August, 2011

Gingival Smile! Can BOTOX® Help?

Abstract:

The essential goal of dentists has been to achieve an esthetically pleasing smile irrespective of their specialty. The value of an attractive smile is undeniable. The framework of a smile is formed by the lips, teeth and gingiva. Excessive gingival display during smile is considered undesirable and less pleasing. Various treatment options are available for the correction of a gummy smile. Recently, the use of botulinum toxin (BOTOX® , Boot) has been advocated in the treatment of a gummy smile. Minimally invasive injections of BOTOX® into the hyperactive muscles of the upper lip, reduces the upward movement of the lip thus, resulting in a less gummy smile. In spite of a few pit falls, weighing the amount of psychological benefit to the patient, it is quiet a breakthrough in the field of cosmetic surgery in the treatment of gingival smiles.

Introduction:

A smile is the most recognized expression in the world and is the cornerstone of social interaction. A smile is considered as the universal friendly greeting in all cultures. The value of an attractive smile is undeniable. An attractive smile in modern society is often considered an asset in interviews, work setting, social interactions and even in the quest to attract a mate.

The essential goal of dentists throughout the world has been to achieve esthetically pleasing smiles irrespective of their specialty. Just as a nice smile can act as a powerful communication tool, an unpleasing smile can have an equally powerful negative impact.

 

One of the most common reasons for seeking orthodontic treatment is the excessive display of gingival tissue on smiling, usually referred to as a “Gummy Smile,” which is often esthetically displeasing. Some people with excessive gingival display are self conscious or embarrassed about it, and some are psychologically affected.

 

Etiological factors involved in the formation of a gummy smile can be, Skeletal (vertical maxillary excess), Gingival (passive eruption) or Muscular (hyperfunctional upper lip) and treatment options range from Le fort I osteotomy, crown lengthening, intrusion, myectomy to muscle resection, etc.

 

A non-surgical treatment would be advantageous. Recently a non-surgical and minimally invasive treatment option for correction of a gummy smile has been suggested, which is the use of BOTOX® .

 

BOTOX® is indicated when the gummy smile is due to a hyperfunctional upper lip elevator muscles (muscular capacity to raise the upper lip is higher than average).

Muscles responsible for upper lip movement during the smile are:

Levator labii superioris (LLS)

Levator labii superioris alaeque nasii (LLSAN)

Zygomaticus major

Zygomaticus minor

Depressor septii

 

What is BOTOX® ?

BOTOX® is the trade name for the neurotoxic protein botulinum toxin type A produced by fermentation of anaerobic bacteria clostridium botulinum. Type A is one of the seven distinct botulinum toxins produced by different strains of the bacterium. It is a stable, sterile, vacuum-dried powder that is diluted with saline solution, without preservatives, for injection.

The total “dose” of BOTOX® in each vial is always 100 units but different amounts of saline solution can be used with each vial depending on the intended use

 

Each vial of BOTOX®  contains

1        100 Units (U) of Clostridium botulinum type A neurotoxin complex,

2        0.5 milligrams of Albumin Human,

3        and 0.9 milligrams of sodium chloride in a sterile, vacuum-dried form without a preservative.

A brief history of BOTOX®

Over the last two decades, BOTOX®  has been approved by the Food and Drug Administration (FDA) for therapeutic treatments of eye muscle problems (in 1989), neck problems (in 2000), and excessive sweating (in 2004). At present, it is being investigated for treating other medical conditions. In 2002, the FDA approved Allergan’s BOTOX®  Cosmetic for the purpose of temporarily erasing facial lines.

 

Mechanism of Action

BOTOX® decreases muscle activity by blocking overactive nerve impulses that trigger excessive muscle contractions or glandular activity

 

Phase I – Nerve-Muscle Communication is Blocked

BOTOX®   blocks the transmission of overactive nerve impulses to the targeted muscle by selectively preventing the release of the neurotransmitter acetylcholine (ACH) at the

neuromuscular junction, temporarily preventing muscle contraction. This is primarily a local effect. BOTOX® may also prevent the release of pain-stimulating neuropeptides in peripheral nerves.

 

A) Binding (fig 1):

The heavy chain portion of the active ingredient in BOTOX® binds to the cell membrane of the motor nerve via an unidentified high-affinity “acceptor” molecule. This high-affinity binding action allows for efficient uptake of BOTOX® by the motor nerve and facilitates selective, targeted treatment at the injection site.

B) Internalizing(fig 2):

After binding, the BOTOX®   protein molecule passes through the cell membrane of the motor nerve and into its cytoplasm via a process called endocytosis. It is here that the enzymatic component (light chain) of the BOTOX® protein molecule is activated.

C) Blocking(fig 3):

Inside the motor nerve, the light chain of the BOTOX® ® protein molecule cleaves apart a protein (called SNAP25) that enables vesicles which store the neurotransmitter acetylcholine to attach to the cell membrane. Cleaving SNAP25 prevents these vesicles from fusing with the membrane and prevents the release of acetylcholine into the neuromuscular junction (the space between the motor nerve and the muscle).

Thus, nerve impulses that control muscle contractions are blocked decreasing muscle activity. Cleaving SNAP25 also blocks release of neuropeptides involved in the transmission of painful sensations (including substance P, glutamate and calcitonin gene-related peptide, or CGRP), theoretically reducing pain sensitization of peripheral nerves. This may be how BOTOX® reduces the neck pain associated with cervical dystonia, although the exact mechanism of action is unknown.

 

Phase II – Nerve-Muscle Communication is Restored

The effect of BOTOX® is generally temporary. Previous nerve impulse activity and associated muscle contractions resume over the course of a few to several months, depending on the individual patient and the indication for which they are being treated.

A) Nerve Sprouting (fig 4):

New nerve endings sprout and connect to the muscle after the original nerve ending

is blocked, renewing the ability of the nerve to cause muscle contractions.

B) Original Nerve Connection Re-established (fig 5):

Eventually, the new nerve sprouts retract and the original nerve ending regains its

function, suggesting that treatment with BOTOX®  does not permanently alter the

neuromuscular junction.

Indications:

1        Strabismus

2        Cervical dystonia,

3        Blepharospasm and

4        Hemifacial spasm,

5        Hyperfunctional larynx,

6        Juvenile cerebral palsy

7        Spasticity

8        Pain and headache

9        Occupational dystonia and writer’s cramp,

10    Cosmetic treatment of hyperfunctional facial lines.

11

Uses in dentistry:

1        Tempromandibular disorders

2        Massetric hypertrophy

3        Hemifacial spasm

4        Myofacial pain

5        Bruxism

6        Trismus, sialorrhea

7        Retraining muscles during orthodontic therapy, in patients with a very strong musculature.

8        Training the patient to get used to new dentures, especially in patients with strong irregular muscle contractions, who have been edentulous for a long time and have old dentures and they are significantly overclosed.

9        Jaw line contouring by injecting into masseter muscle thus weakening it and some bulk of this muscle is reduced, resulting in a more tapered jawline.

 

 

 

 

Procedure for injection:

For correction of a gummy smile, BOTOX® is injected into the hyperactive elevator muscles of the lip blocking excessive contractions and, thus, preventing the lip from being pulled too far up while smiling. It will be important for the patient to avoid taking aspirin or related products, such as ibuprofen (eg, Advil) or naproxen if possible after the procedure to keep bruising to a minimum.

Prior to injection, reconstitute vacuum-dried BOTOX® with sterile normal saline without a preservative; 0.9% Sodium Chloride Injection is the only recommended diluent.

Draw up the proper amount of diluent in the appropriate size syringe, and slowly inject the diluent into the vial. BOTOX® should be administered within four hours after reconstitution. During this time period, reconstituted BOTOX® should be stored in a refrigerator (2° to 8°C). Reconstituted BOTOX® should be clear, colorless and free of particulate matter.

 

 

Mario Polo (AJODO 2005) has advocated injection of BOTOX® at LLS, LLSAN, LLS/ZM overlap and in severe cases at depressor nasii & OO also. The ideal dosage might be 2.5 U per side at the LLS & LLSAN, 2.5 U per side at the LLS/ZM sites, and 1.25 U per side at the OO sites.

Very recently Hwang et al; Yonsei University College of Dentistry, Seoul, Korea (Angle Orthodontist 2009) have proposed an injection point for botulinum toxin-A, and named it as YONSEI POINT and they recommend a dose of 3U at each Yonsei point

Yonsei point is located at the centre of the triangle formed by (fig 6):

1        levator labii superioris [LLS],

2        levator labii superioris alaeque nasi [LLSAN],

3        and zygomaticus minor [ZMi].

How often do patients need to return for additional injections?

Effect of BOTOX®  is seen within 5-10 days and lasts about 6 months, with a range of 4 to 8 months, at which time the patient can return to repeat the process. It is important not to give injections prematurely (before the effects of the treatment have worn off), as this can result in a buildup of antibodies to BOTOX® that would dilute the effect of further treatments.

Contraindications

1        During pregnancy or while breast feeding

2        Presence of inflammation or infection at the site of proposed injection

3        Anyone with known hypersensitivity or allergies to human albumin, BOTOX®  toxin,  or saline solution.

4        Anyone with known motor neuropathy, neuromuscular disorders such as amyotrophic lateral sclerosis, myasthenia gravis, Lambert-Eaton Syndrome, muscular dystrophy, multiple sclerosis etc.

5        Anyone taking Aminoglycoside antibiotics because aminoglycosides may interfere with neuromuscular transmission and potentiate the effect of BOTOX®  therapy.

6        Anyone taking Calcium Channel Blockers

 

Side effects

1        Nausea

2        Localized pain

3        infection

4        inflammation

5        tenderness

6        swelling

7        redness, and/or

8        bleeding/bruising

Disadvantages

1        Short term effect

2        Asymmetrical/unnatural appearance of smile sometimes due to improper injection technique

3 Cost factor

Advantages

1        Psychological benefit to the patient

2        Minimally invasive

Should dentists administer BOTOX®  therapy?

With plastic surgeons, dermatologists, internal medicine physicians, obstetricians-gynecologists, ophthalmologists, podiatrists, nurses, physician’s assistants, and medical aestheticians (who may not even be medically trained) delivering BOTOX®  to patients in the oral and maxillofacial areas, it is certainly time to recognize that dentists can be just as proficient in injections than any of these healthcare providers as dentists have much greater expertise in the oral and maxillofacial areas and are also trained to be experts in the muscles of mastication and the muscles of facial expression, which routinely receive these treatments.

Conclusion:

It is time to broaden our horizons as a profession and use all of the tools available to us. BOTOX® therapy is a conservative, minimally invasive treatment that can expand our therapeutic options for the benefit of our patients and is a natural progression of where we are going in the dental industry. These procedures are easy to accomplish by general dentists with proper training.

® mark owned by Allergan, Inc.

References:

1.      Mario polo, Botulinum toxin type A in the treatment of excessive gingival display; AJO DO 2005, vol127 no.2 ,pg 214-218.
2.      Hwang et al, surface anatomy of the lip elevator muscles fort he treatment of gummy smile using botulinum toxin.Angle Orthod 2009, vol 79, no.1,pg 70-77.
3.      Mario Polo,Botulinum toxin type A (BOTOX® ) for the neuromuscular correction of excessive gingival display on smiling (gummy smile) AJO DO 2008, vol 133 no.2, pg 195-20

Authors:

Dr Prashanth Kamath; MDS

Professor & Head

M-+919886041212

 

Dr Lavesh Vati Deshwal;

Consultant orthodontist,

Ahmedabad-India

M +919879926009

 

Dr Harsh Pandey

Consultant Orthodontist

Ahmedabad-India

M-+919586558299