Mapping of a Subgingival Dual-Species Biofilm Model Using Confocal Raman Microscopy.

Techniques for continuously monitoring the formation of subgingival biofilm, in relation to the determination of species and their accumulation over time in gingivitis and periodontitis, are limited. In recent years, advancements in the field of optical spectroscopic techniques have provided an alternative for analyzing three-dimensional microbiological structures, replacing the traditional destructive or biofilm staining techniques. In this work, we have demonstrated that the use of confocal Raman spectroscopy coupled with multivariate analysis provides an approach to spatially differentiate bacteria in an in vitro model simulating a subgingival dual-species biofilm. The present study establishes a workflow to evaluate and differentiate bacterial species in a dual-species in vitro biofilm model, using confocal Raman microscopy (CRM). Biofilm models of Actinomyces denticolens and Streptococcus oralis were cultured using the "Zürich in vitro model" and were analyzed using CRM. Cluster analysis was used to spatially differentiate and map the biofilm model over a specified area. To confirm the clustering of species in the cultured biofilm, confocal laser scanning microscopy (CLSM) was coupled with fluorescent in vitro hybridization (FISH). Additionally, dense bacteria interface area (DBIA) samples, as an imitation of the clusters in a biofilm, were used to test the developed multivariate differentiation model. This confirmed model was successfully used to differentiate species in a dual-species biofilm and is comparable to morphology. The results show that the developed workflow was able to identify main clusters of bacteria based on spectral "fingerprint region" information from CRM. Using this workflow, we have demonstrated that CRM can spatially analyze two-species in vitro biofilms, therefore providing an alternative technique to map oral multi-species biofilm models.

Potencial erosivo de jugos de frutas amazónicas / Erosive potential of juices of amazonian fruits

RESUMEN La erosión dental es la pérdida irreversible de la superficie del esmalte o dentina, debido a exposición frecuente de ácidos de origen no bacteriano. A pesar de que ciertos jugos de frutas presentan potencial erosivo in vitro, no existe una evidencia conclusiva al respecto. Objetivos: Evaluar in situ el potencial erosivo de jugos de frutas amazónicas sobre el esmalte dental. Material y métodos: Se evaluó in situ la microdureza superficial Vickers (MSV) del esmalte dental luego de la exposición a las bebidas Physalis Peruviana (aguaymanto), Averrhoa Carambola (carambola), Myrciaria Dubia (camu camu), Coca cola (control positivo) y agua destilada (control negativo). Participaron quince voluntarios (18 a 30 años) quienes utilizaron placas palatinas para reproducir el medio de almacenamiento. Se colocaron 6 fragmentos por placa. Las placas fueron expuestas a las diferentes bebidas 4 v/d (9:00 am, 11:00 am, 13:00 pm y 15:00 pm) durante 5 minutos por 5 días. Por cada ciclo erosivo se expuso a dos bebidas, inmediatamente los dispositivos palatinos fueron recolocados en la boca de los participantes. Hubo un periodo de washout de 8 días entre cada ciclo. Se calculó la diferencia de MSV antes y después de la exposición. El análisis de ANOVA/Tukey se utilizó para determinar las diferencias entre las bebidas en el programa SPSS 19, con un nivel de significancia de 0,5%. Resultados: Las cuatro bebidas evaluadas disminuyeron la MSV del esmalte (p<0,05) sin diferencia significativa entre ellas. Conclusiones: Los jugos a base de camu camu, aguaymanto y carambola son potencialmente erosivos.

SUMMARY Dental erosion is the irreversible loss of the surface of the enamel or dentin, due to frequent exposure of non- bacterial acids. Although certain fruit juices have erosive potential in vitro, there is no conclusive evidence in this regard. Objective: To evaluate in situ the erosive potential of Amazonian fruit juices on dental enamel. Material and methods: The Vickers surface microhardness (VMH) of dental enamel was evaluated in situ after exposure to drinks Physalis Peruviana (aguaymanto), Averrhoa Carambola (carambola), Myrciaria Dubia (camu camu), Coca cola (positive control) and distilled water (negative control). Fifteen volunteers (18 to 30 years) participated who wore palatal appliances to reproduce the storage medium. Each one containing 6 enamel blocks. The appliances were exposed to the different drinks 4 times a day (9:00 am, 11: 00 am, 13:00 pm and 15:00 pm) for 5 minutes during 5 days. For each erosive cycle, they were exposed to two drinks, immediately the palatal devices were repositioned in the participants' mouth. There was an 8-day washout period between each cycle. The difference in VMH before and after exposure was calculated. The ANOVA/Tukey analysis was used to determine the differences between beverages in the SPSS 19 program, with a significance level of 0.5%. Results: The four experimental groups decreased enamel VMH (p<0.05) without significant difference between them. Conclusions: The juices based on camu camu, aguaymanto and carambola are potentially erosive.

Confocal Raman microscopy to identify bacteria in oral subgingival biofilm models.

The study of oral disease progression, in relation to the accumulation of subgingival biofilm in gingivitis and periodontitis is limited, due to either the ability to monitor plaque in vitro. When compared, optical spectroscopic techniques offer advantages over traditional destructive or biofilm staining approaches, making it a suitable alternative for the analysis and continued development of three-dimensional structures. In this work, we have developed a confocal Raman spectroscopy analysis approach towards in vitro subgingival plaque models. The main objective of this study was to develop a method for differentiating multiple oral subgingival bacterial species in planktonic and biofilm conditions, using confocal Raman microscopy. Five common subgingival bacteria (Fusobacterium nucleatum, Streptococcus mutans, Veillonella dispar, Actinomyces naeslundii and Prevotella nigrescens) were used and differentiated using a 2-way orthogonal Partial Least Square with Discriminant Analysis (O2PLS-DA) for the collected spectral data. In addition to planktonic growth, mono-species biofilms cultured using the 'Zürich Model' were also analyzed. The developed method was successfully used to predict planktonic and mono-species biofilm species in a cross validation setup. The results show differences in the presence and absence of chemical bands within the Raman spectra. The O2PLS-DA model was able to successfully predict 100% of all tested planktonic samples and 90% of all mono-species biofilm samples. Using this approach we have shown that Confocal Raman microscopy can analyse and predict the identity of planktonic and mono-species biofilm species, thus enabling its potential as a technique to map oral multi-species biofilm models.

Clinical assessment of a manual toothbrush with CrissCross and tapered bristle technology on gingivitis and plaque reduction.

PURPOSE: The primary aim of this study was to evaluate the gingivitis-reduction efficacy of an experimental manual toothbrush with CrissCross and tapered bristle technology in comparison with a marketed control manual toothbrush with traditional design and non-tapered bristles. In addition, the study compared the two toothbrushes for plaque-reduction efficacy. METHODS: This was a randomized, controlled, parallel group, examiner-blind, single-center, 4-week clinical trial with adult subjects in good general health. All subjects had presence of gingivitis (at least 10 bleeding sites). The subjects were randomly assigned to one of two treatment groups: a manual toothbrush having CrissCross and tapered bristle technology (tapered group: Oral-B CrossAction Ultrathin manual toothbrush); or a traditional flat-trim design and regular non-tapered bristles (control group: Oral-B Indicator Soft 35 manual toothbrush). Subjects were instructed to brush twice-daily for 4 weeks with their assigned brush and a standard sodium fluoride dentifrice. At baseline, Week 2, and Week 4, gingivitis was assessed using the Mazza Modification of the Gingival Bleeding Index (Mazza GI) and pre-brushing whole-mouth plaque was measured using the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI). RESULTS: 100 subjects (50 per group) were randomized to treatment and assessed at baseline, and 97 subjects (48 in the tapered group and 49 in the control group) completed the study. At both Weeks 2 and 4, both groups showed a significant (P< 0.005) reduction versus baseline in Mazza GI and number of bleeding sites, and the tapered group showed a significantly (P< 0.001) greater reduction from baseline for both these assessments compared to the control group. By Week 4 the tapered group showed a reduction from baseline of 17.9% in Mazza GI and 38.5% in the number of bleeding sites; the corresponding figures for the control group were 7.5% and 12.6%, respectively. Both groups showed a significant (P< 0.001) reduction versus baseline in TMQHPI by Week 4, with no significant (P=0.06) between-group difference. CLINICAL SIGNIFICANCE: The twice-daily use of a manual toothbrush with CrissCross design and tapered bristles had a statistically significantly greater gingivitis reduction compared to a manual toothbrush of traditional flat-trim design and regular non-tapered bristles, which could be a clinical advantage.

A 5-week randomized clinical evaluation of a novel electric toothbrush head with regular and tapered bristles versus a manual toothbrush for reduction of gingivitis and plaque.

OBJECTIVE: To evaluate the efficacy of an oscillating-rotating (O-R) electric rechargeable toothbrush with a novel round brush head comprised of regular and tapered bristles in reducing plaque and gingivitis versus a manual toothbrush. METHODS: This was a randomized, examiner-blind, parallel group, five-week study. Participants with mild-to-moderate plaque and gingivitis received an oral examination and were evaluated for baseline plaque (Rustogi Modified Navy Index), gingivitis (Modified Gingival Index) and gingival bleeding (Gingival Bleeding Index). Qualifying participants were randomly assigned to the novel Oral-B sensitive brush head (EB60) on an Oral-B Vitality O-R handle (D12) or an ADA manual toothbrush. Participants brushed twice daily with the assigned brush and a standard fluoride dentifrice for 5 weeks before returning for an oral examination and plaque and gingivitis evaluations. RESULTS: A total of 150 participants were randomized to treatment and completed the study (mean age = 45.7 years). Both brushes demonstrated a statistically significant reduction in number of bleeding sites versus baseline (P < 0.001). At Week 5, the number of bleeding sites was reduced from baseline by 11.15 (52.2%) for the O-R brush and 5.04 (23.6%) for the manual brush. The treatment difference was statistically significant (P < 0.001). Significant reductions versus baseline (P < 0.001) were also seen for both brushes for MGI, GBI and Rustogi plaque measures (whole mouth, gingival margin and proximal), but the O-R brush produced significantly greater reductions versus the manual brush (P < 0.001). CONCLUSION: The O-R handle and round brush head with tapered and regular bristles produced greater plaque and gingivitis reductions than the manual brush.

Cómo desarrollar ciencia odontológica en el Perú / How to develop dental science in Peru

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Clinical effect of a manual toothbrush with tapered filaments on dental plaque and gingivitis reduction.

PURPOSE: To evaluate the anti-plaque efficacy (Study 1) and the anti-gingivitis efficacy (Study 2) of a manual toothbrush with tapered bristles compared to marketed control manual toothbrushes. METHODS: Studies 1 and 2 were independent, randomized and controlled, single-center, examiner-blind clinical trials in generally healthy adults. Study 1 included a 2-day acclimation period, followed by a 5-day twice daily toothbrushing test phase with the assigned brush. Baseline and Day 5 pre- and post-brushing plaque levels were assessed via Turesky Modified Quigley-Hein Plaque Index (TMQHPI). In Study 2, subjects with existing gingivitis brushed with their assigned toothbrush twice daily for 4 weeks. Gingivitis was measured using the Mazza Modification of the Papillary Bleeding Index at Baseline and Weeks 2 and 4. In both trials, subjects were randomly assigned to either the manual toothbrush with tapered bristles (Oral-B Super Thin Indicator toothbrush, OM159) or the marketed control (Study 1: Oral-B Complete Clean & Sensitive toothbrush; Study 2: Crest Pro-Health Complete 7 Brush 35 toothbrush) for use with a regular fluoridated dentifrice. RESULTS: 40 (Study 1) and 63 (Study 2) subjects were randomized in each trial. In Study 1, both the tapered bristle and marketed control brushes provided significant (P< 0.0001) mean whole mouth plaque reductions at Day 1 and Day 5 post-brushing relative to pre-brushing as measured via TMQPHI, with no between-brush significant differences. Both groups showed a significant reduction in Day 5 post-brushing mean plaque scores versus Day 1 pre- brushing mean plaque scores (P< 0.0001), but the reductions were not significantly different between groups (P= 0.4274). In Study 2, both the tapered bristle brush and the marketed control brush produced significant (P< 0.0001) reductions in both gingivitis and number of gingival bleeding sites at both Weeks 2 and 4 versus baseline. At Week 4, the tapered filament toothbrush group showed 8.6% less gingivitis (P= 0.0017) and 33.4% fewer bleeding sites (P= 0.0030) versus the control brush. All toothbrushes were well-tolerated. CLINICAL SIGNIFICANCE: Twice daily customary use of a manual toothbrush with tapered bristles provided clinically meaningful plaque and gingivitis reduction benefits.

Randomised clinical study of plaque removal efficacy of a power toothbrush in a paediatric population.

BACKGROUND: Clinical investigations of plaque removal efficacy of power toothbrushes in children are limited. AIM: To compare plaque removal of a power versus manual toothbrush in a paediatric population. DESIGN: This was a randomised, replicate-use, single-brushing, examiner-blinded, two-treatment, four-period crossover clinical trial in children 8-11 years of age. Subjects were randomly assigned to a treatment sequence involving an oscillating-rotating power toothbrush and a manual toothbrush control. Subjects brushed under supervision with a NaF dentifrice. Plaque was assessed pre- (baseline) and post-brushing using the Turesky Modification of the Quigley-Hein Plaque Index by two examiners. Plaque scores were averaged for mixed and permanent dentition on a per-subject basis and analysed using a mixed-model ancova for a crossover design. RESULTS: Forty-one subjects (mean 9.0 years) were randomised and completed the trial. Both the power brush and manual brush provided statistically significant mean plaque reductions versus baseline in all analyses (P < 0.001). For both examiners, plaque removal was significantly (P < 0.001) larger for the power brush in permanent and mixed dentitions. The interexaminer correlations for the permanent dentition were strong (ICC = 0.68-0.88) for pre-brushing plaque across all periods. CONCLUSIONS: An oscillating-rotating power toothbrush provided superior plaque reduction versus a manual toothbrush in children.

In situ effect of a CPP-ACP chewing gum on enamel erosion associated or not with abrasion.

OBJECTIVES: The purpose of this study is to analyze the in situ effect of a casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) chewing gum on human enamel erosion lesion associated or not with abrasion. MATERIAL AND METHODS: A three-way crossover study of 7 days was conducted involving 10 volunteers subjected to the same protocol: (G1) CPP-ACP sugar-free chewing gum, (G2) regular sugar-free chewing gum without CPP-ACP, and (G3) saliva-no chewing gum. An abrasion test was included in each phase. A 3D non-contact profilometry measurement of lesion depth and surface roughness was obtained of sound and eroded surfaces. A salivary calcium concentration was determined for all volunteers. ANOVA followed by Tukey's test were used with a p < 0.05. RESULTS: The enamel depth and the enamel surface roughness of the CPP-ACP gum group were significantly lower than the others (ANOVA, p < 0.05). No significant differences were observed between the treatments when associated with abrasion (p > 0.05). A positive and significant correlation was seen between the lesion depth and enamel surface roughness for GI (r = 0.87, p = 0.00) and GIII (r = 0.79, p = 0.00) groups. The estimated total calcium presented in the saliva after the chewed CPP-ACP gum showed no statistical significance between the mean absorbance values at the different time collections (p > 0.05). CONCLUSIONS: It is demonstrated that the incorporation of the CPP-ACP into a sugar-free gum significantly increased the remineralization/protection of eroded enamel surface. CLINICAL RELEVANCE: The CPP-ACP added to gum may be a suitable alternative vehicle, to deliver calcium ions to saliva and therefore protecting enamel.

Influence of the Culture Medium in Dose-Response Effect of the Chlorhexidine on Streptococcus mutans Biofilms.

The aim of this study was to evaluate the influence of culture medium on dose-response effect of chlorhexidine (CHX) on Streptococcus mutans UA159 biofilm and validate the use of the cation-adjusted-Müller-Hinton broth (MH) for the evaluation of antibacterial activity. Ultrafiltered Tryptone-Yeast Extract Broth (UTYEB) was compared against MH and MH with blood supplementation (MHS). For each medium, six groups (n = 4) were assessed: two negative control groups (baseline 48 and 120 h) and four experimental groups (0.0001, 0.001, 0.012, and 0.12% CHX). S. mutans biofilm grew on glass slides of each media containing 1% sucrose. After 48 h of growth, biofilms of baseline 48 h were collected and the other groups were treated for 1 min, twice a day, for 3 days, with their respective treatments. The media were changed daily and pH was measured. After 120 h, biofilms were collected and dry weight and viable microorganisms were determined. Results showed CHX dose-response effect being observed in all media for all the variables. However, MH and MHS showed higher sensitivity than UTYEB (p < 0.05). We can conclude that the culture medium does influence dose-response effect of CHX on Streptococcus mutans biofilm and that MH can be used for antibacterial activity.

A randomized 12-week clinical comparison of an oscillating-rotating toothbrush to a new sonic brush in the reduction of gingivitis and plaque.

OBJECTIVE: To evaluate the efficacy of a marketed oscillating-rotating (O-R) power toothbrush (Oral-B Triumph with SmartGuide and FlossAction brush head, D34/EB25) to a new sonic toothbrush (Sonicare FlexCare Platinum) in the reduction of gingivitis and plaque over a 12-week test period. METHODS: This was a single center, randomized, open label, examiner-blind, two-treatment, parallel group study. Subjects who met the entrance criteria were enrolled in the study and randomly assigned to either the O-R or sonic treatment group. Subjects brushed with their assigned toothbrush and a marketed fluoride dentifrice for two minutes twice daily at home for 12 weeks. Gingivitis and plaque were evaluated at Baseline, Week 6, and Week 12. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI), and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data were analyzed using an Analysis of Covariance (ANCOVA) with Baseline as the covariate. RESULTS: In total, 130 subjects (65 per group) were randomized to treatment and 127 subjects completed the study. Both brushes produced statistically significant (p < 0.001) reductions in gingivitis and plaque measures relative to Baseline. At Week 12, the O-R brush demonstrated significantly greater reductions than the sonic brush in whole mouth gingivitis measures (p = 0.007). Additionally, the O-R brush presented significantly fewer bleeding sites (p < 0.007) and significantly greater reductions in whole mouth plaque measures (p < or = 0.035) at Weeks 6 and 12 versus the sonic brush. The benefit for the O-R brush versus the sonic brush at Week 12 was 11.7% for gingivitis, 19.8% for number of bleeding sites, and 12.2% for whole mouth plaque. There were no adverse events reported or observed for either brush. CONCLUSION: The oscillating-rotating toothbrush demonstrated statistically significantly greater reductions in whole mouth plaque at Weeks 6 and 12, as well as significantly greater gingivitis reductions over the long-term (12 weeks), compared to the new sonic toothbrush.

A 4-week clinical comparison of an oscillating-rotating power brush versus a marketed sonic brush in reducing dental plaque.

PURPOSE: To assess the plaque removal efficacy of an oscillating-rotating power brush relative to a newly-introduced sonic power brush. METHODS: This study used a randomized, examiner-blind, single-center, two-treatment, parallel group 4-week design. Subjects with pre-existing plaque scores of at least 1.75 on the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI) were evaluated for baseline whole mouth and approximal plaque scores. They received either the oscillating-rotating brush (Oral-B Professional Care 1000, sold as Oral-B Professional Care 600 in some regions, with the Oral-B Precision Clean brush head, D16u/EB20) or the sonic brush (Colgate ProClinical C200 with Colgate Triple Clean brush head) and brushed twice-daily with the assigned brush and a standard fluoride dentifrice for 4 weeks before returning for plaque measurements. Prior to baseline and the Week 4 measurements, participants abstained from oral hygiene for 12 hours and from eating, chewing gum and drinking for 4 hours. RESULTS: A total of 131 subjects were enrolled in the study at baseline, with all completing the study: 65 in the oscillating-rotating group, and 66 in the sonic group. Both brushes significantly reduced plaque over the 4-week study period. The oscillating-rotating brush was statistically significantly more effective in reducing plaque (P < 0.001) than the sonic brush. Compared to the sonic power brush, the adjusted mean plaque reduction scores for the oscillating-rotating power brush were more than five times greater for whole mouth and approximal areas.

A randomized clinical trial evaluating gingivitis and plaque reduction of an oscillating-rotating power brush with a new brush head with angled bristles versus a marketed sonic brush with self-adjusting technology.

PURPOSE: To compare the efficacy of an oscillating-rotating power toothbrush with a novel brush head incorporating angled CrissCross bristles (Oral-B Pro 7000 SmartSeries and Oral-B CrossAction brush head) versus a marketed sonic toothbrush (Colgate ProClinical A1500 with the Triple Clean brush head) in the reduction of gingivitis and plaque over a 6-week period. METHODS: This was a single center, randomized, open label, examiner-blind, 2-treatment, parallel group study. Study participants who met the entrance criteria were enrolled in the study and randomly assigned to one of the two toothbrush groups. Study participants brushed with their assigned toothbrush and a marketed fluoride dentifrice for 2 minutes twice daily at home for 6 weeks. Gingivitis and plaque were evaluated at baseline and Week 6. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI) and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data was analyzed using the ANCOVA with baseline as the covariate. RESULTS: In total, 130 study participants were randomized to treatment resulting in 64 study participants per group completing the study. Both brushes produced statistically significant (P < 0.001) reductions in gingivitis and plaque measures relative to baseline. The oscillating-rotating,brush with the novel brush head demonstrated statistically significantly (P < 0.05) greater reductions in all gingivitis measures, as well as whole mouth and interproximal plaque measures, compared to the sonic toothbrush. The benefit for the oscillating- rotating brush over the sonic brush was 21.3% for gingivitis, 35.7% for gingival bleeding, 34.7% for number of bleeding sites, 17.4% for whole mouth plaque, and 21.2% for interproximal plaque. There were no adverse events reported or observed for either brush.

The effect of iron on Streptococcus mutans biofilm and on enamel demineralization

Iron (Fe) may have an anticaries effect by specific inhibition of glycosyltransferase (GTF) enzymes of Streptococcus mutans, but this hypothesis has not yet been clarified. In this study, S. mutans biofilms were formed on blocks of bovine dental enamel of a predetermined surface hardness (SH). These biofilms were exposed eight times/day to 10% sucrose, and two times/day they were subjected to one of the following treatments: G1, 0.9% NaCl as a negative control; G2, 0.12% chlorhexidine digluconate (CHX) as a positive antibacterial control; G3, 0.05% NaF (225 ppm F) as a positive anticaries control; G4, G5, and G6, ferrous sulfate (Fe2+) at concentrations of 1.0, 10.0, and 100.0 µg Fe/mL, respectively. The experiment was performed in triplicate and was repeated three times (n = 9). The pH of the culture medium was determined every 24 h as an indicator of the biofilm's acidogenicity. The biofilm formed on each block was collected for determination of the viable bacteria and concentration of extracellular polysaccharides (EPS). Enamel SH was again determined and the percentage of SH loss (%SHL) was calculated as an indicator of demineralization. Iron treatment reduced the number of viable bacteria formed in the S. mutans biofilm (p = 0.04), in a dose-dependent manner, and also reduced the enamel's %SHL (p = 0.005). At 100 µg/mL, Fe reduced enamel demineralization as effectively as CHX and NaF (p < 0.05), but it did not inhibit EPS production. In conclusion, the data suggest that the anticaries mechanism of action of Fe may not involve the oxidative inhibition of GTFs.

The effect of iron on Streptococcus mutans biofilm and on enamel demineralization.

Iron (Fe) may have an anticaries effect by specific inhibition of glycosyltransferase (GTF) enzymes of Streptococcus mutans, but this hypothesis has not yet been clarified. In this study, S. mutans biofilms were formed on blocks of bovine dental enamel of a predetermined surface hardness (SH). These biofilms were exposed eight times/day to 10% sucrose, and two times/day they were subjected to one of the following treatments: G1, 0.9% NaCl as a negative control; G2, 0.12% chlorhexidine digluconate (CHX) as a positive antibacterial control; G3, 0.05% NaF (225 ppm F) as a positive anticaries control; G4, G5, and G6, ferrous sulfate (Fe2+) at concentrations of 1.0, 10.0, and 100.0 µg Fe/mL, respectively. The experiment was performed in triplicate and was repeated three times (n = 9). The pH of the culture medium was determined every 24 h as an indicator of the biofilm's acidogenicity. The biofilm formed on each block was collected for determination of the viable bacteria and concentration of extracellular polysaccharides (EPS). Enamel SH was again determined and the percentage of SH loss (%SHL) was calculated as an indicator of demineralization. Iron treatment reduced the number of viable bacteria formed in the S. mutans biofilm (p = 0.04), in a dose-dependent manner, and also reduced the enamel's %SHL (p = 0.005). At 100 µg/mL, Fe reduced enamel demineralization as effectively as CHX and NaF (p < 0.05), but it did not inhibit EPS production. In conclusion, the data suggest that the anticaries mechanism of action of Fe may not involve the oxidative inhibition of GTFs.

Photoelastic evaluation of the effect of composite formulation on polymerization shrinkage stress

We compared polymerization stress in two commercial composites and three experimental composites made using camphorquinone (CQ) and/or phenylpropanedione (PPD) as photoinitiators. The internal surfaces of photoelastic resin discs with cylindrical cavities were roughened and treated with adhesive. Composites were divided into five groups: two commercial composites (Filtek Silorane and Filtek Z250) and three experimental composites with CQ/amine, CQ/PPD/amine, and PPD/amine. Composites were photopolymerized inside cavities, and subjected to photoelastic analysis immediately and at 24 hours and 7 days later using a plane polariscope. Stress created by Silorane (3.08 ± 0.09 MPa) was similar to that of Z250 (3.19 ± 0.13 MPa) immediately after photopolymerization (p > 0.05). After 24 hours and 7 days, Z250 (3.53 ± 0.15 and 3.69 ± 0.10 MPa, respectively) showed higher stress than Silorane (3.19 ± 0.10 and 3.16 ± 0.10 MPa, respectively). Qualitative analysis immediately after photopolymerization showed composite/CQ promoted higher stress than PPD, but stress levels at other evaluated times were statistically similar, varying between 3.45 ± 0.11 MPa and 3.92 ± 0.13 MPa. At 24 hours and 7 days, Silorane created the lowest stress. All photoinitiators created comparable tensions during polymerization.

Photoelastic evaluation of the effect of composite formulation on polymerization shrinkage stress.

We compared polymerization stress in two commercial composites and three experimental composites made using camphorquinone (CQ) and/or phenylpropanedione (PPD) as photoinitiators. The internal surfaces of photoelastic resin discs with cylindrical cavities were roughened and treated with adhesive. Composites were divided into five groups: two commercial composites (Filtek Silorane and Filtek Z250) and three experimental composites with CQ/amine, CQ/PPD/amine, and PPD/amine. Composites were photopolymerized inside cavities, and subjected to photoelastic analysis immediately and at 24 hours and 7 days later using a plane polariscope. Stress created by Silorane (3.08 ± 0.09 MPa) was similar to that of Z250 (3.19 ± 0.13 MPa) immediately after photopolymerization (p > 0.05). After 24 hours and 7 days, Z250 (3.53 ± 0.15 and 3.69 ± 0.10 MPa, respectively) showed higher stress than Silorane (3.19 ± 0.10 and 3.16 ± 0.10 MPa, respectively). Qualitative analysis immediately after photopolymerization showed composite/CQ promoted higher stress than PPD, but stress levels at other evaluated times were statistically similar, varying between 3.45 ± 0.11 MPa and 3.92 ± 0.13 MPa. At 24 hours and 7 days, Silorane created the lowest stress. All photoinitiators created comparable tensions during polymerization.

S. mutans biofilm model to evaluate antimicrobial substances and enamel demineralization.

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37 degrees C, 10% CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12% (concentration with recognized anti-plaque effect) and 0.05% NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05% NaF did not show antimicrobial effect but had similar effect to that of 0.12% CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.

S. mutans biofilm model to evaluate antimicrobial substances and enamel demineralization

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37°C, 10 percent CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12 percent (concentration with recognized anti-plaque effect) and 0.05 percent NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05 percent NaF did not show antimicrobial effect but had similar effect to that of 0.12 percent CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.

Polarization of dental caries among individuals aged 15 to 18 years

OBJECTIVE: To evaluate the role of socioeconomic variables and self-perceived oral health in the polarization of caries among adolescents in Santa Bárbara D'Oeste, Brazil. MATERIAL AND METHODS: Cross-sectional study. Sampling was randomized and sample size was defined according to WHO criteria. Two hundred and seventy seven adolescents (15 to 18 year-old) were examined by five trained examiners that assessed DMFT index according to WHO criteria. Self-perceived oral health, access to dental services and socio-demographic variables were self-reported. Student's t tests, chi-square tests, and multivariate logistic regression (with significant caries index (SiC) as the outcome), were performed. RESULTS: Mean DMFT was 5.48 (±4.22) and the proportion of "caries free" subjects was 15.5 percent. Mean DMFT (9.71±2.85) and mean D (1.67±2.18) of SiC positive subjects were significantly higher than mean DMFT (2.88±2.17) and mean D (0.45±0.87) of SiC negative subjects (p<0.0001). Mean D of white (0.76±1.51) was significantly smaller than mean D of non-white subjects (1.32±2.01). The only variable independently associated with the "SiC positive" outcome was "report of toothache within six months prior to the study" [OR=1.83 (95 percentCI 1.08 to 3.12)], p<0.001. CONCLUSION: SiC was associated with "report of toothache" but not with socio-demographic variables in the studied population.