Which primary molar relationship is predictive of a Class II permanent first molar relationship?

Which primary molar relationship is predictive of a Class II permanent first molar relationship?

• A. In flush terminal plane
• B. Distal step
• C. Mesial step up to 2 mm
• D. Mesial step more than 2 mm

Answer: (B)

Distal step in the primary molar relationship is predictive of a Class II permanent first molar relationship. When the lower molars sit further back than the upper molars in the deciduous dentition, this posterior relationship tends to persist as the permanent first molars erupt, resulting in Class II molar alignment. In contrast, a flush terminal plane is a neutral position that commonly shifts to Class I with normal jaw growth, and a mesial step tends to lead to Class I or Class III depending on future growth, not Class II.

Distal step in the primary molar relationship is predictive of a Class II permanent first molar relationship. When the lower molars sit further back than the upper molars in the deciduous dentition, this posterior relationship tends to persist as the permanent first molars erupt, resulting in Class II molar alignment. In contrast, a flush terminal plane is a neutral position that commonly shifts to Class I with normal jaw growth, and a mesial step tends to lead to Class I or Class III depending on future growth, not Class II.