You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
in the previous issue of critical care , gu and colleagues   report the results of a systematic review and meta - analysis of oral hygiene with and without a toothbrush on ventilator - associated pneumonia ( vap ) . over the past two decades
an increasing body of data has demonstrated that poor oral hygiene increases the incidence of pneumonia in community , residential , hospitalised and critically ill individuals .
dental plaque serves as a reservoir for microorganisms associated with pulmonary infection and these potential respiratory pathogens have been shown to rapidly colonise plaque in mechanically ventilated critically ill patients .
attention to oral hygiene is recognised as an important component of care , which reduces vap ; however , there is substantial variability in how this is performed .
decolonisation strategies with oral antiseptics such as chlorhexidine or topical antibiotics decrease vap and are included in the european care bundle for prevention of vap .
provision of oral hygiene may include any combination of foam swabs , manual or electric toothbrushes , moisturisers , toothpaste , topical antibiotics , and oral antiseptics .
however , it is unclear which elements or combinations are most effective at improving oral cleanliness .
healthy individuals and self - caring patients normally clean their oral cavity with the use of a toothbrush as dental plaque , an archetypal biofilm , can only effectively be removed by mechanical disruption .
healthcare professionals have made the assumption that this would also represent the most effective measure for controlling plaque in mechanically ventilated patients , thereby reducing the burden of respiratory pathogens that could cause vap .
gu and colleagues   explored the data supporting this assumption by undertaking a systematic review and meta - analysis of oral hygiene with and with - out a toothbrush on vap .
four randomised clinical trials with 828 patients were identified that met the inclusion criteria . in this analysis
, toothbrushing did not reduce the incidence of vap , critical care mortality or length of stay , antibiotic administration or mechanical ventilation - free days .
gu and colleagues suggest that these results be cautiously interpreted and that well - designed large randomised clinical trials are urgently required to adequately address this matter .
the question remains why a method that effectively disrupts plaque subsequently fails to demonstrate any benefit in this patient population ?
vap is a common infection in critical care and leads to increased mortality , length of stay and cost .
the magnitude of attributable mortality is controversial , with recent estimates of 5 to 10% much lower than historical values .
establishing a diagnosis of vap in a mechanically ventilated patient is far more complex than it is for an individual presenting with community - acquired pneumonia and agreement amongst clinicians is poor .
it is perhaps not surprising that the small number of studies in the current meta - analysis , which used vap as the primary outcome measure , failed to show a reduction when toothbrushing was used .
a more robust outcome measure for studies that aim to improve oral hygiene by disrupting dental plaque would be to measure plaque ( and gingival ) scores in patients . unless a reduction in plaque scores can be demonstrated by the intervention under investigation one could
not , on the basis of biological plausibility , anticipate any effect on vap rates .
unfortunately , unlike the dental literature where plaque and gingival scoring is commonplace , this is rarely performed in critically ill patients .
this is most likely because plaque scoring necessitates a degree of expertise not present in many critical care healthcare workers and requires a calibration exercise if more than one scorer is used .
most observational studies , including a recent report by needleman and colleagues , that record plaque scores throughout the period of intubation demonstrate an increase over time . in the four studies included in the meta - analysis , none measured plaque scores as an outcome measure of toothbrushing .
it is therefore difficult to know if the failure of toothbrushing to reduce vap in these studies was due to this procedure not being performed adequately ( no reduction in plaque scores ) or plaque removal itself does not alter the incidence of vap .
in contrast , one study reviewed by gu and colleagues , which was excluded from the meta - analysis because it did not measure vap , compared the use of an electric toothbrush with a foam swab for removal of plaque and potential respiratory pathogens . both interventions were undertaken four times a day and all patients received 0.2% chlorhexidine at the same time .
the use of an electric toothbrush significantly reduced plaque scores compared to the foam swab at day 5 .
there was also a significant reduction in the mean counts of viable bacteria with the powered toothbrush .
it is worth noting that in this study , and despite the toothbrush being a more effective measure of plaque removal , use of the foam swab was also associated with a significant reduction in plaque by day 5 .
the optimal package of care for improving oral hygiene in the critically ill has not been adequately defined and some elements may be counterproductive .
sodium lauryl sulphate is used as a foaming agent in toothpaste but forms inactive low solubility salts with chlorhexidine .
toothpaste must be thoroughly removed prior to chlorhexidine use to prevent inactivation , or a non - foaming toothpaste used instead .
chlorhexidine may be a less effective antiseptic in vitro than other agents such as essential oils or triclosan - based products but is efficacious in vivo because of a property called substantivity .
the drug binds to clean oral surfaces and is then released over time mediating its antimicrobial effect .
chlorhexidine thus works largely by inhibiting the re - accumulation of dental plaque   following mechanical cleaning .
lorente and colleagues performed a single centre randomised clinical trial involving treatment with 0.12% chlorhexidine with manual toothbrushing and standard care . in total , 436 patients were enrolled in the study representing more than half of those included in the meta - analysis .
no significant difference was observed between groups in the incidence of the primary outcome measure vap .
importantly , toothbrushing was performed after the administration of chlorhexidine in this study , making this a less effective therapy than if the antiseptic had followed brushing .
thus , chlorhexidine may be used in concentrations from 0.12% to 2% and comes as a solution , gel or paste .
alternative antiseptics frequently used in dentistry , such as essential oils or triclosan formulations , might provide more effective plaque control .
tooth - brushes may be manual or electric and come with brushes of different sizes or bristle hardness , all of which may influence plaque disruption . improving oral hygiene
ideally , further studies exploring the optimal package of care for improving oral cleanliness should be undertaken before planning larger more expensive trials that have outcome measures such as vap , mortality or length of stay . powering studies for unambiguous endpoints such as mortality are preferable to those prone to bias , such as vap , but require far larger numbers of patients . defining what represents optimal oral care requires a greater understanding of the pathophysiology of the oral cavity , dental plaque , biofilm biology and the oral microbiome , and is dependent on effective collaboration between clinicians from critical care and dentistry .
mpw has sat on an advisory board for bard and merck and has received grant support from nischr .
he received royalties from wiley - blackwell publishing , and has received travel accommodations from isicem brussels , british thoracic society and eli lilly .
dww has previously received research support relating to oral and respiratory care from sage , glaxosmithkline , oraldent , covidien , and philips sonicare .
marc j bonten , professor of molecular epidemiology of infectious diseases , university medical centre , utrecht , netherlands , for critical reading of the manuscript .
improving the quality of oral hygiene is recognised as an important counter measure for reducing the incidence of ventilator - associated pneumonia amongst critically ill patients . 
 toothbrushing physically disrupts the dental plaque that acts as a reservoir for pulmonary infection and therefore has the potential to reduce the incidence of ventilator - associated pneumonia . 
 gu and colleagues performed a systematic review and meta - analysis of oral hygiene with and without a toothbrush and found no difference in the incidence of pneumonia in mechanically ventilated patients . 
 the diagnosis of ventilator - associated pneumonia is prone to bias and future studies of oral care interventions should focus on measures of oral cleanliness such as plaque and gingival scores . 
 once the optimal strategy for oral hygiene is defined in the critically ill , larger studies focussing on ventilator - associated pneumonia or mortality can be conducted .