Effect of head position on cephalometric evaluation of the soft-tissue facial profile

Abstract

Objectives: During a cone beam CT scan, the patient is in an upright or supine position. This position depends on the brand and type of the scanner. The aims of this study are: (1) to investigate if the head position has an effect on cephalometric evaluation of the soft-tissue facial profile, comparing the recordings in natural head position (NHP) and supine head position (SHP) and (2) to investigate if age, gender and body mass index (BMI) are contributing factors to the effect of the head position. Methods: 90 subjects were photographed in profile both in NHP and in SHP. 12 soft-tissue angular and linear cephalometric values were calculated. Two-way random intraclass correlation coefficients were calculated to determine observer reliability. Paired t-tests and linear regression analyses were performed to investigate the differences between the head positions and the influence of age, gender and BMI. Results: Intraobserver reliability was generally high. Paired t-tests showed significant changes as a result of head positioning (p , 0.0001) in 9 of the 12 measurements. These differences were small and clinically not relevant, except for the "lower face-throat angle". Regression analysis revealed no relevant influence of age, gender and BMI. Conclusions: Cephalometric soft-tissue evaluation from a recording in SHP is generally reliable, except for the throat-chin area where a clinically relevant difference was found. The contour of the submandibular tissues in SHP causes the chin to appear more prominently. This can cause incorrect orthodontic diagnosis and treatment planning.

Three-dimensional evaluation of the relationship between jaw divergence and facial soft tissue dimensions

“…A consistent head posture is particularly important in this type of study, since stretching of the soft tissues can occur as a result of postural changes. 35 Although no specific aids (eg, mirrors) were used to position the head, it would be expected that most participants would have exhibited a NHP since this is a highly reproducible head posture. 36,37 Finally, the findings are restricted to the soft tissues of the face and may not necessarily be valid for making assumptions about the underlying skeletal pattern.…”

Longitudinal study of cephalometric soft tissue profile traits between the ages of 6 and 18 years

“…Soft tissue features can vary significantly from the dentoskeletal structure depending on individual variation or radiographic technique, 2 eg, the lips need to be in repose with the teeth in maximum intercuspation. Measuring the soft tissue profile establishes the ideal size and proportions of the nose and positions of the lips and chin, helping to quantify individual facial characteristics and norms.…”

Evaluation of diagnostic criteria for clinical assessment of anterior malar projection in relation to midface esthetics

“…As Frankfort horizontal plane has smallest variability in particular racialgroup, In our study, we have standardized patient's Lateral cephalograms and profile photographs by orienting the patient's head in the Frankfort horizontal position [9,10].…”