In the past, it was important to target misspellings of words because search engines such as Google and Bing! did not always auto correct. So if someone was looking for "implant dentest" instead of "implant dentist",a web page with the misspelling may appear high up in search engine listings.
Note, however, that purposely misspelling text for the goal of grabbing results from these misspellings is a big mistake. Search engines are "smart" and they will not only automatically correct misspellings, but they will give results based on what the search engine thinks the user was looking for.
In the example below I typed in "Implant Dentest" and look what Google did for me: