Impact of dental visiting patterns on oral health: A systematic review of longitudinal studies

AIM

To systematically review longitudinal studies investigating the impact of dental visiting patterns on oral health across the life course.

METHODS

Five databases (MEDLINE, Embase, Scopus, Web of Science, CINAHL) were searched up to March 2023. Results were screened based on eligibility criteria in a two-stage process: title and abstract, and full-text review. A backward search of reference lists and a forward search of citations of the included papers was also conducted. The quality of the included papers was assessed using the Newcastle-Ottawa Scale. Key study information was extracted and a narrative synthesis of the findings was performed.

RESULTS

Eleven papers from five longitudinal studies in five countries (Australia, Brazil, China, New Zealand, Sweden) met the inclusion criteria. Studies of moderate to high quality consistently reported that regular dental attendance was associated with having less dental caries experience, fewer missing teeth and better oral health-related quality of life. Inconsistent findings were observed for decayed teeth, and no association was found for periodontal condition.

CONCLUSIONS

This review highlights an association between regular dental visiting pattern and improved oral health, notably less dental caries experience and better oral health-related quality of life. Dental attendance emerges as an important predictor of oral health across the life course, underscoring the importance of routine dental care.

REGISTRATION INFORMATION

The PROSPERO registration number is CRD42023396380.

Unveiling synergism of polymyxin B with chloramphenicol derivatives against multidrug-resistant (MDR) Klebsiella pneumoniae

Polymyxins are last-line antibiotics against multidrug-resistant Klebsiella pneumoniae but using polymyxins alone may not be effective due to emerging resistance. A previous study found that combining polymyxin B with chloramphenicol effectively kills MDR K. pneumoniae, although the bone marrow toxicity of chloramphenicol is concerning. The aim of this study is to assess the antibacterial efficacy and cytotoxicity of polymyxin B when combined with chloramphenicol and its derivatives, namely thiamphenicol and florfenicol (reported to have lesser toxicity compared to chloramphenicol). The antibacterial activity was evaluated with antimicrobial susceptibility testing using broth microdilution and time-kill assays, while the cytotoxic effect on normal bone marrow cell line, HS-5 was evaluated using the MTT assay. All bacterial isolates tested were found to be susceptible to polymyxin B, but resistant to chloramphenicol, thiamphenicol, and florfenicol when used alone. The use of polymyxin B alone showed bacterial regrowth for all isolates at 24 h. The combination of polymyxin B and florfenicol demonstrated additive and synergistic effects against all isolates (≥ 2 log10 cfu ml-1 reduction) at 4 and 24 h, respectively, while the combination of polymyxin B and thiamphenicol resulted in synergistic killing at 24 h against ATCC BAA-2146. Furthermore, the combination of polymyxin B with florfenicol had the lowest cytotoxic effect on the HS-5 cells compared to polymyxin B combination with chloramphenicol and thiamphenicol. Overall, the combination of polymyxin B with florfenicol enhanced bacterial killing against MDR K. pneumoniae and exerted minimal cytotoxic effect on HS-5 cell line.

ToxR is a c-di-GMP binding protein that modulates surface-associated behaviour in Pseudomonas aeruginosa

Pseudomonas aeruginosa uses multiple protein regulators that work in tandem to control the production of a wide range of virulence factors and facilitate rapid adaptation to diverse environmental conditions. In this opportunistic pathogen, ToxR was known to positively regulate the production of the major virulence factor exotoxin A and now, through analysis of genetic changes between two sublines of P. aeruginosa PAO1 and functional complementation of swarming, we have identified a previously unknown role of ToxR in surface-associated motility in P. aeruginosa. Further analysis revealed that ToxR had an impact on swarming motility by regulating the Rhl quorum sensing system and subsequent production of rhamnolipid surfactants. Additionally, ToxR was found to tightly bind cyclic diguanylate (c-di-GMP) and negatively affect traits controlled by this second messenger including reducing biofilm formation and the expression of Psl and Pel exopolysaccharides, necessary for attachment and sessile communities matrix scaffolding, in P. aeruginosa. Moreover, a link between the post-transcriptional regulator RsmA and toxR expression via the alternative sigma factor PvdS, induced under iron-limiting conditions, is established. This study reveals the importance of ToxR in a sophisticated regulation of free-living and biofilm-associated lifestyles, appropriate for establishing acute or chronic P. aeruginosa infections.

Perceptions of childhood asthma and its control among Malays in Malaysia: a qualitative study

Children with poor asthma control have poor health outcomes. In Malaysia, the Malays have the highest asthma prevalence and poorest control compared to other ethnicities. We aimed to explore Malay children with asthma and their parents' perceptions on asthma and its control. We conducted focus group discussions (FGD) using a semi-structured interview guide. Interviews were audio-recorded, transcribed verbatim and analysed thematically. Sixteen children and parents (N = 32) participated. The perception of asthma was based on personal experience, cultural and religious beliefs, and there was mismatch between children and parents. Parents perceived mild symptoms as normal, some had poor practices, raising safety concerns as children were dependent on them for self-management. Conflicting religious opinions on inhaler use during Ramadhan caused confusion in practice. Parents perceived a lack of system support towards asthma care and asthma affected quality of life. Urgent intervention is needed to address misconceptions to improve asthma care in children.

Microplasma direct writing for site-selective surface functionalization of carbon microelectrodes

Carbon micro- and nanoelectrodes fabricated by carbon microelectromechanical systems (carbon MEMS) are increasingly used in various biosensors and supercapacitor applications. Surface modification of as-produced carbon electrodes with oxygen functional groups is sometimes necessary for biofunctionalization or to improve electrochemical properties. However, conventional surface treatment methods have a limited ability for selective targeting of parts of a surface area for surface modification without using complex photoresist masks. Here, we report microplasma direct writing as a simple, low-cost, and low-power technique for site-selective plasma patterning of carbon MEMS electrodes with oxygen functionalities. In microplasma direct writing, a high-voltage source generates a microplasma discharge between a microelectrode tip and a target surface held at atmospheric pressure. In our setup, water vapor acts as an ionic precursor for the carboxylation and hydroxylation of carbon surface atoms. Plasma direct writing increases the oxygen content of an SU-8-derived pyrolytic carbon surface from ~3 to 27% while reducing the carbon-to-oxygen ratio from 35 to 2.75. Specifically, a microplasma treatment increases the number of carbonyl, carboxylic, and hydroxyl functional groups with the largest increase observed for carboxylic functionalities. Furthermore, water microplasma direct writing improves the hydrophilicity and the electrochemical performance of carbon electrodes with a contact-angle change from ~90° to ~20°, a reduction in the anodic peak to cathodic peak separation from 0.5 V to 0.17 V, and a 5-fold increase in specific capacitance from 8.82 mF∙cm-2 to 46.64 mF∙cm-2. The plasma direct-writing technology provides an efficient and easy-to-implement method for the selective surface functionalization of carbon MEMS electrodes for electrochemical and biosensor applications.