A hashtag is a #word type that helps Twitter users to organize information and follow certain subjects. If you are posting an update on your practice, you might want to follow a pattern that will help those searching for dental services find your tweet. An example: "#dentist #implant #atlanta #cosmetic: link to your blog post". Your status will be seen by your followers but also to those Twitter users that interested by the four hashtags you included: dentist, implant, atlanta, and cosmetic.
Make sure you thank your followings/friends for "re-tweeting," or sharing your post with their followers and friends! Click to read more about Twitter and social marketing.