The two extra PAs in an 18-20 FMS typically come from which teeth?

• A. Maxillary laterals or maxillary canines
• B. Mandibular second premolars
• C. Maxillary central incisors
• D. Mandibular canines

Answer: (A)

In a full-mouth radiographic survey, you want to ensure every root apex is captured clearly. Sometimes the standard set of periapical images doesn’t reliably include the apices of the anterior maxillary teeth because of overlap and the curvature of the arch. To compensate, two extra periapical images are usually taken from the upper front teeth, specifically from the maxillary lateral incisors or the maxillary canines. These teeth sit in a position where the standard angles can miss their apices, so adding images for them helps guarantee complete visualization of the anterior roots and surrounding bone.