We congratulate Echchadi et al for their wonderful treatment of a patient reported in the July issue (Echchadi ME, Benchikh B, Bellamine M, Kim SH. Corticotomy-assisted rapid maxillary expansion: a novel approach with a 3-year follow-up. Am J Orthod Dentofacial Orthop 2015;148:138-53). The article introduced us to corticotomy-assisted rapid maxillary expansion to treat a severe maxillary transverse discrepancy in a skeletally mature patient. The patient had a fine profile and proper occlusion after treatment.

As shown in Table III, both buccal alveolar bone and palatal alveolar bone thicknesses were increased at the root apex level and at the middle of the root level. Could the authors explain how to determine whether the plane was comparable between pretreatment and posttreatment? Since both buccal and palatal alveolar bone thicknesses increased, did the total alveolar bone volume also increase after treatment? Another concern was maxillary posterior tooth buccal inclination. The maxillary posterior tooth had about a 10° average buccal inclination between pretreatment and posttreatment, as described in Table IV. Both the maxillary posterior tooth inclination changes and the alveolar bone expansion contributed to the maxillary arch expansion. What proportion of each factor contributed to the maxillary arch expansion? Which contributed more in this case? We appreciate the authors’ efforts to share the experience with the readers.