botox excessive gingival display

SHORT COMMUNICATION

Botulinum toxin type A in the treatment ofexcessive gingival displayMario PoloSan Juan, Puerto Rico

Purpose: One cause of excessive gingival display is the muscular capacity to raise the upper lip higher thanaverage. Several surgical procedures have been reported to improve the condition, but surgery alwaysinvolves risk and is costly. Botulinum toxin type A (BTX-A) (Botox; Allergan, Irvine, Calif) has been studiedsince the late 1970s for the treatment of several conditions associated with excessive muscle contraction orpain. This clinical pilot study was performed to determine whether BTX-A injections would reduce excessivegingival display. Material: Five subjects with excessive gingival display due to hyperfunctional upper lipelevator muscles were treated with BTX-A injections. Results: This treatment modality was effective,producing esthetically acceptable smiles in these patients. The improvements lasted 3 to 6 months.Conclusions: Injection with BTX-A at preselected sites is a novel, cosmetically effective, minimally invasivealternative for the temporary improvement of gummy smiles caused by hyperfunctional upper lip elevator
muscles. (Am J Orthod Dentofacial Orthop 2005;127:214-8)
The display of excessive gingival tissue in themaxilla upon smiling has been called a “gummysmile,” a condition some consider esthetically

displeasing. Some people with excessive gingival dis-play are self-conscious or embarrassed about it, andsome are psychologically affected.1 Although the inci-dence of excessive gingival display has not beenestablished, it is fairly common. Etiologic factors canbe skeletal, gingival, muscular, iatrogenic, or somecombination of these. The literature contains manyreports that address the skeletal problem of verticalmaxillary excess2-6 and gingival problems related todelayed passive eruption.7-9 In his review of structuralesthetic rules, Rufenacht10 referred to this condition.Robbins11 reported differential diagnosis and treatmentof excessive gingival display.

The muscular capacity to raise the upper lip higherthan average (hyperfunctional muscle) can cause exces-sive gingival display.12 Upper lip elevator musclesinclude the levator labii superioris, levator labii supe-rioris alaeque nasi, levator anguli oris, zygomaticusmajor, zygomaticus minor, and the depressor septi nasi.Several surgical procedures have been reported in theliterature to correct a gummy smile caused by hyper-functional upper lip elevator muscles (mostly thelevator labii superioris muscles). Rubinstein and

Medical faculty orthodontist, Department of Surgery, San Jorge Children’sHospital/Plastic and Reconstructive Center, San Juan, Puerto Rico.Reprint requests to: Dr Mario Polo, 702 La Torre de Plaza, 525 F.D. RooseveltAve, San Juan, Puerto Rico 00918-0702; e-mail, [email protected], May 2004; revised and accepted, September 2004.0889-5406/$30.00Copyright © 2005 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2004.09.013
214

Kostianovsky13 described a procedure whereby anelliptical portion of gingiva and buccal mucosa wasexcised and the borders approximated and suturedtogether. Litton and Fournier14 referred to “muscledetachment from the bony structures above” to bringthe lip down. Miskinyar15 used a different surgicaltechnique to treat 27 patients, including 7 who hadrelapsed after being treated with the Rubinstein andKostianovsky technique. Miskinyar claimed only “aminor success rate, and even complete disappointmentwith previous techniques.” In his new technique, heperformed myectomy and partial resection of the leva-tor labii superioris muscles; 1 or both of the bellies ofthe muscles were amputated 1.0 to 2.0 cm at theirjunction with the orbicularis oris muscle. No referencewas made to a skeletal etiology for the problems, asstated by Sullivan,16 and no follow-up time was dis-cussed. Ellenbogen17 reported that resection of thelevator labii superioris is short-lived, with the gummysmile returning within 6 months. He advocated placinga spacer, either nasal cartilage or prosthetic material,between the stumps to prevent the muscles from beingreunited and again hyperelevating the lip. Miskinyar18

stated that patients he followed for as long as 8 yearsshowed no recurrence or disappointing results,15 but healso pointed out possible disadvantages with the spacertechnique: migration of the spacer to an undesired siteand the muscle ends reuniting, rejection of a foreignbody (in the case of prosthetic spacers), and the needfor a second surgical procedure if nasal cartilage isused. Rees and LaTrenta19 described a camouflage
procedure through the columella, whereby a subperios-

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Polo 215

teal dissection of the upper lip elevators was performed.Ezquerra et al20 presented a multidisciplinary approachfor treating a high smile line with excessive gingivaldisplay: either LeFort I osteotomy or gingival andalveolar bone remodeling surgery, or a modified (in-traoral) camouflage procedure as described by Rees andLaTrenta,19 or a combination of the latter 2.

A nonsurgical alternative for reducing excessivegingival display caused by muscle hyperfunction wouldbe advantageous. Botulinum toxin has been underclinical investigation since the late 1970s for thetreatment of several conditions associated with exces-sive muscle contraction or pain.22 Botulinum toxin isproduced by the anaerobic bacterium Clostridiumbotulinum. There are 8 different serotypes of botulinumtoxin. Type A (BTX-A) is the most potent and the mostcommonly used clinically. Botox (Allergan, Irvine,Calif) is a purified BTX-A isolated from the fermenta-tion of C botulinum. It is a stable, sterile, vacuum-driedpowder that is diluted with saline solution withoutpreservatives. BTX-A weakens skeletal muscles bycleaving the synaptosome-associated protein SNAP-25,thus blocking the release of acetylcholine from themotoneuron and enabling the repolarization of thepostsynaptic terminal. As a result, the muscular con-traction is blocked. The production of acetylcholine isnot affected by this blockade of the neuromusculartransmission. The effects last 3 to 6 months, althoughsome investigators have reported a longer duration inpatients exposed over a prolonged period of time.21

BTX-A has been used to treat strabismus,23 cervicaldystonia,24 blepharospasm and hemifacial spasm,25 hy-perfunctional larynx,26 juvenile cerebral palsy,27 spas-ticity,28 pain and headache,29 occupational dystoniaand writer’s cramp,30 temporomandibular disorders,31

myofacial pain,32 and oromandibular dystonia andbruxism,33 and several other conditions. Since 1987,BTX-A has been widely used for the cosmetic treat-ment of hyperfunctional facial lines.34

The purposes of this pilot study were to determinewhether BTX-A could also be used in patients withhyperfunctional upper lip elevator musculature to cor-rect a gummy smile and to establish the optimalminimal dose of BTX-A needed to obtain cosmeticallypleasing results.

MATERIAL AND METHODS

Twelve women with excessive gingival displaywere screened, and 5 were selected for this study. Theyranged in age from 16 to 23 years. Cephalometricanalysis was performed to determine whether thegummy smile was skeletal (ie, vertical maxillary ex-
cess). Periodontal evaluation was performed to rule out
delayed passive eruption leading to excessive gingivaldisplay. These patients had a history of fairly good oralhygiene, although mild gingivitis was acceptable. Somewere receiving active orthodontic treatment. Informa-tion about the procedure, its possible benefits, risks, andside effects, and the expected duration of the results, ifany, was given in detail to the patients and the parentsof the minors verbally and in writing. All agreed toparticipate. Written informed consent was obtained.

The study was divided into 3 phases. At the beginningof phase I, extraoral photographs were taken, including aclose-up photograph with a ruler placed vertically at thefacial midline while the patient was smiling (Fig 1). Thespot where the superior portion of the ruler barely touchedthe midline of the columella’s most inferior portion at thenasolabial junction was designated reference point 1(RP1). The ruler passed through the middle of the phil-trum and extended inferiorly into the midline of the chin.The incisal edge of the maxillary right central incisoralong its mesial surface at the midline was designatedreference point 2 (RP2). The distance between the refer-ence points was constant for each subject when thefull-smile photographs were taken; minor variations (1.0mm or less) between RP1 and RP2 measurements takenbefore and after the procedure were compensated forwhen they were recorded.

Injections were made intramuscularly under elec-tromyographic guidance.35 BTX-A was diluted by add-ing 4.0 mL of 0.9% normal saline solution withoutpreservatives to 100 U of vacuum-dried C botulinumtype A neurotoxin complex, according to the manufac-turer’s dilution technique. This resulted in a 2.5 U/0.1mL dose. After carefully reviewing the literature forsmall muscle dosage, a dose of 1.25 U per muscle siteper side was selected as a baseline to start the study.Under sterile conditions, 1.25 U per side was injected inboth the right and left levator labii superioris andlevator labii superioris alaeque nasi muscles (LLS), andan additional 1.25 U per side at the overlap areas of thelevator labii superioris and zygomaticus minor muscles(LLS/ZM). Aspiration before BTX-A injection wasdone to avoid involuntary deposition of the toxin intothe facial arteries. During this phase, patient 1 receivedan additional 1.25 U per side at the origin of thedepressor septi nasi muscle at the orbicularis orismuscle (OO), 2 to 3 mm inferior to the nostrils and 2 to3 mm from the midline.

The patients were clinically evaluated 1 week, 2weeks, 4 weeks, and 16 weeks postoperatively. Duringthe first evaluation, they were asked to report anyadverse reactions or side effects associated with theprocedure. They also reported how long after the
procedure they started noticing the effects on their

-up s

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216 Polo

upper lips and smiles. During the 2-week evaluation, inaddition to reviewing again for adverse reactions andonset of changes, subjects were evaluated to determinewhether the results obtained were sufficient or whetheradditional muscular weakness by reinjection was desir-able.

Phase II of the study began 1 month later. Afterdetermining 2 weeks postoperatively that additional injec-tions could enhance the results, it was decided to inject theLLS and the LLS/ZM with a supplemental dose ofBTX-A. All patients agreed to undergo this second ses-sion. The subjects received 0.625 U per side at theLLS/ZM sites and either 1.25 U or 0.625 U at the LLSsites. The latter was determined by clinical evaluation ofeach patient’s results observed from phase I. The patientswere clinically evaluated 2 weeks, 4 weeks, and 16 weekspostoperatively after the phase II injection. Facial photo-graphs were obtained at the 2-week postoperative visit.During the 16-week follow-up visit, the patients wereevaluated for evidence of lasting or remaining effects.

Phase III of the study followed a similar protocol,except that all patients received 2.5 U injections perside at the LLS and LLS/ZM sites. Patients 1 and 4 alsoreceived 1.25 U per side at the OO site described above.They had the greatest amount of upper lip elevationnear the philtrum. They were then evaluated 2 weeks, 4weeks, and 16 weeks postoperatively. Photographswere obtained at the 2-week postoperative visit.

One patient requested an additional treatment. Shereceived 1.5 U per side at LLS and LLS/ZM sites and1.25 U per side at OO sites 3 months after the phase IIIinjection. She received these lower doses because shewas experiencing residual effects from her last BTX-Aadministration, but she nevertheless wanted to enhancethe results previously achieved.

RESULTS

The results of this pilot study were analyzed both

Fig 1. Drawing with landmarks and close

subjectively, by clinical evaluation of the gummy

smile, and objectively, with pre- and postoperativephotographs (Fig 2).

The following measurements (called A, B, and C)were recorded: A: RP1 to superior border of upper lipvermilion; B: RP1 to inferior border of upper lipvermilion; and C: inferior border of upper lip vermilionborder to junction of the gingiva with the maxillaryright central incisor crown along its own midline.

All 5 patients began to show improvement approx-imately 10 days after the injections. After 14 days,results were definitely observed. The pre- and postop-erative measurements were recorded and compared. At2 weeks after injection in phases II and III, all 5 patientshad a mean increase of measurements A and B of 4.20mm and a mean decrease of measurement C of 4.20mm (Table I).

The effective increase in upper lip length uponsmiling was 131%, 120%, 124%, 117%, and 129%(mean, 124.2%) for patients 1 through 5, respectively.Gingival exposure went from 4.0 mm to 0 mm forpatients 1 and 3, from 4.0 mm to 1 mm for patient 4,and from 5.0 mm to 0.0 mm for patients 2 and 5. Therewas no significant difference in the measurementsbetween phase II and phase III. Patients 2 and 5 showedthe greatest improvement, as determined by the mea-surements, followed by patient 1. Patients 1 and 4received the injection at the OO site; however, patients2 and 5 showed the greatest amount of improvement.

DISCUSSION

All patients were pleased with the results. No sideeffects (infection, bruising, edema, or loss of musclestrength) were reported or observed. One patient re-ported mild pain during the injection procedure. Theeffect began to be noticeable approximately 10 daysafter injection, with the maximum noticeable effectabout 14 days after injection. This effect was reported

miling photos with ruler at facial midline.

to be progressive but also reversible, lasting 3 to 6

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Polo 217

months. The patients received a supplemental dose 1month after the initial baseline dose in phase I.

The results obtained from phase III were highlyacceptable, and that dosage could be the optimal dosefor achieving the expected results. Clinical judgmentshould always be exercised when selecting the injectionsites. In severe cases, injecting at the OO site should beclinically considered, because the depressor septi nasimuscle, also associated with elevating the upper lipnear the midline, inserts into the fibers of the OOmuscle. The depressor septi nasi muscle thus has avertical pull component on the OO. The zygomaticusmajor muscle was not included in this study but will bein a subsequent study now underway.

Although surgical techniques have been reported inthe literature, they are not routinely used to treathyperfunctional upper lip elevator muscles resulting ina short upper lip and a concomitant gummy smile. Mostof the surgical correction currently used seems to beLeFort I maxillary osteotomies with impaction forskeletal vertical maxillary excess and gingivectomiesfor delayed passive dental eruption with excessivegingival display.

Because BTX-A is used frequently for the tempo-rary correction of perioral rhytides, care should betaken when injecting these anatomical areas in patientswith hypotonic, flaccid lips to avoid further muscleweakening and an esthetically unacceptable smile be-cause of excessive soft tissue covering the smile line.

CONCLUSIONS

Injection with BTX-A provides effective, mini-mally invasive, temporary improvement of gummy

Fig 2. Pretreatment and posttreatment photographs of

Table. Linear measurements: phase III

Patient no.

Measurement (mm)

�A (mm) �C (mm)A B C

1 Preoperative 8.0 5.0 4.0 4.0 �4.0Postoperative 12.0 5.0 0.0





See text for definitions of measurements A, B, and C.

study subjects.

American Journal of Orthodontics and Dentofacial OrthopedicsFebruary 2005

218 Polo

smiles for patients with hyperfunctional upper lipelevator muscles. The ideal dosage might be 2.5 U perside at the LLS, 2.5 U per side at the LLS/ZM sites, and1.25 U per side at the OO sites. Future studies areneeded to assess this treatment in a much larger sample.

I thank Gishlaine Alfonso, MD, neurologist, for herteaching and training of the electromyographicallyguided injection technique of BTX-A.

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botox excessive gingival display

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