As the biological mechanisms of orthodontic tooth movement have been explored further, scholars have gradually focused on the remodelling mechanism of the extracellular matrix (ECM) in the periodontal ligament (PDL). The ECM of the PDL consists of various types of collagens and other glycoproteins. The specific process and mechanism of ECM remodelling during orthodontic tooth movement remains unclear. Collagen I and III, which constitute major components of the PDL, are upregulated under orthodontic force. The changes in the contents of ECM proteins also depend on the expression of ECM-related enzymes, which organise new collagen fibre networks to adapt to changes in tooth position. The matrix metalloproteinase family is the main enzyme that participates in collagen hydrolysis and renewal and changes its expression under orthodontic force. Moreover, ECM adhesion molecules, such as integrins, are also regulated by orthodontic force and participate in the dynamic reaction of cell adhesion and separation with the ECM. This article reviews the changes in ECM components, related enzymes and adhesion molecules in the PDL under orthodontic force to lay the foundation for the exploration of the regulatory mechanism of ECM remodelling during orthodontic tooth movement.

Radiographic examination has been an essential part of the diagnostic workflow in periodontology and implant dentistry. However, radiographic examination unavoidably involves ionizing radiation and its associated risks. Clinicians and researchers have invested considerable efforts in assessing the feasibility and capability of utilizing nonionizing imaging modalities to replace traditional radiographic imaging. Two such modalities have been extensively evaluated in clinical settings, namely, ultrasonography (USG) and magnetic resonance imaging (MRI). Another modality, optical coherence tomography (OCT), has been under investigation more recently. This review aims to provide an overview of the literature and summarize the usage of USG, MRI, and OCT in evaluating health and pathology of periodontal and peri-implant tissues. Clinical studies have shown that USG could accurately measure gingival height and crestal bone level, and classify furcation involvement. Due to physical constraints, USG may be more applicable to the buccal surfaces of the dentition even with an intra-oral probe. Clinical studies have also shown that MRI could visualize the degree of soft-tissue inflammation and osseous edema, the extent of bone loss at furcation involvement sites, and periodontal bone level. However, there was a lack of clinical studies on the evaluation of peri-implant tissues by MRI. Moreover, an MRI machine is very expensive, occupies much space, and requires more time than cone-beam computed tomography (CBCT) or intraoral radiographs to complete a scan. The feasibility of OCT to evaluate periodontal and peri-implant tissues remains to be elucidated, as there are only preclinical studies at the moment. A major shortcoming of OCT is that it may not reach the bottom of the periodontal pocket, particularly for inflammatory conditions, due to the absorption of near-infrared light by hemoglobin. Until future technological breakthroughs finally overcome the limitations of USG, MRI and OCT, the practical imaging modalities for routine diagnostics of periodontal and peri-implant tissues remain to be plain radiographs and CBCTs.

OBJECTIVE: The aim of the study is comparative analysis of the condition of oral organs and tissues in people with metabolic syndrome (MS) of varying severity before orthopedic dental rehabilitation based on dental implants.
METHODS: 255 patients (151 women and 104 men) aged from 35 to 65 years were examined. 3 groups were formed: 2 study groups and a comparison group. Groups 1 and 2 included individuals with excess body weight and MS. The control group consisted of 88 people without MS. An index assessment of the condition of the periodontium and tissue structures of the alveolar bone (according to cone-beam computed tomography), microcirculation in the gingival mucosa was carried out using laser Doppler flowmetry.
RESULTS: The analysis of the periodontal condition indicators showed that in all groups of patients with MS, periodontal pathology occurred, the value of which was significantly higher than in patients of the control group (p <0.05). The analysis of bone tissue according to CBCT data showed that the most favorable conditions (type 1 and type 2 of bone according to Misch) for dental implantation are found in people without MS, respectively 3.5% and 35.1% of cases. The intensity of blood flow (σ) was 21.2% lower in group 1 and 48% in group 2, compared with the control group. Vasomotor activity (Kv) was 13.2% lower in the first group and 35% lower in the second group. A decrease in amplitudes in the area of all rhythms in the LDF gram was found: low-frequency - by 15.6%, high-frequency - by 16.9%, pulse - by 3.6%.
CONCLUSIONS: Changes occurring in the organs and tissues of the mouth against the background of MS of varying severity lead to a decrease in tissue perfusion with blood and blood flow activity, a local decrease in bone density, and as a result, pathological changes in periodontal tissues. Before performing dental rehabilitation, it is necessary to take into account all the risks of possible complications caused by the general condition of organs and systems of people with MS.
UNASSIGNED: Сравнительный анализ состояния органов и тканей рта у лиц с метаболическим синдромом (МС) различной степени выраженности перед ортопедической стоматологической реабилитацией с опорой на дентальные имплантаты.
UNASSIGNED: Обследованы 255 пациентов (151 женщина и 104 мужчины) в возрасте от 35 до 65 лет. Сформировано 3 группы: 2 группы исследования и группа сравнения. В 1-ю и 2-ю группы вошли лица с избыточной массой тела и МС. Группу контроля составили 88 человек без МС. Проведена индексная оценка состояния пародонта и структур тканей альвеолярной кости (по данным конусно-лучевой компьютерной томографии), микроциркуляции в слизистой оболочке десны методом лазерной допплеровской флоуметрии.
UNASSIGNED: Установлено, что во всех группах пациентов с МС имелась патология пародонта, степень тяжести которой достоверно выше, чем у пациентов группы контроля (p<0,05). По данным конусно-лучевой компьютерной томографии (КЛКТ), наиболее благоприятными условиями (1-й и 2-й типы кости по классификации Misch) для проведения дентальной имплантации встречается у лиц без МС — соответственно 3,5 и 35,1% случаев. Интенсивность кровотока (σ) была ниже на 21,2% в 1-й группе и на 48% во 2-й группе по сравнению с таковой в контрольной группе. Вазомоторная активность (Kv) оказалась ниже на 13,2% в 1-й группе и на 35% во 2-й группе. Установлено снижение амплитуд в области всех ритмов в лазерной допплерограмме: низкочастотного — на 15,6%, высокочастотного — на 16,9%, пульсового — на 3,6%.
UNASSIGNED: Изменения, возникающие в органах и тканях рта на фоне МС разной степени выраженности, приводят к снижению активности кровотока и перфузии тканей, локальному снижению плотности кости и как следствие — к патологическим изменениям в тканях пародонта. Перед проведением стоматологической реабилитации необходимо учитывать все риски развития возможных осложнений, вызванных общим состоянием органов и систем пациентов с МС.

UNASSIGNED: This prospective study evaluated the effects of the metal-free crowns on the periodontal tissues of abutment teeth during a 12-month follow-up.
UNASSIGNED: A sample of 24 patients (N = 32 abutment teeth) who needed a single-tooth restoration were enrolled to receive either a metal-ceramic (n = 21) or lithium disilicate (n = 11). The single-unit crowns were evaluated at baseline, 3-and 12-month follow-up. The periodontal parameters were evaluated: plaque index (PI), gingival bleeding index (GBI), bleeding on probing (BOP), probing depth (PD), clinical attachment loss (CAL), radiographically and clinical crown fitting, bone resorption, and marginal finish lines. Statistical analyses were performed using the Exact Fisher and Mann-Whitney tests, and the Wilcoxon signed-rank test as a post hoc test for Friedman (95 % confidence interval).
UNASSIGNED: The marginal finish line showed a statistical difference with a biomaterial type (p =.004). After a 12-months, a significant increase was observed in PI and mean PD for abutment teeth of metal-ceramic crowns. The metal-free crowns presented higher values for GBI and CAL (p2 < 0.05). Only distal cervical evaluation and dental biofilm formation in the abutment teeth showed a statistical difference between the groups at the 12-month follow-up. The supragingival margin metal-ceramic group revealed higher PI values (p2 = 0.005) between the period and the subgingival margin of both biomaterials showed greater GBI scores (p2 < 0.05).
UNASSIGNED: Metal-free crowns showed better periodontal outcomes compared to metal-ceramic crowns. Single-unit crown marginal location affects the periodontal tissue condition of the abutment teeth. The marginal fit was not changed regarding the biomaterial type.

OBJECTIVE: The use of probiotics could promote the balance of the subgingival microbiota to contribute to periodontal health. This study aimed to identify the potential of bacteria commonly associated with healthy periodontal tissues as probiotic candidates.
METHODS: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the PubMed, Scopus, Science Direct, ProQuest, and Ovid databases as well as the combination of Medical Subject Headings (MeSH) and non-MeSH terms. Based on the selection criteria, original studies published in English and identifying the microorganisms present in the periodontium of healthy individuals and patients with periodontitis using the high-throughput 16S ribosomal gene sequencing technique were included.
RESULTS: Out of 659 articles, 12 met the criteria for this review. These articles were published from 2012 to 2020 and mainly originated from the United States, China, and Spain. Most of these studies reported adequate criteria for selecting participants, using standardized clinical criteria, and compliance with quality based on the tools used. In periodontal healthy tissue were identified species like Actinomyces viscosus, Actinomyces naeslundii, Haemophilus parainfluenzae, Rothia dentocariosa, Streptococcus sanguinis, Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus intermedius, and Prevotella nigrescens which have recognized strains with a capacity to inhibit periodontopathogens.
CONCLUSIONS: S. sanguinis, S. oralis, S. mitis, and S. gordonii are among the bacterial species proposed as potential probiotics because some strains can inhibit periodontopathogens and have been reported as safe for humans.

Periodontitis affects billions of people worldwide. To address relationships of periodontal niche cell types and microbes in periodontitis, we generated an integrated single-cell RNA sequencing (scRNAseq) atlas of human periodontium (34-sample, 105918-cell), including sulcular and junctional keratinocytes (SK/JKs). SK/JKs displayed altered differentiation states and were enriched for effector cytokines in periodontitis. Single-cell metagenomics revealed 37 bacterial species with cell-specific tropism. Fluorescence in situ hybridization detected intracellular 16 S and mRNA signals of multiple species and correlated with SK/JK proinflammatory phenotypes in situ. Cell-cell communication analysis predicted keratinocyte-specific innate and adaptive immune interactions. Highly multiplexed immunofluorescence (33-antibody) revealed peri-epithelial immune foci, with innate cells often spatially constrained around JKs. Spatial phenotyping revealed immunosuppressed JK-microniches and SK-localized tertiary lymphoid structures in periodontitis. Here, we demonstrate impacts on and predicted interactomics of SK and JK cells in health and periodontitis, which requires further investigation to support precision periodontal interventions in states of chronic inflammation.

OBJECTIVE: 10-methacryloyloxidecyl dihydrogen phosphate monomer (10-MDP) is commonly used as a bonding monomer in universal adhesives. Adhesives that contain this monomer can directly contact the surrounding periodontium due to the chemical binding of 10-MDP with hydroxyapatite in hard tissue to form calcium salts. However, the effect of these calcium salts on the periodontium in the case of subgingival fillings remains poorly understood. The objective of this study was to investigate effects of 10-MDP calcium salts on osteoblasts and fibroblasts in the periodontal tissues.
METHODS: This study investigated the effects of different concentrations of 10-MDP calcium salts on the migration, proliferation, and differentiation of osteoblasts (MC3T3-E1) and fibroblasts (L929); additionally, the effect on apoptosis and matrix metalloproteinases (MMPs) expression in these cells was evaluated. Cell proliferation assay, alkaline phosphatase (ALP) activity assay, Western blotting, and quantitative real-time polymerase chain reaction were performed to determine the effects.
RESULTS: The 10-MDP calcium salts (within a concentration of 0.5 mg/mL) showed no cytotoxicity and did not seem to influence the apoptosis, mitochondrial membrane potential, and reactive oxygen species (ROS) levels in the cells. However, they had an inhibitory effect on the secretion of MMP2 and MMP9 in the osteoblasts and fibroblasts. The ALP activity assay and Alizarin Red staining did not reveal any significant effects of the 10-MDP calcium salts on osteoblast differentiation.
CONCLUSIONS: These results suggest that applying 10-MDP-containing adhesives to subgingival fillings may be safe and beneficial for the periodontal tissues.

OBJECTIVE: This study examined how range concentrations of Fibroblast Growth Factor-2 (FGF-2) influence the differentiation and activity of human-derived periodontal ligament (hPDLSCs) and alveolar bone-derived stem cells (haBMSCs).
METHODS: hPDLSCs and haBMSCs were cultured with varying concentrations of FGF-2 (0, 1, 2.5, 5, 10, 20 ng/mL) and monitored for osteogenic differentiation through alkaline phosphatase (ALP) activity and quantification of gene expression (qRT-PCR) for osteogenesis markers. Additionally, alizarin red staining and a hydroxyproline colorimetric assay evaluated and quantified osteogenic matrix mineralization and collagen deposition. Statistical analyses were performed using one-way ANOVA or two-way ANOVA for multiple comparisons between groups.
RESULTS: At low FGF-2 concentrations, hPDLSCs differentiated toward an osteogenic lineage, whereas higher concentrations of FGF-2 inhibited osteogenesis and promoted fibroblastic differentiation. The effect of FGF-2 at the lowest concentration tested (1 ng/mL) led to significantly higher ALP activity than osteogenically induced positive controls at early time points and equivalent RUNX2 expression at early and later time points. FGF-2 supplementation of haBMSC cultures was sufficient, at all concentrations, to increase ALP activity at an earlier time point. Mineralization of haBMSC cultures increased significantly within 5-20 ng/mL FGF-2 concentrations under basal growth media conditions (α-minimal essential medium supplemented with 15 % fetal bovine serum and 1 % penicillin/streptomycin).
CONCLUSIONS: FGF-2 has a dual capacity in promoting osteogenic and fibroblastic differentiation within hPDLSCs contingent upon the dosage and timing of administration, alongside supporting osteogenic differentiation in haBMSCs. These findings underscore the need for precision growth factors dosing when considering the design of biomaterials for periodontal regeneration.

The regeneration of periodontal bone defects continues to be an essential therapeutic concern in dental biomaterials. Numerous biomaterials have been utilized in this sector so far. However, the immune response and vascularity in defect regions may be disregarded when evaluating the effectiveness of biomaterials for bone repair. Among several regenerative treatments, the most recent technique of in situ tissue engineering stands out for its ability to replicate endogenous restorative processes by combining scaffold with particular growth factors. Regenerative medicine solutions that combine biomaterials/scaffolds, cells, and bioactive substances have attracted significant interest, particularly for bone repair and regeneration. Dental stem cells (DSCs) share the same progenitor and immunomodulatory properties as other types of MSCs, and because they are easily isolable, they are regarded as desirable therapeutic agents in regenerative dentistry. Recent research has demonstrated that DSCs sown on newly designed synthetic bio-material scaffolds preserve their proliferative capacity while exhibiting increased differentiation and immuno-suppressive capabilities. As researchers discovered how short peptide sequences modify the adhesion and proliferative capacities of scaffolds by activating or inhibiting conventional osteogenic pathways, the scaffolds became more effective at priming MSCs. In this review, the many components of tissue engineering applied to bone engineering will be examined, and the impact of biomaterials on periodontal regeneration and bone cellular biology/molecular genetics will be addressed and updated.

Introduction: Prohibitin (PHB) is an essential scaffold protein that modulates signaling pathways controlling cell survival, metabolism, inflammation, and bone formation. However, its specific role in periodontium development remains less understood. This study aims to elucidate the expression pattern and function of PHB in periodontium development and its involvement in alveolar bone formation. Methods: Immunolocalization of PHB in the periodontium of postnatal (PN) mice were examined. Phb morpholino was micro-injected into the right-side mandible at PN5, corresponding to the position where the alveolar bone process forms in relation to the lower first molar. The micro-injection with a scramble control (PF-127) and the left-side mandibles were used as control groups. Five days post-micro-injection, immunohistochemical analysis and micro-CT evaluation were conducted to assess bone mass and morphological changes. Additionally, expression patterns of signaling molecules were examined following Phb downregulation using 24-h in vitro cultivation of developing dental mesenchyme at E14.5. Results: The immunostaining of PHB showed its localization in the periodontium at PN5, PN8, and PN10. The in vitro cultivation of dental mesenchyme resulted in alterations in Bmps, Runx2, and Wnt signalings after Phb knock-down. At 5 days post-micro-injection, Phb knocking down showed weak immunolocalizations of runt-related transcription factor (RUNX2) and osteocalcin (OCN). However, knocking down Phb led to histological alterations characterized by decreased bone mass and stronger localizations of Ki67 and PERIOSTIN in the periodontium compared 1 to control groups. The micro-CT evaluation showed decreased bone volume and increased PDL space in the Phb knock-down specimens, suggesting its regulatory role in bone formation. Discussion: The region-specific localization of PHB in the margin where alveolar bone forms suggests its involvement in alveolar bone formation and the differentiation of the periodontal ligament. Overall, our findings suggest that Phb plays a modulatory role in alveolar bone formation by harmoniously regulating bone-forming-related signaling molecules during periodontium development.