Transverse Microradiography Research Articles

Detection of artificial enamel caries-like lesions with a blue hydroxyapatite-binding porosity probe

ObjectivesThis in vitro study investigated the ability of a blue protein-based hydroxyapatite porosity probe to selectively detect artificial enamel caries-like lesions of varying severities. MethodsArtificial caries-like lesions were formed in enamel specimens using a hydroxyethylcellulose-containing lactic acid gel for 4/12/24/72 or 168 h. One untreated group was used as a control. The probe was applied for 2 min and unbound probe rinsed off with deionized water. Surface color changes were determined spectrophotometrically (L*a*b* color space) and with digital photography. Lesions were characterized using quantitative light-induced fluorescence (QLF), Vickers surface microhardness, and transverse microradiography (TMR). Data were analyzed using one-way ANOVA. ResultsDigital photography did not reveal any discoloration in unaffected enamel. However, all lesions stained blue with color intensity positively correlated with demineralization times. The color data reflected similar trends: lesions became significantly darker (L* decreased) and bluer (b* decreased), while overall color differences (ΔE) increased significantly after probe application (4-h lesion, mean±standard deviation: ΔL*=-2.6 ± 4.1/Δb*=0.1 ± 0.8/ΔE=5.5 ± 1.3 vs. 168-h lesion: ΔL*=-17.3 ± 1.1/Δb*=-6.0 ± 0.6/ΔE=18.7 ± 1.1). TMR analysis revealed distinct differences in integrated mineral loss (ΔZ) and lesion depth (L) between demineralization times (4-h lesion: ΔZ=391±190 vol%min × µm/L = 18.1 ± 10.9 µm vs. 168-h lesion: ΔZ=3606±499 vol%min × µm/L = 111.9 ± 13.9 µm). QLF and microhardness were also able to differentiate between demineralization times. L and ΔZ strongly correlated (Pearson correlation coefficient [r]) with Δb* (L vs. Δb*: r=-0.90/ΔZ vs. Δb*: r=-0.90), ΔE (r = 0.85/r = 0.81), and ΔL* (r=-0.79/r=-0.73). ConclusionConsidering the limitations of this study, the blue protein-based hydroxyapatite-binding porosity probe appears to be sufficiently sensitive to distinguish between unaffected enamel and artificial caries-like lesions. Clinical significanceEarly detection of enamel caries lesions remains one of the most critical aspects in the diagnosis and management of dental caries. This study highlighted the potential of a novel porosity probe in detecting artificial caries-like demineralization by objective means.

Disaggregated Nano-Hydroxyapatite (DnHAP) with Inhibitory Effects on Biofilms and Demineralization

Nano-hydroxyapatite (nHAP) is considered a biocompatible agent that promotes the remineralization of dental hard tissue; however, its antibacterial efficacy is under scientific discussion. Therefore, this investigation aimed to specify the inhibitory effects of disaggregated nano-hydroxyapatite (DnHAP) on regrown biofilms and demineralization. Regrown biofilm models of single-species (Streptococcus mutans), dual-species (S. mutans and Candida albicans), and saliva-derived microcosm biofilms were established in vitro. Repeat treatment with DnHAP was applied to biofilms. The viability, lactic acid, biofilm structure, biomass, the inhibitory effect of demineralization, and virulence factors’ expression were determined. In addition, the biofilm microbial community was analyzed by 16S ribosomal RNA gene sequencing. DnHAP inhibited metabolism, lactic acid production, biomass, and water-insoluble polysaccharide production (P < 0.05) of regrown single/dual-species biofilms. Concerning the saliva-derived biofilms, samples treated with DnHAP showed lower biofilm metabolic activity without significant differences from samples treated with sterile deionized water (P > 0.05); in addition, saliva-derived biofilms treated with DnHAP exhibited lower lactic acid production (P < 0.05). The demineralization of bovine enamel was the lowest in the DnHAP group, as detected by transverse microradiography, and the lesion depth and volume decreased significantly (P < 0.05). The application of DnHAP did not change the diversity of regrown saliva-derived microcosm biofilms. In conclusion, this investigation showed that DnHAP could be a promising solution for the management of regrown biofilms to combat dental caries.

Effect of experimental toothpaste containing hydroxyapatite nanoparticles and propolis, with and without fluoride, on the microcosm biofilm and enamel demineralization

This study evaluated the antimicrobial and anticaries effects of toothpaste containing hydroxyapatite nanoparticles (nanoHAP − 5 or 10%), xylitol (2 or 3%) and propolis (1 or 2%), associated or not with 1500 ppm fluoride (F). An in vitro model was used with microcosm biofilm produced from a pool of human saliva and McBain saliva (1:50) in the first 8 h of culture on 162 bovine enamel specimens. At the end of the experimental period, analyses of metabolic activity, colony forming units (CFU) and transverse microradiography (TMR) were performed. This study showed a possible decrease in demineralization and increase in remineralization by the commercial toothpaste (1500 ppm F) and for the experimental toothpaste containing the highest concentration of all agents, combined with F. In addition, a reduction in antimicrobial activity possibly caused by propolis and xylitol, mainly in relation to cariogenic bacteria, was observed.

The remineralization effect of GERM CLEAN on early human enamel caries lesions in vitro

This study aimed to evaluate the remineralization effect of GERM CLEAN, a novel antibacterial peptide, on early enamel caries. Thirty human enamel blocks from thirty teeth were randomly divided into three groups: double distilled water (DDW group), GERM CLEAN (GC group), and 1000 ppm fluoride (NaF group). Specimens were demineralized for 3 days (pH 4.6) followed by pH cycling twice daily for 14 days. For a pH cycle, specimens received corresponding treatments for 5 min, then were immersed in demineralizing solution for 1 h, received corresponding treatments again, and finally were immersed in remineralizing solution (pH 7.0) for approximately 11 h. Specimens were washed with DDW after each treatment. Microindentation tests, atomic force microscopy (AFM), and transverse micro-radiography (TMR) were conducted to analyze enamel blocks. GC demonstrated a lower percentage of surface microhardness recovery (SMHR%) (p < 0.0001), rougher surfaces (p < 0.0001), deeper lesion depth (p = 0.001), and more mineral loss (p = 0.001) than NaF, but showed higher SMHR% (p < 0.0001), smoother surfaces (p < 0.0001), shallower lesion depth (p = 0.049), and less mineral loss (p = 0.001) than DDW. As a result, GERM CLEAN has the potential to promote the remineralization of demineralized enamel.

Evaluation of an Artificial Mouth for Dental Caries Development.

This study validated a microbial caries model (artificial mouth) for dental caries development to determine the optimal time to create early caries suitable for evaluation of the efficacy of caries therapeutic agents. In all, 40 human enamel blocks were placed in an artificial mouth at 37 °C and 5% CO2 and were exposed to brain heart infusion broth inoculated with S. mutans in continuous circulation (0.3 mL/min). The culture medium was replaced three times daily. Samples were exposed to 10% sucrose for 3 min, 3 times daily to promote biofilm growth. Five samples were harvested from the chamber after 3, 4, 5, 6, 7, 14, 21, and 28 days. At the end of experiment, samples were assessed visually by ICDAS criteria, while lesion depth (LD) and mineral loss (ML) were measured using polarizing light microscopy and transverse microradiography. Data were analyzed by Pearson correlation, ANOVA, and Tukey comparison test (p < 0.05). Results showed significant and strong positive correlation (p < 0.01) between all variables and biofilm growth time. LD and ML profiles of 7-day lesions seem to be the most suitable for remineralization studies. In conclusion, using the evaluated artificial mouth, early-stage caries suitable for products' evaluation studies was produced within 7 days of exposure to microbial biofilm.

Effect of whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge.

To investigate the effect of fluoride-containing whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge. Bovine enamel specimens (n = 120) with three areas [non-treated sound enamel (NSE), treated sound enamel (TSE), and treated artificial caries lesion (TACL)] were randomly assigned to the four groups: whitening mouthrinse (WM: 2.5% hydrogen peroxide-100ppm F-), placebo mouthrinse (PM: 0% hydrogen peroxide-100ppm F-), whitening gel (WG: 10% carbamide peroxide-1130ppm F-), and deionized water (negative control; NC). The treatments (2min for WM, PM, and NC, and 2h for WG) were carried out during a 28-day pH-cycling model (6 × 60min demineralization/day). Relative surface reflection intensity (rSRI) and transversal microradiography (TMR) analyses were performed. Fluoride uptake (surface and subsurface) was measured in additional enamel specimens. For TSE, a higher value of rSRI was observed in WM (89.99% ± 6.94), and a greater decrease in rSRI was observed for WG and NC, and no sign of mineral loss was verified for all groups (p > 0.05). For TACL, rSRI significantly decreased after pH-cycling for all experimental groups with no difference between them (p < 0.05). Higher amounts of fluoride were found in WG. WG and WM exhibited intermediate values of mineral loss, similar to PM. The whitening products did not potentialize the enamel demineralization under a severe cariogenic challenge, and they did not exacerbate mineral loss of the artificial caries lesions. Low concentrated hydrogen peroxide whitening gel and mouthrinse containing fluoride do not intensify the progression of caries lesions.

Prevention of Root Caries Using Oxalic Acid

Certain dentin hypersensitivity treatment materials include oxalic acid to coat dentin surfaces with minerals, while certain organic acids possess a remineralization effect. Herein, an organic acid that inhibits the demineralization and coating of root surfaces was evaluated. Specimens were produced using five non-carious extracted bovines. Four different acids were used: oxalic acid (OA), malonic acid (MA), polyacrylic acid (PA), and succinic acid (SA). Each acid was applied to the root surface and washed using distilled water or a remineralization solution, and the surface was observed using scanning electron microscopy (SEM). All the surfaces of each specimen, barring the polished surface, were covered with wax and immersed in an automatic pH cycling system for two weeks. Dentin demineralization was analyzed using transverse microradiography (TMR) before and after pH cycling. SEM analysis demonstrated that the three acid groups demineralized the dentin surface, whereas the OA group generated crystals covering the dentin surface, even in a distilled water environment. TMR analysis revealed that the OA groups showed significantly lower integrated mineral loss compared with the other groups, even in the distilled water environment. The results suggest that OA generates insoluble calcium oxalate crystals on the dentin and suppresses demineralization even under low saliva conditions.

Transverse Microradiography Evidence on the Effect of Phosphoryl Oligosaccharides of Calcium (POs-Ca) in Toothpaste on Decalcified Enamel

In the current study, we sought to evaluate the effects of phosphoryl-oligosaccharides of calcium (POs-Ca) and/or fluoride-containing toothpaste on enamel. Six groups of experimental toothpaste were prepared by adding various concentrations of POs-Ca and/or fluoride. A 5 × 10-mm window on the enamel of the bovine incisor was immersed in resin and divided into three areas for “sound”, “demineralized (DEM)”, and “after pH cycle (aft. pH cycle)”. All specimens were subjected to pH cycling, including soaking in a slurry with toothpaste diluted threefold for 5 min. Transverse microradiography was employed to evaluate the mineral recovery, and the pH values of each demineralization solution were measured. The high fluoride concentration group showed a significantly better mineral recovery rate than the others, with no statistical differences between before and after pH cycling among the POs-Ca with low fluoride, POs-Ca only, low fluoride only, and control groups. In the low-concentration fluoride groups, the group containing POs-Ca tended to have a higher remineralization effect than the non-POs-Ca group. After pH cycling, the demineralization solution showed no pH changes in any group. The addition of POs-Ca and fluoride to toothpaste may recover the mineral density in enamel subsurface lesions at low-fluoride concentrations, but the high-fluoride concentrations did not show a meaningful difference in the two groups with and without POs-Ca.

Comparative Efficacy of Novel Biomimetic Remineralising Technologies.

Biomimetic technologies for the remineralisation of enamel subsurface lesions (ESLs) have been developed and include: fluorocalcium phosphosilicate bioglass (BG/F); casein phosphopeptide-amorphous calcium phosphate (CPP−ACP) and with fluoride (CPP−ACFP); and self-assembling oligopeptide P11-4 (SAP). The aim of this study was to compare the remineralisation of ESLs in vitro using these technologies. Human enamel slabs with ESLs were cut into two half-slabs; one half-slab was untreated (control), and the other half was treated by exposure to one of the four technologies with artificial saliva (AS) or AS alone for 14 days at 37 °C. The technologies were applied to the ESL surface according to the manufacturer’s instructions. At the completion of each treatment, the treated half-slabs and their paired control half-slabs were embedded, sectioned and the mineral content was determined using transverse microradiography. The change in mineral content (remineralisation) between treatments was statistically analysed using one-way ANOVA. The order from highest to lowest remineralisation was CPP−ACFP (52.6 ± 2.6%) > CPP−ACP (43.0 ± 4.9%) > BG/F (13.2 ± 2.5%) > SAP (5.8 ± 1.6%) > AS (2.1 ± 0.5%). Only CPP−ACFP and CPP−ACP produced remineralisation throughout the body of the lesions. All four biomimetic technologies had some effect on the remineralisation of ESLs; however, CPP−ACFP with calcium, phosphate and fluoride ions stabilised by CPP was superior in the level and pattern of remineralisation obtained.

Effect of anaerobic or/and microaerophilic atmosphere on microcosm biofilm formation and tooth demineralization.

Microcosm biofilms can reproduce the complexity of a dental biofilm. However, different forms of cultivation have been used. The impact of the culture atmosphere on the development of microcosm biofilms and their potential to cause tooth demineralization has not yet been deeply studied. This study analyzes the effects of three experimental cultivation models (microaerophile vs. anaerobiosis vs. experimental mixed) on the colony-forming units (CFU) of the cariogenic microorganisms and tooth demineralization. 90 bovine enamel and 90 dentin specimens were distributed into different atmospheres: 1) microaerophilia (5 days, 5% CO2); 2) anaerobiosis (5 days, jar); 3) mixed (2 days microaerophilia and 3 days anaerobiosis), which were treated with 0.12% chlorhexidine (positive control - CHX) or Phosphate-Buffered Saline (negative control - PBS) (n=15). Human saliva and McBain's saliva containing 0.2% sucrose were used for microcosm biofilm formation, for 5 days. From the second day to the end of the experiment, the specimens were treated with CHX or PBS (1x1 min/day). Colony-forming units (CFU) were counted, and tooth demineralization was analyzed using transverse microradiography (TMR). Data were subjected to two-way ANOVA and Tukey's or Sidak's test (p<0.05). CHX was able to reduce total microorganism's CFU compared to PBS (differences of 0.3-1.48 log10 CFU/mL), except for anaerobiosis and microaerophilia in enamel and dentin biofilm, respectively. In the case of dentin, no effect of CHX on Lactobacillus spp. was observed. CHX significantly reduced enamel demineralization compared to PBS (78% and 22% reductions for enamel and dentin, respectively). Enamel mineral loss did not differ when compared with the other atmospheres; however, the enamel lesion depth was greater under anaerobiosis. Dentin mineral loss was lower under anaerobiosis when compared with the other atmospheres. The type of atmosphere has, in general, little influence on the cariogenic ability of the microcosm biofilm.

Effects of silver diamine fluoride on demineralization protection after a secondary acid challenge.

This investigation describes the effects of 5% sodium fluoride varnish and 38% silver diamine fluoride on demineralization protection of human enamel lesions of three different severities after a secondary acid challenge. Specimens underwent color and enamel surface microhardness change measurements after demineralization and treatment events. Transverse microradiography was conducted following the secondary demineralization. After treatments, enamel surface microhardness change showed that 24-hour lesions treated with fluoride varnish had less rehardening than 24-hour lesions treated with silver diamine fluoride (p<0.05), whereas 144-hour lesions from both treatment groups showed a beneficial decrease in surface microhardness change that was markedly better in samples treated with silver diamine fluoride (p<0.05). After the secondary demineralization, 24- and 144-hour lesions treated with silver diamine fluoride showed a sustained beneficial decrease in enamel surface microhardness change when compared to fluoride varnish-treated samples of the corresponding lesion severity (p<0.05). Transverse microradiography showed no difference between fluoride varnish- and silver diamine fluoride-treated samples of any corresponding lesion severity, indicating that remineralization in both fluoride varnish- and silver diamine fluoride-treated samples was proportional to each other after a secondary acid challenge. Using silver diamine fluoride may have comparable benefits to fluoride varnish in mineral loss prevention.

Inhibition of Demineralization of Dentin by Fluoride-Containing Hydrogel Desensitizers: An In Vitro Study.

Several desensitizers routinely used clinically for dentin hypersensitivity are expected to inhibit demineralization. This study aimed to evaluate the effectiveness of sealing materials in inhibiting demineralization and increasing fluorine (F) uptake by acid-treated root surfaces. Five noncarious extracted human teeth were used to produce specimens. Three different fluoride-containing materials, namely "MS Coat F" (MS), "MS Coat Hys Block Gel" (HS), and CTX2 Varnish (FV), were used herein. Each material was applied to the demineralized root surface. Single sections were obtained from each specimen. All surfaces of each specimen, except the polished surface, were covered with wax and immersed in an automatic pH cycling system for 2 weeks. Fluorine and calcium distributions in the carious lesions of each specimen were evaluated using proton-induced gamma emission (PIGE) and X-ray (PIXE) techniques, respectively. Dentin demineralization was analyzed using transverse microradiography (TMR) before and after pH cycling. µPIXE/PIGE analysis demonstrated that all sample groups showed increased fluoride uptake on the root surface. TMR analysis revealed that both HS and FV showed significantly lower integrated mineral loss values than the control group. All three samples demonstrated a tendency towards increased fluoride uptake from fluoride-containing hypersensitivity desensitizers and a demineralization inhibition effect on root dentin.

Combined Treatment with Fluoride and Antimicrobial Peptide GH12 Efficiently Controls Caries in vitro and in vivo

Combining fluoride and antimicrobial agents enhances regulation of acid and exopolysaccharide production by biofilms. The combination also weakens the acidogenic and aciduric bacteria that contribute to caries, achieving stronger caries-controlling effects with lower concentrations of fluoride. In previous studies, antimicrobial peptide GH12 has been shown to inhibit lactic acid and exopolysaccharide synthesis in various cariogenic biofilm models, and reduce the proportion of acidogenic bacteria and Keyes caries scores in a rat caries model. The current study aimed to elucidate the effect of a combination of low concentrations of sodium fluoride (NaF) and GH12 and to determine the mechanism by which GH12/NaF combination controls caries. The GH12/NaF combination contained 8 mg/L GH12 and 250 ppm NaF. A rat caries model was built, and rat dental plaque was sampled and cultivated on bovine enamel slabs in vitro and subjected to short-term treatment (5 min, 3 times/day). The caries-controlling effects were evaluated using Keyes scoring and transverse microradiography. The results showed that the GH12/NaF combination significantly decreased the onset and development of dental caries, as well as mineral content loss and lesion depth in vitro (p < 0.05). For the caries-controlling mechanisms, 16S rRNA sequencing of in vivo dental plaque revealed that populations of commensal bacteria Rothia spp. and Streptococcus parasanguinis increased in the GH12/NaF group. In contrast, Veillonella, Lactobacillus, and Streptococcus mutans decreased. Furthermore, the GH12/NaF combination significantly reduced biomass, lactic acid, and exopolysaccharides production of in vitro biofilm (p < 0.05). Overall, fluoride and GH12 efficiently arrested caries development and demineralization by regulating the microbiota and suppressing acid and exopolysaccharide production in biofilms.

Effects of a Novel, Intelligent, pH-Responsive Resin Adhesive on Cariogenic Biofilms In Vitro.

Background: Secondary caries often result in a high failure rate of resin composite restoration. Herein, we studied the dodecylmethylaminoethyl methacrylate–modified resin adhesive (DMAEM@RA) to investigate its pH-responsive antimicrobial effect on Streptococcus mutans and Candida albicans dual-species biofilms and on secondary caries. Methods: Firstly, the pH-responsive antimicrobial experiments including colony-forming units, scanning electron microscopy and exopoly-saccharide staining were measured. Secondly, lactic acid measurement and transverse microradiography analysis were performed to determine the preventive effect of DMAEM@RA on secondary caries. Lastly, quantitative real-time PCR was applied to investigate the antimicrobial effect of DMAEM@RA on cariogenic virulence genes. Results: DMAEM@RA significantly inhibited the growth, EPS, and acid production of Streptococcus mutans and Candida albicans dual-species biofilms under acidic environments (p < 0.05). Moreover, at pH 5 and 5.5, DMAEM@RA remarkably decreased the mineral loss and lesion depth of tooth hard tissue (p < 0.05) and down-regulated the expression of cariogenic genes, virulence-associated genes, and pH-regulated genes of dual-species biofilms (p < 0.05). Conclusions: DMAEM@RA played an antibiofilm role on Streptococcus mutans and Candida albicans dual-species biofilms, prevented the demineralization process, and attenuated cariogenic virulence in a pH-dependent manner.

Quantitative Assessment Methods of Early Enamel Caries with Optical Coherence Tomography: A Review

Early detection of caries is an urgent problem in the dental clinic. Current caries detection methods do not detect early enamel caries accurately, and do not show microstructural changes in the teeth. Optical coherence tomography (OCT) can provide imaging of tiny, demineralized regions of teeth in real time and noninvasively detect dynamic changes in lesions with high resolution and high sensitivity. Over the last 20 years, researchers have investigated different methods for quantitative assessment of early caries using OCT. This review provides an overview of the principles of enamel caries detection with OCT, the methods of characterizing caries lesion severity, and correlations between OCT results and measurements from multiple histological detection techniques. Studies have shown the feasibility of OCT in quantitative assessment of early enamel lesions but they vary widely in approaches. Only integrated reflectivity and refractive index measured by OCT have proven to have strong correlations with mineral loss calculated by digital microradiography or transverse microradiography. OCT has great potential to be a standard inspection method for enamel lesions, but a consensus on quantitative methods and indicators is an important prerequisite. Our review provides a basis for future discussions.

Dual-functional adhesive containing amorphous calcium phosphate nanoparticles and dimethylaminohexadecyl methacrylate promoted enamel remineralization in a biofilm-challenged environment

ObjectiveThe cariogenic biofilm on enamel, restoration, and bonding interface is closely related to dental caries and composite restoration failure. Enamel remineralization at adhesive interface is conducive to protecting bonding interface and inhibiting secondary caries. This study intended to assess the remineralization efficiency of adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) on initial caries lesion of biofilm-coated enamel. MethodsArtificial initial carious lesion was created via 72-hour immersion in demineralization solution and cariogenic biofilm was formed after 24-hour culture of Streptococcus mutans (S. mutans). Specimens were then divided into 4 groups: enamel control, enamel treated with NACP, DMAHDM and NACP+DMAHDM respectively. Samples next underwent 7-day cycling, 4 h in BHIS (brain heart infusion broth containing 1 % sucrose) and 20 h in AS (artificial saliva) per day. The pH of BHIS was tested daily. So did the concentration of calcium and phosphate in BHIS and AS. Live/dead staining, colony-forming unit (CFU) count, and lactic acid production of biofilms were measured 7 days later. The enamel remineralization efficiency was evaluated by microhardness testing and transverse microradiography (TMR) quantitatively. ResultsEnamel of NACP+DMAHDM group demonstrated excellent remineralization effectiveness. And the NACP+DMAHDM adhesive released a great number of Ca2+ and PO43- ions, increased pH to 5.81 via acid neutralization, decreased production of lactic acid, and reduced CFU count of S. mutans (P < 0.05). SignificanceThe NACP+DMAHDM adhesive would be applicable to preventing secondary caries, strengthening enamel-adhesive interface, and extending the lifespan of composite restoration.

Evaluation of the mineral-promoting effects of in-office bleaching on experimental subsurface enamel lesions

The aim of this study was to investigate the mineral-promoting effects of in-office bleaching agent on enamel subsurface lesions. Enamel subsurface lesions were divided into following groups; D: demineralized samples without any further treatment, DS: samples were further immersed in fresh saliva, DSR: samples were immersed in saliva followed by remineralization buffer, and DSBR: samples were immersed in saliva, subjected to in-office bleaching, and then immersed in remineralization buffer. The control group (CONT) consisted of untreated enamel specimens. Transverse microradiography showed that integrated mineral loss was significantly lower in the DSBR group than in the DSR group. Confocal laser Raman analysis revealed that ν1 phosphate peak height of 959 cm-1 and mineral to matrix ratio of peak heights 959 cm-1 to 1,610 cm-1 in the DSBR group were similar to those in the CONT. In-office bleaching can promote enamel remineralization by altering or removing proteins infiltrated to enamel subsurface lesions.

Comparison of calcium-based technologies to remineralise enamel subsurface lesions using microradiography and microhardness

Assessment of enamel subsurface lesion remineralisation is essential for the evaluation of novel remineralisation technologies. The gold standard to assess subsurface mineral gain of enamel lesions is transverse microradiography (TMR). However, some studies have utilised surface microhardness (SMH) to evaluate efficacy of remineralisation agents. The aim of this study was to assess remineralisation of enamel subsurface lesions using TMR and SMH after in vitro treatment with calcium-containing technologies, and to test correlation between the TMR and SMH measurements. The parameters obtained from the TMR and SMH analyses of enamel subsurface remineralisation were not significantly correlated. Furthermore, the enamel subsurface remineralisation as measured by TMR was significantly correlated with the water-soluble calcium concentration of the remineralisation products. Scanning electron microscopy revealed surface precipitates formed by specific remineralisation treatments obfuscated accurate assessment of remineralisation by SMH. It was concluded that TMR is a more appropriate method for analysis of enamel subsurface remineralisation, and that SMH values of remineralised enamel should be interpreted with caution. Using TMR the level of remineralisation (%R) by the different technologies was CPP-ACP/F (31.3 ± 1.4%); CPP-ACP (24.2 ± 1.4%); CaSO4/K2HPO4/F (21.3 ± 1.4%); f-TCP/F (20.9 ± 1.0%); Nano-HA/F (16.3 ± 0.3%); Nano-HA (15.3 ± 0.6%) and F alone control (15.4 ± 1.3%).

Effect of high-fluoride dentifrice on root dentine and bacterial composition in a multispecies biofilm model

The present study evaluated the effect of high-fluoride dentifrice on dentine demineralization and bacterial composition in a multispecies biofilm model in vitro. A seven-organism bacterial consortium was grown on bovine dentine discs in a high-throughput active attachment model. The biofilms were submitted twice per day to the following dentifrices treatments: 5,000 ppm F, 1,100 ppm F, with placebo as a negative control. After 5 days of biofilm growth, dentine samples were assessed by transversal microradiography, the biofilm was collected for bacterial counts and the pH of the media was determined. Lower integrated mineral loss values were observed when 5,000 ppm F-treatment was used compared to the other treatments. Overall microbiological counts decreased with increasing F-concentration as well the pH of the media throughout the experiment. The 5,000 ppm F-treatment caused a shift in microbial composition and reduced dentine demineralization in the in-vitro experimental model.

The Effect of Toothpastes Containing Natural Extracts on Bacterial Species of a Microcosm Biofilm and on Enamel Caries Development.

This study investigated the effects of herbal toothpaste on bacterial counts and enamel demineralization. Thirty-six bovine enamel samples were exposed to a microcosm biofilm using human saliva and McBain saliva (0.2% sucrose) for 5 days at 37 °C and first incubated anaerobically, then aerobically–capnophilically. The following experimental toothpaste slurries (2 × 2 min/day) were applied: (1) Vochysia tucanorum (10 mg/g); (2) Myrcia bella (5 mg/g); (3) Matricaria chamomilla (80 mg/g); (4) Myrrha and propolis toothpaste (commercial); (5) fluoride (F) and triclosan (1450 ppm F), 0.3% triclosan and sorbitol (Colgate®, positive control); (6) placebo (negative control). The pH of the medium was measured, bacteria were analyzed using quantitative polymerase chain reaction, and enamel demineralization was quantified using transverse microradiography. The total bacterial count was reduced by toothpaste containing Myrcia bella, Matricaria chamomilla, fluoride, and triclosan (commercial) compared to the placebo. As far as assessable, Myrcia bella, Matricaria chamomilla, and Myrrha and propolis (commercial) inhibited the outgrowth of S. mutans, while Lactobacillus spp. were reduced/eliminated by all toothpastes except Vochysia tucanorum. Mineral loss and lesion depth were significantly reduced by all toothpastes (total: 1423.6 ± 115.2 vol% × μm; 57.3 ± 9.8 μm) compared to the placebo (2420.0 ± 626.0 vol% × μm; 108.9 ± 21.17 μm). Herbal toothpastes were able to reduce enamel demineralization.