Written by Dr. Dennis Hartlieb
February 2023

Canted Smile Guide:
7 Reasons for the Unaesthetic Canted Smile and What Cosmetic Dentists Can Do to Treat Them

When your patient presents with a canted smile, your goal is to find the underlying cause of misalignment and create a treatment plan targets the root of the problem. This blog examines potential causes of the canted smile and conservative treatment options available.

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(Read time 8 - 10 minutes)

What Causes a Canted Smile?

In this article, you will learn about what could be causing an unaesthetic canted smile, and we will consider why our smiles matter and what we as dentists can do to help patients who have crooked smiles.

We interviewed DOT Premium Members about treatment recommendations for the canted smile. View the full survey here.

7 Factors That Can Contribute to Unaesthetic Canted Smiles

  1. Medical Indications When Smile Changes
  2. Lip Asymmetry
  3. Gummy Smiles and What to Do about Them
  4. Uneven Wear on Teeth
  5. Missing or Undersized Teeth
  6. Poor Occlusion / Bad Bites
  7. TM Joint Issues

Click here to scroll ahead to the factors to consider and what dentists can do.

Considering Smiles: A Little Background About Me

When I was a kid, summers were midwestern slow. There were no overnight camps or sports camps, no family cottages on a dreamy midwestern lake. Nope, just hot and humid summer days with a familiar morning ritual; a morning breakfast of Cap’n Crunch or some other cereal packed with 8 or more essential vitamins with delicious whole milk!
 
My best friend, Donny, lived a couple of blocks away, and we’d fill our days the best way we knew how while living in suburban Detroit. We’d ride our bikes exploring the limitations of our urban world.
 
Back at Donny’s place, we’d find things to do to stay out of our mothers’ hair until dinner time. We’d work on our fastballs, dig for worms… with plans for more of the same for the next day, and the next day after that.
 
One week, Donny’s family went ‘up north’ as we say, on vacation, and I was left alone.

How does this relate to treating canted smiles and creating esthetic smiles?

Let me tell you... (Or click here to get to the treatment considerations!)
On this particular week that Donny had abandoned me, I was feeling a bit grumpy about the unfair twist that life had dealt me. My buddy was gone, my older siblings treated me like a parasite, my parents also had no time for 9-year-old me, as they were busy living the life of those who have to raise a family and make a living… but there was Ted.
 
Ted was an elderly neighbor who lived across the street. I suspect he was probably in his sixties, having retired from his career working for one of the ‘Big 3’ automotive factories (General Motors, Ford and Chrysler).
 
Ted was sitting on his front porch, a one-story suburban ranch with aluminum siding – classic 1950s Americana, with white trim and faux black shutters. The lawn was flat and finely manicured - the product of civic pride and a boat-load of time to do one’s part to keep the neighborhood clean and respectable.
 
Ted’s house had a one-car, detached garage. It was painted white to match the house. The garage door was a one-piece door that opened and closed all as one. As it turns out, this simple white, suburban garage door would serve perfectly as a canvas for Den and Ted’s most excellent adventure!
 
Ted decided that this week would be a good week to paint his garage door. So Ted said to me, “Den, how about we paint a big smiley face on the garage?”
This round yellow smiley face has become the most familiar of emojis, but in the 1970s, it was a symbol to speak of the good in the world.
 
After a little Google research, it seems that the yellow smiley icon was born in 1963 in Worcester, Massachusetts, when the graphic designer Harvey Ball was approached by State Mutual Life Assurance Company to create a morale booster for employees. The smiley face emoted “have a happy day.” The yellow circle with the simple, uncomplicated curve of the smile, sent the most assuring and comforting message – smile and be happy.

The truest form of the smiley face works because of its simplicity, and its balance and symmetry.
 
All of this historical commentary on my week as a kid in Detroit leads us to the topic of the smile, and more directly, the canted smile.

In today’s blog post, I will discuss what causes the canted smile, and options for correcting the mal-aligned smile.
Canted Smile: A canted or crooked smile refers to a smile that is not level across the horizontal plane of the face. It is a smile that is tilted or slanted. 

Seven Factors Contributing to Canted Smiles

FACTOR ONE

Medical Considerations

The first question to ask if someone is bothered by a canted smile is if the uneven smile changed suddenly.

Medical issues, such as Bell’s palsy or more significantly, a TIA (transient ischemic attack), or a stroke, can cause muscle paralysis, commonly unilateral or one-sided on a person’s face. Any issues along these lines require attention from medical personnel and appropriate medical intervention.

However, if the smile imbalance has been apparent for years, or there has been a slow change in the canted smile, there are other issues that we should consider.
Figure out the etiology then make [a] diagnosis and treatment plan.

Kevin L. Hicks, DDS
DOT Premium Member, Survey Response
FACTOR TWO

Lip Asymmetry

The second, and most common reason for a canted smile is when the muscle pull of the lips is not coordinated, or balanced.

I frequently see patients in my dental practice, that when they smile, one side of the lip pulls higher (for the upper lip) or lower (for the lower lip) (Image 1 & 2).

Most of my patients are not even aware of this imbalance when they smile.

Image 1. Example of patient smile with upper lip pull.

Image 2. Example of patient smile with lower lip pull.

I had a patient many years ago, Gail, who was not aware of her lip asymmetry when she smiled. The muscles of her lower lip, on the left side, did not exhibit the same pull as the muscles on her right side, creating asymmetry in her smile.

As a younger, less experienced clinician, I did not notice this ‘lip pull’ and thus, did not bring it to Gail’s attention. It was only AFTER we finished her dental reconstruction that she noticed the lip asymmetry.

Gail and I were both pleased with the results of the dentistry – single unit crowns on natural teeth and dental implants on all of the upper teeth and some supportive dentistry on the lower arch.

It was only after we finished with the dental treatment that Gail noticed that her left lower lip hung down when she smiled.

Pro tip: Before and After photos can support you as the clinician in many ways, including instances where patients believe that your dentistry caused a dental problem.

Crazy as it might sound, it turns out, Gail was convinced that her lip asymmetry was ‘due to all those impressions of her teeth that I took’, and was so upset with me, that she refused to pay her final balance.

Pro tip: Before and after photos can support you as the clinician in many ways, including instances where patients believe that your dentistry caused a dental problem.

Gail thought the alginate and PVS impressions that I took to perform the dentistry caused the lip asymmetry. This is typically where I would place the sad face emoji …so much for ‘have a happy day’!
Take very accurate records, and address the chief complaint.

Antonela Schroeder, DMD
DOT Premium Member, Survey Response
At the time when I treated Gail, we did not have a conservative treatment option for people with asymmetric lip pull.

In today’s world, treatment for excessive lip pull can be as simple as Botox therapy. As with any Botox treatment, it will need to be repeated when the effect of the medication wears off, typically about 3-4 months.

This conservative cosmetic treatment can make all the difference for a patient, creating harmony, symmetry and balance in their smile.
FACTOR THREE

Gummy Smile

If your patient shows the gum line of their upper teeth when they are smiling or laughing, it is important that the gum lines be level and symmetrical. 

Example of patient with upper gum line showing, revealing a balanced smile.

A patient may not show much of their gum tissue when smiling, but even a small display, if the gum lines of their teeth are not level, will result in an unaesthetic smile. 

Example of a patient who shows un-level gingival margin heights and canted smile.

There are multiple reasons for a gummy smile, but if a patient has a gummy smile, a situation where they show a lot of gum tissue, or gingiva as we call it in the business, there are a few simple rules to follow.

Simple Rules to Follow for Patients with a Gummy Smile:

1. The Patient Seeking Treatment:

If the patient does not like their gummy smile, we can again consider Botox therapy in the upper lip to reduce the muscle pull. When the patient smiles after the Botox treatment, less upper lip muscle pull would result in less movement of the lip to minimize the upper gum tissue exposed.

2. The Patient not Seeking Treatment or Other Treatment Failed: 

If the patient does not want to alter the amount of lip pull, or if even with Botox therapy the gum lines are apparent, then the dentist must manage the gum lines of the upper teeth to be certain that the gum levels are balanced.
 
When looking at a smile, the gum lines of the central incisors and the canines should be at the same horizontal level. The lateral incisors will either be at that same level, or slightly coronal (1 millimeter or so) to the imaginary horizontal line connecting the gum height of the central incisors and the canines. 

This illustration demonstrates gum lines that are at the same horizontal level.

The bicuspids again should either be at that same horizontal line, or slightly coronal to the canine/central incisor horizontal line, which is more typical. The maxillary first molar’s gum line should again be on that horizontal line. Below is an illustration of an ideal smile with appropriate gingival, or gum, levels.

In this second illustration below, I’ve altered the gum heights on the left side of the smile. Notice how the smile now looks ‘canted’ due to the gum tissue heights being asymmetric. 

This illustration shows the same smile with altered gum heights, resulting in a canted appearance. 

To manage the canted smile caused by overexposed gingiva in clinical practice, the dentist has several treatment options: 

  1. Raise the gum tissue on the left side to equal the gum tissue height on the right side.
  2. Add gum tissue to the patient’s right side to lower the gum tissue to balance the right and left side.
  3. Use orthodontics (braces) to move the teeth (left side teeth intrude, right side teeth erupt).

Option #1
Option one would require esthetic crown lengthening, or what we refer to in our practice, as a ‘Gum Lift.’ The gum lift can be provided by the restorative dentist, though the patient may need to be treated by a gum specialist, a periodontist. 

The main issue to consider with the gum lift option is if the final restorative margin will be on root surface, or on enamel, and how this resultant tooth structure will influence if restorative treatment will be needed. 

Option #2
Option two would be appropriate if there is gum recession on the teeth that are too long (in this case, the right side teeth). Gum grafting is a technique traditionally done by a periodontist wherein gum tissue from the patient’s roof of the mouth is ‘grafted’ into the area where gum tissue is needed. 

As an alternative to taking gum tissue from the palate, there are situations where a ‘donated’ tissue from a tissue bank can be used to replace the missing gum tissue (Alloderm is the most common). 
Alloderm: A dermal matrix derived from human donor tissue that can be used for gum grafting.
Option #3
Option three involves moving the teeth to balance the gum levels. When teeth are moved, the gum tissue follows the tooth. So, either using traditional braces, or clear retainers, like Invisalign, teeth can be moved up or down, to move the gum tissue to a more ideal position.

There are considerations with each of these treatment options, and an understanding of the patient’s individual tooth anatomy, occlusion and tissue health must be part of the diagnosis and treatment plan to provide a healthy and cosmetic treatment solution.
FACTOR FOUR

Uneven Wear on Teeth

It is not uncommon for people to grind their teeth. Bruxism can occur when people sleep (nocturnal) or while they are awake (diurnal). In my experience, patients often have their own unique tooth grinding motion. 

Some patients will grind their lower jaw evenly, side-to-side, while some people will grind their teeth front-to-back, and others will grind every which way. There are also patients that have a preferential side for grinding their teeth – that is, they may favor just grinding to their left side or to their right side. 

With these patients who prefer one side, it is not uncommon to see that the edges of their teeth are different from one side to the other. 

Example of patient with uneven wear patterns on teeth, resulting in edges of the teeth that are different from one side to the other.

The teeth that are on the ‘grinding’ side will be shorter, due to the wearing away of the enamel and dentin of the tooth structure. As this process of grinding continues, there will become an apparent canted smile, or what it is referred to as a cant in the esthetic plane. 

To treat these wear cases, restorative dentistry will need to be employed. The worn teeth will need to be added to the incisal edges or cusps to recreate the normal tooth form. This can be completed with either direct resin bonding (composite), or with indirect techniques such as porcelain veneers, porcelain onlays, or porcelain crowns. 

It is critical that the dentist manages the occlusion (bite) to minimize the risk of failure of the restorative material. The patient should likely be evaluated for a compromised airway (i.e. sleep apnea), coached on eliminating daytime grinding habits, and provided a night time appliance to wear while sleeping to minimize tooth forces from clenching and grinding.
Evaluate airway to eliminate any restrictions, ie. look at cause first. If [you] don't change [the] environment, [you] will eventually have [the] same progressive outcome.

Deborah Fung, DDS, MAGD
DOT Premium Member, Survey Response
FACTOR FIVE

Missing or Undersized Teeth

Patients with missing teeth can develop a canted smile for several reasons. 

If posterior (back) lower teeth are missing, the upper back teeth will erupt (move downward) due to the lack of occlusal (bite) stability. As the upper teeth erupt, the gum tissue, which is attached to the teeth, will also erupt resulting in a canted, or crooked, smile. 

If a front tooth is missing, the other teeth around that front tooth will likely shift to fill the space, causing a canted smile. The common reasons for missing front teeth are from trauma, periodontal disease (gum disease), or the tooth is congenitally missing (never formed). 

If posterior (back) lower teeth are missing, the upper back teeth will erupt (move downward) due to the lack of occlusal (bite) stability. As the upper teeth erupt, the gum tissue, which is attached to the teeth, will also erupt resulting in a canted, or crooked, smile. 

There are many options for replacing the anterior missing tooth.

Misshaped, undersized, or missing teeth can also cause the smile to be out of balance.

Example of patient with missing and undersized teeth that affect the smile.

Approximately 2.5% of the population has undersized, or maxillary, peg lateral incisors. Orthodontics is commonly necessary to appropriately reposition the teeth to create ideal spacing for these patients to provide a balanced and harmonious smile.
Write your awesome label here.

Watch as Dr. Hartlieb adds the light microfill layer to his peg lateral restoration in the Peg Lateral Hands-On One-Demand course.



FEATURED RESOURCE

The Ultimate Finishing and Polishing Guide for Anterior Composite Restorations 

Check your inbox! We sent the file to your e-mail address. You may also download the polishing guide now.
FACTOR SIX

Poor Occlusion / Bad Bites

Bad bites can cause teeth to be in non-ideal positions, resulting in canted smiles. 

Cases where there is bite instability (Image 7), or when teeth are in crossbite (Image 8), can prevent teeth in the upper or lower arches from erupting into their normal positions. 

Image 7. Example of bite instability.

Image 8. Example of crossbite. 

In this patient case where there is a posterior crossbite, the upper left teeth are not at the same level as the other teeth in the upper arch, creating an unlevel and unaesthetic smile. When teeth are overlapped, this can also give a look of the smile being canted (Image 9). 

Image 9. Example of overlapping teeth.

FACTOR SEVEN

TM Joint Issues

The mandible, or the lower jaw bone, houses the teeth in the front and has two extensions, called the ramus. The condyles are the final extension of the ramus that sit in the temporomandibular (jaw) joint. Ideally, the ramus and condyles are equal in size and length bilaterally.

If a patient has a degenerative joint disease in one of their TM joints, this will cause breakdown of one of the condyles. As the condyle shrinks in size, the patient’s chin will shift in the direction of the joint breakdown (see the illustration and the image below).

Illustration demonstrating effect of degenerative joint disease.

Example of patient with TM joint issues impacting smile. 

Frequently, but not always, this will cause the smile to be affected as well. There may be only soft tissue changes to the face, but bite and structural changes can occur as well, creating a cant, or angled maxillary occlusal plane. 

The smile esthetics can be improved in these cases with restorative dentistry, or with a combination of restorative dentistry with orthodontics and periodontics. For many patients, however, oral surgery may be required to manage the damaged joints, as well as improve the tipped, or canted bite plane. 
Write your awesome label here.

Watch this clip from our Occlusion Made Easy course where Dr. McKee demonstrates on a patient how to measure and assess joint movement.

Final Thoughts about Canted Smiles

I use the smiley face emoji probably too much in my communications. I’ve tried using the colon parenthesis approach, but it just doesn’t give the same vibe as the yellow disc and black markings.

It is the symmetry of this iconic, irreplaceable, unflappable yellow circle with the simple concave smile that for that instant, that moment, makes us feel safe, and reminds us to ‘have a happy day.’

Symmetry, balance, and harmony are critical when creating beautiful smiles for our patients. Recognizing the 7 factors that can lead to the canted smile, and managing these issues, is essential to providing our patients a radiant, natural, beautiful and happy smile.



Dennis Hartlieb, DDS, AAACD

DOT Founder

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