Theodore Eliades (ed.)Research Methods in Orthodontics2013A Guide to Understanding Orthodontic Research10.1007/978-3-642-31377-6_5© Springer-Verlag Berlin Heidelberg 2013
5. Clinical Orthodontic Research
School of Dentistry, The University of Manchester, Higher Cambridge Street, Manchester, M15 6FH, UK
One of the great buzz phrases over the last few years is evidenced-based care. However, while this is easy to promote as a concept, we have to carry out the research that is going to provide us with the evidence that will either reinforce or make us change the care that we provide. At this point it is relevant for us to consider the type of investigation or research that is going to give the highest level of evidence, and this is always the randomized controlled trial or systematic review. All other types of study, such as case report, retrospective study, or comparison of case series, do not give us adequate information. As a result, I will confine this chapter to a description of how to carry out a randomized controlled trial.
One of the great buzz phrases over the last few years is evidenced-based care. However, while this is easy to promote as a concept, we have to carry out the research that is going to provide us with the evidence that will either reinforce or make us change the care that we provide. At this point it is relevant for us to consider the type of investigation or research that is going to give the highest level of evidence, and this is always the randomized controlled trial or systematic review. All other types of study, such as case report, retrospective study, or comparison of case series, may not give us adequate information. As a result, I will confine this chapter to a description of how to carry out a randomized controlled trial.
If you are considering carrying out a trial, it is very important to be systematic in your planning, and the first stage of this is to prepare a protocol, and I will outline the steps that are necessary in preparing this important document. It is not my intention to be prescriptive in the outline; I am simply providing guidelines for the potential researcher who hopes to carry out a research project. None of these ideas are my own; they are a condensation of those derived from several readily available sources. Throughout this chapter I will provide examples from a hypothetical project that aims to investigate the influence of functional appliances upon facial growth.
5.2 The Research Protocol and Its Sections
A protocol is a document that explicitly states the reasoning behind and structure of a research project. The preparation of a protocol is the most important stage in the research process and is carried out for the following reasons:
It encourages you to plan the project in detail, before you start.
It allows you to see the total process of your project.
It acts as a guide for all personnel involved in the project
It acts as a “reminder” to you and your supervisor (or coworkers) of the initial structure and aims of the project.
It enables you to monitor the progress of the project.
It is necessary if you need to apply for funding or ethical approval.
All protocols are divided into two main sections: (1) the problem to be investigated and (2) the method of investigation. These sections may be further subdivided as follows:
5.2.1 The Problem to Be Investigated
The research problem
Background (including the literature review)
5.2.2 Method of Investigation
Plan of the investigation (including sample size calculation and statistical methods)
Dissemination of the results
5.2.3 The Problem to Be Investigated
The Project Title
The project title is one of the most important features of the protocol because it attracts the attention of the potential reader. It is, therefore, necessary to make it as short and to the point as possible. Let us consider two possible examples:
An investigation to evaluate the effectiveness of functional appliances for the treatment of Class II skeletal growth anomalies.
This title is overlong and states the obvious in a rather “wordy” way. It goes without saying that because it is the title of a research protocol, it is an investigation that will evaluate something. A preferable approach may be:
Do functional appliances modify facial growth?
The second title comes straight to the point without stating the obvious. It not only attracts the attention of a reader but it immediately tunes them into the subject matter.
The Research Problem
Before you start to develop a research project of your own, you must first identify a research problem. This is a difficult step particularly if you are an inexperienced researcher. Research problems are explanatory devices; they are carefully designed sentences about what you intend to find out.
It is difficult to design a problem statement and you should give it a great deal of careful thought. When you write the problem statement, your words must show an understanding of the research phenomena and should explicitly reveal your purpose.
You should go directly to the problem in the first sentence of page 1. Resist the temptation to give background or set the stage for the problem. When the protocol is ready, the readers will want to know the purpose of the study immediately. They will not want to search through several pages of text to discover what the protocol is about. To be effective your opening words should be clear and demand attention, for example:
In this study I intend to find evidence that facial growth can be modified by functional appliances. If I can show that this occurs, this will be an important finding for orthodontic care.
This will be an investigation to evaluate the effect of functional appliances upon facial growth.
If we examine the two statements above, statement (a) is easier to read because it is in the first person. This should be your preferred writing style as opposed to the use of passive voice (example b). You should, however, be careful that the first person is not overused and that your protocol does not read like a “letter to mum.”
Avoid the look–around approach to a research problem. It is very important to avoid the “let’s start a project and see what happens” approach. This will inevitably lead to a poorly coordinated and cumbersome project that drifts and may not have a well-defined ending. As a result, the statement of the problem should be explicit.
Background (Including the Literature Review)
The most important feature of the background to the project is that it should be brief and direct to the point. For a research protocol the background should be no longer than two single-spaced pages of A4 paper. In this section you should concisely review the literature that is relevant to the problem that you are trying to solve and is current. While it may be tempting to include all the literature, particularly classic papers, you should carefully consider whether to include research that is published more than 5 years before your project. In this respect it is probably good practice to limit the number of papers quoted to less than 20.
When you write the review, you should draw attention to the good points and the deficiencies of the studies quoted. You should also remember that it does not always mean that if a study has been published in a journal, it is flawless in its methodology and conclusion. Nevertheless, you should not be too critical of previous investigators because research technology and understanding of data analysis is a fast-moving field. Remember, if your study is published and it is considered state of the art today, it could be torn to shreds by neophyte researchers in 10 years’ time!
In terms of writing style it is good practice to make your writing flow. There is a tendency to introduce concepts and previous studies by simply going through a shopping list of papers; for example,
McNamara has shown that the Frankel appliance produces an increase in mandibular length of 3 mm. Pancherz (1979) used Herbst appliances and showed an effect of 3 mm increase in mandibular length; this is in agreement with a study by Hansen (1984). However, Tulloch et al. (1990) have suggested that it is not possible to come to any conclusions concerning the effect of functional appliances.
It is better to take the following approach:
There have been many retrospective investigations that have concluded that either fixed or removable functional appliance have a growth-modifying influence on the mandible (McNamara 1984; Pancherz 1986; Hansen 1991). However, Tulloch et al. (1990) in a review of this literature have been critical of past research, and concluded that most studies are characterized by weak designs. As a result, it is not possible to come to any conclusions concerning the effect of functional appliances.
The literature review should logically lead to the statement of the aims of the proposed project.
The aims of the project should be explicitly stated. These should be confined to the intention of the project, and they should arise from the literature review which is likely to show where more research is needed.