Table 8.

Microhardness Test Results.

Author and Year	Mean Microhardness for Conventional Resin (Kgf/mm2/KHN)	Mean Microhardness for CAD/CAM Milled Resin (Kgf/mm2/KHN)	Mean Microhardness for 3D-Printed Resin (Kgf/mm2/KHN)	Surface Treatment/Exposure Agent/Ageing Technique	Testing Machine Used	Authors Suggestions/Conclusions
Simoneti et al., 2022 [53]	Vickers microhardness (A) Acrylic resin: 14.2 ± 2.6 Kgf/mm2 (B) Bis-acryl resin: 10.7 ± 2.2 Kgf/mm2	NA	Vickers microhardness (C) SLA resin 8.4 ± 0.2 Kgf/mm2 (D) SLS resin 10.3 ± 1.0 Kgf/mm2	Polished specimens	Microdurometer (FM-700; Future-Tech Corp.).	Microhardness: Conventional Acrylics > Conventional Bisacrylic > 3D-printed PMMA > 3D-printed methacrylates
Revilla-León et al., 2021 [49]	Knoop hardness (A) Protemp 4: 4.92 ± 0.36 KHN (B) Anaxdent new outline dentin: 13.35 ± 5.84	N/A	Knoop hardness (C) FreePrint temp: 12.55 ± 2.93 KHN(D) E-Dent 400 C&B MFH: 13.03 ± 3.29 KHN (E) NextDent C&B MFH: 9.91 ± 3.71 (F) Med620 VEROGlaze: 13.45 ± 2.93	N/M	Microhardness tester (MMT-X7, Matsuzawa)	Knoop hardness: 3D-Printed (group (F) > Conventional PMMA (group (B) > 3D-printed acrylic esters (group (D) > 3D-Printed MMA (group (C) > 3D-Printed PMMA (group (E) > Conventional bisacrylic (group A) 3D-Printed materials have suitable MP to be used as provisional restorations.
Digholkar et al., 2016 [33]	Knoop hardness (A) heat activated PMMA: 27.36 ± 0.535 KHN	Knoop hardness (B) Ceramill TEMP: 25.33 ± 0.900 KHN	Knoop hardness (C) E-Dent 100: 32.77 ± 1.361 KHN	N/M	Microhardness tester (Reichert Austria)	3D-printed Microhybrid filled composite >Conventional heat activated PMMA >CAD/CAM milled PMMA
Crenn et al., 2022 [29]	Vickers Microhardness (A) Integrity: 27.3 ± 1.8 HV (B) Unifast: 18.4 ± 1.2 HV	N/A	Vickers Microhardness (C) PLA Bio source: 17.5 ± 0.7 HV (D) Temporary CB: 28.9 ± 2.9 HV	Polished specimens	Vickers Microhardness tester (MH3, Mekton, Turkey)	3D-printed SLA > Conventional Bisacrylic > conventional Methylmethacrylate > 3D-Printed FDM

N/A: Not Applicable; SLA, stereo lithography; SLS, selective laser sintering; N/M: Not Mentioned.