Natural head position: key position for radiographic and photographic analysis and research of craniofacial complex

Abstract

The Frankfort horizontal is a useful compromise for studying skulls but not for orienting the natural head position (NHP) in the living because it is normally distributed around a true extracranial horizontal. Nonetheless, orthodontists dealing with living subjects, rather than inert crania, have used this Frankfort horizontal faithfully in cephalometry. Because the cant or inclination of all intracranial reference lines is subjected to biologic variation, they are unsuitable for meaningful cephalometric analysis. Registration of head posture in its natural position has the advantage that an extracranial vertical or a horizontal perpendicular to that vertical can be used as reference line for cephalometric analysis. Purpose of this paper is to provide an updated review of various methods to reproduce and record the NHP.

A CBCT evaluation of molar uprighting by conventional versus microimplant-assisted methods: an in-vivo study

“…This was done in order to maintain standardization of all patients. The literature 4 suggests that the reproducibility of NHP is close to 2 o on repeated radiographs. NHP is a reproducible position when used for bidimensional radiography, the subject is expected to exhibit same reproducibility in position when taking 3D scans.…”

“…To confirm the reliability of the plane, 3 the distance from the plane to the center of the mini-implant on both pre and post scans was calculated. 4 As these measurements were standardized, the plane was used for extrusive measurements. The center of resistance was marked for the second molar at the level of the furcation, a perpendicular reference line was drawn 5 and the vertical distance from the center of resistance of the molar to the constructed plane was calculated.…”

Natural Head Postures of Patients With Facial Asymmetry in Frontal View Are Corrected After Orthognathic Surgeries

“…23 Even though recent studies have described the concept of NHP as a small range of positions oscillating around a mean posture, NHP has been used as a key reference position of photographic and radiographic analysis, and for treatment planning for orthognathic patients. 23,24 However, several studies documented that NHP can be changed antero-posteriorly in the lateral view due to orthognathic surgery. [12][13][14][15][16][17] In this study, IP horizontal angles measured in the frontal view was used to compare NHPs of FA and FS groups.…”

Artefacts in lateral cephalometric radiography

“…Hastanın, gözü seviyesinde uzak bir noktaya baktığı, örneğin; kumsalda gün batımını izlerken meydana gelen baş pozisyonu 'doğal baş konumu' olarak adlandırılır. 9 Doğal baş konumu kavramı, ortodontide 1958 yılında çeşitli araştırmacılar tarafından kullanılmaya başlamıştır. 10,11. Cooke ve Wei, 1998 yılında doğal baş konumunun 2 ye yakın farkla radyograflarda tekrarlanabileceğinden bahsetmişlerdir.…”