Nickel-Catalyzed Selective C-H Cyanation via Aromatic Thianthrenium Salts.

Here, we report the first case of nickel-catalyzed C-H cyanation via arylthianthrenium salts. The reaction features the use of air-stable and inexpensive NiCl2·6H2O as a catalyst for the highly selective construction of cyanation products by aromatic pre-thianthrenation. The mechanism study shows that the formation of aryl radicals is involved. Also, this protocol can be applied to the late-stage functionalization of bioactive molecules and is readily scalable, further showcasing the synthetic utility.

[Three-dimensional finite element analysis of one-piece computer aided design and computer aided manufacture involved zirconia post and core].

OBJECTIVE: To analyze the biomechanics trait of one-piece computer aided design and computer aided manufacture (CAD/CAM) zirconia post and core by the Three-dimensional finite element. METHODS: The Three-dimensional finite element models of three upper central incisors restored with one-piece CAD/CAM zirconia post and core (group 1), refabricated zirconia post and hot-pressed porcelain core (group 2), and cast gold alloy post and core (group 3) were built by geometry method respectively. 100 N vertical loading through the central incisor models long axis and 100 N loading along directing at an angle of 45° with the models long axis were used to imitate the central incisor stress state in biting and mandible physiological protraction movement. RESULTS: Under vertical loading, the restored teeth without dentin ferrule, the maximum Von-Mises stress value of the tooth root in group 1 was the least(11.02 N), which was the largest (13.17 N)in group 2. The stress became weaker from the upper to the lower of the tooth root. The maximum Von-Mises stress value of the tooth root, post and core became smaller while the restored teeth with the 2.0 mm high dentin ferrule. Under directing at an angle of 45° loading, without the design of dentin ferrule in the restored teeth, the maximum Von-Mises stress value of the post and core in group 1 was the greatest(20.45 N), while that stress of post and core in group 3 was the smallest(13.61 N). With 2.0 mm high dentin ferrule design in the restored teeth, the tooth root stress became weaker. The maximum Von-Mises stress value of the tooth root was the greatest (14.10 N) in group 3, but which was the lowest (13.38 N) in group 1. CONCLUSION: The results of the Three-dimensional finite element analysis infers that one-piece zirconia post and core restoration is more beneficial to disperse the bite force than the prefabricated zirconia post and the cast gold alloy post and core. The one-piece of zirconia post and core is good to protect the teeth and keep the restoration intact.

[Comparison of soft and hard tissue stability between immediate implant and delayed implant in maxillary anterior region after loading 2 years].

OBJECTIVE: To compare the peri-implant tissue stability between immediate implant and delayed implant in maxillary anterior region after loading 2 years. METHODS: In the study, 38 patients with single anterior tooth loss in the Second Clinical Division of Peking University School and Hospital of Stomatology from October 2010 to December 2011 were enrolled, and 43 implants were inserted. The gingival contour was induced using implant-supported temporary crowns prior to restoration till permanent prostheses delivered. The gingival papilla height, labial gingival margin level and peri-implant bone level were measured immediately after the permanent restoration and 2 years later. RESULTS: In the study, 16 patients were treated by immediate implant for 17 implants; 22 patients were treated by delayed implant for 26 implants. The implant stability quotient (ISQ) value of the 2 groups showed no significant difference before permanent restoration (P>0.05). In all the cases after loading 2 years, the average mesial gingival papilla height in the implant area of the immediate group and delayed group increased by (0.15 ± 0.42) mm and (0.06 ± 0.65) mm, respectively; the distal gingival papilla height increased by (0.06 ± 0.50) mm and (0.02 ± 0.57) mm respectively; while the labial gingival margin level shrinkages were (0.15 ± 0.23) mm and (0.15 ± 0.46) mm, respectively. The peri-implant bone losses in the mesial side were (0.67 ± 0.35) mm and (0.6 9 ± 0.49) mm, respectively, while in the distal side were (0.73 ± 0.31) mm and (0.75 ± 0.48) mm, respectively. All these indicators showed no significant difference between the 2 groups (P>0.05). CONCLUSION: Both the cases obtained optimizer results after loading 2 years, and the soft and hard tissues around the implant were very stable, which means that both the protocols can achieve reliable therapeutic effects. If we can handle the indications, immediate implant for anterior teeth shows similar efficacy with delayed implant in the short term. But immediate implant in terms of shortening the course of treatment is clearly superior to delayed implant.

Carbon footprints: Uncovering multilevel spatiotemporal changes of ship emissions during 2019-2021 in the U.S.

Quantifying and understanding changes in carbon emissions is essential for the U.S. shipping industry to reduce carbon emissions, especially after its return to the Paris Agreement. We estimated carbon emissions from 48,321 ships in the U.S. Exclusive Economic Zone (EEZ) using the power-based method based on 3.6 billion Automatic Identification System (AIS) reports. We explored the characterization of carbon emissions from the national, regional, and port levels during 2019-2021 by allocating emissions on a 1 km*1 km grid through an activity-weighted method. The results show: (1) Due to the COVID-19 pandemic, emissions within the EEZ show a temporal trend of decreased and then rebound, specifically from 32.628 Tg in 2019 to 30.741 Tg in 2020 and then bounced to 31.786 Tg in 2021. The spatial differences in emissions show significant heterogeneity; (2) There are significant differences in emissions by vessel type, flag, and operational mode for the four regions of the U.S. (Great Lakes, Gulf Coast, Pacific Coast, and Atlantic Coast). Thus, emissions in these regions show different variability patterns over three years. Notably, "port congestion" led to record high emissions on the Pacific Coast; (3) Containerized cargo contributes the most to port core area emissions, so most ports with higher throughputs have higher emissions, with Long Beach and Los Angeles having the highest. Emissions from coastal ports are high and volatile, while inland ports are low and stable. This study provides the U.S. with a high spatiotemporal resolution inventory of carbon emissions from ships, and the findings are expected to provide some reference for controlling ship emissions.

[Evaluation of short-term clinical therapeutic efficiency of computer aided design and manufacturing titanium-ceramic-fixed partial dentures for implant-supported restoration in posterior region].

OBJECTIVE: To evaluate the clinical results of computer aided design and computer aided manufacturing (CAD/CAM) titanium-ceramic-fixed partial dentures for implant-supported restoration in posterior region. METHODS: In the study, 90 patients (47 males, 43 females, and the mean age of 48.7 years ranging from 30-62 years) with posterior tooth missing underwent implant-supported porcelain fuse mental prostheses with CAD/CAM titanium-base. A total of 135 prostheses (159 prosthetic units) were fabricated, and 152 implants were placed. The evaluators examined the integrity of restoration, gingival health, color match and marginal adaptation. The mean follow-up time was 51.9 months (24-80 months). RESULTS: No implant was lost during the loading time. All the patients were satisfied at the end of their treatment. The chipping rate of porcelain fuse mental prostheses with CAD/CAM titanium-base was 13.2%(21/159 prosthetic units), No fracture of titanium-base was observed, and 7.4% (10/135) prostheses were found loosening. The authors rated 97.8% (132/135) prosthesis as good or better in regard to color match, 100% (152/152) implants had excellent marginal adaptation. CONCLUSION: The implant-supported titanium-based porcelain fuse mental prostheses with CAD/CAM show good marginal integrity and shade stability, with a clinically acceptable chipping rate, and these restorations can achieve success in the case of posterior tooth missing. Further study is needed to determine the long-term results.

Hemodynamic impact of snoring on carotid artery after stent implantation: the role of oscillation.

Snoring is common in overweight and elderly patients treated by endovascular stenting. Studies have proved a correlation between snoring and carotid stenosis, thus, snoring after carotid artery stenting (CAS) might promote or worsen clinical performance. This study tested this hypothesis by constructing a patient-specific carotid bifurcation model and numerically analyzing hemodynamic changes of the carotid artery under different snoring conditions. These conditions included small and large amplitude, low and high frequency, and different age groups. The results found that high amplitude snoring suppressed the disturbed flow at the stented segment while the downstream region of ICA became more chaotic, accounting for in-stent intimal restenosis and thrombosis. Furthermore, local blood flow patterns of elder groups with snoring symptoms were more likely to be changed due to low-speed flow, increasing the possibility of vascular remodeling and thrombosis. Besides, increased snoring frequency hardly influenced the local disturbed flow. Therefore, older adults should receive medical treatment actively after stenting for high-amplitude snoring as soon as possible to avoid potential adverse events.

Fatigue cyclic loading test of an auro-galvanoforming ceramic bridge.

BACKGROUND: In dental clinics, dentition defects are commonly restored with conventional porcelain-fused-to-metal fixed bridges. However, Ni-Cr alloy ceramic fixed bridges are known to have several drawbacks such as marginal coloration of the neck, low casting precision and, most seriously, poor biocompatibility. These problems could be circumvented by using noble metal ceramic bridges; however, one negative issue related to the conventional noble metal ceramic bridges is its high price due to the use of a large amount of gold for pontic. Therefore, an auro-galvanoforming ceramic bridge would be ideal to retain the advantages of a conventional material, yet reduce the amount of noble metal used. This study aimed to investigate whether any destructive changes occur to the auro-galvanoforming ceramic bridge under a fatigue cyclic loading test. METHODS: On standard models which the left maxillary first premolar is lost and with the cuspid teeth and the second premolar as the fixed bridge abutment teeth, six maxillary auro-galvanoforming ceramic bridges and six corresponding nichrome ceramic jointed crowns were made as group A, six nichrome ceramic bridges and six corresponding nichrome ceramic jointed crowns were made as group B (control group). And then all specimens were fixed and tested on a fatigue cyclic loading machine; the changes occurring to the surfaces of occlusal contact with large functional area and to the porcelain-metal interfaces of the nichrome primary copings margins were observed through a scanning electron microscope (SEM). RESULTS: In 120 hours' continual observation, none of the specimens had porcelain coating fractures or scraping occurrence and all of the porcelain coatings had been kept intact under sinusoidal cyclic loading with the load range of 120 - 200 N and frequency of 5 Hz. CONCLUSIONS: Auro-galvanoforming ceramic bridges exhibited excellent fatigue strength in the fatigue cyclic loading test and may satisfy the clinical demand in theory, while the practical application shall be evaluated by observations in long-term clinical usage.

The evaluation of the carbon fiber post system on restoration of teeth defect in children.

BACKGROUND: Post and post-core systems are used to restore extensively damaged teeth. Among these systems, cast alloy post and core, prefabricated threaded alloy post and prefabricated simple alloy post are most frequently applied in China nowadays. In Europe and North America a combined application of the fiber post, resin-core and crown has been applied to restore seriously destructed teeth with satisfactory results in recent years. This study was intended to evaluate the clinical effect of carbon fiber post system on restoration of child anterior tooth defect after root canal therapy, based on 3 - 5 years' observation. METHODS: One hundred and six children with incompletely established occlusion were observed and followed for an average of 42 months (ranging from 36 to 60 months). Eighty-five upper teeth and forty-one lower teeth were restored with carbon fiber post system and composite jacket crown. Periodic check-up was conducted for periodontal condition and restoration effect. RESULTS: One hundred and twenty-one (96.2%) restorations were successful. Four jacket crowns (3.0%) were lost. One tooth (0.8%) had slight gingival inflammation. Tooth root or post fracture and gingival stain were not observed. X-ray showed there was no obvious change in aspects including the width of periodontal membrane, the density of alveolar bone and the height of alveolar ridge crest. CONCLUSIONS: Carbon-fiber post system can satisfy the clinical requirements of young patients who have residual anterior crown and root caused by trauma or caries, and have incomplete occlusion and have completed root canal therapy. This system helps realize good esthetic result for patients and easy practice for dentists. Carbon fiber post is safe and convenient, especially for sick children.

Evaluation of the therapeutic efficiency of mandibular anterior implant-supported fixed bridges with cantilevers.

BACKGROUND: Dental implant technology has developed rapidly in recent years. However, the use of implant-supported fixed bridges with cantilevers has been controversial. The purpose of this study was to evaluate the clinical results of the mandibular anterior implant-supported fixed bridges with a cantilever. Method Thirty-three patients (15 males, 18 females; mean age, 42.6 years; range 20-54 years) with two missing anterior mandibular teeth had single implant-supported fixed bridges with a cantilever. Clinical examination was recorded and radiographs were taken. The mean duration of follow-up was 30 months (15-44 months). RESULTS: All implants survived. Loosening or fracture of the prosthesis was not observed. All patients were satisfied with the treatment. The mean bone resorption values after 12, 24, and 36 months of implant loading were 0.94, 1.18 and 1.35 mm respectively. The changes of gingival papilla height ranged from 0 to 0.5 mm. There was significant difference between 1-year and 2 or 3 years restoration groups regarding the average gingival height changes (P < 0.05). CONCLUSION: After careful and precise selection of patients, restoration with a single implant-supported fixed bridge with a cantilever can be recommended if two anterior mandibular teeth are missing.

Clinical follow-up of ceramic bridges with auro-galvanoforming primary coping and Ni-Cr pontic for restoration of dentition defects.

BACKGROUND: Alternatives to the conventional auro-galvanoforming ceramic bridge need to be evaluated in long-term longitudinal studies before being recommended for restoration of dentition defects. This study aimed to evaluate the clinical performance of a ceramic bridge with auro-galvanoforming primary coping and Ni-Cr pontic for restoration of dentition defects. METHODS: In total, 114 ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) were placed in 112 patients with dentition defects. Among them, 83 bridges in 82 patients were available for follow-up after 7 years. We evaluated marginal integrity, color match, gingival inflammation, fracture of ceramic bridges, and recurrent caries. RESULTS: Marginal integrity of the ceramic bridges was perfect in all patients. Most ceramic bridges maintained their original color. Fracture was found in three bridges; the rest were free of fracture, breakage, and loosening. Recurrent abutment caries were not found. Ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) produced satisfactory clinical outcomes - equivalent to the conventional porcelain-fused-to-metal restoration. This technique is especially useful for dentition defects of the molar area and is cheaper than restoration with noble metal bridges. CONCLUSIONS: Ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) performed well for the restoration of dentition defects during this follow-up period. More studies are warranted to further evaluate this technique as an alternative to the conventional porcelain-fused-to-metal restoration.

[The 6-year clinical comparison of compound galvano-ceramic bridges with gold alloy and Ni-Cr alloy ceramic bridges].

OBJECTIVE: To evaluate and compare effects of compound galvano-ceramic bridges with Ni-Cr alloy ceramic bridges and gold alloy ceramic bridges in clinic. METHODS: A total of 105 bridges were made for 103 patients. Of them, 35 were compound galvano-ceramic bridges, 35 Ni-Cr alloy ceramic bridges, and 35 gold alloy ceramic bridges respectively. The marginal fitness and fracture of ceramic bridges were checked and caries or second caries of all abutments were also examined in clinic at 6 years after cementation. RESULTS: The marginal fitness of compound galvano-ceramic bridges was evaluated as good in 100% of the bridges, which was better than the fitness of gold alloy ceramic bridges (91%) and Ni-Cr alloy ceramic bridges (77%) (P < 0.01). There was no difference in fracture of ceramic layer among compound galvano-ceramic, gold alloy ceramic, and Ni-Cr alloy ceramic bridges at 6 years (P > 0.05). None of compound galvano-ceramic bridge was found out caries or second caries of abutments. Two of 35 (6%) gold alloy ceramic bridges was found out second caries of abutments and five of 35 (14%) Ni-Cr alloy ceramic bridges were found out caries or second caries of abutments at 6 years. None of frameworks of all bridges was loose or broken. CONCLUSIONS: The 6-year clinical study on compound galvano-ceramic bridges presents good results in marginal fitness and fracture resistance, which indicates the compound galvano-ceramic bridge can be used in clinic.

[The measurement and comparison of shear fracture strength and shear bond strength between carbon fiber post and some other posts].

OBJECTIVE: The shear fracture strengths of carbon fiber post, IPS-Empress 2 all-ceramic post (without ZrO2 post), cast Ni-Cr alloy post, prefabricated zirconia ceramic post, human dentin and the shear bonding strengths of the first three kinds of post bonded in the human root canals were measured and compared, which are as the reference for dental clinic. METHODS: Standard cylindrical samples were made respectively in each group of carbon fiber post, IPS-Empress 2 all-ceramic post, cast Ni-Cr alloy post, prefabricated zirconia ceramic post, human dentin, three for each group. The shear fracture strengths of these samples were measured by universal testing machine (AUTOGRAPH DCS5000). Standard cylindrical samples were made respectively in each group of carbon fiber post, IPS-Empress 2 all-ceramic post (without ZrO2 post), cast Ni-Cr alloy post, five for each group. They were bonded in extracted human root canals that had been prepared to 3.0 mm length and 2.0 mm diameter with Glass ionomer cement (Japan Shofu). The shear bond strengths were measured by the same universal testing machine. RESULTS: The shear fracture strengths of the carbon fiber post (199MPa), cast Ni-Cr alloy post (210MPa, shear bend strength) and prefabricated zirconia ceramic post (193MPa) were statistically higher than those of IPS-Empress 2 all-ceramic post (109MPa) and human dentin (100MPa). The shear fracture strength of the carbon fiber post was statistically similar to that of cast Ni-Cr alloy post and prefabricated zirconia ceramic post. There were no statistical differences between the shear bond strengths of carbon fiber post (2.4MPa) and cast Ni-Cr alloy post (3.8MPa). IPS-Empress 2 all-ceramic post broke before debonding (2.7, break value). CONCLUSIONS: Carbon fiber post, as well as cast Ni-Cr alloy post and prefabricated zirconia ceramic post, has a comparatively high shear fracture strength. The shear bond strengths of carbon fiber post is similar to cast Ni-Cr alloy post.