In primary dentition, a mesial step is associated with permanent molar relationship Class III.

In primary dentition, a mesial step is associated with permanent molar relationship Class III.

• A. Class I
• B. Class II
• C. Class III
• D. None

Answer: (C)

The main idea is predicting how the back teeth will line up in the permanent dentition based on how they sit in the primary dentition. A mesial step means the lower primary molars sit ahead of the upper ones. This forward position of the mandible tends to carry into the eruption of the first permanent molars, so the lower molar ends up in front of the upper molar. That results in a Class III permanent molar relationship, where the mandible is relatively forward compared to the maxilla. In contrast, a flush terminal plane can drift toward Class I with growth, and a distal step tends to produce Class II. So, a mesial step is best associated with Class III.

The main idea is predicting how the back teeth will line up in the permanent dentition based on how they sit in the primary dentition. A mesial step means the lower primary molars sit ahead of the upper ones. This forward position of the mandible tends to carry into the eruption of the first permanent molars, so the lower molar ends up in front of the upper molar. That results in a Class III permanent molar relationship, where the mandible is relatively forward compared to the maxilla. In contrast, a flush terminal plane can drift toward Class I with growth, and a distal step tends to produce Class II. So, a mesial step is best associated with Class III.