We aimed to compare the antimicrobial efficacy of chlorhexidine (CHX) and sodium hypochlorite (NaOCl), two irrigants routinely used in root canal therapy of permanent teeth. Electronic databases, including PubMed, EMBASE, Web of Science, and Cochrane Library, were searched for randomized controlled trials published until March 2020. The meta-analysis of relative risk (RR) and standardized mean difference (SMD) was performed using a random-effect model with a 95% confidence interval (CI). Subgroup analysis was performed for culture and molecular methods of bacterial detection. The literature search yielded 2,110 records without duplicates. Eight studies were eligible for a systematic review. No significant differences in the incidence of samples with positive bacterial growth after irrigation (RR=1.003, 95% CI: 0.729-1.380, p=0.987) and mean bacterial number changes (SMD=0.311, 95% CI: -0.368-0.991, p=0.369) were observed between CHX and NaOCl in the culture and molecular subgroups. Heterogeneity in RR (I2=0%, p=0.673) was low among studies, while considerable heterogeneity was observed in the analysis of SMD (I2=76.336%, p=0.005). Our findings suggest that both CHX and NaOCl can reduce bacterial infections after irrigation, without any significant difference in antimicrobial efficacy between them. Although CHX and NaOCl showed similar efficacy, their molecular mechanisms were different. Therefore, they can be used as the main antibacterial root canal irrigants. However, our results were limited by inconsistencies among retrieved articles and a lack of clinically relevant outcomes. Further well-designed clinical studies are warranted to supplement our results.

We investigated the effects of bicarbonate on the growth of several different bacteria as well as its effects on biofilm formation and intracellular cAMP concentration in Pseudomonas aeruginosa. Biofilm formation was examined in 96-well plates, with or without bicarbonate. The cAMP production of bacteria was measured by a commercial assay kit. We found that NaHCO3 (100 mmol l-1) significantly inhibited, whereas NaCl (100 mmol l-1) did not influence the growth of planktonic bacteria. MIC and MBC measurements indicated that the effect of HCO3- is bacteriostatic rather than bactericidal. Moreover, NaHCO3 prevented biofilm formation as a function of concentration. Bicarbonate and alkalinization of external pH induced a significant increase in intracellular cAMP levels. In conclusion, HCO3- impedes the planktonic growth of different bacteria and impedes biofilm formation by P. aeruginosa that is associated with increased intracellular cAMP production. These findings suggest that aerosol inhalation therapy with HCO3- solutions may help improve respiratory hygiene in patients with cystic fibrosis and possibly other chronically infected lung diseases.

Menthol is often used as a cold-mimicking substance to allegedly enhance performance during physical activity, however menthol-induced activation of cold-defence responses during exercise can intensify heat accumulation in the body. This meta-analysis aimed at studying the effects of menthol on thermal perception and thermophysiological homeostasis during exercise. PubMed, EMBASE, Cochrane Library, and Google Scholar databases were searched until May 2020. Menthol caused cooler thermal sensation by weighted mean difference (WMD) of − 1.65 (95% CI, − 2.96 to − 0.33) and tended to improve thermal comfort (WMD = 1.42; 95% CI, − 0.13 to 2.96) during physical exercise. However, there was no meaningful difference in sweat production (WMD = − 24.10 ml; 95% CI, − 139.59 to 91.39 ml), deep body temperature (WMD = 0.02 °C; 95% CI, − 0.11 to 0.15 °C), and heart rate (WMD = 2.67 bpm; 95% CI − 0.74 to 6.09 bpm) between the treatment groups. Menthol improved the performance time in certain subgroups, which are discussed. Our findings suggest that different factors, viz., external application, warmer environment, and higher body mass index can improve menthol’s effects on endurance performance, however menthol does not compromise warmth-defence responses during exercise, thus it can be safely applied by athletes from the thermoregulation point of view.

Cystic fibrosis (CF) is a hereditary disease caused by mutations in the gene encoding an epithelial anion channel. In CF, Cl⁻ and HCO₃⁻ hyposecretion, together with mucin hypersecretion, leads to airway dehydration and production of viscous mucus. This habitat is ideal for colonization by pathogenic bacteria. We have recently demonstrated that HCO₃⁻ inhibits the growth and biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus when tested in laboratory culture media. Using the same bacteria our aim was to investigate the effects of HCO₃⁻ in artificial sputum medium (ASM), whose composition resembles CF mucus. Control ASM containing no NaHCO₃ was incubated in ambient air (pH 7.4 or 8.0). ASM containing NaHCO₃ (25 and 100 mM) was incubated in 5% CO₂ (pH 7.4 and 8.0, respectively). Viable P. aeruginosa and S. aureus cells were counted by colony-forming unit assay and flow cytometry after 6 h and 17 h of incubation. Biofilm formation was assessed after 48 h. The data show that HCO₃⁻ significantly decreased viable cell counts and biofilm formation in a concentration-dependent manner. These effects were due neither to extracellular alkalinization nor to altered osmolarity. These results show that HCO₃⁻ exerts direct antibacterial and antibiofilm effects on prevalent CF bacteria.

Purpose Controversy exists on whether a drug holiday is necessary for patients on antiresorptive medication for osteoporosis or bone metastasis and undergoing dental procedures to lower the risk of medication-related osteonecrosis of the jaw (MRONJ). This study evaluated the effects of discontinuing different antiresorptive regimens on MRONJ in these patients. Methods Publications from PubMed, EMBASE, Cochrane Library and EBSCO Open Dissertations were searched from inception to September 2023 following PRISMA guidelines, and the review was registered in PROSPERO. Eligibility criteria included clinical studies on the effects of continued and discontinued antiresorptive medications for osteoporosis or bone metastasis in patients undergoing dental procedures. The involved antiresorptive agents were oral bisphosphonates (BPs), intravenous (IV) BPs and denosumab (Dmab). Relative risk (RR) with 95% confidence interval (CI) was estimated using a random-effects model. Results Of the 2,590 records identified, six studies (n = 717) were included. Discontinued use of oral BPs had a lower MRONJ risk than discontinuation of IV BPs (RR = 0.05; 95% CI: 0.00–0.83) and continuation of IV BPs (RR = 0.03; 95% CI: 0.00–0.46). Continuing oral BPs also resulted in a lower MRONJ risk compared to both discontinuation and continuation of IV BPs, with RR = 0.04 (95% CI: 0.00–0.67) and RR = 0.03 (95% CI: 0.00–0.37), respectively. No significant difference was found between continuation and discontinuation of oral BPs, along with other comparisons. Conclusions A drug holiday may not be necessary before dental procedures for oral BPs. Temporary discontinuation of IV BPs or Dmab is also unlikely to reduce MRONJ risk compared to continued medication. Abstract Purpose Controversy exists on whether a drug holiday is necessary for patients on antiresorptive medication for osteoporosis or bone metastasis and undergoing dental procedures to lower the risk of medication-related osteonecrosis of the jaw (MRONJ). This study evaluated the effects of discontinuing different antiresorptive regimens on MRONJ in these patients. Methods Publications from PubMed, EMBASE, Cochrane Library and EBSCO Open Dissertations were searched from inception to September 2023 following PRISMA guidelines, and the review was registered in PROSPERO. Eligibility criteria included clinical studies on the effects of continued and discontinued antiresorptive medications for osteoporosis or bone metastasis in patients undergoing dental procedures. The involved antiresorptive agents were oral bisphosphonates (BPs), intravenous (IV) BPs and denosumab (Dmab). Relative risk (RR) with 95% confidence interval (CI) was estimated using a random-effects model. Results Of the 2,590 records identified, six studies (n = 717) were included. Discontinued use of oral BPs had a lower MRONJ risk than discontinuation of IV BPs (RR = 0.05; 95% CI: 0.00–0.83) and continuation of IV BPs (RR = 0.03; 95% CI: 0.00–0.46). Continuing oral BPs also resulted in a lower MRONJ risk compared to both discontinuation and continuation of IV BPs, with RR = 0.04 (95% CI: 0.00–0.67) and RR = 0.03 (95% CI: 0.00–0.37), respectively. No significant difference was found between continuation and discontinuation of oral BPs, along with other comparisons. Conclusions A drug holiday may not be necessary before dental procedures for oral BPs. Temporary discontinuation of IV BPs or Dmab is also unlikely to reduce MRONJ risk compared to continued medication.

The formation of Pseudomonas aeruginosa biofilms in cystic fibrosis (CF) is one of the most common causes of morbidity and mortality in CF patients. Cyclic di-GMP and cyclic AMP are second messengers regulating the bacterial lifestyle transition in response to environmental signals. We aimed to investigate the effects of extracellular pH and bicarbonate on intracellular c-di-GMP and cAMP levels, and on biofilm formation. P. aeruginosa was inoculated in a brain–heart infusion medium supplemented with 25 and 50 mM NaCl in ambient air (pH adjusted to 7.4 and 7.7 respectively), or with 25 and 50 mM NaHCO₃ in 5% CO₂ (pH 7.4 and 7.7). After 16 h incubation, c-di-GMP and cAMP were extracted and their concentrations determined. Biofilm formation was investigated using an xCelligence real-time cell analyzer and by crystal violet assay. Our results show that HCO₃⁻ exposure decreased c-di-GMP and increased cAMP levels in a dose-dependent manner. Biofilm formation was also reduced after 48 h exposure to HCO₃⁻. The reciprocal changes in second messenger concentrations were not influenced by changes in medium pH or osmolality. These findings indicate that HCO₃⁻ per se modulates the levels of c-di-GMP and cAMP, thereby inhibiting biofilm formation and promoting the planktonic lifestyle of the bacteria.