Abstract Objective:

To evaluate the association of publication bias with obtaining positive or negative results in the Doctoral thesis of Iranian dental schools.

Material and Methods:

In this cross-sectional study firstly we collected all the abstracts of Doctoral and post-doctoral thesis belonging to electronic archives of five Iranian dental schools there after the analytic abstracts were included and in the second phase, we try to search resulting articles with searching in Google Scholar. Data were analyzed using descriptive statistics and a Chi-squared test, Pearson's correlation coefficient, Fisher's exact test, and Logistic Regression Results: Out of 483 reviewed thesis abstracts 269 cases were included (55.7%) 153 of which were accessible as papers (56.9%). In 67.7% of the reviewed thesis, positive results were obtained.

There were significant relationships between publishing and publishing in international journals with two variables:

Study type and field (p<0.05). In vitro studies, clinical trials and studies in the field of oral diseases and periodontics had a higher rate of publication in the form of articles. Retrospective studies and those in the fields of endodontics and oral pathology had a higher rate of publication in journals with international indexes. Using regression logistic model showed that the probability of publishing positive data was greater (18-31%) than negative data. It was shown that the specialty field affected the relationship between the chance of publication of the article and the positive/negative results (p=0.008), increasing the chance of publication to 31% Conclusion: There was publication bias in reviewed dental articles.