Bovine Enamel Research Articles

The effects of commercial liqueur on bovine enamel surface with incipient dental caries

The effects of commercial liqueur on bovine enamel surface with incipient dental caries

Nanosized calcium deficient hydroxyapatites for tooth enamel protection.

Calcium phosphates (CaP) are extensively studied as additives to dental care products for tooth enamel protection against caries. However, it is not clear yet whether substituted CaP could provide better enamel protection. In this study we produced, characterized and tested in vitro substituted and co‐substituted calcium deficient hydroxyapatite (CDHAp) with Sr2+ and F− ions. X‐ray powder diffractometry, Fourier transformation infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, Brunauer–Emmett–Teller were used to characterize synthesized powders and also cytotoxicity was evaluated. pH = f(t) test was performed to estimate, weather synthesized CDHAp suspensions are able to increase pH of experimental media after acid addition. Synthesis products were incorporated into paste to perform in vitro remineralization on the bovine enamel. In addition to mentioned instrumental methods, profilometry was used for evaluation of remineralised enamel samples. The obtained results confirmed formation of CDHAp substituted with 1.5–1.6 wt% of fluoride and 7.4–7.8 wt% of strontium. pH = f(t) experiment pointed out that pH increased by approximately 0.3 within 10 min after acid addition for all CDHAp suspensions. A new layer of the corresponding CDHAp was formed on the enamel. Its thickness increased by 0.8 ± 0.1 μm per day and reached up to 5.8 μm after 7 days. Additionally, octa calcium phosphates were detected on the surface of control samples. In conclusion, we can assume that CDHAp substituted with Sr2+ and/or F− could be used as an effective additive to dental care products promoting formation of protecting layer on the enamel, but there was no significant difference among sample groups.

Progression of Enamel Demineralisation Around Fissure Sealants: Optical Coherence Tomography Study.

To evaluate the progression of enamel demineralisation around fissure sealants using cross-polarisation optical coherence tomography (CP-OCT). Three fissure sealants; Fuji Triage (FJ, GC), Beautisealant (BT, Shofu) and Helioseal resin sealant (HL, Ivoclar Vivadent) were placed in cavities (3 × 0.5 × 1 mm) prepared in bovine enamel blocks (n = 5). After 7-day artificial saliva incubation, specimens were subjected to demineralisation for 4 weeks (pH 4.5). CP-OCT scans (Santec) were acquired for each specimen after 1, 2 and 4 weeks of demineralisation and lesions were quantitatively measured to analyse lesion progression. Repeated-measures ANOVA demonstrated that lesion size was statistically significantly affected by demineralisation period, fissure sealant type, and their interaction (P < 0.001). At 4 weeks, the highest mean value of lesion size was observed in HL group while FJ group showed the lowest. The rate of lesion progression was slower in FJ and statistically significantly different from BT (P < 0.05), which in turn was statistically significantly different than HL (P < 0.001). Fissure sealants that actively release ions are capable of improving the acid resistance of adjacent enamel. Beautisealant showed increased demineralisation inhibition compared to conventional resin sealant, but less than that provided by glass-ionomer sealant.

Hydroxyapatite Film Coating by Er:YAG Pulsed Laser Deposition Method for the Repair of Enamel Defects.

There are treatments available for enamel demineralization or acid erosion, but they have limitations. We aimed to manufacture a device that could directly form a hydroxyapatite (HAp) film coating on the enamel with a chairside erbium-doped yttrium aluminum garnet (Er:YAG) laser using the pulsed laser deposition (PLD) method for repairing enamel defects. We used decalcified bovine enamel specimens and compacted α-tricalcium phosphate (α-TCP) as targets of Er:YAG-PLD. With irradiation, an α-TCP coating layer was immediately deposited on the specimen surface. The morphological, mechanical, and chemical characteristics of the coatings were evaluated using scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray diffractometry (XRD), and a micro-Vickers hardness tester. Wear resistance, cell attachment of the HAp coatings, and temperature changes during the Er:YAG-PLD procedure were also observed. SEM demonstrated that the α-TCP powder turned into microparticles by irradiation. XRD peaks revealed that the coatings were almost hydrolyzed into HAp within 2 days. Micro-Vickers hardness indicated that the hardness lost by decalcification was almost recovered by the coatings. The results suggest that the Er:YAG-PLD technique is useful for repairing enamel defects and has great potential for future clinical applications.

Inhibitory effect of a gel paste containing surface pre-reacted glass-ionomer (S-PRG) filler on the cariogenicity of Streptococcus mutans

Surface pre-reacted glass-ionomer (S-PRG) filler is a bioactive functional glass that releases six different ions. Although several dental materials containing S-PRG filler have been developed, few self-care products containing S-PRG filler have been reported. We investigated the inhibitory effects of PRG gel paste containing S-PRG filler on Streptococcus mutans, a major pathogen of dental caries. PRG gel paste inhibited bacterial growth of S. mutans in a concentration-dependent manner, and all S. mutans were killed in the presence of ≥ 1% PRG gel paste. Additionally, it was difficult for S. mutans to synthesize insoluble glucan from sucrose in the presence of 0.1% PRG gel paste. A biofilm formation model was prepared in which slices of bovine enamel were infected with S. mutans after treatment with or without PRG gel paste. Biofilm formation was inhibited significantly more on the enamel treated with PRG gel paste than on enamel without PRG gel paste (P < 0.001). The inhibitory effects on bacterial growth and biofilm formation were more prominent with PRG gel paste than with S-PRG-free gel paste, suggesting that PRG gel paste may be effective as a self-care product to prevent dental caries induced by S. mutans.

Demineralisationshemmende Effekte hochfluorid- und kalziumhaltiger zahnärztlicher Lacke in Kombination mit regulär- oder hochfluoridierter Zahnpasta auf Schmelz - in vitro

Aim of the study: The aim of this in vitro study was to compare the caries preventive effect of various highly fluoride- and calcium-containing caries preventive varnishes in adjunct to use of regular or highly fluoridated toothpaste on demineralized enamel.Methods: Bovine enamel specimens (n=276) with one artificial caries lesion were randomly allocated to 12 groups. Interventions before pH-cycling were: no intervention ([N1/N5]), application of varnishes containing NaF (22,600 ppm F [ppm]; NaF1/NaF5), NaF + tricalcium phosphate (22,600 ppm; TCP1/TCP5); NaF + CPP-ACP (22,600 ppm; CPP1/CPP5); silver diamine fluoride (35,400 ppm; SDF1/SDF5), and NaF + calcium fluoride (45,200 ppm; CaF1/CaF5). During pH-cycling (28 days) half of the specimens in each group were brushed with either 1,450 (NaF; e.g., CPP1) or 5,000 ppm (NaF; e.g., CPP5) dentifrice slurry. Differences in integrated mineral loss (∆∆Z) were calculated between values after initial demineralization and after pH-cycling.Results: After pH-cycling N1 and N5 showed significantly increased ∆Z values (∆∆Z: N1: -1.997-2.851;-1.102); N5:-1.072 (-1.591;-554); p<0.05), indicating further demineralization. Additional use of all varnishes significantly decreased ∆∆Z compared to N1/N5 (p<0.05). A significant moderate correlation could be found between ΔΔZ and F concentrations of the varnishes for both regularly (rDT=0.493) and highly (rDT=0.404) fluoridated dentifrices. Between 1,450 and 5,000 ppm dentifrices, a significant difference in ∆∆Z could only be observed for N1 vs. N5 (p<0.05).Conclusion: Under the conditions chosen, all fluoride varnishes significantly reduced demineralization. Furthermore, under demineralizing a fluoride-dose response for varnishes could be observed. Thus, for children and adolescents with high caries risks varnishes containing more than 22,600 ppm should be further investigated, as they offered higher caries-preventive effects in vitro. However, the risks (e.g., fluorosis) have to be weighed against the additional anticaries effect.

The effect of in-office bleaching materials with different pH on the surface topography of bovine enamel.

This study evaluated the alterations of surface topography of the bovine enamel caused by different pH of in-office bleaching agents. 23% H2O2 with pH 5.5, 7.0 and 8.5 were applied on the bovine tooth specimens (n=10) and photo-irradiated for 10 min. The bleaching procedure was repeated three times and specimens were subjected to linear surface roughness (Ra) and Vickers microhardness test (VHN) at baseline and after three consecutive applications. The morphological alterations were observed before and after third bleaching application. Data were analyzed by two-way ANOVA followed by Tukey's HSD. The pH of the bleaching agent significantly affects the Ra and VHN (p<0.05). Low pH yielded a significant increase in Ra and decrease in VHN. All the groups showed morphological alterations and profound effect was found in pH 5.5 group. It was concluded that the pH of the bleaching agent can affect Ra, VHN and surface morphology.

Effects of the association of high fluoride- and calcium-containing caries-preventive agents with regular or high fluoride toothpaste on enamel: an in vitro study

The aim of this in vitro study was to compare the caries-preventive effect of various high fluoride- and calcium-containing caries-preventive agents (> 22.000ppm F- [ppm]) in adjunct to use of regular (1450ppm) or high (5000ppm) fluoride toothpaste on sound as well as demineralized enamel. Bovine enamel specimens (n = 276; 5mm × 3.5mm × 3mm) having one sound surface [ST] and one artificial caries lesion [DT] were randomly allocated to 12 groups. Interventions before pH-cycling were no intervention ([SC1/SC5]), application of varnishes/solutions containing NaF (22,600ppm; Duraphat [NaF1/NaF5]); NaF + tricalcium phosphate (22,600ppm; Clinpro White Varnish [TCP1/TCP5]); NaF + CPP-ACP (22,600ppm; MI Varnish [CPP1/CPP5]); silver diammine fluoride (35,400ppm; Cariestop 30%[SDF1/SDF5]); and NaF + calcium fluoride (45,200ppm; Biophat[CaF1/CaF5]). During pH-cycling (28days, 6 × 120min demineralization/day) half of the specimens in each group were brushed (10s; 2 × /day) with either 1,450 (NaF; named, e.g., TCP1) or 5,000ppm (NaF; e.g., TCP5) dentifrice slurry. Differences in integrated mineral loss (∆∆Z) and lesion depth (∆LD) were calculated between values after initial demineralization and after pH-cycling using transversal microradiography. After pH-cycling, SC1/SC5 showed significantly increased ∆ZDT/LDDT values, indicating further demineralization (p < 0.05; paired t-test). Decreased ∆ZDT values, indicating non-significant remineralization, could only be observed in CaF1/CaF5 (p > 0.05; paired t-test). Additional use of all varnishes/solutions significantly decreased ∆∆ZDT/∆∆ZST and ∆LDDT/∆LDST compared to SC1/SC5 (p < 0.05;ANCOVA). Between 1450 and 5000ppm dentifrices, a significant difference in ∆∆ZDT/∆∆ZST and ∆LDDT/∆LDST could only be observed for SC1/SC5 (p < 0.05; ANCOVA). Under the conditions chosen, all fluoride varnishes/solutions significantly reduced demineralization. Furthermore, a significant dose-response characteristic for fluoride varnishes could be revealed. However, no additional benefit could be observed, when varnishes were combined with high fluoride instead of regular fluoride dentifrices. For children and adolescents with high caries risks varnishes containing more than 22,600ppm should be further investigated, as they offered higher caries-preventive effects in vitro. Furthermore, there seems to be no difference in the demineralization-inhibitory capacity of fluoride varnishes when used in combination with either standard or highly fluoridated dentifrices.

Antimicrobial Effects of Inula viscosa Extract on the In Situ Initial Oral Biofilm

Given the undesirable side effects of commercially used mouth rinses that include chemically synthesized antimicrobial compounds such as chlorhexidine, it is essential to discover novel antimicrobial substances based on plant extracts. The aim of this study was to examine the antimicrobial effect of Inula viscosa extract on the initial microbial adhesion in the oral cavity. Individual test splints were manufactured for the participants, on which disinfected bovine enamel samples were attached. After the initial microbial adhesion, the biofilm-covered oral samples were removed and treated with different concentrations (10, 20, and 30 mg/mL) of an I. viscosa extract for 10 min. Positive and negative controls were also sampled. Regarding the microbiological parameters, the colony-forming units (CFU) and vitality testing (live/dead staining) were examined in combination with fluorescence microscopy. An I. viscosa extract with a concentration of 30 mg/mL killed the bacteria of the initial adhesion at a rate of 99.99% (log10 CFU value of 1.837 ± 1.54). Compared to the negative control, no killing effects were determined after treatment with I. viscosa extract at concentrations of 10 mg/mL (log10 CFU value 3.776 ± 0.831; median 3.776) and 20 mg/mL (log10 CFU value 3.725 ± 0.300; median 3.711). The live/dead staining revealed a significant reduction (p < 0.0001) of vital adherent bacteria after treatment with 10 mg/mL of I. viscosa extract. After treatment with an I. viscosa extract with a concentration of 30 mg/mL, no vital bacteria could be detected. For the first time, significant antimicrobial effects on the initial microbial adhesion in in situ oral biofilms were reported for an I. viscosa extract.

Combination Effect of Diurnal Exposure to Sucrose and Nocturnal Exposure to Lactose on Enamel Demineralization

We have hypothesized that the association between human milk and caries in breastfeeding children could be explained by the combination of a diurnal cariogenic diet with the nocturnal lactose fermentation, conditions simulated in this experimental study. Cariogenic biofilm was formed on bovine enamel slabs, which were exposed 8x/day for 3 min to a 10% sucrose solution, simulating a highly cariogenic diurnal diet, or 50 mM NaCl solution (control). Simulating the nocturnal retention of milk in mouth, biofilms were transferred to culture medium containing 0.7% lactose for 2 h, or only to culture medium (control). Four groups were designed (n = 12): Ctrl, no exposure to diurnal sucrose or nocturnal lactose; Lac, only nocturnal exposure to lactose (2 h); Suc, only diurnal exposure to sucrose (8x/day); and Suc→Lac, diurnal exposure to sucrose (8x/day) followed by nocturnal exposure to lactose (2 h). The medium was changed 3x/day, at the beginning of the day and after diurnal and nocturnal exposures. Calcium in the medium was determined as a chemical indicator of partial demineralizations occurred during the diurnal and the nocturnal treatments; the medium pH was also determined. After 96 h of growth, biofilms were harvested to evaluate CFU, biomass, and extracellular polysaccharides, soluble and insoluble. The percentage of enamel surface hardness loss (%SHL) was evaluated as cumulative demineralization. Data were analyzed by one-way ANOVA and Tukey’s test (α = 5%). Highest %SHL (p < 0.05) was found for the Suc→Lac (40.6%) group when compared to Suc (32.1%), Lac (6.6%), and Ctrl (2.4%) groups. Calcium released during the diurnal and nocturnal treatments was, respectively, Suc→Lac = Suc > Lac = Ctrl and Suc→Lac > Lac > Suc = Ctrl (p < 0.05). Regarding the Ctrl group, calcium released from nocturnal lactose fermentation by the Suc→Lac group was 4-fold greater than that provoked by the Lac group. The findings were supported by the pH of the media. The data suggest that the biofilm formed under diurnal exposure to sucrose enhances the cariogenicity of nocturnal exposure to lactose.

Quantifying the demineralisation of enamel using a hyperspectral camera measuring fluorescence loss

BackgroundThe gold standard for quantifying mineral loss of enamel is transverse microradiography (TMR) and is complimented by the non-destructive quantitative light induced fluorescence (QLF) which measures changes in autofluorescence. Fluorescence loss has been shown to correlate with mineral loss. Building upon the established method, the use of hyperspectral fluorescence imaging (HI) allows the capture of a broader range of wavelengths to quantify fluorescence changes more accurately. MethodsBovine Enamel was demineralised within the dual constant depth film fermenter over 14 days and analysed using TMR, QLF and HI. The mineral change values were compared using Pearson's Correlation Coefficient. ResultsThe analysis showed a statistically significant correlation that was equal between TMR and HI (r = 0.844) and TMR and QLF (r = 0.844), but weaker between QLF and HI (r = 0.811). ConclusionsThe correlations indicate that HI is a promising valid non-destructive method for quantifying mineral loss from bovine enamel that is as accurate as QLF and complements TMR.

Influence of periodic milk or cream treatment on the anti-erosive potential of the acquired enamel pellicle

ObjectiveThe purpose of the present study was to assess the anti-erosive potential of the acquired enamel pellicle formed in situ under the influence of periodic milk or cream treatment. MethodsThe pellicle was formed on bovine enamel specimens in the oral cavity at buccal and palatal sites of upper molars in 6 subjects, using removable acrylic splints. During 6-h of intraoral exposure, splints were removed from the oral cavity every 25 min, treated with milk or cream for 5 min, and subsequently re-inserted into the oral cavity. After 6 h, pellicle covered specimens were immersed in citric acid (0.1 or 1.0 %) for 1 min, and processed for measurement of surface microhardness, determination of calcium release by atomic absorption spectroscopy, scanning and transmission electron microscopy. Statistical analysis was performed with SAS. ResultsStatistical analysis did not indicate major differences between erosive surface alterations on enamel specimens covered by pellicles treated with cream or milk, and those covered by control pellicles. In addition, TEM analysis did not reveal any differences concerning the ultrastructure of the different pellicle treatments during acid exposure. All pellicles were dissolved in part after exposure to 0.1 % citric acid and were nearly completely removed after treatment with 1.0% citric acid. ConclusionsIt is concluded that periodic treatment with milk or cream during pellicle formation in situ does not improve the protective potential of the acquired enamel pellicle against erosion. Clinical significanceModification of the pellicle by consumption of milk or cream prior to an acidic challenge cannot sufficiently protect enamel from erosion.

Effect of alumina particle morphology used for air abrasion on loss of enamel and luting composite resin

ObjectiveTo evaluate the volume loss after air abrasion with alumina particles with different morphology on bovine enamel and luting composite resin. MethodsAir abrasion was performed on 12 unscathed bovine teeth and 72 luting composite resin discs with 85 μm round-shaped and 50 μm sharp-edged alumina particles applied for 20 s, 40 s and 60 s (n = 12). Air abrasion was standardized by uniform areas of 2 mm diameter, a pressure of 0.25 MPa and a distance of 3 mm. The volume loss was determined by using a laboratory scanner. ResultsAir abrasion with round-shaped alumina particles was mostly not measurable with the laboratory scanner, while sharp-edged alumina air abrasion resulted in significant loss of enamel. The median of volume loss by sharp-edged alumina particles ranged from 0.78 mm3 (20 s) to 2.52 mm3 (60 s). In contrast to round-shaped alumina the removal caused by sharp-edged alumina increased significantly with increasing application times (p ≤ 0.05). For air abrasion on luting composite resin the median of the removed volume ranged from 2.25 mm3 (20 s) to 6.18 mm3 (60 s), while round-shaped alumina showed a range from 0.45 mm3 (20 s) to 1.40mm3 (60 s). The round-shaped alumina produced a statistically significant lower volume loss than sharp-edged alumina for all three air abrasion times. SignificanceThe 85 μm round-shaped alumina particles removed less composite resin than 50 μm sharp-edged alumina particles but barely any enamel, making it an option for removing composite resin residues from enamel.

Influence of masticating cycles and chewing patterns on inadvertent enamel wear caused by zirconia brackets.

Little information is available about enamel wear caused by zirconia brackets, an inadvertent side effect of orthodontic treatment. The purpose of this study was to examine potential enamel damage induced by contact with zirconia brackets. Sliding and impact wear simulations were performed using bovine enamel specimens positioned at a 25° slant to a zirconium ball to determine wear behaviour. Different chewing patterns, tapping and grinding, were simulated. Specimens were profiled using confocal laser scanning microscopy, and the mean maximum depth and surface roughness were measured. Scanning electron microscopy was also performed. The mean maximum depth of wear values differed according to the number of mastication cycles, with a higher number of cycles producing higher depths of wear. The facet wear depth was significantly greater with the tapping pattern than with the grinding pattern. Scanning electron microscopic observation of the wear facets revealed that surface textures at the edges were rougher than those at the centre of all facets. The results of this study indicated that enamel wear was induced by contact with zirconia brackets during the early period of mastication, and that the patterns and number of cycles of mastication affected the wear progression of enamel.

Solutions and Gels Containing a Sugarcane-Derived Cystatin (CaneCPI-5) Reduce Enamel and Dentin Erosion in vitro

The effect of solutions and gels containing a sugarcane-derived cystatin (CaneCPI-5) on the protection against enamel and dentin erosion in vitro was evaluated. Bovine enamel and dentin specimens were divided into 2 groups (n = 135 and 153/group for enamel and dentin, respectively) that were treated with solutions or chitosan gels containing 0.1 or 0.25 mg/mL CaneCPI-5. The positive controls for solutions and gels were Elmex Erosion Protection™ solution and NaF gel (12,300 ppm F), respectively. Deionized water and chitosan gel served as controls, respectively. The solutions were first applied on the specimens for 1 min and the gels for 4 min. Stimulated saliva was collected from 3 donors and used to form a 2-h acquired pellicle on the specimens. Then, the specimens were submitted to an erosive pH cycling protocol 4 times/day for 7 days (0.1% citric acid pH 2.5/90 s, artificial saliva/2 h, and artificial saliva overnight). The solutions and gels were applied again during pH cycling, 2 times/day for 1 min and 4 min, respectively, after the first and last erosive challenges. Enamel and dentin losses (µm) were assessed by contact profilometry. Data were analyzed by 2-way ANOVA and Tukey’s test (p < 0.05). All the treatments significantly reduced enamel and dentin loss in comparison with controls. Both CaneCPI-5 concentrations had a similar protective effect against enamel erosion, but only the higher concentration was as effective against dentin erosion as the positive control. Regarding the vehicles, only the 0.1 mg/mL gel performed worse than the positive control for dentin. CaneCPI-5 reduced enamel and dentin erosion to a similar extent as the fluoride-containing vehicles. However, dentin requires higher CaneCPI-5 concentrations, in the case of gels. Solutions or gels containing CaneCPI-5 might be a new approach to protect against dental erosion.

The cariogenic effect of starch on oral microcosm grown within the dual constant depth film fermenter.

Evidence on the link between starch intake and caries incidence is conflicting, therefore the cariogenicity of starch compared with sucrose was explored using a dual Constant Depth Film Fermenter (dCDFF) biotic model system. Bovine enamel discs were used as a substrate and the dCDFF was inoculated using human saliva. CDFF units were supplemented with artificial saliva growth media at a constant rate to mimic resting salivary flow rate over 14 days. The CDFF units were exposed to different conditions, 2% sucrose or 2% starch 8 times daily and either no additional fluoride or 1450 ppm F- twice daily. Bovine enamel discs were removed at intervals (days 3, 7, 10 and 14) for bacterial enumeration and enamel analysis using Quantitative Light Induced Fluorescence (QLF) and Transverse Microradiography (TMR). Results showed that in the absence of fluoride there was generally no difference in mineral loss between enamel exposed to either sucrose or starch when analysed using TMR and QLF (P > 0.05). In the presence of fluoride by day 14 there was significantly more mineral loss under starch than sucrose when analysed with TMR (P < 0.05). It was confirmed that starch and sucrose are similarly cariogenic within the dCDFF in the absence of fluoride. With the aid of salivary amylase, the bacteria utilise starch to produce an acidic environment similar to that of bacteria exposed to sucrose only. In the presence of fluoride, starch was more cariogenic which may be due to the bacteria producing a more hydrophobic intercellular matrix lowering the penetration of fluoride through the biofilm. This is significant as it indicates that the focus on sugars being the primary cause of caries may need re-evaluating and an increase in focus on carbohydrates is needed as they may be similarly cariogenic as sugars if not more so.

Ultrastructural changes of bovine tooth surfaces under erosion in presence of biomimetic hydroxyapatite

Enamel and dentin are susceptible to acids from food sources leading to dental erosion, a global problem affecting millions of individuals. Particulate hydroxyapatite (HAP) on the tooth surface can influence the effects of acid attacks. Standardized bovine enamel and dentin samples with artificial saliva are used in an in vitro cyclic demineralization–remineralization protocol to analyze the structural changes experienced by tooth surfaces using high-resolution scanning electron microscopy and to evaluate the potential of a HAP-based oral care gel in the protection of teeth from erosive attacks. The interfaces between HAP particle and enamel HAP crystallites are investigated using focused ion beam preparation and transmission electron microscopy. The results show that erosion with phosphoric acid severely affects enamel crystallites and dentin tubules, while artificial saliva leads to remineralization effects. The HAP-gel forms a microscopic layer on both enamel and dentin surfaces. Upon acid exposure, this layer is sacrificed before the native tooth tissues are affected, leading to significantly lower degrees of demineralization compared to the controls. This demonstrates that the use of particulate HAP as a biomaterial in oral care formulations can help protect enamel and dentin surfaces from erosive attacks during meals using a simple and effective protection principle.

Surface Morphological Changes and Predisposition to Staining in Dental Enamel Bleached with Different Hydrogen Peroxide Concentrations

Background: The tooth bleaching treatment can cause structural changes in the surfaces of the teeth; these changes can increase the absorption of staining agents. Purpose: This study assessed surface morphological changes and predisposition to staining in dental enamel bleached with different hydrogen peroxide (HP) concentrations, with or without the use of a light source (LS). Methods: 25 bovine incisor specimens were divided into five groups (n = 5): Control- no treatment; HP35 - hydrogen peroxide 35%; HP35+LED - hydrogen peroxide 35% + light emission; HP20 - hydrogen peroxide 20%; and HP7 - hydrogen peroxide 7,5%. Twenty days after bleaching, the specimens were immersed in staining solutions four hours a day for 28 days. The morphological alterations of the bovine enamel surface were evaluated by means of scanning electron microscopy, X-ray dispersive energy spectroscopy and predisposition to the staining of the brightened enamel by means of colorimetry. Results: ANOVA with Tukey's test (p&lt;0.05) showed that HP7 had the highest ΔL values (p=0.176) (brightest), with a better lightening effect. The bleached groups exhibited morphological changes in the enamel. The groups did not exhibit significant changes in oxygen, calcium, and phosphorus values (p=0.020). The presence or absence of light was not significant (p=0.007) for the predisposition to staining in bleached teeth. Conclusion: The time of exposure to the staining solution was significant for staining bovine dental enamel. High concentrations of HP were not necessary for achieving effective bleaching. HP caused an increase in enamel porosity and depressions. The light source did not influence bleaching.

Effect of sweetener containing Stevia on the development of dental caries in enamel and dentin under a microcosm biofilm model

ObjectiveThis study compared the effect of commercial and pure sweetener containing stevia to that of aspartame, to sucrose and xylitol on the development of dental caries. Methods228 bovine enamel and root dentin were exposed to microcosm biofilm model using human saliva. From the 2nd to the 5th day, the samples were exposed daily to McBain saliva supplemented with 0.2% of the respective sweeteners/sugar, under 5% CO2 and 37 °C. The lactic acid and the colony-forming units (CFU) were quantified. The demineralization was analyzed by TMR. The data were compared statistically (Kruskal-Wallis/ Dunn, p<0.05). ResultsPure stevia, pure aspartame, xylitol and control were able to significantly reduce 92% of lactate production compared to sucrose. Stevia finn, aspartame finn and sucrose showed similar production of lactic acid (around 0.45±0.12 g/L and 0.67±0.18 g/L, for enamel and dentin, p<0.0001). With respect to total lactobacilli and S. mutans/S. sobrinus CFU, xylitol and control did not show growth on enamel, while CFU numbers were found in stevia finn, aspartame finn and sucrose groups for both tissues. Enamel and dentin demineralization was significantly reduced for xylitol, control, pure stevia and pure aspartame (85% and 83% reduction, respectively) compared to stevia finn, aspartame finn and sucrose, which in turn did not differ from each other (sucrose ΔZ: 2913.7 ± 646.7 vol%.µm for enamel and 3543.3 ± 432.5 vol%.µm for dentin). ConclusionsCommercial sweeteners containing stevia and aspartame proved to be as cariogenic as sucrose, which may be due to the other components, since the pure forms were not cariogenic. Clinical RelevanceOur study showed that some commercial sweeteners (aspartame and stevia) are as cariogenic as sucrose, which may be due to the presence of lactose. The population should be advice about the presence of lactose in such brand names, to avoid their consume.

Effects of 35% hydrogen peroxide solution containing hydrated calcium silicate on enamel surface.

The objectives of this study were to develop a novel bleaching material containing hydrated calcium silicate (hCS) particles and investigate the effects of hCS on the bleaching efficacy, microhardness, and surface morphology of bovine enamel. To prepare the hCS particles, white Portland cement was mixed with distilled water and ground into a fine powder. The particles in various proportions were then mixed with 35% hydrogen peroxide solution (HP), while HP without hCS was used as a control (HP), and teeth whitening gel was used as a commercial control (CC). Following the thrice application of experimental and control solutions on the discolored bovine enamel surface for 15min, color change (n = 10), microhardness (n = 10), and micromorphology (n = 2) of the enamel surface were analyzed. The Δ E* of the enamel surface treated with the experimental solution containing hCS was significantly higher than that of the CC, but there were no significant differences between the different hCS contents. The experimental solution containing hCS reduced the percentage of microhardness loss on the enamel surface, and the percentage of microhardness loss significantly decreased as the content of hCS increased (p < 0.05). The erosion pattern was only observed on enamel surfaces treated with HP and CC. This study suggests that HP containing hCS is effective in bleaching efficacy. In addition, hCS could also minimize the microhardness loss of tooth structure caused by HP and maintain enamel surface morphology. This novel bleaching material is promising for inhibiting demineralization and promoting the remineralization of teeth during bleaching treatment in dental clinics.