Areas where dental assistant salaries fell below the state average include San Antonio-New Braunfels reporting $30,870 per year, Houston-Sugar Land-Baytown reporting $30,790, Amarillo reporting $30,660, El Paso reporting $28,430 and Lubbock reporting $24,250.ay Range. The lowest-paid 25 percent of dental assistants in Texas earned $24,920 per year or less, while the lowest-paid 10 percent earned $20,480 or less per year.