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Abstract

Thank you for taking an interest in our article and for your pertinent comments. As you said, to date, there are only a few case reports of paresthesia after tooth movement, with teeth colliding with the inferior alveolar nerve, and all patients reported it occurred soon after the application of intrusive forces or root torque.1Chana R.S. Wiltshire W.A. Cholakis A. Levine G. Use of cone-beam computed tomography in the diagnosis of sensory nerve paresthesia secondary to orthodontic tooth movement: a clinical report.Am J Orthod Dentofacial Orthop. 2013; 144: 299-303Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar,2Mahmood H. Stern M. Atkins S. Inferior alveolar nerve anaesthesia: a rare complication of orthodontic tooth movement.J Orthod. 2019; 46: 374-377Crossref PubMed Scopus (4) Google Scholar When it occurred, the patients reported it resolved shortly after the removal of the orthodontic forces performed on the tooth compressing the inferior alveolar nerve.1Chana R.S. Wiltshire W.A. Cholakis A. Levine G. Use of cone-beam computed tomography in the diagnosis of sensory nerve paresthesia secondary to orthodontic tooth movement: a clinical report.Am J Orthod Dentofacial Orthop. 2013; 144: 299-303Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar,2Mahmood H. Stern M. Atkins S. Inferior alveolar nerve anaesthesia: a rare complication of orthodontic tooth movement.J Orthod. 2019; 46: 374-377Crossref PubMed Scopus (4) Google Scholar Technologies such as cone-beam computed tomography (CBCT) imaging should be used to better visualize anatomic relationships considering the treatment goals and to anticipate eventual injury of the inferior alveolar nerve. Injury of the alveolar nerve is a complication that is more common when there is surgery, such as the extraction of wisdom teeth or the placement of implants. In these situations, rupture of the nerve can occur, and CBCT imaging is more important. In our patient, the risk would be compression, and the injury would be transitory and reversed with suppression of orthodontic strength if this happened (which was not the case).1Chana R.S. Wiltshire W.A. Cholakis A. Levine G. Use of cone-beam computed tomography in the diagnosis of sensory nerve paresthesia secondary to orthodontic tooth movement: a clinical report.Am J Orthod Dentofacial Orthop. 2013; 144: 299-303Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar,2Mahmood H. Stern M. Atkins S. Inferior alveolar nerve anaesthesia: a rare complication of orthodontic tooth movement.J Orthod. 2019; 46: 374-377Crossref PubMed Scopus (4) Google Scholar In orthodontics, it is important to understand that even if we had a CBCT image, it is more important to pay attention to the symptomatology because there are secondary forces or parasitic movements (even with aligners) that may occur and that could compress the alveolar nerve. Thus, even with CBCT, this cannot be fully controlled.3Patcas R. Müller L. Ullrich O. Peltomäki T. Accuracy of cone-beam computed tomography at different resolutions assessed on the bony covering of the mandibular anterior teeth.Am J Orthod Dentofacial Orthop. 2012; 141: 41-50Abstract Full Text Full Text PDF PubMed Scopus (99) Google Scholar In addition, because miniscrews are necessary for patients with this degree of complexity, it becomes even more relevant to evaluate the symptomatology as there are higher forces because of the maximum anchorage control (and then more probability to have parasitic movements) which even if it is very controlled by previously planned ClinCheck, may have deviations from the pattern when the forces surpass what was virtually planned. That situation has clinical repercussions that can be observed in the aligner’s misfit in general in those teeth. A study by Patcas et al3Patcas R. Müller L. Ullrich O. Peltomäki T. Accuracy of cone-beam computed tomography at different resolutions assessed on the bony covering of the mandibular anterior teeth.Am J Orthod Dentofacial Orthop. 2012; 141: 41-50Abstract Full Text Full Text PDF PubMed Scopus (99) Google Scholar revealed that a difference between the clinical and radiologic measurements could be as large as 2 mm, which shows that the average alveolar bone thickness of 1 mm might be missed completely. We can do parallelism to the alveolar canal cortical. The mandibular canal is usually formed by a thin bony plate that can have more of an appearance of trabecular bone; in a few mandibles, there was a thin layer of cortical bone.4Gowgiel J.M. The position and course of the mandibular canal.J Oral Implantol. 1992; 18: 383-385PubMed Google Scholar Thus, we cannot fully predict if the roots are colliding with the alveolar nerve if there is a close relationship between them. We stress that this concept is valid for orthodontics. In patients treated with surgery, we have a different purpose. Therefore, it is most important to observe the symptomatology and remove the applied forces, if present. In addition, because of the high radiation levels associated with the CBCT, this should not be a routine examination. To have a higher control during orthodontic treatments, this examination would have to be performed several times during orthodontic treatment to compensate for the parasitic movements that can occur. Something that is not acceptable clinically. An initial CBCT would be interesting if we wanted a more precise location of the nerve, but it would not completely avoid eventual complications from orthodontic movements. Of course, we have to be careful. The ideal, as you said, would be to have CBCT to clarify if there is an approximation to the nerve; however, in our opinion, it is not mandatory to have full assurance during orthodontic movements. To answer the second question, because our patient has a temporomandibular disorder with an hyperdivergent biotype and mandibular retrusion, it is important to integrate the following issue with relation to the anterior occlusal plane and posterior occlusal plane step. It is significantly correlated with retrusive mandibular/condylar displacement in all skeletal classes, and in skeletal Class II malocclusion, the correlation is highly significant.5G M. C I. P E. Correlation of occlusal-plane-inclination with functional condylar displacement in different skeletal classes.Int J Dent Oral Health. 2020; 6Google Scholar In the literature,6Sato S. Aoki S. Concept of therapeutic mandibular position and its clinical application (Part 1).J Acad Clin Dent. 2013; 33: 254-262Crossref Google Scholar, 7Umemori M. Sugawara J. Mitani H. Nagasaka H. Kawamura H. Skeletal anchorage system for open-bite correction.Am J Orthod Dentofacial Orthop. 1999; 115: 166-174Abstract Full Text Full Text PDF PubMed Scopus (380) Google Scholar, 8Ury E. Hungary. Reproducibility of chin controlled reference position with three registration techniques.Int J Stomatol Occlusion Med. 2008; 1: 21-26Crossref Google Scholar when patients with Class II malocclusion are associated with either mandibular retrusion and temporomandibular disorder, there is a posterior occlusal step, which is the condition presented in this case report. We wanted the counterclockwise rotation of the mandible to improve open bite and facial esthetics. In addition, we have to flatten the posterior occlusal plane (OP), so there is a counterclockwise rotation of the mandible and decompression of the articular disc.7Umemori M. Sugawara J. Mitani H. Nagasaka H. Kawamura H. Skeletal anchorage system for open-bite correction.Am J Orthod Dentofacial Orthop. 1999; 115: 166-174Abstract Full Text Full Text PDF PubMed Scopus (380) Google Scholar To flatten the OP, we could do 2 things: improve the tip back (or occasionally intrude) of the mandibular molars and extrude the maxillary molars. In this patient, as we had a skeletal open bite, we placed miniscrews in the mandible because the mandibular molars are more difficult to intrude than maxillary, in which the bite-block effect is due to 2 aligners interposed between posterior teeth is enough to do this.9Charalampakis O. Iliadi A. Ueno H. Oliver D.R. Kim K.B. Accuracy of clear aligners: a retrospective study of patients who needed refinement.Am J Orthod Dentofacial Orthop. 2018; 154: 47-54Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar In addition, on the smile photograph, we have a normal exposure on posterior maxillary teeth, and as we know, the maxillary molars are due to the bone quality and are easier to have better intrusion control than mandibular molars. Thus, it made perfect sense to put the miniscrews in the mandible and not in the maxilla. The same was reported by Umemori et al7Umemori M. Sugawara J. Mitani H. Nagasaka H. Kawamura H. Skeletal anchorage system for open-bite correction.Am J Orthod Dentofacial Orthop. 1999; 115: 166-174Abstract Full Text Full Text PDF PubMed Scopus (380) Google Scholar that you have mentioned in your commentary. The authors controlled the severe open bite in a hyperdivergent biotype with a convex profile by using fixed titanium miniplates on the mandibular arch and not on the maxillary arch in a conventional technic. Perhaps, the mandibular titanium miniplates were the major reason for the success in controlling the OP flattening. In our patient, we did not fix titanium miniplates but extra-alveolar miniscrews on the mandibular shelf bilaterally. Without any doubt, aligners and miniscrews in the present case report were an asset in the correction of a patient with this complexity. In addition to the cephalometric superimpositions that are undoubtedly a scientifically proven asset, we have a clinical improvement at the dental and facial level, namely in the lip competence that reinforces the success of the present case report. In conclusion, I refer once again that it would be an added value if we had a CBCT, but, in this orthodontic patient, it was not mandatory, considering everything that was said above. I also reinforce the occurrence of counterclockwise rotation of the mandible as a major contribution to close the open bite, promoting the OP control, mainly to at least avoid the extrusion of the mandibular molars (with the aligners and miniscrews), that would have an increased complexity degree for most of the traditional orthodontic treatments. Concern about possible inferior alveolar nerve compression after molar intrusionAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 160Issue 4PreviewWe read with great interest the case report by Pinho et al presenting a successful correction of skeletal open bite by miniscrew-assisted mandibular molar intrusion. (Pinho T, Santos M. Skeletal open bite treated with clear aligners and miniscrews. Am J Orthod Dentofacial Orthop 2021;159:224-33). We appreciated the case report, but we have a concern about possible inferior alveolar nerve (IAN) injury after molar intrusion, considering the molar roots in proximity to the IAN canal. Full-Text PDF