Depending on where you live you might be able to find a free dental clinic to go to for dental care
. Another option is to find a dental school near your area to become a patient. They have discounted rates, you have high quality work completed by training dentists heavily supervised by seasoned dentists in their clinics. The downside is that the work takes longer to do and your appointments may be anywhere from 1 1/2 hours to 3 hours long.
Black material in the cracks of your teeth can be staining from years of neglect, arrested caries (areas that had active cavities that stopped and now have remineralized), they could be active areas of decay or just part of the natural anatomy of your teeth.
Itchy and/or numb teeth could be due to the inflammation of your gums and require a dentist intervention and evaluation.
These issues can only be addressed by actively seeking a dentist in your area and being evaluated for proper diagnosis.
Sometimes when teeth are extracted small parts of bone break and may not be taken out at the original time of the appointment. This bone can either reattach or will be rejected by the body and come out through the gums. This is a common but possibly painful experience.
Abscesses are extremely important to be seen by a clinician. They can lead to infections of the sinus
that can lead to an infection in the brain and even death if neglected.
I hope this information helps. Best wishes for well health.