Missing Permanent Teeth (Hypodontia/Oligodontia).  Third molars are the teeth found to be most commonly missing (about 23% of the population).  Second premolars are next followed by maxillary lateral incisors.  Keeping mandibular second deciduous molars presents an interesting situation since they tend to be much wider mesio-distally than the underlying premolars (average 1.7mm wider).