Comparative evaluation of transverse width indices for diagnosing maxillary transverse deficiency.

OBJECTIVES: This study aimed to compare and evaluate different transverse width indices for diagnosing maxillary transverse deficiency (MTD), a common malocclusion characterized by uncoordinated dental arches, crossbites, and tooth crowding. MATERIALS AND METHODS: Sixty patients aged 7-12 years were included in the study, with 20 patients diagnosed with MTD and 40 normal controls. Transverse width indices, including maxillary width at the buccal alveolar crest and lingual midroot level, as well as at the jugal process width, were measured. Differences between these indices and their corresponding mandibular indices were used as standardized transverse width indices. The reference range of these indices was determined and evaluated. Receiver operating characteristic (ROC) analysis was performed to evaluate their diagnostic ability. RESULTS: The transverse width indices and standardized transverse width indices of the MTD group were significantly smaller than those of the control group, except for the jugal process width. The evaluation of the reference range and ROC analysis revealed that the difference of the maxillomandibular width at buccal alveolar crest was the most accurate diagnostic method. CONCLUSIONS: The jugal point analysis method may not be suitable for diagnosing MTD. Instead, measuring the difference in maxillomandibular width at the buccal alveolar crest proves to be a more reliable and accurate diagnostic method for MTD.

AI model to detect contact relationship between maxillary sinus and posterior teeth.

Objectives: To establish a novel deep learning networks (MSF-MPTnet) based on panoramic radiographs (PRs) for automatic assessment of relationship between maxillary sinus floor (MSF) and maxillary posterior teeth (MPT), and to compare accuracy of MSF-MPTnet, dentists and radiologists identifying contact relationship. Study design: A total of 1035 PRs and 1035 Cone-beam computed tomographys （CBCT）images were collected from January 2018 to April 2022. The relationships were classified into class I and II by CBCT. Class I represents non-contact group, and class II represents contact group. 350 PRs were randomly selected as test dataset and accuracy of MSF-MPTnet, dentists, and radiologists was compared. Results: The intraclass correlation coefficient of dentists was 0.460-0.690 and it was 0.453-0.664 for radiologists. Sensitivity and accuracy of MSF-MPTnet were 0.682-0.852and 0.890-0.951, indicating that the output performance of MSF-MPTnet was reliable. Accuracy of maxillary premolars and molars were 79.7%-90.3 %, 76.2%-89.2 % and 72.9%-88.3 % in MSF-MPTnet model, dentists and radiologists. Accuracy of class I relationship in the MSF-MPTnet model (67.7%-94.6 %) was higher than that of dentists (56.5%-84.6 %) in maxillary first premolars and right second premolar, and accuracy of class I relationship in the MSF-MPTnet model is also higher than radiologists (40.0%-78.1 %) in all teeth positions (p < 0.05). Conclusions: MSF-MPTnet model could increase detecting accuracy of the relationship between MSF and MPT, minimize pseudo contact relationship and reduce frequency of CBCT use.

4D Printing of Personalized-Tunable Biomimetic Periosteum with Anisotropic Microstructure for Accelerated Vascularization and Bone Healing.

An ideal biomimetic periosteum is expected to wrap various bone surfaces to orchestrate an optimal microenvironment for bone regeneration, including facilitating local vascularization, recruiting osteoblasts, and mineralizing the extracellular matrix (ECM). To mimic the role of the natural periosteum in promoting bone repair, a 4D printing technique to inlay aligned cell sheets on shape-shifting hydrogel is used, containing biophysical signals and spatially adjustable physical properties, for the first time. The outer hydrogel layer endows the biomimetic periosteum with the ability to digitally coordinate its 3D geometry to match the specific macroscopic bone shape to maintain a bone healing microenvironment. The inner aligned human mesenchymal stem cells (hMSCs) layer not only promotes the migration and angiogenesis of co-cultured cells but also exhibits excellent osteogenic differentiation properties. In vivo experiments show that apart from morphing preset shapes as physical barriers, the aligned biomimetic periosteum can actively facilitate local angiogenesis and early-stage osteogenesis. Altogether, this present work provides a novel route to construct a personalized biomimetic periosteum with anisotropic microstructure by introducing a tunable shape to maintain the bone reconstruction microenvironment and this strategy can be extended to repair sophisticated bone defects.

Chronic intermittent hypoxia impaired collagen synthesis in mouse genioglossus via ROS accumulation: A transcriptomic analysis.

Obstructive sleep apnea (OSA) is a sleep-related breathing disorder characterized by intermittent and recurrent upper airway collapse during sleep that leads to chronic intermittent hypoxia (CIH). The genioglossus (GG) is the largest dilator muscle, which controls the upper airway and plays an important role in OSA pathology. Elucidating its genetic alterations may help identify potential targets for OSA. However, the genetic aspects of the GG in CIH mice remain unclear. Here, we have conducted an RNA sequencing (RNA-Seq) analysis to assess the differentially expressed genes (DEGs) in the GG between CIH mice and normoxia (NOR) mice. A total of 637 DEGs were identified to be dysregulated in CIH mice compared with control mice. Bioinformatics analysis showed that the DEGs were related to various physiological processes, such as the endogenous stimulus responses, cellular component organization and metabolic processes. Extracellular matrix (ECM)-receptor interaction was the top KEGG pathway in the environmental information processing category with high significance and large fold changes. From the gene weight distributions of collagen (Col)-related biological processes (BPs), we found several significant DEGs, such as Col1a1, Col1a2, Mmp2, Col3a1, Col5a1, Fmod, and Col5a2. A PPI network showed that Col1a1 was linked to ECM-receptor interactions, responses to reactive oxygen species (ROS) and Col-related BPs. It was verified in vivo and in vitro that hypoxia can induce excess ROS and reduce Col expression levels. Moreover, we found NAC can effectively scavenge ROS and restore collagen synthesis. These findings contribute to a better understanding of the mechanisms linking OSA and upper airway muscle injury and may help identify potential therapeutic targets.

Protective Effect of Genistein on Condylar Cartilage through Downregulating NF-κB Expression in Experimentally Created Osteoarthritis Rats.

Temporomandibular joint osteoarthrosis (TMJOA) is characterised by chronic inflammatory changes, with subsequent gradual loss of joint cartilage. NF-κB is a crucial transcription factor in the course of inflammatory and immune responses, which are involved in OA pathology activated by proinflammatory cytokines. Genistein is known to have anti-inflammation and modulation of metabolic pathways through repression of the NF-κB signaling pathway in inflammatory disease. But so far, studies on the effects of genistein on TMJOA are very limited. So, the purpose of this study is to investigate the protective effect of genistein against experimentally induced condylar cartilage degradation through downregulating NF-κB expression in created osteoarthritis rats in vivo. Male SD rats were created as temporomandibular joint osteoarthritis models and administered through oral gavage with low and high dosage genistein (30 mg/kg and 180 mg/kg, respectively) daily for 4 weeks. The morphological changes of the condylar cartilage were studied with HE and Masson staining. The expressions of p65 and inflammatory cytokines (IL-1ß and TNFα) were detected using immunohistochemistry and real-time PCR. The results showed that experimentally created osteoarthritis reduced the condylar cartilage thickness of rats and increased the gene expression of cytokines (IL-1ß and TNFα) and positive cells of p65. Genistein treatment had positive effects on the condylar cartilage renovation, while high dose genistein treatment had more significant effects on the reversing of OA changes and reduction of the expression of p65 and inflammatory cytokines (IL-1ß and TNFα). The results indicated that high dose genistein treatment had obvious therapeutic effects on condyle cartilage damages of OA rats. The mechanism may be that genistein suppresses the NF-κB expression activated by inflammatory cytokines.

Mechanical stretch-induced osteogenic differentiation of human jaw bone marrow mesenchymal stem cells (hJBMMSCs) via inhibition of the NF-κB pathway.

Severe malocclusion can contribute to several serious dental and physical conditions, such as digestive difficulties, periodontal disease, and severe tooth decay. Orthodontic treatment is mainly used to treat malocclusion. Forces in orthodontic tooth results in bone resorption on the pressure side and bone deposition on the tension side. Osteoblasts have been considered as the key component in bone regeneration on the tension side. However, the underlying mechanisms remain unclear. In this study, we focus on how mechanical stretch regulates the osteogenesis during orthodontic treatment. Human jaw bone marrow mesenchymal stem cells (hJBMMSCs) were isolated from healthy adult donors and cultured in regular medium (control) or osteogenic medium (OS). Under OS culture, hJBMMSCs presented osteogenic differentiation potentials, as evidenced by increased mineralization, enhanced calcium deposition, and upregulated expression of osteogenesis markers (ALP, osterix, and Runx). What's more, the OS-induced osteogenesis of hJBMMSCs is associated with the dephosphorylation of IKK, activation of IKBα, and phosphorylation/nucleic accumulation of P65, which all indicated the inhibition of NF-κB activity. Overexpressing P65 in hJBMMSCs, which could constantly activate NF-κB, prevented the osteogenic differentiation in the OS. After that, we applied the Flexcell tension system, which could cause mechanical stretch on cultured hJBMMSCs to mimic the tension forces during tooth movement. Mechanical stretch resulted in 3.5-fold increase of ALP activity and 2.4-fold increase of calcium deposition after 7 days and 21 days treatment, respectively. The expression levels of ALP, Run×2, and Osterix were also significantly upregulated. In the meantime, applying mechanical stretch on OS-cultured hJBMMSCs also dramatically promoted the OS-induced osteogenesis. Both OS and mechanical stretch downregulated NF-κB activity. By overexpressing P65 in hJBMMSCs, neither OS nor mechanical stretch could induce their osteogenesis. These results indicated that, like OS induction, mechanical stretch-facilitated osteogenesis of hJBMMSCs by inhibiting NF-κB in the noninflammatory environments.

Genistein Protects Genioglossus Myoblast Against Hypoxia-induced Injury through PI3K-Akt and ERK MAPK Pathways.

Obstructive sleep apnea and hypopnea syndrome (OSAHS) is a clinical syndrome characterized by recurrent episodes of obstruction of the upper airway during sleep that leads to a hypoxic condition. Genioglossus, an important pharyngeal muscle, plays an important role in maintaining an open upper airway for effective breathing. Our previous study found that genistein (a kind of phytoestrogen) protects genioglossus muscle from hypoxia-induced oxidative injury. However, the underlying mechanism is still unknown. In the present study, we examined the effects of hypoxia on genioglossus myoblast proliferation, viability and apoptosis, and the protective effect of genistein and its relationship with the PI3K/Akt and ERK MAPK pathways. Cell viability and Bcl-2 were reduced under hypoxic condition, while ROS generation, caspase-3, MDA, and DNA damage were increased following a hypoxia exposure. However, the effects of hypoxia were partially reversed by genistein in an Akt- and ERK- (but not estrogen receptor) dependent manner. In conclusion, genistein protects genioglossus myoblasts against hypoxia-induced oxidative injury and apoptosis independent of estrogen receptor. The PI3K-Akt and ERK1/2 MAPK signaling pathways are involved in the antioxidant and anti-apoptosis effect of genistein on genioglossus myoblasts.

Expression of hypoxia inducible factor-2 alpha in overloaded- stress induced destruction of mandibular condylar chondrocytes.

OBJECTIVE: To study the protein expression of HIF-2α in condylar chondrocytes under the different stress loading, to investigate the possible effects of HIF-2α involved in the mortality of condylar chondrocytes under overloaded- stress. MATERIALS AND METHODS: Chondrocytes were isolated from TMJ condylar cartilage and cultured in hypoxia-incubator. Chondrocytes were divided into 4 groups: 0, 1000, 2000, 3000 ustrain group, which was subjected to cyclic tensile strain (CTS) of 0.5Hz for 2h. The rate of cell mortality was calculated. Western blot was used to measure the expression of HIF-2α and it's downstream catabolic factors (MMP3, MMP13, ADAMTS4) in protein levels respectively. RESULTS: With the increase of CTS, both of the rate of cell mortality and protein expression of HIF-2α increased significantly (p<0.05). The same tendency was also found in it's downstream catabolic factors (MMP3, MMP13, ADAMTS4) in protein levels (p<0.05). CONCLUSIONS: The results indicated that elevated expression of HIF-2α may be a possible mechanism related to overloaded- stress induced mortality of condylar chondrocytes.

Expression of ADAMTs-5 and TIMP-3 in the condylar cartilage of rats induced by experimentally created osteoarthritis.

OBJECTIVE: To study the expression of ADAMTs-5 and TIMP-3 in temporomandibular joint osteoarthritis (TMJOA) model rats, to explore and confer the possible effects of ADAMTs-5 and TIMP-3 involved in the degradation of the early stage of OA. DESIGN: 32 SD rats were divided into four groups: 2-week control group (NC1), 2-week OA group (OA1), 4-week control group (NC2) and 4-week OA group (OA2). Each group had 8 rats. Injection of collagenase was used to build up the TMJOA model. HE staining was used to analyze the structural change of condyle cartilage. Western blot and RT-PCR were used to measure the expression of ADAMTs-5 and TIMP-3 in protein and mRNA levels respectively. RESULTS: HE analysis revealed that no significant changes were observed in NC1, NC2 and OA1 groups, while mild damages appeared in OA2 group. No significant differences were achieved in the expression of ADAMTs-5 in protein levels between NC1 and OA1, but the expression of ADAMTs-5 in 4-week group increased significantly compared to that in the NC2 group. On mRNA level, the expression of ADAMTs-5 in 2-week and 4-week OA groups increased significantly compared to that in the matched control group. Meanwhile, the expression of TIMP-3 decreased significantly, showing a completely different trend. CONCLUSIONS: The expression of ADAMTs-5 and TIMP-3 changed significantly in the early stage of TMJOA, which indicated that ADAMTs-5 and TIMP-3 may be play an important part in the initial stage of condylar cartilage degradation.

Volumetric measurement of root resorption following molar mini-screw implant intrusion using cone beam computed tomography.

OBJECTIVE: Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion. MATERIALS AND METHODS: 1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level. RESULTS: No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm(3). CONCLUSION: Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth.

Wisdom teeth: mankind's future third vice-teeth?

The third molar teeth (wisdom teeth) represent the last eruption of the teeth in the human dentition. Throughout evolution, the mandible has had a tendency to decrease in size; the third molar teeth are often impacted, resulting in incomplete tooth eruption that often causes clinical pericoronitis, dental caries, and pericemental abscess. Therefore, the wisdom teeth are often extracted. Moreover, wisdom teeth are often removed for clinical orthodontic treatment. On the other hand, tooth loss due to periodontal disease, dental caries, trauma, or a variety of genetic disorders continues to affect people's lives. Autologous tissues for dental tissue regeneration that could replace lost teeth could provide a vital alternative to currently available clinical treatments. To pursue this goal, we hypothesize that human third molar tooth buds can be obtained during development. Human wisdom tooth germination tissue could then be placed into an embryonic stem cell bank for storage. When the donor's other teeth are missing, embryonic stem cell and tissue engineering technologies, will permit the restoration of the missing teeth. Therefore wisdom teeth will be mankind's future third vice-teeth.

[An efficacy comparison between mini-screw implant and transpalatal arch on dentofacial morphology in extraction cases].

OBJECTIVE: To compare the effects between mini-screw implant and transpalatal arch (TPA) on dentofacial morphology in extraction cases. METHODS: Forty-two cases were divided into two groups. One group (n = 19) had been treated with mini-screw implants and the other group (n = 23) treated with TPA as anchorage control. Sliding technique was used to close extraction space in the two groups. Cephalometric analysis was performed before and after the treatment. The data were analyzed by using independent-samples t test. RESULTS: In the mini-screw implant group, the maxillary incisors were retracted (7.05 +/- 1.89) mm and intruded (1.71 +/- 2.33) mm, The maxillary first molars were distalized (0.45 +/- 3.32) mm and intruded (1.74 +/- 2.66) mm. While in the TPA group, the upper incisors were retracted (4.59 +/- 1.78) mm and extruded (0.93 +/- 1.77) mm. The maxillary first molars were moved (1.65 +/- 1.87) mm mesially and extruded (0.52 +/- 1.59) mm. All the relevant results between the two groups were significantly different (P < 0.05). CONCLUSIONS: As orthodontic anchorage, mini-screw implants were different from TPA. Mini-screw implant could not only retract the upper incisors but also slightly intrude upper incisors and upper molars.