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Arthroplasty (London, England) Feb 2021Methyl methacrylate (MMA) is commonly used in the fields of dentistry and orthopaedic surgery. However, there remain concerns for the occupational hazards of MMA,... (Review)
Review
INTRODUCTION
Methyl methacrylate (MMA) is commonly used in the fields of dentistry and orthopaedic surgery. However, there remain concerns for the occupational hazards of MMA, particularly during pregnancy and breastfeeding.
METHODS
We performed a systematic review of studies on effects that MMA may have in pregnancy in the context of exposure during orthopaedic surgery and dentistry. Review articles, studies lacking statistical data, single case reports and other evidence level V studies were excluded.
RESULTS
Nine studies were included. One basic science study demonstrated an increase in neuronal cell lysis and shrunken cell bodies when neocortical neurons were exposed to MMA monomer. Three animal studies exposed pregnant rodents to MMA via intraperitoneal injection or inhalation. Exposed fetuses in two studies had an increase in gross abnormalities such as hemangiomas, while there was no increase in teratologic effects in the third study. In dental workers exposed to MMA, two retrospective cohort studies did not find a statistically significant increase in birth defects or miscarriage. After exposure to MMA during total joint arthroplasty, two studies found that MMA levels were undetectable in the mothers' serum or breast milk. One study measuring the airborne levels of MMA during simulated joint arthroplasty found that concentrations never exceeded 1% of the recommended limit set forth by the Occupational Safety and Health Administration (OSHA).
CONCLUSIONS
Potential teratologic effects of MMA cannot be excluded by existing evidence. However, the typical MMA exposure levels for dental and orthopaedic personnel appear to be substantially less than currently proposed exposure limits.
PubMed: 35236460
DOI: 10.1186/s42836-020-00059-z -
Methods and Protocols Jan 2022The most used types of retention of implant-supported prostheses are screw-retained or cement-retained restorations. The advantages and disadvantages of both have been... (Review)
Review
BACKGROUND
The most used types of retention of implant-supported prostheses are screw-retained or cement-retained restorations. The advantages and disadvantages of both have been identified by various authors over the years. However, cement-retained implant crowns and fixed partial dentures are among the most used types of restorations in implant prostheses, due to their aesthetic and clinical advantages. When cemented prostheses are made on implants, the problem of cement residues is important and often associated with biological implant pathologies. The objective of this research was to establish to what extent the techniques to reduce excess cement really affect the volume of cement residues.
MATERIALS AND METHODS
This review was written following the PRISMA statement; a detailed search was carried out in three different electronic databases-PubMed, Scopus, and Cochrane Library. The inclusion criteria were prospective clinical studies, with at least 10 participants per group, and with at least 6 months of the follow-up period.
RESULTS
There have been many proposals for techniques supposed to reduce the amount of excess cement in the peri-implant sulcus and on the prosthetic components, but of these, which are exceptional in their in vitro capabilities, very few have been clinically validated, and this represents the real limitation and a great lack of knowledge regarding this topic. Three articles met the inclusion criteria, which were analyzed and compared, to obtain the information necessary for the purposes of the systematic review.
DISCUSSION
Extraoral cementation can reduce the excess cement, which, after a normal excess removal procedure, is, nevertheless, of such size that it does not affect the possibility of peri-implant pathologies developing. All these studies concluded that a small amount of cement residue is found in the gingival sulcus, and using eugenol-free oxide cements, the residues were only deposited on the metal surfaces, with a better peri-implant tissues health.
CONCLUSION
Despite the limitations of this study, it was possible to carefully analyze these characteristics and obtain valuable suggestions for daily clinical practice. Resinous cements are considered, due to the free monomers present in them, toxic for the soft tissues. The provisional zinc-oxide cements, also eugenol-free, represent the ideal choice. The different grades of retentive forces provided by these cements do not seem to have clinical effects on the decementation of restorations.
PubMed: 35076562
DOI: 10.3390/mps5010009 -
Bioengineering (Basel, Switzerland) Jan 2022Three-dimensional (3D) resin medical-dental devices have been increasingly used in recent years after the emergence of digital technologies. In Orthodontics, therapies... (Review)
Review
Three-dimensional (3D) resin medical-dental devices have been increasingly used in recent years after the emergence of digital technologies. In Orthodontics, therapies with aligners have gained popularity, mainly due to the aggressive promotion policies developed by the industry. However, their systemic effects are largely unknown, with few studies evaluating the systemic toxicity of these materials. The release of bisphenol A and other residual monomers have cytotoxic, genotoxic, and estrogenic effects. This systematic review aims to analyze the release of toxic substances from 3D resins used in Orthodontics and their toxic systemic effects systematically. The PICO question asked was, "Does the use of 3D resins in orthodontic devices induce cytotoxic effects or changes in estrogen levels?". The search was carried out in several databases and according to PRISMA guidelines. In vitro, in vivo, and clinical studies were included. The in vitro studies' risk of bias was assessed using the guidelines for the reporting of pre-clinical studies on dental materials by Faggion Jr. For the in vivo studies, the SYRCLE risk of bias tool was used, and for the clinical studies, the Cochrane tool. A total of 400 articles retrieved from the databases were initially scrutinized. Fourteen articles were included for qualitative analysis. The risk of bias was considered medium to high. Cytotoxic effects or estrogen levels cannot be confirmed based on the limited preliminary evidence given by in vitro studies. Evidence of the release of bisphenol A and other monomers from 3D resin devices, either in vitro or clinical studies, remains ambiguous. The few robust results in the current literature demonstrate the absolute need for further studies, especially given the possible implications for the young patient's fertility, which constitutes one of the largest groups of patients using these orthodontic devices.
PubMed: 35049724
DOI: 10.3390/bioengineering9010015 -
Restorative Dentistry & Endodontics Nov 2021The purpose of this systematic review was to collect and discuss the technique of adhesive systems application on dentin substrate under electric current.
OBJECTIVES
The purpose of this systematic review was to collect and discuss the technique of adhesive systems application on dentin substrate under electric current.
MATERIALS AND METHODS
The first search strategy was based on data available at PubMed, LILACS, Scielo, Scopus, and Cochrane Library, using a combination of descriptors such as "dentin bond agents OR adhesive system AND electric current OR electrobond" or "dentin bonding agents OR dentin bonding agent application OR adhesive system AND electric current OR electrobond", with no limit regarding the publication year. The second search strategy was based on the articles' references found previously. An additional search strategy was applied that concerned the proposed theme in the SBU-UNICAMP (Unicamp's Library System Institutional Repository).
RESULTS
Twelve studies published between 2006 and 2020 were found. The analyses of the selected studies showed that the use of electric current during adhesive systems application on dentin, whether conventional or self-conditioning, increases resinous monomer infiltration in the dentin substrate, which improves the hybridization processes and the bond strength of the restorative material to dentin.
CONCLUSIONS
Despite the favorable results related to the use of this technique, there is still no specific protocol for the application of adhesive systems under electric current.
PubMed: 34909419
DOI: 10.5395/rde.2021.46.e55 -
Systematic Reviews Aug 2021Sarcomas are a rare and heterogeneous group of tumors originating from mesenchymal or connective tissue. They represent less than 1% of all adult cancers. The etiology... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Sarcomas are a rare and heterogeneous group of tumors originating from mesenchymal or connective tissue. They represent less than 1% of all adult cancers. The etiology and epidemiology of sarcomas remain understudied and poorly understood. The main objective of our study was to systematically assess the association between various occupational exposures and risk of sarcomas.
METHODS
We performed a systematic literature search using the PubMed, Scopus, EMBASE and Cochrane databases to identify relevant cohort and case-control studies. A meta-analysis method was applied on the incidence and mortality outcomes where the estimate with 95% confidence interval (CI) was obtained.
RESULTS
We included a total of 50 publications in our systematic review and 35 in meta-analysis. For exposures to phenoxy herbicides and chlorophenols, the pooled odds ratio (OR) for sarcoma was 1.85 (95% CI: 1.22, 2.82), based on 16 studies with 2254 participants, while the pooled standardized mortality ratio was 40.93 (95% CI 2.19, 765.90), based on 4 cohort studies with 59,289 participants. For exposure to vinyl chloride monomers the pooled risk ratios for angiosarcoma of the liver and other STS were 19.23 (95% CI 2.03, 182.46) and 2.23 (95 CI 1.55, 3.22) respectively based on 3 cohort studies with 12,816 participants. Exposure to dioxins was associated with an increased STS mortality; the pooled standardized mortality ratio was 2.56 (95% CI 1.60, 4.10) based on 4 cohort studies with 30,797 participants. Finally, woodworking occupation was associated with an increased risk of STS with the pooled OR of 2.16 (95% CI 1.39, 3.36).
CONCLUSIONS
Our findings suggest a positive association between higher exposure to dioxins and increased mortality from STS, between cumulative exposure to vinyl chloride monomers and increased mortality from angiosarcoma of the liver and STS, and between woodworking occupation and STS incidence. These findings were all statistically significant.
Topics: Adult; Cohort Studies; Humans; Incidence; Occupational Diseases; Occupational Exposure; Sarcoma
PubMed: 34389054
DOI: 10.1186/s13643-021-01769-4 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Mar 2021Cyanobacteria is one of the promising microbial chassis in synthetic biology, which serves as a typical host for light-driven production. With the gradual depletion of...
Cyanobacteria is one of the promising microbial chassis in synthetic biology, which serves as a typical host for light-driven production. With the gradual depletion of fossil resources and intensification of global warming, the research on cyanobacterial cell factory using CO2 as carbon resource is ushering in a new wave. For a long time, research focus on cyanobacterial cell factory has mainly been the production of energy products, such as liquid fuels and hydrogen. One of the critical bottlenecks occurring in cyanobacterial cell factory is the poor economic performance, which is mainly caused by the inherent inefficiency of cyanobacteria. The problem is particularly prominent for these extremely cost-sensitive energy products. As an indispensable basis for modern industry, polymer monomers belong to the bulk chemicals with high added value. Therefore, increasing attention has been focused on polymer monomers which are superior in overcoming the economic barrier in commercialization of cyanobacterial cell factories. Here, we systematically review the progress on the production of polymer monomers using cyanobacteria, including the strategies for improving production, and the related technologies for the application of this important microbial cell factory. Finally, we summarize several issues in cyanobacterial synthetic biology and proposed future developing trends in this field.
Topics: Cyanobacteria; Macromolecular Substances; Polymers; Synthetic Biology
PubMed: 33783165
DOI: 10.13345/j.cjb.200637 -
Journal of Ethnopharmacology Apr 2021Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19), a highly pathogenic virus that has spread rapidly...
ETHNOPHARMACOLOGICAL RELEVANCE
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19), a highly pathogenic virus that has spread rapidly across the entire world. There is a critical need to develop safe and effective drugs, especially broad-spectrum antiviral and organ protection agents in order to treat and prevent this dangerous disease. It is possible that Chinese herbal medicine may play an essential role in the treatment of patients with SARS-CoV-2 infection.
AIM OF THE REVIEW
We aim to review the use of Chinese herbal medicine in the treatment of COVID-19 both in vitro and in clinical practice. Our goal was to provide a better understanding of the potential therapeutic effects of Chinese herbal medicine and to establish a "Chinese protocol" for the treatment of COVID-19.
MATERIALS AND METHODS
We systematically reviewed published research relating to traditional Chinese herbal medicines and the treatment of SARS-CoV-2 from inception to the 6 January 2021 by screening a range of digital databases (Web of Science, bioRxiv, medRxiv, China National Knowledge Infrastructure, X-MOL, Wanfang Data, Google Scholar, PubMed, Elsevier, and other resources) and public platforms relating to the management of clinical trials. We included the active ingredients of Chinese herbal medicines, monomer preparations, crude extracts, and formulas for the treatment of COVID-19.
RESULTS
In mainland China, a range of Chinese herbal medicines have been recognized as very promising anti-SARS-CoV-2 agents, including active ingredients (quercetagetin, osajin, tetrandrine, proscillaridin A, and dihydromyricetin), monomer preparations (xiyanping injection, matrine-sodium chloride injection, diammonium glycyrrhizinate enteric-coated capsules, and sodium aescinate injection), crude extracts (Scutellariae Radix extract and garlic essential oil), and formulas (Qingfei Paidu decoction, Lianhuaqingwen capsules, and Pudilan Xiaoyan oral liquid). All these agents have potential activity against SARS-CoV-2 and have attracted significant attention due to their activities both in vitro and in clinical practice.
CONCLUSIONS
As a key component of the COVID-19 treatment regimen, Chinese herbal medicines have played an irreplaceable role in the treatment of SARS-CoV-2 infection. The "Chinese protocol" has already demonstrated clear clinical importance. The use of Chinese herbal medicines that are capable of inhibiting SARS-Cov-2 infection may help to address this immediate unmet clinical need and may be attractive to other countries that are also seeking new options for effective COVID-19 treatment. Our analyses suggest that countries outside of China should also consider protocols involving Chinese herbal medicines combat this fast-spreading viral infection.
Topics: Animals; Drugs, Chinese Herbal; Humans; Medicine, Chinese Traditional; SARS-CoV-2; COVID-19 Drug Treatment
PubMed: 33485973
DOI: 10.1016/j.jep.2021.113869 -
Dental and Medical Problems 2020At present, new acrylic plastic technologies are being developed in dentistry. Although this kind of material has been used for dental prostheses for over 80 years, it... (Review)
Review
At present, new acrylic plastic technologies are being developed in dentistry. Although this kind of material has been used for dental prostheses for over 80 years, it has been produced in the form of disks with the computer-aided design/computer-aided manufacturing (CAD/CAM) technology for over 15 years. The purpose of the article was to collect information from the literature on acrylic materials processed through the milling technology (CAD/CAM). The publicly available databases PubMed, Google Scholar and Scopus were searched using the key word "acrylic resins, CAD/CAM". All articles describing the application and testing of CAD/CAM disks were selected. Duplicate articles were removed. More than 100 articles that described the use of materials machined using the milling equipment were found. These included works comparing the mechanical properties, biocompatibility and clinical use of the materials. After the initial selection, 36 papers on this subject were included in this review. The number of studies on the processing of acrylic materials with the use of the CAD/CAM technology has been increasing worldwide. Since such materials have better mechanical properties, no polymerization shrinkage occurs during processing, the amount of residual monomer material is very low and they have better color stability than self-curing materials.
Topics: Acrylic Resins; Computer-Aided Design; Dental Materials; Humans; Materials Testing; Polymethyl Methacrylate
PubMed: 33444491
DOI: 10.17219/dmp/124697 -
Maedica Jun 2020The aim of this study was to find the most effective surface preparation methods to enhance the bond strength between the composite resin and surface remaining from...
The Effect of Mechanical and Chemical Surface Preparation Methods on the Bond Strength in Repairing the Surface of Metal-Ceramic Crowns with Composite Resin: a Systematic Review and Meta-Analysis.
The aim of this study was to find the most effective surface preparation methods to enhance the bond strength between the composite resin and surface remaining from ceramic fracture. In this systematic review and meta-analysis, 39 studies were examined. The information related to the studies was extracted and categorized based on the type of the substrate material and applying or not applying thermal cycles (p<0.05). In the meta-analysis of substrate metal-ceramic samples without aging, application of air abrasion resulted in a significant increase of the bond strength to composite resin when using chemical compounds of the group without the mentioned functional monomers. Application of mechanical and chemical surface preparation methods can result in enhanced bond strength of the composite to the substrate material, which depends on the type of substrate material.
PubMed: 32952686
DOI: 10.26574/maedica.2020.15.2.206 -
Materials (Basel, Switzerland) Apr 2020Use of thermoplastic material in orthodontics, either as aligner or as retainer appliances, is common practice and is likely to increase in the years to come. However,... (Review)
Review
Safety Considerations for Thermoplastic-Type Appliances Used as Orthodontic Aligners or Retainers. A Systematic Review and Meta-Analysis of Clinical and In-Vitro Research.
Use of thermoplastic material in orthodontics, either as aligner or as retainer appliances, is common practice and is likely to increase in the years to come. However, no systematic assessment on safety considerations of these adjuncts has been implemented up to date. The aim of this systematic review was to collectively appraise the existing evidence from both clinical and laboratory studies, on whether these appliances are associated with any estrogenic/cytotoxic effects or bisphenol-A (BPA) and monomer leaching. Eight electronic databases were searched with no limits in December 22, 2019, for published and unpublished research. Eligibility criteria comprised of studies of any design, describing use of any type of thermoplastic aligner. Study selection, data extraction and risk of bias (RoB) assessment was done independently, either in duplicate or confirmed by a second reviewer. Random effects meta-analyses of weighted mean differences (WMD) with associated 95% Confidence Intervals (CIs) were planned. Quality of the evidence was evaluated with Grading of Recommendations Assessment, Development and Evaluation (GRADE). A total of 58 articles were initially identified, while 5 were included in qualitative synthesis and 2 of those contributed to the quantitative syntheses. Four studies were in-vitro, while one was a randomized controlled trial; all assessed some type of orthodontic aligner or retainer, either as-received or retrieved. Risk of bias recordings ranged between unclear and high for all studies. Proliferation induction capacity of thermoplastic appliances' eluents on MCF-7 cells failed to be confirmed compared to beta-estradiol (2 studies: 5% /, WMD: -182.08; 95% CI: -198.83, -165.33; -value < 0.001; and 20% /, WMD: -184.53; 95% CI: -206.17, -162.88; -value < 0.001). No cytotoxic activity was detected as well. In addition, although evidence from in-vitro studies was indicative of no traceable detection of BPA or other monomers, the findings from a single clinical trial were allied to increased levels of BPA in whole stimulated saliva, after up to 30 days of thermoplastic retainer usage, compared to standard Hawley retainer. The quality of the evidence overall was low to medium. Current data from in-vitro research are indicative of an absence of an estrogenic or cytotoxic effect of thermoplastic aligners or retainers. Regarding BPA or monomer release, evidence from clinical and laboratory studies appear inconsistent.
PubMed: 32295303
DOI: 10.3390/ma13081843