Three-Dimensional Surface Texture Characterization of In Situ Simulated Erosive Tooth Wear.

This in situ erosive tooth wear (ETW) study tested enamel 3-dimensional (3D) surface texture outcomes for the detection and differentiation of ETW lesions simulated in clinically relevant conditions. Twenty participants enrolled in this 3-arm crossover intraoral ETW simulation and wore their own partial denture for 14 d holding 2 human enamel specimens (per arm). In each arm, participants were assigned to 1 of 3 different dental erosion protocols: severe (lemon juice/pH 2.5), moderate (grapefruit juice/pH 3.5), and no erosion (bottled drinking water, control). Enamel specimens were evaluated by white-light scanning confocal profilometry for 3D surface texture and surface loss (ETW model validation). Individual point clouds were analyzed using standard dental microwear texture characterization protocols for surface roughness and anisotropy. Fractal complexity (Asfc), texture aspect ratio (Str), and arithmetical mean height (Sa) values were generated at baseline, 7 d, and 14 d. Data were analyzed by analysis of variance models suitable for the crossover design with repeated measurements, and correlation coefficients were used to examine the relationship between outcomes. Asfc and Sa differentiated ETW severity (no erosion < moderate < severe, P < 0.001) at days 7 and 14. Asfc and Sa were lower at baseline compared to days 7 and 14 (P < 0.001) for moderate and severe challenges. Asfc increased from day 7 to 14 (P = 0.042) for the severe challenge. For Str, ETW severity did not have a significant effect overall (P = 0.15). Asfc and Sa were highly positively correlated (r = 0.89, P < 0.001), while Asfc and Sa were not correlated overall with Str (r < 0.1, P ≥ 0.25). Enamel surface loss increased with ETW severity (no erosion < moderate < severe, P < 0.001) at days 7 and 14, validating the ETW simulation model. Complexity (Asfc) and roughness (Sa) outcomes were able to detect and differentiate ETW levels, with Asfc being able to monitor the progression of severe lesions. No clear characterization of ETW lesions could be provided by the anisotropy (Str) parameter.

Randomised study of the effects of fluoride and time on in situ remineralisation of acid-softened enamel.

OBJECTIVES: This single-centre, randomised, crossover study used a short-term in situ dental erosion remineralisation model to explore the remineralisation of acid-softened enamel in the 4-h period immediately following brushing with an anti-erosion, dentin hypersensitivity test dentifrice containing 1150 ppm fluoride (as sodium fluoride [NaF]) or a placebo dentifrice with no fluoride. MATERIALS AND METHODS: Fifty participants wearing a palatal appliance holding surface-softened bovine enamel specimens brushed their natural teeth with their assigned dentifrice. Specimens were removed at 5-, 10-, 15-, 30-, 60-, 120- and 240-min post brushing. Enamel remineralisation effect was evaluated at each timepoint by percent surface microhardness recovery (%SMHR) and enamel fluoride uptake (EFU). After a second in vitro erosive challenge, the percent relative erosion resistance (%RER) was calculated. RESULTS: Statistically significant differences in %SMHR were observed for the test dentifrice compared with the placebo dentifrice from the 60-min timepoint onwards (all p < 0.02; mean difference of 8.66 [95% CI 3.46, 13.87] at 60 min). At each specimen removal time, %RER and EFU were statistically significantly higher for the test dentifrice compared with the placebo dentifrice (p < 0.0001 for all). No treatment-related or serious adverse events were reported. CONCLUSIONS: The NaF-containing anti-erosion, dentin hypersensitivity dentifrice improved remineralisation of acid-softened enamel starting at 60 min of intra-oral exposure. It also improved enamel erosion resistance and fluoride uptake as early as 5 min after exposure to fluoridated dentifrice slurry. CLINICAL RELEVANCE: Brushing with a NaF-containing dentifrice can rapidly improve remineralisation, enamel erosion resistance and fluoride uptake.

Nonrestorative Treatments for Caries: Systematic Review and Network Meta-analysis.

The goal of nonrestorative or non- and microinvasive caries treatment (fluoride- and nonfluoride-based interventions) is to manage the caries disease process at a lesion level and minimize the loss of sound tooth structure. The purpose of this systematic review and network meta-analysis was to summarize the available evidence on nonrestorative treatments for the outcomes of 1) arrest or reversal of noncavitated and cavitated carious lesions on primary and permanent teeth and 2) adverse events. We included parallel and split-mouth randomized controlled trials where patients were followed for any length of time. Studies were identified with MEDLINE and Embase via Ovid, Cochrane CENTRAL, and Cochrane Database of Systematic Reviews. Pairs of reviewers independently conducted the selection of studies, data extraction, risk-of-bias assessments, and assessment of the certainty in the evidence with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Data were synthesized with a random effects model and a frequentist approach. Forty-four trials (48 reports) were eligible, which included 7,378 participants and assessed the effect of 22 interventions in arresting or reversing noncavitated or cavitated carious lesions. Four network meta-analyses suggested that sealants + 5% sodium fluoride (NaF) varnish, resin infiltration + 5% NaF varnish, and 5,000-ppm F (1.1% NaF) toothpaste or gel were the most effective for arresting or reversing noncavitated occlusal, approximal, and noncavitated and cavitated root carious lesions on primary and/or permanent teeth, respectively (low- to moderate-certainty evidence). Study-level data indicated that 5% NaF varnish was the most effective for arresting or reversing noncavitated facial/lingual carious lesions (low certainty) and that 38% silver diamine fluoride solution applied biannually was the most effective for arresting advanced cavitated carious lesions on any coronal surface (moderate to high certainty). Preventing the onset of caries is the ultimate goal of a caries management plan. However, if the disease is present, there is a variety of effective interventions to treat carious lesions nonrestoratively.

In Situ Study to Confirm the Anticaries Potential of a Sodium Monofluorophosphate Dentifrice Containing Calcium Sodium Phosphosilicate.

OBJECTIVES: A randomized, investigator-blind, five-treatment, crossover, non-inferiority study was conducted to investigate the effect of the addition of calcium sodium phosphosilicate (CSPS), an agent known to relieve dentin hypersensitivity, to a sodium monofluorophosphate (SMFP)-containing dentifrice on the enamel remineralization potential of fluoride (F), as assessed by percentage surface microhardness recovery (%SMHR) and enamel fluoride uptake (EFU) using a standard in situ caries model. METHODS: Seventy-seven subjects wearing bilateral mandibular partial dentures holding partially demineralized bovine enamel specimens 24 hours/day brushed their teeth with their assigned randomized dentifrice containing either 1500 or 0 ppm F with 5% CSPS or 1500, 500, or 0 ppm F with 0% CSPS twice daily for 21 days. The success criterion was to observe a difference in % SMHR between dentifrices containing 1500 ppm F of six units or less in the upper bound of the two-sided 95% confidence interval (CI). RESULTS: Following 21 days of treatment, the upper bound CI of the %SMHR difference between the dentifrices containing 1500 ppm F was 1.66, thus within the non-inferiority limit. No statistically significant differences for %SMHR (p = 0.2601) and EFU (p = 0.2984) were noted between these two dentifrices. CONCLUSIONS: The present in situ caries study provides evidence demonstrating that the addition of the calcium-containing compound CSPS to a 1500 ppm F dentifrice does not interfere with the ability of fluoride to remineralize surface-softened enamel; i.e., CSPS neither impairs nor improves the potential cariostatic value of SMFP dentifrice.

Effect of toothbrushing duration and dentifrice quantity on enamel remineralisation: An in situ randomized clinical trial.

OBJECTIVES: The influence of toothbrushing duration and dentifrice quantity on fluoride efficacy against dental caries is poorly understood. This study investigated effects of these two oral hygiene factors on enamel remineralisation (measured as surface microhardness recovery [SMHR]), enamel fluoride uptake (EFU), and net acid resistance (NAR) post-remineralisation in a randomized clinical study using an in situ caries model. METHODS: Subjects (n=63) wore their partial dentures holding partially demineralised human enamel specimens and brushed twice-daily for two weeks, following each of five regimens: brushing for 120 or 45s with 1.5g of 1150ppm F (as NaF) dentifrice; for 120 or 45s with 0.5g of this dentifrice; and for 120s with 1.5g of 250ppm F (NaF) dentifrice. RESULTS: Comparing brushing for 120s against brushing for 45s, SMHR and EFU increased by 20.0% and 26.9% respectively when 1.5g dentifrice was used; and by 22.8% and 19.9% respectively when 0.5g dentifrice was used. Comparing brushing with 1.5g against brushing with 0.5g dentifrice, SMHR and EFU increased by 35.3% and 51.3% respectively when brushing for 120s, and by 38.4% and 43.0% respectively when brushing for 45s. Increasing brushing duration and dentifrice quantity also increased the NAR value. The effects of these two oral hygiene factors on SMHR, EFU, and NAR were statistically significant (p<0.05 in all cases). CONCLUSION: Brushing duration and dentifrice quantity have the potential to influence the anti-caries effectiveness of fluoride dentifrices. Study NCT01563172 on ClinicalTrials.gov. CLINICAL SIGNIFICANCE: The effect of two key oral hygiene regimen factors - toothbrushing duration and dentifrice quantity - on fluoride's anticaries effectiveness is unclear. This 2-week home-use in situ remineralisation clinical study showed both these factors can influence fluoride bioactivity, and so can potentially affect fluoride's ability to protect against caries.

The impact of stannous, fluoride ions and its combination on enamel pellicle proteome and dental erosion prevention.

OBJECTIVES: To compare the effects of stannous (Sn) and fluoride (F) ions and their combination on acquired enamel pellicle (AEP) protein composition (proteome experiment), and protection against dental erosion (functional experiment). METHODS: In the proteome experiment, bovine enamel specimens were incubated in whole saliva supernatant for 24h for AEP formation. They were randomly assigned to 4 groups (n=10), according to the rinse treatment: Sn (800ppm/6.7mM, SnCl2), F (225ppm/13mM, NaF), Sn and F combination (Sn+F) and deionized water (DIW, negative control). The specimens were immersed 3× in the test rinses for 2min, 2h apart. Pellicles were collected, digested, and analyzed for protein content using liquid chromatography electrospray ionization tandem mass spectrometry. In the functional experiment, bovine enamel specimens (n=10) were similarly treated for pellicle formation. Then, they were subjected to a five-day erosion cycling model, consisting of 5min erosive challenges (15.6 mM citric acid, pH 2.6, 6×/d) and 2min treatment with the rinses containing Sn, F or Sn+F (3×/d). Between the treatments, all specimens were incubated in whole saliva supernatant. Surface loss was determined by profilometry. RESULTS: Our proteome approach on bovine enamel identified 72 proteins that were common to all groups. AEP of enamel treated with Sn+F demonstrated higher abundance for most of the identified proteins than the other groups. The functional experiment showed reduction of enamel surface loss for Sn+F (89%), Sn (67%) and F (42%) compared to DIW (all significantly different, p<0.05). CONCLUSION: This study highlighted that anti-erosion rinses (e.g. Sn+F) can modify quantitatively and qualitatively the AEP formed on bovine enamel. Moreover, our study demonstrated a combinatory effect that amplified the anti-erosive protection on tooth surface.

Dose-response effect of fluoride dentifrice on remineralisation and further demineralisation of erosive lesions: A randomised in situ clinical study.

OBJECTIVE: The objective was to evaluate the ability of fluoride in a conventional, non-specialised sodium fluoride-silica dentifrice to promote tooth remineralisation and enamel fluoride uptake (EFU), and assess the resistance of the newly formed mineral to attack by dietary acid, across the concentration range used in mass-market dentifrices. METHODS: Subjects wore a palatal appliance containing eight polished bovine enamel specimens, each including an early erosive lesion. In a randomised full-crossover sequence, 62 healthy subjects were treated with dentifrices containing four different fluoride concentrations: no fluoride; 250ppm, 1150ppm and 1426ppm fluoride. At each treatment visit, under supervision, subjects brushed with 1.5g dentifrice and rinsed once while wearing the appliance; the appliance was removed after a 4-h remineralisation period and effects on the enamel specimens determined. The primary efficacy variable was surface microhardness recovery (SMHR); others included EFU, relative erosion resistance (RER) and comparative erosion resistance. RESULTS: Highly significant linear and, with the exception of SMHR, quadratic dose-response relationships were observed between all efficacy variables and fluoride concentration. For SMHR, EFU and RER, values for the different fluoride concentrations were statistically resolved from one another, with the exception of the two highest fluoride concentrations. The degree of remineralisation and the acid resistance of enamel after treatment were closely related to EFU. CONCLUSION: After a single brushing, conventional non-specialised sodium fluoride-silica dentifrices promoted remineralisation of early enamel lesions, and imparted increased acid-resistance to the enamel surface, in a dose-dependent manner at least up to 1500ppm fluoride. CLINICAL SIGNIFICANCE: Enamel erosive tissue loss is an increasing concern, associated with modern diets. This study demonstrated that sodium fluoride, in a conventional non-specialised dentifrice formulation, can promote repair of the earliest stages of enamel erosion after a single application, in a dose-dependent fashion across the fluoride concentration range used in mass-market dentifrices. This study is registered in the GlaxoSmithKline Study Register (ID RH01299), available at: www.gsk-clinicalstudyregister.com/study/RH01299.

A Potential Biofilm Metabolite Signature for Caries Activity - A Pilot Clinical Study.

BACKGROUND: This study's aim was to compare the dental biofilm metabolite-profile of caries-active (N=11) or caries-free (N=4) children by gas chromatography-mass spectrometry (GC/MS) analyses. METHODS: Samples collected after overnight fasting, with or without a previous glucose rinse, were combined for each child based on the caries status of the site, re-suspended in ethanol and analyzed by GC/MS. RESULTS: Biofilm from caries-active sites exhibited a different chromatographic profile compared to caries-free sites. Qualitative and quantitative analysis suggested a special cluster of branched alcohols and esters present at substantially higher intensity in biofilms of caries-active sites. CONCLUSIONS: This pilot study indicates that there are metabolites present in the biofilm which have the potential to provide a characteristic metabolomics signature for caries activity.

Monitoring of sound and carious surfaces under sealants over 44 months.

Although there is strong evidence for the effectiveness of sealants, one major barrier in sealant utilization is the concern of sealing over active caries lesions. This study evaluated detection and monitoring of caries lesions through a clear sealant over 44 mo. Sixty-four 7- to 10-year-old children with at least 2 permanent molars with International Caries Detection and Assessment System (ICDAS) scores 0-4 (and caries less than halfway through the dentin, radiographically) were examined with ICDAS, DIAGNOdent, and quantitative light-induced fluorescence (QLF) before sealant placement and 1, 12, 24, and 44 mo (except QLF) after. Bitewing radiographs were taken yearly. DIAGNOdent and QLF were able to distinguish between baseline ICDAS before and after sealant placement. There was no significant evidence of ICDAS progression at 12 mo, but there was small evidence of minor increases at 24 and 44 mo (14% and 14%, respectively) with only 2% ICDAS ≥ 5. Additionally, there was little evidence of radiographic progression (at 12 mo = 1%, 24 mo = 3%, and 44 mo = 9%). Sealant retention rates were excellent at 12 mo = 89%, 24 mo = 78%, and 44 mo = 70%. The small risk of sealant repair increased significantly as baseline ICDAS, DIAGNOdent, and QLF values increased. However, regardless of lesion severity, sealants were 100% effective at 12 mo and 98% effective over 44 mo in managing occlusal surfaces at ICDAS 0-4 (i.e., only 4 of 228 teeth progressed to ICDAS ≥ 5 associated with sealants in need of repair and none to halfway or more through the dentin, radiographically). This study suggests that occlusal surfaces without frank cavitation (ICDAS 0-4) that are sealed with a clear sealant can be monitored with ICDAS, QLF, or DIAGNOdent, which may aid in predicting the need for sealant repair.

An in situ caries study on the interplay between fluoride dose and concentration in milk.

OBJECTIVES: This randomized, cross-over in situ study investigated the impact of sodium fluoride dose and concentration in milk on caries lesion rehardening, fluoridation and acid resistance. METHODS: Twenty-eight subjects wore two gauze-covered enamel specimens with preformed lesions placed buccally on their mandibular partial dentures for three weeks. Participants used fluoride-free dentifrice throughout the study and consumed once daily one of the five study treatments: no fluoride in 200 ml milk (0F-200), 1.5 or 3 mg fluoride in either 100 (1.5F-100; 3F-100) or 200 ml milk (1.5F-200; 3F-200). After three weeks, specimens were retrieved. Knoop hardness was used to determine rehardening and resistance to a secondary acid challenge. Enamel fluoride uptake (EFU) was determined using a microbiopsy technique. RESULTS: A linear fluoride dose-response was observed for all study variables which exhibited similar overall patterns. All the treatments resulted in rehardening, with 0F-200 inducing the least and 3F-100 the most. Apart from 1.5F-200, all the treatments resulted in statistically significantly more rehardening compared to 0F-200. The fluoride doses delivered in 100 ml provided directionally although not statistically significantly more rehardening than those delivered in 200 ml milk. EFU data exhibited better differentiation between treatments: all fluoridated milk treatments delivered more fluoride to lesions than 0F-200; fluoride in 100 ml demonstrated statistically significantly higher EFU than fluoride in 200 ml milk. Findings for acid resistance were also more discerning than rehardening data. CONCLUSIONS: The present study has provided further evidence for the anti-caries benefits of fluoridated milk. Both fluoride dose and concentration appear to impact the cariostatic properties of fluoride in milk.

Longitudinal analyses of early lesions by fluorescence: an observational study.

Previous caries experience correlates to future caries risk; thus, early identification of lesions has importance for risk assessment and management. In this study, we aimed to determine if Quantitative Light-induced Fluorescence (QLF) parameters--area (A [mm(2)]), fluorescence loss (F [%]), and Q [% × mm(2)]--obtained by image analyses can predict lesion progression. We secured consent from 565 children (from 5-13 years old) and their parents/guardians and examined them at baseline and regular intervals over 48 months according to the International Caries Detection Assessment System (ICDAS), yearly radiographs, and QLF. QLF images from surfaces with ICDAS 0/1/2/3/4 at baseline that progressed (N = 2,191) to cavitation (ICDAS 5/6) or fillings and surfaces that did not progress to cavitation/fillings (N = 4,141) were analyzed independently for A, F, and Q. Linear mixed-effects models were used to compare means and slopes (changes over time) between surfaces that progressed and those that did not. QLF A, F, and Q increased at a faster rate for surfaces that progressed than for surfaces that did not progress (p = .0001), regardless of type of surface or baseline ICDAS score. AUC for ICDAS ranged from 0.65 to 0.80, but adding QLF information improved AUC (0.82-0.87, p < .0005). We concluded that faster changes in QLF variables can indicate lesion progression toward cavitation and be more clinically relevant than actual QLF values.

Interplay between experimental dental pellicles and stannous-containing toothpaste on dental erosion-abrasion.

The interaction between stannous-containing dentifrice slurry and experimentally formed pellicles was investigated on enamel and root dentin using an erosion-remineralization-abrasion cycling model. The remineralizing solutions contained no proteins (negative control), mucin, casein, mucin + casein or albumin, for experimental pellicle formation. Toothbrushing was performed with fluoride toothpaste, with (TP + Sn) and without (TP) 3,500 ppm Sn. TP + Sn reduced surface loss for both enamel and root dentin (p < 0.05). The association between TP + Sn and albumin resulted in a significantly lower enamel surface loss (p < 0.05), suggesting positive interaction of stannous ion and albumin on dental erosion-abrasion protection. A similar trend was observed for root dentin, although less pronounced.

A defined-multispecies microbial model for studying enamel caries development.

The aims of this study were to describe and validate an in vitro multispecies microbial biofilm model for caries development by evaluating the effects of varying medium concentration of sucrose (0.5 and 1.0%) and fluoride (0.4, 0.8 and 1.0 ppm F) in study 1, and calcium (1.0 and 2.0 mM Ca) in study 2. Defined-multispecies biofilms, formed by Lactobacillus casei, Streptococcus mutans, S. salivarius and S. sanguinis, were grown on the surface of salivary-pellicle-coated enamel slabs, with known baseline surface hardness; growth medium was changed daily. Counts of viable cells on biofilms and the percentage of surface microhardness change (%SMC), lesion depth (LD) and integrated mineral loss (IML) on enamel slabs were assessed after 4 days of biofilm formation under the tested conditions. Counts of viable cells on biofilms were significantly affected by sucrose, fluoride and calcium concentrations (p < 0.05). There was a decrease in %SMC in response to increased fluoride and calcium concentrations (p < 0.001). Lower IML (p < 0.001) and LD (p < 0.05) were found in the presence of 0.8 and 1.0 ppm F. A negative correlation was found between the response variables (%SMC, LD and IML) and fluoride and calcium concentrations. The results suggest that the microbial caries model developed was able to show distinct levels of caries inhibition in response to fluoride and calcium concentrations, corroborating clinical observations. An effect of sucrose concentration on caries development was found only in the presence of the lowest fluoride concentration.

Remineralization models.

During the ICNARA 2 conference, a workshop was held on remineralization models. The group considered the role of remineralization models, whether there was one ideal in situ model design, what essential features should be incorporated into an in situ model, other alternative models, and what new methods for measuring remineralization were on the horizon. This paper summarizes the discussion. In situ and other caries models can be used as a surrogate for caries clinical trials but only when data exist to validate the model. In situ model design should be flexible to allow for investigation of different aspects of the caries process; however, several essential features were identified that should be incorporated into the study design. A range of other caries models was discussed, including the study of non-cavitated lesions, lesions post-orthodontic therapy, plaque retention models to form more standardized lesions, and the study of root caries lesions. Numerous new methods for quantifying remineralization were discussed, but it was considered that these require validation before they can be used in clinical trials.

The natural history of dental caries lesions: a 4-year observational study.

Dental caries is a ubiquitous disease affecting all age groups and segments of the population. It is known that not all caries lesions progress to cavitation, but little is known regarding the progression pattern of caries lesions. This study's purpose was to evaluate the natural history of dental caries using a standardized, visually based system, the International Caries Detection and Assessment System (ICDAS). The study population consisted of 565 consenting children, who were enrolled and examined at baseline and at regular intervals over 48 months with ICDAS and yearly bitewing radiographs. Of these, 338 children completed all examinations. Not all lesions cavitated at the same rate, differing by surface type and baseline ICDAS severity score and activity status. With increasing severity, the percentage of lesions progressing to cavitation increased: 19%, 32%, 68%, and 66% for ICDAS scores 1, 2, 3, and 4, respectively. Lesions on occlusal surfaces were more likely to cavitate, followed by buccal pits, lingual grooves, proximal surfaces, and buccal and lingual surfaces. Cavitation was more likely on molars, followed by pre-molars and anterior teeth. Predictors of cavitation included age, gender, surfaces and tooth types, and ICDAS severity/activity at baseline. In conclusion, characterization of lesion severity with ICDAS can be a strong predictor of lesion progression to cavitation.

Effective use of self-care fluoride administration in Asia.

The caries-preventive benefits of fluoride are generally accepted by dental researchers and practicing professionals worldwide. The benefits of fluoride toothpastes and mouthrinses have been supported by several high-quality systematic reviews. The formulation of a fluoride toothpaste and biological (salivary flow rate) and behavioral factors (brushing frequency, brushing time, post-brushing rinsing practices, timing of brushing, and amount of toothpaste applied) can influence anticaries efficacy. Fluoride mouthrinses have simpler formulations and can have better oral fluoride retention profiles than fluoride toothpastes, depending on post-brushing rinsing behaviors. Fluoride continues to be the mainstay of caries control; however, there is still the need to determine the most effective approach for fluoride utilization in children and adults who remain caries-active.

In situ evaluation of the erosive potential of orange juice modified by food additives.

The aim of this study was to evaluate the erosive potential of orange juice modified with food-approved additives: 0.4 g/l of calcium (Ca) from calcium lactate pentahydrate, 0.2 g/l of linear sodium polyphosphate (LPP) or their combination (Ca+LPP) were added to a commercially available orange juice (negative control, C-). A commercially available calcium-modified orange juice (1.6 g/l of calcium) was the positive control (C+). These juices were tested using a short-term erosion in situ model, consisting of a five-phase, single-blind crossover clinical trial involving 10 subjects. In each phase, subjects inserted custom-made palatal appliances containing 8 bovine enamel specimens in the mouth and performed erosive challenges for a total of 0 (control), 10, 20, and 30 min. Two specimens were randomly removed from the appliances after each challenge period. Enamel surface microhardness was measured before and after the clinical phase and the percentage of surface microhardness change (%SMC) was determined. Before the procedures, in each phase, the subjects performed a taste test, where the juice assigned to that phase was blindly compared to C-. Overall, C+ showed the lowest %SMC, being the least erosive solution (p < 0.05), followed by Ca+LPP and Ca, which did not differ from each other (p > 0.05). LPP and C- were the most erosive solutions (p < 0.05). Taste differences were higher for C+ (5/10 subjects) and Ca (4/10 subjects), but detectable in all groups, including C- (2/10 subjects). Calcium reduced the erosive potential of the orange juice, while no protection was observed for LPP.

Methodology and models in erosion research: discussion and conclusions.

This paper summarises the discussions which took place at the Workshop on Methodology in Erosion Research in Zürich, 2010, and aims, where possible, to offer guidance for the development and application of both in vitro and in situ models for erosion research. The prospects for clinical trials are also discussed. All models in erosion research require a number of choices regarding experimental conditions, study design and measurement techniques, and these general aspects are discussed first. Among in vitro models, simple (single- or multiple-exposure) models can be used for screening products regarding their erosive potential, while more elaborate pH cycling models can be used to simulate erosion in vivo. However, in vitro models provide limited information on intra-oral erosion. In situ models allow the effect of an erosive challenge to be evaluated under intra-oral conditions and are currently the method of choice for short-term testing of low-erosive products or preventive therapeutic products. In the future, clinical trials will allow longer-term testing. Possible methodologies for such trials are discussed.

In situ fluoride response of caries lesions with different mineral distributions at baseline.

The present in situ study investigated the fluoride response of caries lesions with similar mineral loss but two distinct mineral distributions (low- and high-'R', calculated as the ratio of mineral loss to lesion depth). Sixteen subjects wore eight gauze-covered enamel specimens with preformed lesions placed buccally on their mandibular partial dentures for periods up to 4 weeks. The participants brushed twice daily for 1 min with an 1,100 ppm F (as NaF) dentifrice. After 3 and 4 weeks, specimens were retrieved and analyzed microradiographically (TMR) and by quantitative light fluorescence (QLF). TMR results revealed that low- and high-R lesions showed opposite behaviors - low-R lesions further demineralized, whereas high-R lesions exhibited some remineralization. In comparison, lesion depth increased in low-R, but remained unchanged in high-R lesions; R decreased in both, but more in high-R lesions; mineral density at the lesion surface remained unchanged in low-R, but increased in high-R lesions. Differences in mineral loss between lesion types increased further between 3 and 4 weeks. QLF did not mirror TMR results as low-R lesions were found to remineralize, whereas high-R lesions remained unchanged. It is likely that low-R lesions differ from high-R lesions chemically and microstructurally; therefore rendering low-R lesion more susceptible to further dissolution. During lesion formation, low-R in contrast to high-R lesions may not lose all of the solubility-determining impurities such as magnesium and carbonate, which can reprecipitate again in different mineral phases within the lesion. In conclusion, mineral distribution at baseline directly impacts in situ lesion response to fluoride.

Identification of caries risk factors in toddlers.

The purpose of this study was to identify risk factors to predict caries progression in toddlers in primary-healthcare settings for the cost-effective targeting of preventive and referral strategies. We examined 329 children (26 ± 6 mos old) twice, one year apart, in Indiana, USA. A 107-item structured interview was used to collect information from the primary caregiver and child on factors/beliefs/perceptions/behaviors that could affect caries development, transmission of bacteria, medical-dental health, and access to care. Bacterial levels, gingivitis, dental plaque, and caries experience were assessed. Multiple-variable logistic regression models of caries progression toward cavitation included family caries experience, transmission-related behaviors, dietary factors, health beliefs, and lower income, but differed in selected predictors/predictive power by race/ethnicity. Addition of clinical variables did not significantly improve the prediction.