ABSTRACT
Fused Filament Fabrication (FFF)-based 3D printing is an efficient technique for developing medical implants, but it is not very useful in developing small yet mechanically robust design-specific fixtures such as dental implants (<15 mm). Specifically, it is challenging to 3D print robust Polyetheretherketone (PEEK) small implants due to PEEK's high melting temperature and melt viscosity. However, in this study, we efficiently utilize high-temperature FFF to develop the first-of-its-kind patient-specific robust PEEK dental implants with high print resolution. Specifically, we explore the effects of critical FFF processing conditions on the mechanical properties of the implants and subsequently determine an optimized set of processing conditions that are essential in developing durable dental implant systems. Our results indicate that the 3D printed dental implants exhibit good fatigue properties and suffice the clinical and industrial requirements for dental implants. Furthermore, we prove that the 3D printed implants exhibit adequate mechanical durability even after simulated (accelerated) aging of 30 years.
Subject(s)
Dental Implants , Ketones , Humans , Ether , Printing, Three-Dimensional , Ethyl Ethers , EthersABSTRACT
AIM: To investigate effect of body dimensions obtained from localizer radiograph and transverse abdominal computed tomography (CT) images on Size Specific Dose Estimate. METHODS: This study was approved by Institutional Review Board and was compliant with Health Insurance Portability and Accountability Act. Fifty patients with abdominal CT examinations (58 ± 13 years, Male:Female 28:22) were included in this study. Anterior-posterior (AP) and lateral (Lat) diameters were measured at 5 cm intervals from the CT exam localizer radiograph (simple X-ray image acquired for planning the CT exam before starting the scan) and transverse CT images. Average of measured AP and Lat diameters, as well as maximum, minimum and mid location AP and Lat were measured on both image sets. In addition, off centering of patients from the gantry iso-center was calculated from the localizers. Conversion factors from American Association of Physicists in Medicine (AAPM) report 204 were obtained for AP, Lat, AP + Lat, and effective diameter (â AP * Lat) to determine size specific dose estimate (SSDE) from the CT dose index volume (CTDIvol) recorded from the dose reports. Data were analyzed using SPSS v19. RESULTS: Total number of 5376 measurements was done. In some patients entire body circumference was not covered on either projection radiograph or transverse CT images; hence accurate measurement of AP and Lat diameters was not possible in 11% (278/2488) of locations. Forty one patients were off-centered with mean of 1.9 ± 1.8 cm (range: 0.4-7 cm). Conversion factors for attained diameters were not listed on AAPM look-up tables in 3% (80/2488) of measurements. SSDE values were significantly different compared to CTDIvol, ranging from 32% lower to 74% greater than CTDIvol. CONCLUSION: There is underestimation and overestimation of dose comparing SSDE values to CTDIvol. Localizer radiographs are associated with overestimation of patient size and therefore underestimation of SSDE.
