Ohtonen J.,University of Turku |
Lassila L.V.J.,University of Turku |
Lassila L.V.J.,City of Kotka Municipal Health Center |
Sailynoja E.,Turku Clinical Biomaterials Center |
And 4 more authors.
Strength, Fracture and Complexity | Year: 2016
The aim of this study was to investigate the mechanical properties of fiber reinforced composite (FRC) wires with different polymer matrices and compare them with steel wires commonly used in orthodontic retention. Eight groups of the FRC wires (continuous unidirectional E-glass) and a control group of steel metal Penta One 0.0215′′ were tested with a 3-point bending test. The FRC wire groups consisted of two thicknesses of fiber rovings (300-Tex and 600-Tex) which were impregnated with a light-curing monomer resin system of bis-GMA/PMMA or bis-Mepp/dimetacrylate/prosphoric ester monomer. The bending was continued until breakage of the specimen or to the strain of 3 mm using a span length of 10 mm and cross-head speed 1.00 mm/minute. The data were analysed using analysis of variance (ANOVA). The maximum load values of the FRC wire groups varied between 1.3 and 20.0 N, and the control group was 2.4 N. Specimens of 600-Tex groups had considerably higher load values than 300-Tex groups. The load value of the control steel group was close to the load value of in the 300-Tex groups. Bis-GMA/PMMA impregnated FRC demonstrated higher values of maximum load than bis-Mepp/dimethacrylate/prosphoric ester monomere resin impregnated FRC.
Meretoja V.V.,University of Turku |
Meretoja V.V.,Turku Clinical Biomaterials Center |
Tirri T.,University of Turku |
Tirri T.,Turku Clinical Biomaterials Center |
And 4 more authors.
Clinical Oral Implants Research | Year: 2014
Objectives: To characterize biological response to subcutaneously implanted macroporous poly(ε-caprolactone/D,L-lactide)-based scaffolds, and to evaluate the effect of bioactive glass (BAG) filler and osteogenic cells to the tissue response and ectopic bone formation. Material and methods: In the first part of this study, six different scaffold types were screened in a rat subcutaneous implantation model. The polymer scaffolds with 70/30 caprolactone/lactide ratio and corresponding composites with < 45 μm BAG filler size were chosen for the further ectopic bone formation assay. The scaffolds were loaded with differentiating bone marrow stromal cells and implanted subcutaneously in syngeneic rats. Results: With plain scaffolds, only mild foreign body reaction with no signs of gross inflammation was observed after 4 weeks of implantation. Furthermore, the scaffolds were fully invaded by well-vascularized soft connective tissue. Overall, all the tested scaffold types showed an appropriate host response. With cell-seeded scaffolds, several loci of immature mineralizing tissue and small amounts of mature bone were observed after 4 weeks. The incidence of mature bone formation was two and four in polymer scaffolds and composites, respectively (n = 8). After twelve weeks, mature bone was observed in only one polymer scaffold but in seven composites (n = 8). Excluding bone formation, the host response was considered similar to that with cell-free scaffolds. Conclusions: Plain scaffolds supported the ingrowth of well-vascularized fibroconnective tissue. Furthermore, cell seeded composites with BAG filler showed enhanced ectopic bone formation in comparison with corresponding neat polymer scaffolds. © 2012 John Wiley & Sons A/S.
Uusitalo E.,University of Turku |
Varrela J.,University of Turku |
Lassila L.,Turku Clinical Biomaterials Center |
Vallittu P.K.,University of Turku |
Vallittu P.K.,Turku Clinical Biomaterials Center
BioMed Research International | Year: 2016
Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n = 5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p < 0.05). The increase of the specimen thickness decreased light transmission in all groups (p < 0.005), and moist specimens attenuated light less than air-dried specimens in all thicknesses (p < 0.05). EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness) (p < 0.05). Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm) and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm). Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert's law. © 2016 E. Uusitalo et al.
Wilson T.,University of Turku |
Wilson T.,Turku Clinical Biomaterials Center |
Stark C.,University of Turku |
Holmbom J.,University of Turku |
And 5 more authors.
Journal of Tissue Engineering | Year: 2010
The fate of intraperitoneally injected or implanted male rat bone marrow-derived stromal cells inside female sibling host animals was traced using Y-chromosome-sensitive PCR. When injected intraperitoneally, Y-chromosome-positive cells were found in all studied organs: heartmuscle, lung, thymus, liver, spleen, kidney, skin, and femoral bone marrow with a few exceptions regardless of whether they had gone through osteogenic differentiation or not. In the implant experiments, expanded donor cells were seeded on poly(lactide-co-glycolide) scaffolds and grown under three different conditions (no additives, in osteogenic media for one or two weeks) prior to implantation into corticomedullar femoral defects. Although the impact of osteogenic in vitro cell differentiation on cell migration was more obvious in the implantation experiments than in the intraperitoneal experiments, the donor cells stay alive when injected intraperitoneally or grown in an implant and migrate inside the host. However, when the implants contained bioactive glass, no signs of Y-chromosomal DNA were observed in all studied organs including the implants indicating that the cells had been eliminated. © 2010 TimothyWilson et al.
Sulaiman T.A.,University of Turku |
Sulaiman T.A.,Turku Clinical Biomaterials Center |
Sulaiman T.A.,University of North Carolina at Chapel Hill |
Abdulmajeed A.A.,University of Turku |
And 8 more authors.
Dental Materials Journal | Year: 2015
The effect of staining and vacuum sintering on optical properties and the bi-axial flexural strength of partially and fully stabilized monolithic zirconia (PSZ, FSZ) were evaluated. Disc-shaped specimens divided into three subgroups (n=15): non-stained, stained and non-stained with vacuum sintering. After staining and sintering, optical properties were evaluated using a reflection spectrophotometer and bi-axial flexural strength was tested using the piston-on-three balls technique. Statistical analysis was performed using multivariate analysis of variance (MANOVA) followed by post-hoc Tukey’s tests (p<0.05). Staining decreased translucency parameter (TP) values of FSZ (p<0.05). Sintering under vacuum enhanced TP values for PSZ (p<0.05). Staining enhanced surface gloss for both types of zirconia (p<0.05). Staining increased bi-axial flexural strength of FSZ (p<0.05), while it decreased the strength of PSZ (p<0.05). Sintering under vacuum provided minimal benefits with either type of zirconia. © 2015, Japanese Society for Dental Materials and Devices. All rights reserved.