Study population and sampling
The present interventional study was conducted in primary school teachers. By census, all primary school teachers in Arak, Markazi Province, Iran (n = 664) were asked to participate in the study. Those who accepted to participate were assigned to two intervention groups of educational leaflet and oral presentation according to two geographic regions of the city.
Baseline data collection
All primary teachers in both groups attended regular sessions according to their professional development program mandated by Department of Continuing Education, Ministry of Education. In the first stage, in coordination with the authorities of the Education Department of Markazi Province, teachers in both groups were asked to complete an anonymous self-administrated questionnaire in two different sessions.
Interventions
In the second stage, interventions, including an oral presentation and an educational leaflet whose contents were prepared based on the “Save Your Tooth” poster (IADT 2011) and the most recent scientific evidence, were applied [28, 29]. Both the oral presentation and the educational leaflet contained information about tooth fracture, luxation, and avulsion, and explanation about appropriate steps in the management of traumatized teeth. These materials were prepared in the native language (Farsi) and included colorful pictures (Fig. 1). In the oral presentation group (n = 341), a meeting was held and a brief explanation was provided about the purposes of the study; then, a 45-min oral presentation was delivered by one of the researchers. In the educational leaflet group (n = 323), a letter explaining the study was attached to the educational leaflet.
The teachers working in the city were categorized to the two groups by the Ministry of Education based on geographical location of the schools. We randomly assigned the interventions (oral presentation and educational leaflet) to these groups.
Follow up data collection
In the third and fourth stages of the study, one and six months after the intervention, the same questionnaire was completed by the teachers. The answers were then scored and the data were statistically analyzed to compare the pre- and post-test results.
Questionnaire
In addition to demographic data (age, employment status, education level, and work experience) and history of exposure to TDIs, the questionnaire (Additional file 1: Appendix 1) included the following items:
Knowledge
The teachers were asked to answer eight questions on the emergency management of TDIs using multiple-choice, “yes-no”, and “I do not know” answers. Two questions had two correct answers. Incorrect and “I do not know” answers scored = 0 and correct answers received a score of 1. By summing up the scores of eight questions, the knowledge score of each teacher was calculated (range: 0 to 10).
Self-reported practice
In this part, four paper cases (five questions) of TDIs were presented, each representing a case with a certain TDI. The cases were almost similar to the content of the oral presentation and the educational leaflet. Two questions had more than one correct answer: one question had three correct answers, and another one had two correct answers. Based on the teachers’ answers, the self-reported practice score (range: 0–8) was calculated as described for the knowledge score.
Teachers were requested to write a unique code on the top of their three questionnaires. This code was used to assess individual changes before and after the intervention.
In terms of face and content validity, a valid reference book [30], latest guidelines for the management of TDIs [28, 29], and similar previous studies [10, 17, 25,26,27] were used to collect the questions. Then, the questionnaire was piloted to assess its validity and reliability. Two experts in community oral health, one expert in pediatric dentistry, and one epidemiologist assessed the content validity of the questionnaire. The reliability of the questionnaire was evaluated and approved through test-retest on 15 primary school teachers from three schools of the city at an interval of 10 days. These teachers were excluded from the main study. The Kappa coefficient was above 70% for different questions.
Ethics approval
Ethics approval was obtained from the Research Ethics Committee of Tehran University of Medical Sciences (code IR.TUMS.REC.1394.1383). This longitudinal and interventional study was completely voluntary and the responses were anonymous. Moreover, all respondents were free to leave the study in each phase. Informed consent was obtained from all participants in the beginning of the study. In the start page of the questionnaire, the participants were informed about the objectives and protocol of the study. Moreover, they were asked to present their informed consent by signing the bottom of this page.
Statistical analysis
SPSS version 22 for Windows (SPSS Inc., Chicago, IL, USA) was used for statistical analysis. Repeated measures ANOVA was applied to analyze the data. In this test, knowledge and self-reported practice before and after the intervention were considered as repeated factors and demographic variables (age, employment status, education level, and work experience) and type of intervention were considered as between-subject factors. A linear regression model was used to analyze the relationship between independent variables and knowledge and self-reported practice scores. The association between knowledge and self-reported practice was explored using Pearson correlation coefficients. The level of significance was set at p < 0.05.