Korean J Orthod.  2017 Mar;47(2):100-107. 10.4041/kjod.2017.47.2.100.

Smile esthetics: Evaluation of long-term changes in the transverse dimension

• Akyalcin S
• Misner K
• English JD
• Alexander
• Alexander
• Gallerano

• KMID: 2400387
• DOI: http://doi.org/10.4041/kjod.2017.47.2.100

Abstract

OBJECTIVE
To analyze the long-term changes in maxillary arch widths and buccal corridor ratios in orthodontic patients treated with and without premolar extractions.
METHODS
The study included 53 patients who were divided into the extraction (n = 28) and nonextraction (n = 25) groups. These patients had complete orthodontic records from the pretreatment (T1), posttreatment (T2), and postretention (T3) periods. Their mean retention and postretention times were 4 years 2 months and 17 years 8 months, respectively. Dental models and smiling photographs from all three periods were digitized to compare the changes in three dental arch width measurements and three buccal corridor ratios over time between the extraction and nonextraction groups. Data were analyzed using analysis of variance tests. Post-hoc multiple comparisons were made using Bonferroni correction.
RESULTS
Soft-tissue extension during smiling increased with age in both groups. The maximum dental width to smile width ratio (MDW/SW) also showed a favorable increase with treatment in both groups (p < 0.05), and remained virtually stable at T3 (p > 0.05). According to the MDW/SW ratio, the mean difference in the buccal corridor space of the two groups was 2.4 ± 0.2% at T3. Additionally, no significant group × time interaction was found for any of the buccal corridor ratios studied.
CONCLUSIONS
Premolar extractions did not negatively affect transverse maxillary arch widths and buccal corridor ratios. The long-term outcome of orthodontic treatment was comparable between the study groups.

Keyword

Esthetics; Stability; Extraction

MeSH Terms

Bicuspid
Dental Arch
Dental Models
Esthetics*
Humans
Smiling

Figure

• 

  Figure 1 Maxillary arch width measurements used in this study. ICW, Intercanine width; IPW, interpremolar width; IMW, intermolar width.

• 

  Figure 2 Linear measurements made on smile photographs. SW, Smile width; MDW, maximum dental width; ICW, intercanine width.

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  Figure 3 Group × time interactions for the maxillary arch width measurements of the extraction (black line) and nonextraction (gray line) groups. ICW, Intercanine width; IPW, interpremolar width; IMW, intermolar width.

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  Figure 4 Group × time interactions for the buccal corridor ratios of the extraction (black line) and nonextraction (gray line) groups. ICW, Intercanine width; SW, smile width; MDW, maximum dental width.

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