Hair extensions are not done by dermatologists. We diagnose and treat diseases of skin, hair and nails. If there is a medical treatment for your problem we can provide it. You can avail services like hair extensions and weaving at salons and hair spas. Some aesthetic clinics which specialise in trichilogy will have a tie up with technicians who do these procedures. Hairline is one such center. You will probably find more like these if you search the internet. Medicines like minoxidil will improve your hair density unless you have scanty hair since childhood. Warm regards Dr. Rajdeep Mysore. Chirag Hospital Bangalore.
Hair thinning and low volume can be treated by medical and/or surgical techniques which are done by dermatologists. Sorry, hair extension is not done by dermatologists or hair transplant surgeons. You should probably go to a saloon/ beautician for the same.