aakk9999 - 7:20 pm on Jan 27, 2011 (gmt 0)
Whilst use of canonical tag is a solution for some of URLs listed by the OP, I am not sure that the canonical tag is a correct solution for all URLs given in the OP example.
Google advice (see links to google by bumpski and jakegotmail) both talk about either:
- one product being accessed via multiple URLs; OR
- a page with the same list of products being re-ordered by a different criteria.
Link to Google by jakegotmail, emphasis mine:
It's common for a site to have several pages listing the same set of products. For example, one page might display products sorted in alphabetical order, while other pages display the same products listed by price or by rating.
From the OP URLs, we can see that he has multiple pages of products, and that these can contain different set of products per page depending on the page number and/or sort criteria. This does not always result in the same list of product being on different URLs.
That is, the first listing page does not have same products as page 2 and may not have the same products as page=3&sort=3d.
So personally, I would not set all these pages to be a canonical of the first listing page (which is probably www.example.com/endodontics-c-8.html)
One of reasons why I would not do this is that I am not sure what happens with product links that are on the page 2 onwards if page 2 has canonical tag set to point to page 1 (e.g. I am not sure whether in such case Google just ignores the content from page 2, and whether this would result in products that are on page 2 not being indexed.)
Or in other words - having 10 pages of listing with 10 products each, and setting pages 2 - 10 to be canonical of page 1 - would this result in Google picking up only 10 products from my site and not crawling other 90?
With regards to URLs that are result of various sort criteria, then I think that canonical could be used to canonicalise page 1 with sort parameters to page 1, page 2 with sort parameters to page 2 etc.
I would appreciate if someone could correct me if my understanding of canonical behaviour/usage is incorrect, especially with regards to link discovery on pages that have canonical tag pointing to a different page.