The α-amino acid ester acyltransferase (SAET) from Sphingobacterium siyangensis is one of the enzymes with the highest catalytic ability for the biosynthesis of l-alanyl-l-glutamine (Ala-Gln) with unprotected l-alanine methylester and l-glutamine. To improve the catalytic performance of SAET, a one-step method was used to rapidly prepare the immobilized cells (SAET@ZIF-8) in the aqueous system. The engineered Escherichia coli (E. coli) expressing SAET was encapsulated into the imidazole framework structure of metal organic zeolite (ZIF-8). Subsequently, the obtained SAET@ZIF-8 was characterized, and the catalytic activity, reusability and storage stability were also investigated. Results showed that the morphology of the prepared SAET@ZIF-8 nanoparticles was basically the same as that of the standard ZIF-8 materials reported in literature, and the introduction of cells did not significantly change the morphology of ZIF-8. After repeated use for 7 times, SAET@ZIF-8 could still retain 67% of the initial catalytic activity. Maintained at room temperature for 4 days, 50% of the original catalytic activity of SAET@ZIF-8 could be retained, indicating that SAET@ZIF-8 has good stability for reuse and storage. When used in the biosynthesis of Ala-Gln, the final concentration of Ala-Gln reached 62.83 mmol/L (13.65 g/L) after 30 min, the yield reached 0.455 g/(L·min), and the conversion rate relative to glutamine was 62.83%. All these results suggested that the preparation of SAET@ZIF-8 is an efficient strategy for the biosynthesis of Ala-Gln.
Escherichia coli/genetics* ; Glutamine ; Zeolites/chemistry* ; Amino Acids

OBJECTIVE: To compare the clinical effects of pulpotomy with two kinds of calcium silicate materials, and to evaluate the formation of dentin bridge and pulp calcification after pulpotomy of adult permanent teeth. METHODS: Patients who visited the General Department of Peking University School and Hospital of Stomatology from November 2017 to September 2019 and planned for pulpotomy on permanent premolars and molars with carious exposed pulp were selected. They were randomly divided into two groups. Bioceramic putty material iRoot BP (iRoot group, n=22) and mineral trioxide aggregate MTA (MTA group, n=21) were used as pulp capping agents, respectively. The patients were recalled after one year and two years. The clinical efficacy, dentin bridge index (DBI) and pulp calcification index (PCI) were recorded. Blinding method was used for the patients and evaluators. RESULTS: There was no significant difference in gender, mean age, dentition and tooth position between the two groups (P>0.05). Seven cases were lost during the first year (4 cases in iRoot group and 3 cases in MTA group). In the iRoot group, 1 case had transient sensitivity at the time of 1-year follow-up. The cure rate of the two groups was 100% at the time of 2-year follow-up. The proportion of dentin bridge formation was 38.9% one year after operation, 55.6% two years after operation. The proportion of partial or even complete disappearance of root canal image was 5.6% before operation, 38.9% and 55.6% one and two years after operation, respectively. The difference was statistically significant by rank sum test (P < 0.05). There was no significant difference in dentin bridge formation and pulp calcification between the two groups (P < 0.05). DBI and PCI after operation was as the same as those before operation (44.4% cases of DBI and 25% cases of PCI) or gradually increased (55.6% cases of DBI and 75% cases of PCI). Spearman's nonparametric correlation analysis showed that age was positively correlated with preoperative pulp calcification index (PCI0, P < 0.05), but not with the dentin bridge index (DBI1, DBI2), pulp calcification index (PCI1, PCI2) and the degree of change (DBI2 vs. DBI1, PCI1 vs. PCI0, PCI2 vs. PCI0) 1-year and 2-year after operation (P>0.05). CONCLUSION According to this study, good clinical effects were obtained within 2-year after pulpotomy of adult permanent teeth with MTA and iRoot. In some cases, the root canal system had a tendency of calcification aggravation, and there was no statistical difference in the development of this trend between the two groups.
Humans ; Adult ; Pulpotomy/methods* ; X-Rays ; Calcium Compounds/therapeutic use* ; Dentition, Permanent ; Molar/surgery* ; Treatment Outcome ; Silicates/therapeutic use* ; Aluminum Compounds/therapeutic use* ; Oxides ; Drug Combinations ; Dental Pulp Capping

OBJECTIVE: To evaluate the clinical characteristics and effectiveness of pulpotomy in mature permanent teeth with bioceramic putty repairmen iRoot and mineral trioxide aggregate (MTA). METHODS: Pulpotomy was performed on mature permanent premolars and molars with carious exposures at the Department of General Dentistry of Peking University School and Hospital of Stomatology, from November 2017 to September 2019. The patients were randomly divided into 2 groups, Group iRoot (n=22) and Group MTA (n=21). In Group iRoot, bioceramic putty repairmen iRoot was used as pulp capping agent, while in Group MTA, mineral trioxide aggregate was used as pulp capping agent. All the patients had signed informed consent forms. The clinical efficacy was evaluated by clinical examinations (temperature and electrical activity test) and imaging examinations 3, 6, and 12 months after surgery. Blinding was used for the patients and evaluators, but due to the obvious differences in the properties of the two pulp capping agents, the blinding method was not used for the treatment provider (the attending physician). RESULTS: There was no significant difference in gender, average age, dentition and tooth position distribution between the two groups (P>0.05). In the study, 7 cases were lost to follow-up 12 months after operation (4 cases in Group iRoot, and 3 cases in Group MTA). One case in each of the two groups had transient sensitivity at the end of the 3-month follow-up, and the pulp vitality was normal at the end of the 6-month follow-up. One case in Group iRoot showed sensitivity at the end of the 12-month follow-up. The success rates of the two groups at the end of 12-month follow-up were 100%, and the cure rates were 94.4% (Group iRoot) and 100% (Group MTA), respectively, and the difference was not statistically significant (P>0.05). No cases in Group iRoot had obvious crown discoloration, while 3 cases in Group MTA had. CONCLUSION The clinical characteristics and effectiveness of pulpotomy in mature permanent teeth with bioceramic putty repairmen iRoot were similar with MTA. Bioceramic putty repairmen iRoot is an acceptable material when used in pulpotomy of mature permanent teeth. Because it is not easy to cause tooth discoloration after treatment and is convenient to operate, bioceramic putty repairmen iRoot has a better clinical application prospect.
Aluminum Compounds/therapeutic use* ; Calcium Compounds/therapeutic use* ; Drug Combinations ; Humans ; Oxides/therapeutic use* ; Pulpotomy ; Silicates/therapeutic use* ; Treatment Outcome

OBJECTIVE: To evaluate the efficacy of iRoot BP Plus, a novel bioceramic material, and mineral trioxide aggregate (MTA) by comparing the clinical and radiographic results of pulpotomy in human primary molars, and to find out the influence factor. METHODS: Children who had at least one primary molar diagnosed as pulpitis, and received pulpotomy in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology from January, 2017 to December, 2018 were searched by the selection criteria in the Electronic Medical Record Database of Peking University School and Hospital of Stomatology. The molars with the pulp capping agents were iRoot BP Plus or MTA were included, and the molars with other pulp capping agents were excluded. Molars using iRoot BP Plus were selected into the experimental group (iRoot BP Plus group). Molars using MTA were selected into the control group (MTA group) using propensity score matching model (1 ∶ 1), considering the gender, age, tooth position, the title of clinician, pulp status, restoration and length of follow-up as the potential influence factor. Basic information, the relevant medical records including symptoms, clinical and radiographic examination before and after operation, intraoperative information and follow up examination records were collected. The success rates were compared and the influence factors were analyzed respectively. RESULTS: The study included 132 children, 178 molars (89 molars from each group) and the mean follow-up time was (462±99) days by December, 2019. In the iRoot BP Plus group, 9 molars failed whilst 6 molars failed in MTA group. The success rate was 89.9% and 93.3%, respectively, showing no significant difference between the two groups. Through Cox proportional risk model analysis, the success rate of iRoot BP Plus was significantly lower when the pulp status was poor, while other factors including age, tooth position, title of clinician and restoration were not found to be associated with the clinical outcome. CONCLUSION Pulpotomy of human primary molars with iRoot BP Plus has the same effectiveness with MTA. The pulp status is the main factor that influences the outcome of iRoot BP Plus. Further studies with larger sample sizes and longer follow-up terms are needed.
Child ; Humans ; Pulpotomy/methods* ; Pulp Capping and Pulpectomy Agents ; Pemetrexed ; Silicates/therapeutic use* ; Aluminum Compounds/therapeutic use* ; Calcium Compounds ; Oxides ; Molar/surgery* ; Drug Combinations ; Treatment Outcome ; Tooth, Deciduous

Aims: This research was conducted to develop and characterize polyvinyl alcohol (PVA)/montmorillonite (MONT) clay incorporated with carvacrol (Carva) nanocomposite film as a potential material in wound dressing. Methodology and results: Organophilic MONT clay, which was initially modified from commercial MONT clay by cetyltrimethylammonium bromide (CTAB), was used in the polymerization process using PVA. The synthesized nanocomposites were visualized via transmission electron microscopy (TEM). The developed film (PVA/MONT/Carva nanocomposite film) was characterized via Fourier transform infrared (FTIR). The investigation on mechanical property and antimicrobial activity of the film was also performed. All nanocomposites are spherical, with a size of 92.8 ± 22.1 nm. The -OH stretch, C-H stretch, aromatic group, SiO stretch, and C-O from acetyl group were identified in the PVA/MONT/Carva nanocomposite films. During the chemical release test, carvacrol attained a plateau at 24 h, with a total release of 62.3%. This nanocomposite exhibited a severe detrimental influence on the growth of Gram-bacteria and yeasts, which represented a broad spectrum of antimicrobial agents. All test microorganisms showed approximately up to 82% reduction of microbial growth during the Hohenstein challenge test. Physically, the nanocomposite films were yellowish and apparent. The film was sturdy, flexible, elastic and consisted of excellent water holding capacity. Conclusion, significance and impact of study PVA/MONT/Carva nanocomposite film may have a useful potential to be merged in the pharmaceutical application, especially in wound dressing production.
Polyvinyl Alcohol ; Bentonite ; Wound Healing

PURPOSE: The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols.MATERIALS AND METHODS: Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, μSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests.RESULTS: The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05).CONCLUSION: Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.
Adhesives ; Aluminum Oxide ; Ceramics ; Clinical Protocols ; Dental Bonding ; Dental Restoration Repair ; Hydrofluoric Acid ; Microscopy, Electron, Scanning ; Polymers ; Shear Strength ; Silicon Dioxide

PURPOSE: The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS: 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and Mann-Whitney U tests (P<.05). RESULTS: Surface polishing procedures had significant effects on water absorption and solubility and surface microhardness of resin ceramics (P<.05). Group IV exhibited the lowest water absorption and the highest microhardness values (P<.05). Immersion periods had no effect on the microhardness of hybrid ceramic materials (P>.05). CONCLUSION: Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.
Absorption ; Aluminum Oxide ; Ceramics ; Computer-Aided Design ; Dental Polishing ; Diamond ; Immersion ; Rubber ; Silicon ; Silicones ; Solubility ; Water

PURPOSE: The aim of this study is to evaluate the effects of various primers on the microtensile bond strength (µTBS) of resin cements to cobalt-chromium (Co-Cr) dental casting alloy. MATERIALS AND METHODS: Four adhesive primers (Universal primer, Metal primer II, Alloy primer, and Metal/Zirconia primer) and two resin cements (Panavia F2.0, G-CEM LinkAce) were tested. One hundred fifty Co-Cr beams were prepared from Co-Cr ingots via casting (6 mm length × 1 mm width × 1 mm thick). The metal beams were randomly divided into ten groups according to the adhesive primers and resin cements used; the no-primer groups served as the control (n = 15). After sandblasting with aluminum oxide (125 µm grain), the metal and resin cements were bonded together using a silicone mold. Prior to testing, all metal-resin beams were examined under stereomicroscope, and subjected to the µTBS test. The mean value of each group was analyzed via one-way ANOVA with Tukey's test as post hoc (α = .05) using SPSS software. RESULTS: The mean µTBS of all groups was ranged from 20 to 28 MPa. There is no statistically significant difference between groups (P > .05). Mixed failure, which is the combination of adhesive and cohesive failures, is the most prevalent failure mode in both the Panavia F2.0 and G-Cem LinkAce groups. CONCLUSION: The µTBS of all tested groups are relatively high; however, the primers used in this study result in no favorable effect in the µTBS of Panavia F2.0 and G-Cem LinkAce resin cement to Co-Cr alloy.
Adhesives ; Alloys ; Aluminum Oxide ; Fungi ; Resin Cements ; Silicon ; Silicones

Increasing demands for esthetic dental treatment, zirconia, which has high mechanical and esthetic properties, had been applied more and more in clinics. Therefore, assessment of biocompatibility of zirconia is necessary. In this article, a review of in vivo studies of zirconia compatibility was performed. In vivo studies showed zirconia had great biocompatibility both on soft and hard tissue. Studies with various animals and patients reported high biocompatibility of zirconia. In terms of bone synthesis and bone adhesion, zirconia showed similar biocompatible properties to titanium. On the other hand, zirconia could be used as implant. For using as an implant, various methods of Hydroxyapatite (HA) coating had been suggested. Since HA coating on titanium implant showed some problems such as low bonding strength and degeneration of HA, HA-zirconia composite, HA-coated zirconia, and HA-zirconia functionally graded material (FGM) or intermediate layer of alumina had been proposed. These methods showed higher bonding strength and biocompatibility.
Aluminum Oxide ; Animals ; Durapatite ; Hand ; Humans ; Titanium

Ceramic articulation has gained popularity in total hip arthroplasty (THA); however, one of the most important concerns about the use of ceramic materials is the potential for breakage. Importantly, almost all ceramic fractures occur within the first six years after surgery. Here, we present a case report of a 52-year-old female patient who experienced an atraumatic ceramic head fracture at the 16th year after surgery. Key parameters that may be associated with ceramic head fracture are considered to be the use of a 28-mm head and high body mass index (BMI); the patient described here had a BMI of 34.3 kg/m2. Surgical treatment of the case included removal of the broken ceramic head and replacement with an alumina matrix composite ceramic head. At the 12th month follow-up visit, the patient was mobilized independently and could perform her daily activities. Ceramic head fracture after THA may occur even in late periods after surgery. For the treatment of fractures of ceramic material, the fractured component must be removed together with extensive soft tissue excision to ensure that no residual fragments are left behind.
Aluminum Oxide ; Arthroplasty ; Arthroplasty, Replacement, Hip ; Body Mass Index ; Ceramics ; Female ; Follow-Up Studies ; Head ; Hip ; Hip Prosthesis ; Humans ; Middle Aged