Oral Health Status, Oral Hygiene, and Behavioural Factors Among Disadvantaged Children: A Cross-Sectional Comparison...

Background/Objectives: Dental caries remains a major public health problem in childhood and disproportionately affects socioeconomically disadvantaged populations. Although toothbrushing and oral hygiene are commonly promoted as key preventive behaviours, their protective effect may be limited by structural factors such as access to dental care, fluoride exposure, and preventive services. This study aimed to compare dental caries experience, oral hygiene status, toothbrushing frequency, and sugar consumption among disadvantaged children from the Peruvian Amazon and Valencia, Spain, and to explore whether differences in hygiene behaviours were reflected in caries outcomes. Methods: An exploratory cross-sectional school-based study was conducted among 291 children aged 5-12 years attending three purposively selected schools serving socioeconomically disadvantaged communities: one rural school in the Peruvian Amazon (n = 162) and two urban schools in Valencia, Spain (n = 129). Dental caries experience was assessed using a combined global caries score derived from the dmft and DMFT (CAOD/cod) indices according to dentition type, and oral hygiene status was evaluated using the Simplified Oral Hygiene Index (OHI-S). Toothbrushing frequency and sugar consumption were collected through structured questionnaires. Group comparisons, Spearman correlation analyses, and exploratory multiple linear regression models were performed. Results: Mean global caries scores did not differ significantly between Peruvian and Spanish children (3.71 ± 2.86 vs. 4.07 ± 3.44; p = 0.596). However, severe caries experience (score ≥ 8) was more frequent among Valencian children (21.7% vs. 10.5%; p = 0.014). Peruvian children showed significantly better oral hygiene status (OHI-S-derived score: 1.25 ± 0.79 vs. 1.49 ± 0.84; p = 0.014) and higher toothbrushing frequency (p < 0.001). Frequent sugar consumption was similarly high in both groups. Within each population, poorer oral hygiene and lower toothbrushing frequency were associated with higher caries experience in bivariate analyses, although the exploratory multivariable models showed a more limited pattern of association. Conclusions: Among the participating schools, children from the Peruvian Amazon showed better oral hygiene indicators and more frequent toothbrushing than Spanish children, while no statistically significant difference in caries experience was detected. Because structural variables such as fluoride exposure, dental attendance, and access to restorative care were not directly measured, explanations involving healthcare infrastructure should be considered as candidate hypotheses to be tested in future, adequately powered and adjusted studies, rather than as confirmed mechanisms. Findings should not be generalised beyond the participating schools.