Ariel J Raigrodski’s research while affiliated with University of Washington and other places

Purpose: To measure the influence of best-fit (BF) algorithms (entire dataset, 3 or 6 points landmark-based, or section-based BF) on virtual casts and their alignment discrepancies. Material and methods: A mandibular typodont was obtained and digitized by using an industrial scanner (GOM Atos Q 3D 12M). A control mesh was acquired. The typodont was digitized by using an intraoral scanner (TRIOS 4). Based on the alignment procedures, four groups were created: BF of the entire dataset (BF group), landmark-based BF using 3 reference points (LBF-3 group), or 6 reference points (LBF-6 group), and section-based BF (SBF group). The root mean square (RMS) error was calculated. One-way ANOVA and post-hoc pairwise multi-comparison Tukey were used to analyze the data (α = .05). Results: Significant RMS error mean value differences were found across the groups (P<.001). Tukey test revealed significant RMS error mean value differences between the BF and LBF-3 groups (P = .022), BF and LBF-6 groups (P<.001), LB-3 and LB-6 groups (P<.001), LBF-3 and SBF groups (P<.001), and LBF-6 and SBF groups (P<.001). The LBF-6 group had the lowest trueness, while SBF and BF groups obtained the highest trueness values. Furthermore, significant SD differences were revealed across the groups tested (P<.001). Tukey test revealed significant SD differences between the BF and LBF-6 groups (P<.001), LBF-3 and LB-6 groups (P<.001), LBF-3 and SBF groups (P = .004), and LBF-6 and SBF groups (P<.001). The BF and SBF groups showed equal and highest precision, while the LBF-6 group had the lowest precision. Conclusions: The best-fit algorithms tested influenced the virtual casts' alignment discrepancy. Entire dataset or section-based best-fit algorithms obtained the highest virtual casts' alignment trueness and precision compared with the landmark-based method.

Purpose: To assess the implant-abutment discrepancy of complete-arch frameworks manufactured using milling and additive electron beam melting (EBM) technologies, before and after acrylic resin veneering application. Materials and methods: A definitive implant cast with six implant replicas was digitized using a laboratory scanner. A software program was used to design an implant-supported framework which was manufactured using milling (M group) and EBM (EBM group) technologies (n = 10). In the M group, titanium milled specimens were fabricated. In the EBM group, titanium EBM specimens were obtained. A coordinate measurement machine (CMM) was used to assess the implant-abutment discrepancy at x-, y-, and z-axed between the specimens and the implant-abutment replicas of the definitive cast. The implant replicas positioned on the lateral incisor positions were not able to be assessed. The 3D gap discrepancy was calculated: 3 D = x 2 + y 2 + z 2 $3D\ = \sqrt {{x^2} + {y^2} + {z^2}}$ . Acrylic resin veneering procedures were finished and the same CMM measurements were completed. Three-way analysis of variance (ANOVA) test was used to analyze the data (α = 0.05). Results: The manufacturing method (df = 1, F = 7.00, p = 0.009) and implant position (df = 3, F = 129.82, p < 0.001) were significant predictors of the x-axis discrepancy. The veneering procedures (df = 1, F = 21.55, p < 0.001) and implant position (df = 3, F = 95.42, p < 0.001) were significant predictors of the y-axis discrepancy. The manufacturing method (df = 1, F = 11.79, p = 0.001) was a significant predictor of the z-axis discrepancy. Lastly, the manufacturing method (df = 1, F = 5.11, p = 0.026), implant position (df = 3, F = 11.36, p < 0.001), and veneering procedures (df = 1, F = 41.56, p < 0.001) were significant predictors of the 3D gap discrepancy in which the manufacturing method explains the 2.37% of variation in the 3D gap discrepancy, the implant position explains the 15.82% of variation in the 3D gap discrepancy, and veneering procedures explain the 19.29% of variation in the 3D gap discrepancy results. Conclusions: The manufacturing methods, veneering procedures, and implant position influenced the linear implant-abutment discrepancy. The milled technique tested obtained lower linear implant-abutment discrepancy compared with the EBM method evaluated. The acrylic resin veneering procedures increased the implant-abutment discrepancy.

Statement of problem Lithography-based additively manufactured (AM) zirconia has been used to fabricate dental implants and custom barriers for guided bone regeneration procedures. However, studies on the effect of AM zirconia on the biological properties of human osteoblasts are lacking. Purpose The purpose of this in vitro study was to compare the effect of milled and lithography-based AM zirconia on the biological properties of normal human osteoblasts (NHOsts), as well as to compare the chemical composition between the milled and lithography-based AM 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) zirconia. Material and methods Three mol percentage yttria-stabilized tetragonal zirconia polycrystal disks (Ø6×2-mm) were fabricated using subtractive milling (Priti multidisc ZrO2 monochrome) (M group) and lithography-based additive manufacturing methods (LithaCon 3Y 210) (AM group) (n=10). NHOsts were exposed to different material extracts (1:1, 1:2, and 1:4) and cytotoxicity, cell migration, cell morphology, and cell attachment biological tests were completed. Additionally, for morphological and chemical analysis, a scanning electronic microscopy with energy-dispersive X-ray analysis (SEM/EDX) evaluation was completed. Data were analyzed by using 1-way ANOVA and the Dunnett test (α=.05). Results Substantial cell attachment and spreading were observed in both material surfaces. The presence of zirconium was evident in both groups, although the percentage of zirconium in the AM group (64.7%) was slightly higher than in the M group (52.6%). When NHOsts were cultured in the presence of the different material eluates, the M and AM groups exhibited similar NHOst viability and migration rates when compared with untreated cells; no significant differences were found (P>.05). Conclusions The lithography-based AM zirconia tested showed adequate cytocompatibility without differences when compared with the milled zirconia (M group) specimens. Slight chemical element composition differences were found between milled and lithography-based AM zirconia.

Purpose. To evaluate the chemical composition, flexural strength, and Weibull characteristics of milled and lithography-based additively manufactured (AM) zirconia. Materials and Methods. A virtual design of a bar (25x4x2 mm) was completed using a software program. The standard tessellation language file was used to manufacture all the specimens: 3Y-TZP zirconia (Priti multidisc ZrO2 monochrome) milled (M group) and 3Y-TZP zirconia (LithaCon 3Y 210) lithography-based AM (CeraFab System S65 Medical) (AM group) bar specimens (n=20). The chemical composition of the specimens was determined by using energy dispersive X-ray (EDAX) elemental analysis in a scanning electron microscope. Flexural strength was measured in all specimens using 3-point bend test according to ISO/CD 6872.2 with a universal testing machine (Instron Model 8501). Two-parameter Weibull distribution values were calculated. The Shapiro-Wilk test revealed that the data were normally distributed (P<.05). Flexural strength values were analyzed using independent Student t-test (α=.05). Results. There were no major chemical composition differences observed between M and AM groups. The AM specimens (1518.9 ±253.9 MPa) exhibited a significantly higher flexural strength mean value compared to the milled (980.5 ±130.3 MPa) specimens (DF=13, T-value=-5.97, P<.001). The Weibull distribution presented the highest shape for AM specimens (11.49) compared to those of milled specimens (6.95). Conclusions. There was no significant difference in the chemical composition of milled and AM zirconia material tested. AM zirconia tested exhibited significantly higher flexural strength compared with the milled zirconia evaluated.

Statement of problem Vat-polymerized casts can be designed with different bases, but the influence of the base design on the accuracy of the casts remains unclear. Purpose The purpose of the present in vitro study was to evaluate the influence of various base designs (solid, honeycombed, and hollow) with 2 different wall thicknesses (1 mm and 2 mm) on the accuracy of vat-polymerized diagnostic casts. Material and methods A virtual maxillary cast was obtained and used to create 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were further divided into 2 subgroups based on the wall thickness of the cast designed: 1 mm (HC-1 and H-1) and 2 mm (HC-2 and H-2) (N=50, n=10). All the specimens were manufactured with a vat-polymerized printer (Nexdent 5100) and a resin material (Nexdent Model Ortho). The linear and 3D discrepancies between the virtual cast and each specimen were measured with a coordinate measuring machine. Trueness was defined as the mean of the average absolute dimensional discrepancy between the virtual cast and the AM specimens and precision as the standard deviation of the dimensional discrepancies between the virtual cast and the AM specimens. The Kolmogorov-Smirnov and Shapiro-Wilk tests revealed that the data were not normally distributed. The data were analyzed with Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05). Results The trueness ranged from 63.73 μm to 77.17 μm, and the precision ranged from 44.00 μm to 54.24 μm. The Kruskal-Wallis test revealed significant differences on the x- (P<.001), y- (P=.006), and z-axes (P<.001) and on the 3D discrepancy (P<.001). On the x-axis, the Mann-Whitney test revealed significant differences between the S and H-1 groups (P<.001), S and H-2 groups (P<.001), HC-1 and H-1 groups (P<.001), HC-1 and H-2 groups (P<.001), HC-2 and H-1 groups (P<.001), and HC-2 and H-2 groups (P<.001); on the y-axis, between the S and H-1 groups (P<.001), HC-1 and H-1 groups (P=.001), HC-1 and H-2 groups (P=.02), HC-2 and H-1 groups (P<.001), HC-2 and H-2 groups (P=.003); and on the z-axis, between the S and H-1 groups (P=.003). For the 3D discrepancy analysis, significant differences were found between the S and H-1 groups (P<.001), S and H-2 groups (P=.004), HC-1 and H-1 groups (P=.04), and HC-2 and H-1 groups (P=.002). Conclusions The base designs tested influenced the manufacturing accuracy of the diagnostic casts fabricated with a vat-polymerization printer, with the solid and honeycombed bases providing the greatest accuracy. However, all the specimens were clinically acceptable.

Interim veneers present an esthetic and functional challenge for restorative dentists. Moreover, inadequate fit or trauma to the soft tissue during their fabrication or subsequently may affect soft-tissue health and stability and lead to bleeding that will compromise the adhesive cementation of the definitive ceramic veneers. This article describes a technique for the atraumatic fabrication of interim veneers with a custom, rigid, clear matrix designed for multipurpose use during the patient’s restorative care. Based on a diagnostic waxing, the clear matrix is made and first used for the fabrication of the trial restorations and as a tooth-preparation guide. Subsequently, it is used for the atraumatic fabrication of interim veneers with a photopolymerizing direct restorative material.

Statement of problem Dental implants undergo various surface treatments. Studies that have characterized their surface and subsurface by using the same methods are scarce. Purpose The purpose of this study is to physically characterize the surface and subsurface of implant systems made of commercially pure (cp) titanium (Ti) grade (gr) 4 and Ti alloy gr 23 and to evaluate whether airborne-particle abrasion and acid etching is an appropriate surface treatment for Ti alloy gr 23. Material and methods Implant groups (n=3) were as follows: TG4AO, cp Ti gr 4, treated with anodic oxidation (3.5×8 mm) (NobelReplace Conical; Nobel Biocare); TG23AE, Ti gr 23 (TiAlV ELI) airborne-particle abraded-and-etched (3.9×8 mm) (V3; MIS); and TG4AE, cp Ti gr 4, airborne-particle abraded and etched (3.3×8 mm) (BL; Institut Straumann AG). Surface roughness, surface topography, and elemental and surface composition were investigated with optical profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The presence and size of Ti hydride (TiH) needles were determined on metallographic sections. Depth profiling was obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) to determine possible enrichment of an alloying element at the implant surface. Results The mean arithmetic deviation roughness (Sa), of TG4AO was 0.80 μm. The Sa of TG4AO was 1.22 μm, and the Sa of TG4AO was 1.59 μm. The difference between the groups was significant (P<.001). TG23AE and TG4AE displayed a macrotexture and microtexture with pores; TG4AO showed a 3-to 12-μm canyon-like structure. The surface and subsurface compositions were as follows: for TG4AO, αTi and phosphorus-rich anatase; for TG23AE, α-Ti matrix with β-Ti grains; and for TG4AE, α-Ti and δ-TiH2-x. TiH needles were found only on TG4AE; the Ti oxide layer of TG4AO was rough, 3-to 16-μm thick, and porous. The time-of-flight secondary ion mass spectrometry (ToF SIMS) concentration profile of TG23AE did not show enrichment of any alloying element. Conclusions The roughness, topography, and composition of the surfaces were different for all implants tested. Airborne-particle abrasion and subsequent etching was an appropriate treatment for Ti gr 23 alloy implants.

As the demand for esthetics in dentistry has increased over the years, zirconia-based restorations have been successfully used as alternatives to metal-ceramic restorations. A reliable marginal seal is among the factors that are vital to the clinical success of a dental restoration. One advantage of zirconia-based restorations is that the cementation process is generally simpler and more efficient compared to the delivery/cementation of other all-ceramic systems. This article reviews several categories of cement used for the cementation of zirconia restorations: zinc-phosphate cement, glass-ionomer cement (GIC), resin-modified GIC, and composite-resin cement.

Reliability of four groups of ceramic indenter/disc systems was tested using a step-stress accelerated life-testing model. Specimens were fatigued to failure according to three step-stress profiles: light, moderate and aggressive. Group LGC/PFM [heat-pressed leucite glass-ceramic on metal (LGC)/porcelain-fused-to-metal (PFM), disc 1.5-mm thickness] exhibited a lowest reliability and mean-time-to-failure (MTTF), and highest failure rate. At 320-N load, Group Y-TZP/Y-TZP [3 mol-% yttria-stabilised tetragonal zirconia polycrystal (Y-TZP)/Y-TZP, disc 0.6-mm thickness] exhibited a significantly longer MTTF than Group LD/LD [heat-pressed lithium disilicate (LD)/LD, disc 1.5-mm thickness] both at 50,000 and 100,000 cycles, at 90% confidence bounds. Y-TZP indenter and disc of 1.2 mm thickness were used as a control and resulted in no fracture at 320-N load and 150,000 cycles. Zirconia specimens at 0.6-mm thickness performed comparably to 1.5-mm LD and better than 1.5-mm layered PFM specimens in terms of reliability (fracture resistance), MTTF and failure rate.