Purpose: To compare the dimensions accuracy and surface roughness of polymeric dental bridges produced by different 3D printers. Design/methodology/approach: Four-part dental bridges were manufactured by three printing systems working on the basis of digital light projection (DLP) stereolithography (SLA), laser-assisted SLA and fused deposition modeling (FDM). The materials used from SLA printers are liquid methacrylate photopolymer resins, while FDM printer use thin wire plastic polylactic acid. The accuracy of the external dimensions of dental bridges was evaluated and the surface roughness was measured. Findings: It was found that compared to the base model, the dimensions of the SLA printed bridges are bigger with 1.25%-6.21%, while the corresponding dimensions of the samples, made by FDM are smaller by 1.07%-4.71%, regardless the position of the object towards the substrate. The samples, produced by FDM, are characterized with the highest roughness. The average roughness deviation (Ra) values for DLP SLA and lase-assisted SLA are 2.40 μm and 2.97 μm, respectively. Research limitations/implications: For production of high quality polymeric dental constructions next research should be targeted to investigation of the polymerization degree, stresses and deformations. Practical implications: Our study shows that 3D printers, based on laser-assisted and DLP SLA, can be successfully used for manufacturing of polymeric dental bridges – temporary restorations or cast patterns, while FDM system is more suitable for training models. The results will help the dentists to make right choice of the most suitable 3D printer. Originality/value: One of the largest fixed partial dentures – four-part bridges, produced by three different commercial 3D printing systems, were investigated by comparative analysis. The paper will attract readers’ interest in the field of biomedical materials and application of new technologies in dentistry.

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Purpose: of this paper is to investigate the accuracy of Co-Cr dental bridges, manufactured using 3D printed cast patterns. Design/methodology/approach: Four-unit dental bridges are fabricated from the alloys i-Alloy and Biosil-f by lost-wax process. The polymeric cast patterns are 3D printed with different layer’s thickness (13 μm, 35 μm and 50 μm). Two 3D printers are used: stereolithographic “Rapidshape D30” and ink-jet “Solidscape 66+”. The geometrical and fitting accuracy as well as the surface roughness are investigated. Findings: It is established that Co-Cr bridges, casted from 3D printed patterns with 50 μm layer thickness, characterize with the largest dimensions – 3.30%-9.14% larger than those of the base model. Decreasing the layer thickness leads to dimensional reduction. The dimensions of the bridges, casted on patterns with 13 μm layer thickness, are 0.17%-2.86% smaller compared to the primary model. The average roughness deviation Ra of the surface of Co-Cr bridges, manufactured using 3D printed patterns, is 3-4 times higher in comparison to the bridge-base model. The greater the layer thickness of the patterns, the higher Ra of the bridges. The silicone replica test shows 0.1-0.2 mm irregular gap between the bridge retainers and abutments of the cast patterns and Co-Cr bridges. Research limitations/implications: Highly precise prosthetic constructions, casted from 3D printed patterns, can be produced only if the specific features of the 3D printed objects are taken in consideration. Practical implications: Present research has shown that the lower the thickness of the printed layer of cast patterns, the higher the dimensional accuracy and the lower the surface roughness. Originality/value: The findings in this study will help specialist in dental clinics and laboratories to choose the right equipment and optimal technological regimes for production of cast patterns with high accuracy and low surface roughness for casting of precise dental constructions.

Digital technologies are evolving at a very high pace in science and technology. They are also increasing their influence in the fields of dental and general medicine. The processes are inevitable and irreversible. The advantage of these technologies is that they can create medical devices with a complex geometric shape, in a shorter time and with greater accuracy. The materials from which the sites are built go through constant development and improvement. In dental medicine, printing is expressed in the manufacture of prosthetic dental structures of removable and non-removable type, training models, production of artificial prostheses for the needs of oral and maxillofacial surgery. In the field of otorhinolaryngology, 3D printing is used for the production of ectoprostheses in the removal of various inflammatory and tumor processes of the nose and ears, or as a result of occupational or traffic accidents. Printing also finds a place in ophthalmology for making eye prostheses. Regardless of the field of application, these technologies pose a challenge in their use in everyday clinical practice and are subject to constant monitoring by physicians and patients. Objective: To study the application of 3D printing in the head and in particular in otorhinolaryngology.

Purpose: of the present paper is to offer treatment protocol with fixed partial dentures, produced by selective laser melting, including clinical and laboratory parts. Design/methodology/approach: The treatment protocols with selective laser melted fixed partial dentures was developed on the basis of literature survey and our previous research about accuracy and mechanical properties of dental bridges, manufactured by additive technologies. Findings: The treatment protocol with fixed partial dentures, produced by selective laser melting, consisting of clinical and laboratory parts, was developed. The treatment procedures with FPD made by SLM were classified as semi-digital when working with extraoral scanner and fully-digital – with intraoral scanner. Research limitations/implications: The introduction of the proposed treatment protocol into the clinical and laboratory practice would lead to a systematic approach and working optimization for prosthodontists and dental technicians when using selective laser melting. Practical implications: Due to the elimination of multiple manual manipulations and technological operations, treatment protocols with FPD, produced by SLM, ensure higher accuracy and quality of the constructions and shorter time for their manufacturing compared to the conventional procedure. Originality/value: The developed clinical and laboratory protocols for the treatment and manufacturing of FPD through SLM clearly show the benefits of the new technology in dentistry and dental technician field.