Poom Narongdej

Glass fiber-reinforced polymer (GFRP) composites are widely utilized across industries, particularly in structural components exposed to hygrothermal environments characterized by elevated temperature and moisture. Such conditions can significantly degrade the mechanical properties and structural integrity of GFRP composites. Therefore, it is essential to utilize effective methods for assessing their hygrothermal aging. Traditional approaches to hygrothermal aging evaluation are hindered by several limitations, including time intensity, high costs, labor demands, and constraints on specimen size due to laboratory space. This study addresses these challenges by introducing a facile and efficient alternative that evaluates GFRP degradation under hygrothermal conditions through surface wettability analysis. Herein, a glass fiber-reinforced benzoxazine (BZ) composite was fabricated using the vacuum-assisted resin transfer molding (VARTM) method and was aged in a controlled humidity and temperature chamber for up to 5 weeks. When analyzing the wettability characteristics of the composite, notable changes in the contact angle (CA) and contact angle hysteresis (CAH) were 21.77% and 90.90%, respectively. Impact droplet dynamics further demonstrated reduced wetting length and faster droplet equilibrium times with the prolonged aging duration, indicating a progressive decline in surface characteristics. These changes correlated with reductions in flexural strength, highlighting the surface’s heightened sensitivity to environmental degradation compared with internal structural integrity. This study emphasizes the critical role of surface characterization in predicting the overall integrity of GFRP composites.

Despite the robustness of thermosetting coatings in various applications, prolonged exposure to acidic environments can cause gradual deterioration, leading to structural or functional damage. This study investigates composite materials comprised of cycloaliphatic epoxy resin (CER) and benzoxazine (BZ) at three different weight ratios: 50:50, 25:75, and 0:100. These composites were exposed to nitric acid, simulating acid rain, for durations ranging from 1 to 5 h. The specimens were characterized for weight change, mechanical properties (flexural strength and short beam strength), and surface properties (contact angle and contact angle hysteresis). Although minimal changes in the physical and mechanical properties of both homopolymer and copolymer composites were detected after short acid exposure (up to 5 h), surface wettability analysis via static contact angle and contact angle hysteresis revealed more pronounced deterioration. The static contact angle decreased by 24.96% and 28.32% for homopolymer BZ and copolymer BZ-CER composites, respectively. Contact angle hysteresis increased by 19.39% and 27.80% for 5 h acid-exposed homopolymer BZ and copolymer CER, respectively. This study underscores the utility of surface wettability analysis as a valuable tool for monitoring deterioration from acidic aging in polymers, particularly in BZ-CER systems used in structural and high-performance applications.

In recent years, additive manufacturing (AM) has been recognized as a transformative force in the dental industry, with the ability to address escalating demand, expedite production timelines, and reduce labor-intensive processes. Despite the proliferation of three-dimensional printing technologies in dentistry, the absence of well-established post-processing protocols has posed formidable challenges. This comprehensive review paper underscores the critical importance of precision in post-processing techniques for ensuring the acquisition of vital properties, encompassing mechanical strength, biocompatibility, dimensional accuracy, durability, stability, and aesthetic refinement in 3D-printed dental devices. Given that digital light processing (DLP) is the predominant 3D printing technology in dentistry, the main post-processing techniques and effects discussed in this review primarily apply to DLP printing. The four sequential stages of post-processing support removal, washing, secondary polymerization, and surface treatments are systematically navigated, with each phase requiring meticulous evaluation and parameter determination to attain optimal outcomes. From the careful selection of support removal tools to the consideration of solvent choice, washing methodology, and post-curing parameters, this review provides a comprehensive guide for practitioners and researchers. Additionally, the customization of post-processing approaches to suit the distinct characteristics of different resin materials is highlighted. A comprehensive understanding of post-processing techniques is offered, setting the stage for informed decision-making and guiding future research endeavors in the realm of dental additive manufacturing.

Clear aligners have revolutionized orthodontic treatment by offering an esthetically driven treatment modality to patients of all ages. Over the past two decades, aligners have been used to treat malocclusions in millions of patients worldwide. The inception of aligner therapy goes back to the 1940s, yet the protocols to fabricate aligners have been continuously evolved. CAD/CAM driven protocol was the latest approach which drastically changed the scalability of aligner fabrication—i.e., aligner mass production manufacturing. 3D printing technology has been adopted in various sectors including dentistry mostly because of the ability to create complex geometric structures at high accuracy while reducing labor and material costs—for the most part. The integration of 3D printing in dentistry has been across, starting in orthodontics and oral surgery and expanding in periodontics, prosthodontics, and oral implantology. Continuous progress in material development has led to improved mechanical properties, biocompatibility, and overall quality of aligners. Consequently, aligners have become less invasive, more cost-effective, and deliver outcomes comparable to existing treatment options. The promise of 3D printed aligners lies in their ability to treat malocclusions effectively while providing esthetic benefits to patients by remaining virtually invisible throughout the treatment process. Herein, this review aims to provide a comprehensive summary of studies regarding direct-3D printing of clear aligners up to the present, outlining all essential properties required in 3D-printed clear aligners and the challenges that need to be addressed. Additionally, the review proposes implementation methods to further enhance the effectiveness of the treatment outcome.