Saliva Decreases Sucrose-Induced Cariogenicity in an Experimental Biological Caries Model.

OBJECTIVE: Whether a minimum quantity of saliva inhibit the caries process remains uncertain. This study aimed to investigate the impact of saliva dilutions on an in vitro caries model using Streptococcus mutans (S. mutans) biofilms. METHODS: S. mutans biofilms were cultivated on enamel and root dentin slabs, in culture media containing different proportions of saliva (v/v): 0%, 5%, 10%, 25%, 50%, 75%, and 100% saliva, and exposed to a 10% sucrose solution (5 min, 3x/day), with appropriate controls. After 5 (enamel) and 4 (dentin) days, demineralization, biomass, viable bacteria, and polysaccharide formation were analyzed. The acidogenicity of the spent media was monitored overtime. Each assay was performed in triplicate across two independent experiments (n = 6). RESULTS: In both enamel and dentin, an inverse relationship was observed between acidogenicity, demineralization, and the proportion of saliva. Even small quantities of saliva incorporated into the media led to a noticeable reduction in enamel and dentin demineralization. Saliva presence resulted in significant reductions in biomass, viable S. mutans cells, and polysaccharides, with the effects being concentration-dependent for both tissues. CONCLUSIONS: High quantities of saliva can almost completely inhibit sucrose-induced cariogenicity, while even small amounts exhibit a dose-dependent caries-protective effect.

Effect of Casein Phosphopeptide-Amorphous Calcium Phosphate Added to Milk, Chewing Gum, and Candy on Dental Caries: A Systematic Review.

Casein is one of the most studied proteins with activity against dental caries. In particular, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has shown promising remineralizing properties. In vivo evidence on the anticaries potential of CPP-ACP added to foodstuffs is elusive, nonetheless. Hence, this systematic review aimed at determining whether the use of CPP-ACP added to foodstuffs has a remineralizing or inhibitory action on dental demineralization either in vivo or in situ. The review protocol followed the PRISMA-P criteria and was registered in PROSPERO. PubMed, Scopus, and Web of Science databases were searched using predefined criteria, based on the PICO question: Is there an effect on dental caries upon adding CPP-ACP to milk, chewing gums, or candies? No year or language limits were applied. Article selection and data extraction were carried out independently by 2 investigators. Two hundred ten titles were examined, 23 were selected for full-text review, and 16 studies were included (2 in vivo and 14 in situ). CPP-ACP was added to candy in 2 studies, to milk in 2 studies, and to chewing gum in 12 studies. The main outcomes included enamel remineralization and activity against dental biofilm. The overall quality of the evidence was classified as moderate. The available evidence suggests that CPP-ACP added to milk, chewing gum, or candy has a potential remineralizing activity on tooth enamel, with some additional antibacterial activity on the dental biofilm. Further clinical studies are needed to verify if this effect is clinically significant in reducing the caries lesion incidence or to revert the demineralizing process.

Understanding dental caries as a non-communicable and behavioral disease: Management implications.

New paradigms in caries conceptualization have emerged during the last decades, leading to intense debate and discussion on how to approach the disease, both from a preventive and a therapeutic perspective. Among many new ideas, research discoveries and technologies, one major concept can be highlighted that created a deep frontier between the old and the new paradigm in caries conceptualization; the non-communicable nature of the disease, firmly associated with behaviors and lifestyles. This article synthetizes the conceptual construction of dental caries as a non-communicable disease (NCD) based on the current evidence and discusses the appropriate management of the disease in this context. Dental caries has shifted from being considered transmissible and infectious to an ecological and non-communicable disease. Environmental factors such as frequent sugars intake, disrupt the symbiosis of the dental biofilm leading to a dysbiosis, which favors caries lesion initiation and progression. As an NCD, dental caries shares characteristics with other NCDs such as cardiovascular and chronic respiratory diseases, cancer and diabetes, including long duration and slow progression, not being transmissible from person-to-person, being strongly related to modifiable behavioral risk factors, and affecting preferentially disadvantaged populations with a strong inequality gradient. Given the high prevalence of dental caries, and its consequences on people's health and quality of life, a recognizable conceptual view of caries as a NCD is required to target an effective management. Current understanding of dental caries supports prevention through acting on the modifiable risk factors (behaviors) and involves management based on an interdisciplinary approach. Communicating these modern concepts among researchers, clinicians and policymakers is needed to decrease the global high burden of the disease.

Fluoride concentration in teas derived from Camellia Sinensis produced in Argentina.

To evaluate the fluoride concentration and pH of tea derived from Camellia sinensis produced and commercialized in Argentina. Forty-eight varieties of tea (black (n = 16), green (n = 21), red (n = 7), and white (n = 4)) commercialized in the form of leaves or tea bags were acquired. One bag or 2.0 ± 0.05 g of each product was infused for 5 min in 200 mL of distilled boiled water. The F- concentration was determined using an ion-selective electrode and pH was measured using a pH meter. The found fluoride concentrations ranged from 0.1 to 9.7 µg/mL and the pH ranged from 2.7 to 5.1. A higher fluoride concentration was observed in the leaves group (2.75 ± 2.65 µg/mL) compared to tea bags (1.10 ± 0.82 µg/mL) (p < 0.05). Regarding the type of tea, green and black tea were richer in F- than red and white tea. Fluoride and pH appeared not to be correlated (Pearson test). All the studied tea samples presented fluoride concentrations greater than the threshold recommended for drinking water. The pH proved to be low, which could be a risk for erosive tooth wear.

Effect of pH and titratable acidity on enamel and dentine erosion.

OBJECTIVES: The relative effect of pH and titratable acidity on tooth erosion remains unclear. We determined the effect of both properties on in vivo salivary pH recovery and on enamel and dentine early erosion in situ. METHODS: Solutions simulating acidic beverages with different pHs (2.5 or 3.5) and titratable acidities (0, 25, or 100 mM citric acid) were tested. In an in vivo study (n = 20 participants), the salivary pH was determined before, during, and up to 2 min after exposure to the tested solutions. In situ, 12 participants exposed enamel and root dentine slabs to the tested solutions simulating a beverage consumption; early erosion was assessed by percentage of surface hardness loss (%SHL). Groups were compared by ANOVA (p < 0.05). RESULTS: Saliva pH was lower after exposure to solutions at pH 2.5, irrespective of titratable acidity; pH recovery took longer for solutions with higher titratable acidities, irrespective of their pHs. In situ, the highest %SHL was observed for the solution with lower pH and higher titratable acidities. The addition of citric acid increased the %SHL by 2.5-3 times in enamel, and at least 5 times in dentine. CONCLUSIONS: Both pH and titratable acidity may play a role on the erosive potential of acidic beverages. CLINICAL RELEVANCE: Acidic beverages with lower pHs promote erosion by an initial acid etching of the surface; those with a higher titratable acidity slow down the salivary pH recovery. Both properties contribute to the overall erosive potential.

Unsweetened and sucrose-sweetened black and green tea modifies the architecture of in vitro oral biofilms.

OBJECTIVE: It is unclear whether tea infusions with or without sucrose supplementation alter oral biofilm development, so we evaluated the effect of unsweetened and sucrose-sweetened black and green tea infusions on in vitro saliva-derived biofilms. DESIGN: Biofilms were developed from human saliva for 20 h in cell-free 25% human saliva within static glass-bottom microplates. During biofilm development, biofilms were treated with either (i) unsweetened black tea, (ii) unsweetened green tea, (iii) 10% sucrose-sweetened black tea, (iv) 10% sucrose-sweetened green tea (v) deionized water (negative control), or (vi) 10% sucrose (positive control). Biofilms were incubated at 37 °C in 5% CO2. After 20 h of development, biofilms were imaged using a CLSM, and biofilm architecture and viability were evaluated. RESULTS: All the tea infusions reduced biofilm biomass and altered some other biofilm architectural outcomes (e.g., biofilm surface area) compared to the control groups. Statistically significant differences in biofilm biomass, number of objects, surface area, and convex-hull porosity were observed between biofilms treated with green and black tea. The addition of sugar to tea did not significantly modify the ability of tea to alter biofilm architecture. Only the treatment of biofilms with unsweetened black tea significantly reduced bacterial viability. CONCLUSIONS: While both teas reduced biofilm biomass and altered biofilm architecture, black tea had an enhanced effect that may relate to this tea's observed antimicrobial activity. The addition of sucrose to tea infusions did not appear to reduce the impact of either tea in modifying oral biofilm architecture.

¿Cómo Intervenir el Proceso de Caries en Adultos? Adaptación del Consenso de ORCA/EFCD/DGZ / How to Intervene the Caries Process in Adults? Adaptation of the ORCA/EFCD/DGZ Consensus

RESUMEN: El manejo terapéutico de lesiones de caries primarias y secundarias concentra gran parte del quehacer de los dentistas en el mundo. Recientes cambios en la concepción de la enfermedad de caries llevaron a un panel de expertos de la Organización Europea para la Investigación en Caries (ORCA), la Federación Europea de Odontología Conservadora (EFCD) y la Federación Alemana de Odontología Conservadora (DGZ) a analizar la evidencia y consensuar recomendaciones sobre manejo de caries en adultos. Mediante una reunión en Berlín, Alemania en 2019 y con metodología e-Delphi, los expertos analizaron la evidencia y propusieron recomendaciones clínicas. El propósito de este artículo es presentar una adaptación idiomática de las principales recomendaciones, que incluyen terapias no invasivas (higiene, uso de fluoruros y control de dieta), terapias microinvasiva (sellantes e infiltrantes), terapias necesariamente invasivas y la reparación de restauraciones. Todas las recomendaciones se basan en un enfoque mínimamente invasivo, con un adecuado manejo restaurador. Los dentistas de países hispanoparlantes podrán encontrar recomendaciones basadas en evidencia, provenientes de un consenso de expertos a nivel global, que orienten sus decisiones clínicas, apoyándose en los principios de la odontología de mínima intervención.

ABSTRACT: Therapeutic management of primary and secondary caries lesions concentrates much of the work of dentists throughout the world. Recent changes in caries disease conception and therapeutic management led a panel of experts from the European Organisation for Caries Research (ORCA), the European Federation for Conservative Dentistry (EFCD) and the German Federation for Conservative Dentistry (DGZ) to analyze the evidence and reach consensus on recommendations for caries management in adults. Through a meeting held in Berlin, Germany in 2019 and using an e-Delphi methodology, the experts analyzed the evidence and proposed clinical recommendations. The purpose of this article is to present an idiomatic adaptation to Spanish of the main recommendations, which include non-invasive therapies (hygiene, use of fluoride and diet control), microinvasive therapies (sealants and infiltrants), invasive therapies and repair of restorations. All recommendations are based on a minimally invasive dentistry approach, with a technically adequate restorative management. Spanish-speaking dentists may use these consensus recommendations to guide their clinical decisions, based on the most recent evidence and experts opinions, under the principles of minimal intervention dentistry.

COVID-19 pandemic accelerated virtual transformation in dental education: a multicenter review of remote teaching and teledentistry / Transformação virtual acelerada pela pandemia de COVID-19 na educação odontológica: uma revisão multicêntrica do ensino à distância e da teleodontologia

ABSTRACT Although prior to the pandemic there was some resistance to the virtualization of dental education, the COVID-19 pandemic is providing us a unique opportunity to overcome several barriers that previously blocked the adoption of remote teaching and teledentistry. Thanks to the extended availability of telecommunications, digital technologies, and platforms, remote education and teledentistry appear to be the preferred choice to maintain dental education and patient care active under this pandemic, without contamination risks. In this paper, we review valid remote education strategies and possible alternatives useful in virtual transformation in dental education. Furthermore, the role of teledentistry and its advantages and challenges are also revised. Under the current pandemic context, as dental educators, we are called to be creative and flexible. Every dental school should adapt and use remote education as much as possible until clinical attention can be readopted. The evidence presented in this review supports our position that under this pandemic, remote education and telemedicine/teledentistry may be "the virtual convenient solution", to adapt and improve the hitherto classic way of teaching dentistry through tele-education.

RESUMO Embora antes da pandemia houvesse alguma resistência à virtualização da educação odontológica, a pandemia COVID-19 está nos fornecendo uma oportunidade única de superar várias barreiras que anteriormente bloqueavam a adoção do ensino à distância e teledontologia. Graças à ampla disponibilidade de telecomunicações, tecnologias digitais e plataformas, a educação à distância e a teledontologia parecem ser a escolha preferida para manter a educação odontológica e o atendimento ativo aos pacientes durante a pandemia, sem riscos de contaminação. Neste artigo, revisamos estratégias válidas de educação a distância e possíveis alternativas úteis na transformação virtual na educação odontológica. Além disso, o papel do teleodontologia e suas vantagens, assim como também os desafios. No atual contexto pandêmico, como educadores odontológicos, somos chamados a ser criativos e flexíveis. Cada escola de odontologia deve se adaptar e usar a educação à distância, tanto quanto possível, até que a atenção clínica possa ser readotada. As evidências apresentadas nesta revisão corroboram nossa posição de que, sob esta pandemia, a educação a distância e a telemedicina / teleodontologia podem ser "a solução virtual conveniente", para adaptar e aprimorar a forma até então clássica de ensino de odontologia, agora por meio da teleducação.

Minimum intervention dentistry in the US: an update from a cariology perspective.

Despite evidence strongly supporting use of non-invasive or minimally invasive procedures in caries management, there is still a large gap between evidence-based recommendations and application of these concepts in practice, with the practice of dentistry still largely dominated by invasive procedures in the US. This paper describes efforts in education and clinical practice in the US in the last decade to promote evidence-based cariology strategies, which support a minimum intervention dentistry (MID) philosophy. These include, for example: a competency-based core cariology curriculum framework which has been developed and disseminated. National education accreditation standards supporting caries management are likely to soon be changed to support assessment of best evidence in cariology. There are several ongoing efforts by organised dentistry and other groups involving dental educators, researchers and clinical practitioners to promote cariology concepts in practice, such as the development of evidence-based clinical practice guidelines for caries management by the American Dental Association. Within each of these strategies there are challenges, but also opportunities to expand the implementation of MID in the US, which create optimism for future improvements over time.

Strategies and operational procedures in oral radiology to mitigate potential SARS-CoV-2 transmission / Estrategias y procedimientos operacionales en Radiología Oral para mitigar transmisión de SARS-CoV-2

SUMMARY Coronavirus disease (COVID-19) is highly transmissible through respiratory droplets, saliva, and aerosol particles. Infection can lead to severe acute respiratory syndrome and trigger multi-organ failure and death. Most clinical dental procedures involve contact with saliva or the generation of aerosols with saliva and blood. These airborne particles increase the risk of transmission by COVID-19 between dentists and patients. Thus, dentistry must adopt procedures to reduce transmission during dental procedures. Although these strategies may not be directly applicable to all institutions due to cultural, social, geographical, and economic differences, the underlying principles and implemented strategies remain relevant and can be adopted or modified by the institutions dealing with the current COVID-19 outbreak. The purpose of this article is to discuss one of the principal sources of COVID-19 transmission: saliva, the biofluid most frequently handled in a radiology environment. The authors also recommend strategies and operational procedures to decrease the spread of COVID-19 in a radiological routine.

RESUMEN La enfermedad por coronavirus (COVID-19) se transmite fácilmente a través de gotitas respiratorias, saliva y partículas de aerosol. La infección puede desencadenar un síndrome respiratorio agudo severo, insuficiencia multiorgánica y, en algunos casos, la muerte. Los procedimientos clínicos dentales determinan el contacto con saliva o la generación de aerosoles con saliva y sangre, lo que implica un alto riesgo de transmisión por COVID-19 entre odontólogos y pacientes. Por ello, la práctica odontologica debe adoptar medidas para detener la propagación durante los procedimientos dentales. En este artículo se revisan las estrategias para mitigar el riesgo de transmisión de COVID-19. Si bien estas estrategias pueden no ser directamente aplicables a todas las instituciones debido a diferencias culturales, sociales, geográficas y económicas inherentes, los principios subyacentes y las estrategias implementadas siguen siendo relevantes y pueden ser adoptados o modificados por las instituciones que se ocupan del brote actual de COVID-19. El propósito de este artículo es discutir una de las principales fuentes de transmisión de COVID-19: la saliva, el biofluido que se maneja con mayor frecuencia en un entorno radiológico. Los autores también recomiendan estrategias y procedimientos operativos para disminuir la propagación de COVID-19 en una rutina radiológica.

Conceptualization of dental caries by dental students is related to their preventive oral care routine.

OBJECTIVE: Whether the understanding of dental caries influences how future dentists manage the disease themselves has not been previously studied. Thus, this study evaluated whether the conceptualization (understanding) of dental caries by dental students is related to their own preventive oral care routine. METHODS: Dental students at a U.S. dental school (n = 517) were invited to voluntarily respond to an anonymous electronic survey in spring 2018. Demographic characteristics, caries conceptualization (CC), dental care habits, and self-caries risk determination were asked. Discursive responses to CC were analyzed by content analysis technique, and categories [c] were created. Chi-square and Fisher's exact tests were used for analysis. RESULTS: Overall response rate was 54.5% (n = 282, 48.2% female). Three researchers independently analyzed discursive answers and classified them into 1 of 6 caries concept categories [c]: [c1] only signs of the disease (10.3%), [c2] bacterial disease-not specifying bacterial metabolism (38.3%), [c3] bacterial byproducts-not specifying substrate (13.8%), [c4] biological or multifactorial concept (24.8%), [c5] comprehensive multifactorial disease (8.2%), or [c6] other (4.6%). Only 33% completely defined dental caries according to the modern understanding of the disease (c4-c5). Statistical differences were found between: CC and diet modification, CC and rinsing after brushing, year of school (YS) and self-determined caries-risk, YS and brushing at school, and YS and rinsing after brushing (P < 0.05). CONCLUSION: Our data suggest that the students' understanding of the disease can influence how they will manage the disease in terms of diet modification and behavior after brushing. Moreover, self-caries risk determination influenced students' brushing behavior.

Commercial Silver Diamine Fluoride (SDF) Products on Caries Lesion Progression in Primary Enamel: An In Vitro Study.

Purpose: Evidence has shown that silver diamine fluoride (SDF) at 30-38% has the potential to control and revert caries lesions. However, SDF can be found at lower concentrations on the market. In this study, we evaluated the effect of different commercially available SDF products on the progression of non-cavitated caries lesion in primary teeth assessed by a pH-cycling model. Materials and Methods: Subsuperficial caries lesions were formed in primary teeth using a demineralising solution for 96 h. Demineralised samples were randomly allocated to the following groups (n = 12/group): (G1) Negative Control, deionised water; (G2) Cariostatic, Inodon; 10%* SDF; (G3) Cariestop, Biodynamics, 12%* SDF; (G4) Cariostal, Iodontec, 16%* SDF; (G5) Cariestop, Biodynamics, 30%* SDF (*concentrations declared in the label). Products were applied according to the manufacturer's recommendation and reapplied after 7 days. Samples were exposed to a pH-cycling model for 14 days. After the cycle was completed, samples were sectioned, analysed by polarised light microscopy, and lesion depth was estimated as indicator of caries lesion progression. Groups were compared by multiple comparisons test (p < 0.05). Results: The negative control group exhibited the greatest lesion depth. All SDF products reduced the caries lesions depth and differed from the negative control. It was a trend observed (G1>G2>G3>G4), but no statistical differences among G3, and G5, and between G4 and G5 were observed for lesion depth. Conclusion: The tested SDF products reduced the depth of non-cavitated carious lesions in primary enamel. Although SDF products with declared concentrations between 12% and 30% (G3, G4, and G5) demonstrated a similar lesion depth in primary enamel, the effect of the concentration remains unclear.

Effect of 5,000 ppm Fluoride Dentifrice or 1,100 ppm Fluoride Dentifrice Combined with Acidulated Phosphate Fluoride on Caries Lesion Inhibition and Repair.

High fluoride dentifrice (FD; 5,000 ppm F) has been recommended to arrest root dentine lesions and to control enamel caries in high-risk patients. Also, standard FD (1,100 ppm F) in combination with professional fluoride application has been recommended to control dentine caries, but the effect of this combination on enamel has been considered modest. Considering the lack of evaluation comparing the use of 5,000 ppm FD (5,000-FD) versus acidulated phosphate fluoride (APF) application combined with 1,100 ppm FD (1,100-FD) on the inhibition and repair of caries lesions in both enamel and dentine, we conducted this in situ, double-blind, crossover study of 3 phases of 14 days. In each phase, 18 volunteers wore palatal appliances containing enamel and root dentine specimens, either sound or carious, to evaluate the effect of the treatments on the inhibition or repair of caries lesions, respectively. The treatments were non-FD (negative control), 5,000-FD, or 1 APF gel application on dental specimens combined with 1,100-FD used twice per day (APF + 1,100-FD). The reduction of demineralization and enhancement of remineralization were assessed by surface and cross-sectional hardness. Fluoride concentration was determined on dental specimens and on the formed biofilm. For enamel, APF + 1,100-FD and 5,000-FD did not differ regarding the inhibition of demineralization and repair of caries lesions. However, for dentine the difference between these treatments was inconclusive because while APF + 1,100-FD was more effective than 5,000-FD in caries lesion reduction and repair, 5,000-FD was more effective than APF + 1,100-FD in the reduction of surface demineralization. Therefore, the findings show that the combination of APF + 1,100-FD is as effective as 5,000-FD in enamel inhibition of demineralization and enhancement of remineralization.

Stability of chemically available fluoride in Chilean toothpastes.

BACKGROUND: Storage time may reduce the amount of soluble fluoride (F) in toothpastes. Although we previously studied the type and concentration of F in fresh samples of commercial Chilean toothpastes, their stability was not determined. AIM: To evaluate the stability of soluble F in Chilean toothpastes after 1 year of storage. DESIGN: All the toothpastes (n = 30) previously used were re-analyzed after 1 year of storage time at room temperature (±22°C). Total F (TF = soluble F + insoluble F) and total soluble F (TSF = F ion + MFP ion) were assessed using an ion-specific electrode, through a validated methodology. Data were expressed in ppm of F (mg F/kg). RESULTS: Mean (±SD; n = 30) TF and TSF concentrations after storage were 1049 ± 427 and 987 ± 411 ppm F, respectively. Five toothpastes showed between 30% and 50% of insoluble F, four of them formulated with MFP/calcium-based abrasive. In two products, there was a reduction in TSF below the evidence-based anticaries effectiveness threshold of 1000 ppm F. CONCLUSIONS: Although most of the toothpastes tested kept their original TSF content after 1 year of storage, some products evidenced an important reduction, which may compromise their anticaries efficacy. Reductions in TSF may be explained by an incorrect F salt-abrasive formulation.

Effect of Fluoride-Containing Toothpastes on Enamel Demineralization and Streptococcus mutans Biofilm Architecture.

This study aimed to explore the effect of fluoridated toothpastes on biofilm architecture and enamel demineralization in an in vitro biofilm model. Streptococcus mutans was grown on enamel and treated with slurries of commercial toothpastes, containing SnF2 or NaF. Water and chlorhexidine were used as negative and positive controls, respectively. The developed biofilms were imaged and enamel demineralization was measured. SnF2 and NaF toothpaste treatments significantly reduced enamel demineralization, but SnF2 toothpaste was more effective. Only SnF2 toothpaste and chlorhexidine treatments caused reductions on biofilm mass and thickness. In conclusion, this biofilm model was able to differentiate the effects of the SnF2 and NaF toothpastes on biofilm architecture and enamel demineralization.

Validation of a Cariogenic Biofilm Model to Evaluate the Effect of Fluoride on Enamel and Root Dentine Demineralization.

Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8×/day to 10% sucrose and treated 2×/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2×/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (%SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and %SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.