Primary dentition arch form in children aged 3–6 years: a multicenter study

To investigate the age, gender, and regional differences in dental arch dimensions of 3- to 6-year-old children with primary dentition in China, and to analyze the morphology of different dental arch types in children. A total of 449 primary dentition samples were randomly selected from children aged 3–6 years across six major regions in China. Body weight and height were measured, and body mass index (BMI) was calculated. Digital models were analyzed using Geomagic Studio 2014 to measure Characteristics of arch morphology. The included samples were grouped and compared based on age, gender, and region. Additionally, the dental arches were classified into tapered, ovoid, and square forms, and the differences in height, weight and BMI were compared. Older children presented shorter arch length (3-year-old, 19.51 mm, 6-year-old, 18.52 mm, P < 0.05). The measured values of all dental arch parameters were greater in males than in females (male: 45.37 mm, female: 43.23 mm, P < 0.05). Maxillary and mandibular arch widths were positively correlated with weight, and maxillary arch length was positively correlated with height. Compared with tapered and ovoid arches, square arches have shorter length, and their width differences gradually decrease toward the posterior region, with no significant difference in BMI. From ages 3–6, older children presented shorter arch length and slightly greater arch width. Males have larger dimensions than females. Height and weight are significantly correlated with the size and morphology of the primary dental arch. Children with square arches had shorter arch length and greater arch width.