Evidence-based dental practice: searching the literature and writing a report

Final Step: Writing the Abstract:
The abstract is the first thing your readers will look at, but it is the last thing you will write. This is because the abstract is a summary of your paper and uses language taken directly from it.

An abstract is a brief summary which condenses in itself the argument and all the essential information of a paper.  An abstract allows the reader to survey the contents of a paper quickly and decide whether to read the full text. It needs to be dense with information but also readable, well-organized, brief, and self-contained.  Abstracts are generally 100-250 words long.

An Abstract Must Accurately Reflect the Paper It Summarizes:

• it uses the same language as the paper, especially key words and concepts
• it includes only information that actually appears in the paper
• it correctly reflects the purpose and content of your paper
• the sections of the abstract should be roughly the same length proportionally as the sections of the paper

An Abstract Must Be Self-contained
An abstract is a stand-alone document. You can not ask  your reader to go to the paper itself for an understanding of what you say in your abstract.

• define all acronyms and abbreviations (except standard units of measurement)
• spell out names of tests and drugs (use generic names for drugs)
• define unique terms
• do not include references. An exception is made for sources whose theory, method or measure is being used. For example,

Using Hall’s (2002) method of radiographic analysis, we sought to design a system for interpreting panoramic x-rays.

An Abstract Must Be Clear and Concise:

• make each sentence as informative as possible, especially the lead sentence
• include in the abstract only the most important concepts, findings, or conclusions
• avoid sentences that contain no real information (Implications for practice are discussed).
• the question and what was done can often be written in one sentence, for example:

To investigate the relationship between pacifier use and early childhood caries, we conducted a search of four electronic bibliographic databases.

Analysis of a Sample Abstract (Peressini, 2003):
[1] This evidence-based study of the literature investigated the relationship between pacifier use (with and without sweetening and prolonged or short-term) and early childhood caries (ECC). [2] The review was based on evidence from 3 main sources: a search of several electronic bibliographic databases, a review of the references from relevant studies for additional potentially relevant articles, and a review of several dental textbooks. [3] A total of 74 articles were reviewed. [4] Of these, 8 were deemed relevant and were critically appraised according to a “causation checklist| of 13 items. [5] The 8 studies assessed were methodologically inconsistent in terms of definitions of ECC, diagnostic criteria for identifying carous lesions, dental examination procedures, interviewing methods, and description of pacifier use. [6] None of the studies achieved a score greater than 6 and hence none was considered to present strong evidence. [7] Six studies did not control for confounding variables, and the conclusions they generated were inconsistent. [8] The evidence from the other 2 studies, which did control for confounding variables, presented slightly stronger evidence, but they indicated no statistical difference in pacifier use between children with and those without ECC; furthermore, the reported odds ratios suggested that pacifier use might have had a mildly protective effect. [9] Overall, the evidence does not suggest a strong or consistent association between pacifier use and ECC.

Notes:
[1]  Identifies the nature of the article (evidence-based review of the literature) and the question investigated. Note how concisely Peressini describes the variables for pacifier use.
[2] Summary of the 3 types of sources used, introduced with a colon and separated with commas. Answers the question: “How did you do your search?”
[3] Gives the total result of the search.
[4] Narrows down to the final result of the search and states how the studies were evaluated.
[5] Overall summary of the assessment of the studies, identifying 5 methodological issues.
[6] Identifies the overall strength of the studies. Repeating the word ‘none’ reinforces that the overall strength was low.
[7] Summarizes the main weaknesses of most of the studies.
[8] This sentence discusses the two best studies and has two parts: the first summarizes their common strengths and the second (beginning with “but”) summarizes their weaknesses, which outnumber the strengths.
[9] The concluding sentence summarizes the paper’s conclusion. Note the structure: it begins with a summarizing word (“Overall”); reminds the reader that this is an evidence-based review (“the evidence”); uses a verb that offers a judgment (“does not suggest”) and finishes by reminding the reader of the problem being studied (“pacifier use and ECC”).