Close-up of bacteria found in the mouth which can cause halitosis or bad breath.
The Oral Microbiome Research Group is a multidisciplinary team of scientists, clinicians (dentists) and educationalists, investigating the immunological and vascular mechanisms by which oral bacteria regulate health and disease. Principal Investigators within the group have interests in hypertension, mouthwashes, neuroscience, dietetics and oral cancer; all relating to the oral microbiome. The approach is translational, with clinical trials are underway in human participants and with human tissue, as well as laboratory-based studies utilising metagenomics, physiological analysis, molecular biology, tissue culture and tissue engineering models. Clinical trials also involve research led by the dental team, in primary care dental clinics (PDSE), to offer a variety of health screening services at the dentists.


Recent publications and new advances

Appropriate clinical use of Chlorhexidine; a mouthwash that altersthe diversity of the oral microbiome, the acidity of the oral environment and bloodpressure via nitrate reducing bacteria.

Bescos R, Ashworth A, Cutler C. et al. Effects of Chlorhexidinemouthwash on the oral microbiome. SciRep 2020 10; 5254. 

Brookes ZLS, Bescos R, Belfield LA, Ali K, Roberts A. Currentuses of chlorhexidine for management of oral disease: a narrative review. JDent 2020, 103:103497. 

Read press release

Advising the general public on appropriate mouthwash use:

Discovering new mechanisms by which the oral microbiome and diet contribute to cardiovascular health

Ashworth A, Cutler C, Farnham G, Liddle L, Burleigh M, Rodiles A, Sillitti C, Kiernan M, Moore M, Hickson M, Easton C, Bescos R. Dietary intake of inorganic nitrate in vegetarians and omnivores and its impact on blood pressure, resting metabolic rate and the oral microbiome. Free Radic Biol Med 2019;138:63-72.

Shifting opinions from ‘killing’ bacteria to ‘balancing’ microbiological ecosystems.

The entero-salivary nitrate reducing pathway may be a causal mechanism linking oral and cardiovascular health, as oral bacteria converting nitrate to nitrite from green leafy vegetables produces nitric oxide that decreases blood pressure and maintains homeostasis.

Brookes ZLS, Belfield LA, Ashworth A,Casas-Agustench P, Raja M, Pollard AJ, Bescos R. Effects of chlorhexidinemouthwash on the oral microbiome. J Dent. 2021; 113:103768.

Peninsula Dental School advising general dentists in primary care how to become involved in dental research.

Brookes Z, Mills I, Witton R. et al. Top tips for incorporating research. Br Dent J 232, 427–429 (2022).

Translational research and clinical trials

Blood pressure screening in primary care within Peninsula Dental Social Enterprise

Improving access to care and developing integrated care systems at the dentists. These clinics are currently running for patients attending PDSE dental clinics in Devonport, offering blood pressure measurement by trial staff in areas of social deprivation, as well as offering other health checks including glucose, cholesterol, BMI, Qrisk and lifestyle assessment at the dentists. (Doble et al, 2023a: Doi: 10.3390/ijerph20064959). Our published work within these clinics has been highlighted by University and Plymouth media outlets, including a case study where detection of high blood pressure enables a patient to receive life saving treatment (Doble et al, 2023b; DOI: 10.1038/s41415-023-6546-6). 
Working with the Office of the Chief Dental Officer on commissioning of blood pressure screening at the dentists - making every contact count; our work spreads to other sites:

Oral health care packages in primary care dental practices

Leading on developing primary care research networks in dentistry.ENHANCE-D is a multicentre £2.8m national clinical trial, led by the University of Newcastle and funded by the National Institute of Health and Care Research (NIHR), being one of the largest clinical trials to be conducted in primary care dentistry. Plymouth is one of seven national hubs overseeing primary care dental practices to take providing ‘healthcare advice packages’ to patients that attend the dentists, with two practices/sites running within dental school clinics (PDSE) and support provided by the South West NIHR Clinical Research network (CRN).
Discovering new approaches to improving women’s health via oral health
Clinical trials are taking place in both primary and secondary care investigating the links between periodontal disease, the oral microbiome and pre-eclampsia, as part of an NIHR CRN cross-discipline collaboration with Obstetrics and Gynaecology, funded by the Trustees of Plymouth Hospitals.

Oral microbiome dysbiosis linked to hypertension

Leading on discovery science linking the oral microbiome and cardiovascular health.

Blood pressure clinics in PDSE primary care dental clinics, are also supporting clinical research trials investigating links between the oral microbiome / periodontal disease and cardiovascular disease in a dental primary care setting. Patients samples are used in Dr Bescos’ laboratory to facilitate oral microbiome metagenomic analysis and biochemical analysis of nitrate, nitrite and lactate in different oral niches. These projects have been expanded internationally to work with the University of Barcelona, University of Rwanda, and the University of Qatar Dental Schools.

Novel mouthwashes maintaining the oral microbiome and cardiovascular health

Discovering new mouthwashes.This clinical trial has successfully used propolis (a substance used to waterproof hives) as a novel mouthwash to improve gingival health and balance the oral microbiome, with resulting decreases in blood pressure. There have been interesting results so far and could be superior to existing products which focus on ‘killing’ bacteria; Read the press article.
Dr Zoe Brookes (lead FDI task team), Dr Raul Bescos Garcia and Amazon Doble have published with the FDI on the international recommendations for the use of  antimicrobial mouthwashes in oral care, through this IDJ Supplement. We were the first to study the oral microbiome with chlorhexidine in healthy people, and recommend mouthwash use only when the oral benefits outweigh risks, as killing all microbes (dysbiosis) can be harmful to both oral and systemic health. Read all six articles.

Pathogenic bacteria within the brain originating from the oral cavity

Improving cognitive health by discovering how oral bacteria get into the brain. These pilot clinical studies in collaboration with Plymouth Hospitals have determined that pathogenic oral bacteria may be present in cerebral abscesses of previously unknown source. Roy et al, 2023; 10.1016/j.jdent.2022.104366.
PDSE has also been a site for the Phase 2/3 trial on GAIN inhibitors which inhibit P Gingivalis entry into the brain of Alzheimer’s patients, which may ultimately improve the pathogenesis of disease.

Women’s health and the oral microbiome

The OMRG is also working with industrial partners on xerostomia, including OraleiveTM via the University R&D Solutions fund, to investigate the links between the oral microbiome and Women’s health, specifically menopause, seeking new interventions to manage dry mouth. A translational approach is used with both the case-finding PDSE dental clinics and laboratory based analysis of the oral microbiome and biochemical salivary markers. Watch this space for publications - preliminary data suggests that significant 'things happen' in the mouth during the menopause. 

Diet, the oral microbiome and cardiovascular health

Leading research on different type of diets and their impact on the oral microbiome and cardiovascular health. In this clinical trial, we investigated the effect of vegetarian diets on the composition of the oral microbiome
Current ongoing studies are measuring nitrate and nitrite in various vegetables and seaweeds to identify the most relevant dietary sources of these anions with potential prebiotic effect.
Promoting collaborative work between dietitians and dentists to address childhood body weight and oral health. This is a PhD project supported by the School of Health Professions to enhance dietary assessment and advice for children visiting PDSE dental clinics.  

Physical activity, the oral microbiome and cardiovascular health

Researcher taking a swab
Translational dentistry: our postgraduate students collecting samples in primary care, for laboratory-based analysis of biochemical markers and the microbiome in various oral niches
Oral Microbiome Research Group
Integrated health care in dentistry: measuring blood pressure and health screening at the dentist in a primary care setting

PhD studentships

Oral microbiome and hypertension

 Applicants are invited for a 3 year self-funded PhD, including bench fees, to analyse how oral microbiome dysbiosis may be relate to systemic hypertension. It is already known that the activity of nitrate-reducing oral bacteria (bacteria’s ability to convert nitrate into nitrite, maintaining lower blood pressure), is altered in people with hypertension and this mechanism will be explored using physiological methods, as a well as with metagenomic assessment of the microbiome. It will thus be both a laboratory based and clinical study working with people with hypertension.

Oral microbiome and novel mouthwashes

 Applicants are invited for a 3 year self-funded PhD, including bench fees, to analyse how novel mouthwashes alter the oral microbiome in the context of oral disease, namely periodontal disease. Thus far, our data suggests that certain mouthwashes may promote a detrimental dysbiotic environment. We are now testing novel antimicrobial agents and ‘natural’ probiotic compounds that have the potential to promote oral health, via the promotion of a diverse and balanced oral microbiome. It will be both a laboratory-based study, using metagenomics, and a clinical study working with patients for oral sampling, oral screening and physiological measurements.

Links between oral and systemic disease: primary care dental research

Applicants are invited for a 3 year self-funded PhD, including bench fees, to analyse the oral microbiome is altered in systemic diseases. We have supervisor expertise in the areas of Alzheimer’s disease, oral cancer, the pathophysiology of smoking, antibiotics and Women’s health (including pregnancy and pre-eclampsia), so could offer clinical, translational and laboratory based oral microbiome projects, or investigation of periodontal disease, in any of these fields, depending on the supervisor. We have recently set up health screening clinics at the dentists and thus have many unexplored opportunities to undertake primary care dental research at the University of Plymouth.

Dietetics services at the dentist

Applicants are invited for a 3 year self-funded PhD, including bench fees undertake research looking at the effect of food on oral health and the integration of the dietitian into the dental practice. The projects will combine a wide range of research approaches such as dietary questionnaires and dietary interventions, dental health measurements and laboratory analyses.
John Bull Building Tamar Science Park

Current collaborators, with thanks

Professor Mary Hickson, Professor in Dietetics, School of Health Professions, University of Plymouth, UK
Professor Chris Easton, University of West Scotland, UK
Professor Toni Gabaldon, Institute of Research in Biomedicine, Barcelona, Spain
Professor Robert Freeman, Obstetrics and Gynaecology Consultant, Univeisity of Plymouth teaching Hospital
Dr Holly Roy, Clinical Lecturer in Neurosurgery, Peninsula Medical School, University of Plymouth
Dr Ify Offiah, Obstetrics and Gynaecology Registrar, University of Bristol teaching Hospital
Dr Richard Holliday, Senior Lecturer and Consultant in Restorative Dentistry, University of Newcastle
Dr Agnes Gatarayiha, Deputy Dean of Dental School, University of Rwanda
Professor Kamran Ali, Professor of Oral Surgery, University of Qatar
Dr Philip Warburton, University of Plymouth (UK)
Professors Jon Lundberg and Eddie Weitzberg, Karolinska Institute (Sweden)
Dr Mia Burleigh, University of West Scotland (UK)
Professor Alex Mira and Dr Bob Rosier, FISABIO (Spain)
Dr Simone Porcelli, University of Pavia (Italy)
Dr Jose Lopez, University of Barcelona (Spain)
Dr Anna Oliveras, Hospital del Mar Research Institute (Spain)

We would like to thank the following organisations for funding University of Plymouth Oral Microbiome Research

Plymouth Institute of Health and Care Research

The Plymouth Institute of Health and Care Research (PIHR) is a thriving community that conducts adventurous world-leading research with the explicit purpose of improving the health and care of the populations we serve. 
Our work is grounded in the needs of the people of the South West and other rural, coastal, and deprived communities worldwide, but PIHR’s research has national and international reach and impact. 
Find out more about the work of PIHR
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