Comparison of 3D-Printed Custom vs. Conventional Mini-implant Assisted Rapid Palatal Expanders (MARPE) in Adult Maxillary Expansion

Introduction: Maxillary expansion has been a treatment of choice for correcting transverse skeletal discrepancies, especially in growing patients. For older patients, Mini-implant Assisted Rapid Palatal Expansion (MARPE) offers a promising treatment option. This study compares the treatment outcomes of Conventional MARPE (MSE-II) and Custom 3D-printed MARPE. Methods: This retrospective study analyzed CBCT images from 42 patients aged 16 to 35 years, comparing measurements before (T1) and after (T2) expansion. The conventional (n=21) and custom (n=21) MARPE groups were matched with age and sex. Skeletal and dental changes were evaluated measuring twelve distances and four angles using Dolphin Imaging Software (Chatsworth, Calif). The measurements included frontozygomatic and maxillary widths, nasal cavity width, and dentoalveolar inclination. The effectiveness of each appliance was evaluated based on the maxillary expansion to screw opening ratio, magnitude of expansion, and successful correction of transverse discrepancy. Results: The custom MARPE group demonstrated a significantly greater increase in width across various anatomical landmarks compared to the conventional group. The custom MARPE group achieved nearly a 1:1 ratio of maxillary expansion to screw opening, while only half of expansion screw opening translated to maxillary expansion in conventional MARPE group (P = 0.0001). Logistic regression showed that the odds of successful transverse discrepancy correction were 8.7 times higher with custom MARPE. Conclusions: Custom 3D-printed MARPE can be more effective than conventional MARPE in older patients. The findings of this study suggest that a personalized appliance design and proper mini-implant placement in areas of higher bone density can enhance treatment outcomes.