Individual Studies

Chapter 7

Individual Studies


The aim of this chapter is to show which types of study are needed to answer particular questions, outline some hints for searching, and introduce the basic questions to address in critical appraisal.


On completion of this chapter the reader will be able to identify the most appropriate study design to answer questions, and be aware of the three basic questions to address in a critical appraisal.

Using Individual Studies

If there are no evidence-based guidelines, Cochrane reviews or other systematic reviews to address our clinical problems then we must look to individual studies.

What Type of Study?

The type of study that we need to look for depends on the question that we need answered (see Table 7-1).

Table 7-1 What is the most appropriate study design to answer the question?
Clinical problem Most appropriate study design
Treatment/prevention, aetiology RCT
Prognosis Individual inception cohort study with ≥ 80% follow-up
Diagnosis Validating cohort study with good reference standards
Differential diagnosis/symptom prevalence study Prospective cohort study with good follow-up
Economic and decision analyses Analysis based on clinically sensible costs or alternatives; systematic review(s) of the evidence; and including multi-way sensitivity analyses
Acceptability, appropriateness and quality of care, reasons for undergoing treatment Qualitative studies


Let us consider examples of the main question types:

  • What is the best type of restoration for carious primary molar teeth?

  • What is the best method of preventing root caries in adult patients?

  • What are the side-effects of using chlorhexidine mouthwash for the treatment of periodontal disease?

  • Are digital x-ray systems better at diagnosing caries than film-based systems?

  • Are school-based toothbrushing programmes cost-effective?

  • What are teenagers’ reasons for undergoing orthodontic treatment?


As before, you need to develop a PICO question for each of these questions (Table 7-2).

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Table 7-2 PICO questions
Question Patient Intervention
Jul 23, 2015 | Posted by in General Dentistry | Comments Off on Individual Studies
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