Reliability of measuring facial morphology with a 3-dimensional laser scanning system

doi:10.1016/j.ajodo.2004.06.037

American Journal of Orthodontics and Dentofacial Orthopedics

Volume 128, Issue 4, October 2005, Pages 424-430

https://doi.org/10.1016/j.ajodo.2004.06.037 Get rights and content

Introduction: The purpose of this prospective clinical trial was to evaluate the reliability of a 3-dimensional facial scanning technique for the measurement of facial morphology. Methods: A field study was conducted in 2 comprehensive schools in the South Wales region of the United Kingdom. Forty subjects, mean age 11 years 3 months, were analyzed for soft tissue changes at baseline (T1), within 3 minutes (T2), and 3 days later (T3) by using 2 commercially available Minolta Vivid 900 (Osaka, Japan) laser-scanning devices assembled as a stereo pair. Left and right images were merged to form the whole face, and these images were superimposed to assess the errors at T1 and T2, and T1 and T3. Results: The results showed that premerged left and right mean shell deviations were 0.38 ± 0.14 mm for scans at T1, 0.31 ± 0.09 mm at T2, and 0.34 ± 0.12 mm at T3. The mean differences of the merged composite face were 0.31 ± 0.08 mm between T1 and T2, and 0.40 ± 0.11 mm between T1 and T3. Paired t tests showed no significant difference between these groups (P > .05). Shell deviation facial maps of the merged scans showed that 90% of the created composite facial scans were within an error of 0.85 mm. Conclusions: Capturing the soft tissue morphology of the face with this technique is clinically reproducible within 3 minutes and 3 days of the initial records.

Section snippets

Subjects and methods

A cohort of 11-year-old children from 2 large schools in South Wales was invited to participate in a longitudinal growth study. Forty randomly selected subjects (21 boys and 19 girls, mean age 11 years 3 months) were chosen to participate in the study.

Approval was obtained from the directors of education, head teachers, school committees, and the relevant ethics committee. In addition, written consent from parents was required for the child to be included in the growth study.

The laser scanning

Results

The mean shell deviation of the left and right scans before merging for time intervals T1 and T2, and T1 and T3, are shown in Table I. The mean shell deviations between scan times were 0.38 ± 0.14 mm for T1, 0.32 ± 0.80 mm at T2, and 0.34 ± 0.12 mm at T3. Each of these data sets was tested for normality and found to be normally distributed. Paired t tests were carried out on the mean shell deviations between T1 and T2 (P = .74) and T1 and T3 (P = .65). The results showed no significant

Discussion

Most studies have concentrated on reliably measuring distances between chosen anthropometric points on the 3D-generated images against corresponding points on live subjects6, 24, 25, 26 as a form of validation. Some studies use complex mathematics to derive and analyze shapes.27, 28 Recently, attempts have been made to analyze the dynamic face by linear measurement between points²⁹ and facial polygons.³⁰

Error studies to measure accurate facial soft tissue reproducibility are rare. Only one

Conclusions

This study has confirmed that the laser scanning system used to capture facial morphology is reliable over 3 minutes and 3 days. It also provides the foundation for laser scanning to be used as a measurement tool for craniofacial imaging. The following conclusions can be made:

1
3D imaging can be reliably undertaken in a school setting.
2
The error of the system in aligning left and right facial scans is 0.13 ± 0.18 mm.
3
The mean shell deviations in superimposition of whole faces were 0.31 ± 0.08 mm

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The Minolta Vivid range are the most common laser-based scanners applied for medical facial assessment in the literature. Kau et al. 51 evaluated the precision of the Minolta Vivid 900 scanner by comparing scans of identical patients at baseline, 3 min, and 3 days and found no statistically significant discrepancies. A large number of sample points allow laser-based triangulation scanners to theoretically collect highly accurate data.
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^a: Clinical lecturer in orthodontics.

^b: Professor and department head.

^c: EPRSC research fellow.

^d: Senior lecturer and consultant in orthodontics.

^e: Senior lecturer and consultant in dental public health.

^f: Head of visual aids department.

^g: Lecturer in statistics and epidemiology.

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Original articleReliability of measuring facial morphology with a 3-dimensional laser scanning system

Section snippets

Subjects and methods

Results

Discussion

Conclusions

Br J Oral Maxillofac Surg

J Craniomaxillofac Surg

Br J Oral Maxillofac Surg

Am J Orthod Dentofacial Orthop

Am J Orthod Dentofacial Orthop

J Dent

Br J Plast Surg

Br J Plast Surg

Current status and future needs in craniofacial imaging

Orthod Craniofac Res

Craniofacial imaging in orthodonticshistorical perspective, current status, and future developments

Angle Orthod

The investigation of the changing facial appearance of identical twins employing a three-dimensional imaging system

Orthod Craniofac Res

Three-dimensional analysis of facial morphology in normal Japanese children as control data for cleft surgery

Cleft Palate Craniofac J

Three-dimensional facial growth studied by optical surface scanning

J Orthod

Three-dimensional modeling for modern diagnosis and planning in maxillofacial surgery

Int J Adult Orthod Orthog Surg

Assessment of facial tissue expansion with three-dimensional digitizer scanning

J Craniofac Surg

Original article
Reliability of measuring facial morphology with a 3-dimensional laser scanning system