Enamel Blocks Research Articles

Evaluation of experimental resin infiltrant containing nanohydroxyapatite on color stability and microhardness in demineralized enamel.

The aim of the study was to evaluate the effect of the addition of 10% nanohydroxyapatite in an experimental resin infiltrant on color stability and mineral loss. Bovine enamel blocks were randomized into five groups (n = 27/group): SE (sound enamel); ICL (initial caries lesion); I (Icon®); E (experimental infiltrant); EH (experimental infiltrant containing 10% nanohydroxyapatite). Color evaluation (n = 15) was performed and CIEL*a*b* values were obtained at points T0 (baseline), T1 (14days immersed on coffee solution), and T2 (28days immersed) and data were calculated ∆E00, ∆WID, ∆L*, ∆a*, and ∆b*. Cross-sectional microhardness (n = 12) was performed and lesion area (∆S) was calculated. Images were obtained with polarized light optical microscopy at 40 × magnification (n = 5). In color stability results, there was significant difference between time (14 and 28days); ICL demonstrated significant difference among treated groups in all measures (∆L*, ∆a*, ∆b*, ∆E00, ∆WID) regardless of time; I and E demonstrated similar behavior on those measures and EH differed from I in ∆L*. For ∆S, ICL group showed a significant difference compared to I and EH groups, but did not differ from E. The nanohydroxyapatite incorporation suggested an effective mineral recovery on initial caries lesion in depth; however, it showed high color variation, such as Icon. In terms of ∆S, I and EH had lower mineral loss, suggesting a reinforcement on initial caries lesion. Commercial and experimental infiltrants containing nanohydroxyapatite present low color stability and might reinforce mineral in initial caries lesion.

Effect of the association of microparticles and nano-sized β-calcium glycerophosphate in conventional toothpaste on enamel remineralization: In situ study

ObjectivesThis in situ study aimed to assess the remineralizing effect of a fluoride toothpaste supplemented with β-calcium glycerophosphate in both micro (β-CaGPm) and nano-sized forms (β-CaGPn). MethodsThis blind and cross-over study was performed in 4 phases, each spanning 3 days. Twelve volunteers utilized palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned to the following treatment groups: Placebo (no F-β-CaGPm-β-CaGPn); 1100 ppm F alone (1100F); 1100F plus 0.5% micrometric β-CaGP (1100F-0.5%β-CaGPm); and 1100F plus 0.25%nano-sized β-CaGP (1100F-0.25%β-CaGPn). Participants were instructed to brush their natural teeth with the palatal appliances in the mouth for 1 min (3 times/day), ensuring that the enamel blocks were exposed to the natural toothpaste slurries. Following each phase, evaluations were conducted to determine the percentage of surface hardness recovery (%SHR), integrated recovery of subsurface hardness (ΔIHR), profile subsurface lesion through polarized light microscopy (PLM), as well as fluoride (F), calcium (Ca), and phosphorus (P) concentrations within the enamel. Data were analyzed by ANOVA and Student-Newman-Keuls test (p < 0.001). ResultsTreatment with 1100F-0.25%β-CaGPn resulted in %SHR ∼69 % and ∼40 % higher when compared to 1100F and 1100F-0.5%β-CaGPm (p < 0.001). The reduction in lesion body (ΔIHR; PLM) was ∼40 % higher with 1100F-0.25%β-CaGPn (p < 0.001) compared to 1100F. The addition of β-CaGPm and β-CaGPn did not influence enamel F concentration (p > 0.001). Treatment with 1100F-0.25%β-CaGPn led to an increase in the concentration of Ca and P in the enamel (p < 0.001). ConclusionThe addition of 0.25%β-CaGPn into 1100F formulation increased the bioavailability of calcium and phosphate, promoting a higher remineralizing effect. Clinical significanceToothpaste containing 1100F-0.25%β-CaGPn showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric β-CaGP could be a strategy for patients at caries activity.

Preparation and characterization of NaF/Chitosan supramolecular complex and their effects on prevention of enamel demineralization

Fluoridated mouthrinse is indicated for individuals with high risk of caries. Chitosan (Chit) exhibits antibacterial properties, but little is known about its effects on enamel when combined with sodium fluoride (NaF) to form NaF/Chit supramolecular complexes. In our study, NaF/Chit supramolecular complexes structured as microparticles were synthetized and characterized, and their effects on human enamel were evaluated after cariogenic challenge simulating the daily mouthrinse use. Initially, NaF/Chit complex formation was investigated based on several titrations by measuring the zeta potential, electrical conductivity (κ), hydrodynamic diameter (Dh), viscosity (η) and heat flow (by isothermal titration calorimetry) against the molar ratio [NaF]/[Chitmonomer], which allowed us to identify the interactions between Chit-NaF with a stoichiometry of approximately 0.68. Spontaneous microparticle formation was observed. Samples of enamel blocks were prepared and divided into eight groups (n = 10/group): (i) 0.2% Chit; (ii) 0.2% NaF; (iii) 0.2% NaF/Chit suspension; (iv) 0.2% acetic acid; (v) 0.05% Chit; (vi) 0.05% NaF; (vii) 0.05% NaF/Chit suspension; and (viii) 0.05% acetic acid. Cariogenic challenge was performed in each sample by cycling in demineralization and remineralization solutions for 7 days. Before each demineralization cycle, the corresponding substances were passively applied daily for 90 s, even in groups with 0.02% concentration. After 7 days, samples were examined for Knoop hardness (KHN) measurements. The data were analyzed by repeated-measures ANOVA and Tukey tests (α = 0.05). The 0.2% NaF and 0.2% NaF/Chit groups showed higher KHNpost-challenge values than the other groups. The 0.2% NaF/Chit microparticle suspension reduced the enamel hardness loss after cariogenic challenge as effectively as the 0.2% NaF solution and demonstrated potential for use in a formulation with anti-caries effects.

Calcium phosphate ceramic as a model for enamel substitute material in dental applications

ObjectiveThis study aimed to develop enamel substitute material using a mechanochemical technique.Materials and MethodsHydroxyapatite was synthesized with and without tricalcium phosphate under uniaxial pressing of 10 and 17 MPa (HA10, HA17, BCP10, and BCP17), followed by sintering at 1250 °C for 2 h. Human enamel and dentin blocks were used as control groups. The mechanical properties were determined by compressive strength test and Vickers microhardness. The data were analyzed with one-way ANOVA and LSD post-hoc test (α = 0.05). The phase formation and morphology of the specimens were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).ResultsHA17 and HA10 had compressive strength values comparable to enamel and dentin, respectively (p > 0.05). The microhardness of all synthesized groups was significantly higher than that of tooth structures (p < 0.05). From the XRD graphs, only the hydroxyapatite peak was observed in the control and HA groups. SEM images showed homogeneous hydroxyapatite grains in all groups, while the BCP groups contained higher porosities.ConclusionsBoth HA10 and HA17 are suitable for use as the inorganic part of dentin and enamel substitutes.

Effect of Liquorice Candies on Remineralization of Initial Enamel Carious Lesion.

Glycyrrhiza glabra (G. glabra), known as liquorice root is one such herbal remedy that has been shown to have immense potential in the treatment of orofacial diseases. To evaluate the remineralizing potential of liquorice extract on initial enamel carious lesions. An in vitro and in vivo study was conducted, wherein the sound-extracted human premolars were sectioned longitudinally and into enamel blocks of size 4 × 4 mm. Enamel blocks were demineralized to produce artificial carious lesions. In vitro study, the demineralized enamel block was exposed to artificial saliva for 5 minutes and artificial saliva containing liquorice for 4 minutes 14 times in a sequential manner. An in vivo study was carried out on six volunteers aged between 6 and 12 years. The demineralized enamel block was inserted into the 5 × 5 mm window created on the full palatal coverage appliance. Patients were given commercially available liquorice candies (Ricola) to consume for 7 days twice daily. The remineralization potential of liquorice on demineralized enamel block was assessed using confocal microscopy analysis. Liquorice extract containing candies showed visual remineralization of the demineralized area on the enamel surface through confocal images. Liquorice extract possesses remineralizing potential with its other medicinal properties. . Pooja HR, Nagar P, Mascarenhas AN, et al. Effect of Liquorice Candies on Remineralization of Initial Enamel Carious Lesion. Int J Clin Pediatr Dent 2023;16(S-1):S33-S38.

Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study.

With the paradigm shift in the management of dental caries, the focus is now laid on remineralization therapies that can arrest the progression of the disease and remineralize the subsurface lesions. The purpose of this study was to determine and compare the remineralizing potential of silver diamine fluoride (SDF), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and fluoride varnish (FV) on enamel surfaces in primary and permanent teeth. A total of 120 primary anterior teeth and 120 premolars were used to prepare enamel blocks in acrylic resin. The mean baseline surface microhardness (SMH) for each sample was determined using a microvickers hardness testing machine. Thereafter, the samples were randomly and equally distributed into groups and subgroups based on the materials used, that is, SDF, CPP-ACP, FV, and distilled water (control). After subjecting the samples to a pH cycling regime, SMH was determined again and the percentage change in SMH was calculated. The data were tabulated and subjected to statistical analysis using an independent t-test and one-way analysis of variance (ANOVA). In primary teeth, the least mean percentage reduction in SMH was observed after the application of FV followed by SDF, CPP-ACP, and control. In permanent teeth, both SDF and FV showed the least percentage reduction of enamel SMH followed by CPP-ACP and control. Silver diamine fluoride (SDF), FV, and CPP-ACP showed remineralizing potential in both primary and permanent teeth. Kaur S, Bhola M, Bajaj N, et al. Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S91-S96.

Effects of Different Toothpastes on the Nanomechanical Properties and Chemical Composition of Resin-Modified Glass Ionomer Cement and Composite Resin Restorations.

This study evaluates the effects of different toothpastes on the nanohardness and chemical compositions of restorative materials and dental surfaces. Bovine enamel (n = 72) and dentin (n = 72) blocks were obtained and restored using RMGIC (n = 36) or CR (n = 36) to create the following surfaces: dentin adjacent to RMGIC (DRMGIC), enamel adjacent to RMGIC (ERMGIC), dentin adjacent to CR (DCR), and enamel adjacent to CR (ECR). After restoration, one hemiface of each specimen was coated with an acid-resistant varnish to facilitate the creation of control (C) and eroded (E) sides; the latter were achieved by erosion-abrasion cycles as follows: erosion with 1% citric acid: 5 days, four times for 2 min each day; 1% citric acid/abrasion, two times for 15 s, followed by immersion in a toothpaste slurry for 2 min. Toothpastes without fluoride (WF; n = 12), with sodium fluoride (NaF; n = 12), and with stannous fluoride (SnF2; n = 12) were used for RMGIC or CR. The specimens were analyzed for nanohardness (H), and chemical composition using energy-dispersive X-ray spectroscopy and Raman microscopy. The data were statistically analyzed using two-way repeated measures ANOVA and Tukey's test (α = 0.05). Lower H values were obtained with NaF for DRMGIC-C, with a statistically significant difference from the H value obtained with WF (p < 0.05). The calcium and phosphorus concentrations in DCR-E were significantly lower with WF than with the other types of toothpaste (p < 0.05). Fluoride-containing toothpastes are capable of preserving the main chemical components of the dentin adjacent to the restorative materials under erosive-abrasive conditions.

Effects of experimental bleaching gels containing co-doped titanium dioxide and niobium pentoxide combined with violet light.

The objective of the study is to evaluate the bleaching potential of 6% hydrogen peroxide (6% HP) gels containing NF_TiO2 or Nb2O5 irradiated with a violet LED light and the effects on enamel mineral content and surface morphology. Particles were synthesized, and experimental gels were chemically analyzed by preliminary and accelerated stability tests, pH, and HP decomposition rate. Bovine enamel blocks were treated with 6% HP gels containing (n = 10): 5% NF_TiO2, 5% Nb2O5, 2.5% NF_TiO2 + 2.5% Nb2O5 or without particles (6% HP), irradiated or not with LED, and the control was treated with 35% HP. Color (∆E00) and whitening index (∆WID) variations, surface microhardness (SH), average roughness (∆Ra), Ca-P concentration (EDS), and enamel morphology (SEM) were assessed. Bleaching was performed in 3 sessions of 30min and 7-day intervals. Data were submitted to two- (pH, decomposition rate, ∆E00, and ∆WID) or three-way ANOVA and Bonferroni (SH), Kruskal-Wallis (∆Ra), and Dunnettests (α = 0.05). No changes in the gel's color, odor, or translucency were observed. ThepH (6 to 6.5) remained stable over time, and light irradiation boosted the HP decomposition rate. NF_TiO2 and Nb2O5-containing gels displayed higher ∆E00 and ΔWID when light-irradiated (p < 0.05). Nb2O5 and Nb2O5 + NF_TiO2 decreased enamel SH (p < 0.05), but no SH changes were found among groups (p > 0.05). No differences among groups were noted in ∆Ra, Ca-P content, and enamel morphology after treatments (p > 0.05). Experimental light-irradiated 6% HP gels containing NF_TiO2 or Nb2O5 were chemically stable and exhibited bleaching potential comparable with 35% HP. Low-concentrated HP gelscontaining NF_TiO2 or Nb2O5 and light-irradiatedstand as a possible alternative to in-office bleaching.

Erosion-inhibiting and enamel rehardening effects of different types of saliva

ObjectivesThe objective of this study was to assess the effects of in situ saliva compared to in vitro human saliva, with or without mucin, on inhibiting erosion and promoting enamel rehardening. DesignBovine enamel blocks were randomly distributed into groups (n = 23): Gsitu (human saliva in situ), Gvitro (collected human saliva) and GvitroM (collected human saliva with mucin). The enamel blocks underwent a 2-hour period for the formation of salivary pellicle, based on the assigned groups. Subsequently, they were subjected to three erosive cycles, each of them consisting of an erosive challenge (immersion in 0.65 % citric acid, pH 3.5, 1 min) and saliva exposure (immersion in situ or in vitro saliva for 2 h). Microhardness measurements were performed at each cycle, after each experimental step (erosive challenge and exposure to saliva). ResultsAfter the first demineralization, in vitro saliva groups presented greater hardness loss, with no statistical difference between GVitroM and GVitro. After the third erosive demineralization the in situ saliva resulted in less hardness loss compared to the first demineralization. In relation to surface hardness recovery, there was no difference among types of saliva but there was a decrease in hardness as the cycles progressed. ConclusionSaliva groups had different behaviors between the first and third demineralization, being similar after the third cycle in terms of hardness loss. Regarding hardness recovery, all saliva promoted enamel gain, but there was a gradual decrease with the progression of the cycles.

Amyloid hexapeptide prevent dental caries by antibiofilm formation

ObjectivesBiofilm formed by cariogenic microbes is the direct cause of dental caries, therefore, prevention of dental caries should be anti-biofilm-based. Previously, we found the amyloid hexapeptides efficiently inhibited biofilm formation by aggregating into amyloid fibrils agglutinating microbes. This study aimed to select the most stable amyloid hexapeptide GIDLKI (GI6) and study its anti-caries effect. MethodsBiofilms of multi-species bacteria, derived from mixed saliva, were cultured to evaluate the anti-biofilm formation effect of GI6. And then, the primary cariogenic bacterium Streptococcus mutans (S.mutans) was cultured in BHI with various pH, gradient concentrations of sucrose, glucose, and calcium ions to evaluate the anti-biofilm formation effects of GI6. Then models of human enamel block caries and twenty male SPF-SD rat caries induced by S. mutans biofilm were constructed, and confocal laser scanning microscopy, scanning electron microscopy, and micro-computed tomography were applied to investigate the anti-biofilm formation, anti-caries effects and use safety of GI6. ResultsGI6 could inhibit the multi-species bacteria biofilm formation and remained effective in anti-biofilm activity against S. mutans in environments closely related to caries. GI6 suppressed S. mutans biofilm formation and thus prevented or alleviated the development of caries in human tooth blocks and rat teeth. GI6 did not affect the intestinal flora, serum biochemical parameters, and the pathological changes of various organs. ConclusionsAmyloid hexapeptides, including but not limited to GI6, are novel effective anti-caries agents that can be used to prevent dental caries safely. Clinical significanceThis study explored the anti-biofilm formation and anti-caries effect of GI6 in vitro, highlighting the anti-biofilm formation therapy for dental caries and setting a foundation for the practical application of GI6 for the treatment of dental caries.

Effect of Different Remineralization Agents on Artificial Caries Lesion: An in-vitro Study

Objective: Remineralization technologies have been shown to arrest or reverse early carious lesions. This study aimed to evaluate and compare the effect of different agents on enamel remineralization in-vitro. Methods: Thirty-five enamel blocks were prepared and divided into the following groups: Group 1; CaGp and Xylitol-containing gel (R.O.C.S Medical Mineral Gel), Group 2; 1100 ppm NaF and 10% CPP-ACP toothpaste (MI Paste One), Group 3; 0.45% SnF2-1150 ppm F toothpaste (Enamelon), Group 4; Positive Control-1450 ppm NaF toothpaste (Colgate Total) and Group 5; Negative Control (deionized water). Microhardness was measured at baseline, after demineralization, and after respective treatments for different treatment groups using a digital Micro Vickers Hardness Tester. For producing demineralized lesions, samples were stored in acidic hydroxyethylcellulose (HEC, pH=4.8) for three days. The Paired Sample t-test, one-way ANOVA, and Tukey were used to compare data and SMH recovery (%SMHR) calculated among treatments. Results: The mean baseline surface microhardness value was statistically non-significant between the groups (p=.378). CaGP and Xylitolcontaining gel demonstrated having the most protective effect against demineralization. The surface remineralization potential of 1100 ppm NaF and 10% CPP-ACP containing novel toothpaste (MI Paste One) was almost similar to the positive control (1450 ppm Fluoride toothpaste)group (p&gt;.05). Conclusions: All treatment groups showed remineralization after respective treatments and these agents can be used as an effective preventive measure for pediatric patients.

Regenerative and Protective Effects on Dental Tissues of a Fluoride-Silicon-Rich Toothpaste Associated with a Calcium Booster: An In Vitro Study.

Calcium boosters have been used as a supplement for fluoride toothpastes to repair the dental tissues and reduce dentin permeability. This in vitro study aimed to characterize the regenerative and protective effects of the treatment of dental tissues with a fluoride-silicon-rich toothpaste associated with a calcium booster. Bovine enamel and dentin blocks (n = 5) were obtained (4 × 4 × 6 mm). A fluoride-silicon-rich toothpaste and a calcium booster were used to brush the enamel and dentin both immediately and five days afterwards. The outcomes were then compared to those of the untreated control group. After that, the specimens were cross-sectioned. SEM was used to evaluate the micromorphology of the surface and cross-section. Energy-dispersive X-ray spectroscopy (EDS) was used to determine the elemental analyses (weight%). After treatment for 5 days with a booster/silicon-rich toothpaste, EDS analysis demonstrated that it induced a significant mineral change. It was also able to form a protective silicon-enriched mineral layer on both enamel and dentin surfaces. It was demonstrated in vitro that a fluoride-silicon-rich toothpaste associated with a calcium booster regenerates the dental tissues, remineralizing the enamel structure and occluding the dentin tubules.

Quantitative analysis of remineralization of artificial carious lesions with commercially available toothpastes using EDAX: An in vitro study

Introduction: Noninvasive approach for treating demineralized teeth is gaining importance in preventive dentistry. Various fluoridated and nonfluoridated remineralizing agents are utilized for treating early enamel carious lesions. Aim: To quantitatively assess the remineralizing potential of various dentifrices quantitatively from the array of products available in the market. Materials and Methods: Enamel blocks were prepared from seventy sound permanent teeth. The baseline amount of calcium, phosphorous, and fluoride was evaluated. After those samples were transferred in Modified TenCate’s solution for demineralization for 96 h, the amount of demineralization carried out to detect change in mineral content. Following this, samples were randomly grouped into five – Group 1: Fluoridated sensitive toothpaste, Group 2: Fluoridated toothpaste with Anticay Technology, Group 3: Nonfluoridated natural extracts toothpaste, Group 4: Nonfluoridated ayurvedic toothpaste, and Group 5: De-ionized water. Remineralizing agents applied twice daily for 28 days. The final mineral content of remineralized enamel was evaluated. Intra-group and inter-group comparisons were statistically analyzed using independent and paired sample t-test and analysis of variance. Results and Discussion: The mean calcium, phosphorous, fluoride, and Ca/P ratio of fluoridated and nonfluoridated toothpastes showed statistically significant difference (significant at P &lt; 0.05). Intergroup comparison shows fluoridated toothpaste showing greater potential for remineralization (significant at P &lt; 0.05). Conclusion: Fluoridated toothpaste with anticay technology showed better remineralizing capacity followed by sensitive and nonfluoridated natural toothpaste. Nonfluoridated ayurvedic toothpaste showed the least remineralizing potential.

Ozone gas therapy for tooth bleaching preserves enamel microhardness, roughness and surface micromor.

Bovine enamel blocks were planed and distributed among the following three bleaching treatment groups (n=10): CP - 1 hour per day/14 days (Opalescence PF 10%/ Ultradent); O - 1 hour per day every 3 days/3 sessions (Medplus V Philozon, 60 mcg/mL and oxygen flow rate of 1 L/min); and OCP - CP with O, 1 hour per day every 3 days/3 sessions. Enamel surface microhardness (Knoop), roughness (Ra), and micromorphology by scanning electron microscopy (5,000x magnification) were determined before and after the treatments. ANOVA and Tukey-Kramer’s test showed that enamel microhardness remained unchanged by treatment with O and OCP (p=0.0087), but decreased by treatment with CP. Treatment with O promoted higher enamel microhardness than the other groups (p=0.0169). Generalized linear mixed models for repeated measures over time indicated treatment with CP increased enamel roughness more than OCP or O (p=0.0003). CP produced slight irregularities in enamel micromorphology after the whitening treatment. O, with or without CP, maintained the mechanical and physical properties of microhardness and enamel surface micromorphology, and either maintained or reduced surface roughness, compared to the conventional tray-delivered CP bleaching treatment. Treatment with 10% carbamide peroxide in trays promoted greater changes in enamel surface properties than treatments with ozone and with 10% ozonized carbamide peroxide in the office.

In Vitro Evaluation of the Different Supragingival Prophylaxis Tips on Enamel Surfaces

Objective: Periodontal instrumentation during supragingival prophylaxis may increase enamel surface roughness, which may lead to increased dental biofilm accumulation and demineralization of the enamel. The aim of this study was to evaluate the changes of the enamel surface profilometrically after the application of different scaler tips used for the professional supragingival prophylaxis. Materials and methods: Forty-eight enamel block samples obtained from extracted human maxillary premolar teeth were prepared and randomly assigned to four different treatment groups. Each treatment group was instrumented by the same clinician with different tools as Group 1: Er:YAG laser chisel tip, Group 2: scaler, Group 3: new generation universal curette; and Group 4: ultrasonic device. Sample surfaces were evaluated with a profilometer before and after instrumentations and after the polishing process. Results: Baseline roughness of the prepared enamel samples was similar between the groups. After instrumentation and polishing, the Er:YAG laser chisel tip revealed the most irregular surface morphology, whereas the new generation curette induced the smoothest surface. Conclusions: New generation universal curette is a promising tool, which can be used safely for supragingival calculus removal without the need for polishing on enamel surfaces.

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.

The anti-cariogenic effect of fluoride iontophoresis on sound enamel under different working conditions: an in vitro study

Objective. This study investigated the anti-cariogenic effect of fluoride iontophoresis on sound human enamel under different working conditions. Methods. One hundred and five enamel blocks were prepared and randomly assigned to seven different groups: Fluoride iontophoresis under different working conditions, including: different electric current intensities (0.2, 0.4, 0.6 mA) and durations of current application (3, 6, 9 min); No fluoride treatment (negative control); Fluoride immersion without iontophoresis (positive control). After 7 days of pH-cycling, morphology changes on enamel surfaces were examined by scanning electron microscopy (SEM), and Vickers surface microhardness (VH) values of enamel blocks before and after treatments were assessed using a Vickers microhardness tester. KOH-soluble fluoride (KOH-F) uptakes were measured by a fluoride ion-selective electrode. Results. Distinctly roughened enamel surfaces were showed in all treatment groups, with the greatest extent damaged surface in negative control group and the least in all the fluoride intophoresis groups. All the fluoride iontophoresis groups (except for the group under 0.2 mA) showed smaller reduction of VH values (p < 0.05) and greater KOH-F (p < 0.05) when compared with the negative and positive control groups. There was an increasing trend in the loss of VH and in fluoride uptakes with an increasing current intensity. Meanwhile, the reduction of VH values and KOH-F in Group I3 ( 0.6 mA) were significantly greater (p < 0.05) than those in Group I1 ( 0.2 mA). No significant differences of reduction of VH and KOH-F presented among the three groups applied with fluoride iontophoresis under different current durations. Conclusions. Fluoride iontophoresis resulted in a significantly increased KOH-F and a reduced loss of VH after the 7 days pH-cycling procedure, and its effectiveness was influenced by different electric current intensities but not influenced by different current durations.

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.

Effects of bovine milk osteopontin on in vitro enamel remineralization as a topical application prior to immersion in remineralizing solutions with/without fluoride.

The aim of the present study was to investigate the effects of bovine milk osteopontin (OPN) on enamel remineralization as a topical application prior to immersion in remineralizing solutions with/without fluoride. Bovine enamel blocks were demineralized then were divided into the following 3 groups: OPN (2.7 and 5.4 µM) solutions and deionized water (control). Each group was divided into 2 groups (remineralizing solution with or without 1 ppm of fluoride (F)). The specimens were analyzed by micro-CT and scanning electron microscope (SEM). The percentage of remineralization was higher in remineralization solution with than without F (p<0.05). The present results suggest that bovine milk OPN inhibits remineralization in solution without F, but 5.4 µM bovine milk OPN does not inhibit remineralization of the demineralized body using solution containing F by interrupting mineral deposition on the enamel surface.

Enamel and Dentin Etching with Glycolic, Ferulic, and Phosphoric Acids: Demineralization Pattern, Surface Microhardness, and Bond Strength Stability.

This study evaluated the etching pattern, surface microhardness, and bond strength for enamel and dentin submitted to treatment with phosphoric, glycolic, and ferulic acids. Enamel and dentin blocks were treated with phosphoric, glycolic, and ferulic acid to evaluate the surface and adhesive interface by scanning electron microscopy (2000×). Surface microhardness (Knoop) was evaluated before and after etching, and microtensile bond strength was evaluated after application of a two-step adhesive system (Adper Single Bond 2, 3M ESPE) at 24 hours and 12 months storage time points. Analysis of variance (ANOVA) and Tukey's test showed a decrease in the microhardness values for both substrates after application of each acid (p<0.0001). The reduction percentage was significantly higher for enamel treated with phosphoric acid (59.9%) and glycolic acid (65.1%) than for ferulic acid (16.5%) (p<0.0001), and higher for dentin that received phosphoric acid (38.3%) versus glycolic acid (27.8%) and ferulic acid (21.9%) (p<0.0001). Phosphoric and glycolic acids led to homogeneous enamel demineralization, and promoted the opening of dentinal tubules, whereas ferulic acid led to enamel surface demineralization and partially removed the smear layer. The adhesive-enamel interface showed micromechanical embedding of the adhesive in the interprismatic spaces when phosphoric and glycolic acids were applied. Ferulic acid showed no tag formation. Microtensile bond strength at both time points, and for both substrates, was lower with ferulic acid (p=0.0003/E; p=0.0011/D; Kruskal Wallis and Dunn). The bond strength for enamel and dentin decreased when using phosphoric and glycolic acids at the 12-month time evaluation (p<0.05). Glycolic acid showed an etching pattern and microhardness similar to that of phosphoric acid. Ferulic acid was not effective in etching the enamel or dentin, and it did not provide satisfactory bond strength to dental substrates.