Presurgical Nasoalveolar Molding for Cleft Lip and Palate: The Application of Digitally Designed Molds

Sir: We have read the study of Shen et al.1 with great interest. Because their focus of research is similar to that of our own work, we feel able to comment on this interesting pilot study. The authors report a prospective study including 17 infants undergoing nasoalveolar molding therapy. From an initial maxillary cast, a consecutive series of maxillary casts were designed virtually. Based on these printed casts, the molding devices were manufactured in the conventional method. The software-based design attempted to imitate maxillary segment alignment by a guided reorientation.1 The molding treatment was performed following the principles of Grayson et al.2 and was described as having been performed with the intention of achieving alveolar symmetry.3 Not only was this attempted by elongating the smaller alveolar segment, but also the greater segment was extended and the anterior part was also rotated. The illustrated computer-aided design casts, however, predominantly seem to bend the segment from a 50-degree angle to one of approximately 70 degrees, thereby resulting in a nonharmonic arch with a kink. Therefore, we would like to question this approach, because the intended symmetry may not be achieved. Moreover, the lack of the implementation of a three-dimensional factor for growth might result in an undesired restriction of growth. Without considering transversal maxillary growth, posterior expansion might be blocked; this could be the answer to the static and decreasing dimensions of points T and T′, when the anteroposterior (sagittal) direction slightly increases (T to C2 and T′ to C2′), although without statistical significance. In our own studies, we have empirically implemented a factor for growth, which is currently being refined and is about to be determined automatically by analyzing three-dimensional patient models of the maxilla. This so-called RapidNAM Project will allow us to detect the divided alveolar segments of cleft lip and palate patients to determine an anatomically appropriately shaped alveolar ridge. The ridge is described by curves that are fitted to the alveolar segments and that will provide three-dimensional information over time from a control group without cleft lip and palate.4 Because the molding devices have been customized in the conventional way, the superiority of this new approach with regard to the expenditure of time is not conclusive. Based on our own research, we should mention that this can also be achieved by preconstructing the nasoalveolar molding plates by means of computer-aided design/computer-aided manufacturing.5 DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. None of the authors had any financial or personal relationships with other people or organizations that could have inappropriately influenced this work. ACKNOWLEDGMENT The project RapidNAM for digitization and automation of nasoalveolar molding treatment is supported financially by the Zeidler-Forschungs-Stiftung (Waldkraiburg, Germany). Denys J. Loeffelbein, M.D., D.D.S., Ph.D.Florian D. Güll, M.D.Department of Oral and Maxillofacial Surgery Franz Bauer, M.Sc.Erich Wintermantel, M.D., Ph.D.