Study design
The study was carried out between Jan 2010 and June 2011. The study was population based and using a rapid assessment survey method. This approach was adopted because there was limited time and resources for collecting the data before the introduction of the national oral health policy. The survey tool was a questionnaire to assess the oral health service utilization and pattern of oral hygiene practices of participants. The survey tool was administered in person and had a target length of fifteen minutes. It was developed and refined by the authors with input from Dentists in other parts of the country. It was designed for ease of use with minimal interviewer training.
Study population
The estimated total population of Nigeria at the time of conducting this study was 159 million, out of which 54.94% are aged 18 to 64 years while 3% are aged 65 years and older [17]. The target population for this survey was approximately 92 million persons aged 18 years and older.
Study location
The study was conducted in Nigeria, which comprises 36 states and the federal capital territory. The states have been categorised into six geo-political zones or regions for ease of administration namely North-Central, North-East, North-West, South-East, South-South and South-West. Each state is further divided into three senatorial districts and each senatorial district divided into local Government areas (LGA). There are 774 LGA’s in Nigeria altogether. The LGA is the smallest unit of administration in the country.
Sampling method
We used a multi-stage cluster sampling method to conduct this survey. Five states in the north-eastern geo-political zone that were experiencing socio-political problems (namely Adamawa, Zamfara, Plateau, Borno, and Yobe) during the data collection period were excluded from the sampling frame. Eighteen out of the remaining 31 States were randomly selected for the study. The selected states included Abia, Anambra, Bayelsa, Benue, Ekiti, Enugu, Imo, Kaduna, Kano, Kogi, Kwara, Lagos, Nasarawa, Niger, Ogun, Ondo, Osun and Oyo. One LGA per three senatorial districts in each of the 18 states was randomly selected using the list of LGA’s in the state as the sampling frame. In total, 54 LGA’s were visited during data collection.
Sample selection
The research assistants were dentists resident in each of the selected states. They regularly met with the health care team in the selected LGA to obtain permission to conduct the study. Before the visit, community leaders were informed of the proposed study, their consent sought and they were encouraged to mobilise participants from their locality for the study. Participants were sequentially recruited based on the following criteria: must be an 18 years or older, should reside in the LGA and be willing to participate in the research. Subjects 18 years and below or who were unwilling to participate were excluded from the study.
Data collection
Data collection was done in a central location in the community (local government headquarters or town hall). Data on demographic characteristics, oral health service utilisation, patterns of oral hygiene practices, and self-reported oral health status were collected using a structured questionnaire. The occupation was recoded for data entry using the UK registrar’s occupation classification [18] while age was recoded using the decades of life. The second section asked questions on oral hygiene practices and oral health services utilization patterns. Under oral hygiene practices, we specifically enquired about the tools used for cleaning the mouth, frequency of daily mouth cleaning, use of adjunct tools such as dental floss and mouthwash and the estimated duration of mouth cleaning. Under oral health service utilization, we enquired about history of previous visits to oral health care units and reasons for those visits.
Literate participants completed the questionnaire personally while trained interviewers assisted illiterate subjects using pidgin English (a local form of English in the country) or one of the three main languages in the country. The survey instrument was translated and back translated to pidgin and three other major languages including Yoruba, Ibo and Hausa. The translated versions were used during the training and standardization of the interviewers. Interviewers used the translated versions strictly for illiterate persons. The questionnaire was pretested to ensure simplicity and ease of understanding by the participants. Changes were made to the questionnaire before data collection.
Ethical considerations
Ethical clearance for the study was obtained from the Ethical Review Committee of the College of Health Sciences Obafemi Awolowo University Ile-Ife Nigeria. In addition, permissions to conduct the study were also obtained from the chairpersons of all the selected LGAs, through the directors of primary health care. The researchers explained to all study participants the scope, aims and objectives of the study as well as their rights to participate or withdraw from the study with no penalty. All study participants gave verbal consent and were assured that their confidentiality would be maintained.
Data analysis
Data entry and analysis was done using SPSS statistical software version 16.0. Univariate analysis was carried out; means, standard deviation were computed for quantitative variables and frequency distributions generated for qualitative variables. Bivariate analysis to identify associations between oral hygiene habits (i.e. the dependent variables namely frequency of tooth brushing, tool used and duration of toothbrushing) and sex, age, geo-political zone, and educational status (the independent variables) of the study participants was also carried out. The chi-squared test was used as test of significance for comparing proportions for more than 2 groups while the fishers exact was used for comparing differences in proportion between two groups. The student t-test was used to compare differences in age. Logistic regression analysis was conducted to identify factors independently associated with adequate tooth brushing frequency in the population (defined as brushing two or more times daily). Associations were considered significant when the p-values were equal or less than 0.05.