Do Invasive Dental Procedures Cause Prosthetic Joint Infections? – The PJI Study

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Study aims
Possible outcomes
Potential participants
What does the study involve?
Potential risks and benefits of being a participant
Protection of participants (including Research Ethics Approval)
What can I do if I don't want my data used in this study?
Further information
Contact information


Prosthetic (artificial) replacement of poorly functioning, painful and diseased joints is now a common procedure. However, late prosthetic joint infections (LPJI), caused by blood-borne bacteria (bacteremia), are a common complication with high morbidity, and potential mortality, as well as high treatment, patient and societal costs. In an attempt to reduce the risk of LPJI, dentists in some parts of the world (particularly the USA) are recommended to give prosthetic joint patients antibiotics before invasive dental procedures (IDP). This is called antibiotic prophylaxis (AP). The purpose of this is to reduce the risk of a bacteremia occurring following an IDP that might result in infection of the prosthetic joint. However, there is little evidence to for any association between IDP and LPJI and there are no clinical trial data demonstrating if AP is effective or not. Currently AP is not recommended in the UK for individuals with prosthetic joints but is in the US. Data proving or disproving any association between IDP and LPJI is urgently needed.

Study aims

The aim of the study is to identify if there is any association between the occurrence of invasive dental procedures and development of LPJI.


The PJI-Study will link national data on courses of dental treatment and hospital admissions for LPJI to investigate if there is a link between invasive dental procedures and the development of LPJI. We will address the following questions:

• Is the frequency of invasive dental procedures higher in the 3 months immediately before someone develops a LPJI than in other 3-month periods?

• Is the incidence of LPJI higher in the 3 months immediately following an invasive dental procedure than in the 3 months following dental treatments that do NOT involve an invasive dental procedure?

What are the possible outcomes of this study?

If an association exists, then the widespread adoption of AP in the UK and elsewhere could help reduce the number of LPJI cases each year and the high associated treatment costs. In the US alone, there are ~20,000 LPJI cases each year with a ~$566 million annual treatment cost.
Alternatively, if no association exists, then AP is unnecessary and a clear recommendation against its use could be made. As AP is not currently recommended in the UK this would not have a significant impact other than reassuring clinicians and patients about the safety of this approach. In the US, and other countries where AP is the standard of care, however, stopping AP would save ~$60 million annually, avoid the risk of adverse reactions in those who currently receive AP and reduce the risk posed to society that the use of antibiotics for AP might unnecessarily promote the development of antibiotic resistant bacteria.

Who are potential participants in the study?

All individuals admitted to hospital for late prosthetic joint infections (LPJI) in England.

What does the study involve?

This study uses national hospital admissions data to identify all those individuals in England who developed a LPJI in the period between 1st April 2010 and the 31st March 2017. Data on LPJI hospital admissions will then be linked to national data on NHS dental treatment to see if those who developed LPJI were more likely, or not, to have had an invasive dental procedure in the 3 months immediately preceding the LPJI than in any other 3-month period.

What are the possible risks and benefits of being a participant? 

If this study demonstrates a link between invasive dental procedures and LPJI, this will provide support for the use of antibiotic prophylaxis (AP) before invasive dental procedures in patients with prosthetic joints. If no such link is identified, it will provide reassurance to those with prosthetic joints, their dentists and physicians, carers and those charged with providing guidance on such issues, that current UK guidance not to provide AP for those with prosthetic joints is correct.
In countries such as the US, where AP is recommended for those with prosthetic joints undergoing invasive dental procedures, the demonstration of a link between invasive dental procedures and LPJI would lend support for this guidance. On the other hand, if no link was demonstrated, it would provide support for the concept that AP might not be necessary.
While this research will not directly benefit individuals in the data set, it will help to improve evidence based dental care for all those with prosthetic joints. As it is an observational study, there is no direct risk for participants.

Who is funding this study?

This study is being funded by the National Institutes for Health in the USA.

Protection of Participants (including Research Ethics Approval)

As part of the funding process, this study was subject to rigorous independent scientific review. It was then submitted to the UK’s National Research Ethics Service for ethical evaluation and received full ethical approval on the 5th December 2018 (REC reference: 18/SC/0387 and IRAS project ID: 246818). In addition, because the study involves the use of national patient data records held by NHS Digital (hospital admission data) and the NHS Business Services Authority (dental treatment data), without seeking individual patient consent, the study was submitted to the Confidentiality Advisory Group (CAG). This is an independent body which provides expert advice on the use of confidential patient information – including providing advice to the Health Research Authority (HRA). The CAG approved this project (subject to this information being made publicly available on the University of Sheffield web site) on the 4th December 2018 (CAG reference: 18/SC/0387) effectively giving permission for the study to start. The Sponsor and data Controller for this study is the University of Sheffield.

What can I do if I don’t want my data used in this study?

Anyone who does not want confidential patient information held about them by NHS Digital (or the NHS Business Services Authority) to be used in this, or any other research, can use the National data opt-out programme to have it excluded. Patients can find out more and set their opt-out choice at:

Further information

This study is registered as a clinical trial with the international clinical trial registry ISRCTN at: This web site provides further details relating to this study. In addition, the Funder (NIH) also has a web site that provides more detail about the study and its funding at:

The study Principal Investigator is:

Professor Martin Thornhill
University of Sheffield School of Clinical Dentistry
Claremont Crescent
S10 2TA