Step 1: Understand Frenkel defect.
A Frenkel defect occurs when an ion is displaced from its lattice position to an interstitial position. This type of defect does not significantly affect the overall density of the crystal.
Step 2: Conclusion.
Frenkel defect does not change the overall density of the ionic solid.
Final Answer:
\[
\boxed{\text{Does not change}}
\]