How do I fix my deep mental chin groove? I am very unhappy with my chin. (Photos)

I would not recommend a chin implant for you, as your chin is very well projected the way that it is.  Placing a chin implant would also make your groove worse.  An injectable filler could be used under the groove to help soften it.  There are a variety of fillers that could be used for this purpose.  

You have a few options to improve the crease in your chin. Fillers can soften this area. I’d suggest augmenting your chin with Sculptra and/or Voluma. I hope that helps.

Likely the simplest solution for a prominent mental crease is injections of hyaluronic acid filler such as Restylane which can be performed in the office, or a micro-fat transfer to the area - under local anesthesia.  I would discourage you from getting a chin implant given that you appear to have a normal chin projection in the photos above.  Best of luck to you.

A chin implant will make your labiomental fold deeper. Augmenting the depth of the fold can be done by injectable fillers, fat injections or the placement of a dermal-fat graft from an intraoral approach.

 Hi, I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  From the photos, your chin sone't appear to be weak (see the attached video).  However, the mental crease is indeed deep.  A dermal filler can soften the mental crease. When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  
 Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut segments of bone).  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  
Hope this helps.

a chin implant will make the chin bigger and the crease worse. I think you look great as you are, myself. Not everyone has to look the same.