Methods: In this longitudinal study, 58 adolescents (29 females and 29 males) with normal occlusion were selected from the archive of Qazvin dental school. The lateral cephalograms which had been taken in natural head position (by using a mirror and looking at their own eyes) were traced and 12 angular and linear measurements of the head and neck posture were calculated during two years. The changes of head and neck posture were analyzed separately in male and female individuals and statistically assessed by paired t test.
Results: Head and neck posture measurements showed a significant change in females but insignificant in male adolescents during 2 years. Angular measurements between cranial base (SN) and true vertical line showed a significant increase in females (p=0.002) as well as measurements between cervical spine and true horizontal line (p=0.008). But the measurements between cervical spine and skull remain almost steady during two years of growth.
Conclusion: These findings suggest neither flexion nor extension happened in this period of growth but there was a clockwise rotation of head and neck as a whole without altering their angulation to each other. It could be explained by increasing mandibular length and subsequent forward shift of center of gravity of skull.
Keywords: Natural Head Position (NHP), Adolescent, Cephalometry, Growth.