REMINERALIZING POTENTIAL OF CALCIUM SUCROSE PHOSPHATE IN WHITE SPOT LESIONS: A SYSTEMATIC REVIEW.

BACKGROUND: This systematic review aimed to evaluate the remineralizing efficacy of calcium sucrose phosphate (CaSP) for the treatment of white spot lesions (WSLs) that commonly occur after orthodontic treatment with fixed appliances using various randomized controlled trials (RCTs) available in the literature to date. HIGHLIGHTS: Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guidelines, RCTs that assessed the efficacious remineralizing potential of CaSP on WSLs and demineralized enamel and compared it with either no intervention or other remineralizing agents were selected. The methodological rigor of the included studies was subjected to the Risk of Bias tool-2 (ROB-2) and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tools. Furthermore, a Begg's Funnel Plot was used to assess publication bias. The qualitative analysis encompassed a corpus of 36 studies. The remineralization potential of CaSP was investigated using an array of parameters, including surface microhardness, surface morphology, surface roughness, mineral content, and lesion size and depth. Based on the ROB-2 tool, most of the included studies were judged to be high risk, largely attributable to the presence of attrition bias. Using the GRADE framework, the certainty of evidence was determined to be moderate. CONCLUSION: This systematic review reveals that CaSP yields favorable outcomes in terms of increased surface microhardness and calcium-phosphate content, reduced demineralized area and surface roughness, and enhanced surface topography.

Clinical and ex-vivo effect of LASERs on prevention of early-enamel caries: systematic review & meta-analyses.

To investigate the in vivo and in situ effect of different types of lasers in prevention of enamel demineralization in high caries risk cases (around orthodontic brackets, around restoration and in caries susceptible pits and fissures). PubMed was searched using the following keyword sequence; (Laser therapy OR laser irradiation OR laser application) AND (enamel caries prevention OR enamel demineralization OR enamel remineralization OR early enamel caries OR early-enamel caries OR enamel resistance OR enamel decalcification OR white spot lesions WSLs OR incipient lesion OR enamel decay OR enamel Dissolution OR enamel microhardness) AND (clinical trial OR Randomized clinical trial OR In situ study). The latest literature search was ended by "30 January 2023". PubMed was used as a primary data base for study selection. Scopus, EBSCO, and Google scholar are checked in our study after results of systematic search on PubMed. Only duplicates were found. Two meta-analyses were carried out. The first, clinical meta-analysis on incidence of white spot lesions (WSLs) following CO2 laser irradiation of enamel. The second meta-analysis on ex-vivo/in situ effect of CO2 laser on microhardness of enamel. In each meta-analysis three studies were included. Risk of bias was assessed. The search identified eight studies (four ex-vivo and four clinical trials). Regarding the clinical meta-analysis, the overall standardized mean difference was 0.21 [ 95% confidence interval (CI): 0.15-0.30, p < 0.00001]. This indicates that the incidence of new WSLs in patients who received low power CO2 laser treatment was highly significantly lower than placebo groups. The heterogeneity was considerable (I2 = 71%). In the second meta-analysis, the overall standardized mean difference was 49.55 [ 95% confidence interval (CI): 37.74, 61.37, p < 0.00001]. This indicates that microhardness of enamel receiving low power (0.4-5 W) CO2 laser irradiation is highly significantly lower than control untreated enamel. The heterogeneity was substantial (I2 = 48%). Within the limitations of this study, Low level laser therapy concept with CO2 laser seems to be effective in preventing enamel caries.Prospero registration number: CRD42023437379.

A Comprehensive Narrative Review of Nanomaterial Applications in Restorative Dentistry: Demineralization Inhibition and Remineralization Applications (Part I).

Nanotechnology is extensively employed in various aspects of dentistry, including restorative dentistry, because of its substantial improvement and promising potential in the clinical efficacy of restorative materials and procedures. The main purpose of this review is to explore the different uses of nanomaterials in restorative dentistry. The review is divided into two parts: the current review (Part 1) focuses on the prevention of demineralization and promotion of remineralization, while the upcoming review (Part 2) will discuss the reinforcement of restorative materials and their therapeutic applications. Nanofillers are added to dental materials to boost their antibacterial, anticaries, and demineralization inhibitory capabilities. Additionally, they improve remineralization and enhance both mechanical properties and therapeutic features. The nanoparticles (NPs) used to increase antibacterial and remineralization inhibitions can be classified into two main groups: inorganic and organic NPs. Examples of inorganic NPs include silver, zinc oxide, titanium oxide, and gold. Examples of organic NPs include silica, quaternary ammonium salt monomers, and chitosan NPs. Furthermore, the nanofillers utilized to enhance the process of remineralization include various types such as metals, nano-hydroxyapatite, nano-amorphous calcium phosphate (ACP), dicalcium phosphate NPs, casein phosphopeptide-ACP (CPP-ACP), and calcium fluoride NPs. These uses underscore the potential applications of NPs in restorative dentistry, although there are still some limitations to address.

Examining the Efficacy of 38% Silver Diamine Fluoride in Halting Active Dental Caries Lesions Among Children: A Descriptive Study.

BACKGROUND/OBJECTIVES: Dental caries, a prevalent issue among children, often leads to discomfort and potential complications. Utilizing caries-arresting treatments to slow down its progression offers a practical alternative. Previous research indicates that topical fluorides can deactivate and remineralize enamel caries. This study aims to evaluate the efficacy of 38% silver diamine fluoride (SDF) in halting active dental caries lesions in children. MATERIALS AND METHODS: This descriptive case series was conducted at the Operative Dentistry Department of the Nishtar Institute of Dentistry in Multan, Pakistan. We enrolled 753 patients aged three to nine years, of both genders, each with at least one cavitated lesion graded 3-6 according to the International Caries Detection and Assessment System (ICDAS). SDF was directly applied to dried and isolated teeth using a micro brush and left to absorb for up to two minutes (adjusted based on the child's cooperation), and parents were instructed to ensure the child refrained from eating or drinking for an hour post-application. Baseline examinations were performed by consultant restorative dentists, and reexaminations were conducted after two to three weeks by a consultant unaware of the study. RESULTS: The study included children aged three to nine years, with a mean age of 6.02±1.35 years. The majority of patients (61.75%) were aged between three and six years. Among the 753 patients, 619 (82.20%) were male, and 134 (17.80%) were female, with a male-to-female ratio of 4.6:1. The efficacy of 38% SDF in arresting active dental caries lesions in children was observed in 720 (95.62%) patients. CONCLUSION: This study demonstrates that 38% SDF is highly effective in halting active dental caries lesions in children.

Remineralization potential of apacider mangosteen adhesive pastes on artificial carious lesions.

Background/purpose: Attention to caries administration has altered toward an early finding of lesions and targeted to noninvasive management with a remineralizing agent. This study compared the remineralization potential of apacider mangosteen adhesive pastes (AMAP), 500-ppm fluoride toothpaste (FT500), and 1000-ppm fluoride toothpaste (FT1000) on artificial caries. Materials and methods: Artificial caries were generated to enamel of eighty extracted human premolars. The specimens were allocated to four groups and subjected to pH-cycling with the application of testing agents (2 min each, for 10 days): (1) AMAP, dairy, (2) FT500, twice a day, (3) FT1000, twice a day, and (4) no treatment (NT). The surface microhardness was determined before demineralization, after demineralization, and after application of pH-cycling. The hardness, percent of hardness recovery (%HR), and percent of remineralization potential (%RP) were analyzed with ANOVA and Bonferroni's test (α = 0.05). Polarized light microscopy (PLM) was assessed for lesion depth. Results: Significant differences in remineralization were observed upon various agents compared to NT (P < 0.05). A significant difference in remineralization was found among AMAP, FT1000, and FT500 (P < 0.05). No significant difference in %HR and %RP was observed between AMAP and FT1000 (P > 0.05). PLM signified greater decrease in depth for AMAP, compared to FT1000 and FT500, but no depth reduction for NT. Conclusion: AMAP possesses comparable remineralization ability to FT1000. However, decreasing in depth of carious lesions was evinced with using AMAP more than FT1000 and FT500. AMAP was recommended as a potential remineralization material for handling initial caries.

Remineralization and inactivation of carious lesions treated with silver fluoride in Brazilian children with special healthcare needs.

Introduction: Providing conventional, restorative dental care to children with special healthcare needs (CSHCN) often requires sedation using general anesthesia. Saliva consistency, diet, and oral hygiene practice are different for CSHCN, and limited evidence is available on the efficacy of silver fluoride (SF) for the management of carious lesions for this vulnerable population. Methods: Parents of CSHCN were educated about silver fluoride as a treatment option for caries. In total, 550 carious lesions from 100 participants were identified and scored according to the Nyvad Caries criteria. A total of 100 lesions with Nyvad scores 1, 2, and 3 were treated with a single application of silver fluoride and observed postoperatively at 1, 3, and 6 weeks. Result: The results indicate statistically significant (p < 0.05) differences in lesion remineralization over the 6-week follow-up period. At the 6-week follow-up, more than 85% of all lesions were remineralized across all children, regardless of condition or original Nyvad score of 1, 2, or 3. Conclusion: A single application of silver fluoride has demonstrated effectiveness in remineralization and inactivation of carious lesions over 6 weeks among Brazilian CSHCN. Silver fluoride should be considered an option for the management of carious lesions among CSHCN. Further studies are recommended, including larger sample sizes, longer follow-up times, a second application of SF, and different special needs conditions.

Enamel changes of bleached teeth following application of an experimental combination of chitosan-bioactive glass.

BACKGROUND: Considering the extensive use of bleaching agents and the occurrence of side effects such as enamel demineralization, this study aimed to assess the enamel changes of bleached teeth following the experimental application of chitosan-bioactive glass (CH-BG). METHODS: In this in vitro study, CH-BG (containing 66% BG) was synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thirty sound human premolars were bleached with 40% hydrogen peroxide, and the weight% of calcium and phosphorus elements of the buccal enamel surface was quantified before and after bleaching by scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM, EDX). Depending on the surface treatment of the enamel surface, the specimens were divided into three groups (n = 10): control (no treatment), MI Paste (MI), and CH-BG. Then the specimens were stored in artificial saliva for 14 days. The SEM/EDX analyses were performed again on the enamel surface. Data were analyzed by one-way ANOVA and Tukey's test and a p-value of < 0.05 was considered statistically significant. RESULTS: In all groups, the weight% of calcium and phosphorus elements of enamel decreased after bleaching; this reduction was significant for phosphorus (p < 0.05) and insignificant for calcium (p > 0.05). After 14 days of remineralization, the weight% of both calcium and phosphorus elements was significantly higher compared to their bleached counterparts in both MI and CH-BG groups (p < 0.05). Following the remineralization process, the difference between MI and CH-BG groups was not significant (p > 0.05) but both had a significant difference with the control group in this regard (p < 0.05). CONCLUSIONS: The synthesized CH-BG compound showed an efficacy comparable to that of MI Paste for enamel remineralization of bleached teeth.

Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study.

The study aimed to compare various toothpastes and mouthwashes on permanent tooth dentin after erosive and abrasive challenges. 130 sound premolars dentin were randomly submitted to an initial erosive challenge and a cycle of erosive and abrasive challenges for five days. The five experimental groups (n = 26) were: (1) Control group (artificial saliva), (2) Elmex erosion protection toothpaste and mouthwash, (3) Vitis anticaries biorepair toothpaste and mouthwash, (4) Oral B Pro-expert toothpaste and Oral B Fluorinse mouthwash, and (5) MI Paste ONE toothpaste and Caphosol mouthwash. Microhardness, surface roughness values, and the topographical characteristics of the dentin surface were assessed. The highest percentage of recovered dentin microhardness (%RDMH) value was observed in groups 2 and 4, followed by groups 5 and 3, respectively. The %RDMH values in groups 2 and 4 did not demonstrate a significant difference (p = 0.855). The highest percentage of improvement in surface roughness was recorded in groups 2 and 4, with no significant differences (p = 0.989). The atomic force microscopy (AFM) findings were consistent with the surface roughness data. The best recovery of dentin microhardness and roughness were measured with the Elmex and Oral B toothpaste and mouthwash, followed by MI Paste ONE toothpaste and Caphosol mouthwash and Vitis anticaries biorepair toothpaste and mouthwash.

Remineralizing effect of the association of nano-hydroxyapatite and fluoride in the treatment of initial lesions of the enamel: A systematic review.

OBJECTIVE: Assessed the effect of dental products containing nano-hydroxyapatite (nano-HA) + fluoride on the remineralization of white spot lesions (WSL) in vivo or in situ. METHODS: Seven databases were explored using a two-pronged approach (intervention/treatment). After screening, full-text assessment, and further exclusion, the qualitative synthesis of five studies (four clinical and one in situ) was performed. Based on the Cochrane collaboration guidelines relevant data of the studies were collected and summarized. The Cochrane risk of bias tool for randomized trials (RoB 2.0) was used to appraise the studies' methodological quality and the GRADE guidelines to assess their level of evidence. The RoB 2.0 domains were rated on their risk of bias (RoB) as low, high, or with some concerns, and an adaptation of the tool was used to the in situ study. RESULTS: The included studies assessed 151 WSL in anterior permanent teeth, on patients with varying ages. The protocol application, treatment length (7d-12 w), and control groups varied greatly between the studies making the performance of a quantitative analysis unfeasible. The general RoB of the clinical studies was classified as being of low risk (n = 2) or some concerns (n = 2). The in situ study was considered as being of low risk. The level of the evidence was moderate. Most of the studies found moderate evidence regarding the superiority of this association in clinical settings. CONCLUSION: Even with the nano-HA + fluoride promising results for the remineralization treatment of WSL, due to the restricted number of studies and types of products, its extended use cannot be recommended based on the current systematic review, especially when considering the moderate level of the evidence found. CLINICAL SIGNIFICANCE: Due to the biocompatibility and higher surface coverage of nano-HA and the remineralization capacity of fluoride formulations, the association of these elements to remineralize WSL has been positively reported. After the collection and qualitative appraise of the data, the clinical evidence of the use of these dental products is promising but limited.

Fluoride-amorphous calcium phosphate and biomimetic nano-hydroxyapatite for enamel remineralization: An in-vitro study of surface microhardness and composition.

AIM: Fluoride-Amorphous Calcium Phosphate and Biomimetic Nano-Hydroxyapatite for Enamel Remineralization; An In-Vitro Study of Surface Microhardness and Composition. MATERIAL AND METHODS: Ninety-six extracted human premolars with sound buccal surface were divided using a randomization computer-generating software into four groups; Group I (control) sound untreated enamel, Group II (demineralized) demineralized to create white spot lesions, Group III (biom-n-HA) demineralized and then treated with biomimetic nanohydroxyapatite cream, and Group IV (F-ACP) demineralized and then treated using Fluoride-Amorphous Calcium Phosphate varnish. Each group was divided into two subgroups; subgroup "A" evaluated for mineral content using energy dispersive x-ray spectroscopy (EDX) and for surface microhardness using the Vickers microhardness test and Subgroup "B" evaluated for white spot lesion depth using a polarized light microscope (PLM). RESULTS: The highest microhardness (VHN) was found in the (F-ACP) group (mean=428.61±54.43) and then in the (Biom-n-HA) group (mean=408.11±70.16) followed by the (Control) group (mean=402.13±53.40) with no significant difference between them and finally in the significantly different (Demineralized) group (mean=256.99±45.83). The weight percentage of Ca (30.29±1.04 and 33.44±1.07) and Ca/P ratio (1.87±0.06 and 2.03±0.05) were significantly different between Group III and Group IV respectively. PLM measurements in Group II (198.83µm), Group III (60.17µm), and Group IV (26.33µm) were significantly different. CONCLUSIONS: Both the (Biom-n-HA) cream and the (F-ACP) varnish showed promising results for enamel remineralization. The increased enamel surface microhardness was consistent with the mineral content and the changes in the birefringence.

Characterization of chemical reactions of silver diammine fluoride and hydroxyapatite under remineralization conditions.

Introduction: Silver Diammine Fluoride (SDF) is a clinically used topical agent to arrest dental caries. However, the kinetics of its chemical interactions with hydroxyapatite (HA), the principal inorganic component of dental enamel, are not known. The aim was to characterize the step-wise chemical interactions between SDF and HA powder during the clinically important process of remineralization. Methods: Two grams of HA powder were immersed in 10 ml acetic acid pH = 4.0 for 2 h to mimic carious demineralization. The powder was then washed and dried for 24 h and mixed with 1.5 ml SDF (Riva Star) for 1 min. The treated powder was then air-dried for 3 min, and 0.2 g was removed and stored in individual tubes each containing 10 ml remineralizing solution. Powder was taken from each tube at various times of exposure to remineralization solution (0 min, 10 min, 2 h, 4 h, 8 h, 24 h, and 10 days), and characterized using Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR) spectroscopy. Results and discussion: 19F MAS-NMR spectra showed that calcium fluoride (CaF2) started to form almost immediately after HA was in contact with SDF. After 24 h, the peak shifted to -104.5 ppm suggesting that fluoride substituted hydroxyapatite (FSHA) was formed with time at the expense of CaF2. The 31P MAS-NMR spectra showed a single peak at 2.7 ppm at all time points showing that the only phosphate species present was crystalline apatite. The 35Cl MAS-NMR spectra showed formation of silver chloride (AgCl) at 24 h. It was observed that after the scan, the whitish HA powder changed to black color. In conclusion, this time sequence study showed that under remineralization conditions, SDF initially reacted with HA to form CaF2 which is then transformed to FSHA over time. In the presence of chloride, AgCl is formed which is subsequently photo-reduced to black metallic silver.

Biomineralization and remineralizing potential of toothpastes containing nanosized ß-calcium glycerophosphate: an in vitro study.

To evaluate the effect of 1100 ppm F toothpastes supplemented with micrometric or nanosized ß-CaGP (ß-CaGPm/ß-CaGPn) on artificial enamel remineralization, using a pH cycling model. Enamel blocks with artificial caries were randomly allocated into ten groups (n = 10), according to the toothpastes: without fluoride/ß-CaGPm/ß-CaGPn (negative control); 1100 ppm F (1100F); 1100F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. The blocks were treated 2×/day with slurries of toothpastes. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); integrated mineral loss (ΔIMR); fluoride (F), calcium (Ca), and phosphorus (P) concentrations in the enamel; polydispersity index (PdI); and zeta potential (Zp) were determined. The data were analyzed by ANOVA (p < 0.001). For Zp/PdI, no significance was observed when comparing the means (p > 0.001). The treatment with 1100F-0.25%ß-CaGPn led to %SHR ∼57 higher when compared to the 1100F group (p < 0.001). The lowest ΔKHN was observed for the 1100F-0.25%ß-CaGPn group (p < 0.001). The ΔIMR was lower (∼201%) for the 1100F-0.25%ß-CaGPn when compared to 1100F (p < 0.001). The association of ß-CaGPm and ß-CaGPn to 1100F did not influence its F concentration (p > 0.001). The highest increase in Ca and P was observed for 1100F-0.25%ß-CaGPn (p < 0.001). The addition of 0.25%ß-CaGPn to 1100F toothpaste was able to promote an additional remineralizing effect of artificial caries lesions.

Effect of strontium fluoride on mechanical and remineralization properties of enamel: An in-vitro study on a modified orthodontic adhesive.

OBJECTIVES: Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. METHODS: Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF2, 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. RESULTS: FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO43- and ν1 CO32- along with carbonate - / ν1PO43- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. SIGNIFICANCE: Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel.

Natural, biphasic calcium phosphate from fish bones for enamel remineralization and dentin tubules occlusion.

OBJECTIVES: A calcium phosphate extracted from fish bones (CaP-N) was evaluated for enamel remineralization and dentinal tubules occlusion. METHODS: CaP-N was characterized by assessing morphology by SEM, crystallinity by PXRD, and composition by ICP-OES. CaP-N morphology, crystallinity, ion release, and pH changes over time in neutral and acidic solutions were studied. CaP-N was then tested to assess remineralization and dentinal tubules occlusion on demineralized human enamel and dentin specimens (n = 6). Synthetic calcium phosphate in form of stoichiometric hydroxyapatite nanoparticles (CaP-S) and tap water were positive and negative controls, respectively. After treatment (brush every 12 h for 5d and storage in Dulbecco's modified PBS), specimens' morphology and surface composition were assessed (by SEM-EDS), while the viscoelastic behavior was evaluated with microindentation and DMA. RESULTS: CaP-N consisted of rounded microparticles (200 nm - 1 µm) composed of 33 wt% hydroxyapatite and 67 wt% ß-tricalcium phosphate. In acidic solution, CaP-N released calcium and phosphate ions thanks to the preferential ß-tricalcium phosphate phase dissolution. Enamel remineralization was induced by CaP-N comparably to CaP-S, while CaP-N exhibited a superior dentinal tubule occlusion than CaP-S, forming mineral plugs and depositing new nanoparticles onto demineralized collagen. This behavior was attributed to its bigger particle size and increased solubility. DMA depth profiling and SEM showed an excellent interaction between the newly formed mineralized structures and the pristine tissue, particularly at the exposed collagen fibrils. SIGNIFICANCE: CaP-N demonstrated very good remineralizing and occlusive activity in vitro, comparable to CaP-S, thus could be a promising circular economy alternative therapeutic agent for dentistry.

Nanotechnology in toothpaste: Fundamentals, trends, and safety.

Several studies have revealed that healthcare nanomaterials are widely used in numerous areas of dentistry, including prevention, diagnosis, treatment, and repair. Nanomaterials in dental cosmetics are utilized to enhance the efficacy of toothpaste and other mouthwashes. Nanoparticles are added to toothpastes for a variety of reasons, including dental decay prevention, remineralization, hypersensitivity reduction, brightening, and antibacterial qualities. In this review, the benefits and uses of many common nanomaterials found in toothpaste are outlined. Additionally, the capacity and clinical applications of nanoparticles as anti-bacterial, whitening, hypersensitivity, and remineralizing agents in the treatment of dental problems and periodontitis are discussed.

Comparative evaluation of remineralization potential of four different remineralization agents on human enamel: An in vitro study.

Aim: The study aimed to assess the remineralizing potential of four different commercially available agents using a Scanning Electron Microscope (SEM), energy dispersive X-ray (EDX) analysis, and Vickers Microhardness (VMH) Test. Materials and Methods: Forty-four specimens (n = 11 per group) were prepared from extracted teeth. A window of 6 mm × 4 mm was made on all the specimens that represented three zones, namely, sound enamel, demineralized enamel, and remineralized enamel. The zone for demineralized enamel was subjected to four different remineralizing agents; casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF), tricalcium phosphate fluoride (TCP-F), calcium sucrose phosphate (CSP), and self-assembling peptide (P11-4). Remineralization (REM) was assessed using VMH; the structural changes were assessed using SEM that was analyzed using EDX analysis. The specimens were subjected to a newer regimen of demineralization. One-way ANOVA followed by post hoc Tukey test was used with a level of significance at P ≤ 0.05. Results: There were no significant differences in VMH between the groups for sound enamel (P = 0.472) and demineralized enamel (P = 0.116). VMH was statistically significantly more for P11-4 and the least for CPP-ACPF (P = 0.011). A post hoc analysis revealed higher VMH for P11-4 compared to CPP-ACPF (P = 0.014) and TCP-F (P = 0.035). SEM showed a homogeneous layer of minerals for all groups except CPP-ACPF. TCP-F reported a higher degree of REM, followed by P11-4 as assessed using EDX analysis. Conclusion: Self-assembling peptide (P11-4) exhibited a higher degree of REM than other remineralizing agents followed by CSP.

Dissolved silica affects the bulk iron redox state and recrystallization of minerals generated by photoferrotrophy in a simulated Archean ocean.

Chemical sedimentary deposits called Banded Iron Formations (BIFs) are one of the best surviving records of ancient marine (bio)geochemistry. Many BIF precursor sediments precipitated from ferruginous, silica-rich waters prior to the Great Oxidation Event at ~2.43 Ga. Reconstructing the mineralogy of BIF precursor phases is key to understanding the coevolution of seawater chemistry and early life. Many models of BIF deposition invoke the activity of Fe(II)-oxidizing photoautotrophic bacteria as a mechanism for precipitating mixed-valence Fe(II,III) and/or fully oxidized Fe(III) minerals in the absence of molecular oxygen. Although the identity of phases produced by ancient photoferrotrophs remains debated, laboratory experiments provide a means to explore what their mineral byproducts might have been. Few studies have thoroughly characterized precipitates produced by photoferrotrophs in settings representative of Archean oceans, including investigating how residual Fe(II)aq can affect the mineralogy of expected solid phases. The concentration of dissolved silica (Si) is also an important variable to consider, as silicate species may influence the identity and reactivity of Fe(III)-bearing phases. To address these uncertainties, we cultured Rhodopseudomonas palustris TIE-1 as a photoferrotroph in synthetic Archean seawater with an initial [Fe(II)aq ] of 1 mM and [Si] spanning 0-1.5 mM. Ferrihydrite was the dominant precipitate across all Si concentrations, even with substantial Fe(II) remaining in solution. Consistent with other studies of microbial iron oxidation, no Fe-silicates were observed across the silica gradient, although Si coprecipitated with ferrihydrite via surface adsorption. More crystalline phases such as lepidocrocite and goethite were only detected at low [Si] and are likely products of Fe(II)-catalyzed ferrihydrite transformation. Finally, we observed a substantial fraction of Fe(II) in precipitates, with the proportion of Fe(II) increasing as a function of [Si]. These experimental results suggest that photoferrotrophy in a Fe(II)-buffered ocean may have exported Fe(II,III)-oxide/silica admixtures to BIF sediments, providing a more chemically diverse substrate than previously hypothesized.

Preferential remineralization of phosphorus from organic matter in river-dominated coastal sediments.

In coastal sediments characterized by substantial terrestrial input, the Redfield ratio may not be adequate to determine whether phosphorus (P) is preferentially remineralized relative to carbon (C). Employing a two end-member δ13C mixing model, we observed a gradual decrease in the fraction of terrestrial organic matter as the distance from the river mouth increased. Consequently, the C/P ratio of sedimentary organic matter before early diagenetic alteration (Cu/Pu) decreased from 213 ± 26 to 126 ± 4. In contrast, the C/P ratio of sedimentary organic matter after early diagenetic alteration (Corg/Porg) increased from 208 ± 32 to 265 ± 23. The deviation of Corg/Porg ratios from Cu/Pu ratios suggests that P was preferentially remineralized from organic matter relative to C. Moreover, the degree of preferential remineralization (DPR) of P, represented by (Corg/Porg)/(Cu/Pu), increased with the distance from the river mouth, suggesting a connection to cross-shelf transport. Besides preferential P remineralization, the control mechanisms for P regeneration from sediments strongly depend on the dissolved oxygen (DO) levels of bottom water. Under oxygenated bottom water (DO >120 µM), the precipitation of Fe oxides reduced benthic DIP flux, resulting in a C/P ratio in flux well above the Cu/Pu ratio (1813 ± 725 vs. 213 ± 26). Conversely, when bottom water DO was low (DO<100 µM), the dissolution of Fe oxides and preferential P remineralization increased DIP fluxes, but the precipitation of authigenic apatite suppressed DIP fluxes, leading to C/P ratios in flux approximating Cu/Pu ratios (129 ± 35 vs. 158 ± 10 and 200 ± 82 vs. 141 ± 7). In a moderate redox state (100 < DO <120 µM), preferential P remineralization and the dissolution of Fe oxides increased DIP fluxes, resulting in C/P ratios in flux below Cu/Pu ratios (29 ± 8 vs. 131 ± 5 and 15 ± 6 vs. 126 ± 4).

Investigating the efficacy of a varnish containing gallic acid on remineralization of enamel lesions: an in vitro study.

This study evaluated the efficacy of a formulated remineralizing gallic acid (GA) varnish in treating artificial enamel caries lesions. Fifty-five intact bovine incisors were collected. Enamel blocks (5 × 9 mm) were prepared. A third of each block's surface remained intact. Primary carious lesions were induced on the middle and bottom thirds of the blocks by immersing the samples in a demineralization solution for 6 h. The bottom third of the blocks were further remineralized by randomly applying 0.5%, 2%, or 8% GA varnishes and 2.26% fluoride varnish (V varnish, Vericom, Seoul, Korea), or the varnish base without active ingredients (n = 11 each). The specimens were immersed in a remineralizing solution for 4 h and then subjected to a 2-hour immersion in the demineralizing solution. After six days of pH cycling, the surface microhardness was measured at depths of 30, 75, and 120 µm. The percentage of surface microhardness recovery (SMHR%) was compared among the groups using the Shapiro-Wilk, ANOVA, and Tukey HSD post-hoc tests (α = 0.05). The SMHR% of all experimental groups was higher than the control group at 30 µm (p < 0.05). The 0.5% GA varnish showed the highest SMHR% at all depths; however, the difference with the other experimental groups was significant at a depth of 30 µm (p < 0.05). The SMHR% of the fluoride and the 2% and 8% GA varnishes was comparable at all depths. All treatments potentially remineralize enamel lesions, with 0.5% GA varnish having the greatest effect, particularly on the top surface layer. As such, this newly developed varnish may emerge as a promising alternative to fluoride varnish.

Urchin-like multiscale structured fluorinated hydroxyapatite as versatile filler for caries restoration dental resin composites.

Caries is one of the most prevalent human diseases, resulting from demineralization of tooth hard tissue caused by acids produced from bacteria, and can progress to pulpal inflammation. Filling restoration with dental resin composites (DRCs) is currently the most common treatment for caries. However, existing DRCs suffer from low fracture strength and lack comprehensive anti-caries bioactivity including remineralization, pulp protection, and anti-cariogenic bacteria effects. In this study, inspired by plant roots' ability to stabilize and improve soil, fluorinated urchin-like hydroxyapatite (FUHA) with a three-dimensional whisker structure and bioactive components of calcium, phosphorus, and fluorine was designed and synthesized by a dynamic self-assembly method. Furthermore, versatile FUHA particles with different loading fractions were used as functional fillers to fabricate methacrylate-based DRCs, where the urchin-like hydroxyapatite (UHA) filled DRCs and commercial DRCs (Z350XT and BEAUTIFIL II) served as the control groups. The results demonstrated that FUHA with 50 wt% loading in resin matrix endowed DRC (F5) with excellent physicochemical properties, dentin remineralization property, cell viability, promotion of dental pulp stem cells mineralization, and antibacterial properties. Meanwhile, F5 also presented good clinical handling and aesthetic characteristics. Therefore, structure/functional-integrated FUHA filled DRCs have potential as a promising strategy for tooth restoration and anti-caries bioactivity.