gêneros x 2 tipos de bebidas x 3 dias da semana), comparando o desempe-nho de dois grupos de atletas, sendo cinco atletas do sexo masculino e cinco atletas do sexo feminino, em relação à eficácia de dois suplementos hidroeletrolíticos (ACP com 20% de polpa de maracujá e Gatorade sabor maracujá) em diferentes dias da semana (segunda-feira, quarta-feira e sexta-feira). Resultados: ACP com polpa de maracujá apresentou resultados semelhantes ao Gatorade sabor maracujá em relação à os-molaridade plasmática do sangue dos atletas, os quais não apresentaram nenhuma perda de desempenho e tiveram maior conforto gástrico ao se hidratarem com ACP com polpa de maracujá. Conclusão: As respostas fisiológicas mostram a eficiência de ACP com polpa de maracujá como um repositor de eletrólitos seme-lhante ao do produto Gatorade sabor maracujá, podendo assim ACP com polpa de maracujá também ser utilizada como uma bebida esportiva.

Effect of acidity upon attrition-corrosion of human dental enamel

Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear.

Wear of two pit and fissure sealants in contact with primary teeth

Objectives:

Wear simulations may provide an indication of the clinical performance of pit-and-fissure sealants when associated with primary teeth as counterbody, restricting the involved variables. The aim of this study was to evaluate wear of dental materials used as pit-and-fissure sealants in contact with primary teeth.

Materials and Methods:

A resinous sealant (Fluroshield^®) and a resin-modified glass ionomer cement (Vitremer^®) were selected in a post-plate design, using as counterbody primary tooth pins (4 × 4 × 2 mm) at 3 and 10 N vertical load, 1 Hz frequency, 900 wear cycles in artificial saliva (n = 15). Attrition coefficient values were obtained and the material and primary tooth volumes were analyzed. Data were analyzed statistically by ANOVA and Duncan's test (P < 0.05).

Results:

Fluroshield^® presented the highest attrition coefficient values for the 3 N but these values decreased significantly for the 10 N load. The means for volume loss (3 mm) of the different samples after the wear test were not statistically different for the materials. The volume loss values for the primary teeth were statistically different and there was an increase in volume loss with the increase of the load applied in the wear tests.

Conclusions:

Differences were also observed with regard to the surface deformation characteristics. The wear rates of primary tooth enamel vary according to the type of material and the load applied during mastication.

The effects of smoothies on enamel erosion: an in situ study

OBJECTIVES

To measure, in vitro, the pH and titratable acidity (TA) of various soft drinks and to assess the erosive effect of smoothies using an in situ model.

METHOD

The in vitro phase of this study included measuring the inherent pH of six different commercially available smoothies, diet coke, and citric acid 0.3% (positive control) using a pH meter. The TA was determined by titration with NaOH. In the second part of the study, an in situ model was used. An upper removable appliance capable of retaining two enamel slabs was constructed and worn by 14 volunteers. The drinks under test were Innocent(®) strawberries and banana smoothie and citric acid. Volunteers were instructed to dip the appliance in the test solutions extra-orally five times daily for 2 min each time for 21 days. Measurements of enamel loss were made by surface profilometry and microhardness.

RESULTS

Diet Coke was found to be the most acidic drink (pH 2.61), whereas Innocent(®) mangoes and passion fruit smoothie showed to be the least (pH 3.9). With regard to TA, Innocent(®) blackberries, strawberries, and blackcurrant smoothie had the highest TA requiring 10.8 mol of NaOH to reach pH 7.0, whereas citric acid required only 3.1 mol of NaOH to reach the same pH value. Surface profilometry and microhardness testing revealed that citric acid caused a statistically significantly greater tooth surface loss compared with smoothie after 21-day pH cycling protocol.

CONCLUSION

Smoothies are acidic and have high TA levels. Innocent(®) strawberries and banana smoothie had an erosive potential to the teeth. However, its erosive effect was significantly less compared with citric acid after 21-day pH cycling protocol using an in situ model.

In Vitro Erosive Effect of Pediatric Medicines on Deciduous Tooth Enamel

This study evaluated, in vitro, the erosive potential of pediatric liquid medicines in primary tooth enamel, depending on the exposure time. Sixty deciduous incisors were randomly assigned to 4 groups (n=15), according to the immersion solutions: guaifenesin; ferrous sulfate; salbutamol sulfate and artificial saliva. The immersion cycles in the medicines were undertaken under a 1-min agitation, which wasperformed three times daily, during 28 days. Surface microhardness was measured at 7,14, 21 and 28 days. The titratable acidity and buffering capacity of the immersion media were determined. Data were analyzed by Analysis of Variance and Tukey's test (α=0.05). Salbutamol sulfate caused a gradual loss in enamel microhardness deciduous, observed at all times (p<0.005). Exposure to guaifenesin or ferrous sulfate resulted in significant decrease of enamel microhardness only after 28 days (p<0.005). In the control group (artificial saliva), microhardness did not changed (p>0.005) at any of the studied times. Scanning Electron Microscopy (SEM) images revealed that after 28 days the surfaces clearly exhibited structural loss, which was unlike those immersed in artificial saliva. Erosion of deciduous enamel was dependent on the type of medicine and exposure time.

Supplementation of soft drinks with metallic ions reduces dissolution of bovine enamel

OBJECTIVE

The aim of this study was to evaluate the effect of the addition of metallic ions to carbonated drinks on their erosive potential.

MATERIAL AND METHODS

Powdered enamel was added to carbonated beverages (Coca-ColaTM or Sprite ZeroTM and shaken for 30 s. The samples were then immediately centrifuged and the supernatant removed. This procedure was repeated 5 times with the beverages containing Cu2+, Mg2+, Mn2+ or Zn2+ (1.25-60 mmol/L). For Coca-ColaTM, the concentration of each ion that exhibited the highest protection was also evaluated in combination with Fe2+. The phosphate or calcium released were analyzed spectrophotometrically. Data were analyzed using ANOVA and Tukey's test (p<0.05).

RESULTS

For Coca-ColaTM, the best protective effect was observed for Zn2+ alone (10 mmol/L) or in combination (1 mmol/L) with other ions (12% and 27%, respectively, when compared with the control). Regarding Sprite ZeroTM, the best protective effect was observed for Cu2+ at 15 and 30 mmol/L, which decreased the dissolution by 22-23%. Zn2+ at 2.5 mmol/L also reduced the dissolution of powdered enamel by 8%.

CONCLUSIONS

The results suggest that the combination of metallic ions can be an alternative to reduce the erosive potential of Coca-ColaTM. Regarding Sprite ZeroTM, the addition of Cu2+ seems to be the best alternative.

Remineralization of eroded enamel lesions by simulated saliva in vitro

Purpose:

The purpose of this study was to evaluate the effects of two simulated saliva (SS) remineralization solutions comprising different calcium-inorganic phosphate (Ca/P_i) ratios on eroded enamel.

Methods:

3 mm diameter enamel cores were extracted from bovine teeth, mounted in acrylic rods, ground and polished,and initially demineralized with either 0.3% (120 minutes) or 1.0% (30 minutes) citric acid solutions (pH 3.8). Both sets of initially eroded specimens were evaluated for surface microhardness (N=10) and treated with either 0.3 or 1.6 Ca/P_i ratio SS. Groups were first exposed to a seven-day remineralization period and then were cycled in a three-day regimen consisting daily of three rounds of two-hour plus overnight SS treatments and three 10-minute static immersions in demineralization solution. Specimens were assessed using surface microhardness and scanning electron microscopy.

Results:

Initial erosion from 0.3% citric acid led to elliptical-shaped pore openings several microns in length and in depth and contrasted significantly with respect to 1% citric acid. The greatest remineralization was observed from the 0.3 Ca/P_i SS, while the 1.6 Ca/P_i SS produced the least.

Conclusions:

This study demonstrated the nature of remineralization of eroded enamel depends on both initial erosive conditions and the Ca/P_i ratio of simulated saliva.

Estimated erosive potential depends on exposure time

OBJECTIVES

Evaluate erosive potential of beverages, using exposure times from 3 to 30 min, and to analyse the relationship between erosion and several drink parameters.

METHODS

pH, calcium, phosphate and fluoride concentration, saturation, titratable-acidity to pH 5.5 and the viscosity of sixteen beverages were measured or calculated. Enamel samples (N = 90) were serially exposed to 1 ml of the beverages for 3, 6, 9, 15 and 30 min and erosion was measured as the loss of calcium to the beverage. Rate of erosion per min was calculated by linear curve fitting using all exposure times. Linear regression analysis was performed to determine the correlation between erosion and the drink parameters. A limited multivariate analysis was performed for the outcome parameter with the highest univariate correlations (erosion per minute) and 4 drink variables.

RESULTS

A negative relationship was observed only for pH for all exposure times. Only for erosion per min a significant relationship with pH and saturation was found. In a model for erosion per min using only saturation, fluoride concentration, titratable acidity and viscosity, both saturation and viscosity were shown to have a significant effect (p = 0.01 and p = 0.05, respectively).

CONCLUSION

Exposure times between 3 and 30 min result in very different estimates of erosive potential. There is no sound theoretical ground for preferring one or other exposure time/outcome as being more clinically relevant.

CLINICAL RELEVANCE

This study shows that effect of the choice of study methodology on the measurement of erosive potential of beverages is large.

Microhardness change of enamel due to bleaching with in-office bleaching gels of different acidity

OBJECTIVE

The aim of this study was to assess the enamel microhardness treated with three in-office bleaching agents, containing 35% hydrogen peroxide with different acidity.

MATERIALS AND METHODS

Bovine incisors were divided into three groups that received the following bleaching agents: Whiteness HP, Total Bleach and Opalescence Xtra. Three gel applications/10-min each, totaling 30-min of bleaching treatment, were made on the teeth and activated with a blue LED (1000 mW/470 nm) combined to a LASER (120 mW/795 nm) device (Easy Bleach-Clean Line). Vickers hardness (VH) was evaluated at baseline and after the bleaching procedure. The values of Hardness loss [HNL] (% reduction) were calculated. The two-sample t-test was used for comparison of the HNL of the three bleaching products (5% level of significance).

RESULTS

The Opalescence Xtra, which had the lowest pH value (pH = 4.30), showed a significant increase of HNL when compared with Total Bleach bleaching agent, which had the highest pH value (pH = 6.62).

CONCLUSIONS

The 35% hydrogen peroxide bleaching agents resulted in a reduction in surface enamel microhardness and bleaching with the most acid agent resulted in a significant enamel hardness loss compared to the less acid agent (4.30 vs 6.62). Strategies proposed to reduce the enamel loss after bleaching treatment may include the use of daily fluoride therapy, mouth rinsing (fluoride, milk and sodium bicarbonate solution), fluoride/bicarbonate dentifrices without abrasives, do not toothbrush immediately after bleaching, fluorides and calcium add to bleaching agents.

Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release

We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r(2) ≥ -0.86) as well as calcium release (r(2) ≥ -0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r(2) = 0.42-0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo.

Analysis of the erosive effect of different dietary substances and medications

Excessive consumption of acidic drinks and foods contributes to tooth erosion. The aims of the present in vitro study were twofold: (1) to assess the erosive potential of different dietary substances and medications; (2) to determine the chemical properties with an impact on the erosive potential. We selected sixty agents: soft drinks, an energy drink, sports drinks, alcoholic drinks, juice, fruit, mineral water, yogurt, tea, coffee, salad dressing and medications. The erosive potential of the tested agents was quantified as the changes in surface hardness (ΔSH) of enamel specimens within the first 2 min (ΔSH2-0 = SH2 min - SHbaseline) and the second 2 min exposure (ΔSH4-2 = SH4 min - SH2 min). To characterise these agents, various chemical properties, e.g. pH, concentrations of Ca, Pi and F, titratable acidity to pH 7·0 and buffering capacity at the original pH value (β), as well as degree of saturation (pK - pI) with respect to hydroxyapatite (HAP) and fluorapatite (FAP), were determined. Erosive challenge caused a statistically significant reduction in SH for all agents except for coffee, some medications and alcoholic drinks, and non-flavoured mineral waters, teas and yogurts (P < 0·01). By multiple linear regression analysis, 52 % of the variation in ΔSH after 2 min and 61 % after 4 min immersion were explained by pH, β and concentrations of F and Ca (P < 0·05). pH was the variable with the highest impact in multiple regression and bivariate correlation analyses. Furthermore, a high bivariate correlation was also obtained between (pK - pI)HAP, (pK - pI)FAP and ΔSH.

In vitro alterations in dental enamel exposed to acidic medicines

OBJECTIVE

To evaluate the effect of acidic medicines (Klaricid(®), Claritin(®), and Dimetapp(®)) on surface enamel in vitro.

METHODS

Enamel blocks (n=104) were randomly distributed into two groups: G1 (pH-cycling simulating physiological oral conditions) and G2 (erosive conditions). Each group was divided into four subgroups, three to be immersed in the medicines and the control in deionized water. Specimen surfaces were evaluated for roughness and hardness at baseline and again after the in vitro experimental phase, which included 30 min immersions in the medicines twice daily for 12 days. Scanning electron microscopy (SEM) was also performed after the in vitro experimental phase.

RESULTS

All medicines produced a significant reduction in hardness in G1 after 12 days (P<0.05). The three medicines promoted greater roughness after both pH-regimens - G1 and G2 (P<0.01), except for Claritin in G1. Scanning electron microscopy analysis showed erosive patterns in all subgroups. Dimetapp(®) showed the most erosion and Klaricid(®) the least, in both groups.

CONCLUSION

Dimetapp(®) (lowest pH and viscosity) and deionized water (control) showed the most pronounced erosive patterns. Klaricid(®) (highest pH and viscosity) presented an in vitro protective effect against acid attacks perhaps due to its mineral content and viscosity.

Development of an orange juice surrogate for the study of dental erosion

The aim of this study was to create a synthetic juice (SJ) to be used as a surrogate for natural orange juices in erosion studies, verifying its erosive potential. The SJ was formulated based on the chemical composition of orange juices from different locations. Forty enamel and 40 root dentin specimens were randomly assigned into 4 experimental groups (n=10): SJ; 1% Citric Acid (CA); Minute Maid Original® (MM) and Florida Natural Original® (FN). The specimens were immersed in their respective solutions for 5 min, 6x/day for 5 days, in an erosion-remineralization cycling model. Enamel specimens were analyzed by surface Knoop microhardness and optical profilometry and dentin specimens only by optical profilometry. Outcomes were analyzed statistically by ANOVA followed by Tukey’s test considering a significance level of 5%. For enamel, the surface loss and microhardness changes found for MM and SJ groups were similar (p>0.05) and significantly lower (p<0.01) than those found in the CA group. For dentin, CA promoted significantly greater (p<0.01) surface loss compared with all the other groups. No significant difference (p>0.05) was observed in dentin surface loss between MM and SJ. In conclusion, CA was the most erosive solution, and SJ had a similar erosive potential to that of MM natural orange juice.