Mesial Occlusal

When the mesial buccal cusp of the maxillary first molar is distal to the mesial buccal cusp of the mandibular first molar.

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Mesial refers to the side or surface of a structure that is closer to the midline of the body or to a specific reference point. In dentistry, it is used to describe a tooth surface that is closer to the front of the mouth.

The concavity that forms on the mesial aspect of maxillary first premolars is called the cuspid groove. It is the result of the first premolar having both a buccal and palatal root. The groove functions as an alignment guide for the maxillary cuspid as it descends into the mouth.