An analysis of the optimal intrusion force of the maxillary central incisor with root horizontal resorption using the finite element method and curve fitting.

There are no studies on the optimal intrusion force in orthodontic patients with the existing root resorption (RR). The study aimed to analyze the optimal intrusion force for central incisors with existing horizontal root resorption using the finite element method (FEM). We calculated the optimal intrusion force using the finite element method and curve fitting. We found that with the increase of the maxillary central incisor's root horizontal resorption length, the optimal intrusion force interval's median gradually increases. If the resorption length is more significant than 1/2 of the root length, it is not recommended to use intrusion force theoretically.

[Imaging characteristic of Stafne bone cavity：a retrospective study based on cone-beam CT].

PURPOSE: To guide clinical decision-making more efficiently via collecting and analyzing the imaging data of patients with Stafne bone cavity(SBC). METHODS: Six patients with SBC were retrospectively reviewed in Stomatological Hospital of Shandong University. By assessing cone-beam CT (CBCT) data, age, sex, complaint, cavity location, diameter at three dimension, maximal cross-sectional area of multi-planar reconstruction planes, content gray scale, morphological classification and its relationship with mandibular canal were recorded respectively. RESULTS: A total of 6 cases were inadvertently found on CBCT, with no symptoms. The locations of SBC were between mandibular molar region and mandibular angle, inferior border of mandible and mandibular canal, mostly at lingual side. Three were on the left and three were on the right. The bone cavity was elliptic and its long axis was consistent with the long axis of the mandible, with an average long axis diameter of (16.43±4.54) mm, horizontal axis diameter of (6.91±1.48) mm, vertical axis diameter of (10.24±2.10) mm. According to the multi-planar reconstruction planes readings, the maximal cross-sectional area of the bone cavity was (91.93±25.52) mm2, the maximal coronal area was (57.26±23.23) mm2, and the maximal sagittal area was (127.80±51.22) mm2. In view of the classification in the relationship between SBC marginal line and buccal cortical bone, there were 2 cases of type I cavity, 3 cases of type II cavity and 1 case of type III cavity. The connection between the bone cavity and the surrounding anatomical structure was classified into 3 conditions: covering penetration, adjacency and separation on the basis of the relative position between the cavity boundary with the mandibular inferior margin and the mandibular canal in sagittal plane. In addition, the content type could be primarily identified depending on estimation of corrected grey scale in the center of bone cavity. CONCLUSIONS: CBCT can make an intuitive and clear diagnosis of Stafne bone cavity, which brings great significance into the early clinical decision-making, thus not only avoiding unnecessary surgery, reducing the waste of additional medical resources, but also decreasing the physical and mental trauma of patients.

Prolonged viral shedding in feces of pediatric patients with coronavirus disease 2019.

OBJECTIVE: To determine the dynamic changes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory and fecal specimens in children with coronavirus disease 2019 (COVID-19). METHODS: From January 17, 2020 to February 23, 2020, three paediatric cases of COVID-19 were reported in Qingdao, Shandong Province, China. Epidemiological, clinical, laboratory, and radiological characteristics and treatment data were collected. Patients were followed up to March 10, 2020, and dynamic profiles of nucleic acid testing results in throat swabs and fecal specimens were closely monitored. RESULTS: Clearance of SARS-CoV-2 in respiratory tract occurred within two weeks after abatement of fever, whereas viral RNA remained detectable in stools of pediatric patients for longer than 4 weeks. Two children had fecal SARS-CoV-2 undetectable 20 days after throat swabs showing negative, while that of another child lagged behind for 8 days. CONCLUSIONS: SARS-CoV-2 may exist in children's gastrointestinal tract for a longer time than respiratory system. Persistent shedding of SARS-CoV-2 in stools of infected children raises the possibility that the virus might be transmitted through contaminated fomites. Massive efforts should be made at all levels to prevent spreading of the infection among children after reopening of kindergartens and schools.

The relationship between endothelial progenitor cells and pulmonary arterial hypertension in children with congenital heart disease.

BACKGROUND: Pulmonary arterial hypertension (PAH) caused by congenital heart disease (CHD) is very common in clinics. Some studies have shown that PAH is related to the number of endothelial progenitor cells (EPCs), but there is no report on the relationship between PAH and the number of EPCs in children with CHD. METHODS: In this study, a total of 173 cases with CHD (from 0 to 6 years old) were collected. According to the mean pulmonary arterial pressure (mPAP) measured by right heart catheterization, these cases were divided into PAH groups (including high PAH group, mPAP> 25 mmHg, n = 32, and the middle PAH group, 20 mmHg ≤ mPAP≤25 mmHg, n = 30) and non-PAH group (mPAP< 20 mmHg, n = 111). Peripheral blood was taken for flow cytometry, and the number of EPCs (CD133+/KDR+ cells) was counted. The number of EPCs /µL of peripheral blood was calculated using the following formula: EPCs /µL = WBC /L × lymphocytes % × EPCs % × 10- 6. RESULTS: The median EPCs of the non-PAH group, middle PAH group and high PAH group is 1.86/µL, 1.30 /µL and 0.98/µL, respectively. The mPAP decreases steadily as the level of EPCs increases (P < 0.05). After adjustment of gender, age and BMI, the number of EPCs was significantly associated with a decreased risk of high PAH (OR = 0.37, 95% CI: 0.16-0.87, P < 0.05). However, EPCs was not significantly associated with middle PAH (P > 0.05). CONCLUSION: The findings revealed that the EPCs and high PAH in patients with CHD correlate significantly and EPCs may become an effective treatment for PAH in patients with CHD. EPCs may be a protective factor of high PAH for children with CHD.

Factors associated with prehospital delay in patients with ST-segment elevation acute myocardial infarction in China.

BACKGROUND: Prehospital delay is the most critical factor to prognosis of ST-elevation myocardial infarction (STEMI). Few study had examined a series of predictors of prehospital delay by multivariate analysis of sociodemographic and clinical characteristics, onset features, and symptom condition of STEMI in China. METHODS: A total of 1088 hospitalized STEMI participants were screened to collect sociodemographic data, medical history information, and symptom onset status from clinical medical records. Factors associated with prehospital delay were examined using bivariate and multivariate analysis method. RESULTS: The median prehospital delay time (PDT) was 130 minutes in STEMI participants. Multivariate regression models examining 8 predictors were associated with prehospital delay, including senior high school or above educational level, myocardial infarction (MI) history, vertigo onset symptom, ambulance transportation, onset in daytime (6:00-18:00), onset at home, anterior wall MI, and posterior wall MI. Mortality in PDT more than 120 minutes group was 5.5%, whereas it was 4.3% in PDT 120 minutes of less group without significant statistically difference (P > .05). CONCLUSIONS: Multivariate analysis results found that symptom onset-related variables strongly influenced PDT. Onset-related status of STEMI needed to be combined into interventions of participants, and more emergency education should be recommended to both participants and their relatives. Most importantly, more efforts should be taken to educate the public about the symptoms and signs to increase the recognition of STEMI.

[Construction of keratinocyte growth factor phage active peptides for the promotion of epidermal cell proliferation].

OBJECTIVE: To construct and display the keratinocyte growth factor (KGF) phage active peptides so as to detect the promoting effects of epidermal cell. METHODS: KGF sequences were chosen and their primers were designed. The selected genes of P1, P2 and P4 were obtained by reverse transcription (RT)-PCR. P3 was obtained by direct synthesis. And the KGF genes were subcloned into pComb3 vector. The technique of phage display was employed to display the genes on phage surface. Methyl thiazolyl tetrazolium (MTT) assay was used to evaluate the promoting effects of KGF phage active peptides on the proliferation of epidermal cell. Optical density (A) was determined at 570 nm. Immunofluorescent assay was employed to evaluate the cell affinity of KGF phage active peptides. RESULTS: The four KGF genes were obtained and subcloned into pComb3 vector. The proteins of the KGF genes were expressed on the surface of the pComb3 vector. The MTT data of optical density (A) showed that significant differences existed between the negative control and KGF control (0.293 ± 0.017 vs 0.520 ± 0.043) and KGF phage active peptide groups (0.293 ± 0.017 vs 0.469 ± 0.057, 0.441 ± 0.048, 0.438 ± 0.035, 0.446 ± 0.037) (all P < 0.01). The results of immunofluorescent assay indicated that KGF and KGF phage active peptides had excellent cell affinity. CONCLUSION: KGF phage active peptides are successfully constructed and displayed and they may promote the proliferation of epidermal cell.

Association between mandibular posterior alveolar morphology and growth pattern in a Chinese population with normal occlusion.

OBJECTIVE: To investigate the relationship between growth patterns and mandibular posterior tooth-alveolar bone complex morphology in a Chinese population with normal occlusion. METHODS: Forty-five patients with normal occlusion (23 males, 22 females) were included in this study. Among these patients, 20 displayed the vertical growth pattern, and 20 had the horizontal growth pattern, while the remaining patients displayed the average growth pattern. All of the patients underwent dental cone beam computed tomography (CBCT), which included the region of the mandibular posterior teeth and the alveolar. A linear regression analysis and a correlation analysis between the facial height index (FHI) and the alveolar bone morphology were performed. RESULTS: The inclination of the molars, the thickness of the cortical bone, and the height of the mandibular bone differed significantly between patients with the horizontal growth pattern and those with the vertical growth pattern (P<0.05). Significant positive correlations were found between: the FHI and the inclination of the molars; the FHI and the thickness of the cortical bone; and the FHI and the height of the mandibular bone. CONCLUSIONS: The mandibular posterior tooth-alveolar bone complex morphology may be affected by growth patterns.

Transcription factor osterix modified bone marrow mesenchymal stem cells enhance callus formation during distraction osteogenesis.

This study was designed to investigate the effects of local delivery of bone marrow mesenchymal stem cells (BMMSCs) with or without osterix (OSX) gene transfected on bone regeneration in the distracted zone using a rabbit model of mandibular lengthening. Fifty-four New Zealand white rabbits underwent osteodistraction of the left mandible and were then randomly divided into group A, group B, and group C (n = 18 for each group). At the end of distraction BMMSCs transfected with OSX, autologous BMMSCs and physiological saline were injected into the distraction gaps in groups A, B, and C, respectively. Nine animals from each group were humanely killed at 2 and 6 weeks after completion of distraction. The distracted mandibles were harvested and processed for radiographic, histological, and immunohistochemical examination. Excellent bone formation in the distracted callus was observed in group A and group B; the former showed better bone formation and highest bone mineral density (BMD), thickness of new trabeculae (TNT, mm) and volumes of the newly formed bone area (NBV) in the distraction zones. Group C animals showed poor bone formation in the distracted callus when compared with groups A and B. Positive immunostaining of bone sialoprotein (BSP) was observed in the distracted callus in all groups; however, BSP expression was much stronger in group A than in groups B and C. The results of this study suggest transplantation of BMMSCs can promote bone formation in DO; OSX-mediated ex vivo gene therapy was more effective during bone deposition and callus formation in distraction osteogenesis.

Transarterial embolization of a high-flow maxillary arteriovenous malformation fed by multiple arteries.

A high-flow maxillary arteriovenous malformation fed by multiple arteries, including bilateral internal maxillary arteries and ophthalmic artery, is reported. A combination of polyvinyl alcohol particles and N-butyl-cyanoacrylate mixed with lipiodol was progressively deposited within the distal vascular bed by transarterial superselective embolization of the branches of bilateral internal maxillary arteries, resulting in complete anatomic and clinical cure. The authors feel that this approach is more secure and effective compared with transfemoral venous embolization and direct transosseous puncture. It also avoids mutilating surgery.

[Mandibular keratocyst induced trigeminal neuralgia: report of one case].

Trigeminal neuralgia is very common in clinic, but the etiology is still unclear. This articles reported a case of trigeminal neuralgia induced by jaw keratocyst. The clinical manifestation, radiographic characteristic, pathologic diagnosis and treatment were discussed. It is concluded that jaw bone cavities may be one of the major etiologic factors of secondary trigeminal neuralgia. Surgical curettage of the lesion is the main treatment for this disease.

[Experimental study of mandibular periosteal distraction in rabbits].

OBJECTIVE: To investigate a novel technique for new bone formation--periosteal distraction osteogenesis. METHODS: A custom made periosteal distraction device was fixed to bilateral surface of the mandible in three rabbits. Periosteal distraction was performed on the left side of the mandible, the right side of the mandible served as the control. The animals were sacrificed at the end of distraction process. All the specimens were X-rayed and histologically examinated. RESULTS: All three animals survived with no obvious complications. Both in mass specimens and X-rays, there showed new bone formation on the distracted side of the mandible. In histological examinations, there was osteoblast-like cell infiltration and bone tissue formation in the distracted area. CONCLUSION: Periosteal distraction osteogenesis can provide a novel technique for the repair of bone defects.

[Repair of mandibular central fissures in rabbits with hBMP-2 gene modified tissue engineered bone].

PURPOSE: To evaluate the effectiveness of the tissue engineered bone substitute loaded with periosteal-derived osteoblasts (POBs) transfected by adenovirus mediated human bone morphogenetic protein-2 gene (Ad-hBMP-2) in the repair of rabbit mandibular central fissures. METHODS: 45 rabbits with the soft tissue in the mandibular central fissures removed were randomly divided into 5 groups, group I: Ad-hBMP-2 transfected POBs/bioglass group (n=10); group II: adenovirus mediated enhanced green fluorescent protein (Ad-EGFP) gene transfected POBs/bioglass group (n=10); group III: untransfected POBs/bioglass group (n=10); group IV: single bioglass group (n=10); group V: control group (n=5). The above bone substitutes were implanted in the rabbit mandibular central fissures respectively except group V. The samples were studied by gross, X-ray, histomorphology, histomorphometrical analysis and biomechanics after 2, 4, 8, 12 weeks respectively. One-way ANOVA was used for statistical analysis. RESULTS: In gross view, the rabbit mandibular central fissures in group I were replaced by new bone including cortical bone from the 4th week. X-ray examination showed that the higher bone density was found in the rabbit mandibular central fissures of group I 4 to 8 weeks after implantation. Histomorphometrical analysis showed much more new bony callus in group I than in other groups (P<0.01). The maximal anti-bending load and bending rigidity of the implanted bone substitute of group I were significantly higher than those of group II, III and IV (P<0.01). CONCLUSION: The tissue engineered bone substitute loaded with POBs transfected by human BMP-2 gene could get the best result in the repair of rabbit mandibular central fissures, therefore, it is likely to be used in the repair of alveolar clefts.

[The experimental study of cryopreserved osteoblasts combined with BGC repairing mandibular defects in rabbits].

OBJECTIVE: The purpose of this study was to observe the biological characteristics of cultured Periosteal-derived Osteoblasts (POBs) preserved in liquid nitrogen in vitro, and to preliminarily study the osteogenetic capability of bioactive glass ceramic (BGC) combined with POBs. METHODS: The cryopreserved cells were cultured in DMEM medium and examined by morphological and histological assay. The POBs growing well in vitro were seeded into the porous BGC materials. A week later, the combined materials were implanted into the bone defects of rabbits' mandibular, the control groups were implanted into the single BGC (no cells). After 2, 4, 8, 12 weeks of operation, the specimens were respectively excised and examined by X-ray and histological chemistry. RESULTS: The cryopreserved POBs grew well in vitro and also had the tipical characteristics of mature osteoblasts. Cultured with BGC materials, the cells could attach, grow and proliferate well on the surface of most endoporous. After 4 weeks of operation, the transplanted osteoblasts began to form new osteoid or bone tissue in most pores of implanted BGC, and the bone defects were repaired better and earlier. CONCLUSION: It was practical to use the cryopreserved osteoblasts for further study on bone tissue engineering. It suggested that the "life active" bone would get more application and play a more important role in bone restoration and reconstruction.