Guinea pigs' teeth are "open rooted" and grow continuously. Sometimes the root grows or is pushed into the jaw, resulting in elongated roots. An examination of the mouth may give no clue that this condition exists.
Elongation of the lower roots can sometimes be felt as bumps along the jaw line.
Elongation of the upper roots may put pressure on the eye causing tearing, bulging of the eye, infection, or other problems.
For any guinea pig with suspected dental problems, an x-ray is an invaluable diagnostic aid. Some guinea pigs in the early stages of this condition can be maintained using a Chin Sling to encourage normal wear, after first properly planing the teeth.
The x-ray below of a guinea pig with elongated roots is contributed by Pinta.
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