Abstract To describe cervical bone mineral density (BMD) in children and adolescents using Cone-beam Computed Tomography (CBCT) combined with K2HPO4 liquid phantoms. Children and adolescents aged 7–19 years who underwent CBCT for orthodontic treatment in our imaging department between January 2023 and June 2023 were selected. The CT values of the second (C2) and third (C3) cervical vertebrae were measured using the software supplied with the CBCT. K2HPO4 liquid phantoms were prepared according to standard protocols and scanned monthly. Regression equations were established between BMD values and CT values. The BMD values of C2 and C3 were then calculated and subsequently analyzed. A total of 455 children and adolescents participated in the study. The BMD values for females were found to be significantly higher than those for males across all age groups (P 0.05). The results of this study provide reference values for BMD of C2 and C3 using CBCT combined with liquid phantoms. These reference values, obtained from healthy individuals, enable the assessment of BMD for systemic bone metabolism, orthodontics, implants, and tooth extraction, providing significant economic and social benefits.