Questions, questions and, please, more questions

I had a discussion with a student this afternoon about a finals case. I wondered how or if he was using those EBD skills taught back in the 2nd year. There was much to discuss.

The case is a person with periodontal disease (with 30-50% bone loss) who requires composite build-ups, a couple of crowns and a partial denture. I asked the following questions, amongst others:

1. Can you give the patient an idea of how long he can expect to retain the worst-affected teeth?

2. What is the evidence that crowns are any more successful than large fillings?

3. If the composite build-ups are for posterior teeth, what are the alternatives and how do they compare?

4. Which lasts longer in posterior teeth - composite or amalgam?

Now this wasn't me trying to catch the student out - there weren't many confident answers coming back at me. What I wanted to encourage was the following:
1. to ask these questions yourselves when you are managing patients
2. to think about how you will answer it by searching for evidence. Is there a systematic review to help? If not, what trial design is the best one to answer your question?

For the prognosis question we'd want a study that followed a bunch of patients with severe periodontitis and see if / when they lost their teeth. That's a cohort study.

For all the others we want a study that compares two or more interventions, ideally in a random way. That would be a randomised controlled trial.

Please do ask these questions and let me know how you get on.