A properly positioned modified Water's is determined by which of the following criteria?
the petrous pyramids fill the lower one-third of the orbits
the petrous pyramids fill the maxillary sinuses
the petrous pyramids half fill the maxillary sinuses
the petrous pyramids lie inferior to the maxillary sinuses
the petrous pyramids half fill the maxillary sinuses
Rationale: The modified Water's aligns the LML perpendicular to the IR. Since the chin is not positioned as high, the petrous pyramids will fill half the maxillary sinuses instead of falling below the maxillary sinuses.
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