This investigation aims to determine the effect of the same polishing protocol on the surface roughness (Ra) of different resins obtained by different processing techniques. Acrylic resins obtained by CAD/CAM technology overcame the disadvantages identified in conventional materials. A total of thirty samples (six of each resin): self-cured, heat-polymerized, injection molded, CAD/CAM 3D-printed and CAD/CAM milled were prepared. JOTA^® Kit 1877 DENTUR POLISH was used to polish the samples by two techniques: manual and mechanized, with a prototype for guided polishing exclusively developed for this investigation. The Ra was measured by a profilometer. The values were analyzed using ANOVA, Games–Howell post-hoc test and One-sample t-test, with p < 0.05. Manual polishing produces lower values of Ra compared to mechanized polishing, except for injected molded resins (p = 0.713). Manual polishing reveals significant differences between the resin pairs milling/3D-printing (p = 0.012) and thermopolymerizable/milling (p = 0.024). In the mechanized technique only, significant differences regarding the R_a values were found between the self-cured/3D-printed (p = 0.004) and self-cured/thermopolymerizable pair resins (p = 0.004). Differences in surface roughness values can be attributed to the inherent characteristics of the resin and the respective processing techniques.

(1) Introduction: Apart from the polishing method, conventional or mechanized, the arithmetic mean roughness (Ra) is the most common metric to evaluate the surface roughness of denture base acrylic resins. An overview of the constraints related to this roughness parameter is highlighted in this study. This research introduces new parameters for accessing a functional analysis of surface roughness. (2) Materials and Methods: Five samples of CAD/CAM 3D-printed acrylic resins were prepared. Two polishing techniques, manual and mechanical, were applied. Surface roughness parameters were extracted from a profilometer reading: arithmetic mean height (Ra and Pa), skewness (Rsk and Psk), and kurtosis (Rku and Pku). (3) Results: Significant differences (p < 0.001) were found in the Ra distribution among the study samples, in contrast with the lack of significance in Pa values. Surface roughness parameters revealed an increased coefficient of variance (CV) value due to mechanized polishing across the specimens analyzed. Skewness and kurtosis indicate a more pronounced distribution with the manual polishing technique. (4) Conclusion: This preliminary study exhibits the influence of different polishing protocols on surface roughness parameters. The primary profile, skewness, and kurtosis should be assessed for the surface characterization of acrylic resins.

Background: Different processing techniques are employed to obtain poly (methyl methacrylate) (PMMA) with consistent surface quality in terms of topography and tribological function. The purpose of this research is to evaluate its influence on the surface height distribution. Methods: In this research, samples of conventional and CAD/CAM acrylic resins were prepared. The following surface roughness parameters were extracted from the profilometric readings: arithmetic mean roughness (Pa), skewness (Psk) and kurtosis (Pku). Profilometric profiles were additionally obtained. Results: The average roughness (Pa) with the conventional technique was significantly higher compared to CAD/CAM (t = 4.595; P < 0.001). Heat-cured resins presented the highest mean Pa (F = 6.975; P = 0.06). Heat-cured and milled resins show lower coefficient variation (CV) values, indicating more consistent surface finishing. The surface profiles revealed distinct characteristics in terms of skewness and kurtosis. Conclusions: The surface processing method, chemical composition and resin type significantly influence the surface finishing of the resin. The CAD/CAM resins exhibited superior results in terms of surface arithmetic mean roughness (Pa). However, heat-cured resin revealed to present the better surface consistency.

Surface roughness is primarily determined by the inherent characteristics of a material, the specific polishing protocol and the manual operator’s dexterity. This research intends to conduct a comparative analysis between a conventional and mechanized polishing protocol concerning surface roughness and its impact on surface topography. Thirty samples were included in this in vitro study: six samples for each type of acrylic resin. All specimens underwent a polishing protocol by a conventional method and a mechanized approach with a controlled polishing tool (CPT). Profilometric measures were extracted: arithmetic mean height (Pa), skewness (Psk) and kurtosis (Pku). The Pa values acquired through both the mechanized and conventional polishing techniques are significantly lower compared to the control group. The mechanized polishing notably yielded higher roughness compared to the control group. Relatively consistent skewness and lower-to-moderate values of kurtosis were found across resin types. Differences in the dispersion and pattern for Pa were not detected between the polishing protocols. The CPT protocol reliably maintains consistent skewness and kurtosis values. The conventional protocol remains significant due to the variations observed in the Pa values obtained.

Background: Surface roughness and microbial adhesion are key determinants of the biological performance of prosthetic base resins. This study evaluated Candida albicans (ATCC 11225) and Streptococcus mutans (DSM 20523) adhesion to a conventional heat-polymerized acrylic resin (Probase Hot) and a 3D-printed resin (V-Print dentbase) fabricated at 0° and 90° build orientations. Methods: Fifteen disc-shaped specimens (10 mm × 2 mm) were polished using a standardized protocol and surface roughness was characterized by contact profilometry (Ra). After UV sterilization, specimens were incubated for 24 h with standardized suspensions of C. albicans or S. mutans. Microbial adhesion was assessed qualitatively by scanning electron microscopy (SEM). Statistical analysis was performed using one-way ANOVA with Tukey’s post hoc test after confirmation of normality (Shapiro–Wilk) and homogeneity of variances (Levene). Statistical significance was set at p < 0.05, and Cohen’s d was calculated to estimate effect size. Results: Surface roughness differed significantly among fabrication conditions (p = 0.017), with the conventional heat-polymerized resin showing the highest Ra values and the 3D-printed resin fabricated at 90° presenting the lowest roughness. SEM observations suggested a similar adhesion pattern for both C. albicans and S. mutans, with greater apparent microbial presence on 90°-printed specimens, followed by the conventional heat-polymerized resin, whereas 0°-printed specimens showed lower apparent adhesion in the analyzed fields. Conclusions: These findings suggest that printing orientation may influence surface-associated microbial adhesion patterns in 3D-printed prosthetic resins; however, further studies with larger sample sizes, orientation-specific surface characterization, and mono- and multispecies biofilm models are warranted to confirm these preliminary findings.