Journal of Dental Research

Epidemiology is experiencing a significant shift toward the utilization of big data for health monitoring and decision-making. This article discusses the recent example of the World Health Organization (WHO) global oral health status report and regional summaries, which faced criticisms due to its reliance on big data from the Global Burden of Disease (GBD) study. We address the arguments for and against the use of big data in epidemiology and provide an assessment of the value and limitations of big data epidemiology. Moreover, we provide recommendations as to how the oral health community should reconcile traditional epidemiologic approaches with big data and advanced data analytics. This Perspective article highlights the challenges of the current epidemiologic landscape, the potential of big data, and the need for a balanced approach to data utilization in epidemiology.

Artificial intelligence systems (AISs) gain relevance in dentistry, encompassing diagnostics, treatment planning, patient management, and therapy. However, questions about the generalizability, fairness, and transparency of these systems remain. Regulatory and governance bodies worldwide are aiming to address these questions using various frameworks. On March 13, 2024, members of the European Parliament approved the Artificial Intelligence Act (AIA), which emphasizes trustworthiness and human-centeredness as relevant aspects to regulate AISs beyond safety and efficacy. This review presents the AIA and similar regulatory and governance efforts in other jurisdictions and lays out that regulations such as the AIA are part of a complex ecosystem of interdependent and interwoven legal requirements and standards. Current efforts to regulate dental AISs require active input from the dental community, with participation of dental research, education, providers, and patients being relevant to shape the future of dental AISs.

Apoptosis is the most prominent mode of programmed cell death and is necessary for the maintenance of tissue homeostasis. During cell apoptosis, a distinctive population of extracellular vesicles is generated, termed apoptotic vesicles (apoVs). ApoVs inherit a variety of biological molecules such as proteins, RNAs, nuclear components, lipids, and gasotransmitters from their parent cells. ApoVs have shown promising therapeutic potential for inflammation, tumors, immune disorders, and tissue regeneration. In addition, apoVs can be used as drug carriers, vaccine development, and disease diagnosis. Recently, apoVs have been used in clinical trials to treat a variety of diseases, such as temporomandibular joint osteoarthritis and the regeneration of functional alveolar bone. Here, we review the history of apoV research, current preclinical and clinical studies, and the potential issues of apoV application.

The management of oral leukoplakia (OL) is challenging because of a high risk for recurrence and malignant transformation (MT), and recurrent OL is associated with a higher risk of MT than nonrecurrent OL. The present meta-analysis aimed to examine the association between OL recurrence and surgical techniques used for their management as well as their clinicopathological factors. Electronic searches were conducted in EMBASE, PubMed, Scopus, and Web of Science to retrieve studies reporting OL recurrence after surgery. The pooled proportion of OL recurrence after surgical excision was estimated. Subgroup analyses were conducted based on the surgical technique, data type, grades of epithelial dysplasia, anatomical subsites, clinical type and size of the lesion, surgical margin, and risk habits. Meta-regression analyses were conducted to identify the association between age, sex, and follow-up duration and OL recurrence. The risk of MT based on the recurrence status was also estimated. A network meta-analysis was performed to determine the surgical modality associated with the least OL recurrence. Eighty studies with a total of 7,614 samples and various surgical modalities (laser-based techniques, conventional scalpel surgery, cryosurgery, and photodynamic therapy) were included in the meta-analysis. A pooled proportion of recurrence of 22% was observed. Laser-based surgeries resulted in fewer OL recurrences than other surgical modalities, and the combination of laser excision and vaporization was identified to be the best treatment approach. OL in the retromolar area and multiple sites, nonhomogeneous OL, advanced age, female sex, inadequate surgical margin, retrospective data, and betel quid chewing habit were significantly associated with higher OL recurrence. Recurrent OL showed a 7.39 times higher risk of MT than nonrecurrent OL. These results suggest that the combination of laser excision and vaporization might reduce OL recurrence. Furthermore, OL in older patients, females, and nonhomogeneous OL need close monitoring after any surgical therapy.

Adequate and transparent reporting is necessary for critically appraising published research. Yet, ample evidence suggests that the design, conduct, analysis, interpretation, and reporting of oral health research could be greatly improved. Accordingly, the Task Force on Design and Analysis in Oral Health Research—statisticians and trialists from academia and industry—identified the minimum information needed to report and evaluate observational studies and clinical trials in oral health: the OHStat Guidelines. Drafts were circulated to the editors of 85 oral health journals and to Task Force members and sponsors and discussed at a December 2020 workshop attended by 49 researchers. The guidelines were subsequently revised by the Task Force’s writing group. The guidelines draw heavily from the Consolidated Standards for Reporting Trials (CONSORT), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and CONSORT harms guidelines and incorporate the SAMPL guidelines for reporting statistics, the CLIP principles for documenting images, and the GRADE indicating the quality of evidence. The guidelines also recommend reporting estimates in clinically meaningful units using confidence intervals, rather than relying on P values. In addition, OHStat introduces 7 new guidelines that concern the text itself, such as checking the congruence between abstract and text, structuring the discussion, and listing conclusions to make them more specific. OHStat does not replace other reporting guidelines; it incorporates those most relevant to dental research into a single document. Manuscripts using the OHStat guidelines will provide more information specific to oral health research.

Fatigue of temporomandibular joint (TMJ) tissues reflects the effects of magnitude (energy density; ED) and frequency of loading (jaw muscle duty factor; DF). This observational study measured these variables and tested for differences in mechanobehavior scores (MBS = ED² × DF) and component variables in subjects with and without TMJ disc displacement (±D). In accordance with Institutional Review Board and STROBE guidelines, written informed consent was obtained, and examination and imaging protocols identified eligible adult subjects. Specifically, magnetic resonance imaging was used to assign subjects’ TMJs to ±D groups. Subjects were trained to record in-field jaw muscle activities, from which DFs (percentage of recording time) were determined. EDs (mJ/mm³) were estimated using modeled TMJ loads and in vivo dynamic stereometry. Multivariate analysis of variance, post hoc independent t tests, and K-means cluster analysis identified significant group differences (P < 0.05). Of 242 individuals screened, 65 females (TMJs: 78 +D, 52 −D) and 53 males (TMJs: 39 +D, 67 −D) participated. Subjects produced 312 daytime and 319 nighttime recordings of average duration 6.0 ± 0.2 h and 7.6 ± 0.1 h, respectively, and 219 (114 right, 105 left) intact dynamic stereometry recordings. Average EDs were 2-fold and significantly larger in +D than −D TMJs (P < 0.0001). DFs were on average 3-fold larger during the daytime versus nighttime for both masseter and temporalis muscles and 1.8- and 3.0-fold larger for the masseter versus temporalis muscle during the daytime and nighttime, respectively. Daytime masseter MBSs for +D TMJs in females were the largest overall at 621 ± 212 (mJ/mm³)²% and 2- to 43-fold larger versus −D TMJs in both sexes during daytime and nighttime. Cluster analysis (P < 0.0001) identified groups 2 and 3, which comprised 87% +D TMJs and had average MBSs 21-fold larger than group 1. The results show MBS as a potential biomarker to predict homeostasis versus progression or reversal of degenerative TMJ structural changes.

The coloring process of monolithic dental zirconia caused considerable debate on the possible effects of different coloring methods. The main objective of this study was to investigate the influence of pigments in 3 multilayer 5-mol% yttria partially stabilized zirconia (5Y-PSZ) disks (Lava Esthetic A2 [Zr-AGG_A2] and Bleach [Zr-AGG_BL], both 3M Oral Care, and Katana STML A2 [Zr-NoAGG], Kuraray Noritake). The influence of pigment addition on the translucency parameter (TP₀₀), fracture toughness, Vickers hardness, biaxial strength, and hydrothermal stability was assessed and correlated with the microstructure and phase composition. The pigment composition and distribution were evaluated by light and fluorescence microscopy, electron probe microanalysis, and nano–scanning electron microscopy. The chemical and phase composition and aging behavior were assessed using X-ray fluorescence and X-ray diffraction, respectively, while the aging sensitivity of the pigments was evaluated using micro-Raman spectroscopy. In contrast to Zr-NoAGG, possessing a typical 5Y-PSZ microstructure, the pigment additions in both Zr-AGG_A2/BL zirconia resulted in large yellow and blue fluorescent Er-, Hf-, and Al-containing agglomerates composed of small grains (0.57 µm and 0.38 µm, respectively, vs. 0.92 µm for the surrounding grains) with lower Y₂O₃ content. Zr-AGG_A2 had the lowest aging resistance, with transformation degradation occurring exclusively within the pigment agglomerates. All zirconia grades had a high Y₂O₃ content (4.2%–5.7 mol%) tetragonal ZrO₂ phase and a high (42%–55 wt%) cubic ZrO₂ phase content. Although no statistical differences were measured for hardness and toughness, Zr-NoAGG had a significantly higher TP₀₀, higher flexural strength, and lower mechanical reliability compared to both Zr-AGG_A2/BL zirconia. The rare-earth oxide-containing zirconia agglomerates that were added as pigments to the multilayered monolithic Zr-AGG_A2/BL zirconia are the cause for their lower optical and mechanical properties and reduced aging resistance.

Parkinson’s disease (PD) is a neurodegenerative condition characterized by the progressive and selective loss of dopaminergic (DAergic) neurons in the midbrain. The replacement of neuromelanin (NM)–containing DAergic neurons in the substantia nigra and the enhancement of NM concentration could offer a promising and safe approach to treating PD symptoms. The objective of this study was to investigate and compare the potential of human periapical-cysts mesenchymal stem cells (hPCy-MSCs) and dental pulp stem cells (DPSCs) to differentiate into DAergic NM-producing neurons and to generate functional 3-dimensional (3D) midbrain-like organoids in vitro. We assessed the changes in morphology and behavior of neuron-like cells (NLCs) as well as the expression of molecular markers characterizing the DAergic neurons. Furthermore, we observed electrically active and functionally mature DAergic neurons by means of electrophysiological assays, NM dosage assays, and the quantification of dopamine release by high-performance liquid chromatography. Our results demonstrate for the first time that both hPCy-MSCs and DPSCs are capable of differentiating into NLCs, further confirmed by the increase in lactate levels in the medium of cells exposed to neurogenic conditions. Importantly, we have induced such NLCs to further differentiate into functional DAergic NM-producing neurons. Finally, 3D midbrain-like organoids have been produced from oral stem cells: they appear as neurosphere-like structures diffusely expressing the neural marker β-III tubulin and containing NM-like granules. Our findings open up a novel and fascinating opportunity to rethink oral stem cells, and the derived 3D disease models, as a strategic and reliable tool for unveiling the neurodegenerative alterations.

Periodontitis (PD) is a common inflammatory disease known to be closely associated with metabolic disorders, particularly hyperlipidemia. In the current study, we demonstrated that hypercholesterolemia is a predisposing factor in the development of PD. Logistic regression analysis revealed a strong positive correlation between PD and dyslipidemia. Data from in vivo (PD mouse model subjected to a high cholesterol diet) and in vitro (cholesterol treatment of gingival fibroblasts [GFs]) experiments showed that excess cholesterol influx into GFs potentially contributes to periodontal inflammation and, subsequently, alveolar bone erosion. Additionally, we compared the protective efficacies of cholesterol-lowering drugs with their different modes of action against PD pathogenesis in mice. Among the cholesterol-lowering drugs we tested, fenofibrate exerted the most protective effect against PD pathogenesis due to an increased level of high-density lipoprotein cholesterol, a lipoprotein involved in cholesterol efflux from cells and reverse cholesterol transport. Indeed, cholesterol efflux was suppressed during PD progression by downregulation of the apoA-I binding protein (APOA1BP) expression in inflamed GFs. We also demonstrated that the overexpression of APOA1BP efficiently regulated periodontal inflammation and the subsequent alveolar bone loss by inducing cholesterol efflux. Our collective findings highlight the potential utility of currently available cholesterol-lowering medications for the mitigation of PD pathogenesis. By targeting the acceleration of high-density lipoprotein-mediated cellular cholesterol efflux, a new therapeutic approach for PD may become possible.

Human adipose-derived stem cells (hASCs) are commonly used in bone tissue regeneration. The N6-methyladenosine (m⁶A) modification has emerged as a novel regulatory mechanism for gene expression, playing a critical role in osteogenic differentiation of stem cells. However, the precise role and mechanism of alkylation repair homolog 5 (ALKBH5) in hASC osteogenesis remain incompletely elucidated and warrant further investigation. Herein, we employed methylated RNA immunoprecipitation sequencing, RNA sequencing, and weighted gene coexpression network analysis to identify a key long noncoding RNA (lncRNA) in hASCs: lncRNA AK311120. Functional experiments demonstrated that lnc-AK311120 promoted the osteogenic differentiation of hASCs, while a mutation at the m⁶A central site A of lnc-AK311120 was found to decrease the level of m⁶A modification. The osteogenic effect of ALKBH5 was confirmed both in vitro and in vivo using a mandibular defect model in nude mice. Subsequent investigations revealed that knockdown of ALKBH5 resulted in a significant increase in the m⁶A modification level of lnc-AK311120, accompanied by a downregulation in the expression level of lnc-AK311120. Additional rescue experiments demonstrated that overexpression of lnc-AK311120 could restore the phenotype after ALKBH5 knockdown. We observed that AK311120 interacted with the RNA-binding proteins DExH-Box helicase 9 (DHX9) and YTH domain containing 2 (YTHDC2) to form a ternary complex, while mitogen-activated protein kinase kinase 7 (MAP2K7) served as the shared downstream target gene of DHX9 and YTHDC2. Knockdown of AK311120 led to a reduction in the binding affinity between DHX9/YTHDC2 and the target gene MAP2K7. Furthermore, ALKBH5 facilitated the translation of MAP2K7 and activated the downstream JNK signaling pathway through the AK311120–DHX9–YTHDC2 complex, without affecting its messenger RNA level. Collectively, we have investigated the regulatory effect and mechanism of ALKBH5-mediated demethylation of lncRNA in hASC osteogenesis for the first time, offering a promising approach for bone tissue engineering.

N6,2′-O-dimethyladenosine (m⁶Am), a common mRNA modification in eukaryotic capped mRNAs, plays a pivotal role in cellular functions and disease progression. However, its involvement in host inflammation remains elusive. Here, we demonstrate that loss of m⁶Am methyltransferase phosphorylated CTD interacting factor 1 (PCIF1) attenuates periodontal inflammation in whole-body and myeloid lineage–specific knockout mouse models. Pcif1 deletion inhibits macrophage phagocytosis and migration through m⁶Am-Csf1r signaling. In addition, colony-stimulating factor-1 receptor (CSF1R) is identified as a potential target for the treatment of periodontitis. We thus reveal a previously unrecognized role for PCIF1-mediated m⁶Am modification in governing macrophage responses and periodontal inflammation.

Mesenchymal stromal cells (MSCs) are multipotent, progenitor cells that reside in tissues across the human body, including the periodontal ligament (PDL) and gingiva. They are a promising therapeutic tool for various degenerative and inflammatory diseases. However, different heterogeneity levels caused by tissue-to-tissue and donor-to-donor variability, and even intercellular differences within a given MSCs population, restrict their therapeutic potential. There are considerable efforts to decipher these heterogeneity levels using different “omics” approaches, including single-cell transcriptomics. Previous studies applied this approach to compare MSCs isolated from various tissues of different individuals, but distinguishing between donor-to-donor and tissue-to-tissue variability is still challenging. In this study, MSCs were isolated from the PDL and gingiva of 5 periodontally healthy individuals and cultured in vitro. A total of 3,844 transcriptomes were generated using single-cell mRNA sequencing. Clustering across the 2 different tissues per donor identified PDL- and gingiva-specific and tissue-spanning MSCs subpopulations with unique upregulated gene sets. Gene/pathway enrichment and protein-protein interaction (PPI) network analysis revealed differences restricted to several cellular processes between tissue-specific subpopulations, indicating a limited tissue-of-origin variability in MSCs. Gene expression, pathway enrichment, and PPI network analysis across all donors’ PDL- or gingiva-specific subpopulations showed significant but limited donor-to-donor differences. In conclusion, this study demonstrates tissue- and donor-specific variabilities in the transcriptome level of PDL- and gingiva-derived MSCs, which seem restricted to specific cellular processes. Identifying tissue-specific and tissue-spanning subpopulations highlights the intercellular differences in dental tissue–derived MSCs. It could be reasonable to control MSCs at a single-cell level to ensure their properties before transplantation.