Artificial Caries Research Articles

Effect of toothpaste with nano-sized trimetaphosphate on dental caries: In situ study

ObjectivesThis in situ study was to evaluate the remineralizing effect of a fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate (TMP). MethodsThis blind and cross-over study was performed in 4 phases of 3 days each. Twelve subjects used palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned into the following treatment groups: Placebo (without F and TMP); 1100ppm F (1100), 1100 supplemented with 3% micrometric TMP (1100 TMP) and with nano-sized TMP (1100 TMPnano). Volunteers were instructed to brush their natural teeth with the palatal appliances in the mouth during 1min (3 times/day), so that blocks were treated with natural slurries of toothpastes. After each phase, the percentage of surface hardness recovery (%SHR), integrated mineral recovery (IMR) and integrated differential mineral area profile (ΔIMR) in enamel lesions were calculated. F in enamel was also determined. Data were analyzed by ANOVA and Student–Newman–Keuls test. ResultsEnamel surface became 20% harder when treated with 1100 TMPnano in comparison with 1100 (p<0.001). 1100 TMPnano showed remineralizing capacity (IMR; ΔIMR) 66% higher when compared with 1100 TMP (p<0.001). Enamel F uptake in the 1100 TMPnano group was 2-fold higher when compared to its counterpart without TMP (p<0.001). ConclusionThe addition of 3% TMPnano to a conventional toothpaste was able to promote an additional remineralizing effect of artificial caries lesions. Clinical significanceToothpaste containing 1100ppm F associated with TMPnano showed a potential of higher remineralization to 1100ppm F and 1100ppm F micrometric TMP.

Penetration of micro-filled infiltrant resins into artificial caries lesions

ObjectivesInfiltrants are non-filled low-viscosity resins that have been developed to arrest lesion progression by penetrating into the porosities of non-cavitated lesions where they are hardened and arrest lesion progression. The addition of fillers to infiltrant resin might combine the high penetrativity of the former with the better applicability of composite resins. The aim of the present study was to evaluate the penetration of different experimental micro-filled infiltrant resins (MFIRs) into artificial enamel lesions. MethodsAn infiltrant (Icon; DMG) was mixed with either one of three fillers [OF83: organic filler (83μm), OF42: organic filler (42μm) or GF0.7: glass filler (0.7μm)] reaching 35, 45 and 55% filler content, respectively. In each of 180 bovine enamel specimens three artificial lesions were created; two lesions were etched for 5s (37% H3PO4), leaving one lesion as control. Specimens were randomly allocated to 10 groups, in which either one of the MFIRs or the infiltrant was applied onto the two etched lesions for either 5s or 10s (n=18/group). Percentage of penetration (PP) was calculated and analysed. ResultsFor both application times a significant influence of filler size but not of filler concentration on PP could be revealed (p<0.05; two-way ANOVA). PP of MFIRs-OF42 was not significantly different from unfilled infiltrant but significantly higher than those of OF83 and GF0.7 (p<0.05; two-way ANOVA). ConclusionsMFIRs-OF42 showed the ability to penetrate into artificial enamel caries lesions similar to the unfilled infiltrant resin. Clinical significanceMFIRs could provide a new micro-invasive treatment for small-cavitated lesions.

Fluoride dose-response of human and bovine enamel artificial caries lesions under pH-cycling conditions.

This laboratory study aimed to (a) compare the fluoride dose-response of different caries lesions created in human and bovine enamel (HE/BE) under pH-cycling conditions and (b) investigate the suitability of Knoop and Vickers surface microhardness (K-SMH/V-SMH) in comparison to transverse microradiography (TMR) to investigate lesion de- and remineralization. Caries lesions were formed using three different protocols (Carbopol, hydroxyethylcellulose-HEC, methylcellulose-MeC) and assigned to 24 groups using V-SMH, based on a 2 (enamel types) × 3 (lesion types) × 4 (fluoride concentrations used during pH-cycling-simulating 0/250/1100/2800 ppm F as sodium fluoride dentifrices) factorial design. Changes in mineral content and structural integrity of lesions were determined before and after pH-cycling. Data were analyzed using three-way ANOVA. BE was more prone to demineralization than HE. Both enamel types showed similar responses to fluoride with BE showing more remineralization (as change in integrated mineral loss and lesion depth reduction), although differences between tissues were already present at lesion baseline. Carbopol and MeC lesions responded well to fluoride, whereas HEC lesions were almost inert. K- and V-SMH correlated well with each other and with the integrated mineral loss data, although better correlations were found for HE than for BE and for MeC than for Carbopol lesions. Hardness data for HEC lesions correlated only with surface zone mineral density data. BE is a suitable surrogate for HE under pH-cycling conditions. The in vitro modeling of dental caries is complex and requires knowledge of lesion behavior, analytical techniques, and employed hard tissues.

Remineralizing Efficacy of Fluorohydroxyapatite Gel on Artificial Dentinal Caries Lesion

The aim was to evaluate the remineralizing efficacy of fluorohydroxyapatite (FHA) gel on artificial dentinal caries lesion in vitro. Artificial carious lesions were made on occlusal cavities of teeth by exposing the dentin surface to a demineralizing solution. Each cavity was capped with a 3 mm thick FHA gel for 4 weeks. After the FHA gel was removed, the surface morphology and structure of the dentin were characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The dentin mineral density (DMD) was measured by micro‐computed tomography (Micro‐CT). A layer of dense and orderly hexagonal crystal structure, with average diameter of 1 μm and thickness of 4~5 μm, could be observed on dentin surface. These crystals exhibited elemental peaks for calcium, phosphorus, carbon, and oxygen and characteristic peaks of hydroxyapatite (HA) and fluorapatite (FA) via XRD and FT‐IR. The DMD of dentin surface layer significantly increased after it was capped with FHA gel (P &lt; 0.05). In the present study, the FHA gel could rapidly construct apatite on the artificial dentin caries surface and significantly increase the mineral density, which suggests that FHA gel might be a proper IPT material with remineralizing function.

Remineralisation Effect of Fluoride on Early Caries Lesions using a Quantitative Light-Induced Fluorescence-Digital (QLF-D)

The aim of this study was to evaluate the remineralisation effect after fluoride application onto an early caries lesion using a Quantitative Light-induced Fluorescence-Digital (QLF-D). Specimens were prepared by human posterior teeth and were embedded into a plaster cast to exposure the crown part. Specimens were divided randomly into the following three groups; (1) control group, (2) 2% NaF solution, (3) 1.23% APF gel. Artificial enamel caries were formed in specimens (demineralised area) with a 1.0% Carbopol 2050 (pH 4.8). Topical fluoride solution and gel were applied to the specimens of experimental group for 4 minutes and they were immersed in human saliva for 1 hour. Mineral loss of artificial caries lesion was evaluated by fluorescence loss (⊿F) values using QLF-D. Differences between baseline and post-treatment values in the three groups were assessed one-way ANOVA and post-hoc test was performed with the Tukey's test (SPSS 18.0). The average ⊿F values of baseline were -6.56 in three groups. ⊿F of APF gel group (1.90) is greatly decreased compared to the baseline and was statistically significant difference compared with two groups (0.12) (p < 0.05). Therefore, the 1.23% APF gel is the most effective in the treatment of remineralisation of artificial caries lesions. Also, the QLF-D could be useful for the evaluation of the remineralisation effect in early caries.

An in vitro evaluation of the demineralization inhibitory effect of F(-) varnish and casein phosphopeptide-amorphous calcium phosphate on enamel in young permanent teeth.

Aims and Objectives:To determine the demineralization inhibitory potential of fluoride varnish and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and to compare and evaluate the additive effect of fluoride varnish + CPP-ACP.Materials and Methods:Ten healthy premolar teeth that were extracted for orthodontic purposes were collected, and each tooth was longitudinally sectioned buccolingually and mesiodistally into four sections. The teeth were then assigned to four different treatment groups namely fluoride varnish, CPP-ACP, F− varnish followed by CPP-ACP and control. The prepared enamel samples were suspended in an artificial caries challenge for 10 days. The demineralizing inhibitory effects of the groups were recorded using polarized light microscopy.Statistical Analysis Used:Statistical analysis was carried out using analysis of variance and Duncan's multiple range tests.Results:The mean lesion depths of all the groups were Group 1 (fluoride varnish): 104.71, Group 2 (CPP-ACP): 127.09, Group 3: (F− varnish + CPP-ACP): 82.34, Group 4 (control): 146.93.Conclusion:Demineralization inhibitory potential on the additive use of F− varnish and casein phosphopeptide was superior to fluoride varnish or CPP-ACP applied alone on the enamel of young permanent teeth.

Artificial caries lesions model influence on the μTBS demineralized dentin/resin

Artificial caries lesions model influence on the μTBS demineralized dentin/resin

The effect of ER: YAG laser on enamel resistance to caries during orthodontic treatment: An in vitro study

Background: One common undesirable side effect of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets, particularly in patients with poor oral hygiene. Different methods have been used to prevent demineralization; the recent effort to improve the resistance against the demineralization is by the application of lasers. Materials and method: Thirty human premolars extracted for orthodontic purposes were used to test the effect of two energy level of ER-YAG laser on enamel resistance to demineralization. The brackets were bonded on the teeth and all the labial surface excluding 2 mm area gingival to the brackets were painted with acid resistance varnish. Three groups were generated. The first group was the control group (A), with no treatment was performed. In group II (B)and groups III (C); teeth were irradiated by ER-YAG laser of 200, 60 mj energy respectively. All the teeth were individually subjected to acid challenge cycle for 30 days. After debonding longitudinal sections were taken and examined under stereomicroscope. The enamel demineralization evaluation was done by taking the average of three depths at the centre of the artificial lesion. Also the enamel surface was classified by an experienced investigator according to acid etch pattern. Comparisons of the average depth values of the groups were performed with ANOVA and LSD tests. The statistical significance level was set at p ≤ 0.05. Results: The results revealed that average lesion depth was significantly deeper at the control group than the laser groups, and its significantly deeper in group (B) 200 mj than in group (C) 60 mj, enamel surfaces showed deeper pits and craters than in control group. Conclusions: the decrease in artificial caries lesion depth associated with use of the two laser energy level support the ER-YAG laser as a tool to increase enamel resistance to demineralization and white spot lesion prevention. Key words: Demineralization, ER-YAG, laser.

Inhibitive Effect of a New Dental Resin Composite on Enamel Artificial Caries

Purpose To investigate the cariostatic effect of six restorative materials in vitro. Method Enamel blocks of bovine incisors were restored with six restorative materials (a conventional GIC, FujiIILC, Compoglass F, BeautifilII,Charisma and an experimental fluoride releasing resin composite) respectively with a gap of 270μm in width between each filling material and enamel. Then all restorations were immersed in a partially saturated acidic buffer solution at 37C for 3days. The surface enamel microhardness of the enamel blocks were measured before and after demineralization and the depth of enamel demineralization was measured using polarization microscope for each restoration.Results Enamel surface hardness of all restorations demonstrated significant reduced after demineralization ( p&lt;0.05), and the order of hardness reduction is as follows: Charisma &gt;BeautifilII≈Compoglass F≈Experimental Resin&gt;FujiIILC&gt;GIC ( p&gt; 0.05). The order of the depth of enamel demineralization along the surface and the interface near the gap for the 5 materials is as follows: Charisma &gt;BeautifilII≈Compoglass F ≈Experimental Resin&gt;FujiIILC&gt;GIC (P &gt; 0.05). Conclusion The new fluoride releasing and recharging composite resin has the ability to prevent recurrent caries around the restoration and its ability is comparable to compomer materials.

Effect of a Self-Etching Adhesive System Containing a Novel Antimicrobial Polymer (QAMP) on Inhibiting Carious Lesions by Evaluating the Mechanical Properties of the Resin–Dentin Interface

The objective of this study was to assess the in vitro effect of a quaternary ammonium methacrylate polymer (QAMP) incorporated into a self-etching adhesive system on inhibiting caries by evaluating the mechanical properties of the adhesive interface. Twenty-four human third molars were distributed into: Clearfil™ SE Bond containing 5% QAMP (experimental group), Clearfil™ Protect Bond (positive control), and Clearfil™ SE Bond (negative control). Teeth of each group were divided according to the method for producing artificial caries lesions: pH-cycling or microbiological assay. All samples were sectioned and polished in order to obtain hardness (H) and Young's modulus (E) values by nanoindentation test in the hybrid layer and dentin. Data were analyzed by ANOVA and Games Howell's post hoc test (α = 0.05). Regarding the hybrid layer, Clearfil™ SE Bond containing QAMP demonstrated H and E values statistically higher than Clearfil™ SE Bond in both pH-cycling and microbiological experiments. Considering dentin, Clearfil™ SE Bond containing QAMP showed H and E values statistically higher than Clearfil™ Protect Bond and Clearfil™ SE Bond in the pH-cycling method and then Clearfil™ SE Bond concerning the microbiological method. In general, Clearfil™ SE Bond containing QAMP provided better mechanical properties for the resin–dentin interface after cariogenic challenges.

Restoration Materials and Secondary Caries Using an In Vitro Biofilm Model

This in vitro study investigated whether restoration materials and adhesives influence secondary caries formation in gaps using a short-term in vitro biofilm model. Sixty enamel–dentin blocks were restored with 6 different restoration materials with or without adhesives (n = 10 per group) with a gap: 1) Clearfil AP-X composite, 2) Clearfil AP-X composite + SE Bond, 3) Clearfil AP-X composite + ProtectBond, 4) Filtek Silorane composite, 5) Filtek Silorane composite + Silorane System adhesive, or 6) Tytin amalgam. Specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel–dentin next to the different materials was measured in lesion depth (LD) and mineral loss (ML) using transversal wavelength independent microradiography (T-WIM). A regression analysis was used to compare the LD and ML of the different restoration materials at 4 measurement locations: 1 location at the surface of the enamel, 1 location at the wall of the enamel, and 2 locations at the wall of the dentin. A statistically significant effect of AP-X composite with Protect Bond was found for LD and ML at the WallDentin1 location, leading to less advanced wall lesions. An additional finding was that gap size was also statistically significant at the 2 wall locations in dentin, leading to increasing lesion progression with wider gaps. In conclusion, adhesives can influence wall lesion development in gaps. Protect Bond showed significantly less caries progression compared to bare restoration materials or other adhesives in this short-term in vitro biofilm model.

Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in vitro

ObjectivesAnalyse the effect of varnishes containing xylitol alone or combined with fluoride on the remineralization of artificial enamel caries lesions in vitro. MethodsBovine enamel specimens were randomly allocated to 7 groups (n=15/group). Artificial caries lesions were produced by immersion in 30mL of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6μM tetraetil metil diphosphanate (pH 5.0) for 6 days. The enamel blocks were treated with the following varnishes: 10% xylitol; 20% xylitol; 10% xylitol plus F (5% NaF); 20% xylitol plus F (5% NaF); Duofluorid™ (6% NaF, 2.71% F+6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. The blocks were subjected to pH-cycles (demineralization—2h/remineralization—22h during 8 days) and enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analysed by ANOVA/Tukey's test or Kruskal–Wallis/Dunn's test (p<0.05). ResultsEnamel surface remineralization was significantly increased by Duraphat™, 10% xylitol plus F and 20% xylitol plus F formulations, while significant subsurface mineral remineralization could be seen only for enamel treated with Duraphat™, Duofluorid™ and 20% xylitol formulations. Conclusions20% xylitol varnishes seem to be promising alternatives to increase remineralization of artificial caries lesions. Clinical significance: effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in vitro, which should be confirmed by in situ and clinical studies.

Near-infrared hyperspectral imaging of water evaporation dynamics for early detection of incipient caries

ObjectivesIncipient caries is characterized as demineralization of the tooth enamel reflecting in increased porosity of enamel structure. As a result, the demineralized enamel may contain increased amount of water, and exhibit different water evaporation dynamics than the sound enamel. The objective of this paper is to assess the applicability of water evaporation dynamics of sound and demineralized enamel for detection and quantification of incipient caries using near-infrared hyperspectral imaging. MethodsThe time lapse of water evaporation from enamel samples with artificial and natural caries lesions of different stages was imaged by a near-infrared hyperspectral imaging system. Partial least squares regression was used to predict the water content from the acquired spectra. The water evaporation dynamics was characterized by a first order logarithmic drying model. The calculated time constants of the logarithmic drying model were used as the discriminative feature. ResultsThe conducted measurements showed that demineralized enamel contains more water and exhibits significantly faster water evaporation than the sound enamel. By appropriate modelling of the water evaporation process from the enamel surface, the contrast between the sound and demineralized enamel observed in the individual near infrared spectral images can be substantially enhanced. ConclusionsThe presented results indicate that near-infrared based prediction of water content combined with an appropriate drying model presents a strong foundation for development of novel diagnostic tools for incipient caries detection. Clinical SignificanceThe results of the study enhance the understanding of the water evaporation process from the sound and demineralized enamel and have significant implications for the detection of incipient caries by near-infrared hyperspectral imaging.

Dentifrice Fluoride and Abrasivity Interplay on Artificial Caries Lesions

Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 m<smlcap>M</smlcap>) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

Bonding longevity of flowable GIC layer in artificially carious dentin

PurposeTo evaluate the bond longevity of glass ionomer cement (GIC) to sound and artificially carious dentin, using a high viscosity material with regular consistency and using a flowable GIC, after one year water storage. Material and methodsSixty bovine incisors were polished to obtain flat buccal dentin. Thirty teeth were submitted to pH-cycling model to simulate artificial caries. Teeth from both dentin conditions (sound and caries) were randomly reassigned according to the powder/liquid ratio of the GIC (n=15): (1) regular (1:1) and (2) flowable GIC (1:2). Polyethylene tubes with internal diameter of 0.76mm were placed over the pre-treated dentin and filled up with GIC (KetacTM Molar Easy Mix, 3M ESPE), immediately protected with a layer of petroleum jelly. Half of the specimens were evaluated by microshear bond strength test after 24h, the other half was evaluated one year later, after water storage at 37°C. Data (MPa) were analyzed with 3-way repeated measures ANOVA and Tukey׳s post-hoc tests (α=0.05). ResultsStatistical analysis revealed reduction of GIC bonding effectiveness after one year of water storage (5.4±1.4 to 3.4±1.3MPa) (p<0.001). No significant differences were observed (p=0.126) between regular (4.2±1.8MPa) and flowable (4.6±1.5MPa) GIC consistency. Moreover, GIC showed better bonding effectiveness on sound (5.1±1.7MPa) than artificially carious dentin (3.7±1.3MPa) (p<0.001). ConclusionsBoth powder/liquid ratio of GIC show similar reduction of bonding effectiveness after one year, especially in artificially carious dentin substrate.

Wettability of chlorhexidine treated non‐carious and caries‐affected dentine

The wettability of a surface is a prerequisite for adhesion and the type of dentine plays an important role in this property. This study evaluated the effect of different excipients of chlorhexidine (CHX) on sound and caries-affected dentine wettability. Flat dentine surfaces were prepared (n = 100) and artificial caries was induced in half of the sample. For each substrate, sound and caries-affected dentine, surfaces were assigned to five groups: (1) smear-covered dentine; (2) smear-free dentine saturated with water; (3) ethanol; (4) 1% CHX in water; or (5) 1% chlorhexidine in ethanol. The infected dentine was ground with 320-grit silicon carbide paper to the level of affected dentine. The smear layer was removed with acid, followed by rinsing, blot drying and the application of each solution (60 seconds). Single Bond 2 was applied to each surface and contact angles were measured using a goniometer. Data were analysed by ANOVA and Student–Newman–Keuls (a = 0.05). Contact angles were higher on sound dentine, regardless of the treatment. For sound and caries-affected dentine significantly higher angles were obtained on smear-covered dentine. Acid-etched dentine saturated with ethanol and ethanol/CHX resulted in significantly lower angles but only for sound dentine. Neither water and water/CHX nor ethanol and ethanol/CHX solutions differ with respect to dentine wettability. Caries-affected dentine wettability is higher than sound dentine, and chlorhexidine does not influence this property.

In vitro Remineralizing Effect of Fluoride Varnishes Containing Sodium Trimetaphosphate

This study analyzed the effects of fluoride varnishes supplemented with sodium trimetaphosphate (TMP) on the remineralization of caries-like lesions in vitro. Bovine enamel discs were selected through surface hardness (SH) and caries-like lesions were induced. SH was again determined and the blocks were divided into 7 experimental groups (n = 24/group): placebo (no fluoride or TMP), 5% TMP, 2.5% NaF, 2.5% NaF/5% TMP, 5% NaF, 5% NaF/5% TMP and commercial formulation (Duraphat™, 5% NaF), following a blind protocol. Discs were treated with the varnishes and kept in a remineralizing solution for 4 h and a demineralizing solution for 2 h. Varnishes were then removed and half of the discs were used for analysis of loosely (CaF₂) and firmly bound fluoride. The remaining discs were submitted to a pH-cycling regimen for 6 days. The percentage of surface hardness recovery (%SHR), cross-sectional hardness (ΔKHN) and enamel CaF₂ and fluoride were determined. Data were analyzed by ANOVA and by Student-Newman-Keuls' test (p < 0.05). A dose-response relationship was observed between fluoride concentrations in the varnishes and %SHR. The 5% TMP varnish led to %SHR similar to that obtained for the placebo. When TMP was used in association with fluoride, however, significantly higher %SHR were observed in comparison with their counterparts without TMP. Moreover, ΔKHN obtained for the 5% NaF/5% TMP was significantly lower among all groups tested. Higher concentrations of CaF₂ and fluoride were observed for Duraphat and 5% NaF, followed by 5% NaF/5% TMP, 2.5% NaF and 2.5% NaF/5% TMP (p < 0.05). It was concluded that the supplementation of fluoride varnishes with TMP leads to enhanced remineralizing effect of artificial caries lesions in vitro.

8DSS-Promoted Remineralization of Initial Enamel Caries In Vitro

Peptides containing 8 repeats of aspartate-serine-serine (8DSS) have been shown to promote the nucleation of calcium phosphate from solution into human enamel. Here we tested the ability of 8DSS to promote the remineralization of demineralized enamel in an in vitro model of artificial early enamel caries. Initial caries lesions were created in bovine enamel blocks, which were then subjected to 12 d of pH cycling in the presence of 25 µM 8DSS, 1 g/L NaF (positive control) or buffer alone (negative control). Absorption of 8DSS was verified by X-ray photoelectron spectroscopy. Mineral loss, lesion depth, and mineral content at the surface layer and at different depths of the lesion body were analyzed before and after pH cycling by polarized light microscopy and transverse microradiography. Mineral loss after pH cycling was significantly lower in the 8DSS samples than in the buffer-only samples, and lesions in the 8DSS samples were significantly less deep. Samples treated with 8DSS showed significantly higher mineral content than buffer-only samples in the region extending from the surface layer (30 µm) to the average lesion depth (110 µm). No significant differences were found between the samples treated with 8DSS and those treated with NaF. These findings suggest that 8DSS has the potential to promote remineralization of demineralized enamel.

Evaluation of new treatment for incipient enamel demineralization using 45S5 bioglass

Bioglass 45S5 is a silica-based bioactive glass capable of depositing a layer of hydroxyl carbonate apatite on the surface of the glass when immersed in body fluids. The present paper studies a new technique for treating early human dental enamel caries lesions by using a paste composed of 45S5 bioglass and phosphoric acid. Artificial caries lesions were induced in enamel flat surfaces by means of a decalcification solution. All specimens were exposed to a brushing-abrasion challenge to test the durability of any newly formed layer resulting from the application of 45S5 bioglass paste. The specimens treated with bioglass paste showed complete coverage with a layer of brushite crystals. The brushing-abrasion challenge did not statistically affect the percentage of enamel coverage with the crystalline layer formed by the application of bioglass (p<0.05). These crystals were converted to hydroxyapatite crystals when stored in artificial saliva for 14 days. The current technique suggests the possibility of restoring incipient enamel erosive lesion with an abrasion durable layer of hydroxyapatite crystals.

Remineralizing efficacy of different calcium-phosphate and fluoride based delivery vehicles on artificial caries like enamel lesions

ObjectivesTo assess enamel remineralization of different calcium-phosphate and fluoride delivery systems. MethodsArtificial caries lesions were created on 115 extracted human molars. Specimens were assigned according to remineralizing agent into five groups: G1: Control (artificial saliva), G2: Clinpro™ white varnish, G3: Relief, G4: Tooth Mousse Plus, G5: Vanish™XT. Surface micro-hardness (SMH), surface roughness (Ra) and surface topography by scanning electron microscope (SEM) were evaluated at baseline, after demineralization, after 2 and 4 weeks remineralization and after acid challenge. ResultsDemineralized enamel showed the lowest SMH. By 2 weeks remineralization, SMH were ranked as follows: G2 (282.14±6.82)>G3 (269.37±7.25)>G5 (263.00±6.49)=G4 (251.83±8.26)>G1 (226.5±9.34). However, 4 weeks remineralization showed the following: G2 (304.09±6.65)>G3 (293.1±5.24)=G4 (285±7.29)>G5 (272.43±4.89)>G1 (233.33±9.12). By exposure to acid challenge, groups presented order of: G2 (279.71±5.99)=G3 (275.51±5.59)>G4 (262.29±6.65)>G5 (245.43±6.43)>G1 (190.27±8). Surface roughness showed the following mattress after 2 weeks remineralization: G1 (0.2488±0.0016)=G2 (0.2487±0.0007)=G3 (0.2476±0.0006)>G4 (0.2442±0.0004)>G5 (0.2396±0.0009). After 4 weeks remineralization: G1 (0.2469±0.0017)>G4 (0.244±0.0004)>G5 (0.2413±0.0008)=G3 (0.2405±0.0007)=G2 (0.2399±0.0006). After acid challenge; G1 (0.2582±0.0027)>G5 (0.2556±0.0007)>G4 (0.2484±0.0009)>G3 (0.2463±0.0007)>G2 (0.2443±0.0004). SEM revealed mineralized coating on the surfaces which resists dissolution by acid challenge at variable degrees according to remineralization regimen applied. ConclusionsRemineralizing agents containing different calcium-phosphate formulas and fluoride have increased remineralization potential compared to artificial saliva. Clinpro™ varnish presented the highest remineralization tendency with greatest resistance for acid challenge. Clinical significanceThis in vitro study imitated the application of different calcium phosphorous and fluoride based delivery vehicles to enamel tooth surfaces in the mouth. The new therapeutic techniques based on different calcium phosphate formulas containing fluoride provide a new avenue for remineralization of non-cavitated and early carious lesions.