Korean J Orthod.  2017 Jan;47(1):31-38. 10.4041/kjod.2017.47.1.31.

Factors affecting smile esthetics in adults with different types of anterior overjet malocclusion

• Cheng HC
• Cheng PC

• KMID: 2392194
• DOI: http://doi.org/10.4041/kjod.2017.47.1.31

Abstract

OBJECTIVE
This study aimed to quantitatively assess the relationship of smile esthetic variables with various types of malocclusion, and identify the cephalometric factors affecting smile measurements.
METHODS
This retrospective study included 106 patients who were treated with retention at the orthodontic department of Taipei Medical University Hospital. Hard-tissue variables were measured using lateral cephalographic tracings, and nine smile esthetic variables were measured using facial photographs. The patients were divided into three groups according to their overjet (< 0, 0-4, and > 4 mm). An analysis of variance was conducted to compare the pretreatment cephalometric variables and smile esthetic variables among the three groups. Multiple linear regression analysis was performed to identify the cephalometric factors affecting the smile measurements in each group.
RESULTS
Except the upper midline and buccal corridor ratio, all of the smile measurements differed significantly among the three groups before orthodontic treatment. Some of the smile characteristics were correlated with the cephalometric measurements in different types of malocclusion. The overjet was the major factor influencing the smile pattern in all three types of malocclusion.
CONCLUSIONS
Smile characteristics differ between different types of malocclusion; the smile may be influenced by skeletal pattern, dental procumbency, or facial type. These findings indicate that establishment of an optimal horizontal anterior teeth relationship is the key to improving the smile characteristics in different types of malocclusion.

Keyword

Smile; Esthetics; Malocclusion; Soft tissue

MeSH Terms

Adult*
Esthetics*
Humans
Linear Models
Malocclusion*
Retrospective Studies
Tooth

Figure

• 

  Figure 1 Cephalometric landmarks and skeletal, dental, and soft tissue variables used in this study.SNA, Sella-Nasion-Point A angle; SNB, Sella-Nasion-Point B angle; ANB, Point A-Nasion-Point B angle; SN-GoGn, mandibular plane angle to the anterior cranial base; FMA, Frankfort horizontal plane to mandibular plane angle; U1-NA (°), upper incisor inclination to Nasion-Point A; U1-NA (mm), distance from upper incisor to NA line; L1-NB (°), lower incisor inclination to Nasion-Point B; L1-NB (mm), distance from lower incisor to NB line; U1-L1, angle between upper and lower incisor inclination; U1-PP, distance from upper incisor to palatal plane (ANS-PNS); IMPA, lower incisor-mandibular plane angle; UFH/LFH, the proportion of upper facial height to lower facial height; PFH/AFH, the proportion of posterior facial height to anterior facial height.

• 

  Figure 2 Smile measurements. A, Arc ratio; B, upper lip height; C, upper midline; D, buccal corridor ratio; E, smile index; F, archform index; G, lower teeth exposure; and H, interlabial gap.

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