Do dental research journals publish only positive results? A retrospective assessment of publication bias

BACKGROUND: The study aimed to determine the presence of publication bias in the top five dental journals with high impact factor published during 2007–2016. MATERIALS AND METHODS: The journals included are Journal of Clinical Periodontology, Dental Materials, Clinical Oral Implant Research (COIR), Journal of Endodontics, and Journal of Dental Research (JDR). The content of these journals was hand searched by two authors for scouring the proportion of positive or negative results. Articles showing two outcomes (primary and secondary) were registered depending on the primary result. RESULTS: The present study revealed higher percentage of statistically significant results in the published dental literature. Of five journals, JDR has shown fewer tendencies toward publication of nonsignificant results, whereas COIR has evidenced the highest publication of nonsignificant results. The journals with higher impact factor showed significantly different acceptance rate for research with positive results. However, year-wise publication (2007–2016) did not depict any significant difference. CONCLUSION: In dental research journals, articles with positive results are finding a better way in getting published compared to articles with negative results.