Tuesday, 14 September 2010

PICO questions

Since I referenced PICOs in my last blog I thought I'd mention them here as they offer a great structure to help us find evidence for intervention studies. It's all about asking a clear and concise question so that you can - hopefully - find a clear answer.

The P bit stands for the patient or problem you are concerned about.

Let's imagine a 50 year old lady who had a load of amalgams placed mainly when she was young. She's read that dentists crown patients' teeth when they've got big fillings in because it stops them from breaking and losing their teeth.

What's the P here? The P is a problem in a patient - in this case a patient with heavily restored teeth.

The I bit relates to the intervention. In this case the I is a crown (or an onlay). You want to know, as this lady's dentist, whether or not you should crown some of her teeth and - if you're going to - which ones. So you want to compare placing a crown against not placing a crown to know if the crown is better.

So C is your comparison or control. In this case that is a filling - either amalgam or composite. If all we looked at was the survival time of a crown, without comparing it to the filling, we wouldn't know whether the filling might last just as long - or even longer.

Finally O is the outcome or outcomes you're interested in. What matters to the patient in this case? She is probably worried about losing her teeth. So the bottom line will be - does placing a crown mean that she'll keep that tooth longer than if she had just left it with a filling?

Another outcome might also be which restoration has to be replaced most frequently, or what the long term cost is of each treatment. And an outcome that is often forgotten is whether there are any adverse effects: does the tooth die, does it fracture catastrophically so it has to be extracted, does one cause mouth cancer?

We usually decide on one main outcome that really interests us. In this case I'd go for whether or not the tooth was retained longer as without this information it's very difficult to decide whether one is more cost-effective, for example.

So the PICO question here would be:

For an adult patient with an MOD or larger restoration in a molar tooth (P) does a crown or onlay (I) rather than a composite or amalgam (C) result in the tooth being retained longer (O)?

So why do this? Well, if you're going to search for evidence one way or the other - even if it means asking an expert (even though they lie way down the bottom on the hierarchies of evidence) - it is important to have a clear question. From this you can create a search strategy to use with Medline or the Cochrane Library and in a short time you can identify any good papers that might help you answer your question.

For more on this have a look at the Centre for Evidence Based Dentistry website

Monday, 13 September 2010

Managing avulsed teeth...

A few students and I were discussing management of avulsed teeth today. Wanting to find the best evidence of what to do when an adult walks in with their tooth in their hand we searched TRIP Database using the term avulsed tooth, which led us to a couple of systematic reviews looking at management of avulsed teeth and how long to splint them. Try it yourself if you're interested and see what you learn.

Later on I wanted to find some evidence based guidelines on trauma generally so popped 'Dental Trauma' into TRIP instead. This resulted in the following paper: Clinical guideline on management of acute dental trauma at the National Guideline Clearinghouse.

This guideline from 2007 has a succinct summary of what to do for the different types of trauma. It's not perfect in its methodology but appears to be pretty thorough.

The National Guideline Clearinghouse can be a useful site to visit if you're trying to find evidence about interventions. It's one of many online aids now available to help us make more informed decisions about healthcare.

One other paper I came across was a structured search to answer the PICO: How long should we wait for a pulp extirpation after a replantation of an avulsed permanent tooth? (If you're unsure what a PICO is let me know and I'll blog on it...and if you're not in the library you will need to log into Athens to read the paper). The basic take home messages were:
  1. for replanted teeth with closed apices (i.e. very low chance of the pulp being revascularised) elective extirpation of the pulps should be performed within 14 days. 
  2. for teeth with open apices, pulps should be extirpated when there is evidence of pulpal necrosis. 
  3. pulpal extirpation is beneficial in the control of inflammatory resorption but has no proven benefit in control of replacement resorption or other aspects of healing.