ObjectiveTo observe the effects of Yangjing Zhongyutang （YJZYT） on mitochondrial biogenesis and oxidative stress damage mediated by the silent information regulator 1 （SIRT1）/peroxisome proliferator-activated receptor gamma coactivator-1alpha （PGC-1α） signaling pathway in cyclophosphamide （CTX）-induced rats with diminished ovarian reserve （DOR）， and to explore its mechanism in improving ovarian reserve function and follicular development. MethodsForty-two 8-week-old female SD rats with normal estrous cycles were randomly divided into a blank control group （n=7） and a model group （n=35）. Rats in the model group received a single intraperitoneal injection of CTX （90 mg·kg^-1） to establish the DOR model. After modeling， estrous cycles were monitored for 7 consecutive days， and model success was confirmed based on criteria for estrous cycle disruption. After successful modeling， rats were divided into groups for intervention： estradiol valerate group （0.09 mg·kg^-1）， and YJZYT high-， medium-， and low-dose groups （19.98， 9.99， 5.00 g·kg^-1）. The blank control group and model group were given an equal volume of distilled water by gavage. All groups received daily gavage once for 4 consecutive weeks. The general state， body weight， and ovarian wet weight of rats were observed and recorded， and the ovarian organ index was calculated. Enzyme-linked immunosorbent assay （ELISA） was used to measure serum levels of follicle-stimulating hormone （FSH）， luteinizing hormone （LH）， estradiol （E₂）， anti-Müllerian hormone （AMH）， superoxide dismutase （SOD）， and glutathione peroxidase （GSH-Px）. Hematoxylin-eosin （HE） staining was performed to observe ovarian histomorphological changes and follicular development status. Immunofluorescence was used to detect reactive oxygen species （ROS） expression levels. Colorimetric assays were employed to measure adenosine triphosphate （ATP） and malondialdehyde （MDA） content in ovarian tissues. Quantitative Real-time polymerase chain reaction （Real-time PCR） was used to detect mitochondrial DNA （mtDNA） copy number and the mRNA expression levels of key genes including SIRT1， PGC-1α， nuclear respiratory factor 1 （NRF1）， and mitochondrial transcription factor A （TFAM）. Western blot was performed to detect the protein expression levels of SIRT1， PGC-1α， NRF1， and TFAM. ResultsCompared with the blank group， rats in the model group exhibited disrupted estrous cycles， obviously reduced body weight， and decreased ovarian index （P<0.05）. Ovarian histopathology revealed cortical thinning， loose structure， and a significant reduction in both primordial and growing follicles （P<0.01）. Serum FSH and LH levels were significantly elevated （P<0.01）， while E₂ and AMH levels were obviously reduced （P<0.05， P<0.01）. ATP content and mtDNA copy number decreased in ovarian tissue （P<0.01）， ROS expression increased， MDA levels rose， while SOD and GSH-Px activities obviously decreased （P<0.05， P<0.01）， mRNA and protein expression levels of SIRT1， PGC-1α， NRF1， and TFAM were obviously downregulated （P<0.05， P<0.01）. After treatment， compared with the model group， body weight and ovarian index obviously recovered in rats administered various doses of YJZYT （P<0.05）， serum E₂ and AMH levels increased， while FSH and LH levels obviously decreased （P<0.05， P<0.01）， ovarian tissue ATP content and mtDNA copy number were up-regulated， ROS and MDA levels decreased， and antioxidant enzymes SOD and GSH-Px activity obviously increased （P<0.05， P<0.01）， Gene and protein expression levels related to the SIRT1/PGC-1α /NRF1/TFAM signaling pathway were obviously up-regulated compared to the model group （P<0.05， P<0.01）， HE staining revealed that ovarian structure gradually recovered to integrity in all treatment groups， with a obviously increase in the number of primordial and growing follicles （P<0.05， P<0.01）. Granulosa cells were neatly arranged， indicating marked improvement in ovarian function. ConclusionYJZYT may improve ovarian function and follicular development in rats with diminished ovarian reserve by activating the SIRT1/PGC-1α signaling pathway， promoting mitochondrial biogenesis， enhancing mitochondrial function， and alleviating oxidative stress damage.

ObjectiveTo evaluate the clinical efficacy of Shenqi Yangxin decoction in the treatment of ischemic cardiomyopathy （ICM） with Qi and Yin deficiency and blood stasis syndrome and its effect on serum hydrogen sulfide （H₂S） and calcium ion （Ca²⁺）. MethodsA total of 64 ICM patients with Qi and Yin deficiency and blood stasis syndrome who met the inclusion criteria were randomly divided into a control group （n=32） and a treatment group （n=32）. All patients received conventional Western medicine treatment. The treatment group was additionally given Shenqi Yangxin decoction. The TCM syndrome score， Minnesota Living with Heart Failure Questionnaire （MLHFQ） score， left ventricular ejection fraction （LVEF）， N-terminal pro-B-type natriuretic peptide （NT-proBNP）， 6-minute walk test （6MWT）， New York Heart Association （NYHA） cardiac function classification， and serum H₂S and Ca²⁺ levels were compared between the two groups pre- and post-treatment. ResultsTwo cases dropped out from each group during the study. Finally， 30 patients in each group were included in the analysis. There were no significant differences in age， gender， course of coronary heart disease， underlying diseases， and laboratory tests between the two groups. Compared with baseline， the TCM syndrome score， MLHFQ score， and NT-proBNP in both treatment group and control group decreased significantly （P<0.01）， LVEF， 6MWT， and H₂S increased significantly （P<0.01）， and serum Ca²⁺ increased （P<0.05）. Compared with the control group after treatment， the MLHFQ score and NT-proBNP in the treatment group decreased （P<0.05）， the TCM syndrome score decreased significantly （P<0.01）， LVEF， 6MWT， and serum Ca²⁺ increased （P<0.05）， and H₂S increased significantly （P<0.01）. The improvement degree of the NYHA cardiac function classification in the treatment group was higher than that in the control group， but there was no significant difference. ConclusionShenqi Yangxin decoction is effective in treating ICM patients with Qi and Yin deficiency and blood stasis， which could significantly improve cardiac function and quality of life， and its therapeutic effect may be related to the regulation of serum H₂S and Ca²⁺ levels.

Objective To identify factors affecting and key environmental factors of the Oncomelania hupensis snail density in the Yangtze River Delta region using machine learning methods. Methods Administrative village-level O. hupensis snail survey data in the Yangtze River Delta (including Shanghai Municipality, Jiangsu Province, Zhejiang Province and Anhui Province) from 2011 to 2021 were retrieved from the Information Management System for Parasitic Disease Control of Chinese Center for Disease Control and Prevention. Environmental factor data were captured from the Google Earth Engine platform, including elevation, slope, terrain, normalized difference vegetation index (NDVI), vegetation type, soil type, total petroleum hydrocarbon (TPH), ammonium nitrogen, inorganic nitrogen, dissolved oxygen, pH of water, chemical oxygen demand (COD) and inorganic phosphorus, and climatic factor data in the study region were retrieved from the Copernicus Climate Data Store, including annual precipitation, aridity index and annual mean temperature (AMT). O. hupensis snail survey data in the Yangtze River Delta region from 2011 to 2021 were randomly divided into a training set (70%) and a test set (30%), and five machine learning models were selected for machine learning model construction and comparative analysis of the O. hupensis snail density using the software R 4.3.0, including random forest (RF), eXtreme gradient boosting (XGBoost), support vector machine (SVM), gradient boosting machine (GBM) and neural network (NN). The XGBoost model was employed to construct a predictive model for the O. hupensis snail density, and the impact of each environmental factor on O. hupensis snail distribution was quantified. The SHapley Additive exPlanations (SHAPs) values were calculated to estimate the average contribution of each variable to the model prediction, and the core environmental factors affecting the O. hupensis snail population density were screened. Results Among the five machine learning models, the XGBoost model exhibited the optimal comprehensive performance, with the coefficient of determination (R²) of 0.855, mean squared error (MSE) of 0.188, root mean squared error (RMSE) of 0.434 and mean absolute error (MAE) of 0.155, respectively. Analysis of factors affecting the O. hupensis snail density with the XGBoost model showed that among the 16 environmental factors, the top four high-impact factors ranked by SHAPs values included annual precipitation, elevation, aridity index and NDVI, with cumulative SHAPs contributions of 75%, which was higher than that of other environmental factors. If NDVI was higher than 0.6, the O. hupensis snail density increased with NDVI and peaked if NDVI was 0.8 (1.60 snails/0.1 m²). The O. hupensis snail density increased with elevation if the elevation ranged from 14 to 40 m, and slowly rose if the annual precipitation ranged from 900 to 1 300 mm, and then increased rapidly to the peak (1.52 snails/0.1 m²) if the annual precipitation ranged from 1 300 to 1 500 mm. In addition, the O. hupensis snail density increased rapidly to the maximum (1.60 snails/0.1 m²) if the aridity index ranged from 0.8 to 1.1, and decreased gradually if the aridity index exceeded 1.1. Conclusions The XGBoost model shows excellent performance in prediction of the O. hupensis snail density and identification of key environmental factors in the Yangtze River Delta region. Annual precipitation, elevation, aridity index and NDVI are key environmental factors affecting the distribution and density of O. hupensis snails in the Yangtze River Delta region.

The frequent extreme climatic events post multifaceted impacts on the distribution of Oncomelania hupensis, the intermediate host of Schistosoma japonicum in the context of global climate change. This article systematically reviews the effects of four types of extreme climatic events, including floods, droughts, heat waves, and cold waves, on the survival, reproduction, and distribution of Oncomelania hupensis. Floods may expand suitable snail habitats, and increase both emerging and re-emerging snail habitats; however, the impact of floods on O. hupensis density is characterized by a lag effect of a decline followed by a rise. Droughts may cause fragmentation of suitable O. hupensis snail habitats, reduced O. hupensis snail egg production rates, and increased O. hupensis snail mortality, and heat waves may cause an increase in O. hupensis snail mortality, a reduction in numbers of O. hupensis snail populations and shrinking of O. hupensis snail distribution, while cold waves may cause a reduction in O. hupensis snail density and a rise in O. hupensis snail mortality. Extreme climate events pose both shortand long-term effects on the distribution of O. hupensis. Intensified surveillance of O. hupensis snails is required in high-risk environments.

ObjectiveTo investigate the chemical constituents of Chuanxiong Rhizoma-Paeoniae Radix Rubra（CRPRR） that cross the blood-brain barrier in rats with ischemic stroke， their brain-protective effects， and their impact on inflammatory factors including tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18） based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry （UPLC-Q-TOF-MS） and pharmacodynamic experiments. MethodsA focal cerebral ischemia-reperfusion injury model was established in rats via the middle cerebral artery occlusion/reperfusion （MCAO/R） method using intraluminal suture. Neurological function was evaluated using behavioral scoring. UPLC-Q-TOF-MS was employed to identify the chemical constituents of CRPRR that crossed the blood-brain barrier and entered the cerebrospinal fluid in MCAO/R model rats. Male Sprague-Dawley rats were randomly divided into six groups： sham operation group， model group， low-， medium-， and high-dose CRPRR groups （1.35， 2.7， 5.4 g·kg^-1， respectively）， and an edaravone group （5 mg·kg^-1）， with 12 rats in each group. The sham and model groups received normal saline， while the treatment groups received the respective doses of CRPRR once daily by gavage for three consecutive weeks. The brain-protective effects of CRPRR were assessed using the Longa five-point scoring method， open field test， Morris water maze， 2，3，5-triphenyltetrazolium chloride （TTC） staining， hematoxylin and eosin （HE） staining， and transmission electron microscopy. ResultsNine chemical constituents were identified in the cerebrospinal fluid containing CRPRR， namely paeoniflorin， senkyunolide F， senkyunolide G， paeonimetabolin Ⅰ， paeoniflorin derivative， senkyunolide H， benzoylpaeoniflorin， senkyunolide A， and ligustilide. Animal experiment results showed that compared with the sham operation group， the model group exhibited disordered neuronal arrangement， severe vacuolation， nuclear pyknosis， and evident mitochondrial swelling. Chromatin aggregation and peripheralization were also observed. Neurological scores and the number of crossings in the central region were significantly increased （P<0.01）， while platform crossings were significantly decreased （P<0.01）， and clear infarct areas were present （P<0.01）. Serum levels and protein expression of TNF-α， IL-1β， and IL-18 were significantly elevated （P<0.01）. Compared with the model group， all dose groups of CRPRR showed marked improvement in neuronal morphology which was close to the normal level， with mitochondrial swelling alleviated and chromatin distribution more uniform. The medium- and high-dose groups significantly reduced neurological scores （P<0.01）， while the low-， medium-， and high-dose groups significantly reduced the number of central crossings （P<0.01） and infarct volume （P<0.01）， and decreased TNF-α， IL-1β， and IL-18 levels （P<0.05， P<0.01） compared with the model group. Furthermore， the medium- and high-dose groups significantly reduced TNF-α protein expression （P<0.05，P<0.01）， and the high-dose group significantly reduced IL-1β and IL-18 protein expression （P<0.01）. ConclusionThis study confirmed that CRPRR improves neurological function and alleviates brain tissue damage in MCAO/R rats. Its mechanism may be associated with the downregulation of inflammatory factors TNF-α， IL-1β， and IL-18， as well as the presence of nine active chemical constituents in cerebrospinal fluid， namely paeoniflorin， senkyunolide F， senkyunolide G， paeonimetabolin Ⅰ， paeoniflorin derivative， senkyunolide H， benzoylpaeoniflorin， senkyunolide A， and ligustilide， which are closely related to their brain-protective effects.

ObjectiveTo investigate the chemical constituents of Chuanxiong Rhizoma-Paeoniae Radix Rubra（CRPRR） that cross the blood-brain barrier in rats with ischemic stroke， their brain-protective effects， and their impact on inflammatory factors including tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18） based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry （UPLC-Q-TOF-MS） and pharmacodynamic experiments. MethodsA focal cerebral ischemia-reperfusion injury model was established in rats via the middle cerebral artery occlusion/reperfusion （MCAO/R） method using intraluminal suture. Neurological function was evaluated using behavioral scoring. UPLC-Q-TOF-MS was employed to identify the chemical constituents of CRPRR that crossed the blood-brain barrier and entered the cerebrospinal fluid in MCAO/R model rats. Male Sprague-Dawley rats were randomly divided into six groups： sham operation group， model group， low-， medium-， and high-dose CRPRR groups （1.35， 2.7， 5.4 g·kg^-1， respectively）， and an edaravone group （5 mg·kg^-1）， with 12 rats in each group. The sham and model groups received normal saline， while the treatment groups received the respective doses of CRPRR once daily by gavage for three consecutive weeks. The brain-protective effects of CRPRR were assessed using the Longa five-point scoring method， open field test， Morris water maze， 2，3，5-triphenyltetrazolium chloride （TTC） staining， hematoxylin and eosin （HE） staining， and transmission electron microscopy. ResultsNine chemical constituents were identified in the cerebrospinal fluid containing CRPRR， namely paeoniflorin， senkyunolide F， senkyunolide G， paeonimetabolin Ⅰ， paeoniflorin derivative， senkyunolide H， benzoylpaeoniflorin， senkyunolide A， and ligustilide. Animal experiment results showed that compared with the sham operation group， the model group exhibited disordered neuronal arrangement， severe vacuolation， nuclear pyknosis， and evident mitochondrial swelling. Chromatin aggregation and peripheralization were also observed. Neurological scores and the number of crossings in the central region were significantly increased （P<0.01）， while platform crossings were significantly decreased （P<0.01）， and clear infarct areas were present （P<0.01）. Serum levels and protein expression of TNF-α， IL-1β， and IL-18 were significantly elevated （P<0.01）. Compared with the model group， all dose groups of CRPRR showed marked improvement in neuronal morphology which was close to the normal level， with mitochondrial swelling alleviated and chromatin distribution more uniform. The medium- and high-dose groups significantly reduced neurological scores （P<0.01）， while the low-， medium-， and high-dose groups significantly reduced the number of central crossings （P<0.01） and infarct volume （P<0.01）， and decreased TNF-α， IL-1β， and IL-18 levels （P<0.05， P<0.01） compared with the model group. Furthermore， the medium- and high-dose groups significantly reduced TNF-α protein expression （P<0.05，P<0.01）， and the high-dose group significantly reduced IL-1β and IL-18 protein expression （P<0.01）. ConclusionThis study confirmed that CRPRR improves neurological function and alleviates brain tissue damage in MCAO/R rats. Its mechanism may be associated with the downregulation of inflammatory factors TNF-α， IL-1β， and IL-18， as well as the presence of nine active chemical constituents in cerebrospinal fluid， namely paeoniflorin， senkyunolide F， senkyunolide G， paeonimetabolin Ⅰ， paeoniflorin derivative， senkyunolide H， benzoylpaeoniflorin， senkyunolide A， and ligustilide， which are closely related to their brain-protective effects.

Objective: To evaluate the platelet transfusion requirements in children with high-risk stage Ⅳ neuroblastoma undergoing autologous hematopoietic stem cell transplantation (ASCT), and to identify risk factors for increased transfusion needs and prolonged time to platelet transfusion independence. Methods: This single-center retrospective clinical study included 96 children with high-risk stage Ⅳ neuroblastoma who underwent ASCT from January 2019 to May 2024 in our hospital. Relevant clinical data were collected and analyzed, including age, gender, body surface area, platelet count (PLT) on stem cell infusion day (day 0), conditioning regimen, CD34 stem cell dose, platelet transfusion requirements during transplantation, and time to platelet transfusion independence post-transplant. Results: All 96 (100%) children received transfusion after ASCT. From day 0 to transfusion independence, the median number of platelet transfusion was 3 (2, 4.50), and the median volume of platelet transfused was 3 (2, 4.25) units. Platelet transfusion was required in almost all children in pseudo-healing stage (day 4 to day 6) and polar stage (day 7 to day 14), with transfusion rates as high as 83.33%(n=80) and 100%(n=96), respectively. The median time to platelet transfusion independence post-transplant was 13(11,17) days. Multivariate analysis showed that PLT<100×10 /L on day 0, platelet transfusion within one week before ASCT, the use of “busulfan+ melphalan” conditioning regimen, and CD34 stem cell dose<4.0×10 /kg were associated with significantly increased platelet requirements and numbers of transfusion (P<0.05). PLT<100×10 /L on day 0, platelet transfusion within one week before ASCT, and CD34 stem cell dose<4.0×10 /kg were associated with significantly delayed platelet transfusion independence (P<0.05). Age, sex, and blood type showed no statistically significant association (P>0.05) with post-transplant platelet transfusion requirements or time to transfusion independence in neuroblastoma patients. Conclusion: This study provided quantitative data for platelet transfusion after ASCT in children with high-risk stage Ⅳ neuroblastoma, and identified PLT<100×10 /L on day 0, platelet transfusion within one week before ASCT, CD34 stem cell dose<4.0×10 /kg were risk factors for increased platelet transfusions and delayed transfusion independence. Furthermore, the use of the BuMel (busulfan-melphalan) conditioning regimen was also found to contribute to increased transfusion requirements.

OBJECTIVE: To investigate the effectiveness of using 3 hollow compression screws combined with 1 screw off-axis fixation under the guidance of three-dimensional (3D) printed guide plate with mortise-tenon joint structure (mortise-tenon joint plate) for the treatment of Pauwels type Ⅲ femoral neck fractures. METHODS: A clinical data of 78 patients with Pauwels type Ⅲ femoral neck fractures, who were admitted between August 2022 and August 2023 and met the selection criteria, was retrospectively analyzed. The operations were assisted with mortise-tenon joint plates in 26 cases (mortise-tenon joint plate group) and traditional guide plates in 28 cases (traditional plate group), and without guide plates in 24 cases (control group). There was no significant difference in the baseline data of gender, age, body mass index, cause of injury, and fracture side between groups ( P>0.05). The operation time, intraoperative blood loss, frequency of intraoperative fluoroscopy, incision length, incidence of postoperative deep vein thrombosis of lower extremity, pain visual analogue scale (VAS) score at 1 week after operation, and Harris score of hip joint at 3 months after operation were recorded and compared. X-ray re-examination was taken to check the quality of fracture reduction, fracture healing, and the shortening length of the femoral neck at 3 months after operation, and the incidences of internal fixation failure and osteonecrosis of the femoral head during operation. RESULTS: Compared with the control group, the operation time, intraoperative blood loss, and frequency of intraoperative fluoroscopy reduced in the two plate groups, and the quality of fracture reduction was better, but the incision was longer, and the differences were significant ( P<0.05). The operation time and intraoperative blood loss were significantly higher in the traditional plate group than in the mortise-tenon joint plate group ( P<0.05), the incision was significantly longer ( P<0.05); and the difference in fracture reduction quality and the frequency of intraoperative fluoroscopy was not significant between two plate groups ( P>0.05). There was 1 case of deep vein thrombosis of lower extremity in the traditional plate group and 1 case in the control group, while there was no thrombosis in the mortise-tenon joint plate group. There was no significant difference in the incidence between groups ( P>0.05). All patients were followed up 12-15 months (mean, 13 months). There was no significant difference in VAS score at 1 week and Harris score at 3 months between groups ( P>0.05). Compared with the control group, the fracture healing time and the length of femoral neck shortening at 3 months after operation were significantly shorter in the two plate groups ( P<0.05). There was no significant difference between the two plate groups ( P>0.05). There was no significant difference in the incidences of non-union fractures, osteonecrosis of the femoral head, or internal fixation failure between groups ( P>0.05). CONCLUSION For Pauwels type Ⅲ femoral neck fractures, the use of 3D printed guide plate assisted reduction and fixation can shorten the fracture healing time, reduce the incidence of postoperative complications, and be more conducive to the early functional exercise of the affected limb. Compared with the traditional guide plate, the mortise-tenon joint plate can reduce the intraoperative bleeding and shorten the operation time.
Humans ; Femoral Neck Fractures/diagnostic imaging* ; Bone Plates ; Fracture Fixation, Internal/instrumentation* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Bone Screws ; Adult ; Aged ; Treatment Outcome ; Printing, Three-Dimensional ; Operative Time

B and T lymphocyte attenuator (BTLA) is an inhibitory immune checkpoint, which typically interacts with herpesvirus entry mediator (HVEM) and plays a crucial role in regulating immune balance. BTLA interacts with its ligand HVEM in a cis manner on the surface of the same immune cell to maintain immune tolerance, while trans interactions on the surface of different immune cells mediate immunosuppressive effects. Dysregulation of the BTLA/HVEM axis can impair the functions of immune cells, particularly T lymphocytes, promoting immune escape of tumor cells and ultimately leading to tumor progression. Researchers have found that BTLA and HVEM are abnormally expressed in various tumors and are associated with prognosis, suggesting that they may be potential targets for tumor immunotherapy. This review summarizes the molecular structures of BTLA and HVEM, immunomodulatory mechanisms, recent advances in hematologic malignancies, potential inhibitors of BTLA/HVEM interaction, and their applications in immunotherapy for hematologic malignancies.
Humans ; Receptors, Tumor Necrosis Factor, Member 14/chemistry* ; Receptors, Immunologic/immunology* ; Hematologic Neoplasms/genetics* ; Immunotherapy/methods* ; Animals

OBJECTIVE: To establish a three-dimensional finite element model of a digital wire loop space maintainer for the mandible and primary tooth loss, in order to investigate the stress, deformation, and shear force experienced by patients with the loss of the second primary molar when wearing the wire loop space maintainer. METHODS: Cone beam computed tomography (CBCT) scans were performed on the patients to create a digital model of the mandible with the absence of the second primary molar using Mimics 21.0 software. A digital model integrating the crown's retention and the wire loop structure of the full crown and ring wire loop space maintainer was constructed using pediatric space maintainer design software, utilizing three different materials: cobalt-chromium alloy, polyether ether ketone (PEEK), and titanium alloy. In ANSYS Work Beach 2023 R2 software, vertical loads of 70 N, tilted 45° along the long axis of the tooth loads of 70 N, and a 10 N load on the surface of the wire loop were applied to the occlusal surfaces of models 46 and 84, simulating centric and lateral occlusions during chewing with the wire loop space maintainer in place. The stress states of the wire loop space maintainer and supporting teeth were analyzed. RESULTS: Under various loading conditions, the maximum principal stress of the ring wire loop space maintainer was significantly lower than that of the full crown. Stress contour maps indicated that the peak of the maximum principal stress occurred at the junction of the wire loop and crown structure, indicating that this area was more susceptible to fracture. The ring wire loop space maintainer made from PEEK material exhibited the lowest maximum shear stress on the internal organizational surfaces, with equivalent stresses of 23.18 MPa and 36.35 MPa for models 46 and 84, respectively. Stress contour maps demonstrated that the maximum stress on tooth 46 was located at its mesial, while the maximum stress on tooth 84 was situated near the root area on its distal, in contact with the wire loop space maintainer. CONCLUSION In cases of second primary molar loss, wearing the digital ring wire loop space maintainer can effectively distribute stress, and the ring wire loop space maintainer made from PEEK material reduces the stress experienced by supporting teeth to some extent, demonstrating its superiority in clinical application.
Finite Element Analysis ; Humans ; Tooth, Deciduous ; Cone-Beam Computed Tomography ; Space Maintenance, Orthodontic/methods* ; Imaging, Three-Dimensional ; Orthodontic Wires ; Dental Stress Analysis ; Mandible ; Stress, Mechanical