When a piercing is healing it is an open wound and will put you at a highly elevated risk of infection if you have unprotected sex. Even after a piercing is healed, it has an increased potential for small skin tears and other lesions and will slightly increase your chance of infection if you are not using a condom. This applies to tongue piercings, male genital piercings, and female genital piercings.
A dental dam can offer a viable form of barrier protection for use during female oral sex, helping reduce the risk of oral to genital/genital to oral infections.
Piercings should not generally affect the use of condoms or other safe sex measures. In the case of extremely stretched glans jewelry such as a heavy gauge Prince Albert piercing, a condom with an enlarged glans area such as Inspiral Condoms or Pleasure Plus can alleviate pressures in the region.