The teeth depend on bone and gums to stay in position. So if there is an imbalance of the supporting structure the teeth will eventually fall off. As a matter of fact, most periodontal diseases are preventable with proper oral hygiene, and since pain is not a regular symptom, most people neglect and postpone their dental visits for too long.
Never neglect gum diseases: Speaking of adults, tooth loss is mostly caused by poor periodontal (gum) health. This periodontal disease is caused due to prolonged tartar (hard buildup) and plaque (soft buildup) buildup on teeth that leads to irritation and bleeding gums that further lead to bone loss, irritation, and loss of teeth.
Solution: Routine Oral Examinations (every 6 months or lesser), dental prophylaxis, and scaling as needed are known to prevent Periodontal disease