Evaluation of dental pulp stem cells response to flowable nano-hybrid dental composites: A comparative analysis.

BACKGROUND: Flowable resin composites (FRC) are tooth-colored restorative materials that contain a lower filler particle content, and lower viscosity than their bulk counterparts, making them useful for specific clinical applications. Yet, their chemical makeup may impact the cellular population of the tooth pulp. This in-vitro study assessed the cytocompatibility and odontogenic differentiation capacity of dental pulp stem cells (DPSCs) in response to two recent FRC material extracts. METHODS: Extracts of the FRC Aura easyflow (AEF) and Polofil NHT Flow (PNF) were applied to DPSCs isolated from extracted human teeth. Cell viability of DPSCs was assessed using MTT assay on days 1, 3 and 7. Cell migration was assessed using the wound healing assay. DPSCs' capacity for osteo/odontogenic differentiation was assessed by measuring the degree of mineralization by Alizarin Red S staining, alkaline phosphatase enzyme (ALP) activity, and monitoring the expression of osteoprotegerin (OPG), RUNX Family Transcription Factor 2 (RUNX2), and the odontogenic marker dentin sialophosphoprotein (DSPP) by RT-PCR. Monomer release from the FRC was also assessed by High-performance liquid chromatography analysis (HPLC). RESULTS: DPSCs exposed to PNF extracts showed significantly higher cell viability, faster wound closure, and superior odontogenic differentiation. This was apparent through Alizarin Red staining of calcified nodules, elevated alkaline phosphatase activity, and increased expression of osteo/odontogenic markers. Moreover, HPLC analysis revealed a higher release of TEDGMA, UDMA, and BISGMA from AEF. CONCLUSIONS: PNF showed better cytocompatibility and enhancement of odontogenic differentiation than AEF.

Mechanism underlying the anti-diabetic potential of bee venom as compared to bone marrow mesenchymal stem cells in the diabetic rat tongue.

BACKGROUND: Diabetes mellitus (DM) is a critical chronic metabolic disease. Several treatment modalities are currently under investigation. Both bee venom (BV) and bone marrow mesenchymal stem cells (BMSCs) can possibly offer an approach for treating type I diabetes. OBJECTIVES: The aim of the present study was to investigate the mechanism underlying the anti-diabetic effect of BV as compared to BMSCs on the tongue mucosa of diabetic rats. MATERIAL AND METHODS: A total of 52 male albino rats were used in the current study. The rats were randomly assigned into 4 groups: group 1 (control); group 2 (streptozocin (STZ)); group 3 (BV-treated); and group 4 (BMSC-treated). Diabetes mellitus was induced via an intraperitoneal (IP) injection of STZ in the rats from groups 2, 3 and 4. Following the diagnosis of DM, the rats in group 3 were injected with a daily dose of 0.5 mg/kg of BV, while the rats in group 4 were treated with a single injection of BMSCs. All rats were euthanized after 4 weeks, and their tongues were dissected and divided into halves. The right halves of the tongues were utilized for the histological examination, followed by morphometric analysis. In contrast, the left halves were used to detect the local gene expression of transforming growth factor beta 1 (TGF-ß1) and vascular endothelial growth factor (VEGF). RESULTS: Group 2 revealed marked disruption in the morphology of the fungiform and filiform papillae, and atrophic epithelial changes in both dorsal and ventral surface epithelium as compared to other groups. Group 4 showed a significantly larger number of taste buds, and a higher gene expression of TGF-ß1 and VEGF as compared to groups 2 and 3. Additionally, BV and BMSCs effectively increased the thickness of dorsal and ventral surface epithelium as compared to group 2. CONCLUSIONS: Treatment with BMSCs was associated with significant improvement in the morphology and number of lingual epithelial cells and taste buds in the tongues of diabetic rats as compared to BV-treated rats, which was due to the local upregulation of TGF-ß1 and VEGF gene expression.

Molecular Basis beyond Interrelated Bone Resorption/Regeneration in Periodontal Diseases: A Concise Review.

Periodontitis is the sixth most common chronic inflammatory disease, destroying the tissues supporting the teeth. There are three distinct stages in periodontitis: infection, inflammation, and tissue destruction, where each stage has its own characteristics and hence its line of treatment. Illuminating the underlying mechanisms of alveolar bone loss is vital in the treatment of periodontitis to allow for subsequent reconstruction of the periodontium. Bone cells, including osteoclasts, osteoblasts, and bone marrow stromal cells, classically were thought to control bone destruction in periodontitis. Lately, osteocytes were found to assist in inflammation-related bone remodeling besides being able to initiate physiological bone remodeling. Furthermore, mesenchymal stem cells (MSCs) either transplanted or homed exhibit highly immunosuppressive properties, such as preventing monocytes/hematopoietic precursor differentiation and downregulating excessive release of inflammatory cytokines. In the early stages of bone regeneration, an acute inflammatory response is critical for the recruitment of MSCs, controlling their migration, and their differentiation. Later during bone remodeling, the interaction and balance between proinflammatory and anti-inflammatory cytokines could regulate MSC properties, resulting in either bone formation or bone resorption. This narrative review elaborates on the important interactions between inflammatory stimuli during periodontal diseases, bone cells, MSCs, and subsequent bone regeneration or bone resorption. Understanding these concepts will open up new possibilities for promoting bone regeneration and hindering bone loss caused by periodontal diseases.

Evaluation of lingual mucosa toxicity and recovery follow-up in rats, following sub-chronic exposure to titanium dioxide nanoparticles.

BACKGROUND: Nanosized titanium dioxide (TiO2) particles are among the most widely used nanoparticles (NPs) worldwide due to their unique properties. The lingual mucosa is still neglected in terms of risk assessment with respect to the NP uptake. OBJECTIVES: The aim of this study was to evaluate the effect of intragastric administration of TiO2 NPs on the mucous membranes of the tongues of albino rats, as well as the potential benefits of a 4-week recovery period. MATERIAL AND METHODS: Twenty-one male albino rats were randomly divided into 3 groups (n = 7 per group). Group I served as a control group and received saline intragastrically daily for 30 days. The experimental groups included group II, which received TiO2 NPs in the amount of 50 mg/kg of body weight (b.w.) intragastrically daily for 30 days, and group III, which also received TiO2 NPs in the amount of 50 mg/kg b.w. intragastrically daily for 30 days, and then was allowed to recover for 4 weeks. Tongue specimens were collected for histological, immunohistochemical and morphometric examinations. RESULTS: The TiO2 NP group II showed significant atrophic and degenerative changes in the tongue mucosa, which included reduced epithelial thickness in the ventral surface, with disfigurement in the filiform and fungiform papillae. Weak B cell lymphoma-2 (Bcl-2) immunoreactivity was also noted. The 4-week recovery group displayed improvement in the histological picture, with moderate to strong Bcl-2 immunoreactivity in the epithelial cell layers and the underlying connective tissue. CONCLUSIONS: The use of TiO2 NPs caused severe histological and apoptotic changes in the filiform and fungiform papillae, and the ventral surface of the tongue of the rats, while allowing recovery minimized the toxic effect of the NPs.

The effect of unhealthy dietary habits on the incidence of dental caries and overweight/obesity among Egyptian school children (A cross-sectional study).

Background: Obesity and dental caries are public health problems in Egypt. Factors such as unhealthy diet, poor oral hygiene, and physical inactivity can play a major role in both problems. This study was carried out to illuminate the mutual unhealthy dietary risk factors associated with the incidence of both health conditions. Methods: Between 1 October 2020 and 1 July 2021, 369 Egyptian children (5-10 years) were examined. Dental status was assessed using decayed, missing/extracted, and filled tooth indices (dmft, deft, and DMFT) for deciduous, mixed, and permanent dentitions, respectively. Moreover, the lifestyle, food habits, and body mass index (BMI) were recorded. Results: A total of 342 (93.7%) of the included subjects suffered from caries, and only 27(7.3%) were caries-free. Based on BMI percentiles, 247 (66.9%) of the youngsters were overweight/obese, while 122 (33.1%) had normal weight. The mean dmft was 6.9 (±4.6), deft 4.2 (±3.3), and DMFT 0.1 (±1.7). In the primary dentition, a significant positive correlation was detected between dmft and BMI, legumes, sweetened milk and juice, soft drinks, and desserts, while a significant negative correlation was detected between dmft/deft, meat/poultry/fish, fresh fruits, and vegetables. A significant positive correlation was detected between deft and BMI, sweetened milk and juice, ice cream, candies, and crackers. In the permanent dentition, a significant positive correlation was detected between age, soft drinks, sweetened juice, desserts, and DMFT, while a significant negative correlation was detected with fresh fruits and vegetables. BMI was significantly negatively correlated with a healthy lifestyle, meat/poultry/fish consumption, and fresh fruits and vegetables while positively correlated with legumes, ice cream, soft drinks, granulated sugars, desserts, fast food, and caffeinated drinks. Conclusion: Overweight/obesity was positively correlated with primary dentition dental caries. Desserts (sweetened snacks) and soft drinks could be the common risk factors associated with high caries and overweight/obesity incidence among Egyptian school children; conversely, consumption of fruits and vegetables could hinder both health conditions. Moreover, sweetened juices were associated with primary and permanent dental caries.

Effect of Polymeric Matrix Stiffness on Osteogenic Differentiation of Mesenchymal Stem/Progenitor Cells: Concise Review.

Mesenchymal stem/progenitor cells (MSCs) have a multi-differentiation potential into specialized cell types, with remarkable regenerative and therapeutic results. Several factors could trigger the differentiation of MSCs into specific lineages, among them the biophysical and chemical characteristics of the extracellular matrix (ECM), including its stiffness, composition, topography, and mechanical properties. MSCs can sense and assess the stiffness of extracellular substrates through the process of mechanotransduction. Through this process, the extracellular matrix can govern and direct MSCs' lineage commitment through complex intracellular pathways. Hence, various biomimetic natural and synthetic polymeric matrices of tunable stiffness were developed and further investigated to mimic the MSCs' native tissues. Customizing scaffold materials to mimic cells' natural environment is of utmost importance during the process of tissue engineering. This review aims to highlight the regulatory role of matrix stiffness in directing the osteogenic differentiation of MSCs, addressing how MSCs sense and respond to their ECM, in addition to listing different polymeric biomaterials and methods used to alter their stiffness to dictate MSCs' differentiation towards the osteogenic lineage.

Biocompatibility assessment of different root-end filling materials implanted subcutaneously in rats: An in vivo study.

BACKGROUND: Root-end filling materials are used in surgical endodontic treatment to seal the teeth periapically. Ideally, these materials should prevent bacterial leakage by tightly sealing the canal, be biocompatible with the periapical tissues, and preferably stimulate the regeneration of dentin, contributing to the success of treatment. OBJECTIVES: The purpose of this study was to evaluate and compare the biocompatibility of the GuttaFlow® Bioseal cement in relation to MTA Angelus® and Zical® after implantation into the subcutaneous tissue of rats. MATERIAL AND METHODS: Eighteen male albino rats were used in the study. Four polyethylene tubes were implanted in the backs of the rats (3 tubes containing the test materials and 1 empty tube as a control). Nine animals were sacrificed at each interval of 7 and 30 days, and the implants were removed with the surrounding tissue. The samples were evaluated for stromal inflammatory response, fibrous tissue formation, vascular reactivity, and the presence of multinucleated giant cells (MNGCs). RESULTS: On day 7, the capsules in all subgroups revealed moderate to severe inflammatory reactions with the presence of inflammatory cells, multiple irregular collagen fibers, dilated blood vessels, and MNGCs. However, on day 30, tissue organization was more evident with a reduction in the inflammatory response. In this time interval, the tissue in contact with GuttaFlow Bioseal showed progressive healing with a wellformed fibrous capsule. Conversely, the tissue close to MTA Angelus revealed a fibrous capsule of limited organization with mild pericapsular fibrosis and vascular congestion. Zical showed a mild to moderate persistent inflammatory reaction and vascular reactivity. CONCLUSIONS: The 3 cements demonstrated more severe irritation at the beginning that became milder with time. GuttaFlow Bioseal yielded better tissue organization than MTA Angelus and Zical. Thus, these findings strongly suggest that GuttaFlow Bioseal is a promising material for root-end filling.

Hydrogels and Dentin-Pulp Complex Regeneration: From the Benchtop to Clinical Translation.

Dentin-pulp complex is a term which refers to the dental pulp (DP) surrounded by dentin along its peripheries. Dentin and dental pulp are highly specialized tissues, which can be affected by various insults, primarily by dental caries. Regeneration of the dentin-pulp complex is of paramount importance to regain tooth vitality. The regenerative endodontic procedure (REP) is a relatively current approach, which aims to regenerate the dentin-pulp complex through stimulating the differentiation of resident or transplanted stem/progenitor cells. Hydrogel-based scaffolds are a unique category of three dimensional polymeric networks with high water content. They are hydrophilic, biocompatible, with tunable degradation patterns and mechanical properties, in addition to the ability to be loaded with various bioactive molecules. Furthermore, hydrogels have a considerable degree of flexibility and elasticity, mimicking the cell extracellular matrix (ECM), particularly that of the DP. The current review presents how for dentin-pulp complex regeneration, the application of injectable hydrogels combined with stem/progenitor cells could represent a promising approach. According to the source of the polymeric chain forming the hydrogel, they can be classified into natural, synthetic or hybrid hydrogels, combining natural and synthetic ones. Natural polymers are bioactive, highly biocompatible, and biodegradable by naturally occurring enzymes or via hydrolysis. On the other hand, synthetic polymers offer tunable mechanical properties, thermostability and durability as compared to natural hydrogels. Hybrid hydrogels combine the benefits of synthetic and natural polymers. Hydrogels can be biofunctionalized with cell-binding sequences as arginine-glycine-aspartic acid (RGD), can be used for local delivery of bioactive molecules and cellularized with stem cells for dentin-pulp regeneration. Formulating a hydrogel scaffold material fulfilling the required criteria in regenerative endodontics is still an area of active research, which shows promising potential for replacing conventional endodontic treatments in the near future.

Induced Pluripotent Stem Cells in Dental and Nondental Tissue Regeneration: A Review of an Unexploited Potential.

Cell-based therapies currently represent the state of art for tissue regenerative treatment approaches for various diseases and disorders. Induced pluripotent stem cells (iPSCs), reprogrammed from adult somatic cells, using vectors carrying definite transcription factors, have manifested a breakthrough in regenerative medicine, relying on their pluripotent nature and ease of generation in large amounts from various dental and nondental tissues. In addition to their potential applications in regenerative medicine and dentistry, iPSCs can also be used in disease modeling and drug testing for personalized medicine. The current review discusses various techniques for the production of iPSC-derived osteogenic and odontogenic progenitors, the therapeutic applications of iPSCs, and their regenerative potential in vivo and in vitro. Through the present review, we aim to explore the potential applications of iPSCs in dental and nondental tissue regeneration and to highlight different protocols used for the generation of different tissues and cell lines from iPSCs.

Dental Stem Cell-Derived Secretome/Conditioned Medium: The Future for Regenerative Therapeutic Applications.

Regenerative medicine literature has proposed mesenchymal stem/progenitor cell- (MSC-) mediated therapeutic approaches for their great potential in managing various diseases and tissue defects. Dental MSCs represent promising alternatives to nondental MSCs, owing to their ease of harvesting with minimally invasive procedures. Their mechanism of action has been attributed to their cell-to-cell contacts as well as to the paracrine effect of their secreted factors, namely, secretome. In this context, dental MSC-derived secretome/conditioned medium could represent a unique cell-free regenerative and therapeutic approach, with fascinating advantages over parent cells. This article reviews the application of different populations of dental MSC secretome/conditioned medium in in vitro and in vivo animal models, highlights their significant implementation in treating different tissue' diseases, and clarifies the significant bioactive molecules involved in their regenerative potential. The analysis of these recent studies clearly indicate that dental MSCs' secretome/conditioned medium could be effective in treating neural injuries, for dental tissue regeneration, in repairing bone defects, and in managing cardiovascular diseases, diabetes mellitus, hepatic regeneration, and skin injuries, through regulating anti-inflammatory, antiapoptotic, angiogenic, osteogenic, and neurogenic mediators.

Mesenchymal Stem/Progenitor Cells: The Prospect of Human Clinical Translation.

Mesenchymal stem/progenitor cells (MSCs) are key players in regenerative medicine, relying principally on their differentiation/regeneration potential, immunomodulatory properties, paracrine effects, and potent homing ability with minimal if any ethical concerns. Even though multiple preclinical and clinical studies have demonstrated remarkable properties for MSCs, the clinical applicability of MSC-based therapies is still questionable. Several challenges exist that critically hinder a successful clinical translation of MSC-based therapies, including but not limited to heterogeneity of their populations, variability in their quality and quantity, donor-related factors, discrepancies in protocols for isolation, in vitro expansion and premodification, and variability in methods of cell delivery, dosing, and cell homing. Alterations of MSC viability, proliferation, properties, and/or function are also affected by various drugs and chemicals. Moreover, significant safety concerns exist due to possible teratogenic/neoplastic potential and transmission of infectious diseases. Through the current review, we aim to highlight the major challenges facing MSCs' human clinical translation and shed light on the undergoing strategies to overcome them.

The potential impact of age, gender, body mass index, socioeconomic status and dietary habits on the prevalence of dental caries among Egyptian adults: a cross-sectional study.

Background: Dental caries is a major public health problem and the most widespread chronic disease to affect individuals throughout their lifetime. Little information exists about the prevalence of dental caries among Egyptian adults. Therefore, this study investigated the dental caries experience among Egyptian adults in correlation with different risk factors. Methods: A total of 359 Egyptian adults (age range, 18-74 years) were examined over a period of 3 months, starting on the 15 th of November 2017 until the 13 th of January 2018. Socio-demographic data, brushing frequency, body mass index (BMI) and eating habits were recorded and collected using a questionnaire. Dental examination was performed using the Decayed, Missing and Filled tooth (DMFT) index. Results: In total, 86.63% of participants had dental caries experience. Of the participants, 60.45%, 48.47% and 55.43% had at least one decayed, missing and filled tooth, respectively. The mean number of decayed, missing, filled or DMFT for the whole sample were 2.4±3.6, 1.98±3.99, 1.79±2.45, 6.09±5.7, respectively. Decayed teeth were inversely correlated with socio-economic status (SES), education level, brushing frequency and milk consumption and positively correlated with grains, junk food and soda drinks consumption. Missing teeth were inversely correlated with SES, education level and brushing frequency, while positively correlated with age, BMI and caffeinated drink consumption. Conversely, filled teeth were positively correlated with age, BMI, SES and education level, while negatively correlated with grains and sugars in drinks. Conclusion: The present study clarifies that age, BMI, SES, education level and brushing frequency are risk factors significantly associated with dental caries prevalence amongst Egyptian adults. Egyptian adults' dietary habits might lead to obesity, which indirectly causes dental caries rather than directly as in children.

The prevalence of dental caries among Egyptian children and adolescences and its association with age, socioeconomic status, dietary habits and other risk factors. A cross-sectional study.

Background: Dental caries is a chronic, multifactorial disease, with limited data available for the Egyptian population. The aim of this study is to assess the prevalence of dental caries among Egyptian children and adolescents in correlation with age, gender, body mass index, socioeconomic status, parental education, biological risk factors and dietary habits. Methods: A total number of 369 Egyptian children and adolescents (age ranges from 3-18 years) were examined over the period from 15 th November 2017 to 13 th January 2018. Socio-demographic data, oral hygiene measures and dietary habits for children were recorded. Dental status was analyzed using decayed, missing and filled tooth index (dmft) for deciduous dentition and (DMFT) index for permanent dentition. For mixed dentition (deft) index was used, d (decayed tooth indicated for filling), e (decayed tooth indicated for extraction) and f (filled tooth). Results: 74% of the children had dental caries with mean dmft: 3.23±4.07; deft: 4.21±3.21; DMFT: 1.04±1.56. In primary dentition, dmft of the children was positively correlated with age, beans, candies, crackers, chocolates and inversely correlated with gender, socio-economic status (SES), parental education, brushing frequency of the parent, brushing frequency of the parent to the child teeth, brushing frequency of the child and consumption of eggs, fruits/vegetables, milk and milk products. In mixed dentition, deft was positively correlated with candies, crackers, citric juices, while negatively correlated with age, SES, parental education, brushing frequency of the parent to the child, brushing frequency of the child, fruits/vegetables. In permanent dentition, DMFT in children was positively correlated with age and chocolates while not correlated with any of the remaining risk factors. Conclusion: The present study clarifies the significant risk factors associated with dental caries amongst Egyptian children. This will help in planning strategies to prevent and treat such disease.

The occurrence of periodontal diseases and its correlation with different risk factors among a convenient sample of adult Egyptian population: a cross-sectional study.

Background: Even though extensive studies on the prevalence of periodontal diseases in various populations worldwide have been carried out, data for the Egyptian population is limited.  The present study was carried out to evaluate the occurrence and the severity of periodontal disease and its correlation with different risk factors. Methods: Periodontal examination was performed on 343 adults attending the outpatient clinics of the Faculty of Dentistry, Cairo University, as well as three private clinics. Socio-demographic data, brushing frequency, body mass index (BMI) and dietary habits were recorded using a questionnaire. Results: It was found that 58.9% of participants had calculus deposits. The occurrence of periodontitis was 89.8%, where 70.8% of participants had stage I and 15.2% had stage II, while only 4.4% and 2.05% suffered from stage III and stage IV, respectively. Calculus was positively correlated with age, grains, and sugar in drinks and negatively correlated with socioeconomic status, education level, brushing frequency and milk. Calculus was not correlated with gender and BMI. Periodontitis was positively correlated with age, carbohydrates other than bread, grains, and crackers, as well as caffeinated drinks, while negatively correlated with gender, socioeconomic status, brushing frequency. Periodontitis was not correlated with BMI or education level. Conclusion: The present study clarifies that age, brushing frequency, carbohydrates and caffeinated drinks consumption are significant factors influencing the occurrence and the severity of periodontal diseases.

Healing capacity of bone marrow mesenchymal stem cells versus platelet-rich fibrin in tibial bone defects of albino rats: an in vivo study.

Background: Various techniques for tissue engineering have been introduced to aid the regeneration of defective or lost bone tissue. The aim of this study was to compare the in vivo bone-forming potential of bone marrow mesenchymal stem cells (BM-MSCs) and platelet-rich fibrin (PRF) on induced bone defects in rats' tibiae. Methods: In total, one defect of 3-mm diameter was created in each tibia of 36 Wistar male rats. There were two groups: group A, left tibia bone defects that received PRF; and group B, right tibia bone defects of the same animal that received BM-MSCs loaded on a chitosan scaffold. Subsequently, Scanning electron microscope/energy-dispersive X-ray (SEM/EDX) analyses was performed at 3 and 10 days, and 3 weeks post­implantation and following euthanasia; (n=12). Results: The EDX analysis performed for each group and time point revealed a significant increase in the mean calcium and phosphorous weight percentage in the BM-MSC-treated group relative to the PRF-treated group at all-time intervals (P < 0.05). Moreover, the mean calcium and phosphorus weight percentage increased as time progressed since the surgical intervention in the PRF-treated and BM-MSCs groups (P < 0.05). Conclusions: In the present study, both BM-MSCs and PRF were capable of healing osseous defects induced in a rat tibial model. Yet, BM-MSCs promoted more adequate healing, with higher mean calcium and phosphorous weight percentages than PRF at all-time points, and showed greater integration into the surrounding tissues than PRF.