Background This study compared color parameters, hardness, surface roughness and topography, wettability, and water sorption (Wsp) of 3 denture base resins produced by 3-dimensional (3D) printing with digital light processing compared with a heat-polymerized polymethyl methacrylate (PMMA). Methods Disk-shaped specimens (14-mm diameter × 1.2-mm thickness) were fabricated from 4 denture base resins: 1 heat-polymerized PMMA (Vipi Wave; Vipi Dental Materials) and 3 3D-printed resins (Cosmos Denture Base [Yller Biomaterials], 3D PriZma Bio Denture [Makertech Labs], and Denture 3D+ [ND] [NextDent B.V.]). The 3D-printed specimens were produced using a digital light processing printer (90° building angle, 0.05-mm layer thickness) and postprocessed according to manufacturers’ instructions. PMMA specimens were prepared using the conventional compression molding technique and microwave polymerization. Evaluations included color parameters (International Commission on Illumination and color difference) (n = 9), Vickers hardness (n = 9), surface roughness (Ra) (n = 9), surface topography (n = 1), water contact angle (n = 6), and Wsp (n = 7). Data were tested for normality and analyzed using 1-way analysis of variance followed by Tukey post hoc test (α = 0.05). Results 3D-printed resins were not chromatically equivalent to heat-polymerized PMMA, although 3D PriZma Bio Denture showed statistically similar lightness values. The 3D-printed resins showed significantly higher Vickers hardness and lower surface roughness than PMMA. Among them, Cosmos Denture Base and ND had the lowest roughness; however, ND was also the most hydrophobic. All materials met the International Organization for Standardization 20795-1:2019 threshold of Wsp of 32 μg/mm3 or less. Conclusions 3D-printed denture base resins showed higher hardness and smoother surfaces than PMMA but lacked full color compatibility and varied across brands.
Background Accurate dental shade matching is essential for esthetic success. Digital shade matching devices have been introduced to improve objectivity, yet differences in measurement principles may influence performance. Methods This in vitro study evaluated the accuracy, repeatability, and value-based error of 4 digital devices: VITA Easyshade V (VITA Zahnfabrik), OptiShade (StyleItaliano), Cobra (Borea), and the TRIOS 5 (3Shape) intraoral scanner. All 19 tabs of the VITA Classical (VITA Zahnfabrik) shade guide, including bleached shades, were measured 3 times per device. Outcomes included correct shade and hue identification, repeatability, ordinal value errors, and color-difference–weighted metrics. Analyses were performed with all tabs and with bleached tabs excluded. Results Significant differences were observed among devices. OptiShade and Cobra showed higher accuracy and smaller perceptual deviations than TRIOS 5 and VITA Easyshade V across most analyses. Cobra was the only device to correctly identify bleached shades. Even when exact shade identification was not achieved, OptiShade and Cobra tended to select perceptually closer shades. VITA Easyshade V exhibited the highest repeatability despite lower accuracy, whereas TRIOS 5 showed lower repeatability. Excluding bleached tabs improved OptiShade performance but had minimal effect on Cobra’s performance. Conclusions Digital shade matching devices differ substantially in performance. Devices specifically designed for color measurement tended to indicate shades perceptually closer to the true tab than scanner-based or point-measurement systems.
Background Fiber post removal is an increasingly common endodontic procedure. This study evaluated root canal volumetric changes after fiber post removal using static navigation in endodontics, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and ultrasonic instrumentation techniques. Methods Forty-five extracted single-rooted human teeth with oval canals were treated in vitro. Fiber posts (1.2-mm diameter, 12-mm long, ≈ 5-mm apical) were cemented with composite resin. On the basis of cone-beam computed tomography–measured canal volume after post space preparation, specimens were randomly assigned to static navigation in endodontics, Er:YAG laser with noncoated bur, or ultrasonic instrumentation groups. Cone-beam computed tomographic scans evaluated canal volume changes after preparation and post removal as well as lateral perforations. Data were analyzed at a 5% significance level (α = 0.05). Normality was confirmed using the Kolmogorov-Smirnov test, followed by pair t test and 1-way analysis of variance for intragroup and intergroup comparisons, respectively. Results The ultrasonic instrumentation group showed no significant difference in dentin loss or residual material (P > .05). Canal volume decreased significantly in the static navigation in endodontics group, indicating residual material, and increased in the laser group, reflecting greater dentin removal (P < .05). No baseline differences were found (P > .05). Post removal volume was lowest in the static navigation in endodontics group. No perforations occurred in the static navigation in endodontics or laser groups, whereas the ultrasonic instrumentation group showed a 20% perforation rate. These perforations were recorded separately as procedural complications and were excluded from volumetric analysis. Conclusions The Er:YAG laser caused the greatest dentin loss but no perforations. Static navigation was safer than ultrasonic instrumentation techniques, whereas both static navigation in endodontics and ultrasonic instrumentation methods showed effective dentin preservation.
Background Substrate background effects on resin composite optical properties are poorly characterized, and interbrand variability challenges material interchangeability despite identical shade designation. This study characterized and compared the optical properties of dental composites available in different opacity levels and determined the effect of substrate on lightness and chromatic coordinates. Methods Nine brands of resin composites (shade A2) were evaluated: 6 systems with 3 opacity levels (Epic [Biodinâmica], Forma [Ultradent Products, Inc], Filtek Z350 XT [Solventum], Innova [Vigodent], Clearfil AP-X ES-2 [Kuraray Noritake Dental], Zirconfill [BM4]) and 3 with 2 levels (IPS Empress Direct [Ivoclar Vivadent], Vittra APS [FGM], Opallis [FGM]). Specimens were fabricated and stored dry for 24 hours. Color coordinates (lightness [L∗], red-green axis [a∗], yellow-blue axis [b∗]) were measured against white and black backgrounds. Translucency parameter (TP) was calculated. Data were analyzed using analysis of variance and Tukey test (α = 0.05). Results Significant differences in L∗, a∗, b∗, and TP were found among brands and opacity levels within each brand. Over a white background, dentin shades exhibited the highest L∗ values. Over black, all L∗ values decreased, with the smallest reduction observed in dentin shades. The a∗ and b∗ values significantly decreased over the black background. TP was highest for enamel shades and lowest for dentin shades. Conclusions The optical behavior of resin composites in shade A2 varies significantly by brand and opacity level. Dentin shades provide superior masking ability with minimal color shift over dark backgrounds, whereas enamel shades are highly translucent and substrate dependent.
