title: Reproducibility of natural head position in normal Chinese people.
abstract: BACKGROUND
  In this study, we evaluated the reproducibility of natural head position for pitch and roll acquired using 3 methods.
  
  
  METHODS
  The participants were 30 Chinese adults (ages, 23-28 years) who had normal occlusion with no history of orthodontic therapy, maxillofacial trauma, or surgery. The natural head position was acquired using the self-balanced, mirror, and estimated positions, which were performed in duplicate and repeated after 1 week. Three-dimensional photographs were recorded with a horizontal laser line projected onto the face. The laser lines were observed by registering the repeated 3-dimensional photographs. The roll and pitch of the head orientation were measured with a digital ruler. Reproducibility was calculated using Dahlberg's formula and the Bland-Altman method.
  
  
  RESULTS
  The reproducibility values calculated with Dahlberg's formula were 1.51°, 1.2°, and 0.99° for pitch, and 0.78°, 0.76°, and 0.41° for roll in the self-balanced, mirror, and estimated positions, respectively.
  
  
  CONCLUSIONS
  The 3 methods are reproducible for both pitch and roll, and the estimated position showed the best reproducibility among these methods. This indicates that the estimated position could be used for acquiring the reference plane in preoperative planning for orthognathic surgery.
authors: Resident, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors: Kaiyue
authors: K
authors: Tian
authors: Assistant engineer, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors: Qianqian
authors: Q
authors: Li
authors: Associate professor, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors: Xiaoxia
authors: X
authors: Wang
authors: Associate chief physician, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors: Xiaojing
authors: X
authors: Liu
authors: Professor, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors: Xing
authors: X
authors: Wang
authors: Associate professor, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China. Electronic address: kqlzl@sina.com.
authors: Zili
authors: Z
authors: Li
mesh_terms: D000328:Adult; D005260:Female; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007834:Lasers; D008297:Male; D010781:Photography / Q000379:methods; D011187:Posture; D015203:Reproducibility of Results; D055815:Young Adult