Bond strength enhancement for additively manufactured zirconia: Micro-retentive design approach.

Purpose: To investigate the effect of digitally designed micro-retention features on the bond strength of additively manufactured (AM) zirconia copings.

Materials And Methods: Sixty titanium base abutments (NobelParallel, NobelBiocare), pretreated with 50 µm alumina particles were divided into four groups (n = 15 per group); one group with subtractively manufactured zirconia copings (SM), and three test groups comprising one group with AM zirconia copings without any intaglio surface modification (AM-N), and two groups with digitally designed inverted pyramid-shaped micro-textures incorporated to the intaglio surface of the AM zirconia copings with two sizes: Ra 120 µm (AM-120) and Ra 240 µm (AM-240). All copings were bonded to the abutments using a conventional resin cement (Multilink Hybrid).

Effect of CAD-CAM tool deterioration on the trueness of ceramic restorations.

Statement Of Problem: Tools will gradually deteriorate with repetitive milling. However, tool lifetime can vary depending on the type of milling machine, the hardness of the ceramic material, and the size of the restoration. Studies evaluating the effect of tool deterioration on the trueness of milled restorations are lacking.

Effect of Milling Protocols on Trueness and Precision of Ceramic Crowns.

Purpose: To investigate the effect of different milling protocols for different ceramic materials on the trueness and precision of milled ceramic crowns.

Materials And Methods: A definitive impression from a patient requiring a ceramic crown was used to fabricate forty glass ceramic crowns (VITABLOCS mark II, Vita Zahnfabrik) milled with wet, hard milling protocol, and 40 zirconia crowns (inCoris TZI, Dentsply, Sirona) milled with dry, soft milling protocol, using a 5-axis milling machine (inLab MC X5; Dentsply Sirona). Trueness and precision for different crown areas were evaluated with a 3D evaluation software (Geomagic Control X, 3D systems).