## 5 Discussion
Nevertheless, these discs are liable to get displaced during function and might wear out resulting in aseptic joint loosening [21; 24]. Although no interposition disc was used during biomechanical testing in this study, it would be an exciting possibility to evaluate, in the future, anatomically designed 3D alloplastic TMJ condyle, glenoid fossa, and articulating disc. While the novel aspect of the present study was the anatomic precision of alloplastic TMJ parts digitally custom-designed using 3D mirroring techniques, the most critical aspect was the evaluation of mechanical performance of different biomaterials against each other during function. With the help  
\begin{table} \begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Mechanical Properties**} & \multicolumn{4}{c}{**Biomaterial**} & \multirow{2}{*}{**Mature Cortical**} \\ \cline{2-2} \cline{4-5}  & **EBM Titanium** & & & **Zirconia (ZrO2)** & **Acrylic (PMMA)** \\ \hline
**Compressive Strength** & & & & \\
**(MPa)** & 940–970 & 1200–5200 & 105–117 & 100–230 \\
**Tensile Strength** & 880–950 & 115–711 & 62–75 & 50–151 \\
**Elastic Modulus** (_GPa_) & 113.8–334.2 & 100–250 & 2.45-3.12 & 7–30 \\
**Hardness** (_GPa_) & 1.125–2.18 & 5.5–15.75 & 0.66–0.69 & 0.41–0.89 \\ \hline \hline \end{tabular} 
\begin{tabular}{c} EBM—of digital modelling and CAD, it was possible to generate a 3D model of the TMJ to be replaced and reconstructed, and the same was used for digital manufacturing of condyle and glenoid fossa parts using different EBM-Ti, zirconia, and acrylic. This aspect of the present study is in coherence with several previous studies, which have documented the precision and accuracy achievable through 3D rapid prototyping and CAD/CAM technologies [16; 19; 20; 23; 39]. Nevertheless, particulate wear is a major adverse effect associated with alloplastic prosthetic joints irrespective of the biomaterial used or of their mechanical properties [40]. This in-turn contributes to peri-prosthetic foreign body reaction, inflammation, and aseptic loosening of the prosthetic components [21; 24; 40]. The preliminary results of the present study subscribe to the above-mentioned fact, in spite of the custom fabricated alloplastic TMJ design. The results of the present study provide evidence favoring the biomechanical stability of custom fabricated alloplastic TMJ, with anatomically mirrored condyle and glenoid fossa parts. This is in coherence with a recent review about the biomechanical properties of different total TMJ replacement systems evaluated through finite-element analysis, and reported lower stress values for customized TMJ components [41]. Furthermore, anatomically mirrored prosthetic condyle and glenoid fossa elements enables their close approximation to the native bone and could facilitate enhanced osseointegration [8]. However, the present outcomes must be considered in light of the following limitations. This study provides information pertaining to preliminary biomechanical evaluation only and the simulation testing while replicating compression and translation movements accurately, could not perfectly replicate rotational movements. Moreover, the 3D CAD/CAM protocol used for fabrication and subsequent biomechanical simulation testing, considered replacement of unilateral alloplastic TMJ parts only.