Assessment of Facial Change - Cardiff University

Measuring Instruments

Assessment of Facial Change

Professor Stephen Richmond, Cardiff University Dental School

To assess facial growth it is necessary to superimpose sequential images on a common three-dimensional framework with a common origin. Eight facial shells are shown aligned below illustrating incremental growth. The facial changes between ages 12 and 17 years old are highlighted in the colour map. The positive changes (highlighted by warm colours in Fig. 1) are significant above the eyebrows, nose and chin. The green colour indicates no change and the reduced prominence (highlighted by the cold colours – blue in Fig. 1) occurs below the eyes and cheek areas.

: Fig. 1

Planning and assessment of outcome for facial surgery -

" It is important to plan and evaluate surgical interventions in
three-dimentions."

The colour deviation map highlights the surface differences in facial
shells at the age of 12 and 17 years old

Pre Surgical Analysis

: Fig. 2

The surface facial texture has been captured using two Konica Minolta VI-910 laser cameras. The surface laser scan has been superimposed on the CBCT 3D reconstruction of the skeletal structures.

: Fig. 3

In order to identify the areas of facial disharmony an average facial template matched for age and gender (gray in Fig. 3) is aligned to theindividual’s face, referenced to the inner canthal plane.

The superimposition clearly highlights a mid-face insufficiency and the lower lip appears to be prominent.

: Fig. 4

The colour deviation map highlights the detail of discrepancies.

The cheeks have circular deficiencies of 4.9 mm on the left and 5.3 mm on the right that gradually degrade to within 0.5 mm just below the eyes. The map suggests that the chin is not far from the normal range. The lower lip is prominent (4.8 mm).

: Fig. 5

As the individuals face is long by 4mm it was planned to undertake a bimaxillary procedure. The maxilla and mandible were removed from the computerized model just leaving the cranial base. This procedure was undertaken using Geomagic 7

: Fig. 6

A Le fort 1 was proposed to move the maxilla upward 4mm and forward by 5 mm. Recent dental casts were scanned using the VI-900 laser cameras and the 3D dental cast was superimposed on the maxillary dentition (fit accurate <0.3 mm). The reflected oral mucosa can be clearly seen anterior to the maxilla.

: Fig. 7

The upper and lower dental casts were scanned in best-fit occlusion and then superimposed on the maxillary dentition.

: Fig. 8

A sagittal split was performed, the anterior part of the mandible was aligned and fitted to the mandibular dental cast and the posterior fragment left in it’s original position.

Post Surgical 3 Month Analysis

: Fig. 9

The individual surface laser scan was repeated and aligned and fitted to original the facial surface and planned surgical skeletal movements.

: Fig. 10

The relationship of the surface soft tissues and underlying skeletal structures are shown in Fig. 9 & 10, at 3 months with more favourable soft tissue and skeletal relationships. Some residual swelling is clearly seen lower mid-face.

Post Surgical 6 Month Analysis

: Fig. 11

: Fig. 12

The individual returned 6 months after the surgery had taken place, at this point the surface scan was repeated. A significant amount of post-operative swelling has diminished. The colour map based on differences between pre surgical and 6 months post-surgery are highlighted in Fig. 11 & 12. A significant improvement in the mid-face is highlighted (yellow-orange). The mandibular retraction is highlighted (blue). The various movements are indicated at 6 months with support to the alar based by 4-5mm. The mandible has been retracted by 7-8mm. The retraction of the mandible is probably larger than ideal mainly resulting from the desire to achieve a good Class I dental interdigitation.