Comparative evaluation of the dimensional changes of flowable and packable composite attachments in clear aligner therapy at varying time intervals using scanning electron microscopy

Introduction: Attachments play a key role in improving the efficiency of clear aligners (CA) during orthodontic treatment with flowable composite resins (FCR) and packable composite resins (PCR) being the most commonly used materials.The extent of wear of the attachments dictates the action of the aligners.The present study aimed to quantify the changes occurring in different areas of the attachments of FCR over time as compared to PCR.Materials and Methods: Four models were prepared with dental stone comprising 6 extracted teeth each (4 premolars and 2 molars).Rectangular attachments of standardized 3×2×1mm dimensions were placed on all the extracted teeth using the materials FCR and PCR for two models each respectively.CAs were fabricated for each model using polyethylene terephthalate-glycol.The attachments were analyzed for length, width, and height at the occlusal third, middle third, and cervical third using a scanning electron microscope at the time of placement of the attachments (T0) and after 45 days (T1) and 90 days (T2) respectively.Results: At T0, the total mean height of the FCR attachments was 2.75 + 0.32 mm, and that of the PCR attachments was 2.76 + 0.25.The height was reduced to 2.39 + 0.37 mm for FCR attachments and 0.24 + 0.28 mm for PCR attachments after 45 days.At the end of 90 days, the total mean height of the attachments was 1.99 + 0.5 mm and 2.15 + 0.3 mm for FCR and PCR attachments respectively and the difference between them was statistically significant.After 90 days, the length of FCR attachment was significantly higher (p