Deciphering the Epigenetic Code of Stem Cells Derived From Dental Tissues

Stem cells derived from dental tissues (DSCs) exhibit multipotent regenerative potential in pioneering tissue engineering regimens. The multipotency of DSCs is critically regulated by an intricate range of factors, of which the epigenetic influence is considered vital. To gain a better understanding of how epigenetic alterations are involved in the DSC fate determination, the present review overviews the current knowledge relating to DSC epigenetic modifications, paying special attention to the landscape of epigenetic modifying agents as well as the related signaling pathways in DSC regulation. In addition, insights into the future opportunities of epigenetic targeted therapies mediated by DSCs are discussed to hold promise for the novel therapeutic interventions in future translational medicine.

Single-Cell Transcriptomic Profiling of Human Dental Pulp in Sound and Carious Teeth: A Pilot Study

A comprehensive understanding of dental pulp cellular compositions and their molecular responses to infection are crucial for the advancement of regenerative dentistry. Here, we presented a pilot study of single-cell transcriptomic profiles of 6,810 pulpal cells isolated from a sound human maxillary third molar and three carious teeth with enamel and deep dental caries. We observed altered immune cell compositions of the dental pulp in deep, but not enamel ones. Differential expression analysis revealed up-regulation of several pro-inflammatory, anti-inflammatory, and mineralization-related genes in the immune and stromal cells of the deep dental caries. Making use of an algorithm for predicting cell-to-cell interactions from single-cell transcriptomic profiles, we showed an increase in cell-cell interactions between B cells, plasma cells and macrophages, and other cell types in deep dental caries, including those between TIMP1 (odontoblasts)—CD63 (myeloid cells), and CCL2 (macrophages)—ACKR1 (endothelial cells). Collectively, our work highlighted the single-cell level gene regulations and intercellular interactions in the dental pulps in health and disease.

Multivariate GWAS of Structural Dental Anomalies and Dental Caries in a Multi-Ethnic Cohort

Odontogenesis is a complex process, where disruption can result in dental anomalies and/or increase the risk of developing dental caries. Based on previous studies, certain dental anomalies tend to co-occur in patients, suggesting that these traits may share common genetic and etiological components. The main goal of this study was to implement a multivariate genome wide association study approach to identify genetic variants shared between correlated structural dental anomalies and dental caries. Our cohort (N = 3,579) was derived from the Pittsburgh Orofacial Clefts Study, where multiple dental traits were assessed in both the unaffected relatives of orofacial cleft (OFC) cases (n = 2,187) and unaffected controls (n = 1,392). We identified four multivariate patterns of correlated traits in this data: tooth agenesis, impaction, and rotation (AIR); enamel hypoplasia, displacement, and rotation (HDR); displacement, rotation, and mamelon (DRM); and dental caries, tooth agenesis and enamel hypoplasia (CAH). We analyzed each of these four models using genome-wide multivariate tests of association. No genome-wide statistically significant results were found, but we identified multiple suggestive association signals (P ≤ 10−5) near genes with known biological roles during tooth development, including ADAMTS9 and PRICKLE2 associated with AIR; GLIS3, WDR72, and ROR2 associated with HDR and DRM; ROBO2 associated with DRM; BMP7 associated with HDR; and ROBO1, SMAD2, and MSX2 associated with CAH. This is the first study to investigative genetic associations for multivariate patterns of correlated dental anomalies and dental caries. Further studies are needed to replicate these results in independent cohorts.

Effect of Temperature on Tooth Staining by 0.12% Chlorhexidine Gluconate

Introduction: Natural color of dentin is affected by many variables, including anatomical variations, age, how much dentin is exposed, or how much enamel is covering the dentin. Chlorhexidine gluconate (CHX) has been observed to cause tooth staining, especially of exposed dentin. Risk factors for CHX staining include the amount of time for CHX utilization amongst others. Interestingly, the temperature of the rinse when used has been identified as a risk factor. However, no evidence of the effect of temperature is available in the literature. The purpose of this study was to determine the effect of temperature on dentin staining due to CHX exposure.Methods: Two studies were done. The first a pilot study at room temperature to determine the time needed to establish staining solutions, a method to evaluate stain intensity, and establish the time needed to stain dentin samples in vitro. The second study exposed dentin samples on a twice daily basis to a 1 min soak in CHX at different temperatures, followed by a period in an unstimulated saliva mixed with black tea mixture. Temperatures tested were 4, 23, 37 and 50°C. Control samples were exposed to only black tea and saliva (no CHX) and tested at 23°C.Results: The pilot study found that the combination of CHX and black tea causes dentin staining. From this data the sample size needed for the second experiment was calculated, requiring 12 samples per group. Sixty dentin samples were divided amongst 5 groups. The data from this study showed significant darkening of the dentin samples over 18 days. The 4 and 23°C CHX rinses resulted in significant staining compared to the control samples. The 37 and 50°C CHX rinses did not stain significantly more than the control samples.Conclusions: Chlorhexidine has the ability to cause tooth staining in the presence of chromogens such as those in black tea. Significant darkening was observed at lower temperatures (4 and 23°C) over 18 days, therefore dental professionals may wish to advise gently warming the CHX rinse toward 37°C prior to use to reduce the risk of staining.

Additives Incorporated in Cellulose Acetate Membranes to Improve Its Performance as a Barrier in Periodontal Treatment

In this study, we prepared cellulose acetate membranes, by means of casting mold, incorporated with two additives, sodium carboxymethyl lignin and calcium glycerophosphate, in order to improve properties for periodontal applications. The membranes were characterized from the morphological, structural, thermal and mechanical point of view, as well as by physiological pH tests. The results showed that membranes with additives improve the physical-chemical and mechanical properties, especially when the two additives are present in the same membrane, which can be attributed to the important synergy between them. The most significant effects occur in increasing the thickness and decreasing the density, which reflects in the porosity of the membranes, although the added amounts do not exceed 1.4%. A 1% increase in lignin concentration does not change the thickness and density of the membrane, but that amount of lignin plus 0.4% calcium glycerophosphate increases the thickness of the membrane by 42% and decreases the density by about 6%. Although there is a decrease in mechanical properties, as observed in Young's modulus and crystallinity, the significant and intermittent increase in sample weight loss with both additives in physiological solution indicates that, in the long run, it can be used as a degradable barrier.

A Mini Review: The Potential Biomarkers for Non-invasive Diagnosis of Pulpal Inflammation

For assessing the adequacy of vital pulp therapy for an inflamed pulp, the use of non-invasive diagnostic tools is necessary to avoid further damage to the teeth. Detection of biomarkers that are indicative of the inflammatory status in pulp can be a promising tool for this purpose. These biomarkers need to be reliably correlated with pulpal inflammation and to be easily detected without pulp exposure. This mini-review article aims to review biomarkers that are present in gingival crevicular fluid (GCF) in inflamed pulp conditions. Several studies have reported the availability of various biomarkers including cytokines, proteases, elastase, neuropeptides, and growth factors. Non-invasive pulpal diagnostic methods will be useful as well to determine reversibility, irreversibility, or necrosis of inflamed pulp. These types of molecular diagnoses via analyzing the proteome have revolutionized the medical field, and are one of the most promising empirical methodologies that a clinician can utilize for the proactive identification of pulpal disease.

In-vitro Assessment of Silver Diamine Fluoride Effect on Natural Carious Dentin Microhardness

This study aimed to assess the effect of silver diamine fluoride (SDF) on natural carious dentin microhardness and the correlation between tactile sensation, fluorescence, and microhardness on carious dentin. Permanent carious teeth scored ICDAS 4–6 were longitudinally sectioned into tooth slabs exposing carious dentin on one side and sound dentin on the other. Both sides were assessed for tactile sensation (soft/leathery/firm), fluorescence (red/pink/no fluorescence) with FACE technology (SiroInspect®, Dentsply Sirona, USA), and Vickers's microhardness (VMH). Samples were randomized into 3 groups based on SDF protocol (n = 30): Control/Group A- No SDF treatment; Group B- 38% SDF (Advantage Arrest™, Elevate Oral Care®, USA); Group C- SDF with potassium iodide/KI (Riva Star, SDI, Australia). After SDF application, all samples were stored for 1 week under 100% humidity at 37°C and re-assessed for tactile sensation, fluorescence, and microhardness. Change in microhardness (ΔVMH; mean ± SD), tactile sensation (ΔT), and fluorescence (ΔF) were calculated using the difference between pre-SDF and post-SDF values. Mixed ANOVA analysis showed that ΔVMH of carious and sound surfaces were statistically significantly higher for each of the experimental groups (Group B-sound: 20.22 ± 11.98 HV, carious: 19.76 ± 9.35 HV; Group C-sound: 14.26 ± 10.11 HV, carious: 22.51 ± 7.67 HV) than the control group (Group A–sound: 7.34 ± 8.28 HV, carious: 0.69 ± 3.53 HV) (p < 0.0001). There was no statistically significant difference between the experimental groups themselves for carious surfaces (p = 0.146). On sound surfaces, Group B showed a statistically significantly higher ΔVMH than Group C (p = 0.026). There was no statistically significant interaction between type of surface and ΔVMH in Group B (p = 0.809). In Group C, sound surfaces showed a statistically significantly lower ΔVMH than carious surfaces (p < 0.0001). Spearman rank-order correlation showed a statistically significant negative correlation between ΔVMH and ΔT (rs = −0.588, p < 0.0001) and between ΔVMH and ΔF (rs = −0.269, p = 0.01). There was a statistically significant positive correlation between ΔT and ΔF (rs = 0.226, p = 0.032). In conclusion, the microhardness of SDF-treated dentin surfaces increased as compared to non-SDF-treated surfaces. SDF (Advantage Arrest™) increased microhardness of carious and sound dentin to a similar extent whereas, SDF/KI (Riva Star) increased microhardness of carious dentin more than sound dentin. An increase in microhardness was correlated with a firmer tactile sensation.

Hypoxia-Inducible Non-coding RNAs in Mesenchymal Stem Cell Fate and Regeneration

Mesenchymal stem cells (MSCs) can differentiate into multiple cell lines, which makes them an important source of cells for tissue engineering applications. They are defined by the capability to renew themselves and maintain pluripotency. This ability is modulated by the balance between complex cues from cellular microenvironment. Self-renewal and differentiation abilities are regulated by particular microenvironmental signals. Oxygen is considered to be an important part of cell microenvironment, which not only acts as a metabolic substrate but also a signal molecule. It has been proved that MSCs are hypoxic in the physiological environment. Signals from MSCs' microenvironment or niche which means the anatomical location of the MSCs, maintain the final properties of MSCs. Physiological conditions like oxygen tension are deemed to be a significant part of the mesenchymal stem cell niche, and have been proved to be involved in modulating embryonic and adult MSCs. Non-coding RNAs (ncRNAs), which play a key role in cell signal transduction, transcription and translation of genes, have been widely concerned as epigenetic regulators in a great deal of tissues. With the rapid development of bioinformatics analysis tools and high-throughput RNA sequencing technology, more and more evidences show that ncRNAs play a key role in tissue regeneration. It shows potential as a biomarker of MSC differentiation. In this paper, we reviewed the physiological correlation of hypoxia as a unique environmental parameter which is conducive to MSC expansion and maintenance, discussed the correlation of tissue engineering, and summarized the influence of hypoxia related ncRNAs on MSCs' fate and regeneration. This review will provide reference for future research of MSCs' regeneration.

Assessments of Prevalence of Ponticulus Posticus, Atlas Posterior Arch Deficiency, Sella Turcica Bridging, Maxillary Canine Impaction, and Associations Among Them in 500 CBCTs of Italian Orthodontic Patients

Background: The ponticulus posticus (PP) is an important anomaly of the atlas (C1 vertebra) with a complete or partial bone bridge that transforms the groove of the vertebral artery (VA) into a canal (arcuate foramen). The aim was to retrospectively determine prevalence of PP evaluating morphological features and the possible association with other dentoskeletal anomalies in the midface and neck area such as maxillary canine impaction (MCI), atlas posterior arch deficiency (APAD), and sella turcica bridging (SB).Methods: This study was conducted in the Department of Medical, Oral and Biotechnological Sciences of the University “G. D'Annunzio” in Chieti. The detection of PP was performed on 500 patients with cone beam CT (CBCT) images (6 to 87 years).Results: Analysis revealed the presence of uni- and bi-lateral PP in 110 patients (22%): 24 (4.8%) patients with bilateral complete PP, 12 (2.4%) patients with complete PP on the left, 6 (1.2%) patients with complete PP on the right, 8 (1.6%) patients with complete PP on the right and partial PP on the left, 6 (1.2%) patients with complete PP on the left and partial PP on the right, 26 (5.2%) patients with partial bilateral PP, 18 (3.6%) patients with partial left PP, and 10 (2%) patients with partial PP on the right. The Chi-squared statistic confirmed that there are significant associations between MCI and PP (p = 0.020) and between SB and MCI (p <0.00001). No correlation between chronological age and presence of the PP (p = 0.982), between chronological age and morphotypes of the PP (p = 0.779), between APAD and the PP (p = 0.0757), between SB and the PP (p = 0.111), and between APAD and MCI (p = 0.222) were found.Conclusion: This observational study showed how bilateral partial variant and bilateral complete variant are the most represented morphotypes in all the age groups. The prevalence of MCI is positively associated with PP and with SB.

Nature of the Interplay Between Periodontal Diseases and COVID-19

The coronavirus disease 2019 (COVID-19) is mostly a mild condition, however, in some patients, it could progress into a severe and even fatal disease. Recent studies have shown that COVID-19 infection and severity could be associated with the presence of periodontitis, one of the most prevalent chronic diseases. This association could be explained by the fact that periodontitis and COVID-19 share some common risk factors that included chronic diseases, such as diabetes and hypertension as well as conditions such as age, sex, and genetic variants. Another possible explanation could be the systemic inflammation and the aspiration of periodontopathogens seen in patients with periodontitis, which could have a synergism with the virus or compromise the reaction of the body against COVID-19. This narrative review explores the nature of these associations, the evidence behind them, and their implications.