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Whipps Cross University Hospital
NHS Trust
The Effect of Extraction and Non-extraction Orthodontic
Treatment on Smile Aesthetics in Caucasian Females
Parmjit Singh*, Margaret Collins
Results
Background
Patients seek orthodontic treatment with aesthetic
improvement as a primary goal of treatment.
Males and females scored non-extraction and extraction
smiles similarly.
Poor smile aesthetics have been associated with premolar
extraction treatment.1
Lay people and orthodontists scored similarly with higher
scored awarded to non-extraction smiles:
Extraction therapy is said to decrease smile width and
flatten profiles.
8
Score
This age old debate shows no signs of abating.
10
Aim
6
Orthodontist
Lay Person
4
2
0
To test the hypothesis that non-extraction and 4 premolar
extraction post-orthodontic female Caucasian patient
smiles are scored equally by male and female lay people
and male and female orthodontists.
Subjects and Method
0
20
40
60
80
100
Assessment
The descriptive statistics for lay people and orthodontists are
shown below:
Group
n
minimum
maximum
mean
standard
deviation
95%
confidence
interval
50
3.20
7.80
5.93
1.12
5.61/6.25
50
3.00
7.00
5.24
1.03
4.95/5.54
50
2.40
7.60
5.33
1.24
4.98/5.68
50
2.00
7.40
4.82
1.13
4.50/5.14
Orthodontists:
The study adopted a hospital based retrospective design.
Non-extraction
5 non-extraction and 5 extraction subjects were selected
from cases previously used for the MSc and MOrth
examinations.
Extraction
A standardised smile photograph was taken.2
Extraction
Lay People:
Non-extraction
The non-extraction smiles are shown in the left column and
the extraction smiles in the right column below:
Non-extraction smiles were scored more favourably than
extraction smiles by both lay people (p<0.01) and
orthodontists (p<0.03).
The photographs were
inserted into a photo album.
This difference was attributed mainly to lip position, tooth
alignment, tooth colour and tooth shape.
100 assessors were recruited
comprising 50 lay people and
50 orthodontists.
Few made reference to the broadness of the smile or
buccal corridor space.3
Each group was made up
of 25 male and 25 female
assessors.
Assessors were asked to
familiarise themselves
with the photographs in
the album.
A questionnaire was then completed by going through the
album again using a visual analogue scale:
0
1
2
3
Very unattractive
4
5
6
7
8
9
10
Very attractive
Assessors were finally asked to name the factor that most
influenced their scores.
Smile scores were analysed using a Univariate Analysis of
Variance.
Using 10 assessors, the reproducibility of the smile scores was
evaluated with a Wilcoxin Signed Rank Test and no
significant difference was found.
Conclusions
Lay people and orthodontists awarded higher scores to
non-extraction smiles in this sample of Caucasian females.
This difference could not be attributed to the type of
treatment (non-extraction or extraction).
The alleged detrimental effects of extraction therapy should
be questioned.
References
1. Witzig JW, Spahl TJ. The clinical management of basic
maxillofacial orthopaedic appliances. Littleton (Mass),
1987: PSG Publishing Company.
2. Trumble A. A brief history of the smile. New York, 2004:
Basic Books
3. Frush JP, Fisher RD. The dynesthetic interpretation of the
dentogenic concept. J Pros Dent 1958; 8: 558-581.
*Contact details: [email protected]