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Results. Background. Aim. Subjects and Method. Conclusions. 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.

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Subjects and Method


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

Males and females scored non-extraction and extraction smiles similarly.

Lay people and orthodontists scored similarly with higher scored awarded to non-extraction smiles:

The descriptive statistics for lay people and orthodontists are shown below:

Non-extraction smiles were scored more favourably than extraction smiles by both lay people (p<0.01) and orthodontists (p<0.03).

This difference was attributed mainly to lip position, tooth alignment, tooth colour and tooth shape.

Few made reference to the broadness of the smile or buccal corridor space.3

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.


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:

Patients seek orthodontic treatment with aesthetic improvement as a primary goal of treatment.

Poor smile aesthetics have been associated with premolar extraction treatment.1

Extraction therapy is said to decrease smile width and flatten profiles.

This age old debate shows no signs of abating.

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.

The study adopted a hospital based retrospective design.

5 non-extraction and 5 extraction subjects were selected from cases previously used for the MSc and MOrth examinations.

A standardised smile photograph was taken.2

The non-extraction smiles are shown in the left column and the extraction smiles in the right column below:

The photographs were inserted into a photo album.

100 assessors were recruited comprising 50 lay people and 50 orthodontists.

Each group was made up of 25 male and 25 female


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 4 5 6 7 8 9 10

Very unattractive 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.