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AIM The objective of this systematic review was to evaluate the efficacy of denture adhesives (DAs) in completely edentulous denture wearers compared to not using DAs. METHODS AND RESULTS PubMed, Web of Science, Cochrane Library, and EMBASE were searched from the database inception up to 6 February 2020 for Randomized Controlled Trials (RCTs) involving patients with complete dentures in both arches where the use of DAs was compared to no use of DAs. A total of 497 abstracts were reviewed, resulting in inclusion of 10 RCTs. Outcomes reported in the included trials were thoroughly reviewed and tabulated. The Cochrane risk of bias tool was used. All 10 studies were assessed at unclear (10%) or high risk of bias (90%). Studies showed DAs improved mainly retention/stability, and masticatory/chewing ability/performance, compared to no adhesives. CONCLUSION Most studies showed favorable results for DAs on retention and stability of complete dentures, masticatory performance, patient's comfort and satisfaction. Due to the heterogeneity of the outcomes, unclear/high risk of bias and small sample sizes, the quality of the evidence was very low. More high-quality research is needed with improved blinding and use of standardized methods to evaluate the efficacy of DAs.

Electron beam melting (EBM) additive manufacturing (AM) technology has allowed the layerwise fabrication of parts from metal powder precursor materials that are selectively melted using an electron beam. An advantage of EBM technology over conventional manufacturing processes has been the capability to change processing variables (e.g., beam current, beam speed, and beam focus) throughout part fabrication, enabling the processing of a wide variety of materials. In this research, additional scans were implemented in an attempt to promote grain coarsening through the added thermal energy. It is hypothesized that the additional energy caused coarsening of Ti-6Al-4V microstructure that has been shown to increase mechanical properties of as-fabricated parts as well as improve surface characteristics (e.g., reduced porosity). Fatigue testing was performed on an L-bracket using a loading configuration designed to cause failure at the corner (i.e., intersection of the two members) of the bracket. Results showed 22% fatigue life improvement from L-brackets with as-fabricated conditions to L-brackets with a graded microstructure resulting from the selective addition of thermal energy in the expected failure region. Three L-brackets were fabricated and exposed to a triple melt cycle (compared to the standard single melt cycle) during fabrication, machined to specific dimensions, and tested. Results for fatigue performance were within ∼1% of wrought L-brackets. The work from this research shows that new design procedures can be implemented for AM technologies that involve evaluation of stress concentration sites using finite element analysis and implementation of scanning strategies during fabrication that help improve performance by spatially adjusting thermal energy at potential failure sites or high stress regions.

Quality assurance is an important topic for additive manufacturing (AM) and often seen as a requirement for the transition and adoption of the technology toward fabrication of end use applications. As AM technologies are used for production, it is necessary to ensure high quality, repeatable, and reproducible components are manufactured. Various nondestructive examination techniques have been used to evaluate AM-fabricated parts to determine part quality post-fabrication (e.g. scanning and/or microstructural characterization). In situ monitoring methods have been developed for AM technologies to enable defect detection and have potential to be used for in situ monitoring and correction of fabrication anomalies (e.g. undesired temperature gradients and porosity). In this research, defects (e.g. pores) were seeded into parts fabricated using the powder bed fusion AM process, electron beam melting, and monitored using in situ infrared (IR) thermography. Results from layerwise thermography were compared with results obtained using computer tomography (CT) scanning techniques. Although the measured geometry of the seeded defects between IR thermography and CT was substantially different (area difference of ~60%), the thermographs did provide a good indication of defects present within a fabricated part. Furthermore, defect correction methods were evaluated including post-processing methods such as hot isostatic pressing as well as in situ correction methods such as layer re-melting. Re-melting a porous layer successfully corrected defects and demonstrates a potential method for in situ defect correction if implemented in future systems equipped with automatic feedback control of powder bed fusion processes.

We describe our efforts to use source-level rewriting to optimize run-time program generators written in Jumbo, a run-time program generation system for Java. Jumbo is a compiler written in compositional style, which brings the advantage that any program fragment can be abstracted out and compiled to an intermediate form. These forms can be put together at run-time to build complete programs. This principle provides a high level of flexibility in writing program generators. However, this comes at the price of inefficient run-time compilation. Using source-level transformations, we optimize the run-time generation of byte code from fragments, achieving speedups of 5–15%. We discuss the optimization process and give several examples.