Caries Status of First Permanent Molars and Their Association With Dietary and Oral Hygiene Habits Among a Group of Egyptian Children Aged 6-7 Years : A Cross Sectional Study.

First permanent molars are the earliest-erupting permanent teeth and, because they emerge without replacing a primary tooth, they are particularly susceptible to plaque accumulation and early carious lesions. As they account for a large proportion of dental caries in school-aged children, their eruption period represents a critical window for preventive interventions such as pit-and-fissure sealants.

Dental caries remains one of the most prevalent chronic diseases in childhood worldwide, with a multifactorial etiology involving diet, sugar consumption, salivary factors, fluoride exposure, and oral hygiene behavior. In Egypt, population-level data on the caries status of first permanent molars specifically - as opposed to caries in the dentition generally - remain limited.

This study will use a cross-sectional observational design conducted in the Paediatric Dentistry Department at October University for Modern Sciences and Arts (Giza, Egypt). Children aged 6-7 years who meet the eligibility criteria (healthy, no history of radiotherapy/chemotherapy, no retained primary teeth or developmental anomalies affecting the permanent dentition, no orthodontic treatment, and provision of parental informed consent) will be enrolled.

Each participating child will receive an intraoral clinical examination using a mirror and CPI probe, following WHO Oral Health Survey (2013) criteria, to assess caries status of the first permanent molars using the DMFT index and to record eruption pattern. Parents/guardians will complete a pre-tested, structured questionnaire (translated into Arabic) capturing dietary habits, tooth-brushing frequency, flossing, sweets intake, dental check-up frequency, fluoride toothpaste use, and socio-demographic variables (child's sex, number of children in the family, parental education).

Based on a previously reported FPM caries prevalence of 5.5%, a sample size of 272 children was calculated (97% confidence interval, 3% margin of error, with finite population correction, using Epi Info v7.2.5.0)