In a patient with pemphigus vulgaris, which dental instrument/procedure should NOT be used during oral hygiene care?

In patients with pemphigus vulgaris, the positive Nikolsky sign indicates that even minor friction or trauma can cause new blister formation and mucosal separation. Abrasive air polishing (prophy jet) uses pressurized sodium bicarbonate or aluminum oxide particles that can traumatize the fragile mucosa and trigger new lesions. Mouth mirrors, if used gently, are safe. Ultrasonic scalers should also be used with caution (gentle technique), and soft-bristled toothbrushes are recommended for home care.