Antibiotics in Dentistry Summarised – MUST KNOW!

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If you prefer videos, watch the youtube video where we cover when to refer to A&E, when to prescribe antibiotics and what you should prescribe!

Ok so we’re not gonna go into detail on how antibiotics work and the different types but instead, we’ll cover the basic essentials you need to know. we’ll go through each disease where you might need to prescribe antibiotics and for each one we’ll mention when you should refer them to A&E instead, when you should prescribe antibiotics and what you should prescribe.

Dental Infections

The first one I wanna start with is dental infections or abscesses. It could be an acute apical abscess, chronic apical abscess or a lateral periodontal abscess. These can sometimes present as large swellings and at times the infection or the swelling might be so severe that you might need to send them to A&E.

The times when you should refer to A&E are: number 1, If they have a temperature higher than 39.5 degrees celcius, Number 2, If there are signs of spreading cellulitis, Number 3. VERY severe swelling. Some of the ways to check this are: is the patient struggling to swallow or stick their tongue out, Is the swelling compromising the airway, or is the patient struggling to close their eye. And another way you can check is by trying to palpate the lower border of the mandible. If you can’t palpate it, they need to go A&E.

In all these cases, you should still try to establish drainage but regardless of whether you were successful or not, you need to send them to A&E because they might need IV antibiotics. Now the best way to do this is to call the local hospital switchboard and ask to speak to the max-fax on call. You can then describe situation and suggest IV antibiotics. If they agree you can then send the patient to A&E with a brief letter of the history. This way, once the patient gets to A&E the max-fax on call will already be aware of the situation and they can get bleeped when the patient arrives.

Ok so we got all the severe cases out of the way, if the patient doesn’t need to go A&E when would you prescribe antibiotics for acute or chronic or periodontal abscesses. Most of the time removing the source of infection can be enough but you should prescribe antibiotics as an adjunct treatment when: there is systematic involvement like a high temperature or malaise and when the infection is spreading, for example a large swelling, lymph node involvement or cellulitis. In all of these cases, you should try and establish drainage and also prescribe antibiotics.

The first line antibiotic for acute or chronic or periodontal abscesses is Amoxicillin. You would prescribe 500mg to be taken 3 times a day for 5 days. If the patient has a penicillin allergy, the second line antibiotic is Metronidazole and you would prescribe 400mg three times a day for 5 days. In very rare cases you might get a patient that’s allergic to penicillin AND takes warfarin, which is a contraindication for metronidazole. In that case you should speak to a specialist before prescribing Clindamycin or Clarithromycin because these antibiotics contribute to antimicrobial resistance and could cause bowel infections.

NUG and Pericoronitis

Ok so next on the list is pericoronitis and necrotising ulcerative gingivitis. And I’ve put these two together because the antibiotics you would prescribe are the same. But first, referring to A&E. Pericoronitis is the one that you might need to refer to A&E and the signs for it are exactly the same as we discussed before for abscesses. You just have to keep in mind because pericoronitis is at the back of the lower arch, there’s lot of spaces it can spread to so sometimes you do see some very large swellings, so watch out for all of the signs I mentioned before.

So when would you prescribe antibiotics, well in mild cases of necrotizing ulcerative gingivitis local measures like a scale and oral hygiene instructions might be enough but in severe cases you would always prescribe it as an adjunct treatment. For pericoronitis as well, you should always try to control it with local measures like debridement and irrigation, good oral hygiene and Corsodyl mouthwash, But you should prescribe antibiotics if, there is systemic involvement or a spreading infection as we talked about before.

The first line choice of antibiotic for pericoronitis and necrotizing ulcerative gingivitis is Metronidazole because of the gram negative anaerobic nature of these infections. You would prescribe Metronidazole 400mg to be taken 3 times a day for 3 days. If the patient can’t take metronidazole because they take warfarin or if they’re pregnant or if they have an alcohol dependency, you would prescribe Amoxicillin 500mg to be taken 3 times a day for 3 days.

Prophylaxis for Infective endocarditis

So the ones we’ve covered so far were the most common ones that you’ll be dealing with but there some are still others we needs to go through. Firstly, antibiotic prophylaxis for patients who are at risk of infective endocarditis. It used to be that you would prescribe antibiotics before dental treatment for a wide variety of heart conditions but in 2008 NICE introduced new guidelines which made it so that it is recommended for some specific cases.

And these are patients with a prosthetic valve, patients with a previous episode of infective endocarditis, patients with a congenital heart disease, patients with an acquired valvular heart disease with stenosis or regurgitation and patients with hypertrophic cardiomyopathy. Now you wouldn’t prescribe antibiotics for any dental treatment, only invasive ones.

Invasive treatments for Infective endocarditis – taken from SDCEP Drug Prescribing

So if you’re about to do invasive dental treatment on one of these high risk patients, you should contact their cardiologist to see if they recommend antibiotic prophylaxis. If they do, they’ll most likely want you to prescribe 3g of Amoxicillin to be taken an hour before the treatment. And if the patient is allergic to penicilin 600mg of Clindamycin an hour before.


Another scenario where you should prescribe prophylactic antibiotics is when you reimplant an avulsed permanent tooth. The IADT released a new set of guidelines this year and it recommends Amoxicillin as a first-line antibiotic but oddly doesn’t mention dosages or anything. But the American Academy of Pediatric Dentistry published a paper that mentioned a standard 500mg Amoxicillin course for 7 days. And for children, 50mg per kg per day divided into doses every 8 hours.


And finally, the last one we wanted to talk about is sinusitis. This was another one where antibiotics were more commonly prescribed for but the new guidelines say to only prescribe antibiotics if there is persistent symptoms or purulent discharge lasting at least 7 days or severe symptoms. They advise Amoxicillin 500mg taken three times a day for seven days or Doxycycline 100mg where you take 2 capsules on the first day, followed by one capsule daily for 6 days. For these patients you should also always advise menthol steaming, painkillers and over the counter decongestants.

A flowchart the use of antibiotics – Taken from SDCEP Drug Prescribing

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