Class III Bimaxillary Protrusion Correction in an Adult Patient

Bimaxillary protrusion is a condition characterized by protrusive and proclined upper and
lower incisors and an increased procumbence of the lips. As I mentioned in my last published case study involving excessive horizontal and vertical overbite in a teenage patient, “Protrusive and bimaxillary protrusive cases can be challenging to treat. Losing the correct anterior/posterior position can easily happen if the treating practitioner is not careful of the respective facial line angles and the amount of tip and torque necessary in the presenting dentition to achieve a proper final anterior position.”¹ Certain populations have more naturally occurring protrusive profiles, African Americans being one of them. SNA tends to be several degrees higher and the interincisal angle tends to be lower. The prevalence of tongue thrusting, Bolton Analysis discrepancies, and digit habits all must be considered.² In this article we will examine a bi-maxillary protrusive Class III case study and the subsequent treatment undertaken to correct this condition. A 30.10-year-old female patient, I.P. presented to our office with a chief complaint of spacing in her teeth. I.P. exhibited tongue thrusting upon being asked to swallow as well as having difficulty and straining to close her lips. Her bite displayed a ½ step Class III malocclusion on the right molar and a Class I molar relationship on the left side with moderate to severe spacing on both the maxillary and mandibular arches. This resulted in an edge to edge anterior bite for I.P. In addition, the patient exhibited both mouth and nasal breathing. (Fig. 1) The tongue is widely considered the strongest muscle in the body, but actually the masseter is the strongest. Yet the tongue is not just one muscle but a conglomeration of eight separate muscles that intertwine.³ When the force of the tongue is forward with swallowing, spacing can occur between teeth and that can result in lips not being able to comfortably close.