What age is old enough for a male chin implant?

It's acceptable undergo a chin implant at age 18 since the mandible has stopped growing at that point. Chin implants are manufactured in a large array of thicknesses, sizes, and shapes. They're usually placed under local anesthesia through submental incision as an outpatient procedure.

The lower jaw rarely grows to age 19 unless it is an 'overgrowth' problem eg underbite due to the lower jaw. Underdeveloped lower jaws can have a genioplasty from an early age - implants are not as ideal since they fall back into the softer lower jawbone at a young age.