Overview of the Smile Arc in Students of Harapan 1 High School

Medan, in 2016

Hilda Fitria Lubis

and Kevin

Department of Orthodontics, Faculty of Dentistry,University of Sumatera Utara,

Keywords: Aesthetics, Mini aesthetic, Smile arc, High school students.

Abstract: Introduction: In orthodontics, the type of malocclusion that is often complaint by patients are anterior teeth

crowding and protrusive teeth which subsequently, affects facial aesthetics. Facial aesthetics is affected by

the smile arc of an individual which is distinct in every individual. One of the smile forming components in

the frontal aspect is the smile arc. There are three possible smile arcs that are commonly found in individuals;

curved, straight and reversed smile arc. Objective: The aim of this study is to determine the overview of the

smile arc among Harapan 1 Medan high school students in 2016. Materials and Methods: This was a

descriptive study with a cross sectional approach and simple random sampling method was used to select

Harapan 1 Medan high school students with a total sample of 126 students. The obtained data was analysed

using descriptive statistics. Results: The most dominant type of smile arc among Harapan 1 high school

students was the curved smile arc and there were no significant differences between males and females. The

distribution of the smile arc type obtained were 69.84% curved, 22.22% straight, and 7.94% reversed.

Conclusion: The average smile arc type of Harapan 1 Medan high school students was the curved smile.

1 INTRODUCTION

Malocclusion can disrupt the appearance of

individuals and thereby affect facial aesthetics

subjectively. In orthodontics, the type of

malocclusion that is often complaint by patients are

anterior teeth crowding and protrusive teeth. These

cases are directly related to the aesthetic aspect that

affects the appearance of the patients’ face (Dewi,

2008).

Facial aesthetic factors are influenced by the smile

arc of an individual which is different in every

individual (Dewi, 2008; Gill 2008). According to

Sarver, aesthetics in orthodontics is divided into three

categories i.e. macro aesthetics (full face), mini

aesthetics (smile), and micro-aesthetics (dental and

gingival) (Camara, 2010).

Mini aesthetics is defined as the smile aesthetic

which includes changes in facial expression involving

the eye, as well as the lifting curvature of the lips and

the muscles around the mouth. There are two basic

types of smile; the social smile (posed smile) and the

spontaneous smile (unposed smile) (Al-Johany et al.,

2011). Sabri stated that the smile forming component

in the frontal aspect consists of several factors; lip

line, smile arc, and the buccal corridor (Al-Johany et

al., 2011; Sabri, 2005).

Smile arc is the relationship between the occlusal/

incisal plane of the upper anterior teeth with the lower

lip during smiling (Sianita, 2015). Machado’s

research showed that individuals with a curved smile

tend to look younger and more confident, while the

flattened or inverted smile arc caused the individual

to look older and less attractive (Rodrigues et al.,

2009; Zaib and Hameed, 2009).

The inclination of the anterior teeth that is less

convex causes the smile to become less curved,

resulting in a flat or reversed smile arc (Machado

2014; Rodrigues et al. 2009).The shape of the dental

arc should match the curvature of the lower lip to

obtain the best appearance. This condition can be

observed in individuals with a curved smile arc (Gill,

2008; Singla and Lehl, 2014). Incisal edges of the

maxillary teeth should be parallel to the lower lip

curvature to produce a curved smile arc (Cobourne

and DiBiase, 2010; Singla and Lehl, 2014). Many

individuals prefer the curved smile arc and believe

that the straight smile arc will reduce the beauty of the

smile in men and women (Ritter et al., 2006).

According to Rice in 1996, adolescence is a

period in which an individual grows into an adult or

Lubis, H. and Kevin, .

Overview of the Smile Arc in Students of Harapan 1 High School Medan, in 2016.

DOI: 10.5220/0010067303990402

In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages

399-402

ISBN: 978-989-758-449-7

399

develop towards biological, cognitive, and

socioemotional maturity (Sabri, 2005; Sianita, 2015).

High school students are categorized as late teens as

it is in the age range of 15-20 years (Dewi, 2008). The

use of orthodontic devices among high school

students or late teens had been increasing due to

indication or aesthetic reasons (Camara, 2010). This

research is expected to provide an overview of the

aesthetic smile arc in normal Angle Class I molar

occlusion.

2 MATERIALS AND METHODS

This was a descriptive study with a cross sectional

approach to study the smile arc among Harapan 1

Medan high school students in 2016. The sample size

was determined by using the population proportion

interpretation formula with absolute accuracy.

Through this method, the minimal sample size was

obtained with an absolute precision required to

determine the proportion of individuals with specific

characteristics in a population. Furthermore, the

estimated sample size was calculated based on the

sample proportion of a previous study with a similar

methodology to this study which was 81,69%

(P=0,8169).

Based on the calculation, the subjects for this

study were 126 students with several inclusion

criteria, such as: the high school students of Harapan

1 Medan aged ≥ 15 years, no dental abnormalities, no

history of orthodontic treatment, complete permanent

dentition (up to M2), Angle Class I molar

relationship, normal overjet and overbite (2-4 mm,

measured with a caliper and ruler) and presence of

mild crowding ≤ 2 mm (measured with a caliper and

ruler).

Subjects were instructed to pose a social smile by

saying "cheese" for a period of time (± 3 seconds).

Photographs were taken three times with a Fuji S1500

camera and the best photos that fit the criterias were

selected. After collecting the photograph, the photo

was then analyzed with the Adobe Photoshop CS3

program to create the smile arc using dotted line. The

observed component was the smile arc. The photo

observation was conducted using Machado method

by drawing a line from the highest point of the 1st

region canine cusp to the 2nd region canine cusp.

The obtained data was analyzed using descriptive

statistics to evaluate the frequency and percentage of

the various smile arcs among Harapan 1 High School

students.

Before conducting this research, ethical approval

was obtained from the University of North Sumatera

Health Research Ethics Committee.

Figure 1: Types of smile arc: (A) curved smile arc, (B)

straight smile arc, and (C) reversed smile arc (Singla and

Lehl, 2014). Info: blue dotted line represents the smile arc,

yellow dotted line represents the low lip line.

3 RESULTS

The results of the analysis of the photographs,

were as follows:

Table 1: Distribution of the smile arc in high school

students of Harapan 1 Medan.

Numb

er.

Type of smile

arc

Amount

(n=126)

Percentage

(%)

1. Curved 88 69.84

2. Straight 28 22.22

3. Reversed 10 7.94

Table 2: Distribution of the smile arc based on gender in

high school students of Harapan 1 Medan.

Num

ber

Type of

smile arc

Male Female

Amount

(n= 63)

Percenta

(%)

Amount

(n= 63)

Percenta

ge (%)

1. Curved 31 49.21 57 90. 47

2. Sraight 23 36.51 5 7.94

3. Reversed 9 14.28 1 1.59

Curved smile arc type presents the highest

percentage in males (49.21%) and in females

(90.47%) followed by straight smile arc type in males

(36.51%) and females (7.94%). Type of smile arc

with the smallest percentage was the reversed smile

arc in males (14.28%) and females (1.59%).

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

400

4 DISCUSSION

Smile is an important expression in emphasizing

an attractive facial feature. An attractive or delightful

smile can make an individual more confident in

his/her social environmental (Singla and Lehl, 2014).

Creating an attractive and delightful smile involves a

harmonious relationship between the teeth, gingiva,

and lips (Sachdeva et al., 2012). An attractive and

balanced smile is one of the main goals of orthodontic

treatment, mainly due to the increased awareness of

the importance in having an attractive smile among

teenagers (Singla and Lehl, 2014). Smile analysis and

smile design has become a key element in diagnosis

and orthodontic treatment planning since the last

decade (Sachdeva, et al. 2012).

The results of this study showed that the most

common type of smile arc found among students was

the curved smile arc (69.84%) and the second highest

was the straight smile arc 22.22% (Table 1). The

results of this study was similar to the research

conducted by GC Cruz which presents curved smile

arc found in 94,4% males and females and non curved

smile arc in 5.6% of the population (Cruz, Lopez and

Rodriguez, 2015). Research by Ridal in Gowa

presents 47.2% with a curved smile arc (Ridal, 2014).

Mahfouz MN conducted a study on Palestine

adolescents aged 12-17 years, and found 75.8% had a

curved smile arc (Mahfouz, Hussein and Dogan,

2009). Furthermore, a study by Parekh H, in India

found curved smile arc in 72% females, and 62%

males (Parekh et al., 2013).

Smile arc of Harapan 1 Medan high school

students based on gender was the curved smile arc in

49.21% of male students and 90.47% of female

students followed by the straight smile arc in 36.51%

male students and 7.94% female students while the

reversed smile arc was found in 14.28% male students

and 1.59% female students (Table 2). This result was

similar to the research of Sabri and Balani, which

stated that the curved smile arc was more likely to be

found in women than men (Sabri, 2005). Overall,

45,6% male students of Harapan 1 Medan high school

tend to have a curved smile arc, followed by straight

smile arc of 36.51%, and reversed smile arc of

14.28%.

The shape of every individuals’ smile arc is

different and is influenced by the shape of the

maxillary arc (Camara, 2010). The maxillary arc of

the subjects, especially at the anterior region, greatly

affects the curvature of the smile arc. The wider the

maxillary arc, the smaller the curvature of the anterior

region, hence creating a more straighter smile (Sabri,

2005). 69.84% of the research subjects had the curved

smile arc type, thus they were categorized as having

the ideal smile. One substantial factor that may had

influence the high number of curved smile arc among

subjects in this study was probably due to the tilting

of the maxillary occlusal plane in relation to the

Frankfort plane, as this would had increased incisor

display and tend to produce a curved smile (Bahirrah

and Sitorus, 2015). Furthermore, the study by Sabri

stated that the smile arc in women were found to be

more convex compared to men due to differences in

the development of the facial musculature (Sabri,

2005).

5 CONCLUSION

The most dominant smile arc type in high school

students of Harapan 1 Medan was the curved smile

arc. The distribution of smile arc type was 69.84%

curved, 22.22% straight, and 7.94% reversed.

ACKNOWLEDGEMENTS

The authors would like to express our appreciation to

the University of Sumatera Utara for providing their

fund for this research.

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