What happened

Shares of Align Technology Inc. (ALGN 0.19%), the company behind Invisalign clear dental aligners, fell 43.5% in October, according to data from S&P Global Market Intelligence. Hints of a slowdown in the company's third-quarter earnings report have investors frightened. 

So what 

Important patents that made Align Technology a top-performing stock in recent years began expiring last year. When signs of a slowdown that the company warned investors about a few months ago turned out to be a bit worse than expected, investors reacted harshly.

Tired looking person holding a downward sloping arrow.

Image source: Getty Images.

Clear-aligner revenue rose 25% versus the prior-year period, but fell 1.4% when compared with the previous quarter. On the bottom line, net profits rose 22% year over year but fell 4.9% versus the previous quarter.

Now what

Align is still the leading manufacturer of clear aligners and recently bought a large equity stake in one of its leading competitors. As part of the deal, the Smile Direct Club now buys its clear aligners exclusively from Align Technology.

Smile Direct Club offers simpler solutions that people can use from their own homes, a segment that has a lot of room to grow. Misaligned teeth are a problem for around two-thirds of the world's population, but relatively few will ever step foot into an orthodontist's office. 

Do-it-yourself kits offer slim profit margins compared with aligners that people receive at their dentist's office. With a leading share of both the professional and consumer markets, though, Align has a growth story that probably isn't finished yet.