There are thousands upon thousands of images available on the Internet that you can use on your dental or medical website in your pages and in your posts. However, you must make sure that the images that you select, are legal for you to use.
Now I'm not a lawyer so I'm not giving legal advice here -- I'm simply stating what I think are the best (and safest) practices for you to follow when you pick images for your blog or website.
1. Just because you can right-click and save the image, or copy and paste the image, doesn't mean the image is free.
2. The statement, "I didn't see a copyright or a restriction notice on the image so I used it." won't hold up. There is an assumption under U.S. Copyright law that once something is published, then copyright is assumed, even if the item in question hasn't been officially registered with the Copyright Office, and even if there's no "copyright 2013" information visible.
3. Make sure that your web developer is using LEGAL stock images (when stock images are used -- using your own images are almost always a better choice). The best way to do this is to select images together from a reputable royalty-free image site such as istockphoto.com. For my clients I purchase the images for the client and then give the client the image at the end of the project (retaining a proof-of-purchase of course) and if I use the image again for another dentist, 5,000 miles away, we purchase the image again.
4. There is no such thing as "borrowing" an image or giving "attribution". Just because you used an image without permission, but gave the owner credit, does not absolve you from copyright violation. The best, and safest way to secure stock images for your website is to purchase the images from a reputable image vendor, where you can prove -- in writing -- that you purchased a license to use the image.
5. Read the license. I know this sounds crazy, but at least briefly take a look. Many image houses will have restrictions on what you can do with an image based on the license. For example, in a basic license scenario, you are allowed to use the image as many times as you'd like on your website, but you cannot use it commercially to make and resell coffee mugs or t-shirts. Usually the latter uses are clearly indications for an extended (or similar) license, but it's up to you to check it out.
Ultimately, what goes on on your website (as in your office), is your responsibility. So take the time to check-out your stock photos, and at least to make sure the developer is using properly licensed copies of the images for you.
Do you have any questions about stock photography?