Both Lwena and the nearby Chokwe people of southern Democratic Republic of Congo use this type of mask. It represents the ideal female beauty, Mwano Pwo, and is danced with male counterparts, Chihongo, during initiation ceremonies and other important occasions to bring fertility and prosperity to the village. Most share the depiction of facial scarification patterns, filed teeth, fanciful and inventive hair styles. Despite the mask’s appearance and excellent quality of carving, it was probably made to be sold. This is good news because it means you can afford something just like it for your collection.
I got this picture from a recent posting on an excellent discussion group: African_Arts at https://groups.yahoo.com/. If you have any interest at all in African masks I would highly recommend that you join this group.