I'd suggest to see a dermatologist to review things carefully and for an up close look a the scalp. There does appear to be an element of traction alopecia here - but there could be other factors as well. Whether or not it's regrowable depends on how long the dreads were used. I'm personally a big believer in treating early traction alopecia aggressively with topical steroids, steroid injections and minoxidil as study after study has confirmed that early traction alopecia is associated with inflammation. Traction alopecia is more advanced can be associated not only with inflammation but also scarring. This is what causes more advanced forms to be permanent. Hair loss after traction alopecia can progress even when the hairstyle was stopped. Traction alopecia does not seem to get the attention it always deserves but aggressive treatment of early traction alopecia can lead to significant regrowth sometimes. Unfortunately not always. All in all, I'd recommend sitting down with a dermatologist to review things carefully. Now is the time to act if there is a potential to regrow hairs. A biopsy can help predict somewhat if there is full growth potential or not, but it's not usually recommended because it too leaves a guaranteed scar. You'll know if about 6 months if regrowth will occur or not. Starting dreads again is likely not advised but these issues are best left to the physician who reviews the whole story and can examine the scalp up close.
