1,720,993 research outputs found
Comparative analysis on intaglio surface trueness, wear volume loss of antagonist, and fracture resistance of full-contour monolithic zirconia crown for single-visit dentistry under simulated mastication
No full textPURPOSE: This analysis aimed to evaluate the intaglio surface trueness, antagonist’s wear volume loss, and fracture resistance of full-contour crowns of (Y, Nb)-stabilized fully-sintered zirconia (FSZ), 4 mol% or 5 mol% yttria-stabilized partially sintered zirconia (4YZ or 5YZ) with high-speed sintering. MATERIALS AND METHODS: A total of 42 zirconia crowns were separated into three groups: FSZ, 4YZ, and 5YZ (n = 14). The intaglio surface trueness of the crowns was evaluated at the inner surface, occlusal, margin, and axial areas and reported as root-mean-square, positive and negative average deviation. Half of the specimens were aged for 120,000 cycles in the chewing simulator, and the wear volume loss of antagonist was measured. Before and after chewing, the fracture load was measured for each group. The trueness values were analyzed with Welch's ANOVA, and the wear volume loss with the Kruskal-Wallis tests. Effect of the zirconia type and aging on fracture resistance of crowns was tested using two-way ANOVA. RESULTS: The intaglio surface trueness measured at four different areas of the crown was less than 50 µm, regardless of the type of zirconia. No significant P in wear volume loss of antagonists were detected among the groups (P > .05). Both the type of zirconia and aging showed statistically significant effects on fracture resistance (P < .05). CONCLUSION: The full-contour crowns of FSZ as well as 4YZ or 5YZ with high-speed sintering were clinically acceptable, in terms of intaglio surface trueness, antagonist’s wear volume loss, and fracture resistance after simulated mastication
Effect of phytochemical-filled microcapsules with antifungal activity on material properties and dimensional accuracy of denture base resin for three-dimensional printing
Full text linkBackground Studies on the material properties and dimensional accuracy of three-dimensionally (3D) printed denture base containing microcapsules with antifungal phytochemicals are lacking. Methods Two types of phytochemicals (phytoncide A and B) with antifungal activity were microencapsulated. The 3D-printed denture base specimens with minimum and maximum effective concentrations of microcapsules (6 and 8 wt% for phytoncide A; 15 and 25 wt% for phytoncide B) were prepared. The morphological changes of C. albicans on 3D-printed denture base with microcapsules was microscopically observed. The degree of conversion of 3D-printed denture base with microcapsules investigated. The microhardness and flexural strength values were also measured to evaluate the mechanical properties of 3D-printed denture bases. The dimensional accuracy (trueness) of the specimens with microcapsules was measured as root-mean-square values (RMS) for the whole, upper, and side surfaces of the specimens as well as their total height. For the degree of conversion, microhardness, and flexural strength values, the Kruskal-Wallis analysis and a post-hoc comparison using Mann-Whitney U test was performed. For the analysis of trueness (RMS), the one-way analysis of variance and a post-hoc comparison using Tukey's method was conducted (alpha = 0.05). Results At both maximum and minimum effective concentrations of microcapsules, cell surface disruption or membrane breakdown of fungal cells were observed in the specimens. The groups with microcapsules (both phytoncide A- and B-filled) showed significantly lower microhardness and elastic modulus values than the control group (all, P = 0.001). For the trueness, all the RMS values of the whole, upper, and side surfaces of the specimens with microcapsules were less than 100 mu m, although significantly higher than those without (all, P = 0.001). The mean flexural strength values of the groups with phytoncide A-filled microcapsule were higher than 65 MPa, not statistically different from that of the control group (all, P > 0.05). However, the groups with phytoncide B-filled microcapsules showed significantly lower values than the control (all, P = 0.001). Conclusions Within the limitations of this in-vitro study, the 3D-printed denture base containing 6 wt% of phytoncide A-filled microcapsules was clinically acceptable in terms of antifungal activity, dimensional accuracy, and flexural strength.N
Tissue surface adaptation of CAD-CAM maxillary and mandibular complete denture bases manufactured by digital light processing: A clinical study
No full textStatement of problem. Clinical studies evaluating the tissue surface adaptation of complete denture bases fabricated by digital light processing (DLP) are lacking. Purpose. The purpose of this clinical study was to assess the tissue surface adaptation of complete denture bases generated by the DLP technique and to compare the adaptation with that of denture bases manufactured by 5-axis milling (MIL) and pack-and-press (PAP) method. Material and methods. A total of 9 participants with 12 edentulous arches (7 maxillary and 5 mandibular) were included in this study. For each edentulous arch, the complete denture bases with occlusion rims were prepared by 3 different techniques (PAP, MIL, and DLP). A virtual denture base with occlusion rim was designed by means of a digital subtraction tool and served to fabricate the DLP and MIL denture bases. The complete denture bases were placed intraorally with an indicator applied to the intaglio surfaces. The thickness of the indicator was measured within the denture-bearing areas and anatomic landmarks of the edentulous arch to obtain the absolute tissue surface adaptation (ATA) value. The relative tissue surface adaptation (RTA) value was calculated from the differences between the ATA values of DLP or MIL techniques and those of the PAP technique. The Kruskal-Wallis test and the McNemar test were used for statistical analysis (alpha=.05). Results. No statistically significant differences were found among the 3 denture base fabrication techniques with respect to the ATA values of either arch (P.05). Conclusions. The DLP and MIL denture bases demonstrated clinically acceptable tissue surface adaptation to both edentulous the maxilla and mandible. The DLP denture base was likely to exhibit intimate tissue adaptation in the stress-bearing areas of maxillary arches compared with the PAP denture base. The maxillary MIL denture base was likely to exhibit small gaps between the supporting tissue and denture base. Both DLP and MIL mandibular denture bases were likely to show intimate adaptation on the lingual slope compared with the PAP base.11Nsciescopu
Effects of ultrasonic scaling on the optical properties and surface characteristics of highly translucent CAD/CAM ceramic restorative materials: An in vitro study
No full textEsthetic restorations using highly translucent ceramics powered by chairside digital dentistry are becoming popular. The purpose of this in vitro study was to investigate the impact of ultrasonic scaling on the optical and surface properties of highly translucent ceramic materials for digital dentistry. A resin nanoceramic (Lava Ultimate; LU), dual-network ceramic (Vita Enamic; VE), feldspathic ceramic (Vitablocs Mark II; VM), lithium disilicate ceramic (IPS e.max CAD; EX), and high-translucency monolithic zirconia (Rainbow Shine-T; MZ) were evaluated. All specimens were subjected to ultrasonic scaling, and the following data were obtained before and after scaling: color change (Delta E-00), translucency parameter, surface gloss, surface roughness, and superficial topography. One-way analysis of variance (ANOVA), repeated-measures ANOVA, and two-way ANOVA were used for intergroup comparisons (all alpha = 0.05). The mean Delta E-00 values were 0.243, 0.48, 1.591, 0.143, and 4.466 for LU, VE, VM, EX, and MZ, respectively, with statistically significant differences among the materials. With regard to Commission Internationale de Itclairage (CIE) L*, a*, and b* values, VE, VM, and MZ showed significantly decreased L* values relative to the baseline values. Moreover, MZ showed a significantly increased a* value and a significantly decreased b* value after scaling. Ultrasonic scaling also resulted in significant changes in the surface gloss of the LU, VE, VM, and MZ specimens. Micrographs showed scrapes and surface deterioration after scaling. For all materials, the translucency parameter and the surface roughness showed no significant differences between specimens that were subjected to scaling and those that were not. These findings suggest that ultrasonic scaling MARKEDLY affects the optical properties and surface characteristics of highly translucent computer-aided design and computer-aided manufacturing (CAD/CAM) ceramics. The findings can aid restorative dentists in the selection of appropriate materials and motivate periodontists for performing scaling procedures with due consideration of restorations in esthetically demanding areas.Y
Wear of 3D printed and CAD/CAM milled interim resin materials after chewing simulation
No full textPURPOSE. The purpose of this in vitro study was to investigate the wear resistance and surface roughness of three interim resin materials, which were subjected to chewing simulation. MATERIALS AND METHODS. Three interim resin materials were evaluated: (1) three-dimensional (3D) printed (digital light processing type), (2) computer-aided design and computer-aided manufacturing (CAD/CAM) milled, and (3) conventional polymethyl methacrylate interim resin materials. A total of 48 substrate specimens were prepared. The specimens were divided into two subgroups and subjected to 30,000 or 60,000 cycles of chewing simulation (n = 8). The wear volume loss and surface roughness of the materials were compared. Statistical analysis was performed using oneway analysis of variance and Tukey's post-hoc test (alpha=.05). RESULTS. The mean +/- standard deviation values of wear volume loss (in mm(3)) against the metal abrader after 60,000 cycles were 0.10 +/- 0.01 for the 3D printed resin, 0.21 +/- 0.02 for the milled resin, and 0.44 +/- 0.01 for the conventional resin. Statistically significant differences among volume losses were found in the order of 3D printed, milled, and conventional interim materials (P <.001). After 60,000 cycles of simulated chewing, the mean surface roughness (Ra; mu m) values for 3D printed, milled, and conventional materials were 0.59 +/- 0.06, 1.27 +/- 0.49, and 1.64 +/- 0.44, respectively. A significant difference was found in the Ra value between 3D printed and conventional materials (P =.01). CONCLUSION. The interim restorative materials for additive and subtractive manufacturing digital technologies exhibited less wear volume loss than the conventional interim resin. The 3D printed interim restorative material showed a smoother surface than the conventional interim material after simulated chewing.Y
Effect of a macroscopic groove on bone response and implant stability
No full textObjectives: The aim of this study was to investigate the effect of a macroscopic groove on
bone response and implant stability during the early stages of healing using a rabbit tibia
model.
Materials and methods: Anodized titanium implants with (n¼24) and without (n¼24)
macroscopic grooves were prepared. A total of 12 rabbits were used and each received four
implants: six rabbits with implants with macroscopic grooves (test group) and six rabbits
with implants without macroscopic groves (control group). Histomorphometry, resonance
frequency, and removal torque value were evaluated 2 and 6 weeks post-implant-insertion.
Results: At 2 and 6 weeks, there was no significant difference between the two groups in
the percentage of bone-to-implant contact (P40.05). At 6 weeks, the test group had
significantly higher implant stability quotient values than the control group (Po0.05). At 2
and 6 weeks, implants with grooves showed a significantly greater resistance to reverse
torque than control implants (Po0.05).
Conclusion: The groove on the oxidized titanium surface may increase both resistance to
shear load and adhesion at the bone–implant interface. A geometric feature such as a
macroscopic groove may facilitate osseointegration and increase implant stability in various
clinical conditions. Further studies are required to confirm whether the improvement in
implant stability will enhance treatment success in humans
The effect of surface material, roughness and wettability on the adhesion and proliferation of Streptococcus gordonii, Fusobacterium nucleatum and Porphyromonas gingivalis☆
No full textBackground/purpose: Dental implants are inevitably exposed to bacteria in oral cavity. Understanding the colonization of bacteria on implant surface is necessary to prevent bacteria-related inflammation surrounding dental implants. The purpose of this study was to investigate the effect of surface properties on biofilm formation on the implant surface. Materials and methods: One early colonizer, Streptococcus gordonii (S. gordonii), and two late colonizers, Fusobacterium nucleatum (F. nucleatum) and Porphyromonas gingivalis (P. gingivalis), were grown on the titanium and zirconia surfaces with two types of surface roughness for 24 and 72 h. Each bacterial biofilm on specimens was quantified using crystal violet assay and observed by scanning electron microscopy. Results: S. gordonii formed more biofilm on the titanium surface than zirconia at the same roughness and more biofilm on the rough surface than smooth one of the same materials at 24 and 72 h of incubation. F. nucleatum adhered on all the surfaces at 24 h and proliferated actively on the surfaces except smooth zirconia at 72 h. P. gingivalis proliferated vigorously on the surfaces at 72 h while it scarcely adhered at 24 h. There was no consistent correlation between contact angle and biofilm formation of the three bacteria. Conclusion: The three bacteria proliferated most on the rough titanium surface and least on the smooth zirconia surface. In addition, the proliferation was affected by the bacterial species as well as the surface properties
Antibacterial activity and biocompatibility of silver coating via aerosol deposition on titanium and zirconia surfaces
Full text linkAbstract Purpose The purpose of this in vitro study was to investigate the antibacterial effect and biocompatibility of silver coatings via aerosol deposition on titanium and zirconia surfaces. Methods The surfaces of titanium and zirconia specimens were polished and coated with silver via aerosol deposition. After silver coating, the elemental composition, surface roughness and amount of silver released from the coated surfaces were measured. The bacterial growth on the silver-coated surfaces was investigated via crystal violet assay after incubation with Streptococcus gordonii for 24 h, Fusobacterium nucleatum for 72 h and Porphyromonas gingivalis for 48 h. Human gingival fibroblasts and mouse preosteoblasts were also cultured on the silver-coated specimens to examine the biocompatibility of the coating. Results After silver coating via aerosol deposition, the surface roughness increased significantly, and the released silver ranged from 0.067 to 0.110 ppm. The tested bacteria formed significantly less biofilm on the silver-coated titanium surfaces than on the uncoated titanium surfaces. In contrast, biofilm formation on the silver-coated zirconia surfaces was greater than that on the uncoated zirconia surfaces. Human gingival fibroblasts and mouse preosteoblasts proliferated on the silver-coated surfaces without significant differences from the uncoated surfaces. Conclusions Silver coating via aerosol deposition provided an antibacterial effect against oral bacteria on titanium surfaces, whereas it promoted more bacterial growth on zirconia surfaces. The proliferation of fibroblasts and osteoblasts was not significantly affected by the silver coating on both titanium and zirconia surfaces
Analysis of surface characteristics of (Y, Nb)- TZP after finishing and polishing
No full textPURPOSE. This in vitro study aimed to evaluate the surface characteristics of a full veneer crown fabricated chairside (CS) from a (Y, Nb)-TZP zirconia block in response to conventional zirconia grinding and polishing. MATERIALS AND METHODS. Zirconia crowns (n = 40) were first prepared and divided into two groups of materials: Labside (LS) and CS, after which each specimen went through a five-step grinding and polishing procedure. Following each surface treatment, surface characteristics were analyzed using confocal laser microscopy (CLSM), average surface roughness (Ra) values were processed from the profile data through Gaussian filtering, and X-ray diffraction pattern analysis was performed to evaluate the monoclinic (M) phase content. Then, a representative specimen was selected for field-emission scanning electron microscopy (FE-SEM), followed by a final analysis of the roughness and X-ray diffraction of the specimens using the independent t-test and repeated measures analysis of variance (RM-ANOVA). RESULTS. In every group, polishing significantly reduced the Ra values (P < .001). There was no significant difference in Ra between the polished state CS and LS. Furthermore, CLSM and FE-SEM investigations revealed that even though grain exposure was visible in CS specimens throughout the as-delivered and ground states, the exposure was reduced after polishing. Moreover, while no phase transformation was visible in the LS, phase transformation was visible in CS after every surface treatment, with the M phase content of the CS group showing a significant reduction after polishing (P < .001). CONCLUSION. Within the limits of this study, clinically acceptable level of surface finishing of (Y, Nb)-TZP can be achieved after conventional zirconia polishing sequence. [J Adv Prosthodont 2022;14:335-45]Y
Topographical and crystalline change on surface by sandblasting improve flexural and shear bond strength of niobia-modified yttria-stabilized tetragonal zirconia polycrystal
No full textThis study aimed to investigate the effects of sandblasting on the physical properties and bond strength of two types of translucent zirconia: niobium-oxide-containing yttria-stabilized tetragonal zirconia polycrystals ((Y, Nb)-TZP) and 5 mol% yttria-partially stabilized zirconia (5Y-PSZ). Fully sintered disc specimens were either sandblasted with 125 μm alumina particles or left as-sintered. Surface roughness, crystal phase compositions, and surface morphology were explored. Biaxial flexural strength (n=10) and shear bond strength (SBS) (n=12) were evaluated, including thermocycling conditions. Results indicated a decrease in flexural strength of 5Y-PSZ from 601 to 303 MPa upon sandblasting, while (Y, Nb)-TZP improved from 458 to 544 MPa. Both materials significantly increased SBS after sandblasting (p<0.001). After thermocycling, (Y, Nb)-TZP maintained superior SBS (14.3 MPa) compared to 5Y-PSZ (11.3 MPa) (p<0.001). The study concludes that (Y, Nb)-TZP is preferable for sandblasting applications, particularly for achieving durable bonding without compromising flexural strength.N
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