Why would toothbrushing make any difference?

How was the study done?

14 of the studies were conducted in ICUs

13 involved patients who needed to be on a ventilator

11 used an antiseptic rinse called chlorhexidine gluconate for all patients: those who underwent toothbrushing and those who didn't.

What were the findings?

What were the study's strengths and limitations?

How exactly can toothbrushing prevent hospital-acquired pneumonia?

How much does toothbrushing matter if you're not hospitalized?

Women's Champions League: Arsenal v Lyon Venue: Emirates Stadium Date: Saturday, 19 April Kick-off: 12:30 BST Coverage: Live radio commentary on BBC Radio 5 Live and text updates on the BBC Sport website and app For Arsenal and Lyon, Saturday's meeting in north London will be comfortably their biggest game of the season to date. That there is a significant reunion thrown into the mix will only amplify the sense of occasion. What is clear is that the first leg of the Women's Champions League semi-final presents an opportunity to put one foot in May's final. Arsenal, the only English side to have won the competition, are eyeing a first European crown since 2007. For Lyon, a record-extending ninth title is within sight. And in charge of masterminding a Lyon victory is a familiar face, with former Arsenal head coach Joe Montemurro returning to Emirates Stadium. The Australian is fondly remembered after winning two trophies during his three and a half years at Arsenal, but can Renee Slegers' free-scoring Gunners spoil his return? Montemurro arrived at Arsenal from Melbourne City in December 2017, tasked with turning around a slow start to the season which had led to the club parting company with Pedro Martinez Losa. The new boss took just three months to lift his first piece of silverware as Arsenal won the Women's League Cup, before he guided the team to their first Women's Super League title for seven years the following season. That achievement also secured a spot in the Women's Champions League for the first time since 2013-14. Arsenal went on to reach the quarter-finals in Europe, but they missed out on trophies during Montemurro's final two seasons and he chose to leave at the end of the 2020-21 campaign to spend more time with his family. Former Arsenal defender Jen Beattie, who played under Montemurro for two seasons, was full of praise for the Australian. "I loved his style of play, I loved his training, I loved his technical outlook on the game. He really simplified the game. And I loved his philosophy and his methodology," Beattie told BBC 5 Live Sport's Women's Football Weekly. "He was so easy to talk to. You could approach him about anything, you could talk about personal things, you can talk about football. "He will get the warmest welcome coming back. All the girls still there that worked under him understand that and the fans as well." During his tenure at Arsenal, which coincided with the emergence of a dominant Chelsea side, Montemurro won two trophies, reached four domestic cup finals, and twice guided Arsenal into the Women's Champions League. He returned to management with Juventus in June 2021 before succeeding Chelsea-bound Sonia Bompastor at Lyon in June 2024. Tasked with spoiling Montemurro's return is Slegers, who was appointed as Arsenal's permanent head coach in January 2025, following the departure of Jonas Eidevall last October. Eidevall, who led the side to a Champions League semi-final in 2023, left with Arsenal sixth in the WSL and reeling from a 5-2 defeat by Bayern Munich in their Champions League opener. Since then, Arsenal have won 22 of their 27 matches under Slegers, including a 13-match unbeaten run to begin her tenure. The Champions League provides their most realistic hope of silverware this season, and one area of improvement under Slegers has been Arsenal's attacking form. "There's a clear connection between Slegers and the players," former Arsenal defender Anita Asante told BBC Radio 5 Sports Extra. "She's shown she trusts what they can do on the pitch and allows them to do it. "They're more aggressive in that final third now and they're really clinical too." Under Slegers, Arsenal have scored: 80 goals in 27 matches, failing to score in just three games; at least four goals on 13 occasions, including an ongoing run of seven successive WSL home matches; 50 goals in 15 WSL games - in total, WSL leaders Chelsea have 49 goals from 18 matches in the competition. England striker Alessia Russo, who is expected to return from injury on Saturday, has found her best form under the Dutchwoman and is joint second in the Champions League individual standings with six goals. Assessing how Slegers' side compare to Eidevall's, Asante added: "It's direct, it's snappier, and it's also harder to defend [against]. "This is another feature of Slegers' [Arsenal]: having control in the opposition half, dictating the tempo, and making it difficult for the opposition to breathe." In Lyon, Arsenal are facing Women's Champions League royalty. The French side have won the competition a record eight times, including a run of five consecutive titles between 2016 and 2020, and reached the final on a further three occasions, most recently in 2024 when they lost to Barcelona. They have continued to thrive in Montemurro's first season in charge, beating Wolfsburg, Roma, and Galatasaray home and away to top Group A by nine points before defeating Bayern Munich 6-1 on aggregate to cruise into the last four for the 14th time in 18 Champions League campaigns. They've scored 25 goals and conceded just twice in Europe, and are the only unbeaten side left in the draw. Indeed, they've only lost once in all competitions in 2024-25, beaten in a penalty shootout by Reims in the last 32 of the Coupe de France. Lyon's squad includes France forward Kadidiatou Diani and Haitian midfielder Melchie Dumornay, who have shared nine goals and six assists in the Champions League this season, and 2018 Ballon d'Or winner Ada Hegerberg. Despite their opponents' form and personnel, Beattie has backed Arsenal to reach the final. "I think Lyon are there for the taking," Beattie said. "I have watched them a lot over the Champions League. I don't think they're the Lyon we've seen in previous seasons that dominate the European game. "I'm thinking Arsenal can take this one and to see them in the Champions League final will hopefully be absolutely epic. A home start will be so important [and] a good result. The Emirates will be massive." Asante said "whoever controls the midfield" will come out on top. Having watched Arsenal's 5-1 win over Leicester City on Tuesday, she believes they have the fluidity in attack to exploit Lyon's weaknesses. "Lyon do play quite often with attacking full-backs, very similar to Arsenal, but they're really scary in transition," Asante said. "Even though Lyon dismantled Bayern Munich, they showed weaknesses and if Arsenal can exploit them and catch them in moments when they lack concentration, they can absolutely hurt them. "If [Arsenal] perform how they did against Leicester, they definitely have a chance to dismantle Lyon because they were fluid in their moments, they found those connections, and they were clinical in attack when they created those goalscoring opportunities. "The challenge for them is stopping Lyon's threats because Dumornay, Diani, [Tabitha] Chawinga, Hederberg – these are frightening attacking players."