Childhood Oral Habits and their Effects

Kimberly Martins, M.A. CCC-SLP
March 10, 2024

Babies, toddlers and young children all have a variety of oral habits. Some last an appropriate amount of time and some last longer than they should. Many children will cease to use oral habits that are no longer appropriate by themselves and others will need help from their parents. Today’s discussion will focus on the most common oral habits seen in young children and their possible effects (positive and negative).

Common oral habits in children consist of mouth breathing, pacifier use and thumb sucking.  As a speech-language pathologist I have seen children with a wide variety of these oral habits. I have targeted therapy goals related to mouth breathing and an open mouth posture as well as counselled parents on pacifier use and thumb sucking. We will see along our discussion that these oral habits tend to have similar effects.

Open Mouth

Your resting mouth position refers to the position of your oral structures such as your tongue, lips and jaw at rest (i.e. when you are not actively speaking, eating, etc.). An open mouth resting posture means that your mouth is open at rest. This can be due to numerous factors. Many times the mouth is open at rest because people breath through their mouths instead of their nose. However, you can also have an open mouth resting posture while breathing through your nose. We will discuss some of the reasons as to why some children (even adults) adopt an open mouth resting posture and its effects.

Proper Mouth Resting Posture

Mouth is closed

Lips are together without strain

Breathing through the nose

Tongue is relaxed up along the top palate

Tongue tip is behind the top front teeth (NOT pushing against them)

Improper Mouth Resting Posture

Mouth is open

Breathing through the mouth

Lower jaw is hanging forward

Tongue is at the bottom of the mouth

Tongue is sticking out or pushing against the top front teeth

Causes of an open mouth

  • Mouth breathing
  • Incompetent lip closer (weak lip muscles)
  • Low oral muscle tone (weak muscle strength – lips, tongue, jaw)
  • Short labial frenum (i.e. lip tie)
  • Short lingual frenum (i.e. tongue tie)
  • Upper airway restrictions (allergies, enlarged tonsils or adenoids, chronic colds/congestion, asthma, deviated nasal septum)
  • Thumb sucking

Effects of an open mouth

  • Dental issues (caries, gingivitis, malocclusions – teeth closing together is affected)
  • Physiological changes in the face (long face syndrome, protruding lips/jaw, etc.)
  • Tongue thrust (reversed swallowing pattern)
  • Head and neck posture
  • Orthodontic treatment will be more difficult or unsuccessful
  • Speech (improper articulation of sounds such as t, d, n, l, s, z, sh, ch, j)
  • Lower facial muscle tone
  • Sleep apnea
  • Altered levels of oxygen and carbon dioxide
  • Temporomandibular joint disorder (TMJD)

Importance of breathing through the nose

First of all, you need to find out why your child is breathing through their mouth. Is it habitual or do they have an obstruction to their upper respiratory pathways causing the mouth breathing? For this, you need to consult with an ENT or ORL (Ear Nose Throat doctor also known as an Otorhinolaryngologist).

It is important to remediate this way of breathing because of all the harmful effects. By breathing through the mouth, the individual does not receive the benefits of the nose’s filtering system. The nose is a natural filter, it provides a filtering system for airborne polluted articles. The mucous and hair in the nose traps those particles to prevent them from entering the lungs and thus can decrease the chance of allergies, asthma, periodontal diseases and more. The nose also humidifies the dry air and warms it up before it goes into the lungs whereas mouth breathing dries up the tissues of the mouth.

Importance of a proper mouth resting posture

Given all the effects listed previously, it is hard to dispute the importance of a closed mouth resting posture. Once again you must first find out why your child has an open mouth resting posture – weak muscles, breathing difficulties, habit, tongue protrusion, etc.

Once you have ruled out upper airway restrictions you can consult a speech-language pathologist for an assessment to look at oral motor anatomy and function, swallowing and speech. They can then guide you and counsel you on appropriate exercises and strategies to correct your child’s resting posture.

Prevention is key. If you notice early on that your child adopts this mouth position on a regular basis then start working on it. The longer you wait the harder the change will be and some effects may be irreversible. Orthodontic work is very expensive and you can potentially avoid it with simple exercises at a young age. You would also want to make sure that whatever orthodontic work is done is going to last because if your child continues to use an open mouth then your child would have went through a big ordeal for no reason as the teeth will shift. Consult with specialists before spending your money and time to make sure that it will be worth it.


Pacifier use can be a personal parental choice. Some parents choose to introduce them and others do not. Many tend to focus on the negative effects of pacifier use but there are actually some benefits as well. The negative effects come into play past a certain age, usually around the age of 2 years old. I personally believe that as soon as a child is speaking then the pacifier should go. I have seen toddlers 2-3 years old speaking with pacifiers in their mouths throughout the day and that is not appropriate. I understand that it can be difficult to wean children off of pacifiers and we will discuss that in another post. Today I simply want to share some information about the positive and negative effects of pacifier use.

Effects of pacifier use

Positive effects

  • Analgesia (pain relief)
  • Shorter hospital stays for preterm infants
  • Reduced risk of sudden infant death syndrome
  • Reduced anxiety

Negative effects

  • Early breast weaning or breast feeding difficulties
  • Dental changes (malocclusions)
  • Infection
  • Otitis Media (ear infections)

Recommendations from doctors

Information regarding the effects of pacifiers was taken from studies conducted by the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP).

According to their studies, pacifiers provide a calming effect and are used for pain and anxiety prevention during minor procedures and hospital visits. They are also associated with shorter hospital stays for preterm babies and can improve their bottle feeding.  Pacifier use is also recommended during sleep to reduce the risk of sudden infant death syndrome (SIDS).

The AAP and AAFP suggest to introduce pacifiers to the baby once breastfeeding is well established to prevent difficulties past one month of age. It is recommended to stop using pacifiers by the age of 2 years old. Children who continue sucking on pacifiers past 2 years old have a higher incidence of malocclusion/dental issues. Children using pacifiers past 6 months of age may also have increased risk of recurrent otitis media (ear infections) – the sucking patterns can lead to reflux of nasopharyngeal secretions into the middle ear and eustachian tube dysfunction.

Thumb sucking

Some children will suck their thumbs as a substitute for their pacifiers. Other children will have been sucking their thumb in utero before they were even born and have a long lasting habit. Babies are born with the natural reflex to suck on something. This urge or reflex starts to decrease after 6 months of age. By 3 years old, children should naturally wean themselves off of thumb sucking. The advantage of thumb sucking is that the child has found a way to self-soothe and find some calm. However, past a certain age the negative impacts of thumb sucking start to outweigh the single benefit.

Effects of thumb sucking

  • Dental malocclusions (over bite and open bite)
  • Skin problems on the thumb
  • Speech (improper articulation of sounds t, d, n, l, s, z, sh, ch, and j)
  • Social issues (ridicule, inappropriate the older you are)

Main Effects

These common oral habits seem to have two main common effects after a certain period of time – dental issues and speech impediments. They affect primarily teeth alignment and the way the teeth close together. They also impact the way the tongue should be during it’s natural resting posture leading to speech impediments. The speech impediment most commonly seen is that of a lisp (when the tongue sticks between the teeth or pushes against the teeth). Thus your child may say “thoup” for “soup” when speaking.

These effects may seem primarily aesthetic in nature but in the long run they can impact your child’s self confidence if they are being ridiculed for the way they speak or look.

Luckily, most effects can be prevented early on by weaning children off of habits they should no longer be using and by using an appropriate mouth resting posture. Stay tuned for a post regarding strategies to help you tackle these oral habits!

open bite

over bite

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