When the plaque on your teeth is not cleaned, periodontal disease can occur. Adults can lose their teeth due to plaque buildup, but this is only one of the reasons that may cause bite problems or loose teeth in adults. Bruxism, or tooth grinding, can cause these dental issues as well, due to too much biting force being applied to the teeth, causing loosened teeth or changes in the bite.
Loose permanent teeth need to be immediately addressed. Talk to your dentist, as it may indicate other concerns, such as a tooth infection.