There are several types, or degrees, of impaction based on the actual depth of the teeth within the jaw:
Soft Tissue Impaction: The upper portion of the tooth (the crown) has penetrated through the bone, but the gingiva (gum) is covering part or all of the tooth’s crown and has not positioned properly around the tooth. Because it is difficult to keep the area clean, food can become trapped below the gum and cause an infection and/or tooth decay, resulting in pain and swelling.
Partial Bony Impaction: The tooth has partially erupted, but a portion of the crown remains submerged below the gum and surrounding jawbone. Again, because it is difficult to keep the area clean, infection will commonly occur.
Complete Bony Impaction: The tooth is completely encased by jawbone. This will require more complex removal techniques.