A proposal of 3-dimensional assessment of face with CBCT images : a pilot study of facial analysis with 'anterior facial pyramid'

Abstract

Objectives

The aim of this study was to suggest a new reference frame concerning the zygoma area for the soft tissue analysis of lower face. The average relationship between the new frame and the facial landmarks in skeletal Class I patients was studied by using the CBCT records of Korean young adults.

Materials and methods

Anterior facial pyramid (AFP) was designed for evaluating the anterior facial profile on total 48 CBCT images (23 male and 25 female) in this study. AFP was composed of 4 soft tissue landmarks, which were pronasale, right zygomatic point, left zygomatic point, and soft tissue pogonion. The samples were classified into two groups by gender. The linear and angular measurements of AFP, nose, and lip were performed. The relationship between AFP and the landmarks of nose and lip was assessed.

Results

The zygomatic point was posteriorly located to N’-perpendicular plane (N’-per.). as much as 14.4 ±2.56 mm in men and 12.1±2.26 mm in women (p < 0.01). The pronasale was protruded to N’-per. as much as 22.5±2.55 mm in men and 20.4±2.36 mm in women (p < 0.05). The midface angle transverse was 114.4±3.61 degree in men and 118.6±4.48 degree in women (p < 0.01). The ratio of the height of base of AFP to the midface width was 64.4±5.68 % in men and 62.3±5.07 % in women (p > 0.05). The cheilion right/ left was protruded to the base as much as 1.6±2.86 mm in men and 0.1±3.04 mm in women (p > 0.05). The labiale superius right/ left was located away from the side 2.5±2.15 mm in men and 2.1±1.95 mm in women (p > 0.05). The distance between the labiale inferius right/ left and the side of AFP was 3.4±3.70 mm in men and 3.2±3.43 mm in women (p > 0.05). The upper lip point of men was protruded from anterior vertical edge (E-line) as much as 0.4±2.54 mm, the upper lip point of women was posteriorly positioned to the anterior vertical edge as much as 1.2±1.98 mm (p < 0.05). The lower lip point of men was protruded from the anterior vertical edge as much as 1.7±2.82 mm in men and 1.0±2.21 mm in women (p > 0.05).

Conclusions

A new facial reference frame concerning zygoma, anterior facial pyramid (AFP), was proposed for the 3-dimensional assessment of face. The average relationship between the new frame and its contents was studied. This study may be fundamental to the 3-dimensional assessment of the lip concerning zygoma when planning orthodontic treatment.