Authors' Reply to Letter to the Editor "Effects of airway evaluation parameters on the laryngeal view grade in mandibular prognathism and retrognathism patients".

We appreciate the thoughtful comments about our article from Prof. Song [1]. Prognathism (or prognathia) is the positional relationship of the mandible and/or maxilla with the skeletal base, where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull. Retrognathism (or retrognathia) is a type of malocclusion that refers to the abnormal posterior positioning of the maxilla or mandible, relative to the facial skeleton and soft tissues [23]. In general dentistry, oral and maxillofacial surgery, and orthodontics, these are assessed clinically or radiographically (cephalometrics). The clinical diagnosis of prognathism and retrognathism is based on multiple points and lines such as A (subspinale), B (supramentale), M (junction of nasomaxillary and nasofrontal suture), N (nasion), Or (orbitale), P (porion), Pog (pogonion), S (sella), facial plane (N-Pog), AB plane, SN plane, and occlusal plane [45]. However, there is no established method for the diagnosis of prognathism and retrognathism. Therefore, clinicians have been diagnosing and treating based on their own methods. In our study, all subjects had a cephalometric radiograph because they were patients who were receiving dental treatment. Since there is uncertainty in the diagnosis, retrognathism was diagnosed and analyzed using the ANB angle on a cephalometric radiograph in our study. When a cephalometric radiograph was not available, diagnosis was made based on methods that used the points and lines of the soft tissues. However, we do not have a good recommendation. In addition, we think that using the distance between the incision superius and inferius to make a diagnosis would be inappropriate because that varies depending on the angle of the incision, not the maxilla or mandible. There is also no established criteria for classifying the severity of the retrognathism. Hence, we could not measure the relationship between the severity of the retrognathism and grade of the laryngeal view.

We read the article about the ratio of height to thyromental distance (RHTMD) and upper lip bite test (ULBT) that you presented [6]. Thank you for presenting this very interesting article to us. We think that RHTMD and ULBT will help predict a difficult airway, but RHTMD would not be related to the retrognathism in our article. Further studies related to ULBT are needed because it would be associated with retrognathism. Thank you for your thoughtful comments on and recommendations for our article.