Chin surgery, also known as genioplasty or mentoplasty, is a cosmetic surgical procedure that aims to enhance the appearance of the chin by reshaping it or augmenting its size. 

This procedure is performed to increase the size and projection of a recessed or weak chin. It is typically achieved using implants or by repositioning the chin bone. The surgeon makes an incision either inside the mouth (intraoral incision) or under the chin (submental incision) to create a pocket for the implant or manipulate the bone. Implants can be made of silicone, porous polyethylene, or other biocompatible materials. The implant is placed over the chin bone or secured to the bone with screws.