Oral Hygiene and Dietary Behaviors Associated with Major Carious Lesions in Primary Dentition: A Cross-Sectional Study

Background/Objectives: Dental caries in primary dentition is strongly related to daily oral hygiene routines and sugar-related dietary behavior. This study assessed oral hygiene and dietary behaviors associated with the clinical severity of carious lesions in primary dentition. Methods: This observational, cross-sectional, clinical-record-based study assessed 448 pediatric dental records from children examined in Craiova, Romania. After applying predefined eligibility criteria, 400 parent–child pairs were included. Children were aged 3–6 years and had primary or early mixed dentition with predominant primary teeth. Carious lesions were classified as absent, incipient, cavitated non-complicated caries, or advanced caries with pulpal/periapical involvement. The primary analysis focused on toothbrushing onset and frequency, toothbrush and toothpaste type, night feeding duration, sweets intake, and sweetened or carbonated beverage intake. Logistic regression was used to identify factors associated with higher odds of major carious lesions. Secondary clinical-record variables were analyzed exploratorily. Results: Carious lesions were recorded in 331 children, while 69 children were caries-free. Incipient caries, cavitated non-complicated caries, and advanced caries with pulpal/periapical involvement were recorded in 99, 116, and 116 children, respectively. Child age and sex were not significantly associated with caries severity. In the adjusted model, delayed toothbrushing onset (OR = 1.464; 95% CI: 1.148–1.866; p = 0.002) and sweetened beverage consumption (OR = 2.488; 95% CI: 1.561–3.963; p < 0.0005) remained independently associated with major carious lesions after Bonferroni correction. Conclusions: In this sample, major carious lesions in primary dentition were associated mainly with modifiable postnatal behaviors, particularly delayed initiation of toothbrushing and sweetened beverage intake. Due to the cross-sectional design, the findings should be interpreted as associations, not causal relationships.