Dental Issues in Noonan Syndrome

Brett | Jun. 8, 2021

There is not a lot of literature available on dental manifestations in Noonan Syndrome (NS) and we don’t know with any certainty if many of the dental issues discussed in this Blog occur at a greater prevalence among people with NS than the non-NS population. What we aim to do in this Blog Post is discuss the main dental issues that have been reported in individuals with NS so that individuals with NS and their caregivers can be aware of them and share this information with their relevant healthcare providers (e.g. Dentist, Orthodontist etc).

Skeletal Differences

Open bite

Open bite is a type of malocclusion that is majorly characterized by a vertical gap. This gap is usually visible between the front teeth. When the teeth from the two jaws are completely in contact, the front teeth from the upper and lower jaws cannot meet. Open bite can cause problems with eating, speech and cause uneven wear and pain.


Many treatments are available for open bite – a dentist will make specific recommendations based on the person’s age and whether they have adult or baby teeth. Treatment methods include behaviour modification, mechanical treatment such as braces and/or headgear and in some cases, surgery may be required.

Cross Bite

A crossbite is a malocclusion (bite problem) where the top teeth and bottom teeth do not come together or bite in the correct position. Crossbites can be caused by either tooth position, jaw position, or a combination of both. They can occur in the front teeth (called an anterior crossbite or underbite) or in the back teeth (called a posterior crossbite).

Crossbites can cause jaw growth problems in children and adolescents. Crossbites can be linked to a narrow upper jaw and palate which can cause bite and breathing issues. As always, early intervention helps prevent future problems and crossbites of front teeth can cause tooth chipping or gum problems if untreated.

In kids and teens, posterior crossbites (crossbites in the back teeth) are often times treated by broadening the upper teeth and jaw. This can be done with special appliances or braces depending on the person. Braces or retainers may be needed to correct crossbites and in rare cases, crossbites are so severe that jaw surgery may be needed.


Class Malocclusions

Class I, II and III malocclusions (bite problems) have been reported in people with NS.

Class I malocclusions occur when the upper and lower jaws are in their proper position, but overcrowding or excessive spacing are causing issues.

Class II malocclusions occur when the upper teeth are positioned too far ahead of the lower teeth. Depending on whether there is a vertical or horizontal protrusion, this form of malocclusion is commonly referred to as overbite. Almost always it is the retrusive lower jaw that is causing this type of malocclusion.

Class III malocclusions occur when the lower teeth are too far forward, often overlapping with the upper front teeth. This is commonly referred to as an underbite. A protrusive lower jaw or a retrusive upper jaw can be the cause.

A severely misaligned jaw can lead to stress and pain in the teeth and jaw leading to headaches. Even an uneven bite can put enough pressure on the TMJ (temporomandibular joint – the joint that acts as the hinge for your jaw) to lead to chronic headaches, which is why properly aligning the jaw and straightening the teeth need to go hand in hand.

Some people with mild malocclusion will not require any treatment. However, if the malocclusion is moderate to severe, your orthodontist may recommend braces to correct the position of your teeth and avoid potential pain, discomfort, and oral complications.

Deep Bite

Deep bite has also been noted in NS individuals. Deep overbite is when the upper front teeth almost completely overlap the lower front teeth. It has an impact on facial aesthetics, often the lower teeth line or lower dental arch has a ‘bell-shape’, where the lower front teeth rise up much higher than the back teeth and sometimes it is so pronounced that the top edges of the lower teeth bite into the gum tissue in the roof of the mouth. This can be a very serious issue and can leads to loss of the front teeth.


Most patients with a deep overbite have small looking chins. The chin is pushed back by the bad bite, which makes it look smaller than its actual size. Deep overbite correction or treatment is generally needed when the upper teeth overlap the lower teeth and the lower jaw is pushed back towards the patient’s ears.


For an overbite braces can move the patient’s front, top teeth and help them more naturally match up with the patient’s bottom teeth. Most patients who have an abnormal bite are identified by the age of six, and most orthodontists recommend these patients engage in the treatment between the ages of eight and fourteen. Jaw surgery is almost always combined with braces to correct a skeletal overbite. Treatment should be started as early as possible to minimize the severity of the issue.


Enamel Defects

Developmental defects of enamel (DDE) in people with NS have been reported in the literature. These defects can be loss of thickness of the enamel or loss of enamel covering. Loss of enamel increases the risk of dental caries.

Dental caries is the medical term for tooth decay or cavities. It is caused by dissolution of tooth minerals by bacterial acids. Many different types of bacteria normally live in the human mouth. They accumulate (along with saliva, food particles and other natural substances) on the surface of the teeth in a sticky film called plaque. Plaque forms especially easily in cracks, pits or fissures in the back teeth; between teeth; around dental fillings or bridgework; and near the gum line. Some of the plaque bacteria convert sugar and carbohydrates (starches) in the foods we eat into acids. These acids dissolve minerals in the surface of the tooth, forming microscopic channels that get larger over time.

The damage can occur anywhere the tooth is exposed to plaque and acid, including the hard outer enamel on the tooth crown or the unprotected root of the tooth that has been exposed by gum recession. Caries can penetrate the protective enamel down to the softer, more vulnerable dentine (main body of the tooth) and continue through to the soft tooth pulp and the sensitive nerve fibres within it. The pain associated with cavities may be caused by inflammation initiated by bacteria and an imbalance of fluid levels in the tubules inside the dentine.

Early caries may not have any symptoms. Later, when the decay has eaten through the enamel, the teeth may be sensitive to sweet foods or to hot and cold temperatures. White spots, indicating early caries that has not yet caused cavitation, may be reversed if acid damage is stopped and the tooth is given a chance to repair the damage naturally. Caries that has destroyed enamel cannot be reversed. Most caries will continue to worsen and deepen and with time, the tooth may decay down to the root. The amount of time the breakdown takes will vary from person to person. Caries can progress to a painful level within months or it can take years to reach that stage.

Cavities can be prevented by reducing the amount of plaque and bacteria in the mouth and with careful attention to diet. The best way to do this is by daily brushing and flossing and you can reduce the amount of acid in your mouth by eating sugary or starchy foods less frequently during the day. Your mouth will remain acidic for several hours after eating, so snacking throughout the day is more likely to lead to caries than avoiding between-meal snacks. Chewing sugar-free gum can counteract the acidity that occurs after eating.

Teeth can be strengthened by fluoride. A dental professional can evaluate your risk of caries and then suggest appropriate fluoride treatments. In children, new molars can be protected by having the dental professional apply a sealant as soon as the teeth come fully into the mouth.

The standard treatment for caries that has progressed to enamel cavitation is to fill the tooth. After the dental professional removes the decayed material in the cavity (usually following the use of anaesthesia to block the pain), the cavity is filled.

If a cavity is large with extensive breakdown, the remaining tooth may not be able to support the amount of filling material that would be needed to repair it. In this case, the dentist will remove the decay, fill the cavity, and cover the tooth with an artificial crown.

Sometimes the crown of the tooth may be able to be restored but there is more damage to the pulp of the tooth. In these cases, the dentist may refer you to a dental specialist called an endodontist for root canal treatment. In this procedure, the endodontist removes the tooth’s pulp and replaces it with an inert material. In most cases, the tooth’s natural crown will need to be replaced with an artificial crown.

Dental Anomalies


A molar tooth in which the body of the tooth appears to be enlarged at the expense of the roots is diagnosed as having taurodontism. It occurs in varying degrees and is classified in order of severity for hypotarodontism (mild) to hypertaurodontism (severe) (as pictured).

Taurodontism has been reported in people with NS and although it doesn’t require treatment it is important to consider when having some dental procedures especially those involving root canal treatments


Hypodontia has been noted in NS individuals and refers to the absence of one or more permanent teeth (excluding the molars). Missing teeth can affect the ability to chew and confidence in appearance and an altered smile. Additionally, missing teeth may pose functional concerns, as the other teeth in the mouth can move into the empty space and shift how the teeth come together. Ultimately, hypodontia can lead to problems with speech, gum damage and insufficient bone growth.

In treating hypodontia, your dentist will likely recommend replacement options, such as removable partial dentures, fixed bridges or dental implants. Sometimes, orthodontic treatment can also be used to close gaps between teeth.


Hyperdontia is a condition that causes too many teeth to grow in your mouth. These extra teeth are sometimes called supernumerary teeth. They can grow anywhere in the curved areas where teeth attach to the jaw. This area is known as the dental arches.

The 20 teeth that grow in childhood are known as primary, or deciduous, teeth. The 32 adult teeth that replace them are called permanent teeth. There can be extra primary or permanent teeth with hyperdontia, but extra primary teeth are more common.

Supernumerary teeth can cause problems such as overcrowding, noneruption or delayed eruption of adjacent teeth, teeth displacement, cyst formation, nerve pain and reduced confidence due to changing the appearance of one’s smile or face.

Hyperdontia is easy to diagnose if the extra teeth have already grown in. If they haven’t fully grown in, they’ll still show up on a X-Ray. A Dentist may also use a CT-Scan to get a more detailed look at the mouth, jaw, and teeth.

While some cases of hyperdontia don’t need treatment, others require removing the extra teeth. Your dentist will also likely recommend removing the extra teeth if there is an underlying genetic condition causing the extra teeth to appear, the individual can’t chew properly, feels pain or discomfort due to overcrowding, or has trouble brushing or flossing because of the extra teeth which could lead to decay or gum disease.


Double Tooth

Some children develop double teeth and this has been reported amongst NS individuals. There are two causes of this condition: germination and fusion.

Gemination occurs when one tooth splits into two, but they remain attached to each other and develop together. If the geminated teeth are counted as one tooth, there are a normal number of teeth.

Fusion occurs when two teeth join into one and looks similar to gemination. However, if the fused teeth are counted as one tooth, the child will be missing a tooth.

Gemination and fusion are most common in the upper front teeth, but they can also occur in the lower teeth. Gemination is more common in the upper teeth, while fusion is more common in the bottom teeth. They can occur in the permanent teeth, but that is much less common.

Germination and fusion can cause problems, such as crowding, atypical spacing, and problems or delays in the eruption of permanent teeth. A paediatric dentist should monitor the permanent teeth to make sure they emerge normally. It may be necessary to remove the double tooth to allow that to happen.

Sometimes there are no permanent teeth under a fused double tooth, but that is rare. A dentist can take an x-ray to check the permanent teeth. Geminated and fused teeth can have a deep groove between them that is susceptible to cavities since brushing is difficult. A dentist may want to put a sealant on the tooth to prevent a cavity from developing.

Gemination and fusion can sometimes be treated by shaving down and smoothing the double tooth to make it less noticeable. This will not be possible if the pulp is too close to the surface. Under rare circumstances, the dentist may be able to divide the tooth with surgery. This works best with fused teeth that have separate roots and pulp chambers. Both teeth will need to have root canals. Some parents choose not to treat a double tooth since their child will ultimately lose it and have it replaced by permanent teeth.


As discussed in this Blog there are many dental manifestations that may present in people with Noonan Syndrome. Oral healthcare for NS patients should begin in the first year of life and routine dental surveillance can prevent functional, aesthetic and painful dental problems from developing.

The identification and management of any structural anomalies such as those mentioned in this Blog should be considered and the prevention of dental caries is important to prevent subsequent problems. The higher incidence of bleeding disorders must also be remembered by dental health care professionals when planning surgical intervention.



Anthonappa, R., King, N.M.(2019). Oral and dental manifestations in Noonan Syndrome. In A. Bhangoo (Ed.). Noonan Syndrome: Characteristics and Interventions. Academic Press.


(2020, May 31). Deep overbite.


(2020, May 31). What is an open bite?


(2020, May 31). Open bite.


(2020, May 31). Cross bite.


(2020, May 31). What is a malocclusion?


(2020, May 31). Dental Caries.


(2020, May 31). What is hypodontia?


(2020, May 31). Hyperdontia: Do I need to have my extra teeth removed?


(2020, May 31). What causes Double Teeth?



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