Author's response.

Abstract

Thank you for inquiring about the article, “Nonsurgical correction of a severe anterior open bite with mandibular molar intrusion using mini-implants and the multiloop edgewise archwire technique” (Am J Orthod Dentofacial Orthop 2018; 153:577-87). Indeed, the initial dental casts had 32 teeth (including third molars) although intraoral photographs and radiographic films had those teeth missing. Initial dental casts were obtained on the first visit in the private practice where treatment was conducted. But the appointment for imaging acquisition was scheduled after all third molars had been extracted, because most private practices in the country do not have x-ray machines, and patients are regularly referred to an outside radiology laboratory to acquire panoramic and lateral cephalometric radiographs. Counterclockwise rotation of the mandible, although small, did indeed occur. The last line of the mandibular teeth measurements, and possibly one of the most important, was accidentally deleted from the cephalometric measurements table. In that line, the measurement 6-GoMe (distance of the mesiovestibular cusp of the first mandibular molar to the gonion-menton line) was indicated 46 mm before treatment and 43.5 mm after treatment and remained stable 5 years after retention. The reduction was 2.5 mm, demonstrating clear molar intrusion. FMA reduced from 42° to 41° and then 40° after retention. SNB also increased from 73° to 75° and then 78° after retention. The explanation missing from the article was that although maxillary molars extruded ∼1 mm, the mandibular molar intrusion, along with intrusion of premolars, was greater than the amount of the maxillary first molars' extrusion, therefore inducing mandibular counterclockwise rotation. Furthermore, one will notice that maxillary superimposition did not include the maxillozygomatic temporal sulcus, the most stable area for superimposition in the maxilla, because the superimposition used in this article was the palate curvature. The choice for this type of maxillary superimposition might have increased the amount of extrusion seen in the first maxillary molars. The bite closure change, as seen on all superimpositions, occurred mostly by the extrusion of maxillary and mandibular incisors and secondarily by the intrusion of maxillomandibular first molars. Tongue posture/thrust habit was a problem detected before initiation of treatment, which along with condyle resorption, might have been the cause of failure from previous orthodontic treatment, as reported in this case, and, if not controlled, could induce anterior open bite relapse.1Bosio J.A. Justus R. Treatment and retreatment of a patient with a severe anterior open bite.Am J Orthod Dentofacial Orthop. 2013; 144: 594-606Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar, 2Justus R. Correction of anterior open bite with spurs: long-term stability.World J Orthod. 2001; 2: 219-231Google Scholar The choice for controlling pernicious habit is a matter of personal treatment preference, which in this clinical case was not chosen. The only attempt to control the habit was the delivery of a Hawley retainer with a hole in the palate and verbal instructions on how to correct deglutition habits. If the patient returned to the habit, then open bite relapse might have been, in part, the cause of the small open bite seen at the 50 months' visit.