[Influence of fluoride preparations for the prevention of dental caries on the enamel solubility]. / Vliyanie na rastvorimost' emali ftoridsoderzhashchikh preparatov dlya profilaktiki kariesa zubov.

OBJECTIVE: The aim of the study is to evaluate the effectiveness of a number of popular fluorine-containing caries prophylactic drugs by determining the level of solubility of tooth enamel in laboratory conditions. MATERIAL AND METHODS: For testing fluorine-containing preparations, three observation groups were formed: Group I - using the preparation with the content of fluorides 4%; Group II - with a preparation for deep fluoridation of enamel, consisting of a liquid saturated with fluorine, copper and magnesium, as well as a suspension of calcium hydroxide; Group III - with a three-component gel based on carboxymethyl cellulose (CMC) the content of fluorides 1.5%. The study was carried out by using the method of «enamel windows¼ and modeling in the laboratory the processes of both natural and pathological solubility of tooth enamel and determining the level of its solubility by analyzing the decalcifying solution of the oral fluid for the content of calcium and phosphorus ions in it. RESULTS: In the course of the study of fluorinated karyoprophylactic preparations on the enamel surface, according to the observation group, the most active karyoprophylactic fluorinated compositions were identified. CONCLUSION: The data obtained from laboratory studies allow us to formulate clear recommendations for practical health care for the most effective use of the properties of the tested fluorine-containing drugs for prophylactic purposes or in relation to the therapy of focal demineralization of enamel: to obtain the most effective result of the prevention of dental caries in the conditions of practical dental treatment, we recommend applying gel fluoride preparations, and in the treatment of initial caries of the enamel of the teeth, give preference to systems for deep fluoridation of the enamel of the teeth.

Influence of periodic milk or cream treatment on the anti-erosive potential of the acquired enamel pellicle.

OBJECTIVE: The purpose of the present study was to assess the anti-erosive potential of the acquired enamel pellicle formed in situ under the influence of periodic milk or cream treatment. METHODS: The pellicle was formed on bovine enamel specimens in the oral cavity at buccal and palatal sites of upper molars in 6 subjects, using removable acrylic splints. During 6-h of intraoral exposure, splints were removed from the oral cavity every 25 min, treated with milk or cream for 5 min, and subsequently re-inserted into the oral cavity. After 6 h, pellicle covered specimens were immersed in citric acid (0.1 or 1.0 %) for 1 min, and processed for measurement of surface microhardness, determination of calcium release by atomic absorption spectroscopy, scanning and transmission electron microscopy. Statistical analysis was performed with SAS. RESULTS: Statistical analysis did not indicate major differences between erosive surface alterations on enamel specimens covered by pellicles treated with cream or milk, and those covered by control pellicles. In addition, TEM analysis did not reveal any differences concerning the ultrastructure of the different pellicle treatments during acid exposure. All pellicles were dissolved in part after exposure to 0.1 % citric acid and were nearly completely removed after treatment with 1.0% citric acid. CONCLUSIONS: It is concluded that periodic treatment with milk or cream during pellicle formation in situ does not improve the protective potential of the acquired enamel pellicle against erosion. CLINICAL SIGNIFICANCE: Modification of the pellicle by consumption of milk or cream prior to an acidic challenge cannot sufficiently protect enamel from erosion.

Erosive loss of tooth substance is dependent on enamel surface structure and presence of pellicle - An in vitro study.

OBJECTIVE: Aim of this in vitro study was to investigate erosive tooth loss in dependence of the enamel surface structure and presence of an acquired pellicle. METHODS: Enamel specimens from 19 bovine incisors (4 specimens/incisor) were allocated to four experimental groups (n = 19). The surfaces of half of the specimens were polished (two groups), while the other half was left native (two groups). Specimens of one polished and one native group were placed in pooled human saliva (30 min) for the formation of an acquired pellicle. Thereafter, all specimens were demineralized by superfusion with hydrochloric acid (17 min, pH 2.3) with collection of the superfluent. Erosive substance loss was determined by measuring the dissolved calcium content using a colorimetric assay with Arsenazo III reagent. Differences in erosive substance loss were statistically analyzed with respect to enamel surface and pellicle. A linear mixed effects model was fitted to the data and pairwise differences between groups were evaluated (significance level α= 0.05). RESULTS: Enamel surface structure (p < 0.001) and presence of pellicle (p = 0.01) had a significant effect on erosive substance loss. Polished surfaces with pellicle showed the lowest cumulative calcium release [nmol Ca/mm2] (means ± standard deviation: 48+/-5), followed by polished specimens without (51+/-9) and native specimens with pellicle (54+/-10). No significant differences were found between these groups. Highest cumulative calcium release was found for native specimens without pellicle (61+/-9; p < 0.05). CONCLUSIONS: Both enamel surface structure and the acquired pellicle are important determinants of the susceptibility to erosive tooth loss.

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.

Erosion-Protective Capacity of the Salivary Pellicle of Female and Male Subjects Is Not Different.

This study aimed to analyse if the erosion-protective potential of the salivary pellicle is different between female and male subjects. Bovine enamel and dentin specimens (each n = 3) were exposed to the oral cavity of healthy female or male volunteers (each n = 25, females: 25.8 ± 3.5 years, males: 26.7 ± 4.0 years) for 120 min to form a salivary pellicle. Subsequently, each 2 enamel and 2 dentin specimens were eroded with hydrochloric acid (pH 2.6, 60 s). Specimens of the control group (each n = 30) were eroded without presenting a salivary pellicle. Calcium release into the acid was determined photometrically. Additionally, total protein content in the pellicle (each n = 1 enamel and dentin specimen/volunteer) and different salivary parameters (flow rate, pH, buffer capacity, protein, albumin, calcium, phosphate, fluoride) were assessed. Statistical analyses were performed by one-way ANOVA, t tests, multiple linear regressions and Pearson correlations (p < 0.05). The erosion-protective capacity was not significantly different among female (calcium release [% of control]: enamel: 82.6 ± 28.1, dentin: 80.7 ± 24.0) and male (enamel: 76.0 ± 27.5, dentin: 87.1 ± 34.9) subjects. The protein content of the pellicle was not different between female and male subjects. The protein content and pH of unstimulated saliva were significantly reduced in female compared to male volunteers. Calcium release was neither correlated with the protein content of the salivary pellicle nor with salivary parameters. Under the conditions of the present study, the erosion-protective capacity of the salivary pellicle of female and male subjects is not different.

Water sorption and solubility of a nanofilled composite resin protected against erosive challenges / Sorção de água e solubilidade de uma resina composta nanoparticulada protegida contra desafios erosivos

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

Objetivo: Os desafios erosivos capazes de desmineralizar o esmalte também podem promover alterações físicas e mecânicas nos materiais restauradores. O presente trabalho investigou a sorção de água e solubilidade de uma resina composta nanoparticulada submetida a desafios erosivos. Também estudou procedimentos que possam proteger estas superfícies. Material e Métodos: Foram confeccionados 120 corpos de prova. Foram divididos em quatro grupos experimentais, de acordo com o tipo de proteção superficial empregada (controle negativo, aplicação tópica de flúor, verniz de ionômero de vidro modificado por resina e selante resinoso). Após, foram aleatoriamente distribuídos em três subgrupos (n=10) (controle negativo, 9 e 18 ciclos DES-RE). De acordo com a exposição à solução simulada de ácido gástrico (DES) (HCl a 5%, pH=2,2) e posterior remineralização (RE). Os espécimes foram desidratados até obtenção de massa constante e imersos em água destilada por 7 dias, quando foram pesados, e submetidos à nova desidratação. Os valores de sorção e solubilidade foram calculados de acordo as ISSO 4049:2000 e analisados estatisticamente (2-way ANOVA /Tukey, alfa = 5%). Resultados: Independentemente do desafio erosivo recebido, os corpos de prova protegidos com o verniz de ionômero de vidro modificado por resina, apresentaram aumento significativo dos valores de perda e ganho de massa em relação aos demais grupos. Conclusão: Nenhum método de controle apresentou promissora capacidade de proteção superficial da resina composta frente aos desafios erosivos(AU)

Erosive potential of sports beverages on human enamel "in vitro" / Potencial erosivo de bebidas esportivas no esmalte humano "in vitro" / Potencial erosivo de bebidas deportivas en el esmalte humano "in vitro"

INTRODUCTION: The low pH of sports drinks may cause tooth enamel demineralization. Objective: To measure Vickers hardness of human enamel exposed to sports drinks. METHODS: Human molars were used to collect the enamel samples. Each sample had a test surface (exposed to the drinks) and a control surface (unexposed). The samples were exposed to isotonic drinks Gatorade and Powerade, and to maltodextrin drinks Malto Advanced and Malto Active, for 10 minutes every 12 hours over 30 days. The Vickers microhardness test was conducted with three indentations on each surface. The mean of the indentations within each group was considered in the statistical analysis. Sports drinks variables were analyzed with ANOVA/Tukey (p≤0.01). The independent t-test was used in the comparison between the control and test surfaces of each drink (p ≤ 0.05). RESULTS: Enamel exposure to Gatorade (p = 0.000) Malto Advanced (p = 0.000) and Malto Active (p = 0.000) was seen to significantly reduce microhardness, while the isotonic drink Powerade had no significant effect on enamel (p = 0.248). CONCLUSION: It was concluded that with the exception of the isotonic drink Powerade, all the sports drinks tested caused a reduction in the microhardness of human enamel. Evidence Level III; Therapeutic studies - Investigating the Results of Treatment.

INTRODUÇÃO: O baixo pH de bebidas esportivas pode promover perda mineral do esmalte dental. OBJETIVO: Avaliar a microdureza Vickers do esmalte humano exposto a bebidas esportivas. MÉTODOS: Dentes molares humanos foram usados para coletar as amostras de esmalte. Cada amostra apresentou uma superfície de teste (exposta às bebidas) e uma superfície de controle (não exposta). As amostras foram expostas aos isotônicos Gatorade e Powerade e às maltodextrinas Advanced Series e Malto Active durante 10 minutos de 12/12 horas, durante 30 dias. O teste de microdureza Vickers foi realizado com três indentações em cada superfície. Na análise estatística, foi considerada a média das indentações dentro de cada grupo. As variáveis bebidas esportivas foram avaliadas com ANOVA/Tukey (p ≤ 0,01). Na comparação entre a superfície controle e teste de cada bebida foi utilizado o Teste t para amostras independentes (p ≤ 0,05). RESULTADO: Observou-se que a exposição do esmalte a Gatorade (p = 0,000), Malto Advanced (p = 0,000) e Malto Active (p = 0,000) reduz significativamente a microdureza, enquanto que o isotônico Powerade não produziu efeito significativo sobre o esmalte (p = 0,248). CONCLUSÃO: Concluiu-se que com exceção do isotônico Powerade, todas as bebidas esportivas testadas provocaram redução na microdureza do esmalte dental humano. Nível de Evidência III; Estudos terapêuticos ­ investiga o resultado de um tratamento.

INTRODUCCIÓN: El bajo pH de bebidas deportivas puede favorecer la pérdida mineral del esmalte dental. OBJETIVO: Evaluar el esmalte dureza Vickers humano expuesto a las bebidas deportivas. MÉTODOS: Se utilizaron los dientes molares para la toma de las muestras de esmalte. Cada muestra tenía una superficie de prueba (expuestos a las bebidas) y una superficie de control (no ex-puesta). Las muestras fueron expuestas en isotónica Gatorade y Powerade, y maltodextrinas, y la serie Advanced activo Malto durante 10 minutos 12/12 horas durante 30 días. La prueba de dureza Vickers se realizó con tres muescas en cada superficie. El análisis estadístico fue la media de las muescas dentro de cada grupo. variables de bebidas deportivas se analizaron con ANOVA / Tukey (p≤0,01). La comparación entre la superficie de control y prueba de cada bebida se utilizó la prueba t para muestras independientes (p ≤ 0,05). RESULTADOS: Se observó que la exposición del esmalte Gatorade (p = 0,000) Malto avanzada (p = 0,000) y Malto activo (p = 0,000) reduce significativamente la dureza, mientras que Powerade isotónica ningún efecto significativo sobre el esmalte (p = 0,248). CONCLUSIÓN: Se concluye que con la excepción de Powerade isotónica, todas las bebidas deportivas probados causó una reducción en la dureza del esmalte humano. Nivel de Evidencia; Estudios terapéuticos - Investigación de los resultados del tratamento.

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.

Food acid content and erosive potential of sugar-free confections.

BACKGROUND: Dental erosion is an increasingly prevalent problem associated with frequent consumption of acidic foods and beverages. The aim of this study was to measure the food acid content and the erosive potential of a variety of sugar-free confections. METHODS: Thirty sugar-free confections were selected and extracts analysed to determine pH, titratable acidity, chemical composition and apparent degree of saturation with respect to apatite. The effect of the sugar-free confections in artificial saliva on human enamel was determined in an in vitro dental erosion assay using change in surface microhardness. RESULTS: The change in surface microhardness was used to categorize the confections as high, moderate or low erosive potential. Seventeen of the 30 sugar-free confections were found to contain high concentrations of food acids, exhibit low pH and high titratable acidity and have high erosive potential. Significant correlations were found between the dental erosive potential (change in enamel surface microhardness) and pH and titratable acidity of the confections. Ten of these high erosive potential confections displayed dental messages on the packaging suggesting they were safe for teeth. CONCLUSIONS: Many sugar-free confections, even some with 'Toothfriendly' messages on the product label, contain high contents of food acids and have erosive potential.

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.

Aplicabilidad del modelo electroquímico al inicio de la caries dental. Estudio in vitro / Applicability of electrochemical model at the onset of tooth decay. An in vitro study

Introducción: Se ha establecido que existen fuerzas eléctricas que tienen la capacidad de dañar la estructura dental generando su descalcificación. El objetivo es demostrar que el modelo electroquímico permite explicar el proceso de disolución del esmalte dental, a través de la aplicación de un potencial constante, a fin de registrar corriente eléctrica, liberación de ion Ca2+ y evaluar daño superficial del esmalte dental. Material y métodos: Estudio in vitro en 32 terceros molares sin caries, divididos aleatoriamente en dos grupos sumergidos en solución tampón láctico-lactato. Grupo 1, sometido a potencial de +1,5 V y grupo 2, se dejó evolucionar espontáneamente en el tiempo. Se cuantificó la concentración de Calcio (Ca2+) liberado (mg), a través de un espectrofotómetro de absorción atómica para establecer la concentración media por grupo. Se compararon las medianas mediante el test estadístico Wilcoxon Mann-Whitney usando el programa Stata v.11.2. Además, se realizó evaluación del daño superficial del esmalte dental por técnica de microscopía óptica y electrónica. Resultados: Se registraron corrientes no nulas en todos los dientes sometidos a potencial +1,5 V. La liberación de Ca2+ entre grupos arrojó mayor liberación mediana de Ca2+ en el grupo electrólisis (12,3 [RIC= 4,5-18,2] vs. 6,5 [RIC= 3,7-15,4]) y al observar bajo lupa estereoscópica y microscopio electrónico de barrido, se visualiza una mayor destrucción en el grupo 1. Discusión: Los resultados permiten verificar la hipótesis en cuanto a haber encontrado evidencia empírica respecto al comportamiento electroquímico del proceso de degradación del esmalte dental (AU)

Introduction: It has been established that there are electrical forces that have the capacity to damage the tooth structure generating decalcification. The aim is to demonstrate that the electrochemical model can explained the dissolution of tooth enamel, through the application of a constant potential, in order to register electric current, liberation from Ca2+ and to evaluate surface damage tooth enamel. Material and method: In vitro study on 32 third molars without caries, randomly divided into two groups immersed in a buffer of lactic-lactate solution. Group 1 underwent +1.5 V potential and Group 2 was allowed to evolve spontaneously over time. Ca2+ released (mg) was quantified through an atomic absorption spectrophotometer to set the average concentration per group. Means were compared using Wilcoxon statistical test Mann-Whitney using the Stata v.11.2 program. Also an evaluation of surface damage tooth enamel technique optical and electron microscopy was performed. Results: We recorded non-zero current on all teeth undergoing potential +1.5 V. The release of Ca2+ between groups showed higher median liberation from Ca2+ in the Electrolysis group (12.3 [IQR = 4.5 to 18 2] vs. 6.5 [IQR= 3.7 to 15.4]) and observed under stereomicroscope and scanning electron microscope, further destruction is displayed in group 1. Discussion: The results allow to bear out the hypothesis, it has been found an empirical evidence regarding the electrochemical behavior of the degradation process of tooth enamel (AU)

Comparative Quantitative Assessments of Salivary Ion Activity Product for Hydroxyapatite and Buffering Capacity in Children with Different Caries Experience.

AIM: If a relation exists between salivary IPHA, buffer capacity and caries experience, then this relationship could be used as screening chair side test for caries risk assessment. STUDY DESIGN: One hundred ninety seven children aged 4 to 6 years were examined. Data was collected by interview and clinical examination. They were divided into low, moderate and high caries experience group of 20 children each. Two ml of each sample was used to measure the pH value with pH meter. Regarding the buffering capacity, freshly prepared hydrochloric acid (HCl) was titrated into saliva and pH was recorded. The collected saliva samples were sent to Laboratory for measurement of calcium and phosphorus. IPHA was calculated and the negative logarithms of IPHA were used to determine the enamel solubility. The correlation between salivary IPHA, buffering capacity and caries experience were evaluated. RESULTS: There was a significant relation between pH, log IPHA and dental caries experience, it could be considered as a predictor of dental caries. CONCLUSION: pH measurement after HCl titration in saliva could be used as chair side screening test for the assessment of caries risk.

Effect of long term application of toothpaste Apadent Total Care Medical nano-hydroxyapatite. / Otsenka effektivnosti dlitel'nogo primeneniya zubnoi pasty Apadent Total Care, soderzhashchei Meditsinskii nano-gidroksiapatit.

The aim of the study was to evaluate the efficacy of toothpaste «Apadent Total Care¼ containing nanocalciumhydroxyapatite and its influence on caries resistance of tooth enamel and teeth sensitivity. The study involved 30 people: 15 patients aged 17-25 years and 15 aged 35-44 years. Study participants used «Apadent Total Care¼ toothpaste with nanocalciumhydroxyapatite. To evaluate the effectiveness of toothpastes clinical assessment of enamel remineralization rate was carried out, as well as the dynamics of enamel acid resistance and teeth sensitivity (Shiff index). Clinical evaluation of tooth enamel before the procedure and after 3 months of use of toothpaste with nanohydroxyapatite showed the improvement of all indices. Time for complete remineralisation of enamel in both groups did not exceed 3 days. Acid resistance of tooth enamel increased by 1.65 in group I and 1,75 in group II. The Schiff index after 3 months of using «Apadent¼ toothpaste also decreased in both groups.

Relationship between analysis of laser speckle image and Knoop hardness on softening enamel.

BACKGROUND: In this study is presented the correlation between laser speckle images and enamel hardness loss. METHODS: In order to shift the enamel hardness, a dental demineralization model was applied to 32 samples of vestibular bovine teeth. After they were cleaned, cut and polished, the samples were divided into 4 groups and immersed in 30ml of a cola-based soft drink for 10, 20, 30 and 40min twice a day for 7 consecutive days with half the surface protected by two layers of nail polish. Each sample was analyzed by Knoop hardness and laser speckle imaging. RESULTS: Pearson's correlation analysis demonstrated that the laser speckle image technique presents a strong correlation with the hardness loss of the enamel (r=0.7085, p<0.0001). This finding is corroborated by Blend & Altman analysis, in which the data presented a constant behavior throughout the whole interval. For both analyses, more than 95% of the data is within the confidence interval, as expected. CONCLUSION: This work demonstrates, for the first time to our knowledge, an empirical model for correlating laser speckle images with the loss of tooth enamel hardness.

Morphological Evaluation of the Adhesive/Enamel interfaces of Two-step Self-etching Adhesives and Multimode One-bottle Self-etching Adhesives.

PURPOSE: To evaluate the acid-base resistant zone (ABRZ) at the adhesive/enamel interface of self-etching adhesives with or without prior phosphoric acid etching. MATERIALS AND METHODS: Four adhesives were used in 8 groups: Clearfil SE Bond (SEB), Optibond XTR (XTR), Scotchbond Universal Adhesive (SBU), and Clearfil BOND SE ONE (ONE) without prior phosphoric-acid etching, and each adhesive with phosphoric acid etching for 10 s (P-SEB, P-XTR, P-SBU and P-ONE, respectively). After application of self-etching adhesives on ground enamel surfaces of human teeth, a flowable composite was placed. For observation of the acid-base resistant zone (ABRZ), the bonded interface was exposed to demineralizing solution (pH 4.5) for 4.5 h, followed by 5% NaOCl with ultrasonication for 20 min. After the acid-base challenge, morphological attributes of the interface were observed using SEM. RESULTS: ABRZ formation was confirmed in all groups. The funnel-shaped erosion beneath the interface was present in SBU and ONE, where nearly 10 to 15 µm of enamel was dissolved. With phosphoric acid etching, the ABRZs were obviously thicker compared with no phosphoric acid etching. CONCLUSION: Enamel beneath the bonding interface was more susceptible to acid dissolution in SBU and ONE. In the case of the one-bottle self-etching adhesives and universal adhesives that intrinsically have higher pH values, enamel etching should be recommended to improve the interfacial quality.

Impact of Acquired Pellicle Modification on Adhesion of Early Colonizers.

New preventive approaches against dental erosion caused by acidic drinks and beverages include fortification of beverages with natural polymers. We have shown that the mixture of casein and mucin significantly improved the erosion-inhibiting properties of the human pellicle layer. This study aimed to investigate the effect of pellicle modification by casein, mucin and a casein-mucin mixture on the adhesion of early bacterial colonizers. Test specimens of human tooth enamel were prepared, covered with saliva and coated with 0.5% aqueous (aq.) casein, 0.27% aq. mucin or with 0.5% aq. casein-0.27% aq. mucin, after which the adhesion of Streptococcus gordonii, Streptococcus oralis, and Actinomyces odontolyticus was measured after incubation for 30 min and 2 h. log10 colony-forming units were compared by nonparametric tests. All three bacterial strains adhered in higher number to pellicle-coated enamel than to native enamel. The protein modifications of pellicle all decreased the counts of adhering bacteria up to 0.34 log10/mm2, the most efficient being the casein-mucin mixture. In addition to the recently shown erosion-reducing effect by casein-mucin, modification of the pellicle may inhibit bacterial adherence compared to untreated human pellicle.

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.

The future of fluorides and other protective agents in erosion prevention.

The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H(+) at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects.

Weaker dental enamel explains dental decay.

Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

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.