Regarding Maxillary Impaction for the Treatment of Labial Incompetence in Mobius Syndrome

Abstract

In their recent publication, Vaca and colleagues (2018) report the treatment of a patient with Mobius syndrome who presented with vertical maxillary excess and lip incompetence which was impairing speech. They performed a novel “counterclockwise Le Fort I impaction” and reported patient satisfaction with respect to lip competence and speech at 7 years postoperative. Patient-reported outcomes are increasingly being recognized as important measures of our treatment success, and rightfully so. However, patient satisfaction cannot replace objective outcome measures, particularly when a novel surgical technique is being described. As such, I was surprised to find this article was published without any radiographic data demonstrating that the planned surgical movement was successfully achieved. It would be of great benefit if the authors could provide either cephalometric or Cone-Beam CT superimpositions demonstrating the achieved surgical movement, particularly as the planned “2 mm of posterior impaction and 9 mm of anterior impaction” would be expected to result in a significant anterior open bite secondary to inadequate mandibular autorotation to maintain anterior tooth contact. The concept of mandibular autorotation is critical in the surgical treatment of labial incompetence in hyperdivergent patients, such as those with Mobius syndrome. Posterior maxillary impaction causes the mandible to close about its hinge axis (Sperry et al., 1982; Wang et al., 2006), resulting in an average anterior bite closure of twice the posterior movement (Kassem and Marzouk, 2018), as well as anterior and superior movement of the bony chin. In non-syndromic patients, vertical changes of the soft tissue chin and lower lip approximate those of the underlying hard tissues at approximately a 1:1 ratio (Jensen et al., 1992), and as such, clockwise maxillary impaction with mandibular autorotation will produce improved lip competence through elevation of the lower lip. It is for this reason that the clockwise maxillary impaction is the surgical movement of choice in many patients with Mobius syndrome, particularly those with anterior open bite secondary to trigeminal nerve involvement (Instrum, 1999; Chou et al., 2010). This stands in contrast to the authors’ unsupported assertation that clockwise maxillary impaction is associated with decreased lip competence and increased incisor display. I encourage the authors to revisit this case. While their focus on patient satisfaction is admirable, the absence of objective outcome measures limits what can be learned from their report. As we focus more on patient-reported outcomes, we should all remember that these supplement rather than replace objective outcomes. If we limit our assessments to “the patient was satisfied,” we do disservice to ourselves and our patients.