The superior labial frenum: a histologic observation.

Superior labial frena obtained from cadavers or frenectomies were examined histologically. The frena were covered by stratified squamous nonkeratotic, orthokeratotic, or parakeratotic epithelia, depending upon the gingival extent of the frenum. In addition to the normal components of dense, irregular, collagenous connective tissue, almost all frena contained myelinated nerve fiber bundles and small vascular channels. Additionally, 35% of the frena examined contained a few small skeletal muscle fibers.