This study aimed to evaluate the water sorption, solubility, and translucency of 3D-printed denture base resins (NextDent, FormLabs, and Asiga), compare them to heat-polymerized acrylic denture base resins, and assess their performance under the effects of thermal cycling. A total of 80 acrylic disc specimens were used in the current study, categorized into four groups (n = 10); in one group, the samples were fabricated conventionally with a heat-polymerizing process (control), while the other three groups were fabricated digitally from different 3D-printed reins (NextDent, FormLabs, and Asiga). Specimens were fabricated according to the manufacturers’ recommendations and immersed in distilled water for 48 h at 37 °C. Data on water sorption, solubility, and translucency measurements (T1) were obtained. All the specimens were subjected to 5000 thermal cycles, and then the measures were repeated using the same method (T2). Data analysis was attained via ANOVA and the post hoc Tukey test (α = 0.05). The type of resin significantly affected the values of water sorption, solubility, and translucency (p < 0.001). The water sorption of 3D-printed resins was increased significantly in comparison to control with or without a thermal cycling effect. In terms of solubility, a significant increase in 3D-printed resins before thermocycling was observed; however, after thermocycling, Asiga had a significantly low value compared to the other groups (p < 0.001). Thermal cycling increased the water sorption and solubility of all tested materials. In comparison to control, the translucency of the 3D-printed resins was significantly decreased (p < 0.001). The translucency was significantly decreased per material in terms of the thermal cycling effect (before and after). NextDent showed significantly low translucency values (p < 0.001) compared to the other groups. All 3D-printed resin groups had higher water sorption and solubility and lower translucency values in comparison to the heat-polymerized resin group. Regardless of resin types, thermal cycling adversely affected all tested properties.

The effect of printing parameters on the surface characteristics of three-dimensional (3D)-printed denture base resins (DBRs) is neglected. Therefore, this study investigated the effect of printing orientation and post-curing time on the surface roughness and hardness. One conventional heat-polymerized (HP) resin and two 3D-printing resins (NextDent (ND) and ASIGA (AS)) were used to fabricate a total of 250-disc (10 × 2.5 mm) specimens. ND and AS specimens were printed with different orientations (0-, 45-, and 90-degree) and each orientation group was subjected to four post-curing times (30, 60, 90, 120 min). Printed specimens were thermo-cycled (10,000 cycles) followed by the measuring of surface roughness (Profilometer (Ra)) and hardness (a Vickers hardness (VH)). ANOVA and post hoc tests were used for data analysis (α = 0.05) at significant levels. AS and ND showed no significant changes in Ra when compared with HP (p ˃ 0.05), except the 45-degree orientation (AS/90 min and AS/120 min) significantly increased surface roughness (p ˂ 0.001). There was no significant difference in Ra with different orientations and post-curing time for both materials AS and ND (p ˃ 0.05). Compared with HP, 3D-printed DBRs showed low VH values (p ˂ 0.001). For AS, 90-degree orientation showed a significant decrease in VH at 60, 90, and 120 min when compared with 0- and 45-degree orientation (p ˂ 0.001), while ND showed no significant difference in VH with different printing orientations (p ˃ 0.05). The VH of AS and ND improved when increasing post-curing time to 120 min (p ˂ 0.001), and the printing orientations and post-curing time did not affect the Ra of 3D-printed DBRs.

Due to the low mechanical performances of 3D-printed denture base resins, ZrO₂ nanoparticles (ZrO₂NPs) were incorporated into different 3D-printed resins and their effects on the flexure strength, elastic modulus, impact strength, hardness, and surface roughness were evaluated. A total of 286 specimens were fabricated in dimensions per respective test and divided according to materials into three groups: heat-polymerized as a control group and two 3D-printed resins (NextDent and ASIGA) which were modified with 0.5 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% ZrO₂NPs. The flexure strength and elastic modulus, impact strength, hardness, and surface roughness (µm) were measured using the three-point bending test, Charpy’s impact test, Vickers hardness test, and a profilometer, respectively. The data were analyzed by ANOVA and Tukey’s post hoc test (α = 0.05). The results showed that, in comparison to heat-polymerized resin, the unmodified 3D-printed resins showed a significant decrease in all tested properties (p < 0.001) except surface roughness (p = 0.11). In between 3D-printed resins, the addition of ZrO₂NPs to 3D-printed resins showed a significant increase in flexure strength, impact strength, and hardness (p < 0.05) while showing no significant differences in surface roughness and elastic modulus (p > 0.05). Our study demonstrated that the unmodified 3D-printed resins showed inferior mechanical behavior when compared with heat-polymerized acrylic resin while the addition of ZrO₂NPs improved the properties of 3D-printed resins. Therefore, the introduced 3D-printable nanocomposite denture-base resins are suitable for clinical use.

OBJECTIVE: To determine the prevalence of caries in the primary and permanent teeth in a Saudi population. METHODS: This study was conducted at the College of Dentistry, University of Dammam, Dammam, Kingdom of Saudi Arabia. In June 2010, a literature search was started and found all studies conducted in Saudi Arabia on dental caries from 1999 to 2008. Sixty articles were found on PubMed, which had been published during the considered time period. Sixteen studies were passed through inclusion criteria and included in analysis. A 2 to 12-year-old Saudi population was included to determine the prevalence of caries in primary teeth, and for permanent teeth, the age range was 6-18 years. RESULTS: The prevalence of caries in primary and permanent teeth were analyzed separately. Forest plot and Chi-square test revealed considerable heterogeneity. A random effect model was used to find caries prevalence in primary and permanent teeth. The mean decayed, missing, and filled teeth (dmft) was 5.38 (95% CI: 4.314 - 6.436), and in the permanent teeth the DMFT was 3.34 (95% CI: 1.97 - 4.75). Publication bias diagnostics suggested possible overestimation of caries prevalence in permanent teeth but not in primary teeth. CONCLUSION: The results in this study present a high decayed, missing, and filled teeth score in the adult and young population of Saudi Arabia, however, more published data is required as the results obtained from this meta analysis may not give a true picture, and reality may be worse.