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Objectives: To evaluate the erosion preventive effect of 38 % silver diamine fluoride (SDF) solution in enamel and dentin of human permanent teeth., Methods: Ninety enamel and ninety dentin blocks were prepared from permanent molars and allocated into three groups. Gp-SDF received a one-off application of 38 % SDF solution. Gp-SNF received a one-off application of a solution containing 800 ppm stannous chloride and 500 ppm fluoride. Gp-DW received a one-off application of deionized water. The blocks were submitted to acid challenge at pH 3.2, 2 min, 5 times/day for 7 days. All blocks were immersed in human saliva between cycles for one hour. The crystal characteristics, percentage of surface microhardness loss (%SMHL), surface loss, and elemental analysis and surface morphology were examined by X-ray diffraction (XRD), microhardness test, non-contact profilometry, and energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM), respectively. Data of%SMHL and surface loss were analyzed by one-way ANOVA., Results: XRD spectra revealed that fluorapatite and silver compounds formed in Gp-SDF, while fluorapatite and stannous compounds formed in Gp-SNF. Gp-DW presented only hydroxyapatite. The median (interquartile range) of%SMHL in Gp-SDF, Gp-SNF and Gp-DW were 27.86(3.66), 43.41(2.45), and 46.40(3.54) in enamel (p< 0.001), and 14.21(1.57), 27.99(1.95), and 33.18(1.73) in dentin, respectively (p < 0.001). The mean (standard deviation, μm) of surface loss of Gp-SDF, Gp-SNF, and Gp-DW were 2.81(0.59), 4.28(0.67), and 4.63(0.64) in enamel (p < 0.001) and 4.13(0.69), 6.04(0.61), and 7.72(0.66) in dentin, respectively (p < 0.001). SEM images exhibited less enamel corruption and more dentinal tubular occlusion in Gp-SDF compared to Gp-SNF and Gp-DW. EDS analysis showed silver was detected in Gp-SDF while stannous was detected in the dentin block of Gp-SNF., Conclusion: 38 % SDF yielded superior results in protecting enamel and dentin blocks from dental erosion compared to SNF and DW., Clinical Significance: Topical application of 38 % SDF is effective in preventing dental erosion in human enamel and dentin., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: This in vitro study investigated the ability of a blue protein-based hydroxyapatite porosity probe to selectively detect artificial enamel caries-like lesions of varying severities., Methods: Artificial caries-like lesions were formed in enamel specimens using a hydroxyethylcellulose-containing lactic acid gel for 4/12/24/72 or 168 h. One untreated group was used as a control. The probe was applied for 2 min and unbound probe rinsed off with deionized water. Surface color changes were determined spectrophotometrically (L*a*b* color space) and with digital photography. Lesions were characterized using quantitative light-induced fluorescence (QLF), Vickers surface microhardness, and transverse microradiography (TMR). Data were analyzed using one-way ANOVA., Results: Digital photography did not reveal any discoloration in unaffected enamel. However, all lesions stained blue with color intensity positively correlated with demineralization times. The color data reflected similar trends: lesions became significantly darker (L* decreased) and bluer (b* decreased), while overall color differences (ΔE) increased significantly after probe application (4-h lesion, mean±standard deviation: ΔL*=-2.6 ± 4.1/Δb*=0.1 ± 0.8/ΔE=5.5 ± 1.3 vs. 168-h lesion: ΔL*=-17.3 ± 1.1/Δb*=-6.0 ± 0.6/ΔE=18.7 ± 1.1). TMR analysis revealed distinct differences in integrated mineral loss (ΔZ) and lesion depth (L) between demineralization times (4-h lesion: ΔZ=391±190 vol%min × µm/L = 18.1 ± 10.9 µm vs. 168-h lesion: ΔZ=3606±499 vol%min × µm/L = 111.9 ± 13.9 µm). QLF and microhardness were also able to differentiate between demineralization times. L and ΔZ strongly correlated (Pearson correlation coefficient [r]) with Δb* (L vs. Δb*: r=-0.90/ΔZ vs. Δb*: r=-0.90), ΔE (r = 0.85/r = 0.81), and ΔL* (r=-0.79/r=-0.73)., Conclusion: Considering the limitations of this study, the blue protein-based hydroxyapatite-binding porosity probe appears to be sufficiently sensitive to distinguish between unaffected enamel and artificial caries-like lesions., Clinical Significance: Early detection of enamel caries lesions remains one of the most critical aspects in the diagnosis and management of dental caries. This study highlighted the potential of a novel porosity probe in detecting artificial caries-like demineralization by objective means., Competing Interests: Declaration of Competing Interest This work was support by Incisive Technologies Pty Ltd, Melbourne, Victoria, Australia. JEM and KAH are employees of and have equity in Incisive Technologies., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objective: This study investigated the possibility of using ethylenediaminetetraacetic acid functionalized silica nanoparticles (EDTA-SiO 2 ) as a dentin-conditioning agent using etch-and-rinse technique to promote the durability of dentin bonding., Methods: The SiO 2 -EDTA were synthesized by N- [(3- trimethoxysilyl) propyl] ethylenediamine triacetic acid (EDTA-TMS) and SiO 2 (50 nm), then characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The capacity of SiO 2 -EDTA to chelate calcium ions from dentin was examined by inductively coupled plasma-optic emission spectrometry (ICP-OES). The dentin surfaces conditioned with SiO 2 -EDTA were detected by field emission scanning electron microscopy (SEM), TEM and microhardness testing. For dentin bonding, dentin surfaces were adopted wet- or dry-bonding technique and bonded with adhesive (Adper TM Single Bond2) and applied composite resin (Filtek Z350) on them. The durability of dentin bonding was evaluated by mircotensile bond strength test, in-situ zymography and nanoleakage testing., Results: FTIR, TGA and XPS results showed that SiO 2 -EDTA contained N element and carboxyl groups. SEM, TEM and microhardness results indicated that SiO 2 -EDTA group created extrafibrillar demineralization and retained more intrafibrillar minerals within dentin surface. In the dentin bonding experiment, SiO 2 -EDTA group achieved acceptable bond strength, and reduced the activity of matrix metalloproteinase and nanoleakage along bonding interface., Conclusion: It was possible to generate a feasible dentin conditioning agent (SiO 2 -EDTA), which could create dentin extrafibrillar demineralization and improve dentin bond durability., Clinical Significance: This study introduces a new dentin conditioning scheme based on SiO 2 -EDTA to create extrafibrillar demineralization for dentin bonding. This strategy has the potential to be used in clinic to promote the life of restoration bonding., Competing Interests: Declaration of Competing Interest The authors report no declarations of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: This study evaluated the caries wall lesion development in different composite-dentin interfaces to investigate if the presence and location of two bonding materials in the gaps influence wall caries lesion development. Methods: Fourteen volunteers wore a modified occlusal splint containing samples with four different interfaces: perfect bonding/no gap, or with a fixed gap (234 ± 30 μm) with either no bonding material, bonding material (Clearfil Protect Bond-PB and Clearfil SE Bond-SE) on dentin or on composite. Eight times a day, the samples were dipped in 20% sucrose solution for 10 min, during 3 weeks. The samples were imaged with microradiography (T-WIM), and lesion depth (LD) and mineral loss (ML) were measured. The data were analysed with paired t-test. Results: The perfect bonding group did not show any caries wall lesion development, whereas all other interfaces did. The interface with bonding on dentin did not show significantly different wall lesion development from the interface with no material. However, when bonding was present on composite, both LD and ML were significantly higher than both other gap conditions (p-values < 0.05). A difference between the bonding material was only seen when applied on composite: PB showed less ML than SE (p = 0.01). Conclusions: The presence of bonding on the composite side of a composite-dentin gap increased wall lesion development in situ. Clinical significance: The presence and location of an adhesive bonding material in the composite-dentin gaps plays a role on the wall caries lesion development. [ABSTRACT FROM AUTHOR]

Objectives: The present in vitro pH cycling study investigated potential differences between caries lesions created in fluorosed and sound enamel with regards to their responsiveness to fluoride under remineralizing conditions. Methods: 360 human first molars (sound and fluorosed) were divided into four groups based on their Thylstrup-Fejerskov score (TF0-3). Each group was further divided into two treatment groups (n = 45): deionized water or 383 ppm fluoride. Artificial enamel caries lesions were created and pH cycled for 20 d using an established net remineralization model. Quantitative light-induced fluorescence was used throughout the study to investigate lesion severity and changes thereof. Data were analyzed using two-way ANOVA. Results: There were no differences in lesion severity between all groups after lesion creation (plesion = 0.1934). The TF score vs. treatment interaction was significant at all other time points (p10 d = 0.0280; p20 d ≤ 0.0001; psecdemin = 0.0411). Relative differences in responsiveness to fluoride vs. deionized water increased with increasing TF scores. In comparison to lesions created in sound enamel, lesions created in enamel with moderate fluorosis (TF 2/3) were more prone to remineralization in the presence than in the absence of fluoride. Furthermore, lesions created in enamel with moderate fluorosis exhibited more remineralization in the presence of fluoride than lesions created in sound teeth, whereas the opposite was true for deionized water. Conclusion: Bearing in mind the limitations of laboratory research, the extent of enamel fluorosis severity may directly impact subsequent lesion re- and progression as well as the lesion's responsiveness to fluoride. Clinical relevance: Caries lesions in fluorotic teeth are more vulnerable to progression but respond more strongly to fluoride than those in non-impacted teeth. [ABSTRACT FROM AUTHOR]

Objectives: A priority research area in minimal intervention dentistry is the characterization of the early stages of dental erosion. The aim of this in vitro study was to assess the effect of short, repetitive erosive challenges to human enamel over 2 min at pH 1.5 and 3.0 under conditions simulating gastric regurgitation. Methods: Enamel surfaces were subjected to erosive challenges at pH 1.5 (Group 1, n = 10) and pH 3.0 (Group 2, n = 9) for periods of 30 s (stage 1), 60 s (stage 2) and 120 s (stage 3). Quantitative changes were assessed longitudinally by measuring the 3D average surface roughness (Sa) values using 3D confocal microscopy. Qualitative micrographic assessment of surface changes was also conducted by using environmental scanning electron microscopy. Results: Linear mixed model analysis showed significant effects of the pH values ( p < 0.001) and the stages (p < 0.001) on the observed Sa values. Post hoc tests showed significant increases in the Sa values between baseline and other stages in both groups (p < 0.01). The mean Sa values also increased significantly from stage 1 to stage 2 in Group 1 (p < 0.05). Micrographic analysis displayed severely etched enamel rods in Group 1, but only subtle changes in Group 2. Conclusions: The complexity of the enamel surface is influenced by both acid concentration (pH value) and duration of acid exposure during early stages of erosion. Erosion occurring under conditions simulating GORD can be detected in its initial stages, opening up the possibilities of early diagnosis and management of this condition. Clinical significance: Erosive tooth wear occurs progressively and insidiously, often creating complex treatment challenges. This emphasizes the need for early diagnosis and management in accordance with minimal intervention philosophy. Our findings provide a foundation for further research that could lead to the development of highlysensitive clinical diagnostic tools and preventive strategies. [ABSTRACT FROM AUTHOR]

Objectives: This randomised in situ study aimed to analyse the effect of milk (with or without 5 ppm F) and CPP-ACP pastes (with or without 900 ppm F) on dental erosion. Methods: The study was a seven phase (5 days each) crossover design involving 15 participants wearing intraoral appliances with enamel and dentine specimens. Specimens were extraorally eroded (erosive soft drink, 6 x 90 s/day) and brushed (2 x 30 s/day, 2 N) using a non-fluoridated toothpaste (negative control). The test products were milk, milk + 5 ppm F (twice daily, each 100 ml/2 min), CPP-ACP paste, CPP-ACP paste + 900 ppm F (3 min/day) or a SnCl2/AmF/NaF mouthrinse (positive control, 30 s/day), which were applied immediately after erosion with the appliances in the oral cavity. In an additional group, a fluoridated toothpaste was used without any additional test product. Tissue loss was determined profilometrically after 5 days and statistically analysed by linear mixed models methodologies (p < 0.05). Results: Compared with the negative control (non-fluoridated toothpaste only, enamel: 2.2 ± 1.3 μm; dentine: 3.8 ± 2.2 μm), enamel and dentine loss was significantly reduced by the use of fluoridated toothpaste (enamel: 1.1 ± 1.0 μm; dentine: 2.4 ± 1.7 μm) and the SnCl2/AmF/NaF mouthrinse (1.5 ± 1.5 μm; dentine: 1.8 ± 1.9 μm). Conclusions: Milk and CPP-ACP were not effective in reducing enamel and dentine loss significantly, independently of the presence of fluoride. Clinical significance: Enamel and dentine erosion were significantly reduced by the use of a fluoridated toothpaste or a SnCl2/AmF/NaF mouthrinse, but not by milk or CPP-ACP under the conditions of the present study. Clinical trials registration: NCT01566357 [ABSTRACT FROM AUTHOR]

Objectives: Zinc salts are formulated into oral health products as antibacterial agents, yet their interaction with enamel is not clearly understood. The aim was to investigate the effect of zinc concentration [Zn2+] on the in vitro demineralization of enamel during exposure to caries-simulating conditions. Furthermore, the possible mechanism of zinc's action for reducing demineralization was determined. Methods: Enamel blocks and synthetic hydroxyapatite (HAp) were demineralized in a range of zinc-containing acidic solutions (0-3565 ppm [Zn2+]) at pH 4.0 and 37 °C. Inductively coupled-plasma optical emission spectroscopy (ICP-OES) was used to measure ion release into solution. Enamel blocks were analysed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and HAp by X-ray diffraction (XRD) and neutron diffraction (ND). Results: ICP-OES analysis of the acidic solutions showed a decrease in [Ca2+] and [PO43-] release with increasing [Zn2+]. FTIR revealed a α-hopeite (α-Zn3(PO4)2.4H2O)-like phase on the enamel surfaces at >107 ppm [Zn2+]. XRD and ND analysis confirmed a zinc-phosphate phase present alongside the HAp. Conclusions: This study confirms that zinc reduces enamel demineralization. Under the conditions studied, zinc acts predominantly on enamel surfaces at PO43- sites in the HAp lattice to possibly form an α-hopeite-like phase. Clinical significance: These results have a significant implication on the understanding of the fundamental chemistry of zinc in toothpastes and demonstrate its therapeutic potential in preventing tooth mineral loss. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present study was to measure the effects of fluoride concentration on the real-time in vitro demineralization of enamel during exposure to caries-simulating conditions using Scanning Microradiography (SMR). Methods: Enamel blocks obtained from non-carious human molars were fixed in SMR environmental cells, through which acidic solutions (0.1 M acetic acid, pH 4.0) were circulated for periods of 48 h. SMR was used to quantitatively measure continuous mineral mass loss. Subsequently, the effects of sequentially increasing fluoride concentration (0.1- 4500 mg/L [F-]) in the acidic solutions were measured on the rate of enamel demineraliza- tion. Results: The data shows a log-linear relationship between [F-] and reduction in deminer- alization up to 135 mg/L [F-]. Above 135 mg/L, no further significant decrease in deminer- alization occurred. Conclusion: The optimum range of local fluoride concentration for reducing enamel demi- neralization was in the range 0.1-135 mg/L [F-] under the conditions studied. Clinical significance: Relatively low [F-] can exhibit near-optimum protection. Increasing the fluoride concentrations above 135 mg/L may not necessarily give an increased cariostatic benefit. Improving the means of delivery of relatively low fluoride concen- trations to the oral fluids through slow releasing mechanisms, such as the oral fluoride reservoirs, is the more appropriate way forward for sustaining long-term clinical efficacy. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the anticaries effect of low-fluoride toothpastes combined with hexametaphosphate (HMP) on enamel demineralization. Methods: Bovine enamel blocks were subjected to pH cycling and treatment with toothpaste's slurries (15 groups; 2/day). Toothpaste mixtures contained the following: no fluoride (F) plus HMP (from 0 to 3.0%); 250 ppm F plus HMP (from 0 to 3.0%); 500 ppm F; 1100 ppm F; and a commercial toothpaste (1100 ppm F). After pH cycling, surface and crosssectional hardness, as well as F present in the enamel were determined. The demineralization depth was analyzed using polarized light microscopy. The variables were subjected to 1-way ANOVA, followed by Student-Newman-Keuls' test ( p < 0.05). Results: In the absence of fluoride, 0.5% HMP promoted the lowest mineral loss and its effect was similar to that of a 250 ppm F toothpaste ( p > 0.05). The combination of 0.5% HMP and 250 ppm F resulted in lower mineral loss ( p < 0.05) and similar lesion depth when compared to the 1100 ppm F toothpaste ( p > 0.05). Conclusion: To conclude, the combination of 0.5% HMP and 250 ppm fluoride in a toothpaste has a similar inhibitory effect on enamel demineralization in vitro when compared to a toothpaste containing 1100 ppm F. Clinical significance: The anticaries effect of toothpaste containing 250 ppm F combined with 0.5% HMP was similar to that of a 1100 ppm F toothpaste, despite the 4-fold difference in F concentration. Although such effects still need to be demonstrated in clinical studies, it may be a viable alternative for preschool children. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of fluoride (F) varnishes supplemented or not with sodium trimetaphosphate (TMP) on enamel erosive wear followed or not by abrasion in situ. Methods: Ten volunteers were selected and randomly divided into four groups, according to the varnishes tested: placebo (no F or TMP), 5% NaF (positive control), 2.5% NaF and 2.5% NaF/5% TMP. Enamel blocks (n = 4) were mounted in palatal devices and received an application of each test varnish, following a double-blind, crossover protocol. After 6 h, varnishes were completely removed and the blocks were subjected to erosive challenges by ex vivo immersion in citric acid (5 min, 4×/dia, 5 days). Following, half of the blocks were subjected to abrasion by brushing with a placebo dentifrice slurry for 15 s. Enamel wear (μm), surface hardness (SHf) and cross-sectional hardness (ΔKHN) were assessed after each experimental period. Results were analyzed by ANOVA, Student-Newman-Keuls's test and Pearson correlation coefficient ( p < 0.05). Results: The fluoride varnish supplemented with TMP promoted significantly lower wear and ΔKHN when compared to the other groups after erosive challenges, followed or not by abrasion ( p < 0.05). As for (SHf) the fluoride varnish supplemented with TMP promoted similar results to the 5% NaF product, being significantly higher than the remaining groups after erosive and erosive + abrasive challenges ( p < 0.05). Conclusion: TMP significantly enhanced the effects of F on enamel wear after erosive challenges, followed or not by abrasion. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The aim of this study was to investigate the effect of Ca3SiO5 on reducing enamel demineralization under pH-cycling conditions. Methods: Forty bovine enamel samples were treated under four conditions: group 1, double distilled water (negative control); group 2, 1000ppm F (as NaF, positive control); group 3, Ca3SiO5 slurry; and group 4, Ca3SiO5–F slurry (Ca3SiO5 with 1000ppm F aq.). All the specimens were treated with treatment materials 4 times each day. Samples in groups 1 and 2 were soaked in test solutions for 2min and samples in groups 3 and 4 were painted in treatment slurry for 2min. At times between treatments, they were immersed in citric acid solution 3 times a day and 15s each time. All the procedures were repeated for 7 days. Knoop microhardness, scanning electron microscopy (SEM), X-ray diffraction (XRD) and atom force microscopy (AFM) were used to examine samples. Results: After treatment for 7 days, enamels in all the groups were significantly softened. The extents of microhardness reduction were 52.3%, 28.5%, 28.5% and 20.2% for groups 1, 2, 3 and 4, respectively. Samples in the negative control group showed a typical acid etched pattern while enamels in other groups were relatively compact. There was no significant difference between samples treated with Ca3SiO5 and F. The combination of Ca3SiO5 with F showed the best effect on reducing enamel demineralization. Conclusions: Ca3SiO5 is an effective material against enamel demineralization alone but in combination with F a better anti-demineralization effect may be obtained. [Copyright &y& Elsevier]

Abstract: Objectives: The purpose of this study was to consider the impact of surface defects on quantitative light-induced fluorescence (QLF) and micro-digital-photography (MDP) measures, in relationship to lesion depth. Methods: Simulated enamel carious lesions were developed on 45 extracted human teeth. Images of each tooth were captured with both QLF and MDP. The teeth were sectioned and lesion depth was measured with polarized light microscopy (PLM). Pearson correlations were computed using data from the 27 lesions which did not have surface loss, and then separately based upon the 18 lesions which did display surface loss. MDP variables ΔR and ΔX measure reflected light, whereas QLF variables ΔF and ΔQ measure fluorescence. Results: A strong correlation was identified between lesion depth and ΔF (r =−0.765, p <0.0001), and ΔQ (r =−0.827, p <0.0001) on intact lesions while a weak but suggestive, although non-significant, correlation was identified between average lesion depth and ΔR (r =0.369, p =0.059) and ΔX (r =0.595, p =0.0011). However, the corresponding correlation was not statistically significant, when lesions with surface loss were considered for QLF and MDP measures. Conclusions: QLF measures ΔF and ΔQ were strongly correlated with lesion depth in lab-simulated lesions with no surface loss, but not among lesions with surface defects. The two MDP-associated measures, ΔR and ΔX, could not be said to differ significantly when lesions with and without surface defects were compared with lesion depth. Because intact lesions can be remineralized, accurate assessment of their status is imperative for caries treatment. Clinical significance: Dental caries is still widely prevalent today. We now know that with early stage detection, remineralization can be accomplished. Being able to identify dental caries in its reversible stage (before physical surface loss) is paramount for the clinician to be able to treat the disease non-invasively. [Copyright &y& Elsevier]

Abstract: Objectives: To investigate the potential of an active attachment biofilm model as a high-throughput demineralization biofilm model for the evaluation of caries-preventive agents. Methods: Streptococcus mutans UA159 biofilms were grown on bovine dentine discs in a high-throughput active attachment model. Biofilms were first formed in a medium with high buffer capacity for 24h and then subjected to various photodynamic therapies (PACT) using the combination of Light Emitting Diodes (LEDs, Biotable®) and Photogem®. Viability of the biofilms was evaluated by plate counts. To investigate treatment effects on dentine lesion formation, the treated biofilms were grown in a medium with low buffer capacity for an additional 24h. Integrated mineral loss (IML) and lesion depth (LD) were assessed by transversal microradiography. Calcium release in the biofilm medium was measured by atomic absorption spectroscopy. Results: Compared to the water treated control group, significant reduction in viability of S. mutans biofilms was observed when the combination of LEDs and Photogem® was applied. LEDs or Photogem® only did not result in biofilm viability changes. Similar outcomes were also found for dentine lesion formation. Significant lower IML and LD values were only found in the group subjected to the combined treatment of LEDs and Photogem®. There was a good correlation between the calcium release data and the IML or LD values. Conclusions: The high-throughput active attachment biofilm model is applicable for evaluating novel caries-preventive agents on both biofilm and demineralization inhibition. PACT had a killing effect on 24h S. mutans biofilms and could inhibit the demineralization process. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the erosive potential of orange juice modified by food additives in enamel and dentine. Methods: Calcium lactate pentahydrate (CLP), xanthan gum (XG), sodium linear polyphosphate (LPP), sodium pyrophosphate tetrabasic (PP), sodium tripolyphosphate (STP) and some of their combinations were added to an orange juice. Pure orange juice and a calcium-modified juice were used as negative (C−) and positive (C+) controls, respectively. In phase 1, 15 modified orange juices were tested for erosive potential using pH-stat analysis. In phase 2, the additives alone and the combination with good results in phase 1 and in previous studies (CLP+LPP) were tested in an erosion–remineralization cycling model. In phase 3, the erosion and remineralization episodes were studied independently. Enamel was analysed by surface microhardness (SMH) and profilometry, whilst dentine by profilometry. Results: In phase 1, reduction of the erosive potential was observed for all additives and their combinations, except XG alone. In phase 2, no detectable enamel loss was observed when CLP, LPP and CLP+LPP were added to the juice. XG, STP and PP had enamel loss similar to C− (p >0.05). Amongst additives, the combination CLP+LPP showed the highest SMH values followed by CLP (p <0.05). All the other groups presented SMH values similar to C− (p >0.05). For dentine, only CLP+LPP lead to surface loss values lower than C− (p <0.05). In phase 3, CLP, LPP and CLP+LPP seemed to protect against erosion; whilst none of the tested compounds seemed to interfere with the remineralization process. Conclusions: CLP and LPP reduced erosion on enamel and this effect was enhanced by their combination. For dentine, only the combination CLP+LPP reduced erosion. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this in vitro study was to assess the effect of toothpastes containing three different sodium fluoride concentrations and a calcium sodium phosphosilicate system, on root dentine demineralization and remineralization. Methods: During a fourteen-day pH-cycling protocol, pre-softened bovine root dentine specimens were immersed twice daily, before and after the demineralization periods, for 2min, in the following toothpaste slurries: (a) non-fluoridated (control), (b) 7.5% calcium sodium phosphosilicate, (c) 1450ppm F, (d) 2800ppm F, and (e) 5000ppm F. Subsequently, the slabs were subjected to a fifty-hour acid resistance test. Knoop microhardness at different lesion depths was assessed in specimen cross-sections and KHN values were converted to vol.% mineral. Comparisons between the groups were performed at each lesion depth through ANOVA-based tests and furthermore, regression analysis of the derived statistic of “integrated vol.% mineral loss” was carried out. Also, lesions were evaluated qualitatively using transmission and polarized light microscopy. Results: The 5000ppm F toothpaste group, during pH-cycling, presented significantly less total vol.% mineral loss and subsequently exhibited considerably increased surface acid resistance, compared to all the other tested groups. The calcium sodium phosphosilicate toothpaste, during pH-cycling, inhibited demineralization and/or promoted remineralization of the surface layers significantly more effectively than the control group nevertheless, subsequently, the acid resistance of the calcium sodium phosphosilicate dentifrice group was similar to that of the control group. These observations were confirmed by microscopic examination of the lesions. Conclusions: Under the present experimental conditions, the 5000ppm F toothpaste, promoted remineralization and inhibited demineralization more effectively, than the other tested toothpastes. [Copyright &y& Elsevier]

Abstract: Objectives: The aims of the present study were to investigate whether irradiation with a CO2 laser could prevent surface softening (i) in sound and (ii) in already softened enamel in vitro. Methods: 130 human enamel samples were obtained and polished with silicon carbide papers. They were divided into 10 groups (n =13) receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C); and submitted to 2 different procedures: half of the groups was acid-softened before surface treatment and the other half after. Immersion in 1% citric acid was the acid challenge. Surface microhardness (SMH) was measured at baseline, after softening and after treatment. Additionally, fluoride uptake in the enamel was quantified. The data were statistically analysed by two-way repeated measurements ANOVA and post hoc comparisons at 5% significance level. Results: When softening was performed either before or after laser treatment, the L group presented at the end of the experiments SMH means that were not significantly different from baseline (p =0.8432, p =0.4620). Treatment after softening resulted for all laser groups in statistically significant increase in SMH means as compared to values after softening (p <0.0001). Enamel fluoride uptake was significantly higher for combined laser-fluoride treatment than in control (p <0.0001). Conclusion: Irradiation of dental enamel with a CO2 laser at 0.3J/cm2 (5μs, 226Hz) not only significantly decreased erosive mineral loss (97%) but also rehardened previously softened enamel in vitro. [Copyright &y& Elsevier]

Abstract: Objectives: The present study evaluated the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and CPP-ACP with 900ppm fluoride (CPP-ACPF) pastes on inhibition of enamel demineralization over time, using polychromatic micro-computed tomography (micro-CT). Methods: Enamel blocks were prepared from bovine teeth. The specimens were each treated by one of the following agents, 30min daily for 7 days: deionized water (negative control); CPP-ACP paste; CPP-ACPF paste; and NaF solutions (positive controls) (90, 900, and 9000ppm F). After treatment, the specimens were immersed in a demineralizing solution (pH 4.5) for 24, 72, and 120h. Mean mineral loss (ML) and lesion depth (LD) after each period were determined from mineral density profiles obtained using micro-CT. Results: ML values in all the treatment groups were significantly smaller than those in the control group after 72 and 120h of demineralization (p <0.05, two-way ANOVA and t-test with Bonferroni correction). ML values in CPP-ACPF and NaF solution groups were significantly smaller compared to CPP-ACP group after 72h (p <0.05). LD values in the CPP-ACPF and all the NaF solutions groups were significantly smaller compared to the control group after 120h (p <0.05). The 9000ppm F group showed the lowest nominal ML and LD values. Conclusions: The application of CPP-ACP or CPP-ACPF pastes to sound enamel surfaces resulted in inhibition of enamel demineralization, and a better effect was noted for the latter paste. Quantitative assessment using polychromatic micro-CT demonstrated to be useful for detecting mineral density changes. [Copyright &y& Elsevier]

Objectives: Dentin matrix metalloproteinases are implicated in the pathogenesis of caries and contribute to collagen degradation in resin-dentin interfaces. The objective was to determine if collagen degradation may be modulated by an excess of zinc or zinc chelators.Methods: Mineralized and phosphoric acid demineralized human dentin specimens were tested. Chlorhexidine digluconate, doxycycline or ZnCl₂ were added to the media. In half of the groups, active exogenous metalloproteinase-2 was incorporated into the solution. C-terminal telopeptide determinations (radioimmunoassay) were performed after 24 h, 1 and 3 weeks.Results: Collagen degradation was prominent in demineralized dentin. Doxycycline fully blocked dentin proteolysis. Chlorhexidine digluconate reduced the degradation at the 24-h period. Zinc in excess strongly inhibits hydrolysis of collagen and its effect was maintained for 3 weeks.Conclusions: Zinc in excess reduces MMP-mediated collagen degradation. The hypothesis that binding of zinc to collagen results in protection of sensitive cleavage sites of metalloproteinases requires further validation. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The aim of this work was to evaluate the in vitro effect of chitosan (concentration and time of action) treatment on enamel de-remineralization behavior upon a pH cycling assay. Methods: Different group of human tooth samples were exposed to de-remineralizing solutions of controlled pH using a random experimental design. Microhardness and phosphorus chemical analysis were employed to evaluate the loss of phosphorus from the samples. Optical coherence tomography (OCT) images were obtained for selected specimens in order to evaluate the degree of penetration of chitosan into enamel. Results: Vickers microhardness results were higher for samples treated with chitosan for concentration between 2.5mg/mL and 5.0mg/mL and time of action between 60s and 90s. A maximum inhibition of mineral loss of 81% was obtained. Chemical analysis indicated lower net pohosphorus loss (net P loss) for samples treated with chitosan. Best results were obtained in the same conditions found out with microhardness measurements. Chitosan had little effect on the remineralization process. OCT results indicated a correlation of chitosan penetration with chitosan concentration. For chitosan concentrations of 2.5g/mL and 5.0g/mL the penetration was up to the dentin–enamel junction. Conclusions: Chitosan interferes with the process of demineralization of the tooth enamel inhibiting the release of phosphorus in this laboratory study. Demineralization is influenced by the concentration and exposure time of the biopolymer to the enamel. Microhardness measurements may be used as an indication of mineral loss from tooth enamel. Additionally, OCT images support the idea that chitosan may act as a barrier against acid penetration, contributing to its demineralization inhibition. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The purpose of this in vitro study was to evaluate the effect of toothpastes containing sodium fluoride in different concentrations or a calcium sodium phosphosilicate system on pre-softened dentin demineralization and remineralization. Methods: During a ten day pH-cycling protocol, pre-softened bovine root dentin slabs were immersed twice daily, after the demineralization periods, for 2min, in the following toothpaste slurries: (a) non-fluoridated (control), (b) 7.5% calcium sodium phosphosilicate, (c) 1450ppm F, (d) 2800ppm F and (e) 5000ppm F. Subsequently, the specimens were subjected to a 15-h acid resistance test. Surface microhardness was assessed initially and during the pH-cycling and the acid resistance test period. Repeated measurements in each group were analyzed through appropriate regression models for longitudinal data. Results: All fluoride groups, during pH cycling, showed significantly less microhardness loss (p ≤0.010, p ≤0.002, p ≤0.002) and subsequently exhibited increased acid resistance (p ≤0.010, p ≤0.001, p ≤0.001) compared to the control. The 5000ppm and 2800ppm F toothpastes, inhibited demineralization significantly more effectively than the 1450ppm F (p ≤0.001, p ≤0.030) and the calcium sodium phosphosilicate toothpaste (p ≤0.001), while no significant differences were found between the two high fluoride groups (p =0.130). The calcium sodium phosphosilicate toothpaste, during pH cycling showed a difference that approached statistical significance compared to control (p =0.079), but its acid resistance behavior was similar to control (p =0.610). Conclusions: Under these experimental conditions, the high fluoride toothpastes promoted remineralization and inhibited demineralization more effectively, than the 1450ppm F, the non-fluoridated (control) and the calcium sodium phosphosilicate toothpastes. [Copyright &y& Elsevier]

Abstract: Objectives: To compare the demineralization pattern that occurs in abraded samples and unabraded ones quantitatively and microscopically using nanoindentation and SEM. Methods: Using 12 human third molars, one half of each tooth was abraded to a depth approximately 200μm below the outer surface enamel, and the other half was left untreated. All specimens were demineralized for 3d, 5d, 7d and 14d respectively. The cross sections of all lesions were evaluated with nanoindentation and SEM. Results: Unabraded samples had least loss of mechanical properties and lesion depth compared to abraded samples, with most mechanical property loss occurring within a shallower layer of the lesion. The variation of mechanical properties in unabraded samples was wider than abraded samples. SEM images showed a characteristic “keyhole” structure for both samples after demineralization, with the rod core extensively demineralized while the interrod remained intact. Acid attack initiated at the rod sheath space then penetrated into the rod core before extending into neighbouring rods through the rod tail. Conclusion: Abraded samples exposed to in vitro demineralization form deeper lesion depths and greater loss of mechanical properties than unabraded samples subjected to the same demineralization. Unabraded samples manifested characteristic subsurface demineralization with a shallow surface layer that remained intact, whereas no intact surface was found in abraded samples. The demineralization pattern of unabraded samples more closely resembled the pattern of natural white spot lesions and displayed wide inter-sample variation. Consideration should be given to experimental design with unabraded teeth specimens for future demineralization studies. [Copyright &y& Elsevier]

Summary: Objectives: Interproximal enamel reduction (orthodontic stripping) leaves surface-roughness that encourages plaque adherence. Sealants and fluoride products have been recommended to avoid possible detrimental effects. The objective of this study was to qualitatively evaluate, by means of scanning electron microscopy (SEM), the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on stripped enamel morphology after exposure to an acid solution. Methods: 15 extracted lower incisors underwent stripping with metal strips (Horico, 80μm) by 1 operator. Mesial and distal surfaces were sectioned into 30 samples (22 stripped; 8 unstripped) and assigned to 2 groups: Group A (2 stripped; 2 unstripped) served as control; in Group B (20 stripped; 6 unstripped) tooth mousse containing CPP-ACP was tested. For 8 days, teeth were placed in acid lactic solution for 2h three times a day (from 9a.m. to 9p.m.) with 2h water preservation in between. After each demineralizing bath, samples of group B were coated with CPP-ACP for 5min before immersion into water. Results: In Group A, stripped samples exhibited greater demineralization compared to unstripped. In Group B, CPP-ACP reduced enamel dissolution on both intact and abraded samples compared to Group A. Conclusions: Injuries to enamel morphology caused by stripping might predispose to greater demineralization in the event of exposure to acid environment. Topical applications of CPP-ACP could be effective in promoting enamel remineralization after interdental stripping. [Copyright &y& Elsevier]

Abstract: Objectives: This study evaluated possible differences regarding the remineralization of predemineralized enamel after exposure to fluoridated or non-fluoridated bleaching gels. Methods: 120 enamel specimens were prepared from sixty bovine incisors; before and after demineralization (37°C; pH 4.95; 10d), one-quarter of each specimen''s surface was covered with nail varnish (control sound/demineralized). Subsequently, the specimens were stored for 16h daily in a remineralizing solution (pH 7.0; 14d), while for the remaining time (8h) various bleaching gels were applied: (1) no treatment (control), (2) Opalescence regular (O, Ultradent), (3) Opalescence PF (O-PF), (4) Nite White ACP (NW-ACP, Discus Dental) and (5) Nite White ACPF (NW-ACPF). Following, half of the bleached parts were nail-varnished and stored for another 3-weeks period in a remineralizing solution. Differences in mineral losses (ΔΔZ) and lesion depths (ΔLD) before and after treatment/remineralization period were evaluated from microradiographs. ΔΔZ surface values (mineral loss of the outer 18μm of the lesion) were calculated. Results: After 2 and 5 weeks ΔΔZ/ΔLD values of the bleaching groups did not differ significantly from the controls. Treatment with NW-ACPF for 2 weeks resulted in significantly lower ΔΔZ values compared to NW-ACP (p =0.032) and NW-ACPF in higher values than Opalescence regular (p =0.006). Two weeks treatment with O and O-PF resulted in decreased ΔΔZ surface values compared to control (p <0.0005), whereas with NW-ACPF no significant differences could be observed (p =0.062). Application of NW-ACP induced significantly increased ΔΔZ surface values compared to control (p =0.001). Conclusions: No supporting influence of fluoride-containing bleaching gels on remineralization could be observed. [Copyright &y& Elsevier]

Abstract: Objective: The purpose of this study was to monitor in situ acid-induced demineralization of dentine by using electrochemical impedance spectroscopy (EIS) and correlate the EIS findings with changes in the chemical composition and ultrastructure of dentine. Method: EIS was used to monitor the process of demineralization of dentine induced by an acid model. Scanning electron microscopy (SEM) was used to examine the ultrastructure, while energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis were employed to investigate the changes in the chemical composition of surface dentine with demineralization. Results: Two kinds of equivalent circuits that matched the histological structure of dentine were used to fit the EIS data. The parameters R d, which is the resistance of the bulk of dentine layer and R ct, which is the charge transfer associated with the penetration of electrolyte into the dentinal tubules, decreased with increasing duration of demineralization. SEM images showed that the smear layer on the dentine and peritubular dentine disappeared with demineralization. The EDX results showed that the content of calcium and phosphorus decreased consistently with the decreasing content of HAP as shown by the XRD results. The findings from this study suggested that the changes in R d and R ct determined by the EIS corresponded well with the variation in structure and composition of dentine. Conclusions: EIS could be employed to monitor structural and chemical compositional changes induced by acid-demineralization on dentine surface. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the effects of fluoridated bleaching agents and post-bleaching fluoridation treatment on the whitening efficiency and microhardness of bovine enamel. Methods: Twenty five freshly extracted bovine incisors were cut into halves, embedded and then divided into the following five groups: Group 1, untreated controls; Group 2, treatment with 10% carbamide peroxide (CP) bleaching agent; Group 3, treatment with 10% CP followed by a 0.9% sodium fluoride gel application, Group 4, treatment with 10% CP containing 0.11% fluoride; Group 5, treatment with an experimental bleaching agent consisting of 10% CP and 0.37% fluoride. Groups 2–5 were treated 8h per day for 14 days then immersed in saliva for 2 weeks. Enamel morphology changes were evaluated under SEM on Day 14. Changes in enamel color and microhardness were evaluated on Days 7 and 14, and compared with the baseline data. Additionally, microhardness was determined on post-bleaching Days 21 and 28. Results: After 2 weeks, an erosion pattern was noted on the specimens in Groups 2 and 3. Groups 4 and 5 showed a milder demineralized pattern. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 3 showed significantly decreased enamel microhardness compared to their baseline data. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. Conclusions: The fluoridated bleaching agents produced less demineralization of surface morphology and microhardness. The addition of fluoride did not impede the whitening effect. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this study was to determine in vitro the effect of a commercial paste based on CPP-ACP complex on the demineralization of sound human dentine and on remineralization potential of artificial caries-like lesions formed on dentine surfaces. Methods: Forty dentine specimens were prepared with hard tissue microtome. The specimens were divided in four groups the A, B, C and D (n =10). The specimen surfaces were subjected to surface analysis by Fourier transformance micro multiple internal reflectance infrared spectroscopy (micro MIR-FTIR). Tooth mousse was applied on surface specimens of A group, while no agent were applied on the specimens of B group. Afterwards, groups A, B, C and D were immersed in demineralization solution for 7 days. Afterwards, the surfaces were subjected to micro MIR-FTIR analysis and the mineral to matrix ratio was used to assess the extent of dentin demineralization (DM). Tooth mousse was applied on specimens of group C, while no agent was applied on specimens of group D. The groups C and D immersed in artificial saliva for 7 days and were subjected to analysis by micro MIR-FTIR and the mineral to matrix ratio was used to assess the extent of dentin remineralization (RM). Results: Group A showed significant lower %DM in comparison to group B. Group C resulted in a significant higher %RM compared to group D. Conclusions: The presence of agent CPP-ACP on dentine surfaces provoked lower demineralization and higher remineralization in comparison with the dentine surfaces without agent. [Copyright &y& Elsevier]

Abstract: For in situ studies into caries prevention, sterilization of tooth samples is essential. However, sterilization may influence the caries process itself. The aim of this study was to assess the effect of sterilising sound human enamel and dentin with ethylene oxide on lesion depth and mineral loss before and after in vitro demineralization. Lesion depth and mineral loss were measured using transversal microradiography (TMR). The experiment was carried out with 32 enamel and 32 dentin samples. We found a significant reduction of lesion depth due to sterilization in demineralized enamel (−9.8μm; 95% CI: −15.1 to −4.4μm). The small effect of sterilization on demineralized enamel is considered to be irrelevant for in situ studies of de- and remineralization. [Copyright &y& Elsevier]

Abstract: Objectives: The efficacy of three techniques for the disinfection of artificial sub-surface root caries lesions and their response to subsequent episodes of de- and remineralization was investigated quantitatively in vitro. Methods: Sub-surface dentinal lesions (n =20), cut into four experimental blocks and deliberately contaminated with Streptococcus mutans, were subject to either steam autoclaving (121°C, 5min), gamma irradiation (4100Gy), immersion in 0.1% (w/v) thymol-distilled water solution (24h) or reserved as a control. Next, the lesions were incubated aerobically in sterile nutrient broth for 24h at 37°C and resultant cultures plated onto blood agar and neutralisation agar. Ten blocks from each experimental group were then immersed in an acidic buffer solution or exposed to artificial saliva for 5 days. Baseline changes in the mineral content and distribution of the lesions were assessed by transverse microradiography (TMR). Results: Micro-organisms were recovered from each control block and one block treated by gamma irradiation. Steam autoclaving and immersion in a thymol solution significantly decreased (p <0.05) the amount of mineral lost from the body of lesions subject to a further acid challenge. Mineral ion uptake by lesions exposed to artificial saliva was significantly increased (p <0.05) through disinfection by steam autoclaving. Conclusions: Gamma irradiation proved the most acceptable method for the disinfection of sub-surface root dentine lesions having the least adverse effect on demineralization and remineralization. [Copyright &y& Elsevier]

Abstract: Objective: The purpose of this study was to in situ characterize the demineralization (namely dissolution of hydroxyapatite) on the surface of the human enamel using electrochemical impedance spectroscopy (EIS) technology. Methods: Fresh human third molars extracted without visible evidence of caries, were used in this study. After they were immersed in a demineralizing solution prepared from lactic acid and carboxy methyl cellulose sodium (Na-CMC) buffering at pH 4, demineralization happened on their surfaces. EIS of the specimens were measured at a series of immersed interval. X-ray diffractometer (XRD) were used to distinguish the microstructure of the surface layer of the specimens. The depositions that appeared in the demineralizing solution after 46h immersion were analyzed by fourier transform infrared spectrometer (FTIR). Results: XRD analysis revealed that the percentage of intensity (I%) of HAP gradually decreased with the elapsed immersing time, which indicated the dissolution of HAP columns of enamel. Nyquist spectra were fitted with an equivalent circuit characterized by some parameters, such as Q and R p (error<0.1%). Changes of the parameters’ values revealed that the rate of demineralization accelerated at the forepart of the demineralization, but slowed down beyond 70h immersion. Conclusions: The results suggested that EIS was proved to be a useful method for in situ investigating and in vivo detecting the demineralization of the enamel. [Copyright &y& Elsevier]

Abstract: Objectives: There is increasing prevalence of root caries. We hypothesized different biofilms will cause varying demineralization in cementum. This study investigated the extent of demineralization of cementum by oral biofilm formed from three major cariogenic microorganisms: Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces israelii. Sound cementum tooth blocks were incubated with mono-, bi-, and tri-species combinations of the bacteria under investigation. Materials and methods: The matrix (amide I) and phosphate content of the lesions was analyzed by Fourier-transform infrared spectroscopy (FTIR), and calcium and phosphorus levels were analyzed by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDX). Results: The log[amide I:HPO4 2− absorbance] values showed that A. israelii mono-culture caused significantly more demineralization than the other bacterial cultures. log[Ca:P] showed that all carious lesions were confined to the cementum. Conclusions: Oral biofilm arising from bacterial species A. israelii alone was the most cariogenic of those tested and produced the most demineralization in incipient carious lesions in cementum. [Copyright &y& Elsevier]