We extracted publication counts based on substances related to 3D printing in medical applications, as shown in Figure . Polycaprolactone, poly(lactic acid), and alginic acid are the top three commonly used 3D printing biomaterials for medical implants, bone/cartilage repair, and dental materials. Under the polymer category (Figure ), polycaprolactone, poly(lactic acid), and polyethylene glycol are the first three polymers with the higher number of publications. Majority of these polymers are used in tissue engineering cartilage and bone, or in constructing medical implants. We also searched the unspecified substances, "gelatins, collagens, fibroin, fibrins and their derivatives" in our database. Gelatins and collagens are the two major natural polymers applied as hydrogels in various fields across different 3D printing techniques. In Figure , hydroxylapatite (HAp, Ca5(PO4)3(OH))-related publications are the highest among the top 15 inorganic substances for dental materials and bone repair. Tricalcium phosphate (TCP) is another major inorganic material with myriads of inventions in bone repair/regeneration. HAp and TCP are both capable of forming hybrid polymers with other natural/synthetic polymers for bone tissue engineering. This enhanced their development in journals over patent publications. Titanium/Ti6Al4V are mainly featured as the materials for bone implants/repairs using 3D printing techniques. The journal/patent publication differences are insignificant for titanium containing materials except Ti6Al4V. For Ti6Al4V alloy, we are expecting more patents to be granted in the foreseeable future. For the extrusion-based technique (Figure ), synthetic polymers like poly(lactic acid) and polycaprolactone are the major substances involved in this technique, as well as natural polymers like alginic acid and its sodium salts. Gelatins and collagens (which exist in CAS database as unspecified substances), are also widely used in extrusion-based 3D printing. Polyethylene glycol diacrylate (PEGDA) and HAp powders form composites via photopolymerization 3D printing and are the top two substances occurring in photopolymerization-related documents (Figure ). Acrylic monomers like methacrylic acid and acrylic acid, as well as photoinitiators, for instance, bis(2,4,6trimethylbenzoyl)phenylphosphine oxide, led to high patent numbers because they are commonly used as the starting materials for synthetic hydrogels. Alginic acid, hyaluronic acid, sodium alginate, and chitosan are the major natural hydrogels used as feeding materials for 3D printing. Polyethylene glycol and polyethylene glycol diacrylate are the two major synthetic hydrogels. Gelatins and collagens are the two unspecified substances that contributed the most as hydrogels to biomedical 3D printing. This trend is similar to those in Figure . This is not surprising considering that hydrogels are the most widely used materials for 3D bioprinting. Figure shows that gelatins, collagens, and their derivatives result in significant numbers of publications in both journals and patents. Alginic acid is focused by people for journal publications, and hyaluronic acid is reported by more researchers as patents instead. In 2021, the number of patent publications in several polymers decreased. This may have resulted from the progress of patent issuing in 2021. Figure indicates that HAp is leading the inorganic substance as 3D printing material in biomedical applications. The trend between journals and patents (the number of journals is higher than patents) displays that HAp has been investigated and has the potential to be commercialized in the foreseeable future. Titanium, TCP, and Ti6Al4V also have steady development, but Ti6Al4V still has relatively lower patent publication counts than other substances. We can look forward to seeing the rapid patent growth in Ti6Al4V as a 3D printing material. The decline of patent publication count in 2021 may be related to the progress of patent issuing.