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The mandibular central incisor has the narrowest mesiodistal crown of any tooth; studies confirm this for both permanent and primary dentitions. Because the deciduous (primary) version is even smaller than its permanent successor, the smallest overall mesiodistal width is found in the deciduous lower (mandibular) central incisor [Kuswandari, 2004, PMID 14725813; Harris & Lease, 2005, PMID 15895432].