What is the best way to treat my vertical forehead dent? (Photos)

Thank you for the photographs, although in-person evaluation is essential.
It is possible that the dent is due to strong Glabellar-complex muscles, which can be treated with neurotoxins such as Botox/Dysport and Xeomin. 
This part of the face is considered a "dangerous zone" (although there are no "safe zones" in the entire face) due to anatomical location of the supratrochlear blood vessels. An accidental injection of the filler can cause compications like blindness. 
However, sometimes even prominent veins can cause such a depression on the forehead. 
Get a consultation with an expert aesthetic physician and discuss all options.
Good luck and best wishes.
Dr. Shanthala

The photos suggest that the "dent" may actually be resulting from tension within the expression muscles of the glabella to the sides of the depression. If this is indeed so, then the use of a neuromodulator, such as Botox, Dysport or Xeomin, would help to reduce the tension and lower the "mounds" to the sides of the dent, in effect smoothing the entire region. If filler is still needed to achieve further smoothing, then a soft, cohesive filler, such as Belotero Balance, which can be injected quite superficially without worry of causing the unwanted, bluish Tyndall Effect when injected higher up in the skin, may further improve the overall appearance. While your concerns about problems from injecting fillers in this region are legitimate, in experienced hands, these are quite rare and actually have been more associated with the use of thick volumizing agents, such as fat injections in this location. Make sure you consult with a board certified aesthetic physician with experience and expertise in nonsurgical facial rejuvenation using injectable fillers and volumizers. Good luck to you. 

This indentation is something that comes from too many frowning motions.  After a period of time it needs to have both filler and Botox to get back to where it was.  I generally use Restylane for this area but it is a tricky area so you need to make sure that you are with someone who knows what they are doing. Good luck!

Based on your photographs I think Botox would be the best option for you, to start. Although, using fillers on the upper half of the face comes with some risks, it might be an option. I would suggest you consult with a cosmetic Dr so he or she can determine the best treatment for you.

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  With that
being said, based on your photographs, it is likely an overactive corregator muscle and I would recommend starting with botox treatment. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon

Indentations in the forehead do not just suddenly appear for no reason. The pictures are not adequate for me to give a definitive view, but you will certainly need to be investigated to exclude a diagnosis of scleroderma en coup de sabre. Make sure you see a doctor who does more than cosmetic surgery only who will be able to look into this for you. 

You will like need a combination treatment including a dermal filler and Botox or Dysport. See a professional for a formal consultation.

Thank you for your photo. For wrinkles on the forehead you could try Botox or Dysport. Both injectables are good options to consider because it targets the nerves controlling these muscles, causing the muscles to relax. The result is a temporary soothing of wrinkles caused by overactive muscles. For more information, please get a in person consultation from a board-certified dermatologist. 

Hello There,
It is difficult to tell from the photo, but I agree that it may be the glabella. I would treat the area with Botox or Dysport. This will help minimize the protrusion of the muscle with expression. If there are more noticeable lines or a deeper depression, a thin filler such as Restylane Silk or Refyne may be a great option. 
There is a risk for blindness involved with both toxins and fillers, but only if injected incorrectly into the blood vessels. Finding an experienced injector is key.
Hope this helps,
Javad Sajan, MD

Thank you for your question and for sharing your photographs.  Based on your narrative and photos, a combination approach using Botox and filler would likely work best.  Please be sure to see an expert injector for an in-person consultation to fully discuss your goals and expectations in order to determine the best treatment plan.  Hope this helps and best wishes!