Asymmetrical Smiles Corrected by Botulinum Toxin Serotype A

ANTHONY V. BENEDETTO, DO, FACP�

OBJECTIVE The objective was to identify the cause of an asymmetrical smile and to ascertain whether ornot it would be correctable by injections of Botulinum toxin A (BTX-A).

METHODS Five patients with asymmetrical smiles were identified and found to lower one side of theirlower lip in an exaggerated fashion when smiling or laughing. After close observation, it was determinedthat the ipsilateral depressor labii inferioris of the lower lip was hyperkinetic and retracted that side of thelips lower than its contralateral side when smiling or laughing. Injections of low-volume and low-dose BTX-A (BOTOX, Allergan, Inc.) were placed into the depressor labii inferioris on the side where the lower lipretracted the lowest.

RESULTS All of the five patients with asymmetrical smiles presented with unilateral hyperkinetic de-pressor labii inferioris and responded to injections of BOTOX. Their lower lips became level and theirsmiles were symmetrical within 1 week of the BOTOX treatments. Their lip symmetry lasted for at least 6months after their initial treatment. With each additional treatment, the duration of BOTOX lasted evenlonger, averaging approximately 7 months.

CONCLUSION BOTOX is an effective, safe, and long-lasting treatment for lower lip asymmetries causedby a hyperkinetic depressor labii inferioris.

Dr. Benedetto is a stock holder, is on the Speakers Bureau for Allergan, and has been a member of the BOTOXNational Education Faculty Network since 2002.

Facial asymmetry (FA) can result from many dif-

ferent causes, which will determine whether or

not it can be reversible. There are three basic types of

facial asymmetries. Acquired FA is the result of a

medical or physical episode, e.g., a cerebral vascular

accident or facial nerve (Bell’s) palsy. FA can be the

result of iatrogenic causes as in the case of facial nerve

palsy resulting from the severance of the facial nerve

during a parotidectomy or other types of surgery on

the face (e.g., deep surgical resection of skin cancer).

A temporary paresis can be iatrogenically produced

by the inadvertent diffusion to adjacent muscles of

botulinum toxin (BTX) injected for therapeutic or

cosmetic reasons. In the case of a parotidectomy, or

deep tissue surgical resections and severance of the

facial nerve, the palsy is usually irreversible depending

on the location of the nerve trunk interruption. In the

case of the inadvertent paresis resulting from a

treatment of BTX, however, the palsy is temporary

and reversible. A third type of FA can be idiosyncratic

or familial, whereby one of a pair of muscles on one

side of the face can be comparatively stronger or

weaker than its partner muscle on the contralateral

side of the face.1 This is seen as a subtle displacement

in the level of the eyebrows or, more obviously, as an

asymmetrical smile.2 In many, a naturally occurring

asymmetrical smile usually is a familial trait passed

down from one generation to the next, typifying a

certain characteristic trait such as the ‘‘family smile’’

(Figure 1). In this pilot study, patients with idiosyn-

cratic asymmetrical smiles were treated with injec-

tions of botulinum toxin serotype A (BTX-A),

specifically BOTOX (Allergan, Inc., Irvine, CA),

which produced a symmetrical, more balanced smile.

& 2007 by the American Society for Dermatologic Surgery, Inc. � Published by Blackwell Publishing �ISSN: 1076-0512 � Dermatol Surg 2007;33:S32–S36 � DOI: 10.1111/j.1524-4725.2006.32329.x

3 2

�Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine, and MedicalDirector, Dermatologic SurgiCenter, Philadelphia, Pennsylvania

Case 1

A 46-year-old professional woman was always

bothered by her obviously ‘‘crooked’’ or asymmet-

rical smile, which was present for as long as the

patient can remember and as early as preadoles-

cence. Because of her status in the work place,

smiling or laughing was an anxiety provoking emo-

tive response. This caused the patient to always

cover her mouth when the occasion for laughing or

smiling presented itself. The asymmetrical smile was

determined to be caused by a unilateral hyperkinetic

depressor labii inferioris (DLI) on the left when

compared to the strength and activity of its paired

DLI on the contralateral right side (Figure 2). After

identifying the reason for the patient’s asymmetrical

smile, 3 U of BOTOX were injected into the belly of

the hyperkinetic DLI on the left side of the lower lip.

Within 96 hours the stronger left DLI was weakened

and resulted in a leveling of the lower lip margin

causing the lower lip to appear normal and sym-

metrical when the patient smiled or laughed. The

symmetrical smile lasted approximately 5 1/2

months after the first treatment and 6 to 8 months

after subsequent treatments (see Table 1).

Figure 1. Father (A) and daughter (B) have the same asymmetrical smile that manifests as an uneven lower lip margin on theright.

Figure 2. Asymmetrical smile with depressed lower lip margin on the left before (A), 3 weeks after (B), and 6 months after(C) 3 U of BOTOX. Note the reduction of the lower ‘‘dental show.’’

3 3 : S 1 : J A N U A RY 2 0 0 7 S 3 3

B E N E D E T T O

Case 2

A 49-year-old woman was unaware of her asym-

metrical smile that was characterized by an uncon-

scious excessive lowering of the right side of the

lower lip when she smiled or laughed. This was

brought to her attention during a treatment session

of BOTOX injections for her upper face wrinkles

(Figure 3). After determining the right DLI was

hyperkinetic compared to its contralateral paired

muscle, 2 U of BOTOX were injected into the belly

of her right DLI. In approximately 1 week, the pa-

tient’s smile was noticeably even and symmetrical.

The effects of the BOTOX lasted approximately 5

months after the first treatment and 7 to 8 months

after subsequent treatments (see Table 1).

Case 3

A 21-year-old female presented with a right sided

lower lip hyperkinetic DLI causing an asymmetrical

smile that was present since birth. This patient’s

smile closely resembled that of her father’s smile,

which was identical in location and appearance

(Figures 1 and 4). None of her other three siblings

(two older brothers and one younger sister) or her

mother exhibited such an asymmetrical smile. After

identifying the right DLI as hyperkinetic and the

cause of her asymmetrical smile, 1 U of BOTOX was

then injected intramuscularly into it. This produced

a symmetrical smile that lasted more than 8 months

with the first treatment (see Table 1).

Methods

BOTOX was the only BTX-A used to treat the

hyperkinetic DLI of the patients presented. A vial of

100 U of BOTOX was reconstituted with 1 mL of

preserved normal saline. After the causal hyperkin-

etic DLI was identified and confirmed, 1 to 3 U of

BOTOX were injected into the belly of the muscle

just below the mental crease to avoid injecting the

lower fibers of the orbicularis oris and at a point that

was medial to the depressor anguli oris and lateral to

the mentalis. Individual dosing was selected accord-

ing to the severity of the asymmetry and the per-

ceived strength of the hyperkinetic DLI.

TABLE 1. Details of Cases

Case Sex Age of onset Age (years) Location BOTOX units Duration (months)

I Female Childhood 46 Left DLI 3 U 6

II Female Unknown 49 Right DLI 2 U 7

III Female Birth 21 Right DLI 1 U 8

IV Male Childhood 55 Right DLI 3 U 6.5

V Female Childhood 32 Right DLI 2 U 7.5

Figure 3. Patient with lower right asymmetry before (A) and 3 weeks after (B) 2 U of BOTOX. Note the elimination of thelower ‘‘dental show.’’

D E R M AT O L O G I C S U R G E RYS 3 4

B O T O X C O R R E C T I O N O F A S Y M M E T R I C A L S M I L E S

Results

In less than 5 days a typical low dose of 1 to 3 U of

BOTOX weakened the hyperkinetic side of the lower

lip and made the smiles of the patients symmetrical.

The effects of the injected BOTOX lasted at least 4

to 5 months after the first treatment and much

longer with subsequent treatments, producing a

symmetrical smile that lasted a mean of 7 months for

each patient (see Table 1).

Discussion

FAs when acquired as a result of nerve injury can be

reversible or permanent. Facial nerve (Bell’s) palsy

caused by an inflammatory process usually is re-

versible, but it also can be recurrent. When FA is the

result of damage to the facial nerve because of an

accidental episode or an incidental surgical resection,

the FA usually is permanent but eventually can be

reversible. This depends on how completely severed

the facial nerve is, how distal the injury is from the

main trunk of the facial nerve, and how well the

damaged nerve can repair and reanimate itself. Iat-

rogenically acquired FAs that result from a segmen-

tal facial palsy produced by the unintentional but

inadvertent diffusion of BTX into nontargeted ad-

jacent muscle fibers after a therapeutic or cosmetic

treatment are temporary and reversible. Finally,

there is another type of FA that is idiosyncratic to a

particular person and can manifest either randomly

in isolated individuals or in persons in different

generations of a particular family.2

These familial traits frequently can be disconcerting

and embarrassing to [by] the bearer. Before BTX such

FAs were correctable only by surgical intervention.

Now BTX can provide a simple, noninvasive, safe

way of correcting obtrusively distracting asymmet-

rical smiles.3 Four of our patients were aware of their

lip asymmetry; one was not. When the asymmetrical

smile was identified and brought to the attention of

the one patient who was unaware of it, that patient

became a faithful and regular recipient of the cor-

rective BOTOX treatments, especially when she

realized how easily and painlessly it was to treat. It is

essential that a physician possess a comprehensive

understanding of the functional anatomy of the mi-

metic muscles of the face when treating patients with

BTX.4,5 When evaluating the patients in this pilot

study, it became apparent that the asymmetries of

their lower lips were created by the enhanced down-

ward pull of one of the paired DLIs.6 The idiosyn-

cratic, unilateral, hyperkinetic DLI of the lower lip

caused an ipsilateral retraction of the lip margin

lower than its contralateral side, which resulted in lip

asymmetry during a smile or while laughing. A few

units of highly concentrated BOTOX injected into the

overactive muscle fibers of the DLI responsible for the

asymmetry of the lower lip produced a gentle relax-

ation of the ipsilateral DLI which then functioned in

unison with its contralateral DLI partner resulting in

symmetry to the patients’ smile. Such corrections are

easily accomplished when one can identify the source

of the asymmetry. Accurate injections of precise

amounts of low-volume BOTOX can then be utilized

Figure 4. Patient with a characteristic ‘‘family smile’’ before (A) and 7 months after (B) her first treatment with 1 U of BOTOX.Note the elimination of the lower ‘‘dental show.’’

3 3 : S 1 : J A N U A RY 2 0 0 7 S 3 5

B E N E D E T T O

to produce a very long-lasting, well-appreciated cor-

rection of naturally occurring, but unwanted, lower

lip asymmetry.

When the hyperkinetic DLI is weakened, the result-

ant leveling of the lower lip in an asymmetrical smile

may diminish and even eliminate the lower ‘‘dental

show’’ that the patient has become accustomed to

seeing during a smile or laughter. This dental show

commonly is present only on the side of the hyper-

kinetic DLI and only because that DLI is hyperactive.

When the smile becomes symmetrical the dental

show commonly is eliminated. Likewise, when the

asymmetry occurs in the upper lip there frequently is

a ‘‘gingival show’’ instead. The releveling of an upper

lip asymmetry, however, is not as straightforward as

it is in the lower lip, because of the different levators

that might be producing the asymmetry.

Before any correction of lower lip asymmetry, the

patient must be advised of the possible reduction in

lower lip dental show. Also there are times when the

first treatment with BOTOX does not exactly pro-

duce the expected outcome, i.e., a perfectly sym-

metrical smile. Rather, what usually is produced is a

‘‘more symmetrical’’ smile. Informing the patient of

this beforehand will avoid disappointment afterward.

It is also possible that just 1 or 2 U of BOTOX in a

particular patient will overly weaken the ipsilateral

hyperkinetic DLI, especially in subsequent treatments

during maintenance, whereby the contralateral DLI

may or may not overly compensate and create a sec-

ondary asymmetrical smile. In such situations 0.5 to

1 U of BOTOX in the contralateral DLI may be

needed to maintain dynamic symmetry. Therefore,

perfect results should never be guaranteed particu-

larly when treating for the first time any new ana-

tomic site with BOTOX, especially in the lower face.

In this pilot study, none of the patients experienced

any complications. What probably can occur as a

complication is the overtreatment of a DLI by an

overzealous injector.7 Minimal doses in minimal vol-

umes of BOTOX should be injected because it is also

possible that an exaggerated response of the treated

DLI to 1, 2, or more units of BOTOX might occur,

particularly with subsequent maintenance treatments.

This would result in an inability of the patient to

retract the lower lip. An adynamic DLI would inter-

fere with the daily activities of eating, drinking, and

speaking. Biting of the lower lip while eating or

speaking conceivably could occur. Incontinence of li-

quid and solid food could also result. Large volumes

of injected BOTOX could diffuse peripherally and

inadvertently affect the mentalis, the contralateral

DLI, or even the ipsilateral depressors anguli oris and

orbicularis oris depending on the volume injected.

None of these complications, however, were ever ex-

perienced by any of the patients in this study.

Because the use of BOTOX in clinical medicine has

become more readily acceptable by physicians and

patients, simple and safe treatments such as the

noninvasive correction of an asymmetrical smile can

become an indispensable component of a dermatol-

ogist’s therapeutic armamentarium.

References

1. Benedetto A. Cosmetic uses of botulinum toxin a in the upper face.

In: Benedetto AV, editor. Botulinum toxin in clinical dermatology.

London: Taylor & Francis Group, 2005:p. 78–95.

2. Benedetto A. Cosmetic uses of botulinum toxin in the mid face. In:

Benedetto AV, editor. Botulinum toxin in clinical dermatology.

London: Taylor & Francis Group, 2005:p. 156–61.

3. Blitzer A, Binder WJ, Aviv JE, et al. The management of hyper-

functional facial lines with botulinum toxin. Arch Otolaryngol

Head Neck Surgery 1997;123:389–92.

4. Carruthers J, Carruthers A. Botox use in mid and lower face and

neck. Semin Cutan Med Surg 2001;20:8592.

5. Fagien S. Botulinum toxin type A for facial aesthetic enhancement:

role in facial shaping. Plast Reconstr Surg 2003;112:65–185.

6. Hoefflin SM. Anatomy of the platysma and lip depressor muscles: a

simplified mnemonic approach. Dermatol Surg 1998;24:1223–31.

7. Klein AW. Complications and adverse reactions with the use of

botulinum toxin. Semin Cutan Med Surg 2001;20:109–20.

Address correspondence and reprint requests to: Addresscorrespondence and reprint requests to: Anthony V.Benedetto, DO, FACP, Dermatologic SurgiCenter, 1200Locust Street, Philadelphia, PA, or e-mail:Avb@benedettoderm.com.

D E R M AT O L O G I C S U R G E RYS 3 6

B O T O X C O R R E C T I O N O F A S Y M M E T R I C A L S M I L E S