A discussion of “In vitro analysis of shear stress: CAD milled vs printed denture base resins with bonded denture tooth”

Abstract

Dear EditorWe reviewed the article "In vitro analysis of shear stress: CAD milled vs printed denture base resins with bonded denture tooth" 1 with great interest and congratulate the authors on the publication. However, we believe certain parts of the protocol deserve further discussion. More specifically, our concern is about how the authors bonded the teeth to the denture bases fabricated from Lucitone Digital Print™ 3D Denture Base resin (LDP). In short, we believe the failure to follow the validated workflow outlined in LDP's Instructions for Use (IFU) impacted the authors' results.The researchers used IvoBase ® CAD Bond (Ivoclar Vivadent AG, Schaan, Liechtenstein) to bond VITA VITA-PAN EXCELL T44, #8 denture teeth (VITA Zahnfabrik, Bad Säckingen, Germany) to denture bases fabricated from different materials and techniques (Lucitone 199 ® Denture Base Resin (Dentsply Sirona, York, PA) -heat-polymerized; IvoBase ® CAD (Ivoclar Vivadent AG, Schaan, Liechtenstein) and PoliDent PMMA CAD/CAM disc (PoliDent, Draga, Slovenia) -milled; and Formlabs Denture Base Resin (DENTCA, Inc. Torrance, CA) and LDP (Dentsply Sirona, York, PA) -3D-printed). The specimens were artificially aged in distilled water and statically loaded to failure using a universal testing machine (Instron, Norwood, MA). Shear bond strength (SBS) and mode of failure (MoF) were the outcomes assessed. 1 Their results showed LDP's SBS to be statistically lower than that of the other four materials tested, and 100% of fractures (of all materials) to be both adhesive and cohesive. 1 The latter is in stark contrast to Dentsply Sirona's (DS) internal tests and to Alfadhli's findings, with both showing all fractures to be cohesive. 2 Alfadhli goes even further to show that, of all denture base materials tested (very much the same as Kane and Shah, 1 with the exception of PoliDent, as detailed below), LDP was the only one to present 100% of cohesive fractures with and without thermocycling. Still according to the author, LDP showed the highest SBS of all test materials in both test scenarios. These conflicting results can be explained by differences in sample preparation and testing methods.Contrary to the work of Kane and Shah 1 DS internal tests were conducted following the validated workflow outlined in LDP's IFU. 3 As LDP contains no methyl methacrylate, teethThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.