Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Teeth-straightening specialist Align Technology (Nasdaq: ALGN) saw its shares plunge as low as 15% in early trading today, after issuing a disappointing fourth-quarter outlook.

So what: Align managed to top analyst expectations for the third quarter, but a softening dental market doesn't bode well for next quarter's results. Align's North American dentists are continuing to report lower visits and weak demand for expensive procedures, explaining the lower-than-expected submissions for its Invisalign system, as well.

Now what: While Align's unique invisible braces have had some success over the past few years, I'd urge Fools not to pounce on today's price plunge. A less than ideal operating environment, coupled with increasing bracket-free competition from the likes of Orthocare, DENTSPLY (Nasdaq: XRAY), and even 3M (NYSE: MMM), makes the stock's still lofty price ratios just too risky for my tastes. Of course, with a current stranglehold on the market, Align is at least worth following.

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