Trends in Orthodontic Research Over the Last Fifty Years

Objectives: To identify trends in orthodontic research as reflected by publications indexed on Medline over the last fifty years.  The variables to be examined in this study include age of study participants, animal vs human subjects, and funding source.

Methods: MeSH term searches were performed for the term Orthodontics on Medline using the PubMed search engine.  Articles were searched by decade from 1960 to 2010.  To study age, the all child (0-18 years) limit was selected.  Orthodontics was then searched and the number of search results was collected for each of the five decades.  The limit was then changed to all adult (19 + years) and the same search strategies were employed.  Lastly, the total number of child and/or adult related publications per decade was obtained.  The same search strategies were employed to study the humans/ animals limits and the research support U. S. government/ non U. S. government limits. .  The funding support limit only pertains to articles processed after 1975, so this particular limit was only searched from 1980 to 2010.

Results: Over the last fifty years, publications involving only adult subjects increased from 9% to 29% while those involving only children decreased from 78% to 47%.  Publications using only animals increased from 2% to 9% while those involving only humans have decreased from 97% to 90%.  The proportion of publications supported by funding only from the U.S. government decreased from 32% to 8% over the last thirty years.

Conclusions: Trends in Orthodontic research include (1) an increase in the proportion of adults to children participants, (2) an increase in the proportion of studies using animals as opposed to humans, and (3) a reduction in the percent of research funded by the U.S. government. These trends are consistent with trends in practice reported by Melsen (2011).