Removable partial dentures may offer an attractive treatment option for an edentulous patient, as they may combine an FPD in the anterior segment with a removable appliance in the posterior areas. A satisfying restoration can be achieved with fewer implants.

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Aim: The precise framework fit is important for the success of implant restorations. The purpose of the present study was to examine the effect of two different impression materials both of their medium viscosity on the master cast accuracy when parallel and inclined implants were used. Materials and Methods: An epoxy master cast with three implants was fabricated. The first two implants were parallel to each other and perpendicular to the horizontal plane and the third implant had a 250 inclination in reference to the other two. A passively fitting metal framework that was fabricated over this master cast was used to measure accuracy of fit. Five closed tray impressions for each medium viscosity material (polyether and polyvinyl-siloxane) tested were taken and the respective ten stone casts with three implant analogs were fabricated. The metal framework in the master cast, was fixed in the new specimens and the micro-gap between this prosthesis and the implant analogs was evaluated. The specimens were observed to an optical microscope and digital photography. Results and Conclusion: The data were statistically analysed using a computer software and t-test. Polyether exhibited higher micro-gap mean values (93,4 to 61,8 μm) compared to polyvynil siloxane (30,47 to 14,83μm). The differences were statistically significant only for implant B. The categorical regression analysis (p < 0.01) for all implants showed that the marginal micro-gap was affected by the impression material (94.1%) and significantly by the type of it. The micro-gap values were higher for polyether compared to polyvinyl-siloxane. The torqued implant did not exhibit any statistically significant effect.

Background: One type of failure in complete or partial dentures is the detachment of resin teeth from denture base resin (DBR). This common complication is also observed in the new generation of digitally fabricated dentures. The purpose of this review was to provide an update on the adhesion of artificial teeth to denture resin substrates fabricated by conventional and digital methods. Methods: A search strategy was applied to retrieve relevant studies in PubMed and Scopus. Results: Chemical (monomers, ethyl acetone, conditioning liquids, adhesive agents, etc.) and mechanical (grinding, laser, sandblasting, etc.) treatments are commonly used by technicians to improve denture teeth retention with controversial benefits. Better performance in conventional dentures is realized for certain combinations of DBR materials and denture teeth after mechanical or chemical treatment. Conclusions: The incompatibility of certain materials and lack of copolymerization are the main reasons for failure. Due to the emerging field of new techniques for denture fabrication, different materials have been developed, and further research is needed to elaborate the best combination of teeth and DBRs. Lower bond strength and suboptimal failure modes have been related to 3D-printed combinations of teeth and DBRs, while milled and conventional combinations seem to be a safer choice until further improvements in printing technologies are developed.

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