HyeRan Choo, HyoWon Ahn

- Korean J Orthod 2024;54:69-73

I appreciate the authors’ pioneering approach with the alveolar molding plate for unilateral cleft lip and palate treatment. To gain a deeper understanding of your work, I have a few inquiries.

Thank you so much for these thoughtful inquiries. We are very excited to share more details on how to implement the Biocreative Alveolar Molding Plate Treatment (BioAMP).

A1. Thank you for the insightful question and astute observation. BioAMP does not use conventional retention mechanism such as mechanical lock into cleft undercuts; instead, it is retained by implementing a spatial mechanism incorporating the nasal stent wire on the same day as the BioAMP delivery. Therefore, the nasal stent wire must remain in passive contact with the inner surface of the nasal dome at all time so as not to exert any springiness. Any deflection will cause the BioAMP to get dislodged vertically and the patient will not tolerate the treatment. Spatial equilibrium is established in a shape of pyramid by four muscular or cartilaginous boundaries: the tongue as the inferior boundary, the bilateral pterygomandibular raphes as the posterior boundary, the face tapes across the labial cleft as the anterior boundary, and the nasal dome as the superior boundary. In other words, the BioAMP is designed to be stabilized into its desired location guided by these structures. When the baby opens the mouth, the posterior border of the BioAMP drops slightly while being maintained by the pair of tapes that connect to the button of the device anteriorly. When the mouth closes, the loose device will return to sit on its desired location by the tongue pressure inferiorly, the pterygomandibular raphes posteriorly the nasal stent wire superolaterally, and the pair of face tapes that connect to the button of the device anteriorly. Different from conventional taping methods, it is crucial that the two tapes attached to the button of the device remain passive at all times. If they become active with tension, the BioAMP will be displaced intraorally and the baby will not tolerate the treatment.

A2. The biggest strength of BioAMP is allowing the maxillary alveolar segments to grow maximally, conforming to an ideal arch form in harmony with the mandibular arch. Splitting the BioAMP takes less than 10 seconds using a saw-shape bur. Filling and curing the gap using fresh acrylic takes less than 1 minute. If the interalveolar gap is disproportionately wide and it seems unrealistic to expect natural growth in the following 2 month to sufficiently reduce the interalveolar gap to 1 mm prior to lip repair surgery, then treatment is started with active constriction weekly for a few weeks. If the baby seems to be growing exceptionally well during the activation stage, then there is no longer a need to activate the screw. I may possibly need a reversal of activation if the interalveolar gap approximates quickly by the baby’s natural growth alone, which is a rare occurrence.

A3. The purpose of pre-programming the ideal arch form (extensive, complete wax-up) is to eliminate the need for the operator’s responsiveness to weekly treatment progress. As long as the baby grows, the growing maxillary alveolar bones can only grow into areas of space and the pre-programmed arch shape of the BioAMP will guide them to conform to the arch form that is designed at the onset of the treatment. Therefore, the BioAMP wax-up needs to be fabricated in a manner to define growth of the maxillary alveolar bone segments: build the wax on the areas where the maxillary alveolar bone segments need to grow into and in a shape that the segments can look like at the end of the treatment. Then, the maxillary alveolar bone segments will certainly grow into that wash-out wax-up space inside the BioAMP and adapt to the expected arch form by the end of the treatment. When the vertical discrepancy of the alveolar cleft is severe, there is sometimes a need to grind off the areas where labial or buccal frenum get irritated as the vertical discrepancy reduces with the treatment. It only takes less than a few seconds to do so. Aside from that, no additional adding or grinding of acrylic is supposed to be necessary during the treatment if the wax-up (pre-programing) and fabrication of the BioAMP were done adequately during the device fabrication stage. An important technique in ensuring the accuracy of the pre-programming is to make sure that the hamular notch areas (both sides) are captured during the oral impression/stone model fabrication, and to trim the posterior border of the model properly with even distance from each hamular notch. This will enable identification of the true median plane of the maxillary arch, which will assure the design of the ideal maxillary arch form is in line with the maxillary and facial midline.