The accuracy and retention of presurgical infant orthopaedics constructed from different polymer materials: A comparative study

Abstract

Objectives: This laboratory-based study aimed to evaluate and compare the accuracy and retention of moulding plates when used as pre-surgical orthopaedic appliances (PSIOs) for infants with cleft lip and/or palate (CL/P). Methods: Ten moulding plates were fabricated from three different materials (total sample size: 30), including polymethyl methacrylate (PMMA), a hard clear aligner (PET-G polymer), and a dual-layered hard and soft clear aligner (mixed PET-G/EVA) on ten three-dimensional (3D) printed working models. Accuracy was evaluated by measuring the virtual gap between the data acquired from the moulding plate and the working model after the optical scanning at each of the designated 36 points for each plate. Exocad software was used to facilitate all virtual alignments and measurements. Retention was measured using a digital gauge that quantified the traction force required to separate the plates from the retention test cast (a soft resin printed cast). Results: PET-G plates exhibited the best fit with the working cast, with overall adaptations of 0.146 0.012 for PET-G, 0.250 0.073 for PET-G/EVA, and 0.294 0.113 for PMMA. For region-specific misfit, PET-G plates exhibited superior accuracy across all regions, with mean discrepancies of 0.16 0.08 mm, 0.15 0.061 mm, and 0.12 0.128 mm in the anterior, middle, and posterior regions, respectively. Retention for PET-G was significantly higher than the other materials, with a mean of 3.34 N 0.487, as opposed to 1.65 N 0.331for PMMA and 1.27 N 0.239 for PET-G/EVA (P < 0.05). Conclusions: Moulding plates constructed from PET-G exhibited a better fit and higher retention than those made from PET-G/EVA and PMMA. Clinical significance: Collectively, our findings suggest that the selection of PET-G for PSIO appliances could have clinical significance by potentially improving treatment outcomes in infants with CL/P.