8/19/2019 Molar Relationship the Anteroposterior Molar Relationship in Deciduous Dentition is Described in Terms of the Term…

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Molar Relationship

The anteroposterior molar relationship in deciduous dentition is described in terms of the terminal

planes. The terminal planes are the distal surfaces of the maxillary and mandibular second primary

molars. Moyers described three possible kinds of primary molar relationships (Figs 21.9A to C):

1. Straight/Flush terminal plane

2. Mesial step3. Distal step.

Flush Terminal Plane

In straight/flush terminal plane, the distal surfaces of the maxillary and mandibular deciduous molars

are in same vertical plane (Fig. 21.9A).

It is of significance to note that, the mandibular second primary molar has a greater mesiodistal

diameter than the maxillary 2nd molar. This difference in the dimensions makes the distal surfaces of

both maxillary and mandibular deciduous 2nd molars to fall in same vertical plane in centric occlusion.

Such an arrangement is called as flush terminal plane. Flush terminal plane is considered to be the ideal

kind of molar relationship in the primary dentition.

Mesial step: In this terminal plane relationship, the distal surface of the mandibular deciduous 2nd

molar is more mesial to the distal surface of the maxillary deciduous 2nd molar (Fig. 21.9B).

Distal step: Here, the distal surface of the mandibular deciduous 2nd molar is more distal to the distal

surface of the maxillary deciduous 2nd molar. In other words, the maxillary 2nd deciduous molar is

ahead of the mandibular 2nd deciduous molar (Fig. 21.9C).

Significance of Terminal Plane Relationship

Determining the terminal plane relationships in the primary dentition stage is of great importance,

because the erupting first permanent molars are guided by the distal surfaces of the 2nd primary molarsas they erupt into occlusion. Thus, the terminal plane relationship of primary dentition largely

determines the type of molar relationship in the permanent dentition.

(Phulari, 2013)

Phulari, R. (2013). Textbook of Dental Anatomy, Physiology and Occlusion. JP Medical Ltd, p.310.