Long-term remineralizing effect of MI Paste Plus on regression of early caries after orthodontic fixed appliance treatment: a 12-month follow-up randomized controlled trial.

Background: Casein-phosphopeptide-amorphous-calcium-fluoride-phosphate (CPP-ACFP) can remineralize subsurface lesions. It is the active ingredient of MI-Paste-Plus® (MPP). The long-term remineralization efficacy is unknown. Objective: To evaluate the long-term effect of MPP versus a placebo paste on remineralization of enamel after fixed orthodontic treatment over a 12-month period. Design: This trial was designed as a prospective, double-blinded, placebo-controlled RCT. Methods: Patients with subsurface lesions scheduled for removal of the appliance were included. They applied either MPP or control paste once a day at bedtime for 12 months, complementary to normal oral hygiene. Main outcome measures: Changes in enamel lesions (primary outcome) were fluorescence loss and lesion area determined by quantitative light-induced fluorescence (QLF). Secondary outcomes were Microbial composition, by conventional plating, and acidogenicity of plaque, by capillary ion analysis (CIA), and lesion changes scored visually on clinical photographs. Randomization: Participants [age = 15.5 years (SD = 1.6)] were randomly assigned to either the MPP or the control group, as determined by a computer-randomization scheme, created and locked before the start of the study. Participants received neutral-coloured concealed toothpaste tubes marked A or B. Blinding: The patients and the observers were blinded with respect to the content of tube A or B. Results: A total of 51 patients were analysed; MPP (n = 25) versus control group (n = 26); data loss (n = 14). There was no significant difference between the groups over time for all the used outcome measures. There was a significant improvement in enamel lesions (fluorescence loss) over time in both groups (P < 0.001 and P < 0.001), with no differences between groups. Limitations: Being an in vivo study, non-compliance of the subjects could have influenced the result. Conclusion: The additional use of MPP in patients with subsurface enamel lesions after orthodontic fixed appliance treatment did not improve these lesions during the 1 year following debonding. Registration: This trial is registered at the medical ethical committee of the VU Medical Centre in Amsterdam (NL.199226.029.07).

The reproducibility of assessment of white spot lesions adjacent to orthodontic brackets, with a quantitative light induced fluorescence digital camera at different rotations of teeth - an in vitro study.

BACKGROUND: A quantitative light-induced fluorescence digital (QLF-D) camera is able to assess demineralizations adjacent to orthodontic brackets. Rotations of teeth during and the presence of the orthodontic appliances may influence the longitudinal follow-up of such lesions over time. METHODS: Brackets were bonded on extracted teeth: 54 incisors and 31 canines. Demineralizations were formed in vitro directly cervical of the bracket. Images were captured using a QLF-D camera mounted on an optical bench, equipped with a goniometer on a turntable. The teeth were placed in the goniometer simulating buccolingual rotation (0°, 10°, 20°), the turn-table was used for mesiodistal rotations (0°, 10°, 20°). Standardized QLF-D images were made before (with and without a wire) and after debonding at combinations of aforementioned angles of rotation. The image after debonding at 0° buccolingual and 0° mesiodistal rotation served as a control. RESULTS: The presence of a bracket resulted in a significantly higher fluorescence loss, yet a smaller lesion area (p < 0.05) in comparison to the control. A significant higher fluorescence loss was seen for rotations towards lingual relative to the 0° buccolingual and 0° mesiodistal rotation, while the effect was less explicit towards buccal. CONCLUSIONS: Fluorescence loss and lesion size are influenced by the angle of rotation under which the demineralization is photographed. The full extent of demineralizations is only apparent after debonding when photographed at rotations of 0° mesiodistal and up to 20° buccal. Precaution must be taken into account assessing demineralizations of patients undergoing treatment with fixed appliances when using a QLF-D camera.

Comparison of red autofluorescing plaque and disclosed plaque-a cross-sectional study.

OBJECTIVES: The aim of this cross-sectional study was to assess the correlation between dental plaque scores determined by the measurement of red autofluorescence or by visualization with a two-tone solution. Clinical photographs were used for this study. MATERIALS AND METHODS: Overnight plaque from the anterior teeth of 48 participants was assessed for red fluorescence on photographs (taken with a QLF-camera) using a modified Quigley & Hein (mQH) index. A two-tone disclosing solution was applied. Total disclosed plaque was clinically assessed using the mQH index. In addition, total and blue disclosed plaque was scored on clinical photographs using the mQH index. RESULTS: A strong correlation was observed between the total disclosed plaque scored on photographs and the clinical scores (r = 0.70 at site level; r = 0.88 at subject level). The correlation between red fluorescent plaque and total plaque, as assessed on the photographs, was moderate to strong and significant (r = 0.50 at the site level; r = 0.70 at the subject level), with the total plaque scores consistently higher than the red fluorescent plaque scores. The correlation between red fluorescent plaque and blue disclosed plaque was weak to moderate and significant (r = 0.30 at the site level; r = 0.50 at the subject level). CONCLUSIONS: Plaque, as scored on white-light photographs, corresponds well with clinically assessed plaque. A weak to moderate correlation between red fluorescing plaque and total disclosed plaque or blue disclosed plaque was found. CLINICAL RELEVANCE: What at present is considered to be matured dental plaque, which appears blue following the application of a two-tone disclosing solution, is not in agreement with red fluorescent dental plaque assessment.

Stability and resilience of oral microcosms toward acidification and Candida outgrowth by arginine supplementation.

Dysbiosis induced by low pH in the oral ecosystem can lead to caries, a prevalent bacterial disease in humans. The amino acid arginine is one of the pH-elevating agents in the oral cavity. To obtain insights into the effect of arginine on oral microbial ecology, a multi-plaque "artificial mouth" (MAM) biofilm model was inoculated with saliva from a healthy volunteer and microcosms were grown for 4 weeks with 1.6 % (w/v) arginine supplement (Arginine) or without (Control), samples were taken at several time-points. A cariogenic environment was mimicked by sucrose pulsing. The bacterial composition was determined by 16S rRNA gene amplicon sequencing, the presence and amount of Candida and arginine deiminase system genes arcA and sagP by qPCR. Additionally, ammonium and short-chain fatty acid concentrations were determined. The Arginine microcosms were dominated by Streptococcus, Veillonella, and Neisseria and remained stable in time, while the composition of the Control microcosms diverged significantly in time, partially due to the presence of Megasphaera. The percentage of Candida increased 100-fold in the Control microcosms compared to the Arginine microcosms. The pH-raising effect of arginine was confirmed by the pH and ammonium results. The abundances of sagP and arcA were highest in the Arginine microcosms, while the concentration of butyrate was higher in the Control microcosms. We demonstrate that supplementation with arginine serves a health-promoting function; it enhances microcosm resilience toward acidification and suppresses outgrowth of the opportunistic pathogen Candida. Arginine facilitates stability of oral microbial communities and prevents them from becoming cariogenic.

A prospective, randomized placebo-controlled clinical trial on the effects of a fluoride rinse on white spot lesion development and bleeding in orthodontic patients.

Demineralizations around orthodontic brackets are a main disadvantage of orthodontic treatment. Several methods have been advocated to prevent their development, such as fluoride rinses or varnishes. In this randomized clinical trial, a fluoride rinse (a combination of sodium fluoride and amine fluoride) was compared with a placebo rinse, to be used every evening after toothbrushing. A total of 81 participants (mean age: 13.3 yr) completed the study (mean treatment period: 24.5 months). Demineralizations, measured using quantitative light-induced fluorescence and the decayed, missing, and filled surfaces (DMFS) index, were assessed before treatment (baseline) and around 6 wk after debonding (post treatment). Bleeding scores were measured at baseline, and during and post treatment. The incidence rate ratio for demineralizations was 2.6 (95% CI: 1.1-6.3) in the placebo group vs. the fluoride group. In the fluoride group, 31% of participants developed at least one demineralization, compared with 47% in the placebo group. Relative to baseline, gingival bleeding increased significantly in the placebo group 1 yr after the start of treatment and onwards. For the fluoride group, bleeding scores during treatment were not different from those at baseline. In conclusion, using a fluoride rinse helps to maintain better oral health during fixed appliance treatment, resulting in fewer demineralizations.

Models and role models.

Developing experimental models to understand dental caries has been the theme in our research group. Our first, the pH-cycling model, was developed to investigate the chemical reactions in enamel or dentine, which lead to dental caries. It aimed to leverage our understanding of the fluoride mode of action and was also utilized for the formulation of oral care products. In addition, we made use of intra-oral (in situ) models to study other features of the oral environment that drive the de/remineralization balance in individual patients. This model addressed basic questions, such as how enamel and dentine are affected by challenges in the oral cavity, as well as practical issues related to fluoride toothpaste efficacy. The observation that perhaps fluoride is not sufficiently potent to reduce dental caries in the present-day society triggered us to expand our knowledge in the bacterial aetiology of dental caries. For this we developed the Amsterdam Active Attachment biofilm model. Different from studies on planktonic ('single') bacteria, this biofilm model captures bacteria in a habitat similar to dental plaque. With data from the combination of these models, it should be possible to study separate processes which together may lead to dental caries. Also products and novel agents could be evaluated that interfere with either of the processes. Having these separate models in place, a suggestion is made to design computer models to encompass the available information. Models but also role models are of the utmost importance in bringing and guiding research and researchers.

Towards understanding oral health.

During the last century, dental research has focused on unraveling the mechanisms behind various oral pathologies, while oral health was typically described as the mere absence of oral diseases. The term 'oral microbial homeostasis' is used to describe the capacity of the oral ecosystem to maintain microbial community stability in health. However, the oral ecosystem itself is not stable: throughout life an individual undergoes multiple physiological changes while progressing through infancy, childhood, adolescence, adulthood and old age. Recent discussions on the definition of general health have led to the proposal that health is the ability of the individual to adapt to physiological changes, a condition known as allostasis. In this paper the allostasis principle is applied to the oral ecosystem. The multidimensionality of the host factors contributing to allostasis in the oral cavity is illustrated with an example on changes occurring in puberty. The complex phenomenon of oral health and the processes that prevent the ecosystem from collapsing during allostatic changes in the entire body are far from being understood. As yet individual components (e.g. hard tissues, microbiome, saliva, host response) have been investigated, while only by consolidating these and assessing their multidimensional interactions should we be able to obtain a comprehensive understanding of the ecosystem, which in turn could serve to develop rational schemes to maintain health. Adapting such a 'system approach' comes with major practical challenges for the entire research field and will require vast resources and large-scale multidisciplinary collaborations.

White spot lesions after orthodontic treatment assessed by clinical photographs and by quantitative light-induced fluorescence imaging; a retrospective study.

OBJECTIVE: White spot lesions (WSL) are an important side-effect of orthodontic multi-bracket (MB) treatment. Standardized monitoring of such WSL may help in caries management. MATERIALS AND METHODS: In this retrospective study the discriminatory power of caries assessment on routine digital oral photographs was compared to quantitative light-induced fluorescence (QLF) imaging in monitoring WSL development after debonding of orthodontic appliances. Oral and QLF photographs captured directly after debond (T1) and 1 year thereafter (T2) of 51 subjects, treated with full MB orthodontic appliances were used. Oral photographs were assessed by use of The International Caries Detection and Assessment System (ICDAS) at both time points independently and by side-by-side comparison to assess visual transition (VT). QLF photographs were categorized based on integrated fluorescence loss at T1 and T2. RESULTS: At T1 433 and 384 lesions on 918 buccal surfaces were detected using ICDAS and QLF, respectively. For both methods these numbers were reduced at T2. Changes within ICDAS scores were recorded by VT and showed mainly lesion improvement within ICDAS score 2. CONCLUSION: The oral and QLF photographs both showed regression of WSL after debonding of MB orthodontic appliances. The VT evaluation was found to have higher discriminatory power in comparison to ICDAS.

Effect of metalloporphyrins on red autofluorescence from oral bacteria.

The aim of this study was to assess the red autofluorescence from bacterial species related to dental caries and periodontitis in the presence of different nutrients in the growth medium. Bacteria were grown anaerobically on tryptic soy agar (TSA) supplemented with nutrients, including magnesium-porphyrins from spinach and iron-porphyrins from heme. The autofluorescence was then assessed at 405 nm excitation. On the TSA without additives, no autofluorescence was observed from any of the species tested. On the TSA containing sheep blood, red autofluorescence was observed only from Parvimonas micra. When the TSA was supplemented with blood, hemin, and vitamin K, red autofluorescence was observed from Actinomyces naeslundii, Bifidobacterium dentium, and Streptococcus mutans. Finally, on the TSA supplemented with spinach extract, red autofluorescence was observed from Aggregatibacter actinomycetemcomitans, A. naeslundii, Enterococcus faecalis, Fusobacterium nucleatum, Lactobacillus salivarius, S. mutans, and Veillonella parvula. We conclude that the bacteria related to dental caries and periodontal disease exhibit red autofluorescence. The autofluorescence characteristics of the tested strains depended on the nutrients present, such as metalloporphyrins, suggesting that the metabolic products of the oral biofilm could be responsible for red autofluorescence.

Measuring dental fear using the CFSS-DS. Do children and parents agree?

BACKGROUND: In most studies, the parental version of the CFSS-DS is used; however, no information is available concerning the extent to which parents are able to report dental fear on behalf of their children. AIM: This study aims to assess whether parents are accurate reporters of their child's dental fear. METHODS: The CFSS-DS was filled out by 326 children in a classroom setting and by 167 parents (mostly mothers) at home on behalf of their child. Intraclass correlation coefficients were used as a measure of agreement between both CFSS-DS versions, and reasons for nonagreement were assessed. RESULTS: Mean CFSS-DS for children was 21.15 (SD = 6.4) and for parents 23.26 (SD = 6.7). The intraclass correlation coefficient was 0.57. After selection of the 73.1% most accurate reporting parents, the ICC was 0.90. In general, parents estimate the dental fear of their children higher than their children do (P ≤ 0.001), whereas parents of high anxious children (HAC) estimate this fear lower, and parents of low anxious children (LAC) estimate this fear higher. Anxious parents (AP) estimate the dental fear of their children significantly higher than nonanxious parents (NAP) (P ≤ 0.001), but the children of AP do not estimate their own dental fear higher than children of NAP. CONCLUSIONS: In general, parents tend to estimate the dental fear of their children slightly higher than their children.

The caries-reducing benefit of fluoride-release from dental restorative materials continues after fluoride-release has ended.

OBJECTIVE: This study tested the hypothesis that the benefit of fluoride-releasing restorative materials continues even after their reserve of fluoride has been depleted. MATERIALS AND METHODS: Pits in perspex blocks simulating cavities were filled with either a fluoride-releasing or a non-fluoride-releasing restorative material and a dentin single-section was placed 1 mm from the edge of the filled pit. These combinations were exposed to an acid gel system. Each demineralized dentin section was separated from the adjacent material and immersed in fresh demineralizing solutions. Transversal microradiographs were taken following the two experimental periods. This study defined ΔΔZ as the increase of integrated mineral loss (ΔZ) during the second acid attack. RESULTS: The first acid attack substantially demineralized the near-surface region (depth < 40 µm) in all samples. The second acid attack, however, did not cause further demineralization in this near-surface region. Instead, it demineralized dentin deeper than 40-60 µm. The ΔΔZ of the material that did not release fluoride was significantly greater than that of fluoride-releasing materials. Negative correlations were found between ΔΔZ and the mineral volume% of the near-surface region and lesion body of the initial lesions. These results indicate that the dentin mineral in the near-surface region is chemically altered to become acid-resistant fluorapatite. In addition, lesion progression during the second period of demineralization, which was fluoride-free, may have been affected for the materials that have high mineral content of the surface layer and lesion body. CONCLUSIONS: It is concluded that dentin surrounding fluoride-releasing materials is protected against demineralization even after the fluoride release has diminished.

The influence of dental caries on body growth in prepubertal children.

Dental decay and dental treatment are suggested to be related to body growth in children. The aim of this study was first to assess the relation between dental caries and body proportions cross-sectionally in a Suriname caries child population and secondly to investigate whether dental treatment had a significant influence on body growth of these children in a randomised controlled trial using different treatment strategies. Three hundred eighty 6-year-old children with untreated dental decay participated in the study. Caries prevalence and presence of dentogenic infections were recorded. All children were randomly assigned to four different treatment groups ranging from full dental treatment to no invasive treatment at all. Body growth was evaluated by children's height, weight and body mass index. Participants were evaluated after 6 months and 1, 2 and 3 years. Cross-sectionally, negative correlations were observed between anthropometric measures and the number of untreated carious surfaces and caries experience of the children. Next, no significant differences in growth pattern between the treatment groups were observed. Based on these results, it is suggested that caries activity is a negative predictor for body growth in children and dental intervention does not show significant improvement within 3 years.

Streptococcus mutans SMU.623c codes for a functional, metal-dependent polysaccharide deacetylase that modulates interactions with salivary agglutinin.

The genome sequence of the oral pathogen Streptococcus mutans predicts the presence of two putative polysaccharide deacetylases. The first, designated PgdA in this paper, shows homology to the catalytic domains of peptidoglycan deacetylases from Streptococcus pneumoniae and Listeria monocytogenes, which are both thought to be involved in the bacterial defense mechanism against human mucosal lysozyme and are part of the CAZY family 4 carbohydrate esterases. S. mutans cells in which the pgdA gene was deleted displayed a different colony texture and a slightly increased cell surface hydrophobicity and yet did not become hypersensitive to lysozyme as shown previously for S. pneumoniae. To understand this apparent lack of activity, the high-resolution X-ray structure of S. mutans PgdA was determined; it showed the typical carbohydrate esterase 4 fold, with metal bound in a His-His-Asp triad. Analysis of the protein surface showed that an extended groove lined with aromatic residues is orientated toward the active-site residues. The protein exhibited metal-dependent de-N-acetylase activity toward a hexamer of N-acetylglucosamine. No activity was observed toward shorter chitooligosaccharides or a synthetic peptidoglycan tetrasaccharide. In agreement with the lysozyme data this would suggest that S. mutans PgdA does not act on peptidoglycan but on an as-yet-unidentified polysaccharide within the bacterial cell surface. Strikingly, the pgdA-knockout strain showed a significant increase in aggregation/agglutination by salivary agglutinin, in agreement with this gene acting as a deacetylase of a cell surface glycan.

Effect of denture base-resin with prereacted glass-ionomer filler on dentin demineralization.

The demineralization of dentin was studied when placed adjacent to one of four experimental denture base-resins. These experimental resins contained polymethylmethacrylate (PMMA) and 0, 5, 10, 20 or 30 wt% surface reaction-type prereacted glass-ionomer (S-PRG) filler, respectively. A dentin thin-section was sandwiched between these resins and subjected to demineralization for 1 wk. Microradiographic analyses showed that the mineral vol% of the surface was increased, and lesion formation was inhibited, in a dose-response relationship with the amount of S-PRG filler. Moreover, the mineral loss decreased, by up to 60%, with an increasing amount of filler. These results indicate that denture base-resins containing S-PRG filler possess a substantial inhibition capability against demineralization, and this may thereby assist in preventing root caries of abutment teeth.

MLPA diagnostics of complex microbial communities: relative quantification of bacterial species in oral biofilms.

A multitude of molecular methods are currently used for identification and characterization of oral biofilms or for community profiling. However, multiplex PCR techniques that are able to routinely identify several species in a single assay are not available. Multiplex Ligation-dependent Probe Amplification (MLPA) identifies up to 45 unique fragments in a single tube PCR. Here we report a novel use of MLPA in the relative quantification of targeted microorganisms in a community of oral microbiota. We designed 9 species specific probes for: Actinomyces gerencseriae, Actinomyces naeslundii, Actinomyces odontolyticus, Candida albicans, Lactobacillus acidophilus, Rothia dentocariosa, Streptococcus mutans, Streptococcus sanguinis and Veillonella parvula; and genus specific probes for selected oral Streptococci and Lactobacilli based on their 16S rDNA sequences. MLPA analysis of DNA pooled from the strains showed the expected specific MLPA products. Relative quantification of a serial dilution of equimolar DNA showed that as little as 10 pg templates can be detected with clearly discernible signals. Moreover, a 2 to 7% divergence in relative signal ratio of amplified probes observed from normalized peak area values suggests MLPA can be a cheaper alternative to using qPCR for quantification. We observed 2 to 6 fold fluctuations in signal intensities of MLPA products in DNAs isolated from multispecies biofilms grown in various media for various culture times. Furthermore, MLPA analyses of DNA isolated from saliva obtained from different donors gave a varying number and intensity of signals. This clearly shows the usefulness of MLPA in a quantitative description of microbial shifts.

Microstructural differences between single-species and dual-species biofilms of Streptococcus mutans and Veillonella parvula, before and after exposure to chlorhexidine.

Dual-species biofilms of Streptococcus mutans and Veillonella parvula are less susceptible to antimicrobials than single-species biofilms of the same microorganisms. The microstructure of single and dual-species biofilms of S. mutans and/or V. parvula was visualized to find out whether the spatial arrangement of bacteria in biofilms is related to survival strategies against antimicrobials. Biofilms were grown in glass-bottomed 96-well microtiter plates and exposed to chlorhexidine at 48 h. Fluorescent probes were used for staining. The microstructure of biofilms was analyzed by confocal scanning laser microscopy at 48, 96, 192, and 264 h. Spatial arrangement analysis was performed using DAIME software for 48 h biofilms. A decrease in the viability and thickness in all types of biofilms was detected after chlorhexidine treatment in time. In untreated biofilms, clustering was observed. In chlorhexidine-treated single-species biofilms, bacteria were dispersed. However, the most prominent clustering was observed in chlorhexidine-treated dual-species biofilm bacteria, which had a higher survival rate compared with chlorhexidine-treated single-species biofilms. Bacteria in dual-species biofilms establish a specific spatial arrangement, forming clusters within distances below 1.2 microm as a survival strategy against antimicrobials while the same bacteria lack this defensive construction in a single-species biofilm.

Microbial profile of dental plaque associated to white spot lesions in orthodontic patients immediately after the bracket removal.

OBJECTIVE: Denaturing Gradient Gel Electrophoresis (DGGE) is suggested to predict caries risk in young children. Such a tool would be valuable in orthodontic patients undergoing treatment with fixed appliances. In this cross-sectional study the applicability of DGGE and conventional microbiology for caries risk assessment in orthodontic patients were assessed. DESIGN: Dental plaque was obtained from orthodontic patients immediately prior to bracket removal. Presence of white spot lesions (WSL) was assessed immediately post debracketing. DGGE-patterns and band counts were assessed using varying automated band detection settings and compared to visually detected bands to determine optimum settings. Optimum settings were used to compare band patterns in subjects with or without WSL. Microbiological samples were assessed for total colony forming units (CFU's) and percentages of aciduric flora, Streptococcus mutans, Lactobacillus spp. and Candida albicans. RESULTS: Thirty-seven subjects were included with a mean age of 15.4yr (SD 1.6yr; 28 with WSL; 9 without WSL). Depending on settings, DGGE outcomes were different. Optimum minimum profiling absolute to the most intense band of 4% showed no significant difference in band numbers for subjects with or without WSL (p=0.845). Optimum settings for minimum profiling relative to the most intense band of 15% showed significant lower band numbers for subjects with WSL than those without (p=0.007). No differences between groups were observed for microbiological parameters. CONCLUSION: The analysis of DGGE-patterns is ambiguous. Software settings significantly affected outcomes. DGGE-patterns and band numbers like CFU counts were not predictive with respect to WSL formation in these orthodontic patients.

Changes in the oral ecosystem induced by the use of 8% arginine toothpaste.

OBJECTIVE: Bacterial metabolism of arginine in the oral cavity has a pH-raising and thus, potential anti-caries effect. However, the influence of arginine on the oral microbial ecosystem remains largely unresolved. DESIGN: In this pilot study, nine healthy individuals used toothpaste containing 8% arginine for eight weeks. Saliva was collected to determine arginolytic potential and sucrose metabolic activity at the Baseline, Week 4, Week 8 and after a two weeks Wash-out period. To follow the effects on microbial ecology, 16S rDNA sequencing on saliva and plaque samples at Baseline and Week 8 and metagenome sequencing on selected saliva samples of the same time-points was performed. RESULTS: During the study period, the arginolytic potential of saliva increased, while the sucrose metabolism in saliva decreased. These effects were reversed during the Wash-out period. Although a few operational taxonomic units (OTUs) in plaque changed in abundance during the study period, there was no real shift in the plaque microbiome. In the saliva microbiome there was a significant compositional shift, specifically the genus Veillonella had increased significantly in abundance at Week 8. CONCLUSION: Indeed, the presence of arginine in toothpaste affects the arginolytic capacity of saliva and reduces its sucrose metabolic activity. Additionally, it leads to a shift in the salivary microbiome composition towards a healthy ecology from a caries point of view. Therefore, arginine can be regarded as a genuine oral prebiotic.

Comparison of Composition and Anticaries Effect of Galla Chinensis Extracts with Different Isolation Methods.

OBJECTIVES: Galla chinensis water extract (GCE) has been demonstrated to inhibit dental caries by favorably shifting the demineralization/remineralization balance of enamel and inhibiting the biomass and acid formation of dental biofilm. The present study focused on the comparison of composition and anticaries effect of Galla chinensis extracts with different isolation methods, aiming to improve the efficacy of caries prevention. METHODS: The composition of water extract (GCE), ethanol extract (eGCE) and commercial tannic acid was compared. High performance liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (HPLC-ESI-TOF-MS) analysis was used to analyze the main ingredients. In vitro pH-cycling regime and polymicrobial biofilms model were used to assess the ability of different Galla chinensis extracts to inhibit enamel demineralization, acid formation and biofilm formation. RESULTS: All the GCE, eGCE and tannic acid contained a high level of total phenolics. HPLC-ESI-TOF-MS analysis showed that the main ingredients of GCE were gallic acid (GA), while eGCE mainly contained 4-7 galloylglucopyranoses (GGs) and tannic acid mainly contained 5-10 GGs. Furthermore, eGCE and tannic acid showed a better effect on inhibiting enamel demineralization, acid formation and biofilm formation compared to GCE. CONCLUSIONS: Galla chinensis extracts with higher tannin content were suggested to have higher potential to prevent dental caries.

Effect of arginine on the growth and biofilm formation of oral bacteria.

BACKGROUND: Alkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries. OBJECTIVE: To investigate the effect of arginine on the growth and biofilm formation of oral bacteria. METHODS AND RESULTS: Polymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and l-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2h and 8h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P=0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P<0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P=0.32, 0.06, 0.44 respectively). CONCLUSIONS: Arg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.