I had a new patient in recently who has Down Syndrome. Swords Orthodontics is happy to help all sorts of patients, but we rarely see patients with this particular condition so I thought I’d better refresh my knowledge on Down Syndrome and what it means for a dentist or orthodontist treating someone who has it.
This blog might be more of interest to other dentists than the general public but if you know someone with Down Syndrome then it might be useful for you to read about the dental aspects.
As it turns out, there is a great recent article out of University College Cork by Sinéad Brosnan in Dental Update (Vol 48, Issue 11, 2021 p907-912). In orthodontics, I found a handy overview in Angle Orthodontist by David Musich (Vol 76, Issue 4, 2006 p734-735).
But first….is it Down Syndrome or Down’s Syndrome? Ireland and USA tend to say Down Syndrome. The UK prefers to use Down’s Syndrome. It was described by a guy called John Down about 150 years ago, and the argument on the apostrophe is to do with the fact he described the condition, but he didn't actually have it himself.
A few highlights....
It’s a relatively common for a chromosomal disorder, classically the variation known as Trisomy 21, but there are a few other varieties.
The prevalence quoted is 22 people in 10,000 for Europe, though I have seen figures quoted of 10 in 10,000 (worldwide) to 14 in 10,000 (USA). Down Syndrome Ireland’s website says it affects about 22 babies in every 10,000 born. Just to put that into context, I work on figures of 200 people in 10,000 having impacted canine teeth in the upper jaw, 400 people in 10,000 missing adult teeth because those teeth never formed, and about 14 people in 10,000 in Ireland born with a cleft palate.
It’s a condition that comes with a high incidence of medical problems, so it’s vital for a dentist to have a good medical history and confidence that the patient has had an appropriate schedule of medical examinations and investigations.
Medical problems more often encountered along with Down Syndrome –
- Cardiac defects particularly septal defects and Fallot’s Tetralogy - a dreaded question for dental students, which is usually followed in oral examinations with “you have said coarctation of the aorta, can you explain what that actually means?”
- Reduced immunity and increased susceptibility to infections, and an increased risk of leukaemia
- Muscle and joint disorders
- Sight and hearing problems
- Sleep apnoea
- Reflux disorders, coeliac disease
- Obesity
- Hypothyroidism
Dental problems that would be encountered more often –
- Class III malocclusion (lower teeth too far forward compared to the upper teeth) and class III skeletal pattern (lower jaw too far forward compared to the upper), hypoplastic maxilla (a small or under developed upper jaw), reduced nasal breathing
- High arched palate, large tongue, tonsil and adenoid problems, fissured tongue
- Hypodontia (reduced number of teeth), microdontia (unusually small teeth),
- Short roots (which can be an increased risk of tooth loss if the gums around them become unhealthy)
- Teeth slow to erupt
- Abnormalities in the enamel of the teeth
- Anterior Open Bite (the teeth at the front don’t contact as they should)
- Increased risk of gum disease
The orthodontic problems detailed in the Musich paper are very interesting.
At that time (2006), he noted there had only been 3 papers on the topic in the previous 25 years in the biggest two American orthodontic journals, but about 50 on cleft palate disorders. It's clearly a road less travelled.
- The class III tendency is present in over 50% of patients with Down Syndrome
- About 65% of them have posterior crossbites, related to transverse hypoplasia (the jaw doesn’t develop enough width-wise as well as front-to-back, so the top teeth bite inside the lower teeth instead of outside them)
- Developmentally missing teeth. He cites this is 20 times more frequent in Down Syndrome patients than the general population. The general population has about 4% frequency of missing teeth, so that means that most – not much less than all – Down Syndrome patients will be missing an adult tooth.
- Tooth Size Discrepancy more likely. This is a mismatch in the sizes of teeth in one jaw compared to the other. It’s particularly a problem in front teeth but usually only becomes obvious when the teeth are ideally positioned In Irish orthodontic patients in general, it’s usually cited as about 40% (O’Mahony et al, Angle Orthodontist, 2011 81(1) p130-133), about double the non-orthodontic population.
- Anterior Open Bite (as mentioned above)
- Tongue thrust and protrusive resting tongue posture. It’d be fair to say some orthodontists would implicate this in an anterior open bite problem, though there would still be disagreement if it’s cause or effect or coincidence
- Impacted teeth. I’d mentioned at the top that about 200 people in 10000 have impacted upper canine teeth, that’s about 2% of the general population. About 20% of Down Syndrome patients have this problem.
- Transposed teeth. This is where one tooth develops in the position of another. Unlike what I imagined reading about it in dental school, it’s rarely neat swap from one position to the other. When I started seeing enough patients to actually encounter it in the wild it usually has teeth overlapping or interfering with each other’s ideal positions. It took a while to get experience in this because it’s not that common – maybe 30 people in every 10,000 in the general population. You’ve probably guessed it by now but that number is going to be higher in Down Syndrome patients – about 50 times more frequent.
- Swollen gums. This can be a problem for putting braces on
- Chewing problems. It’s not clear if this is because the teeth don’t meet well or the patient has coordination problems.
In general, you can expect the orthodontic treatment to take place in multiple phases over an extended period of time. Think many episodes over several years, but my advice would be get assessed early so that there’s enough time to plan with a full range of options.
