METTL3-Mediated m6A Modification Regulates the Osteogenic Differentiation through LncRNA CUTALP in Periodontal Mesenchymal Stem Cells of Periodontitis Patients.

Objective: Periodontitis is a chronic inflammatory disease that causes loss of periodontal support tissue. Our objective was to investigate the mechanism by which METTL3-mediated N6-methyladenosine modification regulates the osteogenic differentiation through lncRNA in periodontal mesenchymal stem cells in patients with periodontitis (pPDLSCs). Material and Methods. We carried out a series of experiments, including methylated RNA immunoprecipitation-PCR, quantitative real-time polymerase chain reaction, and western blotting. The expressions of alkaline phosphatase (ALP), Runx2, Col1, Runx2 protein level, ALP staining, and Alizarin red staining were used to demonstrate the degree of osteogenic differentiation. Results: We found that METTL3 was the most significantly differentially expressed methylation-related enzyme in pPDLSCs and promoted osteogenic differentiation of pPDLSCs. METTL3 regulated the stability and expression of lncRNA CUTALP, while lncRNA CUTALP promoted osteogenic differentiation of pPDLSCs by inhibiting miR-30b-3p. At different time points of osteogenic differentiation, lncRNA CUTALP expression was positively correlated with Runx2, while miR-30b-3p showed the opposite pattern. The attenuated osteogenic differentiation induced by METTL3 knockdown was recovered by lncRNA CUTALP overexpression. The attenuated osteogenic differentiation induced by lncRNA CUTALP knockdown could be reversed by the miR-30b-3p inhibitor. Conclusions: In summary, METTL3/lncRNA CUTALP/miR-30b-3p/Runx2 is a regulatory network in the osteogenic differentiation of pPDLSCs.

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis.

Introduction: Open gingival embrasure (OGE) is a common complication in adults following clear aligner therapy and the influence of gingival or alveolar bone biotype on OGE is of great concern. Unfortunately, due to the limited number of patients with clearaligner therapy and the clinical methods to distinguish the gingival biotype of patients being invasive, it is difficult to carry out clinical studies on the gingival or alveolar bone biotype of the OGE. In the meanwhile, the detailed biomechanics of the occurrence of OGE remains unknown. The goal of this study was to establish a new model to simulate the virtual space region, namely, the OGE region, to investigate the relationship between alveolar bone biotype and the occurrence of OGE, and explore potential biomechanical factors related to OGE. Methods: The OGE region in the interproximal space was established using a filler with a very low modulus of elasticity (1 × 10-6 MPa). To illustrate the biomechanics of OGE more exhaustively, a line was created at the top of the alveolar crest along the proximal tooth root. FEA was then used to analyze the biomechanics of the surrounding tissues, the OGE region and the line at the top of the alveolar crest along the proximal tooth root of the central incisor under two different labial bone thicknesses (thick and thin) with an axial inclination of 80°, 90° and 100°. Results: During intrusion of the incisors in clear aligner therapy, as inclination increased or bone tissue became thinner, the stress in the surrounding tissues [tooth root, alveolar crest, and periodontal ligament (PDL)] was greater. In the OGE region and interproximal alveolar crest, the strain increased with increasing inclination and labial bone thinning. The results from the line at the top of the alveolar crest along the proximal tooth root showed more detailed biomechanics: In all groups, stress and strain were focused on the mesial-labial alveolar crest. Interestingly, our results also demonstrated that when OGE occurs, other complications may arise, including root resorption and bone dehiscence.

Microbiome and metabolome associated with white spot lesions in patients treated with clear aligners.

White spot lesions (WSLs) have long been a noteworthy complication during orthodontic treatment. Recently, an increasing number of orthodontists have found that adolescents undergoing orthodontic treatment with clear aligners are at a higher risk of developing WSLs. The oral microbiota and metabolites are considered the etiologic and regulatory factors of WSLs, but the specific impact of clear aligners on the oral microbiota and metabolites is unknown. This study investigated the differences in the salivary microbiome and metabolome between adolescents with and without WSLs treated with clear aligners. Fifty-five adolescents (aged 11-18) with Invisalign appliances, 27 with and 28 without WSLs, were included. Saliva samples were analyzed using 16S rRNA gene sequencing and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS); the data were further integrated for Spearman correlation analysis. The relative abundances of 14 taxa, including Actinobacteria, Actinomycetales, Rothia, Micrococcaceae, Subdoligranulum, Capnocytophaga, Azospira, Olsenella, Lachnoanaerobaculum, and Abiotrophia, were significantly higher in the WSL group than in the control group. Metabolomic analysis identified 27 potential biomarkers, and most were amino acids, including proline and glycine. The metabolites were implicated in 6 metabolic pathways, including alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism; and aminoacyl-tRNA biosynthesis. There was a correlation between the salivary microbial and metabolomic datasets, reflecting the impact of clear aligners on the metabolic activity of the oral flora. A concordant increase in the levels of Lachnoanaerobaculum, Rothia, Subdoligranulum and some amino acids had predictive value for WSL development. In summary, when adolescents undergo long-term clear aligner therapy with poor oral hygiene habits, clear aligners can disrupt the balance of the oral microecosystem and lead to oral microbiota dysbiosis, thereby increasing the risk of developing WSLs. Our findings might contribute to the understanding of the pathogenesis of WSLs and provide candidate biomarkers for the diagnosis and treatment of WSLs associated with clear aligners.

Effects of upper-molar distalization using clear aligners in combination with Class II elastics: a three-dimensional finite element analysis.

INTRODUCTION: The effects of upper-molar distalization using clear aligners in combination with Class II elastics for anchorage reinforcement have not been fully investigated yet. The objective of this study is to analyze the movement and stress of the whole dentition and further explore guidelines for the selection of traction methods. METHODS: Three-dimensional (3D) finite element models are established to simulate the sequential molar distalization process, including the initial distalization of the 2nd molar (Set I) and the initial distalization of the 1st molar (Set II). Each group set features three models: a control model without Class II elastics (model A), Class II elastics attached to the tooth by buttons (model B), and Class II elastics attached to the aligner by precision cutting (model C). The 3D displacements, proclination angles, periodontal ligament (PDL) hydrostatic stress and alveolar bone von Mises stress in the anterior area are recorded. RESULTS: In all of the models, the maxillary anterior teeth are labial and mesial proclined, whereas the distal moving molars exhibit distal buccal inclination with an extrusion tendency. With the combination of Class II elastics, the anchorage was effectively reinforced; model C demonstrates superior anchorage reinforcement with lower stress distribution in comparison with model B. The upper canines in model B present an extrusion tendency. Meanwhile, the mandibular dentition in models B and C experience undesired movement tendencies with little discrepancy from each other. CONCLUSIONS: Class II elastics are generally effective for anchorage reinforcement as the upper-molar distalization is performed with clear aligners. Class II elastics attached to an aligner by precision cutting is a superior alternative for maxillary anchorage control in cases that the proclination of upper incisors and extrusion of upper canines are unwanted.

CXCL8, MMP12, and MMP13 are common biomarkers of periodontitis and oral squamous cell carcinoma.

OBJECTIVE: To analysis the relationship between periodontitis (PD) and oral squamous cell carcinoma (OSCC) by bioinformatic analysis. MATERIALS AND METHODS: We analyzed the gene expression profiles of PD (GSE16134) from the Gene Expression Omnibus (GEO) database and OSCC samples from TCGA-HNSC (head and neck squamous cell carcinoma) and identified common differentially expressed genes (DEGs) in PD and OSCC. Then, functional annotation and signaling pathway enrichment, protein interaction network construction, and hub gene identification were performed. Subsequently, the function and signaling pathway enrichment of hub genes, miRNA interaction, and transcription factor interaction analyses were carried out. We analyzed GSE10334 and GSE30784 as validation datasets, and performed qRT-PCR experiments simultaneously for validation, and obtained 4 hub genes. Finally, immune infiltration analysis and clinical correlation analysis of 4 hub genes and related miRNAs were performed. RESULTS: We identified 31 DEGs (16 up-regulated and 15 down-regulated). Four hub genes were obtained by qRT-PCR and validation dataset analysis, including IL-1ß, CXCL8, MMP12, and MMP13. The expression levels of them were all significantly upregulated in both diseases. The functions of these genes focus on three areas: neutrophil chemotaxis, migration, and CXCR chemokine receptor binding. Key pathways include IL-17 signaling pathway, chemokine signaling pathway, and cytokine-cytokine receptor interactions pathway. Immune infiltration analysis showed that the expressions of 4 hub genes were closely related to a variety of immune cells. ROC curve analysis indicated that AUCs of 4 hub genes are all greater than 0.7, among which MMP12 and MMP13 were greater than 0.9. Kaplan-Meier survival analysis indicated that worse OS was strongly correlated with CXCL8 and MMP13 high-expression groups. MMP12 low-expression group was strongly associated with worse OS. The results of multivariate Cox regression analysis showed that age, N stage, CXCL8, MMP12, and MMP13 were independent prognostic factors for OS. We also identified 3 miRNAs, including hsa-miR-19b-3p, hsa-miR-181b-2-3p, and hsa-miR-495-3p, that were closely related to 4 hub genes. Hsa-miR-495-3p is closely related to the diagnosis and prognosis of OSCC. CONCLUSIONS: We identified 4 hub genes between PD and OSCC, including IL-1ß, CXCL8, MMP12, and MMP13. These genes may mediate the co-morbid process of PD and OSCC through inflammation-related pathways such as the IL-17 signaling pathway. It is worth noting that CXCL8, MMP12, and MMP13 have great significance in the diagnosis and prognosis of OSCC.

The three-dimensional displacement tendency of teeth depending on incisor torque compensation with clear aligners of different thicknesses in cases of extraction: a finite element study.

BACKGROUND: Despite the popularity of clear aligner treatment, the effect of the thickness of these aligners has not been fully investigated. The objective of this study was to assess the effects of incisor torque compensation with different thicknesses of clear aligner on the three-dimensional displacement tendency of teeth in cases of extraction. METHODS: Three-dimensional finite element models of the maxillary dentition with extracted first premolars, maxilla, periodontal ligaments, attachments, and aligners were constructed and subject to Finite Element Analysis (FEA). Two groups of models were created: (1) with 0.75 mm-thick aligners and (2) with 0.5 mm-thick aligners. A loading method was developed to simulate the action of clear aligners for the en masse retraction of the incisors. Power ridges of different heights were applied to both groups to mimic torque control, and the power ridges favoring the translation of the central incisors were selected. Then, we used ANSYS software to analyze the initial displacement of teeth and the principle stress on the PDL. RESULTS: Distal tipping, lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, and mesial tipping and intrusion of the posterior teeth were all generated by clear aligner therapy. With the 0.5 mm-thick aligner, a power ridge of 0.7 mm could cause bodily retraction of the central incisors. With the 0.75 mm-thick aligner, a power ridge of 0.25 mm could cause translation of the central incisors. Aligner torque compensation created by the power ridges generated palatal root torque and intrusion of the incisors, intrusion of the canines, mesial tipping and the intrusion of the second premolar; these effects were more significant with a 0.75 mm-thick aligner. After torque compensation, the stress placed on the periodontal ligament of the incisors was distributed more evenly with the 0.75 mm-thick aligner. CONCLUSIONS: The torque compensation caused by power ridges can achieve incisor intrusion and palatal root torque. Appropriate torque compensation with thicker aligners should be designed to ensure bodily retraction of anterior teeth and minimize root resorption, although more attention should be paid to the anchorage control of posterior teeth in cases of extraction.

Torque movement of the upper anterior teeth using a clear aligner in cases of extraction: a finite element study.

BACKGROUND: Clear aligner treatment has become popular over recent years. It is necessary to identify methods by which we could avoid the bowing effect in extractions with clear aligner. The present study was to identify the appropriate method to design torque movement involving the upper anterior teeth of extraction cases, in order to maintain or improve the axis and torque of the upper anterior teeth with a clear aligner during movement and closure of the extraction space. RESULTS: As the height of the power ridge increased, the rotation angle of the upper central incisor in the sagittal direction decreased gradually and the location of the rotation center changed significantly; the rotation center moved in the apical direction and then changed to the crown side. The highest von-Mises stress of the upper central incisor root, periodontal ligaments, and alveolar bone, showed little change as the power ridge height increased. When the axial inclination of the upper central incisor was normal (U1-SN = 105°), the tendency of movement for the upper central incisor approached translation with a power ridge height of 0.7 mm (corresponding distorted angle: 5.8415). When the axial inclination of the upper central incisor was oversized (U1-SN = 110°), the axial inclination of the upper central incisor reduced to normal following completion of the anterior segment retraction with a power ridge of 0.4 mm (corresponding distorted angle: 3.4265). CONCLUSION: Analysis indicates that pure palatal tipping movement of the upper anterior teeth is generated without torque control, thus resulting in the bowing effect. The required torque control of the upper anterior teeth with oversize axial inclination is weaker than that of the upper anterior teeth with normal axial inclination because limited torque loss is expected for oversize axial inclination teeth. Variation sensitivity of the rotation center should be considered carefully due to biological problems when designing translation of the upper anterior teeth with normal axial inclination.

[Effects of different crystalloid resuscitation on renal function in septic shock rabbits under the guidance of pulse indicator continuous cardiac output].

OBJECTIVE: To study the effect of different crystalloid resuscitation on renal function in septic shock rabbits, and to provide a theoretical basis for the choice of crystalloid for clinical fluid resuscitation. METHODS: Thirty-six healthy male New Zealand white rabbits were divided into six groups by random number table: control group, model group, and four crystalloid groups including normal saline (NS) group, lactate Ringer solution (LR) group, acetate Ringer solution (AR) group, and sodium potassium magnesium calcium glucose injection (SPMCG) group, with 6 rabbits in each group. Rabbits were infused with Escherichia coli lipopolysaccharide (LPS) 500 µg/kg via the marginal ear vein (infused at a constant speed within 20 minutes), and then continued to infuse in an increase of 300 µg/kg every 10 minutes, the maximum dose was 2 mg/kg, until the mean arterial pressure (MAP) dropped to 60% of the basal value, the septic shock model was considered to be successfully reproduced. The rabbits in the control group were not injected with LPS, and other operations were the same as in the model group. Different crystalloid groups were given crystal solution immediately after modeling for resuscitation (predetermined fluid volume 60 mL/kg, transfusion within 3 hours). The volume stress test was performed every hour to guide the fluid volume, and the stroke volume index increase rate (ΔSVI) < 15% was the end point of resuscitation. The control group and the model group were given NS 4 mL×kg-1×h-1 to maintain the physiological requirement. All groups were given tracheotomy and mechanical ventilation, and the hemodynamic changes were monitored by pulse-indicated continuous cardiac output (PiCCO). The dynamic changes of hemodynamic indexes, arterial blood gas analysis, electrolytes, blood glucose and renal function biomarkers were monitored before modeling, immediately after modeling and 3, 6, and 12 hours after resuscitation. RESULTS: (1) Hemodynamic indicators: after modeling, the MAP in the model group and the four fluid resuscitation groups decreased significantly, the cardiac index (CI) increased, and the systemic vascular resistance index (SVRI), global end-diastolic volumn index (GEDVI) decreased. After different crystalloid resuscitation at different time points, MAP, SVRI, and GEDVI increased in the four crystalloid groups. (2) Arterial blood gas analysis, electrolytes, blood glucose: blood lactic acid (Lac) in the model group and the four fluid resuscitation groups increased after model success. After fluid resuscitation, the Lac of each crystalloid group began to decrease and reached to the lowest at 12 hours. Compared with the LR, AR and SPMCG groups, the pH value decreased in the NS group at 6 hours and 12 hours of fluid resuscitation (6 hours: 7.29±0.00 vs. 7.40±0.02, 7.35±0.02, 7.37±0.02; 12 hours: 7.27±0.02 vs. 7.38±0.02, 7.39±0.02, 7.35±0.01; all P < 0.05). After fluid resuscitation, blood Cl- levels at 3, 6, and 12 hours in the NS group were significantly higher than those in the LR, AR and SPMCG groups (mmol/L: 113.4±0.6 vs. 101.4±3.6, 108.0±1.1, 106.0±0.8 at 3 hours; 115.1±2.0 vs. 101.1±2.7, 109.0±2.2, 105.3±0.6 at 6 hours; 116.9±0.1 vs. 104.2±4.4, 107.6±1.7, 108.7±0.6 at 12 hours; all P < 0.05). There was no significant difference in blood glucose at each time point among the four crystalloid groups. (3) Biomarkers of renal function: blood and urine neutrophil gelatinase associated lipocalin (NGAL) and cystatin C (Cys C) were significantly increased in the model group and four fluid resuscitation groups. After fluid resuscitation, blood, urine NGAL and Cys C decreased. There was no significant difference in blood, urine NGAL and Cys C at all the time points among the different fluid resuscitation groups. CONCLUSIONS: In the rabbit model of septic shock induced by Escherichia coli LPS, hyperchloremia and acidosis occurred after NS resucitation, but did not occur during the recovery of LR, AR and SPMCG. There was no difference in the effects of different crystalloid resuscitation on renal function in septic shock rabbits.

Comparison of interleukin expression in gingival crevicular fluid between patients with invisible orthodontics treat-ment and fixed orthodontics treatment.

OBJECTIVES: To compare the expression levels of interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-16, and IL-18 in gingival crevicular fluid between patients with invisible orthodontics treatment and fixed orthodontics treatment. METHODS: A total of 67 patients with invisible orthodontic treatment were selected as the observation group, and 40 patients with fixed orthodontic treatment were selected as the control group. The expression levels of IL-1ß, IL-6, IL-8, IL-10, IL-16, and IL-18 in gingival crevicular fluid before, 24 h, and 12 months after orthodontic treatment were detected. RESULTS: No significant difference in basic characteristics and interleukin expression levels in gingival crevicular fluid was observed between the two groups before orthodontic treatment (P>0.05). After 24 h of orthodontic treatment, the expression levels of IL-1ß, IL-6, IL-8, IL-10, and IL-18 in gingival crevicular fluid increased in both groups; however, no significant difference was observed between the two groups (P>0.05). After 12 months of orthodontic treatment, the expression levels of IL-1ß, IL-6, IL-8, IL-10, and IL-18 in gingival crevicular fluid in the observation group were significantly lower than those in the control group (P<0.05), and no significant difference in the expression level of IL-16 was observed between the two groups (P>0.05). CONCLUSIONS: Compared with patients with fixed orthodontics treatment, those with invisible orthodontics treatment had weaker oral inflammatory response, which was conducive to the recovery of the oral microenvironment.