It is actually due to improper oral hygiene maintenance ,as we as a patient are not aware about the proper and effective tooth brushing technqiue.So you should consult a Dentist to get assistance and get your oral prophylaxis done once, later on you can maintain with toothbrushing and mouthwash rinses.
Next Steps
do visit your nearest Dentist, dental neglegance can lead to further more dental issues.
Health Tips
brush twice and do plain water rinses after your every meal.