Evaluation of toothpastes for treating root carious lesions - a laboratory-based pilot study.

BACKGROUND: Root caries is preventable and can be arrested at any stage of disease development. The aim of this study was to investigate the potential mineral exchange and fluorapatite formation within artificial root carious lesions (ARCLs) using different toothpastes containing 5,000 ppm F, 1,450 ppm F or bioactive glass (BG) with 540 ppm F. MATERIALS AND METHODS: The crowns of each extracted sound tooth were removed. The remaining roots were divided into four parts (n = 12). Each sample was randomly allocated into one of four groups: Group 1 (Deionised water); Group 2 (BG with 540 ppm F); Group 3 (1,450 ppm F) and Group 4 (5,000 ppm F). ARCLs were developed using demineralisation solution (pH 4.8). The samples were then pH-cycled in 13 days using demineralisation solution (6 h) and remineralisation solution (pH 7) (16 h). Standard tooth brushing was carried out twice a day with the assigned toothpaste. X-ray Microtomography (XMT) was performed for each sample at baseline, following ARCL formation and after 13-day pH-cycling. Scanning Electron Microscope (SEM) and 19F Magic angle spinning nuclear magnetic resonance (19F-MAS-NMR) were also performed. RESULTS: XMT results showed that the highest mineral content increase (mean ± SD) was Group 4 (0.09 ± 0.05), whilst the mineral content decreased in Group 1 (-0.08 ± 0.06) after 13-day pH-cycling, however there was evidence of mineral loss within the subsurface for Groups 1, 3 and 4 (p < 0.05). SEM scans showed that mineral contents within the surface of dentine tubules were high in comparison to the subsurface in all toothpaste groups. There was evidence of dentine tubules being either partially or completely occluded in toothpaste groups. 19F-MAS-NMR showed peaks between - 103 and - 104ppm corresponding to fluorapatite formation in Groups 3 and 4. CONCLUSION: Within the limitation of this laboratory-based study, all toothpastes were potentially effective to increase the mineral density of artificial root caries on the surface, however there was evidence of mineral loss within the subsurface for Groups 1, 3 and 4.

Intratracheal administration of polystyrene microplastics induces pulmonary fibrosis by activating oxidative stress and Wnt/ß-catenin signaling pathway in mice.

Polystyrene microplastics (PS-MPs) are emerging pollutants that are absorbed by organisms. Due to their small volume and strong biological permeability, they affect the biological functions of cells. In recent years, several studies have detected PS-MPs in air samples, which may damage the human respiratory system following inhalation. The Masson trichrome staining, immunofluorescence, and western blotting assays were conducted to analyze the effects of PS-MPs on pulmonary fibrosis. Alveolar epithelial injuries were assessed through confocal microscopy, and the levels of SOD and GSH were used to evaluate oxidative stress. Our analyzes demonstrated that inhalation of the PS-MPs induces pulmonary fibrosis in a dose-dependent manner in mice. In high dose group (6.25 mg/kg), the PS-MPs significantly increased the expression of α-SMA, Vimentin and Col1a (p < 0.05). Immunofluorescence assays showed decreased levels of SP-C and increased levels of KL-6 in the PS-MPs group. The suppression of SOD (1.46 times) and GSH-Px (2.27 times) indicated that inhalation of microplastics triggered intensive oxidative stress in lungs. Moreover, there was activation of the Wnt/ß-catenin signaling pathway in the PS-MPs group. In addition, the data showed that antioxidant melatonin (50 mg/kg) alleviated the PS-MPs-induced pulmonary fibrosis. Taken together, our analysis demonstrated that inhalation of polystyrene microplastics induces pulmonary fibrosis via activation of oxidative stress and Wnt/ß-catenin signaling pathway in mice.

The effect of different concentrations of fluoride in toothpastes with or without bioactive glass on artificial root caries.

OBJECTIVE: To investigate the effect of different toothpastes either containing 5,000ppm-F, 1,450ppm-F or bioactive glass (BG) with 540ppm-F on artificial root carious lesions (ARCLs). METHOD: The crowns of 23 extracted sound teeth were removed leaving their roots only. Subsequently, each root was divided into four parts. A total of 15 sound root dentine (SRD) was left untreated as baseline. The ARCLs were developed for the remaining roots using demineralisation solution (pH-4.8). 15-ARCLs samples were then left untreated. The rest of samples were divided into four groups (n = 15 each) and treated with Group-1(BG with 540ppm-F); Group-2(5000ppm-F); Group-3(1450ppm-F) and Group-4(deionised water). 13-day pH-cycling included using demineralisation solution for 6 h, then placing samples into remineralisation solution (pH-7) for 16 h. Each sample was brushed with the assigned toothpaste twice a day during pH-cycling. Fluoride concentrations at each time point were measured using F-ISE, whilst calcium (Ca2+) and phosphorus (P) ion release was determined using ICP-OES, KHN, XRD, 19F-MAS-NMR analyses. RESULTS: KHN showed significant surface changes for each group (p<0.001). The uptake of Ca2+ occurred at days 1-2, phosphorus ion loss was high when compared to the uptake in all groups. XRD showed presence of sharp diffraction lines evidencing apatite formation for Groups 1-3. 19F-MAS-NMR confirmed fluorapatite presence in Groups 1-3. CONCLUSION: All toothpastes were promising in fluorapatite formation. BG with 540ppm-F toothpaste released more ions (Ca2+and P) and reharden the artificial root carious lesions when compared to other groups. However, 1450ppm-F toothpaste showed more fluoride-substituted apatite formation whilst 5000ppm-F toothpaste had more fluorapatite formation. CLINICAL SIGNIFICANCE: Toothpaste containing BG with 540ppm-F, 5000ppm-F and 1450ppm-F toothpastes are likely to have a significant impact in reversing and arresting root caries. However, randomised controlled double-blinded clinical trials are required to translate these results into clinical practice.

A systematic review on the effect of silver diamine fluoride for management of dental caries in permanent teeth.

OBJECTIVES: The objective of this review is to assess the available literature systematically related to the effect of silver diamine fluoride (SDF) for the management of occlusal and root carious lesions in permanent teeth regardless of age. MATERIALS AND METHODS: This systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses statement. A literature search was performed using PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ, and Open Gray with no language restrictions up to December 2022. Three reviewers critically assessed the studies for eligibility. Any disputes between the reviewers were handled by a fourth independent reviewer. The quality assessment and data extraction of the studies were performed. RESULTS: A total of 2176 studies were screened. The titles and abstracts of the studies were then reviewed (n = 346), and 52 studies met the search criteria. Following the full-text review, 11 studies investigated the effect of SDF against other treatments such as chlorhexidine, sodium fluoride, ammonium bifluoride, tricalcium silicate paste, casein phosphopeptide amorphous calcium phosphate, glass ionomer cement (GIC) combined with fluoride varnish, resin-modified GIC, and atraumatic restorative treatment were assessed. CONCLUSIONS: Within the limitations of this review, the use of SDF is promising with high preventative fractions in permanent teeth of children and older populations when compared to other topical applications such as dental varnish containing sodium fluoride.

Amplification of oxidative damage using near-infrared II-mediated photothermal/thermocatalytic effects for periodontitis treatment.

Periodontitis is a biofilm-related disease characterized by damage to the periodontal tissue and the development of systemic diseases. However, treatment of periodontitis remains unsatisfactory, especially with deep-tissue infections. This study describes rationally designed multifunctional photothermocatalytic agents for near-infrared-II light-mediated synergistic antibiofilm treatment, through modification of Lu-Bi2Te3 with Fe3O4 and poly(ethylene glycol)-b-poly(l-arginine) (PEG-b-PArg). Notably, 1064-nm laser irradiation led to photothermal/thermocatalytic effects, resulting in the synergistic generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and consequent damage to the biofilm. This treatment was based on the thermoelectric and photothermal conversion properties of Lu-Bi2Te3, the peroxidase-like catalytic capacity of Fe3O4, and the guanidinium polymer, PEG-b-PArg. Oxidative damage to biofilm was further enhanced by H2O2, resulting in the effective elimination of biofilm both in vitro and in vivo. These findings suggest that this synergistic therapeutic strategy is effective for the clinical treatment of periodontitis. STATEMENT OF SIGNIFICANCE: The current treatment for periodontitis involves time-consuming and labor-intensive clinical scaling of the teeth. The present study is the first to assess the efficacy of a photothermal catalyst for periodontitis treatment. This used near-infrared-II light at 1064 nm to induce oxidative damage in the biofilm, resulting in its degradation. The synergistic photothermal/thermoelectric effect produced deep tissue penetration and was well tolerated, and can kill the biofilm formed by periodontitis pathogens up to 5 orders of magnitude, effectively treating the biofilm-induced periodontitis.

Systematic review on dental caries preventive and managing strategies among type 2 diabetic patients.

Purpose: The purpose of this systematic review was to evaluate current evidence to prevent and manage dental caries in patients with type 2 diabetes mellitus (T2DM). Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the Participants, Intervention, Comparison, Outcomes and Study Design (PICOS) strategy was used to formulate a structured search: systematic search of PubMed, Cochrane Library, MEDLINE via Ovid, EMBASE, Scopus, Web of Science, and Lilacs without any date limit and/or language restrictions. Two independent reviewers performed data extraction and risk of bias assessments in the included studies. Data homogeneity was assessed according to interventions for treating dental caries in T2DM. Statistical analyses were performed with JMP®. Results: Two studies out of 909 were included in the systematic review. Only quantitative studies involving topical applications for management of dental caries in patients with T2DM were included. One study assessed the effect of intensive oral hygiene care program including toothbrushing and interdental cleaning using interproximal brushes and/or dental floss and supragingival debridement by dental hygienist with educational brochures in T2DM, while another investigated the immunologically active salivary substitutes with using Oral Hygiene Instructions (OHI), mouthwash, and moisturizing gel for 6 months. Intensive oral hygiene care program or immunologically active salivary substitutes with using OHI, mouthwash, and moisturizing gel for 6 months were reported to reverse/arrest dental caries in patients with T2DM. Conclusion: The current randomized controlled clinical trials demonstrated that regular extensive oral health education using interdental cleaning aids, mouthwash, moistening gel, and saliva substitutes including lactoperoxidase, lysozyme, glucose oxidase, and lactoferrin could control oral inflammation and contribute to the management of dental caries in patients with T2DM. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020197507, identifier: CRD42020197507.

Anatomical limitations and factors influencing molar distalization.

OBJECTIVES: To analyze the anatomical limitations and characteristics of maxillary and mandibular retromolar regions affecting molar distalization using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 120 qualifying patients were classified into equal groups of skeletal Class II and Class III and stratified by vertical growth pattern, age, sex, and third molar presence. The available distance along the axis of distalization and cortical bone thickness (CBT) were measured in the maxillary and mandibular retromolar regions of Class II and Class III patients, respectively. One-way analysis of variance was used to examine the effects of the factors on the measured data. RESULTS: The minimum available distance of the Class II maxilla was observed at a level 3 mm from the cementoenamel junction (CEJ), while that of the Class III mandible was at a level 9 mm from the CEJ. The average available distance at the limit level was 4.06 ± 1.93 mm in the Class II maxilla, and the average corresponding CBT was 1.00 mm. The average available distance at the limit level in the Class III mandible was 2.80 ± 1.96 mm, and the corresponding CBT was 2.24 mm. In both skeletal Class II and Class III patients, hyperdivergent groups had the least available distance for molar distalization. CONCLUSIONS: The limit for available distance in the Class II maxilla is closer to the coronal level, while that of the Class III mandible is closer to the apical level. A hyperdivergent growth pattern in a patient is indicative of less potential for molar distalization. Axial slices of CBCT images provide valuable evaluation for molar distalization regarding limit levels.

Insulin-like growth factor 1 promotes neural differentiation of human stem cells from the apical papilla.

OBJECTIVE: Insulin-like growth factor 1 (IGF1) is one of the vital factors in regenerative endodontics. Previous studies have focused on the role of IGF1 in the mineralization of dental tissues. However, the role of IGF1 in the neural differentiation of dental stem cells was little discussed. DESIGN: IGF1 was overexpressed in human stem cells from the apical papilla (hSCAPs) by lentivirus and knocked down in hSCAPs by small interfering RNA. The neural differentiation level of hSCAPs was investigated histologically by HE staining and Nissl staining after neural induction for 3 days. The expression of proteins was examined by western blot and immunofluorescence. RESULTS: IGF1 promoted neural differentiation of hSCAPs, more cell processes and Nissl-positive body stained cells. IGF1 overexpression could both promote glial differentiation in hSCAPs, characterized by the increase of S100ß and GFAP proteins, and neuronal differentiation, characterized by the increase of ßIII-tubulin and functional GAD67/vGLUT1 proteins. Conversely, IGF1 knockdown suppressed both glial and neuronal differentiation. IGF1 activated AKT to regulate the early neural differentiation of hSCAPs. CONCLUSIONS: The results indicate IGF1 could promote neural differentiation of hSCAPs by activating AKT signaling and provide a cue for the candidate of induced neural seeding cells in regenerative endodontics.

Polyphotosensitizer nanogels for GSH-responsive histone deacetylase inhibitors delivery and enhanced cancer photodynamic therapy.

Photodynamic therapy (PDT) is one of the non-invasive and selective treatment methodologies for cancer. However, many highly efficient photosensitizers (PSs) are usually low physiological solubility, limited bioavailability and tending aggregation, impeding the effectiveness of PDT, as well as cancer resistance of PDT further reduce its therapeutic effect. Though some smart delivery systems have been developed, the problem of photosensitizer leakage/release has not been completely solved. Herein, we developed a smart therapeutic nanoplatform based on polyphotosensitizer nanogel as novel nanophotosensitizers and drug carriers. Moreover, by loading of histone deacetylase inhibitors (SAHA), it allows for enhanced synergistic therapy strategy of prostate cancer via inhibiting HIF-1α and VEGF pathways of cancer cells involved in PDT resistance. Our study presents the well-designed nanoplatform of nanogel-Ce6, which could serve as a photodynamic agent without Ce6 molecules release in the responsive environment, offering the potential to encapsulate diverse functional components for smart drug release and imaging-guided combination therapy in vitro and in vivo.

Methane hydrates with a high capacity and a high formation rate promoted by biosurfactants.

Lignosulfonates, which are byproducts of the pulp and paper industry, can be used as promoters for the formation of methane hydrates with a high capacity up to 170 v/v and a high formation rate.