The most commonly used shadeguides are very consistant.  That doesn't
mean it is easy to duplicate the shade in a real-life situation.
    B2 is a fairly light shade in the gray range.  You are less likely to
get a really noticeable change from B2 than you are to get if you are a
dark yellow A4.  The white speck is probably an area of focal
hypocalcification (an imperfection in the enamel) and this is very
unlikely to disappear with any kind of bleaching.

Steve

I have my shade guide arranged according to "value".  The higher the value,
the brighter/whiter the tooth.  B2 is the third "whitest" shade (out of 16
shades) on the Vita shade guide.  Only B1 and A1 have a higher value
(ie--whiter). There are shade guides out now, however, that have teeth up to
5 or 6 shades whiter than B2.  These guides were made to keep up with the
demand for artificially bright white veneers and bleached teeth.

My experience with teeth that have a white "spec" (known as a
hypocalcification) in the front is that the rest of the tooth typically
bleaches very well and "catches up" with the hypocalcified area.  After 2
weeks of bleaching, the spec is almost completely invisible relative to the
rest of the tooth.

When you first start bleaching, the white spec will appear even whiter and
more noticeable than it does now.  Don't panic.  The rest of the tooth will
usually catch up as you proceed with the bleaching.