It's doubtful. None of the standard Medigap plans available in most of the states offer dental care as a covered service. Federal law does permit the states to allow Medigap insurers to add new benefits to the standardized plans, so it's possible your Medigap policy might now cover dental care. To find out for sure, read your policy or ask your insurer.
Other options for dental care might still be available to you even if your Medigap policy doesn't cover it. Are you or your spouse still working? If so, you might be able to get group dental coverage through one of your employers. In addition, dental insurance is often offered to members of group associations or organizations, and some group health plans may include limited dental coverage (e.g., coverage for reconstructive dental work due to an accidental injury). Finally, consider purchasing private dental insurance, particularly if you know you'll be needing some costly dental work in the future. Unfortunately, though, private dental insurance can be difficult to find.