Effect of Salivary Stimulation on Erosion of Human and Bovine Enamel Subjected or Not to Subsequent Abrasion: An in situ/ex vivo Study

Should We Wait to Brush Our Teeth? A Scoping Review Regarding Dental Caries and Erosive Tooth Wear

BACKGROUND

Tooth brushing is a universal recommendation. However, the recommendations related to the time of its execution are conflicting, especially when dealing with patients at risk of erosive tooth wear (ETW) or dental caries.

SUMMARY

Our objective was to summarize the evidence on the timing of brushing with fluoridated toothpaste in relation to ETW and cariogenic dietary challenges. We conducted a scoping review following the PRISMA-ScR checklist, using three databases searching for in vivo, in situ, or in vitro studies involving human teeth exposed to either a cariogenic or an erosive challenge. Only models including human saliva and fluoride were assessed. Data selection, extraction, and risk of bias analysis were done in duplicate and independently. From 1,545 identified studies, 17 (16 related to ETW and 1 to dental caries) were included. Most evidence (n = 10) supported that brushing with a fluoride-containing product does not increase ETW, independent of the moment of brushing. Delaying tooth brushing up to 1 h (n = 4) or individualized recommendations based on the patient's problem (n = 2) were less frequent. Only one study reported that brushing pre- or post-meal does not affect Streptococcus mutans counts. Most data were in situ (n = 13), and the overall study quality was judged as sufficient/low risk of bias.

KEY MESSAGES

Although the available evidence lacked robust clinical studies, tooth brushing using fluoridated products immediately after an erosive challenge does not increase the risk of ETW and can be recommended, which is in line with recommendations for dental caries prevention. Furthermore, we suggest updating the international guidelines to promote individualized recommendations based on risk factors to prevent either ETW or dental caries.

The Effect of Oral Care Foams and a Spray on Salivary pH Changes after Exposure to Acidic Beverages in Young Adults

Soft drinks may have a deleterious effect on dental health due to a high titratable acidity and a low pH that could be sufficient to induce tooth demineralization. The use of oral care products immediately after acidic challenge may diminish the erosive potential of soft drinks. We assessed the effect of oral care foams and a spray on salivary pH changes after exposure to Coca-Cola® in young adults. Thirty-three consenting eligible patients were recruited in this double-blind, randomized, crossover study performed in six visits. Baseline examination included unstimulated salivary flow rate, stimulated salivary buffer capacity, and the simplified oral hygiene index (OHI-S) assessment. Salivary pH and time for pH recovery were registered after exposure to Coca-Cola® alone or that followed by the application of each of the studied products (an oral foam containing hydroxyapatite and probiotics, an oral foam containing amino fluoride, an alkaline oral spray, and tap water). Thirty-two patients completed the entire study protocol and were included in the final analysis. The mean minimum salivary pH and the mean oral clearance rate after rinsing with Coca-Cola® were 6.3 and 27 min, respectively. Further rinsing with any one of the tested solutions, including tap water, resulted in a significant improvement in these parameters. When the pH curves were plotted, the oral care products demonstrated a lower area under the curve that differed significantly from the area under the curve for Coca-Cola®; tap water did not differ significantly from Coca-Cola® and oral care products. Minimum salivary pH correlated positively with salivary buffer capacity and salivation rate, while salivary clearance correlated with OHI-S plaque scores. In conclusion, the effect of oral care foams and a spray on minimum salivary pH and salivary clearance after exposure to Coca-Cola® did not differ significantly among the tested products and tap water. Trial registration NCT06148662. Funding: none.

Polarization-Sensitive Optical Coherence Tomography for Monitoring De- and Remineralization of Bovine Enamel In Vitro

Early caries diagnosis still challenges dentistry. Polarization-sensitive optical coherence tomography (PS-OCT) is promising to detect initial lesions non-invasively in depth-resolved cross-sectional visualization. PS-OCT with determined degree of polarization (DOP) imaging provides an intuitive demineralization contrast. The aim of this study is to evaluate the suitability of DOP-based PS-OCT imaging to monitor controlled de- and remineralization progression for the first time and to introduce it as a valid, non-destructive in vitro detection method. Twelve standardized bovine enamel specimens were divided in different groups and demineralized with hydrochloric acid (HCl) as well as partly remineralized with fluoride over a 14-day pH-cycling experiment. The specimens were stored in artificial saliva and sodium chloride (NaCl), respectively. Progress measurements with PS-OCT were made with polarization-sensitive en faceand B-scan mode for qualitative evaluation. The specimens demineralized in HCl showed the most pronounced surface change (lowest DOP) and the most significant increase in depolarization. Additional fluoride treatment and the storage in artificial saliva resulted in the opposite (highest DOP). Therefore, DOP-based PS-OCT imaging appears to be a valuable technique for visualization and monitoring of enamel demineralization and remineralization processes in vitro. However, these findings need to be confirmed in human teeth ex vivo or in situ.

Effect of high-fluoride dentifrice on root dentine de-remineralization exposed to erosion challenge in vitro

Background

High-fluoride dentifrice can be used to manage dental erosion; however, little is known about it effect on root dentine previously demineralized. This study evaluated the effect of high-fluoride treatment on dentin de/remineralization exposed to an erosion challenge in vitro.

Material and Methods

Sound and demineralized dentine blocks were submitted to a 5-days-erosive challenge in soft drink (4/day during 90 s) and treated with fluoride solutions (0, 1,100, or 5,000 µg F/mL). After this, the percentage of surface hardness loss (%SHL) or recovery (%SHR) was calculated. Data were analyzed by one-way ANOVA and Tukey post hoc test with p fixed at 5%.

Results

High-fluoride treatment was able to reduce dentine remineralization and increase mineral recovery of previously demineralized dentine compared to other treatments tested (p<0.05).

Conclusions

High-fluoride treatment was able to increase the remineralization and reduce the demineralization of root dentine submitted to an erosive challenge in vitro, being an option for the erosion prevention/treatment.

Key words:Fluorides, root caries, tooth erosion, toothpastes.

Diamond particles in toothpastes: in-vitro effect on the abrasive enamel wear

Background

Diamond particles have recently been used as abrasives in toothpastes, which raises questions about its abrasive behaviour towards enamel. This study was carried out to investigate the abrasive enamel wear caused by three diamond-loaded toothpastes (Candida White Diamond: CWD, Swiss Smile Diamond Glow: SSDG, Emoform F Diamond: EFD) and to compare it with a traditional toothpaste with silica abrasive (Colgate Total Original CTO).

Methods

Eighty bovine enamel samples were divided into four groups (n = 20) and brushed for 21,600 cycles (60 cycles/min) for 6 h at 2.5-N brushing force. The abrasive enamel wear was recorded with a contact profilometer. The median and interquartile range (IQR) of the abrasive enamel wear was calculated in each group. Pairwise comparisons were conducted using Wilcoxon signed rank exact test and the p value was adjusted according to Holm. Significance level was set at 0.05.

Results

Diamond-loaded toothpastes caused statistically significantly higher abrasive wear than the traditional toothpaste (p < 0.0001). SSDG caused statistically significantly higher enamel wear (19.0 µm (11.2)) than CWD (8.4 µm (4.6)) and EFD (7.3 µm (3.9)) (p < 0.0001).

Conclusions

Diamond-loaded toothpastes cause higher enamel wear than toothpastes with traditional abrasives and also exhibit different abrasivity behaviour compared to each other.

Protective effect of green tea catechins on eroded human dentin: an in vitro/in situ study

The present study sought to evaluate the protective effect of Epigallocatechin-3-gallate (EGCG) and commercial green tea (GT) on eroded dentin using in vitro and in situ experimental models. For the in vitro experiment, matrix metalloproteinases (MMPs) were extracted from demineralized human coronary dentin powder (citric acid, pH 2.3) and assessed via a colorimetric assay and electrophoresis in gelatin. The gels were exposed to buffers with: control (no treatment), 0.05% sodium fluoride (NaF), 0.12% chlorhexidine digluconate (CHX), GT infusion, and 0.1% EGCG, and their respective activity was analyzed by zymography. For the in situ experiment, 20 healthy volunteers (aged 20-32 years) participated in this single-center, blind, crossover study. The subjects wore upper removable devices containing four human dentin blocks. Erosive challenge (coke-1 min) was performed four times/day/5 days. Blocks were treated for 1 min with: control (No treatment), 0.05% NaF, 0.1% EGCG, and GT. Thereafter, the specimens were subjected to stylus profilometry and SEM. ANOVA was used to evaluate dentin roughness and wear, with a significance level of 5%. In the zymography analysis, 0.12% CHX, GT, and 0.1% EGCG were found to inhibit the action of MMPs; however, in the colorimetric assay, only green tea inhibited the activity of MMPs. There were no significant differences observed in dentin roughness or wear (p > 0.05). Herein, EGCG and GT inhibited the activity of endogenous proteases, resulting in protection against erosion-induced dentin damage; however, they could not prevent tooth tissue loss in situ.

Abrasion Behaviour of Different Charcoal Toothpastes When Using Electric Toothbrushes

OBJECTIVES

The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel.

MATERIALS AND METHODS

A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste-water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing.

RESULTS

The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets.

CONCLUSIONS

Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes.

CLINICAL RELEVANCE

As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

Effect of Cold Atmospheric Pressure Plasma Coupled with Resin-Containing and Xylitol-Containing Fluoride Varnishes on Enamel Erosion

Purpose

Considering the suggested advantages of cold atmospheric plasma (CAP) in increasing the fluoride uptake by the enamel, this study aimed to assess enamel erosion following the application of helium CAP and two types of fluoride varnishes.

Methods

The microhardness of 70 bovine enamel specimens was measured using a Vickers hardness tester. The specimens were randomly divided into 7 groups (n = 10): control, CAP (P), resin-containing fluoride varnish (RF), CAP + resin-containing fluoride varnish (PRF), fluoride varnish (F), CAP + fluoride varnish (PF), and erosion (E). The specimens in the control and erosion groups did not receive CAP or fluoride varnish. All specimens underwent erosive challenge 4 times/day using hydrochloric acid and artificial saliva except for the control specimens that remained in distilled water during the course of the study. After 5 days of erosive challenge, microhardness was measured again, and the percentage of microhardness change was calculated. Surface roughness of two specimens in each group was assessed by atomic force microscopy (AFM). Data were analyzed using one-way ANOVA followed by Tamhane's post-hoc test.

Results

The percentage of microhardness change in all groups was significantly higher than that of the control group. All groups showed significantly lower percentage of microhardness change compared with the E group except for the P group; no significant difference was noted in microhardness change of P and E groups. Other experimental groups had no significant difference with each other. Surface roughness was the highest in PRF and the lowest in the F group.

Conclusion

CAP application had no significant effect on increasing the enamel resistance to erosion. However, enamel resistance to erosion increased significantly after fluoride varnish application alone or fluoride varnish application combined with CAP. No significant difference was noted between the two types of varnishes in this regard. CAP increased the surface roughness while fluoride varnish application alone decreased the roughness.

Does delayed toothbrushing after the consumption of erosive foodstuffs or beverages decrease erosive tooth wear? A systematic review and meta-analysis

OBJECTIVE

Controversy exists regarding the effectiveness of delayed toothbrushing in decreasing erosive tooth wear (ETW). The purpose of this systematic review and meta-analysis was to assess the effects of delayed toothbrushing on ETW.

MATERIALS AND METHODS

This systematic review and meta-analysis was conducted according to the PRISMA statement and registered in PROSPERO (CRD42020200463). PubMed, Embase, and Web of Science databases were systematically searched with no publication year limits. Screening and data extraction were performed independently by two reviewers. In situ and in vitro studies comparing ETW after delayed and immediate toothbrushing following an erosive attack were included. Review Manager software 5.3 (The Cochrane Collaboration, Oxford, UK) was used for statistical analyses. Heterogeneity was assessed with the Cochran Q test and I² statistics.

RESULTS

Of the 565 potentially relevant studies, 26 full-text articles were assessed for eligibility. Twelve articles were included in the systematic review, and 11 were included in the qualitative analyses. No significant difference in the ETW of human enamel was observed between delayed and immediate toothbrushing (P = 0.13), whereas significantly less ETW of bovine enamel was observed after delayed toothbrushing (P < 0.001). No significant difference in the ETW of bovine dentin was observed between delayed and immediate toothbrushing (P = 0.34). Studies on human dentin were not available. Subgroup analyses revealed a significant contribution of the use of fluoridated toothpaste to decreasing the ETW of human enamel after erosion and toothbrush abrasion (P = 0.02).

CONCLUSIONS

Bovine and human teeth behaved differently in response to erosion and toothbrush abrasion. Delayed toothbrushing after an erosive attack was not effective at decreasing the ETW of human enamel compared to immediate toothbrushing, whereas it was effective at decreasing the ETW of bovine enamel.

CLINICAL RELEVANCE

Delayed toothbrushing alone after the consumption of erosive foodstuffs or beverages is not capable of preventing erosive enamel wear.

Dentifrices or gels containing MMP inhibitors prevent dentine loss: in situ studies

OBJECTIVES

Evaluate the effect of dentifrices or gels containing MMP inhibitors on dentine loss in situ.

MATERIALS AND METHODS

Acrylic palatal appliances containing bovine dentine blocks were divided into two rows, corresponding to the groups erosion (ERO) and erosion associated with abrasion (ERO+ABR). For ERO, the appliances were immersed in a cola drink for 5 min, 4 times/day, while for ERO+ABR, the blocks were brushed for 15 sec with a dentifrice slurry after the second and third erosive challenges. Ten volunteers took part in study 1 (S1), where the dentifrices evaluated contained 1100 ppm fluoride as NaF, 0.61% green tea extract, or 0.012% chlorhexidine digluconate. Thirteen volunteers participated in study 2 (S2), in which the treatment was performed only once (1 min) with gels containing 400 μM EGCG (EGCG400), 0.012% chlorhexidine, 1 mM FeSO₄, 1.23% F (NaF), placebo, or received no treatment. Dentine loss was analyzed by profilometry (μm).

RESULTS

Regarding S1, ERO+ABR induced significantly higher dentine loss compared with ERO and all dentifrices tested led to significantly lower dentine loss when compared with placebo. For S2, regardless of the conditions or times of evaluation, gels containing EGCG, CHX, or FeSO₄ led to significantly less wear compared with the other groups.

CONCLUSION

Both dentifrices and gels containing MMP inhibitors significantly reduced dentine loss.

CLINICAL RELEVANCE

Dentifrices and gels containing MMP inhibitors are able to increase the protection against dentine wear, although gels have a better effect when compared with fluoride gel, lasting up to 10 days after a single application.

Do commercial whitening dentifrices increase enamel erosive tooth wear?

Objective

This in vitro study evaluated the effect of commercial whitening dentifrices on erosive tooth wear (ETW) of bovine enamel samples, in comparison with commercial regular dentifrices.

Methodology

Sixty bovine crowns were embedded in acrylic resin, polished and then had their baseline profile determined. They were randomly assigned to 5 groups (n=12/group), according to the type of commercial dentifrice to be tested: GI – Crest Anti-cavity Regular; GII – Crest 3D White; GIII – Colgate Total 12 Clean Mint; GIV – Colgate Optic White; GV – Placebo (negative control, fluoride-free dentifrice). The samples were submitted to daily erosive and abrasive challenges for 3 days. The erosive challenges were performed 3 times a day by immersing the specimens in 0.1% citric acid solution (pH 2.5) for 90 s. Each day after the first and last erosive challenges, the specimens were subjected to the abrasive challenge for 15 s, using a toothbrushing machine (Biopdi, São Carlos, SP, Brazil), soft toothbrushes and slurry (1:3 g/ml) of the tested toothpastes (1.5 N). The specimens were kept in artificial saliva between the challenges. The final profile was obtained and the ETW (µm) was calculated. Data were analyzed by Kruskal-Wallis and Dunn’s tests (p<0.05).

Results

All dentifrices tested significantly reduced the enamel wear in comparison with the Placebo, except GIII. The median (95% CI) ETW was 1.35 (1.25-1.46)^bc for GI, 1.17 (1.01-1.34)^cd for GII, 1.36 (1.28-1.45)^ab for GIII, 1.08 (1.04-1.14)^d for GIV and 2.28 (2.18-2.39)^a for GV.

Conclusion

When dentifrices from the same manufacturer were compared, the whitening dentifrices led to similar or less wear than the regular ones.

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

BACKGROUND

The aim of this study was evaluated the eroded enamel rehardening potential using upper palatal and lower buccal removable appliances in different times of salivary exposure (30 min, 1h, 2h, 12h) after a single erosive challenge event.

MATERIAL AND METHODS

After initial surface hardness evaluation, bovine enamel blocks were eroded in vitro (0.01 M hydrochloric acid, pH 2.3, 30 seconds), selected (n = 160) and randomly assigned to the two appliance designs and twenty volunteers. Four enamel blocks were inserted in each removable appliance. On the in situ phase, the volunteers were instructed to use the upper palatal and lower buccal appliances simultaneously for 12 nonconsecutive hours. After each predetermined period of time of salivary exposure, the enamel blocks were removed from the appliances for immediate evaluation of surface hardness, enabling percentage of surface hardness recovery calculation (%SHR). The data were analyzed using two-way ANOVA and Tukey's test (α=5%).

RESULTS

The results showed no difference in the degree of enamel rehardening by the upper palatal or lower buccal appliances (p >0.0001). Regarding the time of use of the appliances, it was demonstrated that 30 minutes (upper = 21.12%, lower = 19.84%) and 1 hour (upper = 35.69%, lower = 30.50%) promoted lower hardness recovery than two hours (upper = 44.65%, lower 40.80%) of salivary exposure (p<0.0001). The use of 12 hours (upper = 49.33%, lower = 49.00%), including the sleeping time of the volunteers did not increase the %SHR.

CONCLUSIONS

The location of the appliance does not influence the re-hardening ability of saliva and the use of intraoral appliances for 2 hours seems to be appropriate for partial rehardening of the softened enamel surface. Key words:Tooth erosion, in situ, saliva, tooth remineralization.

Effect of 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.

Is the dentifrice containing calcium silicate, sodium phosphate, and fluoride able to protect enamel against chemical mechanical wear? An in situ/ex vivo study

OBJECTIVES

The aim of this study was to investigate the effect of a dentifrice that contains calcium silicate, sodium phosphate, and fluoride on erosive-abrasive enamel wear.

MATERIAL AND METHODS

This randomized, single-blind in situ/ex vivo study was conducted with four crossover phases of 5 days (one group tested per phase). Bovine enamel blocks (n = 256) were allocated to 16 volunteers and 8 groups. The groups under study were test dentifrice, with calcium silicate, sodium phosphate, and 1450 ppm sodium monofluorophosphate; tin dentifrice, with 3500 ppm stannous chloride, 700 ppm amine fluoride, and 700 ppm sodium fluoride; conventional dentifrice, with 1450 ppm sodium monofluorophosphate; and control (deionized water). Half of the enamel blocks were subjected to erosion and the other half to erosion plus abrasion. The daily extraoral protocol consisted in four citric acid exposures (2 min) and two applications of dentifrice slurry on all blocks for 30 s; after, half of the blocks were brushed for 15 s. The response variable was enamel loss. Data were analyzed by two-way ANOVA and Fisher's test (p < 0.05).

RESULTS

For erosion, the test dentifrice promoted less enamel loss than water (4.7 ± 3.1 and 5.8 ± 2.5 μm, respectively, p < 0.05), and did not differ from tin (4.8 ± 2.5 μm) and conventional (4.8 ± 1.4 μm) dentifrices (p > 0.05). However, the test dentifrice (7.7 ± 3.8 μm) promoted higher wear after erosive plus abrasive procedures than tin (5.4 ± 1.5 μm) and conventional (6.2 ± 1.7 μm, p < 0.05) dentifrices, and did not differ from water (6.9 ± 2.0 μm).

CONCLUSIONS

The investigated dentifrice reduced enamel loss against acid challenge but had no effect against acid and brushing challenge.

CLINICAL RELEVANCE

Little is known regarding the preventive effect of dentifrices indicated for dental erosion. The tested anti-erosive dentifrice was unable to protect enamel when erosion was associated to toothbrushing abrasion.

In situ effect of Tooth Mousse containing CPP-ACP on human enamel subjected to in vivo acid attacks

OBJECTIVE

This in situ study aimed to evaluate the protective effect of Tooth Mousse (GC) containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on human enamel erosion and to compare the difference in erosion between the anteriorly and posteriorly positioned human enamel.

METHODS

This study used a 2-treatment (7 days each) crossover design with 12 healthy volunteers wearing intraoral appliances. Each appliance contained 4 human enamel specimens positioned on the buccal surfaces of the volunteers' maxillary central incisors and first molars. The specimens were intraorally treated withTooth Mousse (CPP-ACP group) or deionized water (control group) for 3 min and then exposed to in vivo acid attacks by rinsing with 150 ml of a cola drink (4 × 5 min/day). The surface microhardness (SMH) of the specimens was measured and used to calculate the percentage of SMH loss (%SMH_l). Erosion effect on enamel was also investigated by scanning electron microscopy (n = 4) at the end of study. The data were statistically analysed using two-way analysis of variance (ANOVA) and Tukey's test at a level of P < 0.05.

RESULTS

A significant decrease in %SMH_l was observed for the specimens of CPP-ACP group compared to that for the controls (P = 0.007). The specimens positioned posteriorly exhibited a significantly lower %SMH_l than those positioned anteriorly (P = 0.033). Samples of CPP-ACP group showed fewer etching patterns than those of the control group.

CONCLUSIONS

In this in situ model, application of Tooth Mousse containing CPP-ACP before erosion reduced the %SMH_l of human enamel. Enamel located in different positions showed different patterns of erosion.

CLINICAL SIGNIFICANCE

Application of Tooth Mousse containing CPP-ACP could be considered as a suitable preventive strategy against enamel erosion. ClinicalTrials.gov Identifier: NCT03426150.

Non-contact profilometry of eroded and abraded enamel irradiated with an Er:YAG laser

Literature has reported positive results regarding the use of lasers in the control of erosive lesions; however, evaluating whether they are effective in the control of the progression of erosive/abrasive lesions is important.

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 presence of acquired enamel pellicle changes acid-induced erosion from dissolution to a softening process

Erosive wear undermines the structural properties of enamel resulting in irreversible enamel loss. A thin protein layer formed from natural saliva on tooth surfaces, acquired enamel pellicle (AEP), protects against erosive wear. The exact components in saliva responsible for such protection are not yet known. We prepared three solutions containing different components: proteins and ions [natural saliva (NS)], minerals with no proteins [artificial saliva (AS)] and neither proteins nor ions [deionised water (DW)]. To assess the protection of the three solutions against citric acid enamel erosion, enamel specimens were immersed in the corresponding solution for 24 h. All specimens were then exposed to five erosion cycles, each consisted of a further 30 min immersion in the same solution followed by 10-min erosion. Mean step height using a non-contacting profilometer, mean surface microhardness (SMH) using Knoop microhardness tester (final SMH), and roughness and 2D profiles using atomic force microscopy were measured after five cycles. The final SMH values were compared to the starting values (after 24 hr). NS group had significantly less tissue loss but greater SMH change (P < 0.0001) than AS and DW groups. Specimens in NS were softer and rougher (P < 0.001) but less eroded than specimens in AS and DW.

Effects of brushing timing after erosive challenge on enamel loss in situ: White light interferometer and nanoindentation study

This in situ study aimed to evaluate effects of waiting periods after erosive challenge before toothbrushing on enamel abrasion and nanoindentation hardness. Ten subjects wore intraoral appliances each with a set of 4 bovine enamel blocks. The enamel blocks were subjected to 2 cycles a day for 3 days as follows; intraoral exposure to form acquired pellicle and extraoral erosion followed by either 0, 3, 30 or 60 min intraoral exposure and then brushing, which was performed using an automatic brushing machine. Abrasive loss was assessed by white light interferometry. Nanoindentation was performed to calculate relative hardness. Abrasion and relative hardness were statistically analyzed by ANOVA. Abrasive loss was significantly less in groups exposed to saliva compared with 0 min (p<0.05); there was no significant difference between 30 and 60 min (p>0.05). Relative hardness was statistically higher after intraoral exposure, but no differences existed among any intraoral exposure periods (p>0.05).

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.

In situ effect of CPP-ACP chewing gum upon erosive enamel loss

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is able to increase salivary calcium and phosphate levels at an acidic pH. Previous studies demonstrated that a CPP-ACP chewing gum was able to enhance the re-hardening of erosion lesions, but could not diminish enamel hardness loss. Therefore, there is no consensus regarding the effectiveness of CPP-ACP on dental erosion.

Influence of Erosive and Abrasive Cycling on Bonding of Different Adhesive Systems to Enamel: An In situ Study

This study evaluated the impact of orange juice on the bond strength (BS) of dentin bonding systems (DBSs) to enamel surface after simulation with an in situ/ ex vivo erosive cycling. One hundred and ninety two bovine enamel fragments (4x4x2mm) were obtained and randomized regarding superficial microhardness and distributed to palatal devices for 8 volunteers, in three phases (one for each DBS), containing 8 blocks, which were, allocated in 4 pairs. Daily, these pairs were subjected extraorally to the following conditions: CONT- neither erosive nor abrasive challenge; ERO- erosive challenge only; ABR- abrasive challenge only and ERO + ABR- with erosive and abrasive challenges. Erosive cycles (immersion in orange juice, 3 times/day/5 min/5 days) or/and abrasive challenges (electric toothbrush, 3 times/day/1 min/5 days) were performed. After these cycles, all specimens were restored with the adhesive systems Adper Scotchbond Multi Purpose (MP), Adper Single Bond 2 (SB) or Clearfil SE Bond (SE), and the composite resin Filtek Z250. After 7 days, sticks (area ≅1 mm2) were obtained and subjected to the microtensile bond strength test (μTBS) at 0.5 mm/min. Data was statistically analyzed by ANOVA and Tukey tests (a=0.05). Failure modes were determined using a digital microscope (40´). DBS was the only statistical significant factor. SE was the unique DBS not affected in any challenge, whereas MP and SB performed according to the scenario. The adhesive and mixed failures were predominant in all groups. Overall performance suggested that BS to enamel after erosive /abrasive challenged by orange juice was not affected and it was material-dependent.

Remineralizing Potential of a Low Fluoride Toothpaste with Sodium Trimetaphosphate: An in situ Study

Objective: To evaluate the effect of a low-fluoride (F) toothpaste supplemented with sodium trimetaphosphate (TMP) on enamel remineralization in situ. Design: Bovine enamel blocks were selected on the basis of their surface hardness (SH) after caries-like lesions had been induced, and randomly divided into 4 treatment groups, according to the toothpastes used: without F or TMP (placebo); 500 ppm F; 500 ppm F plus 1% TMP; and 1,100 ppm F. The study design was blinded and crossover and performed in 4 phases of 3 days each. Eleven subjects used palatal appliances containing 4 bovine enamel blocks which were treated 3 times per day during 1 min each time, with natural slurries of saliva and toothpaste formed in the oral cavity during toothbrushing. After each phase, the percentages of surface (%SHR) and subsurface hardness recovery (%ΔKHNR) were calculated. F, calcium (Ca), and phosphorus (Pi) contents in enamel were also determined. Data were analyzed by 1-way, repeated-measures ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). Results: Toothpaste with 500 ppm F + TMP and 1,100 ppm F showed similar %SHR and %ΔKHNR as well as enamel F, Ca, and Pi concentrations. Conclusion: The addition of TMP to a low-fluoride toothpaste promoted a similar remineralizing capacity to that of a standard (1,100 ppm F) toothpaste in situ.

Are Pediatric Antibiotic Formulations Potentials Risk Factors for Dental Caries and Dental Erosion?

Introduction:

One of the most frequent parents’ concerns is that oral antibiotic formulations induce dental damage in their children’s. This study aimed to assess the cariogenic and erosive potentials of 29 pediatric antibiotics.

Materials and Methods:

Replicates of each antibiotic were analyzed for the concentration of sugars (sucrose, glucose and fructose) and sorbitol by high performance liquid chromatography (HPLC). The pH was determined by digital pHmeter. Titratable acidity was determined in triplicate using the same pHmeter by gradual addition of 0.1N sodium hydroxide (NaOH) until pH 7.0. Viscosity measurements were carried out using a viscosimeter. In order to rank the relative performance of each medicine, the DEA (Data Envelopment Analysis) methodology was used.

Results:

Sucrose was present in most samples (n=24) with concentrations ranging from 26 to ≈ 100g% (w/w). Only one antibiotic contained sorbitol (66.9g%). Twenty seven antibiotics presented pH values ranging from 4.1 to 6.9 and most of them (n=15) showed the pH below the critical value for dissolution of hydroxyapatite. The values of titratable acidity and viscosity ranged from 0.26 to 40.48 ml and from 20 to 1780cP, respectively. DEA methodology showed that two medicines were distant from the performance frontier (Klaricid^® 50mg and Zinnat^® 250mg), which means that these medicines showed the worst performance and, therefore, greater potential for dissolution of dental enamel.

Conclusion:

Many antibiotics presented high concentration of sugars, high titratable acidity, pH below the critical value and high viscosity which can be considered risk factors for dental caries and erosion, when consumed frequently.

In situ Effect of Chewing Gum with and without CPP-ACP on Enamel Surface Hardness Subsequent to ex vivo Acid Challenge

The erosion-protective effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is controversial. This study aimed to investigate the ability of CPP-ACP chewing gum to prevent a single event of erosive demineralization in situ. Bovine enamel blocks (n = 120) were randomly assigned to 3 phases according to the baseline surface hardness: phase I (PI) - chewing gum with CPP-ACP, phase II (PII) - chewing gum without CPP-ACP, and control phase (PIII) - salivary effect without stimulation (no gum). Nineteen volunteers participated in this study during 3 crossover phases of 2 h. In PI and PII, the volunteers wore intraoral palatal appliances for 120 min and chewed a unit of the corresponding chewing gum for the final 30 min. In the control phase the volunteers wore the appliance for 2 h, without chewing gum. Immediately after intraoral use, the appliances were extraorally immersed in a cola drink for 5 min to promote erosive demineralization. The percentage of surface hardness loss was calculated. The data were analyzed by ANOVA models and Tukey's test. Lower enamel hardness loss was found after the use of chewing gum with CPP-ACP (PI: 32.7%) and without CPP-ACP (PII: 33.5%) compared to the salivary effect without stimulation (PIII: 39.8%) (p < 0.05). There was no difference between PI and PII (p > 0.05). The results suggest that the use of chewing gum immediately before an erosive demineralization can diminish enamel hardness loss. However, the presence of CPP-ACP in the chewing gum cannot enhance this protective effect.

Comparative evaluation of surface properties of enamel and different esthetic restorative materials under erosive and abrasive challenges: An in vitro study

Introduction:

Noncarious tooth surface loss is a normal physiological process occurring throughout the life, but it can often become a problem affecting function, esthetics or cause pain.

Aim:

The purpose of this study was to assess the effect of erosive and abrasive challenges on the surface microhardness and surface wear of enamel and three different restorative materials, that is, nanofilled composite, microfilled composite and resin-modified glass ionomer cement (RMGIC) by using Vickers microhardness tester and profilometer respectively.

Subjects and Methods:

Nanofilled composite (Filtek^™ Z350 × T), microfilled composite (Heliomolar^®) and RMGIC (Fuji II LC) were used in the study.

Results:

Nanofilled composite resin has the best resistance to erosion and/or abrasion among all the materials tested, followed by microfilled composite and RMGIC respectively.

Conclusion:

Toothbrush abrasion has a synergistic effect with erosion on substance loss of human enamel, composites, and RMGIC. The susceptibility to acid and/or toothbrush abrasion of human enamel was higher compared to restorative materials.

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.

In situ remineralizing effect of fluoride varnishes containing sodium trimetaphosphate

OBJECTIVE

This study analyzed the effects of a fluoride (F) varnish supplemented with sodium trimetaphosphate (TMP) on the remineralization of caries-like lesions in situ.

MATERIALS AND METHODS

Twelve subjects used palatal devices with demineralized enamel discs for 3 days, following a double-blind, crossover protocol. Test groups included placebo (no F or TMP), 5% NaF and 5% NaF/5% TMP varnishes. The percentage of surface hardness recovery (%SHR) and cross-sectional hardness (ΔKHN) were determined.

RESULTS

Significant differences were observed among all varnishes regarding %SHR and ΔKHN. The highest %SHR and the lowest ΔKHN were seen for the 5% NaF/5% TMP varnish, followed by 5% NaF and placebo.

CONCLUSION

The remineralizing effect of a 5% NaF varnish is significantly enhanced when associated with TMP.

CLINICAL RELEVANCE

The reduction in the subsurface lesion area of enamel treated with the TMP-containing varnish implies that cavities would take longer to develop or might not develop at all depending on individual factors, resulting in lower net caries increments at individual and population levels.

Effect of toothpaste with nano-sized trimetaphosphate on dental caries: In situ study

OBJECTIVES

This in situ study was to evaluate the remineralizing effect of a fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate (TMP).

METHODS

This blind and cross-over study was performed in 4 phases of 3 days each. Twelve subjects used palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned into the following treatment groups: Placebo (without F and TMP); 1100 ppm F (1100), 1100 supplemented with 3% micrometric TMP (1100 TMP) and with nano-sized TMP (1100 TMPnano). Volunteers were instructed to brush their natural teeth with the palatal appliances in the mouth during 1min (3 times/day), so that blocks were treated with natural slurries of toothpastes. After each phase, the percentage of surface hardness recovery (%SHR), integrated mineral recovery (IMR) and integrated differential mineral area profile (ΔIMR) in enamel lesions were calculated. F in enamel was also determined. Data were analyzed by ANOVA and Student-Newman-Keuls test.

RESULTS

Enamel surface became 20% harder when treated with 1100 TMPnano in comparison with 1100 (p<0.001). 1100 TMPnano showed remineralizing capacity (IMR; ΔIMR) 66% higher when compared with 1100 TMP (p<0.001). Enamel F uptake in the 1100 TMPnano group was 2-fold higher when compared to its counterpart without TMP (p<0.001).

CONCLUSION

The addition of 3% TMPnano to a conventional toothpaste was able to promote an additional remineralizing effect of artificial caries lesions.

CLINICAL SIGNIFICANCE

Toothpaste containing 1100 ppm F associated with TMPnano showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric TMP.

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.

In situ effect of a commercial CPP-ACP chewing gum on the human enamel initial erosion

OBJECTIVE

This study evaluated the in situ rehardening effect of a commercial chewing gum containing casein phosphopeptide - amorphous calcium phosphate (CPP-ACP) on initial erosion lesions.

METHODS

Seventy-two human enamel blocks, after selection (initial surface hardness - SHi) and in vitro short-term acidic exposure (cola drink for 3 min - SHd) were randomly assigned to three groups. The factors under study were treatment (3 levels: GI chewing gum with CPP-ACP, GII chewing gum without CPP-ACP and GIII control group without gum) and intraoral period (2 levels: 2 and 24h). Twelve volunteers wore intraoral palatal devices for 24h in 3 crossover phases. On each phase, after 2h the surface hardness was assessed (SHf1) and the blocks were reinserted and the devices were used for additional 22 h (SHf2). In phases of GI and GII volunteers chewed the respective gum during 30 min, for 4 times with an interval of 4h. Percentage of surface hardness recovery (%SHR) was calculated after 2 and 24 h. The data were analysed by repeated measures ANOVA and Tukey's test.

RESULTS

Chewing gum with CPP-ACP (2h=50.0%<24h=95.9%) showed higher hardness recovery than chewing gum without CPP-ACP (2h=30.0%<24 h=71.1%) and control (2 h=15.7%<24 h=40.9%) (p<0.05).

CONCLUSIONS

The results suggest that saliva increased hardness of softened enamel after the use of conventional chewing gum (GII) and this effect was enhanced by the prolonged intraoral period (24 h) and by the use of CPP-ACP chewing gum (GI).

CLINICAL SIGNIFICANCE

Since chewing gum is an alternative to enhance salivary defenses after erosive challenges, CPP-ACP chewing gum might be a supplementary strategy to potentiate the mineral precipitation of initial erosion lesions.

Use of dentifrices to prevent erosive tooth wear: harmful or helpful?

Dental erosion is the loss of dental hard tissues caused by non-bacterial acids. Due to acid contact, the tooth surface becomes softened and more prone to abrasion from toothbrushing. Dentifrices containing different active agents may be helpful in allowing rehardening or in increasing surface resistance to further acidic or mechanical impacts. However, dentifrices are applied together with brushing and, depending on how and when toothbrushing is performed, as well as the type of dentifrice and toothbrush used, may increase wear. This review focuses on the potential harmful and helpful effects associated with the use of dentifrices with regard to erosive wear. While active ingredients like fluorides or agents with special anti-erosive properties were shown to offer some degree of protection against erosion and combined erosion/abrasion, the abrasive effects of dentifrices may increase the surface loss of eroded teeth. However, most evidence to date comes from in vitro and in situ studies, so clinical trials are necessary for a better understanding of the complex interaction of active ingredients and abrasives and their effects on erosive tooth wear.

Impact of bariatric surgery on oral health conditions: 6-months cohort study

OBJECTIVES

We evaluate oral health conditions before and after bariatric surgery.

METHODS

The sample was composed of 59 patients who had undergone Roux-en-Y gastric bypass (RYGB). Salivary flow, periodontal pocket depth and dental wear were evaluated before and after 6 months of surgery. Body mass index (BMI), C-reactive protein (CRP) and glucose levels were obtained from the patient's medical files. A t-test was used for dependent samples.

RESULTS

The mean BMI decreased from 49.31 ± 8.76 to 35.52 ± 8.12 kg/m(2) in 6 months after surgery (P < 0.000). Before surgery, 67% of patients had high levels of CRP and 38% higher blood glucose levels and after surgery there were significant reductions in these levels (P < 0.001). Salivary flow ranged from 0.84 to 0.95 ml/min. There was increased prevalence of periodontal pockets (P = 0.022) and mean pocket depth increased to about 0.5 mm (P < 0.001). The percentage of surfaces with dental wear in dentine was significantly higher after bariatric surgery (P = 0.002), while dental wear in enamel decreased (P = 0.019).

CONCLUSIONS

Bariatric surgery may improve systemic conditions. However, it had a negative impact on oral health conditions because of an increase in periodontal disease and dental wear.

Effect of Toothpastes with Different Abrasives on Eroded Human Enamel: An in situ/ex vivo Study

The aim of the present study was to investigate the abrasive effect of CaCO₃ and SiO₂-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immersed in a soft drink for five minutes four times a day (9:00 am, 11:00 am, 2:00 pm and 4:00 pm). On two occasions, two blocks were not submitted to additional treatment; two blocks were brushed (30 s) either with a CaCO₃ or SiO₂ toothpaste immediately after erosion and two blocks were brushed 1 h after erosion. Thus, the sample was divided into six groups: erosion alone (CaCO₃ and SiO₂ control); brushing with fluoride-free toothpaste (CaCO₃ immediate and 1 h after erosion; SiO₂ immediate and 1 h after erosion). Significant differences in wear depth were found between the enamel blocks in the CaCO₃ immediate and 1 h after erosion groups and the blocks in the CaCO₃ control group (p=0.001; p=0.022). No significant differences were found regarding the change in roughness and wear depth between blocks submitted to immediate abrasion and 1 h after erosion (CaCO₃ and SiO₂). The data revealed that surface roughness and wear depth is increased when erosion is combined with dental abrasion, regardless of the abrasive used. Waiting for 1 h to brush the eroded blocks offered no protective effect.

Saliva and dental erosion

Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear.

OBJECTIVE

This review discusses the role of salivary factors on the development of dental erosion.

MATERIAL AND METHODS

A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party.

RESULTS

Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion.

CONCLUSIONS

Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Iron supplementation reduces the erosive potential of a cola drink on enamel and dentin in situ

Iron has been suggested to reduce the erosive potential of cola drinks in vitro.