A frenum is a naturally occurring muscle attachment. A frenum can be found under the tongue, in the inner aspect of the middle of the lip (either upper or lower) and along the cheeks, attaching the cheeks to the gums.
If the muscle’s attachment under the lip is excessively large, it can prevent the teeth from coming together, resulting in a gap between the front teeth. Release of the frenum from the gum (frenectomy) will allow the teeth to come together. A lack of gum tissue around a tooth in conjunction with a high frenum attachment (closer to the biting surface) will exaggerate the pull on the gum margin. This can result in gum recession, leading to loss of support of that tooth and increasing the likelihood of tooth sensitivity. A frenectomy will increase the stability of the area. A gum graft may be recommended if the recession is significant.