The Effect of Incorporating Dimethylaminohexadecyl Methacrylate and/or 2-Methacryloyloxyethyl Phosphorylcholine on Flexural Strength and Surface Hardness of Heat Polymerized and 3D-Printed Denture Base Materials

Abstract

Background: A major disadvantage of polymethyl methacrylate (PMMA) acrylic resins is susceptibility to biofilm accumulation. The incorporation of antimicrobial agents is a reliable prevention technique. The purpose of this study is to investigate the effect of incorporating dimethylaminohexadecyl methacrylate (DMAHDM) and/or 2-methacryloyloxyethyl phosphorylcholine (MPC) into heat-polymerized (HP) and 3D-printed (3DP) denture base materials on the flexural strength, modulus of elasticity, and surface hardness.

Methods: DMAHDM and/or MPC were mixed with the acrylic resin liquid of a heat-polymerized (ProBase Hot) and a 3D printed (NextDent Denture 3D) material at mass fractions of 1.5% and 3% and a combination of 3% MPC and 1.5% DMAHDM.

Results: Significant differences in mechanical properties between the control and experimental groups have been detected (p-value < 0.0001). In HP materials, the addition of DMAHDM and/or MPC generally decreased the flexural strength, from (151.18 MPa) in G1 down to (62.67 MPa) in G5, and surface hardness, from (18.05 N/mm²) down to (10.07 N/mm²) in G5. Conversely, in 3DP materials, flexural strength was slightly enhanced, from (58.22 MPa) in G1 up to (62.76 MPa) in G6, although surface hardness was consistently reduced, from (13.57 N/mm²) down to (5.29 N/mm²) in G5.

Conclusion: It is recommended to carefully optimize the concentrations of DMAHDM and/or MPC to maintain mechanical integrity.

Keywords: antifungal; candida albicans; denture base material; denture stomatitis; flexural strength; removable dentures; surface hardness.

Figure 1

The structure of DMAHDM shows a chain length of 16 units.

Figure 2

Graphical presentation of the specimens’ formulation procedure.

Figure 3

Rectangular specimens design measuring 65 × 10 × 3.3 mm (±0.2 mm).

Figure 4

Specimen fixed on the INSTRON machine, where the middle of the specimen is marked by a black line to ensure proper placement.

Figure 5

A square-based pyramid diamond indenter performing the Vickers hardness test on the rectangular specimen.

Figure 6

Comparison of the mean flexural strength values between the six study groups in each of the tested materials (HP, 3DP). A highly statistically significant difference is detected among the six groups of the two study materials, and a notable superiority of the HP material is noticed.

Figure 7

Comparison of mean flexural strength differences between the six study groups between the two tested materials. Displaying significant differences among all groups except G5. Significant comparisons are marked with a red star (* = p = value ≤ 0.05).

Figure 8

Comparison of the mean elastic modulus values between the six study groups in each of the tested materials (HP, 3DP). A highly statistically significant difference is detected among the six groups of the two study materials, showing a noticeable superiority of the HP material over the 3DP.

Figure 9

Comparison of mean elastic modulus differences between the six study groups between the two tested materials. Displaying significant differences among all groups. Significant comparisons are marked with a red star (* = p = value ≤ 0.05).

Figure 10

Comparison of the mean surface hardness values between the six study groups in each of the tested materials (HP, 3DP). A highly statistically significant difference is detected among the six groups of the two study materials, showing a noticeable superiority of the HP material over the 3DP material.

Figure 11

Multiple comparisons of mean surface hardness values among the six study groups using the HP material. Significant comparisons are marked with a red star (* = p = value ≤ 0.05).

Figure 12

Multiple comparisons of mean surface hardness values among the six study groups using the 3DP material. Significant comparisons are marked with a red star (* = p = value ≤ 0.05).

Figure 13

Comparison of mean surface hardness differences between the six study groups between the two tested materials. Significant comparisons are marked with a red star (* = p = value ≤ 0.05).