CNA – If you notice a gap or two in your child’s front teeth, you might wonder if they’ll close as your child grows. The answer depends on their age and whether they have finished replacing their milk teeth with permanent ones.
Typically, a child’s 20 milk teeth begin to emerge around six months old, though this can vary. By about six years old, these milk teeth start to fall out, making way for the 32 permanent teeth that will gradually take their place.
But sometimes, those numbers just don’t happen because of hypodontia.
“Hypodontia is the congenital or developmental absence of one or more baby or adult teeth,” said Dr Low Yuxuan, an associate consultant with National Dental Centre Singapore’s (NDCS) Department of Orthodontics.
In other words, your child could be born with one or a few teeth that are completely missing – up to six in some hypodontia cases – and not that they have failed to emerge.
HOW COMMON IS HYPODONTIA?
More than one in 10 patients (about 11 per cent) who require braces at NDCS have hypodontia, said Dr Low, citing two studies that span 2017 to 2019.
The condition often affects permanent teeth, according to associate consultant Dr Judith Quek with NDCS’s Paediatric Dentistry department, although it can also be seen in milk teeth. “If the milk tooth is missing, there is a higher chance of the adult tooth being missing, too,” she said.
Dr Sharon Leng, Tooth Stories’ dental surgeon, who used to provide dental services in schools, has also noticed that hypodontia affects adult teeth more than milk ones. “About one in 10 adolescents I have seen had hypodontia in their set of adult teeth, while one in 15 children had hypodontia in their set of milk teeth,” she said.
WHAT COUNTS AS HYPODONTIA AND AT WHAT AGE IS IT SEEN?
There may be reason to suspect hypodontia if the milk and permanent teeth don’t emerge in a timely manner. It definitely counts as hypodontia when a milk tooth is still intact – but the permanent tooth is not present on X-rays or other investigations, said Dr Leng.
Here’s a typical timeline from Dr James Ho, the founder of GPlus Dental Center and G Dental Center, to help you track your child’s dental developments:
- Early childhood (ages three to six): The milk teeth should have fully emerged. Keep an eye on any missing ones.
- Mixed dentition phase (ages six to 12): Monitor the shedding of the milk teeth and the eruption of permanent ones. Delays or gaps during this process may not necessarily indicate hypodontia but should prompt a visit to the dentist for evaluation.
- Late childhood to early teens (ages 10 to 14): Most of the permanent teeth, except for wisdom teeth, should have erupted. The absence of expected teeth should be evaluated by a dentist.
“We often recommend a full mouth X-ray to be taken at eight years old when the child has both milk teeth and adult teeth,” said dental surgeon Dr Jeremy Peter from Tooth Stories. “At this stage, any adult teeth that are to form are likely to be visible on the X-ray, and any teeth missing also become more evident”.
WHICH TEETH ARE OFTEN MISSING IN HYPODONTIA?
“The three most common missing teeth are – in decreasing order of frequency – the upper lateral incisors, the lower second premolars and the lower incisors,” said Dr Peter.
Wisdom teeth or third molars are not included when defining hypodontia, said Dr Ho, “because their development varies widely among individuals”. “It is common for one to four wisdom teeth to be absent in up to one-third of the population, making their absence less clinically significant,” he said.
WHY DOES HYPODONTIA OCCUR?
There is often a strong genetic component, said Dr Ho, highlighting specific genes, such as MSX1, PAX9 and AXIN2. “Mutations in these genes can lead to the developmental absence of teeth,” he said.
The condition is also associated with many syndromic conditions such as Down syndrome, Ehlers-Danlos syndrome and Ellis-Van Creveld syndrome, said Dr Low. These syndromes typically present with a cleft lip and/or palate, and it is common for these patients to be missing teeth near the cleft, she said.
Genetic mutations and syndromes aside, external factors can induce hypodontia as well. “The dental lamina, a band of epithelial tissue from which teeth develop, is extremely sensitive to external stimuli and damage”, said Dr Quek. “Disturbances arising from trauma, infection, radiation or chemotherapy have been associated with missing teeth.”
This might also explain why the adult or permanent teeth are more commonly involved in hypodontia. “They are subject to a longer period of potential genetic and environmental influences”, said Dr Ho. “Milk have a shorter window for developmental disruptions, making them less susceptible to such issues.”
At times, “the improper shedding of the milk teeth (that is, they fail to fall out naturally), can impact the development and eruption of the permanent teeth”, said Dr Ho.
ARE MISSING TEETH A CONCERN?
Aesthetics and self-esteem issues aside, having “insufficient upper and lower teeth in contact” can cause chewing problems and dental health issues such as “food impaction due to tipped or drifted teeth”, said Dr Low.
“Take high-fibre foods such as leafy vegetables and fruits as examples,” said Dr Peter. “If you cannot chew them, you would not be able to consume or digest them well.” There are also “difficulties in speaking and the further misalignment of the remaining teeth” to consider, he added.
WHAT DENTAL SOLUTIONS ARE AVAILABLE?
Depending on the number of missing teeth and their locations, it may not always be necessary to replace them, said Dr Quek, especially when the child still has his milk teeth. To replace multiple missing adult teeth, dentures or bridges may be used to improve function and aesthetics, she said.
“Orthodontic treatment or braces may be indicated to redistribute the spaces between teeth to optimise the position of replacement teeth,” said Dr Low.
Dental implants, on the other hand, may be extreme for children and are not recommended because their jawbones are still growing, said Dr Peter. “My professional preference for a minimum age to receive dental implants is 24 years old.”
Sometimes, the wisdom teeth may be used to help close the gaps, said Dr Leng, if X-rays do indeed show that at least one adult tooth is absent.
To help you make informed decisions for your child, here’s a guide from Dr Ho:
Early childhood (ages three to six): Braces and implants are generally not recommended as the child’s jaw and teeth are still developing.
Mixed dentition phase (ages six to 12): Braces, Invisalign or other orthodontic appliances may be used to manage spacing issues and guide the proper alignment of the adult teeth. Dental implants are typically deferred until after jaw growth is complete.
Late childhood to early teens (ages 10 to 14): Braces or other orthodontic treatments can correct alignment and spacing issues, and prepare the mouth for potential future dental implants.
Adults (ages 18 and above): Your child may still benefit from braces or Invisalign to address alignment issues. Implants, at this stage, are a common solution, provided the jawbone is healthy and fully developed. Fixed bridges, removable partial dentures or complete dentures may also be considered based on the extent of tooth loss and patient preference.
