The "Workshop on Standards & Measurements for Tissue Engineering Scaffolds" was held on May 21, 2013 in Indianapolis, IN, and was sponsored by the ASTM International (ASTM). The purpose of the workshop was to identify the highest priority items for future standards work for scaffolds used in the development and manufacture of tissue engineered medical products (TEMPs). Eighteen speakers and 78 attendees met to assess current scaffold standards and to prioritize needs for future standards. A key finding was that the ASTM TEMPs subcommittees (F04.41-46) have many active "guide" documents for educational purposes, but few standard "test methods" or "practices." Overwhelmingly, the most clearly identified need was standards for measuring the structure of scaffolds, followed by standards for biological characterization, including in vitro testing, animal models and cell-material interactions. The third most pressing need was to develop standards for assessing the mechanical properties of scaffolds. Additional needs included standards for assessing scaffold degradation, clinical outcomes with scaffolds, effects of sterilization on scaffolds, scaffold composition, and drug release from scaffolds. Discussions highlighted the need for additional scaffold reference materials and the need to use them for measurement traceability. Workshop participants emphasized the need to promote the use of standards in scaffold fabrication, characterization, and commercialization. Finally, participants noted that standards would be more broadly accepted if their impact in the TEMPs community could be quantified. Many scaffold standard needs have been identified and focus is turning to generating these standards to support the use of scaffolds in TEMPs.

In consultation with ASTM and other stakeholders in Tissue-Engineered Medical Products (TEMPs) industry, the National Institute of Standards and Technology (NIST) initiated a project designed to produce Reference Material scaffolds for tissue engineering. The rationale for Reference Material scaffolds was developed through several NIST/Industry workshops. In brief, Reference Material scaffolds have multiple uses: facilitating the development and the validation of new test methods that measure interactions among various components of a TEMP; comparison with other scaffolds and scaffold materials in terms of cellular responses, biodegradation, and releases of growth factors; and comparisons of responses among various cell lines. The primary customers for Reference Material scaffolds are expected to be the TEMPs industry, academic researchers, regulators, and standards developing organizations. There are many properties of a TEMP that warrant development of multiple Reference Material scaffolds. Currently, NIST is defining a set of Reference Material scaffolds based on geometric descriptors such as permeability, pore volume, pore size distribution, interconnectivity, and tortuosity. In consultation with ASTM, NIST is testing three candidate scaffolds produced by: three dimensional (3-D) printing, stereolithography, and fused deposition modeling (FDM). Scaffolds made by these methods have been obtained from Mayo Clinic (Rochester, MN), Case Western Reserve University (CWRU) (Cleveland, OH), and Osteopore International (Singapore), respectively, for structural characterization. These prototype scaffolds, with well-defined architectures, have been selected to address the following items of interest: 1) establishment of useful functional definitions of porosity content, interconnectivity, and pores; 2) evaluation of testing methods listed in the Standard Guide for the Porosity of Polymeric Scaffolds for Use in Tissue-Engineered Medical Products, which is being drafted by ASTM. Currently, NIST and the Center for Devices and Radiological Health of the Food and Drug Administration, as well as other groups from US and foreign laboratories, are actively carrying out cross-validation test of these prototype scaffolds.

Three-dimensional (3D) microprinting is a computerized fabrication technique that can produce porous objects with highly complicated pore micro-architecture using data generated by computer aided design (CAD) or other imaging modalities [1]. This technique has been used for fabrication of porous biodegradable polymeric scaffolds that are intended, by design, to have reproducible and well-defined pores and connections for skeletal tissue engineering applications [2-4]. Scaffold porosity and interconnectivity are important design variables for tissue regeneration [5,6]. One measure related to pore interconnectivity is hydraulic permeability, the flow velocity through a porous material at a fixed pressure gradient [7]. The objective of this work was to study the effect of pore size and interconnectivity (defined as the fraction of cubic empty spaces connected to the outside air) on hydraulic permeability of polymeric scaffolds with well design-defined interconnectivity and pore micro-architecture.

Dental materials are those materials used to provide therapy for the hard and soft oral tissues. This therapy includes the replacement of oral tissues lost through disease with inert materials, ie, metallic, ceramic, and organic, or with composites employing combinations of these three broad classes. The operative restorations and prostheses are made of amalgam, precious and nonprecious alloys, special cements, synthetic polymers, porcelain, and glass‐ceramics, all of which must withstand the rigors of the oral environment (see also Prosthetic and Biomedical Devices). The accessory materials needed in the fabrication procedures include synthetic polymers, synthetic and natural gums and waxes, hydrocolloids, gypsums, and refractories. These materials are used by ca 170,000 practicing dentists in the United States (1992) and more than 8,500 commercial U.S. dental laboratories employing ca 40,000–50,000 technicians.

Cooperation is one avenue being pursued among American industry, labor, and government to ensure a strong internationally competitive U.S. economy. At the National Bureau of Standards (NBS), we have a program which facilitates cooperative interaction. This article focusses on one of our longest running cooperative projects, dental materials research.