Complex sentence: It is usually advised to have your cheek pierced slightly higher or lower than where your teeth meet inside the mouth; if this isn't taken in consideration, then the likelihood of biting the back of the stud is greatly increased.
Split into simpler sentences: It is usually advised to have your cheek pierced slightly higher or lower than where your teeth meet inside the mouth. If this isn't taken in consideration, than the likelihood of biting the back of the stud is greatly increased.