MOF-Derived Zn/N-Doped Porous Carbon Film on a Carbon Nanotube for High-Performance Supercapacitors.

Designing high-performance binder-free electrochemical electrodes is crucially important toward supercapacitors. In this paper, a Zn/N-doped porous carbon film coating on flexible carbon nanotubes (ZIF-8@CT-800) derived from the epitaxial Zn-MOF film growth on cotton textile was successfully fabricated via a combination of the liquid-phase epitaxial (LPE) method and calcination treatments. The ZIF-8@CT-800 serves directly as a self-supported electrode for supercapacitors and exhibits a high areal capacitance of 930 mF·cm-2 at a current density of 1 mA·cm-2 and a good recyclability of 86% after 2000 cycles. The excellent supercapacitor property is ascribed to the unique structural design of ZIF-8@CT-800, which provides appropriate channels for enhanced electronic and ionic transport as well as increased surface area for accessing more electrolyte ions. This work will provide significant guidance for designing MOF-derived porous carbon to construct flexible binder-free electrode materials with high electrochemical performance.

[An analysis of the wall width before and after root canal therapy in mandibular second molars with C-shaped canals].

PURPOSE: To measure the wall width in mandibular second molars with C-shaped canals before and after root canal therapy using cone-beam CT(CBCT). METHODS: A total of 55 mandibular second molars from 38 patients which met the criteria for inclusion at Nanjing Stomatological Hospital, Affiliated Stomatological Hospital of Medical School of Nanjing University from January 2020 to July 2021 were analyzed．From this sample, ten teeth had been treated, while another 45 of them not. CT images of the teeth were reestablished by Mimics software 20.0. Then we made a section every 1mm perpendicular to the long axis of the teeth from apex to pulp floor. The first slice from apex to pulp chamber was named the slice 1. Along the slice 1 to crown 1 mm was called slice 1, and so forth. The wall thickness at different locations of all the slices was measured. The data was entered into SPSS 20.0 software package for analysis. RESULTS: Regardless of whether the teeth were treated or not, both the mesial and distal canal walls' average width were thicker than 1mm in all slices. At the same time, the mesial and distal canal walls' width were thicker than the width of buccal and lingual canal walls in all the slices from C-shaped root canal, except slices which were near pulp chamber(P＜0.05). As for the C-shaped root canals without root canal therapy, the width of lingual wall in the slice 1 to 4, as well as apex third root, was thinner than 1 mm. The width of buccal canal wall was thicker than the width of lingual canal wall in all slices except slice 11 and 12. As for the C-shaped root canals with root canal therapy, the width of buccal canal wall in slice 1 to 5, equivalent of apex half root, and the width of lingual wall in the slice 1 to 7, amount to apex two-thirds of root, was thinner than 1 mm. The width of buccal canal wall was thicker than the width of lingual wall in all slices except slice 1 and 9. There was no significant difference between the distal canal walls' width of C-shaped canals with and without root canal therapy(P＞0.05) . There was significant difference between the buccal canal walls' width of C-shaped canals with and without root canal therapy, as same as the mesial canal walls' width and the width of lingual canal wall (P＜0.05). CONCLUSIONS: The lingual canal walls' width in apex third root of C-shaped root canal were thin before canal preparation. The buccal walls' width in apex half root and the lingual canal walls' in apex two-thirds of root of C-shaped root canal were thin after canal preparation.

Oral and maxillofacial pain as the first sign of metastasis of an occult primary tumour: A fifteen-year retrospective study.

BACKGROUND: Metastatic adenocarcinoma of the jaw (MAJ) is a rare disease that accounts for 1%-3% of all oral and maxillofacial malignant tumours. Oral and maxillofacial pain may be the first symptom of metastatic spread of an occult primary tumour. Therefore, early identification of oral and maxillofacial pain by dental professionals is critical. AIM: To explore the clinical and computerized tomography (CT) features of MAJ with oral and maxillofacial pain as the first symptom. METHODS: The medical records of all patients who were treated in our hospital between January 2006 and February 2020, and diagnosed with MAJ with oral and maxillofacial pain as the first symptom, were reviewed retrospectively. Clinical data were collected on age, sex, medical history, clinical manifestations, site of metastasis, and site of the primary lesion. CT features were analysed in detail, and a radiological classification scheme comprising five types: Osteolytic, osteoblastic, mixed, cystic, and alveolar bone resorption was proposed. RESULTS: The primary sites of MAJ were the lungs (n = 6), liver (n = 4), kidneys (n = 2), prostate (n = 1), and gastric cardia (n = 1). Five tumours were classified as the osteolytic type, all with a permeative margin (100%, P < 0.05), and three were classified as the mixed type, mostly with a moth-eaten margin (80%, P < 0.05). The cystic (n = 3) and alveolar bone resorption (n = 1) types had geographic margins, and the osteoblastic type (n = 1) had sclerotic margins. Moreover, nine tumours showed periosteal reaction and five showed a localised soft tissue mass, while the occurrence of jaw expansion was relatively rare. CONCLUSION: MAJ has complex clinical and CT features. Oral and maxillofacial pain may be the first sign of a primary tumour affecting other sites.

Relationship between canal morphology and isthmus in mesio-buccal roots of maxillary first molars in 9- to 12-year-old children: An in-vivo cone-beam computed tomography analysis.

OBJECTIVES: This study aims to analysis the distribution of root canal isthmuses (RCIs), and its relationship with canal morphology in the mesio-buccal roots of maxillary first molars in children aged 9-12 in a Chinese sub-population. METHODS: 494 healthy, untreated maxillary first molars with fully developed mesio-buccal roots were examined. Cone-beam computed tomography (CBCT) scans were acquired as part of diagnosis and treatment plannings unrelated to the present study. The images were evaluated to identify the canal morphology of mesio-buccal roots according to Vertucci's classification. A map-reading strategy was used to identify RCIs. RESULTS: In mesio-buccal roots, the most common canal morphology was type Ⅳ (38.5 %). The frequency of type I (1.6 %) was much lower than adults. RCIs were found in 92.5 % mesio-buccal roots. The RCIs which began in the cervical third and ended in the middle third (CT-MT) (31.0 %) had the highest frequency. In type III, the RCIs which began and ended in the middle third (MT-MT) (30.3 %) were most common. For type V, 30.8 % RCIs began in the cervical third and ended in the apical third (CT-AT). No significant differences were found between sexes and sides (P > 0.05). CONCLUSIONS: For children aged 9-12, the frequency of type I canals was much lower in mesio-buccal roots of maxillary permanent first molars, while the frequency of RCIs was higher than adults, especially in the apical third. The distribution of RCIs had its own characteristics in each canal type, closely related to the structures.

[Comparative study of root canal morphology of mandibular incisors by cone-beam CT and canal staining and clearing technique].

PURPOSE: To compare the root canal morphology of mandibular incisors by using cone-beam CT (CBCT) and canal staining and clearing technique. METHODS: Sixty-one extracted mandibular incisors with complete dental root and apex which received no endodontic treatment and no post crown restoration were selected. Each tooth was radiographed with CBCT, and the root canal system was stained by canal staining and clearing technique. The consistency of the number of root canal, root canal Vertucci type of mandibular permanent incisors between the two methods were compared, and the differences of the detection rate on root canal branch structure between the two methods were analyzed. The results were statistically analyzed with SPSS 17.0 software package. RESULTS: The Kappa value of single and double root canal types between CBCT and canal staining and clearing technique was 0.847 (P<0.001). The Kappa value of Vertucci root canal types between CBCT and canal staining and clearing technique was 0.861 (P<0.001). The detection rates of root canal branch structure were 8.19% and 22.95%, respectively, with significant difference between the two methods (P=0.025). The canal staining and clearing technique was significantly better than CBCT in detection of root canal branch structure. CONCLUSIONS: CBCT can reflect the root canal types nearly perfectly, but inferior to canal staining and clearing technique in detection of root canal branch structure, CBCT is a relatively accurate clinical diagnosis tool of root canal morphology.

[Analysis of mandibular bone mineral density of senile osteoporosis patients].

OBJECTIVE: To investigate the mandibular bone mineral density (BMD) change of senile osteoporosis patients and the relationship between the mandible bone loss and systemic bone loss. METHODS: Forty senile osteoporotic patients (group A), 40 non-osteoporosis control elders (group B) and 40 healthy youths (group C) were included in this study. Standard digital panoramic tomography (SDPTG) was taken for each participant. Cortical width (CW), panoramic mandibular index (PMI), alveolar bone density and alveolar bone height were measured on the SDPTG. Lumbar and hip BMD were measured with dual energy X-ray absorptiometry (DXA). RESULTS: Close relationship was found between CW (3.57 +/- 0.82) and systemic BMD for osteoporosis patients (P < 0.05). All the SDPTG indices including CW, PMI, alveolar bone density and alveolar bone height were different for osteoporosis patients from the healthy youths (P < 0.05). The osteoporosis patients had thinner CW (3.57 +/- 0.82) and smaller PMI (0.29 +/- 0.06) than non-osteoporosis control elders (CW: 4.07 +/- 0.75, PMI: 0.32 +/- 0.07, P < 0.05). The alveolar bone density (105.40 +/- 20.48) and alveolar bone height (10.42 +/- 1.82) of the non-osteoporosis control elders reduced compared with the healthy youths (alveolar bone density: 117.10 +/- 22.23, alveolar bone height: 11.69 +/- 1.63, P < 0.05). CONCLUSIONS: The senile osteoporotic patients had significant mandibular cortical bone loss.

[Evaluation of mandibule bone loss of periodontitis with standard digital panoramic tomogram].

OBJECTIVE: To compare the mandibular indices differences between periodontitis and non-periodontitis subjects by digital panoramic tomograms in order to find a simple and effective method to evaluate the density of alveolar bone and study the relativity between local bone loss and systemic bone loss. METHODS: Standard digital panoramic tomograms of sixty periodontitis subjects and sixty non-periodontitis subjects were taken. Density and height cortical width (CW) and panoramic mandibular index (PMI) of alveolar bone were measured on the digital panoramic tomograms. SPSS 12.0 was used for statistics analyses. RESULTS: The periodontitis subjects had lower height of alveolar bone (8.76 mm vs. 11.85 mm, P=0.000), lower density of alveolar bone (106.08 vs. 113.33, P=0.034), thinner cortical width (3.80 mm vs. 4.27 mm, P=0.008), while the difference of PMI between the two groups was not significant (P>0.05). The relativity between both density and height of alveolar bone with CW was significant (P<0.05), but not significant with PMI (P>0.05). CONCLUSION: The optical method is a simple and effective method to measure the density of the alveolar bone. Compared with the non-periodontitis subjects, the periodontitis subjects not only have alveolar bone changed significantly but also have thinner cortical width.