In a normal Class I occlusion, tooth #5 (maxillary right second premolar) occludes with which surfaces?

Correct answer: A. The distal of tooth #28 and the mesial of tooth #29

• A. CORRECT. In normal occlusion, each posterior tooth (with the two exceptions noted below) contacts TWO opposing teeth, and the maxillary tooth sits DISTAL to its mandibular counterpart. Tooth #5 is the maxillary right second premolar; its mandibular counterpart is #28 (mandibular right second premolar). Tooth #5 therefore occludes with the DISTAL portion of #28 and the MESIAL portion of #29 (mandibular right first molar).
• B. A single-tooth contact is incorrect for a premolar — and #27 is the mandibular right canine, which is too far anterior.
• C. A single contact with #29 alone is incorrect; #5 contacts two teeth.
• D. This pairing is displaced one tooth anteriorly and would describe the relationship of the maxillary FIRST premolar, #4.

Note: The two exceptions to the two-tooth contact rule: the MANDIBULAR CENTRAL INCISOR and the MAXILLARY THIRD MOLAR each oppose only ONE tooth. The reliable method is to identify the counterpart tooth by name and arch, then remember that the maxillary tooth sits half a tooth DISTAL.