Overview 

Teething (eruption) is directly related to jaw development. Teething is the process in which teeth emerge from beneath the alveolar bone, pass through the gum line (oral mucosa) and into the mouth (oral cavity). Jaw development is directly related to the overall health of the patient.¹ Jaw development initially occurs in the mother’s womb (in utero) when the teeth form, followed by teething, later, the primary (milk) teeth are shed and replaced by the growth of permanent teeth. Eruption of teeth during our growth phase causes the jaw development; some other factors, like genetic, environmental and masticatory forces, also play a vital role. An underdeveloped jaw can result in various health issues like crooked teeth and narrow nasal passages, which can subsequently cause a change in the posture of the jaw and affect facial development.²

Teething process and primary dentition

It usually marks an important landmark in the child's overall development, as it helps in mastication (chewing), establishing oral motor behaviour and proper posture of the jaws.³ Teething occurs in an order ( chronological order), and it usually varies from individual and is usually based on genetics, hormonal influence, diseases, and the overall health of the individual. There are 20 milk teeth ( deciduous teeth). It can erupt as early as 4-8 months and can last up to 30-36 months( Figure 1 and table 1 ⁴ After 6 months, the mother’s protective antibodies ( passive immunity) start to wean off, and the child is exposed to various pathogens which can cause a wide variety of symptoms.⁵

Figure 1 shows the various teeth in the primary dentition

Table 1 shows the mean age of teething of upper and lower teeth.

Usually, an 8-day window period is a common finding of the physiologic symptoms related to teething. 4 days prior, the day of eruption and 3 days after teething. The symptoms are usually very mild, like:

• Increased biting, gum rubbing, sucking 
• Increased Irritability
• Increased drooling of saliva 
• Frequent rubbing of the ears
• Facial rash, especially around the mouth
• Swollen gums
• Loss of appetite for solid food
• Difficulty in falling asleep and night crying.
• Mild temperature elevation

Teething is not associated with

• High fever of more than 101 F
• Rashes all over the body
• Diarrhoea, cough and cold 
• Prolonged fussiness

These should be considered alarming and should be consulted with physicians, as they can be the signs and symptoms of some other serious illness.⁶

Jaw development during teething

Eruption pressure 

The teeth develop from below the bone, and this process causes frequent bone removal and deposition (remodelling). This plays an important role in jaw formation.⁷

Chewing 

As the babies start biting on objects, it would lead to the strengthening of the masticatory, and this in turn affects the jaw growth, and it will help in shaping the jawbone.⁷

Permanent teeth development

The milk teeth are usually small and 20 in number, and when the new teeth (permanent teeth) come out, they actually come in an order. This allows the space to be maintained, and this prevents crowding of teeth. There are many adaptation features for space maintenance in primary teeth, like leeway space, primate space and also wide spacing between teeth.⁷

Dental arch

It is the U-shaped arch on which the teeth come out, and the tooth bud formation occurs in the womb, and each tooth has a specific time for formation. This arch is associated with the underlying alveolar bone, which plays a key role in influencing jaw development. So if any tooth or a number of teeth are missing, then it can affect the alveolar bone development.⁷

Genetics

Genetics usually plays an important role in jaw development; for example, if a child inherits a small jaw from one of the parents and big teeth from the other parent, it may lead to crowding of teeth. If it occurs the other way around, it can cause spacing. Genetics plays a direct role in both jaw development and the teething process.⁷

 Diseases 

There can be many genetic or other diseases that affect teething and jaw development.

When there is increased growth hormone, it can lead to gigantism, which can cause increased growth of jawbone. Acromegaly is a condition that occurs in adults due to excessive production of growth hormone. Other diseases like Paget's disease can cause enlargement of the jaw bones. There are many diseases that cause the absence of teeth and can affect jaw growth, like Ectodermal dysplasia.^.7

Teething-related habits and their effects 

There are many habits that can cause problems for the teeth

Thumb sucking 

 It is actually done by all the kids and it is normal. When the child grows up, and after teething, if this habit is continued, then it can lead to spacing between the teeth, and the teeth will move forward

Swallowing pattern

 Usually, we swallow food by placing the tongue behind the upper teeth. There is an infantile swallow pattern which later gets lost after the eruption of teeth, but in some children it persists and is retained. They thrust the tongue between the teeth and also strain the lip and chin muscles. This process exerts pressure on the teeth this causing spacing, and the teeth move forward.

Tongue tie

 If there is severe tongue tie, then the child will have difficulty in moving the tongue forward, speaking, and even swallowing food.

Underdeveloped jaw and its effects 

Mouth breathing 

There are many reasons for mouth breathing, like adenoids, allergies that cause frequent colds and coughs, and a deviated nasal septum. It can be due to an underdeveloped maxilla (the upper jaw), which can cause reduced air flow and lead to mouth breathing. These can cause forward movement of teeth, enlarged gingiva, and cavities in the teeth, and they can also result in a long face (adenoid facies).^8,9

Soft food and chewing 

Our ancestors used to eat raw food, and this caused the strengthening of the masticatory muscles. Nowadays, we eat only cooked and processed food that is soft. This is also a reason for crowding. Most people do not have wisdom teeth because of reduced space in the jaw.^8,9

Underdeveloped jaw

 As a result of a small jaw, there is a chance for crowding. So these misaligned teeth can cause TMJ pain and difficulty in chewing.^8,9

Sleep issues

A small mandible or an underdeveloped maxilla can cause sleep apnea can cause disturbances in sleep.^8,9 

Temporomandibular joint problems

 There are many reasons for TMJ problems. Ankylosed TMJ would cause difficulty in opening the mouth, and this would affect the tooth eruption.^8,9

Clinical perspective and recommendations

Myofunctional therapy

 It is usually helpful in correcting mouth breathing, tongue thrusting, and it helps to improve muscle strength, tongue posture.¹⁰

Breathing exercise 

Breathing through the nose and proper tongue posture helps in proper alignment of teeth and can prevent crowding to some extent.¹⁰ 

Tongue tie surgery 

Frenectomy and frenuloplasty can reduce the misalignment caused due to tongue tie.¹⁰

Orthodontic intervention

There are fixed as well as removable appliances. In some cases, only the tooth is proclined, but there can be bony proclination; both can be corrected easily. Early intervention is needed as it is possible to change the bone growth, for example, mouth breathing can cause downward growth of the lower jaw (vertical growth), and these can also be corrected during the growing stage.¹⁰

Habit-breaking exercise for kids

Tongue thrusting, finger sucking and mouth breathing should be stopped at much younger age. There are many removable appliances available, like blue grass appliances. So these corrective appliances should be introduced at a much younger age so that they would help to enhance dental as well as physical health.¹⁰

Summary 

It is obvious that teething and jaw development are interrelated. If a tooth is missing, the alveolar bone in relation to the tooth is underdeveloped. The development of the maxilla and mandible is very important for the overall health of the patient, If the maxilla is underdeveloped, it leads to difficulty in breathing. So it is very important to take an early intervention. There are simple home remedies to complicated orthodontic treatments available. There are many genetic, hereditary or even developmental disorders that affect the teeth as well as jaws, so the treatment should be incorporated at the earliest for a better well-being of dental as well as overall health.