Thank you for your question. Bimaxillary protrusion is characterised by protrusive and proclined upper and lower incisors and difficulty closing the lips. Bimaxillary protrusion can also be associated with a gummy smile and an anterior open bite and is seen commonly in African-American and Asian patients. The cause of bimaxillary protrusion is multifactorial and consists of a genetic component as well as environmental factors, such as mouth breathing, tongue and lip habits, and tongue volume.
The usual concerns of patients with bimaxillary protrusion is that they find their teeth protruding and their lips sticking out. As this condition is the malposition of the upper and lower front teeth, it is mainly an aesthetic concern. Calling it an aesthetic concern, does not lessen the individual's perceived need for it to be treated because of the negative emotions perceptions attached to protruding teeth. Furthermore, if the bimaxillary protrusion is associated with difficulty closing the lips, this may be associated with dry lips, thick and overgrowth of the gums (gingiva hyperplasia) due to prolonged mouth breathing and may be associated with difficulty brushing the gums of the front teeth due to its position.
If the bimaxillary protrusion is associated with an anterior open bite, this means that the front teeth are not touching each other and not contributing to the chewing function. Over time, this may result in overuse of the back teeth and excessive wear of the back teeth.
Hope this helps!
Dr Priscilla Lu
BDSc, MDS (Ortho)
9 Scotts Road