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Sugar and tooth decay – is it ‘too much’ or ‘too often’?


Key facts

Type of research degree
Application deadline
Ongoing deadline
Country eligibility
International (open to all nationalities, including the UK)
Dr Thuy Do and Dr David Head
Additional supervisors
Professor Philip Marsh
School of Dentistry
<h2 class="heading hide-accessible">Summary</h2>

Understanding the relationship between sugar and health is a major Government priority. The link between sugar and caries is known, but it is not clear what is most important: the frequency of sugar intake or the total amount of sugar eaten. Existing advice favours the over-riding importance of frequency of sugar intake. This has been challenged recently by surveys of diet and decayed teeth in &gt;1,500 participants, which suggest a stronger link exists between caries and the total amount of dietary sugar. This must be addressed if the best guidance is to be given to parents, carers and children. We aim to determine which is most important (frequency or total sugar) in enhancing the growth of acid-producing plaque bacteria, and what factors may mitigate the effects. This will lead into more focused, better designed clinical studies that will help shape dietary advice to minimise caries risk in children.

<h2 class="heading hide-accessible">Full description</h2>

<p>We will use laboratory experiments and computational modelling to reveal the combinations of total sugar intake and frequency of intake that have the best and worst effects in promoting the growth of acid-producing or beneficial bacteria over many weeks. This will allow us to design the most effective clinical studies to confirm what really matters in terms of dietary sugars and childhood caries, speeding up the process from theory to practice.</p> <p>Thus, we will:</p> <ul> <li>Grow communities of plaque bacteria and systemically vary the frequency and total amount of sugar supplied to them with and without fluoride. We will monitor the effects of these combinations on the bacterial community as well as the amount of acid generated and compare both against conditions known to initiate tooth decay. We will also determine if beneficial bacteria (probiotics) or other agents that affect the microbial ecology can influence the outcome.</li> <li>The limited parameter sampling and durations achievable in the experiments will be mitigated by the use of a computational plaque model being developed in collaboration with Dr Head (Computing), preliminary results for which suggest a comparable role for both frequency and total sugar intake. Once calibrated to the experiments, this in silico model will provide a unified, long-time picture of the dietary risk factors for childhood caries.</li> </ul> <p>We will identify high risk factors that should be avoided, and provide bounds on the frequency and/or amount of sugar that we expect to reduce the risk of caries. This will be used to inform the design of pilot studies in children attending the Leeds Dental Institute, in collaboration with experts in Paediatric Dentistry and Dental Public Health. This will also be an important experimental project in an ongoing cross-Faculty collaboration that promises to deliver a powerful future technology for oral healthcare research.</p>

<h2 class="heading">How to apply</h2>

<p>Applications can be made at any time. To apply for this project applicants should complete a<a href=""> Faculty Application Form</a> and send this alongside a full academic CV, degree transcripts (or marks so far if still studying) and degree certificates to the Faculty Graduate School <a href=""></a>.</p> <p>We also require 2 academic references to support your application. Please ask your referees to send these <a href="">references</a> on your behalf, directly to&nbsp;<a href=""></a></p> <p>If you have already applied for other projects using the Faculty Application Form this academic session you do not need to complete this form again. Instead you should email&nbsp;<a href=""></a> to inform us you would like to be considered for this project.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

A degree in biological sciences, dentistry, medicine, midwifery, nursing, psychology or a good honours degree in a subject relevant to the research topic. A Masters degree in a relevant subject may also be required in some areas of the Faculty. For entry requirements for all other research degrees we offer, please contact us.

<h2 class="heading heading--sm">English language requirements</h2>

Applicants whose first language is not English must provide evidence that their English language is sufficient to meet the specific demands of their study. The Faculty of Medicine and Health minimum requirements in IELTS and TOEFL tests for PhD, MSc, MPhil, MD are: &acirc;&euro;&cent; British Council IELTS - score of 6.5 overall, with no element less than 6.0 &acirc;&euro;&cent; TOEFL iBT - overall score of 92 with the listening and reading element no less than 21, writing element no less than 22 and the speaking element no less than 23.

<h2 class="heading">Contact details</h2>

<p>For further information please contact the Graduate School Office<br /> e: <a href=""></a> t: +44 (0)113 343 8221.</p>