This is a cross-sectional study. Data on DDA were collected as part of a household survey to determine the prevalence of early childhood caries (ECC) and associated maternal psychosocial risk factors. The study participants were 1539 children aged 6 to 71 months resident in Ife Central Local Government Area of Osun, State, Ile-Ife, a semi-urban community. The survey was conducted between December 2018 and January 2019.
Sample size: The minimum sample size for the study was calculated using the formula for cross-sectional studies in populations greater than 10,000 . The variables for determining the sample size included the prevalence of ECC prevalence which was 6.6 % , the margin of error was 5%, and the confidence level was 95%. The minimum sample size required for the study was 1,439 mother-child dyads. This was rounded up to 1440.
Sampling and recruitment procedure. A multi-stage sampling technique was used for the study. The first stage consisted of selecting 70 of the 700 enumeration areas in the local government by a simple random, balloting method. This percentage of the population is considered representative for a household survey . The second stage consisted of selecting eligible households within the enumeration sites of the survey. At each of the enumeration sites, every other household on each street was eligible for recruitment of a mother-child dyad. The third stage consisted of selecting respondents for an interview and clinical examination.
Only one child and mother dyad in each household was eligible for participation in the study. Only children who were below the age of 6 years, who were living with a caregiver, who were present at the time of the survey and for whom parental consent for study participation was obtained, were recruited for the study. Children who had chronic medical conditions that required prolonged use of sweetened medications and those with medical conditions that increased their risk for caries were excluded from the study. Where there was more than one child eligible for study participation, the study participants was identified by balloting. The other child(ren) was/were offered the opportunity to have a clinical examination. All participants were informed about the screening outcome and referred for treatment when oral diseases were identified. Treatment for ECC was offered free to study participants.
Recruitment of study participants continued until the required minimum sample size of 1440 was reached. Whenever a household declined (19 households declined) to participate, the next eligible household was substituted. The number of participants to be recruited from each enumeration site was determined by proportioning the study’s sample size per the population of the enumeration site. Ethical approval for the study was obtained from the Obafemi Awolowo University Teaching Hospitals Complex Health Research Ethics Committee (NHREC/27/01/2009a & IRB/EC/0004553).
Data collection. Data obtained included the children’s socio-demographic characteristics (age, sex, and socioeconomic status). The definition of socioeconomic status was based on a multiple-item index  that had been used in prior studies in Nigeria [10, 11]. The composite score was based on maternal occupation and paternal education. Enrolled children were classified according to one of five socio-economic classes: class I, upper class; class II, upper-middle class; class III, middle class; class IV, lower middle class; and class V, lower class. The classes were then categorized as high (Classes I and II), middle (Class III), and low (Classes IV and V).
The oral examinations were conducted by five calibrated dentists. Intra-examiner agreement for each of the dentists was calculated by use of the paired sample correlation, whereas the inter-examiner agreement (between the dentists and the trainer) was calculated by use of Cohen’s kappa coefficient. The intra- and inter-examiner reliability tests were all greater than 0.80, which is considered an acceptable level of agreement. Children were examined under natural light, either sitting on a chair or on their mother’s lap.
The teeth were examined wet for the oral hygiene status assessment; thereafter, debris was removed with gauze before examination for the presence of ECC and DDA. Oral hygiene was assessed by use of the index of Greene and Vermillion . The index teeth and surfaces examined were the facial and lingual surfaces of teeth number 51, 55, 65, 71, 75, and 85. The debris and calculus scores were recorded, added, and divided by the number of surfaces examined to get the OHI-S score. Oral hygiene was scored good when the scores ranged from 0.0 to 1.2; fair when the scores ranged from 1.3 to 3.0; or poor when the scores was 3.1 and above. For children who did not have the index teeth, all the teeth present were scored, and their average determined before being classified.
ECC was determined using the decayed-missing-filled teeth (dmft) index as recommended by the World Health Organization . The dmft score was obtained by adding the d, m and f scores for each child. ECC was considered present when the dmft score was >0 and absent when the dmft was 0.
The presence or absence of any DDA listed in Table 1 was determined according to the criteria of Temilola et al  and Folayan et al . Also, hypomineralized primary second molar was defined as demarcated white, yellow or brown opacities that were greater than or equal to 2 mm in diameter, present on any of the surfaces of the primary second molar [15, 16]. Fluorosis assessed as presence or absence of tooth mottling . A diagnosis of amelogenesis imperfecta was made when there was enamel hypoplasia and/or hypomaturation or hypocalcification randomly affecting multiple teeth in no depictable chronological order .
Data analysis: Data for this study were derived from the 918 young children aged 3-5 years old who had all their primary teeth erupted. Descriptive analysis was conducted to determine the prevalence of each lesion. Multivariable logistic regression was conducted by use of the Poisson regression analysis to determine if the presence of a DDA, ECC and oral hygiene was associated. The estimated coefficients, expressed as prevalence ratios (PRs) and their 95% confidence intervals, were calculated. We chose to use the Poisson regression analysis because it reduces the risk for overestimation of the prevalence ratio especially when an adjusted estimate needs to be made. The analysis also used a robust variance estimator to allow for direct estimation of the PRs. Statistical analyses were conducted with Intercooled STATA (release 15) for windows. Statistical significance was inferred at p <0.05.