Influence of Prolonged Tooth Bleaching on Enamel Mass Variation / Influencia del Blanqueo Dental Prolongado en la Variación de Masa del Esmalte Dental

ABSTRACT: The objective evaluate was the influence of prolonged tooth bleaching with 10 % carbamide peroxide (10CP) on tooth enamel mass variation. Ten healthy bovine incisor teeth were divided (n = 5) into G1 - storage in distilled water and G2 - storage in artificial saliva. The samples were weighed in an electronic analytical balance at the following times: T0 - before application of the bleaching gel, T1 - after 14 days of bleaching (the time recommended by the manufacturer), T2 - after 21 days of bleaching (50 % increase in the time recommended by the manufacturer), and T3 - after 28 days of bleaching (100 % increase in the time recommended by the manufacturer). The data were subjected to ANOVA for related samples (p = 0.05). The highest mean was observed in G2 (0.5982 g) and the lowest mean was observed in G1 (0.3074 g) at T2 and T3, respectively. Significant differences were observed between the groups at all times. Overall, 10CP caused variation in the enamel mass after a 100 % increase in the use time recommended by the manufacturer, with a decrease in mass when distilled water was used as the storage medium and an increase when artificial saliva was used.

RESUMEN: El objetivo fue investigar la influencia del blanqueamiento dental prolongado con peróxido de carbamida al 10 % (10CP) sobre la variación de masa del esmalte dental. Las muestras se dividieron en dos grupos: G1, diez dientes sanos de los incisivos bovinos (n = 5) en agua destilada, y G2, almacenamiento en saliva artificial. Las muestras se midieron en una escala analítica electrónica de precisión en los siguientes tiempos: T0-antes de la aplicación del gel blanqueador, T1-después de 14 días de blanqueo (el tiempo recomendado por el fabricante), T2-después de 21 días de blanqueo (aumento de 50 % en el tiempo recomendado por el fabricante), y T3-después de 28 días de blanqueo (aumento de 100 % en el tiempo recomendado por el fabricante). Los datos se presentaron al ANOVA para las muestras relacionadas (P = 0,5). La media más alta se observó en G2 (0,5982 g) y la media más baja se observó en G1 (0,3074 g) en T2 y T3, respectivamente. Se observaron diferencias significativas entre los grupos en todo momento. En general, la 10 CP causó variación en la masa del esmalte después de un aumento de 100 % en el tiempo de uso recomendado por el fabricante, con una disminución en la masa cuando el agua destilada se utilizó como medio de almacenamiento y aumentó cuando se usó saliva artificial.

Novel methodology for determining the effect of adsorbates on human enamel acid dissolution.

OBJECTIVE: The effect of various interventions on enamel demineralisation can be determined by chemically measuring mineral ions dissolved by the attacking acid. Results are usually expressed as mineral loss per surface area of enamel exposed. Acid resistant varnish or adhesive tape are typically used to delineate an area of enamel. However, enamel surface curvature, rugosity and porosity reduce the reliability of simple area measurements made at the macro scale. Our aim was to develop a simple method for investigating the effect of adsorbates on enamel demineralisation that does not rely on knowing the area of enamel exposed. As an exemplar we have used salivary proteins as a model adsorbate. DESIGN: Natural human tooth enamel surfaces were subjected to five sequential acid challenges and then incubated in adsorbate (whole clarified saliva) followed by a further 15 acid challenges. Demineralisation was determined by measuring the phosphate released into the acid during each exposure by a spectrophotometric assay. The initial five challenges established a mean baseline mineral loss for each tooth against which the effect of subsequently adsorbed proteins could be compared. RESULTS: Salivary proteins significantly reduced the acid demineralisation of human enamel by 43% (p<0.01). Loss of proteins during each challenge corresponded to a gradual reduction in the degree of protection afforded. CONCLUSIONS: The methodology provides a simple and flexible means to investigate the effect of any adsorbate on enamel acid dissolution. Knowledge of the area of exposed enamel is irrelevant as each tooth acts as its own negative control.

Influence of tooth bleaching on dental enamel microhardness: a systematic review and meta-analysis.

Several studies have investigated the effect of bleaching on dental tissues. The evaluation of the effect of home bleaching with 10% carbamide peroxide is important for assessing alterations in enamel microhardness that may affect dental health in terms of resistance to masticatory forces. This meta-analysis was performed in order to determine scientific evidence regarding the effects of home vital bleaching with 10% carbamide peroxide gel on the microhardness of human dental enamel. A systematic electronic literature search was conducted in the PubMed and Web of Science databases using search terms. Two independent researchers evaluated the information and methodological quality of the studies. Inclusion and exclusion criteria were established for article selection; further, only studies published in English were selected. Thirteen studies that met all of the inclusion and exclusion criteria were selected and underwent statistical analysis. The results of this meta-analysis showed no significant changes in enamel microhardness when using the 10% carbamide peroxide bleaching gel over periods of 7, 14 and 21 days.

Identification of acid-resistant proteins in acquired enamel pellicle.

OBJECTIVES: This study characterized the proteome profile of the acquired pellicle formed in vivo on enamel. Changes in this proteome profile after exposure to lactic or citric acid were also evaluated. METHODS: Volunteers (n=8) were subjected to dental prophylaxis. After 2 h to allow the formation of the acquired pellicle, the teeth were isolated with cotton rolls and 1 mL of citric acid (1%, pH 2.5) or lactic acid (0.1 M pH 4.8) or deionized water was gently applied with a pipette on the anterior teeth (both maxillary and mandibular) for 10 s. In sequence, the pellicle was collected with an electrode filter paper soaked in 3% citric acid. This procedure was repeated for two additional days following a crossover protocol. Proteins were subjected to reverse phase liquid chromatography coupled to mass spectrometry (nLC-ESI-MS/MS). MS/MS data were processed and submitted to Proteome Discoverer software. Searches were done using SWISS-PROT and TrEMBL databases for human proteins. RESULTS: In total, seventy-two proteins were present in all groups and were submitted to quantitative analysis (SIEVE). Some of these proteins were increased more than two-fold after exposure to the acids. Among them, cystatin-B was increased 20- and 13-fold after exposure to citric and lactic acids, respectively. Additionally, some proteins were identified in only one of the groups (18, 5, and 11 proteins for deionized water, citric and lactic acids, respectively). CONCLUSIONS: Our results open new insights regarding potentially acid-resistant proteins that could be added to dental products to prevent acidic dissolution of the teeth.

Measurement of the efficacy of calcium silicate for the protection and repair of dental enamel.

OBJECTIVES: To investigate the formation of hydroxyapatite (HAP) from calcium silicate and the deposition of calcium silicate onto sound and acid eroded enamel surfaces in order to investigate its repair and protective properties. METHODS: Calcium silicate was mixed with phosphate buffer for seven days and the resulting solids analysed for crystalline phases by Raman spectroscopy. Deposition studies were conducted on bovine enamel surfaces. Acid etched regions were produced on the enamel surfaces using scanning electrochemical cell microscopy (SECCM) with acid filled pipettes and varying contact times. Following treatment with calcium silicate, the deposition was visualised with FE-SEM and etch pit volumes were measured by AFM. A second set of bovine enamel specimens were pre-treated with calcium silicate and fluoride, before acid exposure with the SECCM. The volumes of the resultant acid etched pits were measured using AFM and the intrinsic rate constant for calcium loss was calculated. RESULTS: Raman spectroscopy confirmed that HAP was formed from calcium silicate. Deposition studies demonstrated greater delivery of calcium silicate to acid eroded than sound enamel and that the volume of acid etched enamel pits was significantly reduced following one treatment (p<0.05). In the protection study, the intrinsic rate constant for calcium loss from enamel was 0.092 ± 0.008 cm/s. This was significantly reduced, 0.056 ± 0.005 cm/s, for the calcium silicate treatments (p<0.0001). CONCLUSIONS: Calcium silicate can transform into HAP and can be deposited on acid eroded and sound enamel surfaces. Calcium silicate can provide significant protection of sound enamel from acid challenges. CLINICAL SIGNIFICANCE: Calcium silicate is a material that has potential for a new approach to the repair of demineralised enamel and the protection of enamel from acid attacks, leading to significant dental hard tissue benefits.

Erosion in relation to nutrition and the environment.

When considering the erosive potential of a food or drink, a number of factors must be taken into account. pH is arguably the single most important parameter in determining the rate of erosive tissue dissolution. There is no clear-cut critical pH for erosion as there is for caries. At low pH, it is possible that other factors are sufficiently protective to prevent erosion, but equally erosion can progress in acid of a relatively high pH in the absence of mitigating factors. Calcium and phosphate concentration, in combination with pH, determine the degree of saturation with respect to tooth minerals. Solutions supersaturated with respect to enamel or dentine will not cause them to dissolve, meaning that given sufficient common ion concentrations erosion will not proceed, even if the pH is low. Interestingly, the addition of calcium is more effective than phosphate at reducing erosion in acid solutions. Today, several calcium-enriched soft drinks are on the market, and acidic products with high concentrations of calcium and phosphorus are available (such as yoghurt), which do not soften the dental hard tissues. The greater the buffering capacity of the drink or food, the longer it will take for the saliva to neutralize the acid. A higher buffer capacity of a drink or foodstuff will enhance the processes of dissolution because more release of ions from the tooth mineral is required to render the acid inactive for further demineralization. Temperature is also a significant physical factor; for a given acidic solution, erosion proceeds more rapidly the higher the temperature of that solution. In recent years, a number of interesting potentially erosion-reducing drink and food additives have been investigated.

Remineralizing efficacy of different calcium-phosphate and fluoride based delivery vehicles on artificial caries like enamel lesions.

OBJECTIVES: To assess enamel remineralization of different calcium-phosphate and fluoride delivery systems. METHODS: Artificial caries lesions were created on 115 extracted human molars. Specimens were assigned according to remineralizing agent into five groups: G1: Control (artificial saliva), G2: Clinpro™ white varnish, G3: Relief, G4: Tooth Mousse Plus, G5: Vanish™XT. Surface micro-hardness (SMH), surface roughness (Ra) and surface topography by scanning electron microscope (SEM) were evaluated at baseline, after demineralization, after 2 and 4 weeks remineralization and after acid challenge. RESULTS: Demineralized enamel showed the lowest SMH. By 2 weeks remineralization, SMH were ranked as follows: G2 (282.14±6.82)>G3 (269.37±7.25)>G5 (263.00±6.49)=G4 (251.83±8.26)>G1 (226.5±9.34). However, 4 weeks remineralization showed the following: G2 (304.09±6.65)>G3 (293.1±5.24)=G4 (285±7.29)>G5 (272.43±4.89)>G1 (233.33±9.12). By exposure to acid challenge, groups presented order of: G2 (279.71±5.99)=G3 (275.51±5.59)>G4 (262.29±6.65)>G5 (245.43±6.43)>G1 (190.27±8). Surface roughness showed the following mattress after 2 weeks remineralization: G1 (0.2488±0.0016)=G2 (0.2487±0.0007)=G3 (0.2476±0.0006)>G4 (0.2442±0.0004)>G5 (0.2396±0.0009). After 4 weeks remineralization: G1 (0.2469±0.0017)>G4 (0.244±0.0004)>G5 (0.2413±0.0008)=G3 (0.2405±0.0007)=G2 (0.2399±0.0006). After acid challenge; G1 (0.2582±0.0027)>G5 (0.2556±0.0007)>G4 (0.2484±0.0009)>G3 (0.2463±0.0007)>G2 (0.2443±0.0004). SEM revealed mineralized coating on the surfaces which resists dissolution by acid challenge at variable degrees according to remineralization regimen applied. CONCLUSIONS: Remineralizing agents containing different calcium-phosphate formulas and fluoride have increased remineralization potential compared to artificial saliva. Clinpro™ varnish presented the highest remineralization tendency with greatest resistance for acid challenge. CLINICAL SIGNIFICANCE: This in vitro study imitated the application of different calcium phosphorous and fluoride based delivery vehicles to enamel tooth surfaces in the mouth. The new therapeutic techniques based on different calcium phosphate formulas containing fluoride provide a new avenue for remineralization of non-cavitated and early carious lesions.

Numerical modelling of tooth enamel subsurface lesion formation induced by dental plaque.

Using a one-dimensional mathematical model that couples tooth demineralisation and remineralisation with metabolic processes occurring in the dental plaque, two mechanisms for subsurface lesion formation were evaluated. It was found that a subsurface lesion can develop only as the result of alternating periods of demineralisation (acid attack during sugar consumption) and remineralisation (resting period) in tooth enamel with uniform mineral composition. It was also shown that a minimum plaque thickness that can induce an enamel lesion exists. The subsurface lesion formation can also be explained by assuming the existence of a fluoride-containing layer at the tooth surface that decreases enamel solubility. A nearly constant thickness of the surface layer was obtained with both proposed mechanisms. Sensitivity analysis showed that surface layer formation is strongly dependent on the length of remineralisation and demineralisation cycles. The restoration period is very important and the numerical simulations support the observation that often consumption of sugars is a key factor in caries formation. The calculated profiles of mineral content in enamel are similar to those observed experimentally. Most probably, both studied mechanisms interact in vivo in the process of caries development, but the simplest explanation for subsurface lesion formation remains the alternation between demineralisation and remineralisation cycles without any pre-imposed gradients.

Comparison of the enamel solubility reduction from Various prescription and OTC fluoride toothpastes and gels.

OBJECTIVE: The purpose of this in vitro study was to determine if a novel 970 ppm F ion SnF2OTC gel (Enamelon Preventive Treatment Gel) and a 1150 ppm F- ion SnF2OTC Enamelon Toothpaste, each delivering amorphous calcium phosphate (ACP), can significantly reduce the effect of an acid challenge to enamel as compared to two prescription (Rx) strength 5000 ppm F- ion (NaF) dentifrices containing tri-calcium phosphate (TCP), and an Rx 900 ppm F- ion (NaF) paste with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). The effect will be determined by measuring the resistance of enamel specimens to an acid challenge before and after treatment with the test dentifrices. METHODS: The procedure used in this study was the FDA Test Method #33 for the determination of the effect of different test dentifrices on enamel solubility reduction. Twelve sets of three extracted human teeth were unprotected and etched prior to treatment with 0.1 M lactic acid buffer solution. The amount of phosphate dissolved from the teeth was quantified via measuring the phosphate in the retained lactate buffer solution with phosphorous analysis (pre-treatment phosphorous levels). The teeth sets were then exposed to the following treatments (diluted 1:3 parts in preheated [37 degrees C] distilled water): 5000 ppm F- ion, sodium fluoride (NaF) Rx dentifrice containing TCP; 5000 ppm F- ion, NaF Rx dentifrice; 900 ppm F- ion, NaF Rx paste with CPP-ACP; 1150 ppm F- ion, stannous fluoride (SnF2) OTC toothpaste delivering ACP Enamelon Toothpaste; and 970 ppm F- ion, SnF2 OTC gel delivering ACP (Enamelon Preventive Treatment Gel). The teeth sets were rinsed with distilled water and then exposed to 0.1 M buffered lactic acid solution. The amount of phosphate in the lactic acid buffer was determined for a second time (post-treatment phosphorous levels). The percent of enamel solubility reduction was then computed as the difference between the amount of phosphorous in the pre- and post-treatment lactic acid solutions divided by the amount of phosphorous in the pre-treatment solution, and multiplied by 100. RESULTS: The percent reduction in enamel solubility recorded in this study was as follows: 60.14 ± 0.79 for the Enamelon Toothpaste; 56.91 ± 1.05 for the Enamelon Preventive Treatment Gel; 18.78 ± 3.20 for the 5000 ppm F- ion, NaF prescription dentifrice "A' with TCP; 6.84 ± 1.20 for the 900 ppm F- ion, NaF paste with CPP-ACP; 5.82 ± 3.10 for the 5000 ppm F- ion, NaF prescription dentifrice "B" with TCP; and -5.45 ± 1.86 for the negative control. The differences between all the products tested were statistically significant (p < 0.05), except for the Enamelon products that were not statistically different. The 900 ppm F- ion, NaF paste with CPP-ACP and the 5000 ppm F- ion, NaF toothpaste results were also not statistically different. CONCLUSION: The Enamelon products (970 ppm and 1150 ppm F- ion, SnF2 OTC dentifrices) delivering ACP were statistically significantly more effective in reducing enamel solubility than two Rx strength 5000 ppm F- ion NaF toothpastes containing TCP and the Rx 900 ppm F- ion NaF paste containing CPP-ACP.

A new model for demonstrating enamel protection benefits relative to acid challenge.

OBJECTIVE: To determine the applicability of a modified US FDA Caries Monograph test method for measuring the protective benefits of fluoride (F) against erosive, dietary acids. METHODS: Acid-challenged teeth were treated in two studies with a dentifrice, rinsed, and then re-challenged in a series of tests using three dietary acids. Study 1 included dentifrices containing 1450 ppm F as sodium fluoride (NaF) + triclosan [A], 1450 ppm F (NaF) + potassium nitrate (KNO3) [B], 1000 ppm F as sodium monofluorophosphate (SMFP) [C], and 0 ppm F (placebo) [D]. Study 2 included dentifrices containing 1450 ppm F (NaF) [A]; and 0 ppm F (placebo) [B]. Acids were analyzed for phosphate removed during tooth challenges, with post-treatment results compared to baseline. Results were averaged and reported as a % protection value for each product, with higher values indicating greater protection. RESULTS: Study 1: % protection for A = 16.4; B = 13.0; C = 7.1; and D = -5.2. Study 2: A = 15.2; B = -10.5, with A = B > C > D: Study 1; and A > B: Study 2. In each study, p < 0.05, ANOVA. CONCLUSIONS: The model provides a viable tool for initially assessing the potential for fluoride-containing oral care products to protect teeth against erosive, dietary acids. This can then lead to further and more elaborate testing with reasonable expectations for outcomes.

Effects of buffering properties and undissociated acid concentration on dissolution of dental enamel in relation to pH and acid type.

To quantify the relationships between buffering properties and acid erosion and hence improve models of erosive potential of acidic drinks, a pH-stat was used to measure the rate of enamel dissolution in solutions of citric, malic and lactic acids, with pH 2.4-3.6 and with acid concentrations adjusted to give buffer capacities (ß) of 2-40 (mmol·l(-1))·pH(-1) for each pH. The corresponding undissociated acid concentrations, [HA], and titratable acidity to pH 5.5 (TA5.5) were calculated. In relation to ß, the dissolution rate and the strength of response to ß varied with acid type (lactic > malic ≥ citric) and decreased as pH increased. The patterns of variation of the dissolution rate with TA5.5 were qualitatively similar to those for ß, except that increasing pH above 2.8 had less effect on dissolution in citric and malic acids and none on dissolution in lactic acid. Variations of the dissolution rate with [HA] showed no systematic dependence on acid type but some dependence on pH. The results suggest that [HA], rather than buffering per se, is a major rate-controlling factor, probably owing to the importance of undissociated acid as a readily diffusible source of H(+) ions in maintaining near-surface dissolution within the softened layer of enamel. TA5.5 was more closely correlated with [HA] than was ß, and seems to be the preferred practical measure of buffering. The relationship between [HA] and TA5.5 differs between mono- and polybasic acids, so a separate analysis of products according to predominant acid type could improve multivariate models of erosive potential.

Enamel protection from acid challenge--benefits of marketed fluoride dentifrices.

OBJECTIVE: To determine the ability of various marketed dentifrices containing stabilized stannous fluoride (SnF2), sodium fluoride (NaF), or sodium monofluorophosphate (SMFP) to protect enamel against the earliest stages of erosive dietary acid damage using an in vitro enamel protection model. METHODS: Acid-challenged, extracted human teeth were treated with a 1:3 dilution of dentifrice, rinsed, and then challenged in a controlled series of tests using four dietary acids considered potentially erosive to teeth. Each acid was collected and analyzed to determine the level of mineral (phosphorous) removed from the teeth during the challenge. Post-treatment results were compared to baseline values for each acid. Results for the four acids were averaged and reported as an average percent protection value for each of the dentifrices tested, with higher values representing greater acid protection. The study included six dentifrices formulated with (A) sodium fluoride (NaF), (B) stabilized stannous fluoride (SnF2), (C,D) NaF plus 5% potassium nitrate (KNO3), (E) sodium monofluorophosphate (SMFP), or (F) SMFP plus 8% arginine bicarbonate. RESULTS: The stabilized SnF2 dentifrice demonstrated an average protection score of 39.3%, while products formulated with NaF resulted in protection scores between 11 and 13%. The SMFP dentifrice was rated at -3.5%, and the SMFP + arginine bicarbonate dentifrice resulted in a net average score of -5.0%. Results of this test were statistically significant (p < 0.05, ANOVA: B > A = C = D > E = F), in favor of the stabilized SnF2 dentifrice. CONCLUSIONS: These results suggest the stabilized SnF2 dentifrice has the potential to provide significantly better overall acid protection versus any of the other dentifrices included in the study.

Effects of a novel fluoride-containing aluminocalciumsilicate-based tooth coating material (Nanoseal) on enamel and dentin.

PURPOSE: To investigate the effect of a fluoride-containing aluminocalciumsilicate nanoparticle glass dispersed aqueous solution (Nanoseal) on enamel and dentin, under the hypothesis that this material can form insoluble mineral deposits that confer acid resistance to the tooth structure and occlude open dentin tubules. METHODS: Labial enamel and dentin of human extracted incisors were used. Morphology of the enamel and dentin artificially demineralized with a lactic acid solution that before and/or after coated with the test material were analyzed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with an image observation function (SEM-EPMA). Moreover, incorporation of the calcium and silicon by enamel and dentin were also detected with SEM-EPMA. RESULTS: Application of the fluoroaluminocalciumsilicate-based tooth coating material resulted in the deposition of substances (nanoparticles) onto the enamel surface porosities and open dentin tubules on the artificial lesions. Prior coating with the test material reduced the demineralization-induced loss of enamel and dentin. Moreover, Ca and Si incorporation into superficial enamel and dentin was detected.

Potential mechanism for the laser-fluoride effect on enamel demineralization.

Laser-induced prevention of dental caries has been studied extensively. However, the cariostatic mechanisms of a combined fluoride-laser treatment are not well-understood. Using micro- computed tomography (micro-CT), we quantified the effect of fluoride and/or Er:YAG laser treatment on enamel demineralization. The mean mineral loss (%/V) for each group was 4,870 ± 1,434 (fluoride followed by laser treatment), 6,341 ± 2,204 (laser treatment), 7,669 ± 2,255 (fluoride treatment), and 10,779 ± 2,936 (control). The preventive effect of the laser (p < 0.001) and fluoride (p = 0.010) treatment was statistically significant. Characterized by micro-x-ray diffraction (XRD) analysis, the significant contraction in the a-axis after both laser and combined laser/fluoride treatment was revealed (both p < 0.05). In conclusion, subablative low-energy Er:YAG laser irradiation following fluoride treatment may instantaneously transform enamel hydroxyapatite into fluoridated hydroxyapatite to reduce enamel solubility as a preventive treatment for enamel demineralization.

SEM investigation on casein phosphopeptides capability in contrasting cola drinks enamel erosion: an in vitro preliminary study.

AIM: Erosion of dental hard tissues induced by acidic dietary components is a high-prevalence finding, especially among children and adolescents. Acidic soft drinks are frequently implicated in dental erosion. The aim of this in vitro study was to assess if CPP-ACP preparation is capable of reducing enamel erosion caused by a cola-type drink. MATERIALS AND METHODS: Twenty-five sound human permanent premolars, extracted for orthodontic reasons in patients of 12-16 years old, were used. The roots were removed and the crowns were sectioned in order to obtain 3 enamel sections from each tooth. The specimens were immersed in: (A) cola-type drink; (B) cola-type drink plus CPP-ACP; (C) deionised water (control) for: 48 h, 24 h, 12 h, 6 h and 3 h, respectively. pH values were constantly monitored. Statistical analysis was performed using ANOVA. The enamel samples were evaluated for surface changes using scanning electron microscopy (SEM). RESULTS: Specimens subjected to cola-type drink (treatment A) showed wide areas of enamel dissolution, while the treatment B specimens showed a few areas of little enamel erosion, different from control samples. Adding CPP-ACP to the cola-type drinks influenced pH levels of the solutions, but always in the acidity range. CONCLUSION: CPP-ACP provides protection against dental erosion from cola-type drinks in vitro. Therefore, further studies are necessary to evaluate if adding casein phosphopeptide-stabilised amorphous calcium phosphate complex to acidic cola drinks could reduce their erosive potential in vivo as well.

Cross-sectional microhardness of bovine enamel subjected to three paediatric liquid oral medicines: an in vitro study.

AIM: This study aimed to investigate the in vitro effects of three paediatric liquid oral medicines on bovine dental enamel subsurfaces under pH cycling conditions. METHODS: Bovine enamel blocks were evaluated for surface hardness at baseline for sample selection. 52 intact bovine enamel blocks (16mm(2)) were randomly divided into four groups (n=13) according to the immersion treatments: G1: antibiotic (Klaricid®), G2: antihistamine (Claritin®), G3: antihistamine (Dimetapp®) and G4: control (de-ionised water). The blocks were submitted to pH cycling treatments twice a day for 12 days. The medicines were evaluated for pH, viscosity, and concentration of calcium, phosphate and fluoride. After the treatment period, cross-sectional microhardness (CSMH) measurements of the enamel blocks were taken and the data, expressed in Knoop hardness number (kg/mm(2)) was used to calculate the ΔS. STATISTICS: ANOVA followed by the Tukey test were used for statistical analyses (p<0.05). RESULTS: The antibiotic Klaricid® showed the highest concentration of fluoride, calcium and phosphate. Considering pH and viscosity, the following pattern was observed according to the treatment group: G4>G1>G2>G3 and G1>G2>G3>G4 respectively. Regarding the demineralisation pattern, the following results were observed: G4>G3>G2>G1. Compared to the control, the antibiotic and both the antihistamines provoked less demineralisation of the enamel blocks (p<0.05). CONCLUSIONS: Antibiotic G1 (Klaricid®) presented an in vitro protective effect against acid attacks probably due to its mineral content and viscosity.

Protection of sound enamel and artificial enamel lesions against demineralisation: caries infiltrant versus adhesive.

OBJECTIVE: To compare the protective potential of a conventional adhesive, a caries infiltrant and a combination of both against acidic challenge in vitro. METHODS: One-hundred-and-fifty discs from bovine lower central incisors were fabricated. Seventy-five samples remained untreated, whereas the other half was subjected to a demineralisation process (14 days, acidic buffer, and pH 5) to create artificial enamel lesions. Specimens were then radioactively irradiated, and each 15 sound and demineralised specimens were treated with a caries infiltrant (Icon, DMG), an unfilled adhesive (Heliobond, IvoclarVivadent) or a combination of infiltrant and adhesive. Specimens treated with the adhesive followed by a flowable composite (TetricEvoFlow, IvoclarVivadent) served as positive control, while untreated specimens served as negative control. All samples were then subjected to lactic acid for 3 weeks at pH 4. Loss of apatite was determined using the radiochemical method of liquid scintillation. Data were statistically analysed by Kruskal-Wallis-test, one-way ANOVA and Scheffe's post hoc tests (p ≤.05). RESULTS: In both sound enamel and artificial caries lesions, untreated specimens showed the highest rate of apatite loss, whereas enamel treated with the adhesive and the flowable composite showed almost complete protection surface against dissolution. The caries infiltrant, the adhesive and the combination of both were able to decrease enamel dissolution, but the adhesive and the combination of adhesive and infiltrant were more effective than the infiltrant alone. CONCLUSION: Within the limitations of this in vitro study, the application of an adhesive (alone or in combination with the caries infiltrant) is more effective to protect enamel dissolution than the infiltrant alone.

Mineral ions in the fluid of biofilms formed on enamel and dentine shortly after sugar challenge.

To test the effect of distinct solubilities of dentine and enamel on mineral ion concentration in the biofilm fluid during a sugar-induced pH drop, dental biofilms were formed in situ for 4 days on acrylic (control), dentine or enamel. On the 5th day, they were treated with water (control) or 20% glucose and collected 5 min later. Significantly lower pH values and higher calcium concentrations were found in the biofilm fluid after glucose exposure, without significant differences among the three substrates. During pH drop, biofilm reservoirs release calcium to the fluid, masking the differential solubility between enamel and dentine.

A comparison of sports and energy drinks--Physiochemical properties and enamel dissolution.

The consumption of sports and energy drinks by children and adolescents has increased at an alarming rate in recent years. It is essential for dental professionals to be informed about the physiochemical properties of these drinks and their effects on enamel. The present study measured the fluoride levels, pH, and titratable acidity of multiple popular, commercially available brands of sports and energy drinks. Enamel dissolution was measured as weight loss using an in vitro multiple exposure model consisting of repeated short exposures to these drinks, alternating with exposure to artificial saliva. The relationship between enamel dissolution and fluoride levels, pH, and titratable acidity was also examined. There was a statistically significant difference between the fluoride levels (p = 0.034) and pH (p = 0.04) of the sports and energy drinks studied. The titratable acidity of energy drinks (11.78) was found to be significantly higher than that of sports drinks (3.58) (p < 0.001). Five of the energy drinks (Red Bull Sugar Free, Monster Assault, Von Dutch, Rockstar, and 5-Hour Energy) were found to have the highest titratable acidity values among the brands studied. Enamel weight loss after exposure to energy drinks was significantly higher than it was after exposure to sports drinks. The effect of titratable acidity on enamel weight loss was found to vary inversely with the pH of the drinks. The findings indicated that energy drinks have significantly higher titratable acidity and enamel dissolution associated with them than sports drinks. Enamel weight loss after exposure to energy drinks was more than two times higher than it was after exposure to sports drinks. Titratable acidity is a significant predictor of enamel dissolution, and its effect on enamel weight loss varies inversely with the pH of the drink. The data from the current study can be used to educate patients about the differences between sports and energy drinks and the effects of these drinks on tooth enamel.

Effect of pH on Galla chinensis extract's stability and anti-caries properties in vitro.

OBJECTIVES: Considering that Galla chinensis extract (GCE) solution has a low pH, which might dissolve dental enamel, we investigated the effects of elevation of pH on GCE stability, and on its anti-caries properties. DESIGNS: Stability of GCE solutions, either in H(2)O (pH less than 4.0) or when buffered at pH 5.5, 7.0 and 10.0, was assessed from UV-VIS spectra. Inhibition of enamel demineralization was determined in a pH-cycling set up, comprising treatments with either GCE solutions or negative control buffers and acid and neutral buffer immersions. Demineralization was assessed by calcium in the acetate buffers. To determine antimicrobial properties, polymicrobial biofilms were formed after saliva inoculation on glass surfaces which were treated after 48 h. Treatment output parameters were lactic acid formation and viability, the latter by colony forming unit (CFU) counts. RESULTS: At pH 7.0 and higher GCE solutions changed colour and absorption spectra in UV-VIS, indicative of chemical changes. Regarding enamel demineralization, significant inhibitions (P<0.05) were found for all GCE treatments when compared with corresponding controls. In polymicrobial biofilms, GCE reduced the acid production, compared with the negative controls (P<0.05). However, this difference was only significant at the lower pH values. CONCLUSIONS: GCE solutions were unstable under neutral and alkaline conditions. pH did not significantly influence the inhibiting effect of GCE on enamel demineralization. However, GCE was not effective on polymicrobial biofilms at alkaline pH (8.5). To avoid enamel damage due to acidic treatment, GCE solutions should be used at about pH 5.5.