Gingival health was quantified using the ORI (Oral Rating Index), an oral classification index, following the criteria proposed by Kawamura. The ORI was based on the examination of four areas: the buccal surfaces of the maxillary anterior teeth, the buccal surfaces of the mandibular anterior teeth, the palatal surfaces of the right maxillary molars, and the lingual surfaces of the right mandibular molars. To determine each individual's ORI level, observable gingival characteristics and the accumulation of calculus and dental plaque were assessed, after which the individual was classified on an ordinal scale. The index was recorded without manual instruments, under natural light, and the decision was made within approximately 10 seconds. In cases of uncertainty, the examiner assigned the lowest score as the representative value for the individual.

Assessed during the intraoral examination.

For the diagnosis of dental caries, the procedures and criteria of ICDAS II were followed. The protocol described by this system recommended tooth brushing and drying prior to caries detection; therefore, the teeth were brushed with a disposable toothbrush and then dried with gauze. The system used two digits to record each tooth or surface: the first digit referred to restorations and sealants, and the second to the dental caries diagnosis. In this study, recording was performed per tooth, corresponding to the worst condition observed among its surfaces.

In the ICDAS II system, codes 1 and 2 record early non-cavitated caries. However, because data collection occurred in kindergarten settings without the possibility of drying teeth with compressed air, code 1 for smooth-surface lesions could not be used. As anticipated in ICDAS II guidelines for epidemiological studies, codes 1 and 2 were therefore combined and recorded as "A" in this study.

Assessed during the intraoral examination.

The criteria for assessing malocclusion followed Bjork, Zhou, and Grippaudo. Malocclusion was classified into three groups: (1) occlusal anomalies (anterior crossbite, edge to edge bite, increased overjet, anterior open bite, deep bite, posterior crossbite, scissor bite); (2) space anomalies (crowding); and (3) dentition anomalies (supernumerary teeth, agenesis, malformations). Anterior crossbite, edge to edge bite, increased overjet, anterior open bite, and deep bite were determined using horizontal and vertical overlap measurements. Horizontal overlap was recorded as the greatest distance between maxillary and mandibular incisors parallel to the occlusal plane; vertical overlap was the greatest distance between their incisal edges.

Assessed during the intraoral examination.

The criteria used to diagnose traumatic dental injuries were based on WHO recommendations. Teeth affected by dental trauma were coded as follows: 0 - No signs of injury; 1 - Treated injury; 2 - Enamel fracture only; 3 - Enamel and dentine fracture; 4 - Pulp involvement; 5 - Tooth loss due to trauma; 6 - Other damage; 9 - Tooth excluded Assessed during the intraoral examination.

The scale is composed of variables that correspond to factors included in the Parents' Beliefs and Attitudes Questionnaire. This scale assesses beliefs and attitudes related to the child's toothbrushing and includes two variables: the importance and intention of brushing the child's teeth, and parents' self-efficacy regarding the child's toothbrushing. All items use the same response format: a 5-point Likert scale ('strongly agree', 'agree', 'neither agree nor disagree', 'disagree', 'strongly disagree'), scored from 1 to 5. Each variable score corresponds to the mean of the items within its respective factor, resulting in values ranging from 1 to 5. Lower scores indicate less positive beliefs and attitudes, whereas higher scores indicate more positive beliefs and attitudes. Assessment is performed at the moment when parents complete the questionnaire.

The scale is composed of variables that correspond to factors included in the Parents' Beliefs and Attitudes Questionnaire. The scale of parents' beliefs and attitudes regarding the control of cariogenic diet includes the following variables: the importance and intention of controlling cariogenic food intake, and parents' self-efficacy related to the control of cariogenic diet. All items use the same response format: a 5-point Likert scale ('strongly agree', 'agree', 'neither agree nor disagree', 'disagree', 'strongly disagree'), scored from 1 to 5. Each variable score corresponds to the mean of the items within its respective factor, resulting in values ranging from 1 to 5. Lower scores indicate less positive beliefs and attitudes, whereas higher scores indicate more positive beliefs and attitudes. Assessment is performed at the moment when parents complete the questionnaire.

This group of variables gathers information on parents' behavior regarding access to oral health care and toothbrushing, namely: frequency of toothbrushing, dental attendance, and frequency of dental visits.

Assessed at the moment when parents complete the questionnaire.

This group of variables includes those related to the child's oral hygiene, eating behaviors, and sucking habits: frequency of toothbrushing, night-time toothbrushing, use of fluoridated toothpaste, adult supervision during toothbrushing, consumption of foods and/or drinks after night-time brushing, foods and/or drinks consumed after night-time brushing, frequency of consumption of cariogenic foods between main meals, frequency of fruit and/or vegetable consumption, pacifier use and thumb sucking.

Assessed at the moment when parents complete the questionnaire.

This group of variables collects information on the child's use of oral health care services: dental attendance, frequency of dental visits, information received about the child's oral health care and source of information about the child's oral health care.

Assessed at the moment when parents complete the questionnaire.

This group of variables refers to information on the child's general health status and the importance attributed to the child's general and oral health: classification of the child's general health, classification of the child's oral health status, importance of oral health for the child's general health, presence of a relevant health problem or disease and health problem or disease.

Assessed at the moment when parents complete the questionnaire.

This group of variables refers to the collection of social, economic, and demographic data from the study participants: sex, age, type of kindergarten, number of people in the household, child's cohabitants, child's nationality, parents' nationality and mother's educational level.

Assessed at the moment when parents complete the questionnaire.