## 3 Results
### Main Characteristics of the Studies Included in the Systematic Review  
This systematic review includes articles on dental materials fabricated with CAD-CAM whose mechanical and biological properties were possibly modified by the incorporation of composite materials. Thus, 8 articles were analyzed in which the materials were printed using the additive SLA technique, 2 articles referred to fabrication by milling, 8 articles to DLP printing, and 1 article to daylight polymer printing (DPP).  
The different compounds incorporated into the CAD-CAM-fabricated dental materials were zirconia nanoparticles (ZrO\({}_{2}\) NPs) [13; 30; 31], graphene [25], graphene oxide [32], graphene nanoplatelets (GNPs) [14; 33], silver-reinforced mesoporous silica nanoparticles (Ag-MSN) [15], aluminum nitride [34], bioactive glasses [35], ceramic nitrides [18], zwitterionic particles [19], nanodiamonds [36], aminated nanodiamonds (A-ND) [37], titanium dioxide (TiO\({}_{2}\)) nanoparticles [16; 38; 39; 40], and silver-reinforced cellulose nanocrystals (Ag-CNCs) [17].  
Figure 1: PRISMA-FLOW diagram used for the bibliographic search.  
Another piece of information described in most studies is related to the size and distribution of the particles incorporated in the materials. The distribution is often referred to as uniform in the resin matrix [15; 31] or forms regular agglomerates [17; 37; 38; 40]. Particle size varied from 4-6 nm of aminated nanodiamonds [37] to 56-170 nm for TiO\({}_{2}\) nanoparticles [40] and 100-150 nm for ZrO\({}_{2}\) NPs [31] (Table 1).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Study**} & \multicolumn{2}{c}{**Chemical Composition**} & \multirow{2}{*}{**Manufacture**} & \multirow{2}{*}{**Manufacturing Technique**} & \multirow{2}{*}{**Distribution and Size of Particles**} & \multirow{2}{*}{**Quality Assessment Score**} \\ \cline{2-2} \cline{6-6}  & **Resin** & **Compound** & & & & \\ \hline [PERSON] et al., 2021 [18] & PMMA-based resin & \multirow{2}{*}{Ceramic nitrides} & Clear & & & \\  & & & photoreactive resin, Formlabs, & & & \\  & & & USA & & & \\ \hline [PERSON] et al., 2021 [19] & PMMA-based resin & \multirow{2}{*}{Zwitterionic materials} & Orthorigid, & & & \\  & & & NextDent BV, The Netherlands & & & \\ \hline [PERSON] et al., 2020 [36] & PMMA-based resin & \multirow{2}{*}{Nanodiamonds} & Orthorigid, & & & \\  & & & NextDent BV, The Netherlands & & & \\ \hline [PERSON] et al., 2020 [37] & PMMA-based resin & \multirow{2}{*}{Animated nanodiamonds} & Orthorigid, & & & \\  & & & NextDent BV, The Netherlands & & & \\ \hline [PERSON] et al., 2020 [37] & PMMA-based resin & \multirow{2}{*}{Ansonidamonds} & Orthorigid, & & & \\  & & & NextDent BV, The Netherlands & & & \\ \hline [PERSON] et al., 2020 [38] & \multirow{2}{*}{Urethane-acrylate resin} & Silver-reinforced titanium dioxide nanoparticles (Ag-TNF) 1%, 1.2\% & Resin based on urethane-acrylate (Sartomer America, Exton, PA, USA) & & & Titanium dioxide = 30–40 nm; silver nanoparticles = 5–10 nm & 7 average \\ \hline [PERSON] et al., 2019 [26] & PMMA & Graphene & PMMA, Zotion, & & & \\  & & Graphene & Chongqing, & & & \\  & & & China & & & \\ \hline [PERSON] et al., 2019 [16] & PMMA-based resin & \multirow{2}{*}{Triamu dioxide (TIO\({}_{2}\))-polyetherether ketone (PEEK) nanoparticles TiO\({}_{2}\)-1%-PEEK-1%-PEEK-1%-PEEK-2%} & \multirow{2}{*}{Orthorigid, & & & \\  & & & NextDent BV, The Netherlands & & & \\  & & & & & \\ \[PERSON] et al., 2018 [17] & PMMA-based resin & \multirow{2}{*}{Titanium dioxide (TIO\({}_{2}\))} & \multirow{2}{*}{E-Denture, } & & & \\  & & & nextDent, & & & \\  & & & nextDent, & & & \\  & & & nextDent, & & \\  & & & nextDent, & & \\  & & & nextDent, & & \\ \[PERSON] et al., 2018 [39] & PMMA-based resin & \multirow{2}{*}{Triamu dioxide (TIO\({}_{2}\))} & E-Dent