The fact is that Oral-B just lost a client.
If you are wondering why, just look at the difference among Oral-B and Conad dental floss product design in the following image.

What’s wrong with the Oral-B dental floss product design

So, what’s wrong with the left hand side product design?
Quite intuitive… It simply doesn’t let the consumer understand when the floss is going to finish.

Despite leader in this market, Oral-B forgot to put the user at the center of its product design.
Consequence of this, is an injection of frustration each time the user recognize the dental floss is ended and, as a result, in customers’ minds the only culprit is identified with the Brand, that doesn’t provide users any chance of control over the product’s consumption.
And that’s no good.

Now. Suppose you use the right one with its transparent plastic wrapper. If the dental floss finishes while it’s in your hands who’s in charge of this? 
Definitely not a wrong product design!
(nor the producer, course…)

Basically, that’s the reason why I just abandoned Oral-B in favor of the Conad dental floss (even if quality is lower!)

Hope this basic example can pass to you the importance of the UCD (user centered design) and the possible downsides for brands not enough careful.