Case 2: The incisor requiring extraction
A 38-year-old woman attended the surgery requesting extraction of tooth #22, which was failing despite previous endodontic therapy and multiple attempts at retreatment. Before extraction and immediate placement of a dental implant, a CBCT scan and intra-oral scan were taken. Using the preoperative intra-oral scan, a provisional retainer was planned as a contingency appliance in the event that primary stability could not be achieved.
3D-printed aligners and retainers have gained significant interest in recent years owing to their design flexibility, material-specific properties such as shape memory behaviour and reported improvements in trueness and precision compared with their traditional thermoformed counterparts.5 However, evidence on long-term biocompatibility remains limited, and in vitro studies have reported potential concerns regarding cytotoxicity and residual monomer release from 3D-printed aligners.6, 7
The provisional retainer was designed in Medit Design (Fig. 4a). An offset of 0.1 mm was set, and the retainer was designed with a thickness of 0.8 mm. Support placement and slicing were performed in Composer, and supports were placed only at the retainer borders, according to the resin manufacturer’s instructions for use (Fig. 4b). The retainer was printed from dx direct aligner resin, a material cleared for the printing of aligners and retainers, on the Max 2 using an UltraGLOSS LIFT tray (Asiga) to improve the clarity of the final print and reduce the amount of post-processing required (Fig. 5a).
The retainer was washed with the supports still attached in isopropyl alcohol in an ultrasonic unit before final polymerisation in an Otoflash G171-6 (NK Optik) under nitrogen, according to the manufacturer’s instructions (Fig. 5b).
