Search Results (27)

Objectives: To examine the effects of surface treatments on the color stability, surface roughness, surface gloss, and wettability of monolithic polychromatic material jetting (MJT) 3D-printed denture material. Material and Methods: Twenty-one color variants of the same denture material (TrueDent; Stratasys, Eden, MN, USA) underwent two surface treatments (polishing only or polishing and glazing), creating 42 study groups with a total of 420 samples (n = 10 per group). The samples were manufactured using a PolyJet 3D printer (J5 DentaJet; Stratasys, Eden, MN, USA), a type of MJT 3D printer. Color measurements were taken with a digital spectrophotometer before and after the surface treatments, and quantitative color differences (ΔE₀₀ and ΔC*) were calculated using the CIE2000 system. Comparisons of ΔE₀₀ were made against the 50%:50% acceptability threshold (AT) of 1.8 and the 50%:50% perceptibility threshold (PT) of 0.8 for tooth shade, as well as the 50%:50% PT of 1.72 and the 50%:50% AT of 4.08 for gingival (pink) shade. After surface treatment, the gloss was measured using a glossmeter, surface roughness was measured with optical profilometry, and wettability was measured by contact angle measurements using an optical tensiometer. The significance of surface treatment on color changes for each color variant was evaluated using one-sided, one-sample t-tests against the AT and PT. The effects of surface treatment on surface gloss, surface roughness, contact angle, and ΔC* were analyzed using t-tests for each color variant. Pairwise comparisons between groups were made using Fisher’s Protected Least Significant Differences (α = 0.05). Results: In most cases, glazing caused the color change (ΔE₀₀) to exceed the AT and PT, with a few exceptions. Most materials exhibited a more vibrant (more saturated) appearance and statistically higher chroma, with glazed surface treatments compared to polished ones, though there were some exceptions. For all materials, the glazed samples had significantly higher gloss units than the polished ones (p < 0.0001). Additionally, all materials showed significantly higher surface roughness in glazed samples compared to polished ones (p < 0.0001 for most). The polished samples had significantly higher contact angles (p < 0.0001 for most). Conclusions: Surface treatments significantly influenced the color, surface gloss, surface roughness, and wettability of MJT 3D-printed denture materials. Glazing led to increased chroma and gloss and produced more hydrophilic surfaces, although it also increased surface roughness. These results highlight the importance of surface treatment selection in optimizing the clinical performance of MJT-fabricated dentures. Full article

This scoping review aims to provide comprehensive evidence on methods used to assess the accuracy and acceptance of three-dimensional (3D)-printed removable partial dentures (RPDs). An electronic search of English language literature from January 2014 to 2024 was performed on five databases, PubMed, Scopus, Web of Science, EMBASE, and Google Scholar, using MesH terms. The parameter of interest was extracted and presented in tabular form. Of 1025 retrieved studies, 35 studies were included in the final analysis. Most studies were laboratory-based, and clinical trials were conducted between 2018 and 2022 without a control group. The studies included the use of the stone model or duplication model as a reference, as well as the direct 3D printing method and polished frame for detecting the accuracy of fit. The assessment method was divided into two categories: (1) qualitative (visual and tactile method) and (2) quantitative assessment, which includes optical and computerized methods for assessing the accuracy of fit. Dentist perception and patient-related outcomes were evaluated to measure the acceptance of 3D-printed RPDs. In conclusion, patients’ satisfaction and dentists’ acceptance of digitally printed RPDs were greater than those of conventional ones. The quantitative method (mainly computerized) provides a more accurate and precise assessment to evaluate the accuracy of fit. It allows clinicians to detect minute changes that cannot be inspected with visual and optical methods. Full article

This study aimed to investigate the release of metallic ions from cobalt–chromium (Co-Cr) alloys fabricated by additive manufacturing (AM) for comparison with dental casting. Co-Cr alloys were fabricated via AM using selective laser melting (SLM) and electron beam melting (EBM) in powder-bed fusion. Polished and mechanically ground specimens were prepared. Each specimen was analyzed using an electron probe microanalyzer (EPMA). Each specimen was immersed in an acidic saline solution for 7 days in accordance with ISO 10271: 2020. The EPMA indicated the segregation of some elements in the as-prepared SLM and EBM specimens, whereas the polished and ground specimens exhibited a homogenous elemental distribution. The total amount of ion release from the SLM and EBM specimens was confirmed to be less than 7 μg/cm², which was less than 42 μg/cm² for the cast specimen. The polished and ground specimens exhibited an even lower ion release than the as-prepared specimens. The amount of ions released from the Co-Cr alloy was less than the 200 μg/cm² requirement of ISO 22674: 2022. Co-Cr alloys fabricated by SLM and EBM could provide superior corrosion resistance to cast specimens. AM could be a valuable method for fabricating appliances and denture frameworks in dentistry. Full article

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. Full article

This in vitro study investigated how varying magnifications (5×, 10×, 20×, and 50×) using a confocal laser scanning microscope (CLSM) influence the measured surface roughness parameters, R_a/S_a and R_z/S_z, of various materials with two surface treatments. Cylindrical specimens (d ≈ 8 mm, h ≈ 3 mm, n = 10) from titanium, zirconia, glass-ceramic, denture base material, and composite underwent diamond treatment (80 μm; wet) and polishing (#4000; wet; Tegramin-25, Struers, G). The surface roughness parameters (R_a/S_a, R_z/S_z) were measured with a CLSM (VK-100, Keyence, J) at 5×, 10×, 20×, and 50× magnifications. Line roughness (R_a/R_z) was measured along a 1000 μm distance in three parallel lines, while area roughness (S_a/S_z) was evaluated over a 2500 μm × 1900 μm area. The statistical analysis included ANOVA, the Bonferroni post hoc test, and Pearson correlation (SPSS 29, IBM, USA; α = 0.05). R_a/S_a and R_z/S_z showed significant differences (p ≤ 0.001, ANOVA) across magnifications, with values decreasing as magnification increased, highest at 5× and lowest at 50×. Titanium, zirconia, and glass-ceramic showed significant measured roughness values from 5× to 50×. Denture base material and composite had lower measured roughness values, especially after polishing. Line and area roughness varied significantly, indicating that magnification affects measured values. Standardizing magnifications is essential to ensure comparability between studies. A 50× magnification captures more detailed profile information while masking larger defects. Full article

In this study, we aimed to investigate the differences in tissue surface adaptation and the variations in distances between reference points on the polished surfaces of 3D-printed denture bases produced at different build angles. The build angles were 0°, 30°, 60°, and 90°, with 15 denture bases printed for each angle. Using the Geomagic Control^® software, a 3D best-fit alignment was conducted between the denture base tissue surface and the reference shape of the edentulous maxilla model to calculate the root mean square error. The distances between reference points on the polished surface were measured using digital calipers. A one-way analysis of variance was conducted for statistical analysis. The adaptation, as measured by the root mean square error, varied significantly among denture bases with different build angles. The distances between the anterior and posterior reference points of the polished surface were also significantly different. However, within the limitations of this study, the variations in adaptations and dimensional accuracy across different build angles were within clinically acceptable ranges. In clinical practice, the print angle can be adjusted based on factors such as printing time, resin consumption, and the number of denture bases being printed simultaneously. Full article

Additive manufacturing resins used in dental prosthetics may retain uncured monomers post-polymerization, posing potential long-term patient exposure risks. Understanding the biological safety of these materials is crucial, particularly for 3D-printed acrylic-based prosthodontic devices such as occlusal nightguards, complete and partial dentures, and temporary fixed prostheses. This paper reviews the literature evaluating the cytotoxicity of such materials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a scoping review using the MESH keywords related to population (P), intervention (I), comparison (C), and outcome (O) across databases, including OVID Medline, EMBASE, and SCOPUS. Our search, limited to peer-reviewed English language articles from 2015 to 2023, resulted in 22 papers. These studies, utilizing digital light processing (DLP) or stereolithography (SLA) printing methods, varied in examining different 3D-printed materials, as well as washing and post-curing protocols. The primary experimental cells used were human gingival fibroblasts (HGF) and mouse fibroblasts (L929). There are no statistical differences in biocompatibility regarding different commercially available resins, washing solutions, or methods. Improvements in cell viability were related to an increase in washing time, as well as post-curing time. After the polishing procedure, 3D resin-based printed occlusal devices perform similarly to milled and conventionally processed ones. Our findings underline the importance of appropriate washing and post-curing protocols in minimizing the cytotoxic risks associated with these 3D-printed resin-based devices. Full article

The aim of the current study was to present the clinical and radiological outcomes of monolithic zirconia superstructures compared to the metal–ceramic ones in the All-on-4 concept for the prosthetic rehabilitation of the maxillae. A total of 30 patients were subdivided into groups according to their superstructure type (metal–ceramic (n = 15) or monolithic zirconia (n = 15)). All implants were functionally loaded within 24 h after insertion with provisional acrylic superstructures. Prosthetic complications, marginal bone loss, plaque accumulation, probing pocket depth, bleeding on probing, and bite force were documented over a period of 5 years. Marginal bone loss around the implants of the ceramic group remained well over the five years (1.21 ± 0.23 mm). However, marginal bone loss was significantly lower around the implants in the monolithic zirconia group (0.22 ± 0.14 mm) (p < 0.001). Bleeding on probing, plaque accumulation, and probing pocket depth values were correlated with marginal bone loss. Among all evaluated parameters, no differences could be detected in terms of the angulation of the implants. Detachment or chipping was observed in seven cases in the metal–ceramic superstructure group. In all cases, dentures were removed and repaired in the laboratory. In the monolithic zirconia group, chipping was detected after one year in two cases, after two years in four cases, and after five years in one case and could be managed by polishing in situ. Monolithic zirconia superstructures presented superior results regarding the parameters evaluated. Full article

(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. Full article

This review focuses on the current disparities and gaps in research on the characteristics of the oral ecosystem of denture wearers, making a unique contribution to the literature on this topic. We aimed to synthesize the literature on the state of current knowledge concerning the biological behavior of the different polymers used in prosthetics. Whichever polymer is used in the composition of the prosthetic base (poly methyl methacrylate acrylic (PMMA), polyamide (PA), or polyether ether ketone (PEEK)), the simple presence of a removable prosthesis in the oral cavity can disturb the balance of the oral microbiota. This phenomenon is aggravated by poor oral hygiene, resulting in an increased microbial load coupled with the reduced salivation that is associated with older patients. In 15–70% of patients, this imbalance leads to the appearance of inflammation under the prosthesis (denture stomatitis, DS). DS is dependent on the equilibrium—as well as on the reciprocal, fragile, and constantly dynamic conditions—between the host and the microbiome in the oral cavity. Several local and general parameters contribute to this balance. Locally, the formation of microbial plaque on dentures (DMP) depends on the phenomena of adhesion, aggregation, and accumulation of microorganisms. To limit DMP, apart from oral and lifestyle hygiene, the prosthesis must be polished and regularly immersed in a disinfectant bath. It can also be covered with an insulating coating. In the long term, relining and maintenance of the prosthesis must also be established to control microbial proliferation. On the other hand, several general conditions specific to the host (aging; heredity; allergies; diseases such as diabetes mellitus or cardiovascular, respiratory, or digestive diseases; and immunodeficiencies) can make the management of DS difficult. Thus, the second part of this review addresses the complexity of the management of DMP depending on the polymer used. The methodology followed in this review comprised the formulation of a search strategy, definition of the inclusion and exclusion criteria, and selection of studies for analysis. The PubMed database was searched independently for pertinent studies. A total of 213 titles were retrieved from the electronic databases, and after applying the exclusion criteria, we selected 84 articles on the possible microbial interactions between the prosthesis and the oral environment, with a particular emphasis on Candida albicans. Full article

Partial or complete dentures are constructed from thermoplastic resins that are thermally processed and molded. This review examines the presently available evidence for the cytotoxicity of thermoplasticized denture base resins on human gingival epithelial cells, adipose cells, and fibroblasts; human amnion fibroblasts; and mouse fibroblasts. Electronic searches were performed on PubMed, Scopus, Web of Science, and Google Scholar databases to identify relevant articles to be included in the review until September 2022. Clinical, in vivo, and in vitro studies in English language were searched for. The quality of the studies was assessed using the Toxicological data Reliability Assessment tool (ToxRTool) developed by the European Commission’s Joint Research Centre. GRADE assessment was used to evaluate the certainty of evidence. Seven in vitro studies were included in the review. The overall risk of bias was determined to be high, with the majority of studies assessed found to be reliable with restrictions or not reliable. Only two studies were considered reliable without restrictions based on ToxRTool assessment. The effect of thermoplastic denture base resins on viability and cell adherence of human gingival or amnion fibroblasts and mouse fibroblasts (L929s) is not significant. Conditioned media from unpolished specimens of resins were significantly more toxic to cultured cells than those from polished specimens. This may be of concern in cases of poor post-processing of dentures. Based on the limited evidence available, there is low-certainty evidence that thermoplastic denture base resins appear to be biocompatible and show insignificant cytotoxicity. Further well-designed trials adhering to standard reporting guidelines and using objective measures are necessary before outlining universal guidelines for best practice. Long-term in vivo and clinical assessment is necessary to corroborate laboratory findings with clinical outcomes. Denture base resins are in constant contact with oral tissues, and cytotoxic components released by the resins may irritate or inflame the tissues or provoke an allergic response. Full article

Chairside polishing kits are an alternative to laboratory polishing techniques. The effects of using a chairside polishing kit on a three-dimensional (3D)-printed acrylic denture base (ADB) have not been reported previously. Thus, this study aimed to evaluate the effects of different chairside polishing techniques on the surface characterizations of ABD, including surface roughness average (Ra), average maximum profile height (Rz), and scanning electron microscopy (SEM) representations. One hundred and twenty disc-shaped specimens were fabricated from one conventional heat-polymerized (HP) ADB resin and two 3D-printed (Asiga (AS) and NextDent (ND)) ADB resins (n = 40 per material). Each group was further divided based on the polishing protocol (n = 10) as follows: conventional polishing protocol (C), microdont chairside polishing kit (M), shofu chairside polishing kit (S), and an unpolished group (U). The Ra and Rz values were measured using an optical profilometer. Two-way ANOVA and post hoc tests were used for data analysis (α = 0.05) at significant levels. In unpolished groups, there was a statistically significant difference between HP-U vs. AS-U and ND-U groups (p < 0.0001). For Ra, the lowest values were observed in HP-C, AS-S, and ND-C. While the highest values were shown in all unpolished groups. Within the material, there were statistically significant differences between the three polishing protocols (C, M, and S) vs. unpolished (p < 0.0001), while there was no significant between C, M, and S groups (p = 0.05). The Rz values had the same pattern as the Ra values. The two chairside polishing kits were comparable to conventional polishing techniques, and they can be recommended for clinical application. Full article

Background: Color stability is a crucial performance parameter for dental restorations, and limited research exists on how surface preparation methods affect it. The purpose of this study was to test the color stability of three resins intended for 3D printing, which can be used to make dentures or crowns in A2 and A3 colors. Materials and Methods: Samples were prepared in the form of incisors; the first group was not subjected to any treatment after curing and washing with alcohol, the second was covered with light-curing varnish, and the third was polished in a standard way. Then, the samples were placed in solutions of coffee, red wine, and distilled water and stored in the laboratory. After 14, 30, and 60 days, color changes were measured (presented as Delta E) compared to material stored in the dark. Results: The greatest changes were observed for samples that were not polished, then were placed in red wine dilutions (ΔE = 18.19 ± 0.16). Regarding the samples covered with varnish, during storage, some parts detached, and the dyes penetrated inside. Conclusions: 3D-printed material should be polished as thoroughly as possible to limit the adhesion of dyes from food to their surface. Applying varnish may be a temporary solution. Full article

Poly(methyl methacrylate) (PMMA) is a commonly used material, as it is biocompatible and relatively cheap. However, its mechanical properties and weak antibiofilm activity are major concerns. With the development of new technology, 3D-printed resins are emerging as replacements for PMMA. Few studies have investigated the antibiofilm activity of 3D-printed resins. Therefore, this study aimed to investigate the antibiofilm activity and surface roughness of a 3D-printed denture base resin modified with different concentrations of zirconium dioxide nanoparticles (ZrO₂ NPs). A total of 60 resin disc specimens (15 × 2 mm) were fabricated and divided into six groups (n = 10). The groups comprised a heat-polymerized resin (PMMA) group, an unmodified 3D-printed resin (NextDent) group, and four 3D-printed resin groups that were modified with ZrO₂ NPs at various concentrations (0.5 wt%, 1 wt%, 3 wt%, and 5 wt%). All specimens were polished using a conventional method and then placed in a thermocycler machine for 5000 cycles. Surface roughness (Ra, µm) was measured using a non-contact profilometer. The adhesion of Candida albicans (C. albicans) was measured using a fungal adhesion assay that consisted of a colony forming unit assay and a cell proliferation assay. The data were analyzed using Shapiro–Wilk and Kruskal–Wallis tests. A Mann–Whitney U test was used for pairwise comparison, and p-values of less than 0.05 were considered statistically significant. The lowest Ra value (0.88 ± 0.087 µm) was recorded for the PMMA group. In comparison to the PMMA group, the 3% ZrO₂ NPs 3D-printed group showed a significant increase in Ra (p < 0.025). For the 3D-printed resins, significant differences were found between the groups with 0% vs. 3% ZrO₂ NPs and 3% vs. 5% ZrO₂ NPs (p < 0.025). The highest Ra value (0.96 ± 0.06 µm) was recorded for the 3% ZrO₂ NPs group, and the lowest Ra values (0.91 ± 0.03 µm) were recorded for the 0.5% and 5% ZrO₂ NPs groups. In terms of antifungal activity, the cell proliferation assay showed a significant decrease in the C. albicans count for the 0.5% ZrO₂ NPs group when compared with PMMA and all other groups of 3D-printed resins. The group with the lowest concentration of ZrO₂ NPs (0.5%) showed the lowest level of C. albicans adhesion of all the tested groups and showed the lowest Candida count (0.29 ± 0.03). The addition of ZrO₂ NPs in low concentrations did not affect the surface roughness of the 3D-printed resins. These 3D-printed resins with low concentrations of nanocomposites could be used as possible materials for the prevention and treatment of denture stomatitis, due to their antibiofilm activities. Full article

Digital technology facilitates the manufacturing of complete dentures; however, clinical and patient-reported outcomes are underreported. This prospective, randomized, single-blind cross-over study reports the clinical and patient-related outcomes of 10 edentulous patients receiving digital dentures prepared with the Vita Vionic System and conventional dentures produced from heat-polymerized polymethylmethacrylate resin. Clinical efficiency was stated based on the Sato score for quantitative assessment of complete denture quality. Patient satisfaction was evaluated with the oral health-related quality of life questionnaire (OHIP-20). We report here that the Sato score was slightly higher in patients receiving digital versus conventional dentures with a mean of 73.2 ± 12.3 and 67.4 ± 11.8, respectively (p = 0.16). Moreover, upper and lower stability was superior in digital dentures (p = 0.03 and p = 0.10, respectively), while denture polish was better in conventional dentures (p = 0.03). Quality of life was slightly higher in patients receiving conventional compared to digital dentures with an OHIP-20 of 101.7 ± 12.0 and 95.6 ± 24.2, respectively (p = 0.33). Taken together and when considering the low power of the study, our findings suggest a trend towards better clinical efficiency of digital compared to conventional dentures, while patient satisfaction remained unaffected by the type of manufacturing. Full article