Digital videographic measurement of tooth display and lip position in smiling and speech: reliability and clinical application.
BACKGROUND
Tooth display and lip position in smiling and speech are important esthetic aspects in orthodontics and dentofacial surgery. The spontaneous smile and speech are considered valuable diagnostic criteria in addition to the posed social smile. A method was developed to measure tooth display in both smile types and speech.


METHODS
The faces of 20 subjects were individually filmed. Spontaneous smiles were elicited by a comical movie. The dynamics of the spontaneous smile were captured twice with a digital video camera, transferred to a computer, and analyzed on videoframe level. Two raters were involved. Posed social smiles and speech records were also included. Reliability was established by means of the generalizability theory. It incorporated rater, replication, and selection facets.


RESULTS
Generalizability coefficients ranged from .99 for anterior teeth to .80 for posterior teeth. The main sources of error were associated with rater and selection facets. The replication facet was a minor source of error.


CONCLUSIONS
This videographic method is reliable for measurement of tooth display and lip position in spontaneous and posed smiling and speaking. Application of the method is warranted especially when obtaining an emotional smile is difficult, such as cleft lip and palate or disfigured patients.
van der Geld
Pieter A A M
PA
Department of Orthodontics and Oral Biology and Cleft Palate Craniofacial Unit, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. p.vd.geld@planet.nl
Oosterveld
Paul
P
van Waas
Marinus A J
MA
Kuijpers-Jagtman
Anne Marie
AM
D000328:Adult; D004955:Esthetics, Dental / Q000523:psychology*; D005881:Gingiva / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012904:Smiling / Q000523:psychology*; D013060:Speech; D014070:Tooth / Q000033:anatomy & histology*; D014743:Videotape Recording