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Volume 71, No.1: 2019 Siriraj Medical Journal www.smj.si.mahidol.ac.th
168
Basel Mahardawi, B.D.S.*, Teeranut Chaisamut, D.D.S.*, Natthamet Wongsirichat, B.Sc., D.D.S.*,**
*Department of Oral Maxillofacial Surgery, Faculty of Dentistry, Mahidol University, Bangkok 10400, **Walailak University International College of
Dentistry, Bangkok 10400, ailand.
Gummy Smile: A Review of Etiology,
Manifestations, and Treatment
Corresponding author: Natthamet Wongsirichat
E-mail: natthamet.won@mahidol.ac.th
Received 25 August 2018 Revised 6 December 2018 Accepted 24 December 2018
ORCID ID: http://orcid.org/0000-0003-3005-2680
http://dx.doi.org/10.33192/Smj.2019.26
ABSTRACT
Excessive gingival display, or what is known as Gummy Smile, is a clinical condition which is attracting a great
attention and focus recently. Having knowledge and background about the cause and the treatment of each case of
excessive gingival display is essential for making the accurate diagnosis and performing the correct procedure. is
article reviews the most common causes of excessive gingival display, manifestations of this condition, and some
of the important treatment options for Gummy Smile. In addition, the article also puts the light on some points
regarding the accepted measurement in several studies, and considers the prediction planning for Gummy Smile
associated with a skeletal etiology.
Keywords: Excessive gingival display; gummy smile; vertical maxillary excess (Siriraj Med J 2019;71: 168-174)
INTRODUCTION
A wonderful smile is an essential feature of beauty to
which society gives an increasing importance currently.
e concept of a nice smile basically depends on the
entity of three anatomic components: gum, teeth, and
lips.1 In the meantime, an increasing awareness regarding
beauty and physical appearance has become a motivation
for every clinician to evaluate the important aspects of
patient’s smile and link the dynamic relationship between
the teeth, gingiva, and lips together when smiling.2
e gingiva is a crucial aspect to be considered in
the esthetics of smiling1, in which the upper lip should
be elevated around 80% of its normal length, exposing
teeth and gingiva.3 Sharma et al.,2 dened the normal
gingival display as the gum exposure between the inferior
border of upper lip and gingival margin of anterior central
incisors when smiling. An exposure of gingiva around 0-2
mm when smiling, and 2-4 mm of the maxillary incisor
edges when the lips are at the rest state are considered as
acceptable. While more than 2 mm of gingival exposure
when a person smiles is stated by experts as an excessive
gingival display, or what is known as “Gummy Smile”,4
which is more of a descriptive term than a diagnosed
condition, and aects a notable proportion of the population,
especially women who are aected more than men.5
Maxillary excess both vertically and anterioposteriorly
(Bimaxillary protrusion), hyper mobility of the upper
lip due to hyper function of labial elevator muscles, and
excessive gingival display associated with altered passive
eruption are the three major causes of this condition.6
In addition to the stated reasons, medications, dental
plaque, hereditary and incompetent lip can also result
in abnormal gingival display.5
For adults, improved aesthetic outcomes are becoming
increasingly essential in these procedures to the point
where some patients are pursuing only the esthetic side,
Mahardawi et al.
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Review Article SMJ
not a functional benet.7 erefore, nding an eective
treatment for each cause of the gummy smile is a must.
Etiologies of gummy smile:
Many studies have stated the main causes of excessive
gingival display, presenting the most important factors
which may lead to having a Gummy Smile. e study
of Roe et al.,8 described that lip length and the upper
lip mobility rate are the main contributing factors. e
previous research of Peck et al.,9 stated that the exposure
of teeth and gingiva depends on the integrated eects
of a number of variables (increased muscle capacity,
vertical maxillary excess, greater interlabial gap at resting
position, and the amount of overjet and overbite). Pausch
et al.,4 mentioned that abnormal gingival and maxillary
anterior teeth display may take place due to numerous
anatomic or functional factors, either hereditary or
inborn. A narrow upper lip, an irregular eruption of teeth,
excessive protuberance or vertical maxillary growth, and
hypermobility of the maxillary lip and elevator muscle
are common reasons for a Gummy Smile.
In fact, several contributing factors are aecting
individuals to have a Gummy Smile. Sometimes one of
them is presented, although in some cases more than only
one cause can be seen. Correct diagnosis of the reason
leads to a proper treatment plan. e most common and
discussed factors associated with Gummy Smile are:
Altered passive eruption:
Also known as impaired passive eruption,1 is dened
as a condition in which the relationship between teeth,
alveolar bone in the maxilla, and the so tissues displays
an excessive gingiva. is, in turn, reveals the clinical
characteristic of Gummy Smile.10 In other words, altered
passive eruption (APE) is characterized by excessive
gingival exposure in relation to the crowns of the maxillary
teeth.11 In this case, the gingiva fails to migrate in the
apical direction during the eruption of teeth, thus,
it remains in a coronal position in relation with the
cementoenamel junction (CEJ), which results in having
an unacceptable gingival exposure and unfavorable small
size of the teeth when smiling.5 Miskinyar et al.,12 found
that the prevalence of this condition is about 12% of the
population. Altered passive eruption was rst identied
by the study of Coslet et al.,
13
and according to Rossi et al.,
10
it was classied into two types and two subtypes (Fig 1):
1. Type I : the vertical length of keratinized gingiva
is greater than normal, the mucogingival junction
(MGJ) is located in an apical position to the level of the
cementoenamel junction (CEJ), and clinical crowns
appear shorter.
2. Type II : the vertical dimension of the keratinized
gingiva is normal, although the mucogingival junction
is positioned at the level of the CEJ.
2.1 Subtype A : the measurement between the
maxillary alveolar crest and the CEJ is around 1.5 mm,
and in this case a regular attachment can be found.
2.2 Subtype B : the level of maxillary alveolar
crest is at the level of the CEJ, or occlusal to the CEJ in
some cases.
Bony maxillary excess:
This includes vertical maxillary excess and
bimaxillary protrusion.
Vertical maxillary excess:
Wolford et al.,15 defined Maxillary vertical
hyperplasia or vertical maxillary excess as an excessive
vertical growth of the maxilla which may or may not lead
to an anterior open bite. In his study Robbins16 explained
that to make the correct diagnosis, the face must be
divided into three equal thirds or parts for the critical
evaluation of the height of the face. Vertical maxillary
excess is noticed when the length of the lower third of
the face is more than the other two thirds, causing an
excessive gingival display.5
In the analysis of the face, vertical maxillary excess
has the following features: longer lower third of the face,
in relation with the upper and middle thirds, a greater
display of maxillary incisors at rest, an incompetent
lip, inclination towards class II malocclusion with or
without open bite, and a noticeable Gummy Smile. e
nose is longer as well, the alar bases are small and the
zygoma appears to be generally at. e lower third of
the face is long, leading to a retrognathic shape of the
jaw.17 Furthermore, the incisal edge of the upper anterior
teeth might be covered by the lower lip because of the
extravagant downward growth of the maxilla.16 Peck et
al.,9 and Mackley18 found that a Gummy Smile is highly
related to anterior vertical maxillary excess (about 2-3
mm). Moreover, Ezquerra and Berrazueta19 discuss
that excessive maxilla associated with the protrusion of
anterior alveolar bone consequently produce a Gummy
Fig 1. Classication of altered passive eruption (APE)14
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170
Smile. Whilst Wu et al.,6 in their study also stated that
anterior maxillary height (upper incisor to the palatal
plane) was considerably more in both male (+1.03 mm)
and female (+2.13 mm) groups who have Gummy Smile.
Bimaxillary protrusion:
Bimaxillary protrusion is a frequently diagnosed
deformity in African Americans20 and Asian populations as
well. is deformity is described regarding the protrusive
and buccally positioned maxillary and mandibular incisors,
as well as the enlarged prostration of the lips. It can be
found with an incompetent lip, excessive gingival display,
mentalis strain with an anterior open bite. Bimaxillary
protrusion refers to an abnormally protruded maxillary
and mandibular dentoalveolus. Generally, this presents
with malocclusion and dentoalveolar aring of both the
maxillary and mandibular anterior teeth, which cause
the lips to be protruded, thus, producing an additional
convexity of the facial prole. Bimaxillary protrusion is
mainly accompanied by several degrees of lip deciency
(dened as more than 4 mm of lip detachment at the rest
state). e tendency of the anteroposterior correlation is
to be a class II malocclusion with a decient mandible,
although it may also range from severe class II to class
III.21
The etiology behind bimaxillary protrusion is
associated with various reasons between genetics and
environment, such as mouth breathing, lip biting habit
and large size of the tongue.22
Keating et al.,23 discovered that in Caucasians with
bimaxillary protrusion, it is likely to notice a posterior
cranial base which is shorter than normal, a prognathic
maxilla with vertical excess, mild class II skeletal
occlusion, and a prostrate prole.
Conditions causing gingival enlargement
Gingival enlargement might be the outcome of
bacterial plaque-enhanced chronic inammation and
medications.5 Narwal et al.,24 showed in their case report
an abnormal unilateral palatalso tissue enlargementin a
61-year-old hypertensive female using amlodipine, which
is a safe antihypertensive drug. Ritchhart et al.,25 stated a
process behind uncontrolled cell proliferation in drug-
induced gingival overgrowth which is the suppression
of apoptotic pathways, with the following eect on the
normal gingival formation by cell turnover. Hormonal
dierences which take place in pregnancy and puberty,
in addition to the use of oral contraceptives have been
associated with gingival overgrowth.5 Other eects such
as age, demographic and pharmacokinetic changes,
genetic predisposition, oral hygiene condition, as well as
molecular and cellular variables may impact the mechanism
of gingival enlargement.25, 26 Orthodontic treatment
using orthodontic appliances can also participate in
the presence of gingival enlargement.27 In the case of
leukemia, leukemic cells might inltrate to the gingiva,28
and this will cause some manifestations to be present
such as gingival enlargement and bleeding.29
Short upper lip
e upper lip length is dened as the length from
the base of the nose (subnasale point) to the inferior
part of the upper lip (upper lip stomion point),8 which
is normally around 23 mm in males and 20 mm in
females.3 If an individual with excessive gingival display
has a short upper lip as well, the esthetic compromise
will be aected.16 e diagnosis of an excessive gingival
display can be done regarding the clinical measurement
of the upper lip length with an excessive amount of
tooth display at rest.5 Conversely, Roe et al.,8 found in
their study that in maximum smile, there is no notable
dierence in the gingival display between an individual
with a short or normal upper lip, and they concluded that
the association of some factors such as higher muscle
capacity, vertical maxillary excess, excessive interlabial
gap at rest, and the amount of overjet and overbite have
a greater eect on the gingival display than the upper
lip length itself. Moreover, Sarver et al.,30 explained that
what is crucial is the correspondence between the upper
lip length, the maxilliary incisors, and the commissure
of the mouth. In other words, the lip length should be
almost equal to the commissure of the mouth.
Hypermobility of the upper lip:
In the case of normal face height, gingival levels,
lip length and length of central incisors in a patient who
has an excessive gingival display, the possible etiology
is hypermobility of the maxillary upper lip.16 Upper lip
mobility was explained as the volume of lip movement that
exists when an individual smiles. is was measured by
deducting the incisal shown at rest from the dentogingival
display during a full smile. Hypermobility of the upper
lip is associated with a hyper function of the lip elevator
muscles and basically leads to excessive gingival display.19
Peck and Peck31 reported an average lip movement
of 5.2 mm (23% decrease) from a measured lip length
of 22.3 mm during a full smile. Furthermore, in a study
evaluating spontaneous smiles, Tarantili et al.,32 identied
a 28% decrease in the initial upper lip length, while
Roe et al.,8 concluded the overall means of lip mobility
for females with normal lip length, females with short
lip length, males with normal lip length and males with
Mahardawi et al.
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short lip length were 5.8 ± 1.7 mm, 5.0 ± 1.3 mm, 6.7 ±
1.5 mm, and 5.7 ± 1.1 mm, respectively. Moreover, Sabri
et al.,3 stated that in smiling, the upper lip is elevated by
about 80% of its original length. Bhola et al.5, as well as
Robbins16 stated that the upper lip is generally elevated
around 6-8 mm from the rest position to the position
reached when a full smile takes place.
Treatment of gummy smile:
Excessive gingival display can be managed by a
variety of procedures. ese procedures include non-
surgical and surgical methods. e underlying cause of
excessive gingival display or Gummy Smile has the main
eect on the type of procedure that will be performed.33
Non-surgical procedures may include Botulinum toxin
type A injection as well as orthodontics, While surgical
procedures might include lip repositioning or orthognathic
surgery following orthodontics.
Robbins16 dened the healthy gingiva as having
a minimal length of approximately 3 mm from the
gingival crest to the alveolar crest. In the case of altered
passive eruption, a higher amount will exist, and the
treatment of choice is normally gingivectomy following
by aesthetic crown lengthening to attain the desired
dimension and morphology of teeth. However, when the
diagnosis shows bone levels close to the CEJ, a gingival
ap with ostectomy is performed, or what is also known
as an apically positioned ap.34 Orthodontic eruption
or intrusion can also be done when having gingival
asymmetry on one or multiple anterior teeth34
In the case of vertical maxillary excess, the only
treatment option to consider is orthognathic surgery.11 is
is applied to impact the maxilla considering the amount of
gingival exposure diagnosed. Maxillary impaction allows
correction of the Gummy Smile, long face syndrome,
specic types of open bite from a skeletal origin and labial
sealing.35 e Le Fort I osteotomy of the maxilla allows
reduction of bone between the nasal oor and apices of
maxillary teeth which permits superior repositioning
(impaction) of the maxilla.17
When having bimaxillary protrusion, the treatment
option may be composed of rst premolar extractions
followed by the osteotomy through the extraction sites
to mobilize the anterior segment of the maxilla. e aim
is to setback the segment in addition to lesseningthe
labial aring of the incisors. Maxillary setback alone
can sometimes provide a substitute for the treatment of
anterioposterior maxillary excess without any need for
tooth extraction or segmental osteotomy in these cases:
(1) it is contraindicated to perform extractions in
an orthodontic diagnosis (no dental crowning, adequate
curve of Spee, etc.),
(2)the proclination of maxillary incisors can be
adjusted to an acceptable position with a Le Fort I osteotomy
in addition to clockwise rotation.21
In the presence of external factors causing gingival
overgrowth, the treatment plan should be focused on the
exact cause of the enlarged gingiva. Meticulous history
taking, in addition to an excisional/incisional biopsy and/
or hematologic/histologic inspection might be performed
generally to make the correct diagnosis of the uncommon
conditions of gingival enlargement. Plaque control is an
important aspect of treatment in all the patients. Some
of these cases may resolve when the external element
that is inducing the gingival enlargement is adjusted or
suspended, For example, gingival overgrowth during
pregnancy and puberty might need the elimination of
all local irritants followed by surgical treatment for the
removal of any brotic residuals.36
For the excessive gingival display resulted from
short upper lip and/or hypermobility of the upper
lip, a surgical procedure known as lip repositioning
surgery is preferred for a minimally invasive surgery.
It is composed of an oval mucosal excision followed
by coronally advanced ap. is procedure is done to
reduce the hyperactivity of the elevator muscles and
reform the depth of the vestibule.37 It was rst described
by Rubinstein and Kostianovsky38 and the aim was the
treatment of excessive gingival display associated with
hypermobility of the lip, and was then modied by Litton
and Fournier39 to include also the treatment of Gummy
Smile caused by short upper lip, by separating the muscles
from the underlying bony structures to place the upper
lip in a coronal position. is surgical procedure was
accompanied with no complications, although there were
some incidences of relapse,40 consequently, some attempts
were done to improve it by Miskinyar.12 Recently, Bhola
et al.,5 described a technique similar to the one which was
described by the article of Rubinstein and Kostianovsky
under the name of Lip Stabilization Technique (LipStaT).
e only obvious dierence between the two techniques
is that in LipStaT, a vertical incision is done posteriorly
to connect the inferior incision (at the mucogingival
junction) and the superior incision (into the vestibule).
e ratio of this incision is the height being double of
gingival exposure during a full smile. While in Rubinstein
and Kostianovsky technique, the two incisions were
approximated till they meet posteriorly.
Currently, another nonsurgical treatment option is
the injection of Botulinum toxin type A which has been
suggested for treatment of hypermobility of the upper
lip, but this may only provide temporary advantages.41
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172
Polo41 reported a relapse of around 2 mm aer 24
weeks of following up. is was similar for Indra et al.,42 by
reporting a relapse of treatment in the third month. Yet it is
still a viable option for those who do not prefer undergoing
surgeries, and need only a minimal treatment procedure.
DISCUSSION
It was stated recently that the dimension and visibility
of teeth, and upper lip position were crucial eects when
judging smile attractiveness.43 Many studies described the
acceptable gingival exposure and the concept of Gummy
Smile (table below). Having an acceptable smile in the
eyes of other people is, in fact, a subjective view, because
the perception of a nice smile has diered from country
to country, from study to study, and even when males
or females are evaluating the smile. In other words, a
study showed that the male raters diered in respect of
gender specicity when judging the attractiveness of
the smile, while female raters rated males less gender
specic.4 erefore, no reliable or unied measurements
were stated in the literature regarding a clear description
of having an attractive smile or when it is diagnosed as
a Gummy Smile. Although the dierent visions of an
accepted gingival exposure were evaluated in dierent
countries, they should be identical for the same ethnic
origins. Sabri et al3 concluded that an ideal smile has
the features of an upper lip that will reach the gingival
edges when smiling, in addition to an upward or straight
curvature through the philtrum and commissures; with
maxillary incisal margins parallel to the lower lip line;
with no lateral negative space or minimal if it presents;
and a commissural line, as well as an occlusal frontal
plane parallel to the line drawn through the pupils of the
eyes; and attractive integration of gingiva and teeth. e
acceptable amount of gingival exposure when smiling
was mentioned in several studies. For instance, Kokich
et al.,44 reported noticeably unattractive lip to gingiva
distance when the exposure is 4 mm by laypersons and
when it is 2 mm by orthodontists, while Geron and Atalia45
accepted only 1 mm of gingival display when smiling.
Pausch et al.,4 concluded in their study that a 0- to 2-mm
exposure of the maxillary gingiva was acceptable when
an individual smiles. In addition to that, they found that
although the Gummy Smile is unattractive, it is much
better than invisible or minimally visible maxillary teeth
when smiling. Bhola et al.,5 explained that aected by
the increased aesthetic concerns, a gingival exposure of
more than 1 mm during smiling might be diagnosed as
excessive gingival display (EGD). Van der Geld et al.43
concluded in their study that a lip line height that exposed
more than 4 mm of gingival display was considered as
a Gummy Smile line. Jannani et al.46 stated that a smile
is introduced as attractive when the maxillary teeth are
entirely shown in addition to approximately 1 mm of
gingival display. However, a gingival display not more
than 2-3 mm is also contemplated as acceptable, while
a disproportionate exposure (>3 mm) is basically stated
as not pleasant. Pinto et al.,11 mentioned three kinds of
a smile: high, medium and low, and the high smile is
considered acceptable when accompanied with exposed
gingiva of 1 to 3 mm.
Moreover, treatment of Gummy Smile was being
practiced many years ago. Several techniques and procedures
were developed to reduce the excessive gingival display
and change it into an aesthetic, acceptable appearance.
Taking the bony maxillary excess into consideration,
a review of the literature may conclude that although
the treatment of Gummy Smile caused by vertical
maxillary excess and/or bimaxillary protrusion is not a
new procedure, no studies have made a clear treatment
plan, and no one has described a step by step way to
predict the treatment according to a certain prediction
plan before performing orthognathic surgery, based
on clear measurements of moving the maxilla. us, a
thorough prediction and movement plan of the maxilla
for Gummy Smile treatment might be of a great value to
help surgeons establish an accurate treatment plan based
on scientic data, not only experience. e acceptable
gingival exposure and the diagnosis of Gummy Smile
in some previous studies is shown in Table 1.4,5,11,43-46
CONCLUSION
Gummy Smile is a condition in which an increasing
awareness has been noticed recently. erefore, it is
attracting more attention from all the clinicians to nd
the best solutions with the least complications and
relapse, as well as the most satisfying results for every
patient. Additional unied standards of accepting and
not accepting the amount of gingival exposure might
be better to help with diagnosing and deciding whether
to perform surgery or consider the gingival exposure as
acceptable. is should be decided considering the ethnic
origin and trying to collect a wider range of opinions, not
only taking experts’ view because they will judge more
critically. is could be done by performing a greater
statistical analysis regarding this topic, including more
people to evaluate and judge.
In addition, clear prediction planning of moving
the maxilla to improve the condition of Gummy Smile,
taking into account if it is resulted from vertical maxillary
excess alone or with bimaxillary protrusion, would be of
a great benet to perform a well-planned surgery. is
Mahardawi et al.
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Review Article SMJ
TABLE 1. Acceptable gingival exposure and the diagnosing of Gummy Smile in some studies in the literature.
Authors Year Acceptable gingival exposure Having a Gummy Smile
Kokich et al44 1999 Less than 4 mm by laypersons 4 mm or more by laypersons 2 mm or
Less than 2 mm by orthodontists more by orthodontists
Geron and Atalia45 2005 Untill 1 mm More than 1 mm
Van der Geld et al.43 2011 Untill 4 mm More than 4 mm
Jannani et al.46 2014 2-3 mm More than 3 mm
Pinto et al.11 2015 1-3 mm More than 3 mm
Bhola et al.5 2015 Untill 1 mm More than 1 mm
Pausch et al.4 2017 0-2 mm More than 2 mm
surgery should be done according to certain principles and
criteria, not depending upon each surgeon’s experience
or preference. To reach this stratied surgical plan, this
literature review suggests further studies to design a
prediction formula of moving the maxilla, following
certain calculations regarding the amount of vertical
maxillary excess, bimaxillary protrusion, x-rays, and
considering opinions of experienced surgeons to get
the best aesthetic results.
ACKNOWLEDGMENTS
e authors would like to acknowledge the sta,
dental assistants, and our colleagues in the Department
of Oral and Maxillofacial Surgery, Faculty of Dentistry,
Mahidol University.
Funding: e authors received no funding
Conict of interest: e authors declared that they have
no conicts of interest.
Ethics approval: Not required
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