From Waste to Utility: Recycled PET as a 3D Printing Material in Dentistry: An In vitro Study

Abstract

The overuse of plastics in the past decade raised significant global concerns, prompting a shift toward sustainable materials to mitigate plastic consumption. Among these efforts, recycling post-consumer plastic waste has emerged as a critical focus area. This study aimed to explore the potential of post-consumer recycled polyethylene terephthalate (PCR rPET) as a sustainable alternative to virgin plastics, focusing on the development of a novel 3D printable filament for dental applications. Two types of PCR rPET pellets were collected from commercially available sources in India, one was made from processed plastic waste and directly made to pellets (PCR rPET-d). The other pellets had undergone additional solid-state polymerization (SSP) to increase their density and extrudability (PCR rPET-s). Material characterization was conducted for both the test materials using Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and melt flow index (MFI) testing. A sample size of 10 was used for these analyses. Subsequently, the pellets were extruded into 1.75 mm diameter filament using a traditional twin-screw extruder. The filament extrudability was recorded by observing the rate of flow while extrusion and measuring the diameter of resultant filament. The data were analyzed using descriptive statistics to identify trends and assess the material’s suitability for dental applications, including model preparation, surgical guides, temporary prostheses, and custom trays. The PCR rPET-s material showed promising extrudability and filament production potential. However, challenges such as excessive flow and uneven heating during extrusion resulted in a narrow filament diameter of 1.2mm (± 0.05 mm). PCR rPET-d, showed blackening and bubbling while extruding making it unsuitable. Despite the challenges encountered, PCR rPET-s demonstrated considerable potential as a sustainable alternative in dental prosthesis fabrication. Further optimization of extrusion parameters and equipment design is needed to improve filament consistency and quality. This research highlight the importance of future advancements in sustainable manufacturing techniques by optimizing extrusion processes for broader applications.