http://www.riodental.com/ well known, top quality, everyone speaks english, they provide the transpo from your US hotel in El Paso to the clinic and back at no extra charge.
Also check out Washington Dental Clinic, Juarez Mx ..couldnt find a site for em but they are equally as well known and provide the same services.
Don't have any doubts about the quality of hygiene, care or work you will receive at either place and they will save you hundreds of dollars..even with the trip expense.