Which terminal plane relationship is characterized by no net mesial or distal inclination of the molars?

The terminal plane relationship characterized by no net mesial or distal inclination of the molars is known as the flush terminal plane. In this relationship, the maxillary and mandibular first molar cusps align directly with one another when viewed from the side; that is, the maxillary molar is situated flush with the mandibular molar.

This situation typically occurs when the first molars are in a neutral position, allowing both to interdigitate without favoring either direction (mesial or distal). As a result, this alignment can be a starting point for evaluating the occlusion and making future orthodontic treatment decisions.

Understanding the flush terminal plane is crucial because it can influence how the teeth develop and align during growth. It serves as an important reference point in orthodontic assessments and treatment planning.