Study of the mandibular canal and its surrounding canals by multi-view cone-beam computed tomography.

OBJECTIVES: To determine the mandibular anatomical structures by observing cone-beam computed tomography (CBCT) from multiple angles. MATERIALS AND METHODS: This retrospective study analyzed 1593 consecutive CBCT images. Ultimately, 95 CBCTs met the inclusion criteria. The mandibular, inferior lingual, and bony canals at the tooth apex were studied by multi-angle observation CBCT. Descriptive statistics were used for statistical analysis. RESULTS: It is beneficial to further observe the anastomosis of the mandibular, lingual, and mandibular canals when the course of the mandibular lingual canal is observed on CBCT cross-section. The frequency of the inferior lingual canal anastomosis with the mandibular canal was 43.2% (95% confidence interval (CI) 33, 53.3) in the sample. The mental foramen was located below the long axis of the tooth in a few samples, with an occurrence rate of 29.5% (95% CI 20.1, 38.8). The occurrence rate of various types of the bony canal at the apex of the tooth in canines, first premolars, second premolars, first molars, and second molars under the root apex was recorded through the multi-angle observation of the dental volume reformat (DVR) and three-dimensional (3D) levels in CBCT. CONCLUSION: This study demonstrates the utility of CBCT imaging in examining mandibular anatomy from multiple angles, providing valuable insights into anatomical variations, and enhancing our understanding of mandibular structures. This research emphasizes the crucial role of meticulous CBCT examination in precisely identifying and understanding key anatomical structures, ultimately reducing the risk of surgical complications. CRITICAL RELEVANCE STATEMENT: By examining cone-beam computed tomography scans from various perspectives, it is possible to determine the precise position of anatomical structures within the jaw. This allows for a more accurate assessment, reducing the risk of harm to these structures during treatment. KEY POINTS: • It is crucial to utilize image data effectively to enhance the comprehension of human anatomy. • We captured detailed images of the mandible from different angles and orientations utilizing cone-beam computed tomography (CBCT). • This study provides essential anatomical information for procedural planning to ensure optimal outcomes and patient safety.

Evaluation of the distribution characteristics of the mandibular lingual foramen and its potential risks during implant surgery using cone-beam computed tomography a cross-sectional, retrospective study.

OBJECTIVES: The lingual foramen is a risk factor for implantation and other mandibular surgeries, but there are few systematic studies on the anatomical and distribution characteristics of the lingual foramen in the entire mandible. MATERIALS AND METHODS: A retrospective study was performed using 405 CBCT images. The anatomical characteristics and symmetrical distribution of the mandibular lingual foramen were analyzed. RESULTS: All patients had at least one lingual foramina. According to the positional relationship between the mandibular lingual foramen and the root apex of tooth, the mandibular lingual foramen is divided into the upper lingual foramen and the lower lingual foramen. Upper lingual foramen were divided into three types according to its running direction, namely Type 1 (Enters the mandible and descend in the direction of the lower edge of the mandible), Type 2 (Enters the mandible and descends in the direction of the lower edge of the mandible with branches), and Type 3 (It enters the mandible and divides into two branches, one ascends toward the crest of the alveolar ridge, and the other descends toward the lower edge of the mandible). And their respective prevalence are 84.0% [95% Tolerance Limit (TL) 81.2%-86.8%], 9.9% [95% TL 7.6%-12.1%], and 6.1% [95% TL 4.3%-8.0%]. In addition, the 81.8% [95% TL 79.0%-84.7%] of the upper lingual foramen is distributed in the central incisor area. Lower lingual foramen were divided into three categories according to the running direction, namely Category 1 (Enters the mandible and ascends toward the buccal bone plate), Category 2 (Enters the mandible and descends toward the buccal bone plate), and Category 3 (Go straight into the mandible toward the buccal bone plate). And their respective prevalence are 29.6% [95% TL 26.4%-32.7%], 50.9% [95% TL 47.5%-54.4%] and 19.5% [95% TL 16.8%-22.3%]. The frequency of lower lingual foramen distributed anteriorly to the mental foramen is 55.8% [95% TL 52.3%-59.2%], mid-mental foramen is 21.4%[95% TL 18.5%-24.2%], and posterior to the mental foramen is 22.8% [95% TL 20.0%-25.8%]. CONCLUSION: Both the upper and lower lingual foramina should be evaluated in the anterior, middle, and posterior regions of the mental foramen before implant surgeries.

General distributed activation energy model (G-DAEM) on co-pyrolysis kinetics of bagasse and sewage sludge.

In this work, pyrolysis kinetic evolution of mixture of bagasse and sewage sludge with 10%, 30% and 50% (respect to dry initial weight). In terms of kinetic mechanism, the uncertainty of the activation energy obtained by mode-free method was barely known. We found that increasing number of heating rates made result more reliable, but the modeling process more dependent on redundant experiments with extra data. We adapted a novel general distributed activation energy model (G-DAEM) with 5 pseudocomponents for the analysis of kinetic evolution with proposing a more applicable approximation to the general temperature integral. The G-DAEM was trained by data for 20 K/min, and the predictions were performed on data for 15 K/min and 25 K/min. The predictions were well matched to the experimental data. The G-DAEM enhances modeling efficiency of kinetics and provides a effective pathway for high precise model of complicated co-pyrolysis process.

Co-pyrolysis kinetics of sewage sludge and bagasse using multiple normal distributed activation energy model (M-DAEM).

In this study, the kinetic models of bagasse, sewage sludge and their mixture were established by the multiple normal distributed activation energy model. Blending with sewage sludge, the initial temperature declined from 437 K to 418 K. The pyrolytic species could be divided into five categories, including analogous hemicelluloses I, hemicelluloses II, cellulose, lignin and bio-char. In these species, the average activation energies and the deviations situated at reasonable ranges of 166.4673-323.7261 kJ/mol and 0.1063-35.2973 kJ/mol, respectively, which were conformed to the references. The kinetic models were well matched to experimental data, and the R2 were greater than 99.999%y. In the local sensitivity analysis, the distributed average activation energy had stronger effect on the robustness than other kinetic parameters. And the content of pyrolytic species determined which series of kinetic parameters were more important.

Thermal behavior of vehicle plastic blends contained acrylonitrile-butadiene-styrene (ABS) in pyrolysis using TG-FTIR.

As important plastic blends in End-of-Life vehicles (ELV), pyrolysis profiles of ABS/PVC, ABS/PA6 and ABS/PC were investigated using thermogravimetric-Fourier transform infrared spectrometer (TG-FTIR). Also, CaCO3 was added as plastic filler to discuss its effects on the pyrolysis of these plastics. The results showed that the interaction between ABS and PVC made PVC pyrolysis earlier and HCl emission slightly accelerated. The mixing of ABS and PA6 made their decomposition temperature closer, and ketones in PA6 pyrolysis products were reduced. The presence of ABS made PC pyrolysis earlier, and phenyl compounds in PC pyrolysis products could be transferred into alcohol or H2O. The interaction between ABS and other polymers in pyrolysis could be attributed to the intermolecular radical transfer, and free radicals from the polymer firstly decomposed led to a fast initiation the decomposition of the other polymer. As plastic filler, CaCO3 promoted the thermal decomposition of PA6 and PC, and had no obvious effects on ABS and PVC pyrolysis process. Also, CaCO3 made the pyrolysis products from PA6 and PC further decomposed into small-molecule compounds like CO2. The kinetics analysis showed that isoconversional method like Starink method was more suitable for these polymer blends. Starink method showed the average activation energy of ABS50/PVC50, ABS50/PA50 and ABS50/PC50 was 186.63kJ/mol, 239.61kJ/mol and 248.95kJ/mol, respectively, and the interaction among them could be reflected by the activation energy variation.

Experiment and simulation study on alkalis transfer characteristic during direct combustion utilization of bagasse.

Bagasse is utilized as fuel in the biggest biomass power plant of China, however, alkalis in the fuel created severe agglomeration and slagging problems. Alkalis transfer characteristic, agglomeration causes in engineering practice, additive improvement effects and mechanism during bagasse combustion were investigated via experiments and simulations. Only slight agglomeration occurs in ash higher than 800°C. Serious agglomeration in practical operation should be attributed to the gaseous alkalis evaporating at high temperature and condensing on the cooler grain surfaces in CFB. It can be speculated that ash caking can be avoided with temperature lower than 750°C and heating surface corrosion caused by alkali metal vapor can be alleviated with temperature lower than 850°C. Kaolin added into the bagasse has an apparent advantage over CaO additive both in enhancing ash fusion point and relieving alkali-chloride corrosion by locking alkalis in dystectic solid compounds over the whole temperature range.