Which of the following ages is NOT within the active period of the middle palatal suture?

• A. 6 months
• B. 12 months
• C. 7 years
• D. 28 years

Answer: (D)

The midpalatal suture stays open during growth to allow true expansion of the maxilla. In infancy and childhood, and through early adolescence, the suture is still patent, so an active expansion procedure can separate the suture. As growth finishes, the suture gradually ossifies and fuses, with fusion largely complete by late adolescence to early adulthood, making nonsurgical expansion ineffective. Therefore, ages like 6 months, 12 months, and 7 years are still within the active period, while 28 years is not. The age not within the active period is 28 years.