Comparison of invisalign mandibular advancement and twin-block on upper airway and hyoid bone position improvements for skeletal class II children: a retrospective study.

BACKGROUND: This study is to evaluate and compare the improvement of upper airway morphology and hyoid bone position in children with Class II mandibular retrusion treated with Invisalign mandibular advancement (MA) and Twin-Block (TB) appliances, utilizing cone beam computed tomography (CBCT). METHODS: 32 children aged between 8 and 11.5 years old were included in this study, with an average age of 10.2 years old. These children were divided into two groups, MA and TB, with 16 children in each group. Changes in upper airway morphology and hyoid bone position before and after treatment were analyzed using CBCT. RESULTS: (1) Changes in upper airway before and after treatment: the oropharynx volume (Or-V), the oropharynx minimum cross-sectional area (Or-mCSA), the hypopharynx volume (Hy-V), and the hypopharynx minimum cross-sectional area (Hy-mCSA) in both the MA and TB groups increased after treatment, and the differences were statistically significant (P < 0.05) compared to pre-treatment status. (2) Changes in hyoid bone position before and after treatment: The distances between H point and third cervical vertebra (H-C3), H point and pogonion (H-RGN), H point and mandibular plane (H-MP), H point and Frankfort horizontal plane (H-FH), H and S point (H-S), and H point and palatal plane (H-PP) in both the MA and TB groups increased after treatment, and the differences were statistically significant (P < 0.05). CONCLUSION: Both MA and TB appliances effectively improved the structural narrowness of the upper airway and reduced respiratory resistance, thus improving breath quality. However, MA showed more effectiveness in improving the narrowest part of the hypopharynx compared to TB. Both appliances also promoted anterior downward movement of the hyoid bone, which opens the upper airway of the oropharynx and hypopharynx and helps the upper airway morphology return to normal range.

Comprehensive analysis of M2 macrophage-derived exosomes facilitating osteogenic differentiation of human periodontal ligament stem cells.

BACKGROUND: The role of periodontal ligament stem cells (PDLSCs) and macrophage polarization in periodontal tissue regeneration and bone remodeling during orthodontic tooth movement (OTM) has been well documented. Nevertheless, the interactions between macrophages and PDLSCs in OTM remain to be investigated. Consequently, the present study was proposed to explore the effect of different polarization states of macrophages on the osteogenic differentiation of PDLSCs. METHODS: After M0, M1 and M2 macrophage-derived exosomes (M0-exo, M1-exo and M2-exo) treatment of primary cultured human PDLSCs, respectively, mineralized nodules were observed by Alizarin red S staining, and the expression of ALP and OCN mRNA and protein were detected by RT-qPCR and Western blotting, correspondingly. Identification of differentially expressed microRNAs (DE-miRNA) in M0-exo and M2-exo by miRNA microarray, and GO and KEGG enrichment analysis of DE-miRNA targets, and construction of protein-protein interaction networks. RESULTS: M2-exo augmented mineralized nodule formation and upregulated ALP and OCN expression in PDLSCs, while M0-exo had no significant effect. Compared to M0-exo, a total of 52 DE-miRNAs were identified in M2-exo. The expression of hsa-miR-6507-3p, hsa-miR-4731-3p, hsa-miR-4728-3p, hsa-miR-3614-5p and hsa-miR-6785-3p was significantly down-regulated, and the expression of hsa-miR-6085, hsa-miR-4800-5p, hsa-miR-4778-5p, hsa-miR-6780b-5p and hsa-miR-1227-5p was significantly up-regulated in M2-exo compared to M0-exo. GO and KEGG enrichment analysis revealed that the downstream targets of DE-miRNAs were mainly involved in the differentiation and migration of multiple cells. CONCLUSIONS: In summary, we have indicated for the first time that M2-exo can promote osteogenic differentiation of human PDLSCs, and have revealed the functions and pathways involved in the DE-miRNAs of M0-exo and M2-exo and their downstream targets.

Comparison of Anchorage Efficiency of Orthodontic Mini-implant and Conventional Anchorage Reinforcement in Patients Requiring Maximum Orthodontic Anchorage: A Systematic Review and Meta-analysis.

OBJECTIVE: To compare the clinical effectiveness of mini-implants (MIs) and conventional anchorage appliances used for orthodontic anchorage reinforcement in patients with class I or II malocclusion with bimaxillary protrusion. MATERIALS AND METHODS: Literature search was conducted through PubMed, Embase, and Cochrane from inception to July 2018. The following Medical Subject Heading terms were used for the search string: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Standardized mean difference (SMD) and 95% confidence interval (CI) of horizontal and vertical movements of teeth from baseline were used for comparison. RESULTS: A total of 12 studies were included in the final analysis. MI group significantly lowered mesial movement of molars compared to conventional anchorage group (SMD = -1.48, 95% CI = -2.25 to -0.72; P = .0002). There was significantly higher retraction of incisors in the MI group than in the conventional group (SMD = -0.47 mm, 95% CI = -0.87 to -0.07; P = .02). No significant difference was seen in vertical movement of molars (SMD = -0.21 mm, 95% CI = -0.87 to 0.45; P = .52) and incisors (SMD = -0.30, 95% CI = -1.18 to 0.58; P = .5). CONCLUSION: MIs seem to be more effective than the conventional anchorage devices in terms of minimizing unintended mesial movement of molars with maximum retraction of anterior teeth.

Orthodontic compressive force modulates Ets-1/Tks5 pathway to promote the formation of circumferential invadopodia and the fusion of osteoclast precursors.

During orthodontic treatment a mechanical force is applied to the teeth. However, it remains unclear how mechanical force promotes the maturation and fusion of osteoclast precursors into osteoclasts. In this study, we aimed to explore the mechanism by which orthodontic compressive force promotes osteoclast maturation. We used a RAW264.7 macrophage-like cell line derived from Balb/c mice as the experimental model. We found that compressive force promoted the maturation of osteoclasts based on tartrate-resistant acid phosphatase staining and the formation of invadopodia based on immunstaining of Tks5 and F-actin. Moreover, we found that compressive force upregulated the expression of Ets-1 and Tks5 and promoted the activation of Ets-1 in RAW264.7 cells. Furthermore, we identified Tks5 as a transcription target of Ets-1 in RAW264.7 cells and demonstrated that Ets-1 mediates the effects of compressive force on Tks5 upregulation, invadopodia formation and cell fusion in osteoclasts. In conclusion, Ets-1 is upregulated by compressive force and it is essential to transducing the mechanical signal to promote invadopodia formation and osteoclast fusion. Our findings provide novel insight into the mechanism underlying osteoclast maturation and fusion during orthodontic treatment.

Soft Tissue Changes in Patients With Dentoalveolar Protrusion Treated With Maximum Anchorage: A Systematic Review and Meta-analysis.

OBJECTIVE: This meta-analysis aimed at comparing the angular and linear changes of soft tissue profile using conventional anchorage techniques and mini-implant (MI)-based space closure in patients with dentoalveolar protrusion. MATERIALS AND METHODS: Electronic databases, viz. PubMed, Embase, and Cochrane Central Register of Controlled Trials, were searched for relevant literature from their inception to December 2017 according to the specific inclusion and exclusion criteria. The following Medical Subject Heading terms were used for searching: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Selected randomized control trials (RCTs) were assessed for their quality using Cochrane's Risk of Bias Tool, whereas the Newcastle-Ottawa scale was used for non-RCTs. Standardized mean difference (SMD) and 95% confidence interval (CI) were obtained with either fixed- or random-effects models based on the heterogeneity of the included studies. RESULTS: A total of 5 articles (2 RCTs with moderate risk of bias and 3 high-quality non-RCT studies) were included in the final analysis. The nasolabial angle had significantly greater changes in the MI group than in the conventional anchorage group (SMD = 0.68, 95% CI = 0.39 to 0.97, P < .0001). Significantly higher retraction of the upper lip was seen in the MI group than in the conventional group (SMD = -0.51, 95% CI = -0.84 to -0.18; P = .002). No significant difference was seen in the facial convexity (SMD = -0.34, 95% CI = -0.76 to 0.07, P = .106) and lower lip retraction (SMD = 0.28, 95% CI = -1.72 to 2.28, P = .784) between the groups. CONCLUSION: It was seen that MIs facilitated favorable soft tissue profile than the conventional anchorage devices. However, more high-quality studies are warranted to confirm the clinical effectiveness of MIs.

The effect of cyclic tensile force on the actin cytoskeleton organization and morphology of human periodontal ligament cells.

To explore Girdin/Akt pathway protein expression and morphology change by cyclic tension in the periodontal ligament cells. Human periodontal ligament cells were exposed to cyclic tension force at 4000 µstrain and 0.5 Hz for 6 h though a four-point bending system. Cyclic tension force upregulated F-actin, Girdin and Akt expression in hPDL. In transmission electron microscope assay showed that there are more and bigger mitochondria, more and longer cynapses, more cellular organisms after tension force stimulation than control. The actin filament was changed to be regular lines and pointed to poles of cells. However, we found that the Girdin-depleted cells are small and there are more micro-organisms including more lysosomes and matrix vesicles than control. These finding suggest that the STAT3/Girdin/Akt pathway in PDL to response to mechanical stimulation as well, and Girdin may play a significant role in triggering cell proliferation and migration during orthodontic treatment. It provided an insight into the molecular basis for development of a vitro cell model in studying orthodontic treatment.

Girdin/GIV is upregulated by cyclic tension, propagates mechanical signal transduction, and is required for the cellular proliferation and migration of MG-63 cells.

To explore how Girdin/GIV is regulated by cyclic tension and propagates downstream signals to affect cell proliferation and migration. Human osteoblast-like MG-63 cells were exposed to cyclic tension force at 4000 µstrain and 0.5 Hz for 6 h, produced by a four-point bending system. Cyclic tension force upregulated Girdin and Akt expression and phosphorylation in cultured MG-63 cells. Girdin and Akt each promoted the phosphorylation of the other under stimulated tension. In vitro MTT and transwell assays showed that Girdin and Akt are required for cell proliferation and migration during cellular quiescence. Moreover, STAT3 was determined to be essential for Girdin expression under stimulated tension force in the physiological condition, as well as for osteoblast proliferation and migration during quiescence. These findings suggest that the STAT3/Girdin/Akt pathway activates in osteoblasts in response to mechanical stimulation and may play a significant role in triggering osteoblast proliferation and migration during orthodontic treatment.

Small extracellular vesicles from dental follicle stem cells provide biochemical cues for periodontal tissue regeneration.

BACKGROUND: Treatments based on stem cell-derived small extracellular vesicles (sEVs) have been explored as an alternative to stem cell transplantation-based therapies in periodontal regeneration. Dental follicle stem cells (DFSCs) have shown great potential for regenerative medicine applications. However, it is unclear whether sEVs derived from DFSCs (DFSCs-sEVs) could be used in periodontal regeneration. This study investigates whether DFSCs-sEVs could regenerate damaged periodontal tissue and the potential underlying mechanism. METHODS: DFSCs-sEVs were isolated and identified, and periodontal ligament stem cells (PDLSCs) were cocultured with the isolated sEVs. The effect of DFSCs-sEVs on the biological behaviour of PDLSCs was examined using EdU assay, CCK-8 assay, cell cycle analysis, wound healing, alizarin red staining, qRT-PCR, and western blot analysis. RNA sequencing and functional enrichment analysis were used to detect the signal pathway involved in the effect of DFSCs-sEVs on PDLSCs. PDLSCs were pretreated with ERK1/2 or p38 MAPK inhibitors to investigate the possible involvement of the ERK1/2 and p38 MAPK pathways. Additionally, DFSCs-sEVs were combined with collagen sponges and transplanted into the periodontal defects in SD rats, and then, pathological changes in periodontal tissue were examined using haematoxylin and eosin (HE) staining and micro-CT. RESULTS: PDLSCs could internalize DFSCs-sEVs, thereby enhancing the proliferation assessed using EdU assay, CCK-8 assay and cell cycle analysis. DFSCs-sEVs significantly enhanced the migration of PDLSCs. DFSCs-sEVs promoted osteogenic differentiation of PDLSCs, showing deep Alizarin red staining, upregulated osteogenic genes (RUNX2, BSP, COL1), and upregulated protein expression (RUNX2, BSP, COL1, ALP). We found that p38 MAPK signalling was activated via phosphorylation. Inhibition of this signalling pathway with a specific inhibitor (SB202190) partially weakened the enhanced proliferation. After DFSCs-sEVs transplantation, new periodontal ligament-like structures and bone formation were observed in the damaged periodontal area in rats. Labelled DFSCs-sEVs were observed in the newly formed periodontal ligament and soft tissue of the defect area. CONCLUSIONS: Our study demonstrated that DFSCs-sEVs promoted periodontal tissue regeneration by promoting the proliferation, migration, and osteogenic differentiation of PDLSCs. The effect of DFSCs-sEVs in promoting PDLSCs proliferation may be partially attributed to the activation of p38 MAPK signalling pathway. DFSCs-sEVs provide us with a novel strategy for periodontal regeneration in the future.

External apical root resorption in orthodontic tooth movement: the risk factors and clinical suggestions from experts' consensus.

External apical root resorption is among the most common risks of orthodontic treatment, and it cannot be completely avoided and predicted. Risk factors causing orthodontic root resorption can generally be divided into patient- and treatment-related factors. Root resorption that occurs during orthodontic treatment is usually detected by radiographical examination. Mild or moderate root absorption usually does no obvious harm, but close attention is required. When severe root resorption occurs, it is generally recommended to suspend the treatment for 3 months for the cementum to be restored. To unify the risk factors of orthodontic root resorption and its clinical suggestions, we summarized the theoretical knowledge and clinical experience of more than 20 authoritative experts in orthodontics and related fields in China. After discussion and summarization, this consensus was made to provide reference for orthodontic clinical practice.