Sagittal changes in the dens significantly slowed after 12 years of age.

Introduction: The odontoid process is an important component of the upper cervical, and the process of ossification for odontoid does not cease completely until skeletal maturity. Research question: The aim of the study was to obtain the inclination parameters of the dens in many healthy children and to analyze the trends and variations in the inclination of the dens. Material and methods: All the CT data obtained from our hospital was reviewed for next measurement. Posterior edge of odontoid angle (PEOA), anterior edge of odontoid angle (AEOA), odontoid retroflection angle (ORA), posterior dens angulation angle (PDAA), screw insertion angle (SIA), and pB-C2 line were measured and analyzed. Results: A total of 219 patients were divided into 6 groups based on age at an interval of 3 years. The mean values of PEOA and PDAA dropped dramatically with age up to the ten to twelve-year group and then decreased slightly until 18 years old. Moreover, the AEOA and ORA declined gradually from birth to adulthood. These parameters were statistical significance within different age groups. However, the SIA was largely unchanged from birth to 18 years old and appeared to be independent of age. In contrast, the PB-C2 line has a distinguish distribution, with an increase up to the nine to twelve-year age group and then gradually decreased until 18 years old. Discussion and conclusion: The inclination of dens was constantly changing during pediatric growth, but the trends were different. These developmental changes slow down significantly after the age of 12 years.