Among the primary dentition, the maxillary second molar is typically the last tooth to erupt.

- The sequence of primary tooth eruption generally follows a predictable pattern. Initially, the central incisors appear, followed by the lateral incisors, first molars, canines, and finally the second molars.
- Among these, the second molars (both mandibular and maxillary) are the last teeth to emerge in the primary dentition.
- Between the two second molars, the maxillary second molar typically erupts after the mandibular second molar.
- This eruption sequence is important for proper occlusion development and spacing for the permanent teeth that will follow.

Therefore, the correct answer is the maxillary second molar.

Important Points:
- Last primary tooth to erupt: Maxillary second molar
- Eruption order: Central incisors → Lateral incisors → First molars → Canines → Second molars
- Mandibular second molar erupts before maxillary second molar

Reference: Ten Cate's Oral Histology, 8th Edition, Chapter 5: Tooth Eruption and Shedding