(1) Background: Stereophotogrammetry has recently been investigated showing high accuracy in complete implant supported cases but has scarcely been investigated in cases of tilted implants. The aim of this in vitro study was to compare the accuracy of digital impression techniques (intraoral scanning and photogrammetry) at the level of intraoral scan bodies in terms of angular deviations and 3D discrepancies. (2) Methods: A stone master cast representing an edentulous maxilla using four implant analogs was fabricated. The two anterior implants were parallel to each other, and the two posterior implants were at an angulation of 17 degrees. Digital intraoral scanning (DIOS) impressions were taken after connecting implant level scan bodies to the master cast and STL files were exported (n = 15). Digital photogrammetry (DPG) impressions were captured using a PiC Camera after tightening implant level PiC optical markers and STL files were exported (n = 15). Superimposition was carried out by a software for determining the accuracy of both. (3) Results: Significant angular discrepancies (ΔA) and 3D deviations of scan bodies were found among the groups in trueness with lower deviations for the DPG (p value < 0.001). However, trueness within ISBs varied between angular and 3D deviations and outcomes were not specific to determine the effect of implant angulation. In precision, no significant differences were detected within ISBs and among both groups in terms of angular deviation. However, DPG had less deviations than DIOS group in terms of 3D deviations (p value < 0.001). (4) Conclusion: Digital photogrammetry technique conveyed the utmost accuracy in both trueness and precision for the intraoral scan bodies among both impression methods assessed. In addition, implant angulation did not influence the precision of the impression techniques but affected their trueness without explicit conclusions.

To evaluate and compare the surface morphology, wettability, roughness, and bacterial adhesion properties of polymethyl methacrylate (PMMA) materials fabricated by conventional methods and 3D printing for complete denture applications. Two PMMA materials were investigated: Conventionally processed (ProBase Hot) and 3D-printed (3DP) (V-Print Dentbase). Surface morphology (n = 3) was analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Surface roughness (n = 10) was measured using an optical profilometer. Wettability was assessed through contact angle measurements (n = 6) at 10, 30, and 60 seconds. Bacterial adhesion (n = 9) and biofilm formation (n = 3) were evaluated using Escherichia coli (E. coli) as a model organism, with quantitative bacterial counts and SEM analysis of bacterial morphology. Data were statistically analyzed. Scanning electron microscopy analysis revealed nanoparticles on the surface of 3DP samples, while EDX detected silicon in these samples, absent in conventional PMMA. 3D-printed surfaces exhibited significantly lower roughness (1.05 ± 0.32 µm) compared to conventional surfaces (20.46 ± 6.71 µm) (p < 0.001). Contact angle measurements showed that 3DP surfaces were more hydrophilic (64-68°) than conventional surfaces (100°) (p < 0.05). Bacterial adhesion studies demonstrated more adherent bacteria on 3DP surfaces (92.5 ± 30.8) compared to the conventional surfaces (57.6 ± 12.5), but biofilm formation was observed only on conventional surfaces. 3D-printed PMMA exhibited distinct surface characteristics compared to conventionally processed PMMA, including the presence of silicon nanoparticles, lower surface roughness, and higher hydrophilicity. While 3DP surfaces showed higher initial bacterial adherence, in contrast, they appeared to inhibit biofilm formation, which highlights the complex nature of bacterial interactions with these materials. Further clinical studies are needed to validate the results of this investigation and generate clinical translational data. How to cite this article: Khoury P, Kharouf N, Etienne O, et al. Physicochemical Properties and Bacterial Adhesion of Conventional and 3D Printed Complete Denture PMMA Materials: An In Vitro Study - Part I. J Contemp Dent Pract 2024;25(11):1001-1008.

The objective of this study was to assess the effect of stacking on the dimensional and full-arch accuracy of 3D-printed models, utilising a standardised assessment methodology. A previously validated methodology involving a standard tessellation language image (STL) reference model, comprising seven spheres on a horseshoe base resembling a dental arch, was used. Six 3D-designed STL models were prepared, optimised, and stacked horizontally using 3D Sprint software. The stacking file was transferred to the NextDent 5100 printer to build the physical models. To assess accuracy, a coordinate measuring machine (CMM) measured the diameter of the spheres $\left(n=210\right)$, and twenty-one vectors extended between the centres of each of the seven spheres (n = 630). When compared to the reference model, significant differences were observed for dimensional (p = 0.006) and full-arch accuracy (p = 0.006) for all stacked models. Additionally, significant differences were observed between the stacked models for the dimensional accuracy between the posterior (p = 0.015), left posterior (p = 0.005) and anteroposterior (p = 0.002). The maximum contraction was observed in the fourth stacked model, which demonstrated the highest median deviation and least precision within the full-arch (MD = 666 μm, IQR = 55 μm), left posterior (MD = 136 μm, IQR = 12 μm), posterior (MD = 177 μm, IQR = 14 μm) and anteroposterior (MD = 179 μm, IQR = 16 μm) arch segments. In general, the anterior and left posterior arch segments recorded the highest contractions with a median deviation of 34 μm and 29 μm, and precision of 32 μm and 22 μm, respectively. Statistically significant differences were observed between the stacked models in terms of dimensional accuracy that were within clinically acceptable thresholds. The greatest contraction was noted in the fourth model, displaying the least full-arch accuracy compared to the other models. Stacked, additively manufactured, full arch models are a viable alternative for diagnostic, orthodontic, and single-unit prosthodontic applications. In contrast, caution should be exercised when utilising stacked models for full arch high accuracy prosthodontic applications. Further research is needed to assess the impact of additional variables including different printers and resins.