MO cavity

MO cav·i·ty

(kavi-tē)
The presence of a carious lesion involving the mesial (M) and occlusal (O) surfaces of a tooth.

MO cavity,

n a cavity on the mesial and occlusal surfaces of a tooth. See also DO cavity, Class 2.
References in periodicals archive ?
For example, in Scenario Two, where a 5-year-old patient presents with a MO cavity in tooth 85 with loss of the marginal ridge and who is not dentally anxious.
In this study, the MO cavity preparation was prepared in second molars and the DO cavity preparation in first molars because carious lesions usually follow this pattern clinically.