Could a dds (general dentist) do crown lengthening, or should i seek a specialist?

Depends: As a periodontist, I do crown lengthenings every day. Technically it is a simple procedure that dentists that routinely do surgery can accomplish in there office, if they have experience. Generally more crown lengthening than less is required to have long term success and not just "get by" with the ability to take a crown impression. Recurrent decay, and chronic inflammation can occur if not.

Either: A crown lengthening is a procedure usually performed by a periodontist or specialist of the gums and bone that support your teeth. Some general dentists that have had training in such procedure are experienced and competent enough to do it, usually for a lower fee. Most of the time, you'll find that a general dentist will refer you to a specialist for this kind of procedure.

Yes: Now with the advancement of laser, crown lengthening surgery is becoming more and more controlled and easy to perform. A general dentist has a license to perform any procedure that he felts competent to perform, as long as it follows the standard of practice.