Captek may be largely marketing hype.  If you do a literature search
for Captek on pubmed.org, you find 14 articles, about half of which are
in trade journals.  Captek is a functional type of PFM, but with the
gold only like 0.3 mm. thick in captek, it is presumably not as strong
as a regular PFM restoration.  Captek is meant mostly to be of esthetic
value, supposedly by combining thin gold with porcelain to achieve a
nice esthetic effect.  Some controversy about whether they are strong
enough for posterior teeth, although some dentists place them there.
They look good for anterior teeth, although the jury is out if this is
any better than white gold PFMs or yellow gold PFMs.  I put a captek
once and noticed a blue line at the gingiva after a few weeks.  What
causes this "blue line" in the gingival margin?  Do a pubmed search and
it is hard to get a definitive answer.  It is said to go away by
putting peroxide subgingivally to break up the stain molecules.

Two trumpeted advantages: esthetics (controversial) and supposedly
according to one or two articles, there is little bacteria growing
around their margins.  But who cares about bacteria?  Bottom line: any
crown margin will get caries if patient doesn't have good oral hygeine,
and any crown will not get decay for decades if oral hygeine is good.
Also, there are many factors besides mere presence of bacteria around a
crown margin that determine if the crown will get marginal decay or
not.  Mere presence of bacteria is by itself not very significant.

Better to go for strength, with full standardized metal coping
thickness.  The esthetics of a standard PFM, even white gold in
anteriors, can be quite perfect.  It depends on where the margin is
placed and how artistic is the laboratory worker.  With lab work you
get what you pay for.  Cheap work and cheap sh.t go hand in hand.  The
"blue line" effect may have nothing to do with the metal in the coping.

The best restoration is pure gold for crowns, if the crowns can take
the occlusal load where they are placed.  Why?  Pure gold burnishes
with each tooth brushing, sealing and resealing the margins and
preventing decay.  White gold is too hard to self-burnish, although it
withstands occlusal loads better.  Pure gold may have esthetic
concerns, but then again pure gold with pink gingiva makes a nice color
combination.  Matte finish the gold and it won't reflect light when the
patient opens his/her mouth.

I have been reading on the internet regarding Captek and full cast gold
copings.

Full cast gold copings oxidize upon firing - Captek doesn't

However if polished isn't the appearence of Porcelain fused to High 90+% gold
similar and just as long lasting?

The captek process seems to take longer for the labs to produce than the
standard PFM.

Are the only advantage cost and bacteria resistant?

Is there an advantage of porcelain fused (or pressed) to captek vs full cast
gold?

Where can I find the research behind the claim that captek is bacteria
resistant?