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Abstract

To: Editor, The Angle OrthodontistRe: Response to: Dentoskeletal effects of a temporary skeletal anchorage device-supported rapid maxillary expansion appliance (TSADRME): A pilot study. Vassar JW, Karydis A, Trojan T, Fisher J. The Angle Orthodontist. 2016;86:241–249.Thank you for the opportunity to respond to Dr Thakkar's questions regarding our recently published study in your journal. Dr Thakkar is posing some very interesting questions that we want to address.Dr Thakkar suggests that the midpalatal suture could have been used as a marker for skeletal maturity of the stomatognathic system. In our study we were able to identify the midpalatal suture region only in some of our patients. We concluded that the midpalatal suture could not offer an accurate estimate either for the maturation or for the expansion, most likely due to the lower radiation and resolution (0.4 mm) used in our study for patient safety purposes (previous reports used higher radiation CBCTs and higher resolution: 0.25-0.3 mm).1 We addressed this limitation of our sample by dividing our population in two age groups: age group 8-16 years old that corresponds with palatal maturation stage A-C1 (non-fused palatal suture) and skeletal maturation stages CS1-CS4 (Cervical Vertebral Method CVM),2 and age > 16-18 years old that corresponds to more advanced maturation stages.We were able to evaluate the midpalatal suture distance and expansion in some of our patients. Since the mean time between the 1st and the 2nd CBCT in our sample was 7.83±2.49 months, we were able to evaluate the midpalatal suture expansion mainly in those patients where the time between CBCTs was at the lower end of our time range. In patients where the time between CBCTs was at the higher end of our time range, even when the midpalatal suture was identifiable, the bone was already mineralized rendering our measurements less useful.Dr Thakkar raises the most interesting question regarding the effect of RME procedures on circum-maxillary sutures and the anterior face height in hyperdivergent patients. His suggested hypothesis is that the reduction in dental tipping and extrusion resulting from TSAD support would lessen the molar extrusive effect of RME treatment. However, the magnitude of vertical displacement at the circum-maxillary sutures may be a significant contributor to increased anterior face height, especially in the hyperdivergent population. These are very interesting questions, but they were beyond the scope of our study that focused on the assessment of maxillary skeletal expansion and dental tipping using CBCT images and proposed a novel way to quantify the dental tipping effects of temporary skeletal anchorage device–supported RME appliances.Thank you again for the opportunity to discuss very important questions that affect our clinical decisions in selecting the ideal treatment options for our patients. We sincerely hope that the continuous interest in the topic will lead more researchers in studying the above topics.