Tooth mobility should be determined using two single-ended instruments (e.g., mouth mirror and probe). Fixed reference point should be selected (e.g., adjacent tooth that is not mobile) and pressure should be applied in horizontal buccal-oral direction to the tooth we are testing.
Grade 0 mobility = Normal (physiologic) tooth mobility
Grade 1 mobility = Detectable mobility (up to 1mm horizontally)
Grade 2 mobility = Detectable mobility (more than 1 mm horizontally)
Grade 3 mobility = Besides detectable mobility in horizontal direction, detectable significant vertical mobility