We thank Dr Mathur and his group for their interesting comments regarding in our article. Below are our responses to the questions that were asked.
Our previous studies have also shown that bone-anchored maxillary protraction treatment did not produce downward rotation in the posterior region of the maxilla. We hypothesized, in our discussion, that the center of resistance of the maxilla might not be located above the maxillary canine by the infrazygomatic buttress as proposed by Teuscher or Hata et al but, rather, posteriorly to it. Under normal circumstances, counterclockwise rotation of the mandible is unfavorable and often contraindicated in Class III patients. Our protocol produced closure of the gonial angle with significant distal displacement of the posterior ramus. This, combined with slight distalization of the condyles and corresponding remodeling of the glenoid fossa, minimized the forward displacement of the chin while maintaining the mandibular plane angle. The 3-dimensional data from this study will be published in the July issue of the AJO-DO.
The study of Cha and Ngan does not show the superiority of 1 design of bone plates relative to another. They cited the article of Lee et al describing an in-vitro finite element model study of different directions of traction, using a C-design vs a Y-design of bone anchor, with screws of different dimensions than those in this study; therefore, those results cannot be compared with ours.
The literature reports a broad range of forces for effective Class III orthopedic traction. With skeletal anchorage, the protraction appliances no longer need to be attached to the teeth, so effective orthopedic results are obtained by lower forces. Our studies have shown that effective orthopedic traction can be obtained with lower force levels.
The actual positions of the plates in the maxilla and the mandible are shown in Figures 1 and 9. The skull and 3-dimensional model renderings show the positions of the plates much more clearly and without the distortions of a panoramic x-ray.
The Wits appraisal was not used to assess skeletal changes in this study. Instead, we registered our T1 and T2 cone-beam computed tomographs on the cribiform plate and the anterior cranial fossa, and evaluated the midface changes such as the maxilla and the zygomas using 3-dimensional superimposition and analysis software.
The concept that loosening the circummaxillary sutures helps to facilitate the orthopedic effects of maxillary protraction is controversial; Vaughn et al showed no difference between maxillary protraction with rapid palatal expansion and without it. Furthermore, a recent 3-dimensional study evaluated the effects of rapid palatal expansion on the circummaxillary sutures. The authors reported significant increases in the openings of the intermaxillary, internasal, maxillonasal, frontomaxillary, and frontonasal sutures, but no changes in the frontozygomatic, zygomaticomaxillary, and zygomaticotemporal sutures. Interestingly, the frontozygomatic, zygomaticomaxillary, and zygomaticotemporal were the most affected sutures in our study (Fig 9). These findings suggest that effective protraction of the maxilla can be obtained without loosening of the circummaxillary sutures.