First of all, that string of consonants means that your dentist graduated from an accredited dental school. This means that your dentist is trained and certified as a dentist. They have the proper training to treat you. If you ever run into a dentist who lacks these letters, then you want to think twice before scheduling an appointment.
DDS means, Doctor of Dental Surgery, and DMD means, Doctor of Medicine in Dentistry or Doctor of Dental Medicine. Whether your dentist has a DDS or DMD, it means that they are have the same education and have met the same requirements but that they simply have a different title.
To become a dentist, you must have completed an applicable undergraduate degree, and then must attend four years of dental to become a general dentist. A lot goes into your dentist’s training, so you can trust them to know what’s best for your oral health.