936 resultados para Semiconducting II-VI materials


Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVES: To evaluate the pattern of tissue remodeling after maxillary sinus floor elevation using the transalveolar osteotome technique with or without utilizing grafting materials. METHODS: During the period of 2000-2005, 252 Straumann dental implants were inserted using the transalveolar sinus floor elevation technique in a group of 181 patients. For 88 or 35% of those implants, deproteinized bovine bone mineral with a particle size of 0.25-1 mm was used as the grafting material, but for the remaining 164 implants, no grafting material was utilized. Periapical radiographs were obtained with a paralleling technique and digitized. Two investigators, who were blinded to whether grafting material was used or not, subsequently evaluated the pattern of tissue remodeling. RESULTS: The mean residual bone height was 7.5 mm (SD 2.2 mm), ranging from 2 to 12.7 mm. The mean residual bone height for implants placed with grafting material (6.4 mm) was significantly less compared with the implants installed without grafting material (8.1 mm). The implants penetrated on average 3.1 mm (SD 1.7 mm) into the sinus cavity. The measured mean radiographic bone gain using the transalveolar technique without grafting material was significantly less, 1.7 mm (SD 2 mm) compared with a mean bone gain of 4.1 mm (SD 2.4 mm), when grafting material was used. Furthermore, the probability of gaining 2 mm or more of new bone was 39.1% when no grafting material was used. The probability increased to 77.9% when the implants were installed with grafting material. CONCLUSION: When the transalveolar sinus floor elevation was performed without utilizing grafting material, only a moderate gain of new bone could be detected mesial and distal to the implants. On the other hand, when grafting material was used, a substantial gain of new bone was usually seen on the radiographs.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Three hundred botanically identified plant materials have been extracted with 50% ethanol and the extracts put through a wide biological screen. These include tests for antibacterial, anticancer, antifertility, antifungal, anthelminthic, antiprotozoal, antiviral and pharmacological activities. Biological activities have been confirmed in fractions of fifty-six of these extracts.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Two hundred and ninety eight botanically identified plant materials have been tested as 50% ethanol extracts, for a wide variety of biological activities including antifertility, anticancer, chemotherapeutic and pharmacological activities. Biological activities been confirmed in fractions of 84 of these extracts.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE To clinically evaluate the treatment of Miller Class I and II multiple adjacent gingival recessions using the modified coronally advanced tunnel technique combined with a newly developed bioresorbable collagen matrix of porcine origin. METHOD AND MATERIALS Eight healthy patients exhibiting at least three multiple Miller Class I and II multiple adjacent gingival recessions (a total of 42 recessions) were consecutively treated by means of the modified coronally advanced tunnel technique and collagen matrix. The following clinical parameters were assessed at baseline and 12 months postoperatively: full mouth plaque score (FMPS), full mouth bleeding score (FMBS), probing depth (PD), recession depth (RD), recession width (RW), keratinized tissue thickness (KTT), and keratinized tissue width (KTW). The primary outcome variable was complete root coverage. RESULTS Neither allergic reactions nor soft tissue irritations or matrix exfoliations occurred. Postoperative pain and discomfort were reported to be low, and patient acceptance was generally high. At 12 months, complete root coverage was obtained in 2 out of the 8 patients and 30 of the 42 recessions (71%). CONCLUSION Within their limits, the present results indicate that treatment of Miller Class I and II multiple adjacent gingival recessions by means of the modified coronally advanced tunnel technique and collagen matrix may result in statistically and clinically significant complete root coverage. Further studies are warranted to evaluate the performance of collagen matrix compared with connective tissue grafts and other soft tissue grafts.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Purpose: To investigate the bond strength to dentin of two recent resin-ceramic materials for computer-aided design/computer-aided manufacturing (CAD/CAM) after 24 hours and after six months storage. Methods and Materials: Ninety cylinders were milled out of Lava Ultimate (3M ESPE) and 90 cylinders out of VITA ENAMIC (VITA Zahnfabrik) (dimension of cylinders: ∅=3.6 mm, h=2 mm). All Lava Ultimate cylinders were sandblasted (aluminium oxide, grain size: 27 μm) and cleaned with ethanol, whereas all VITA ENAMIC cylinders were acid-etched (5% hydrofluoric acid) and cleaned with water-spray. According to the three groups of cements used, the cylinders (n=30/resin-ceramic material) were further pretreated with 1) Scotchbond Universal for RelyX Ultimate (3M ESPE), 2) CLEARFIL Ceramic Primer for PANAVIA F2.0 (Kuraray), or 3) no further pretreatment for Ketac Cem Plus (3M ESPE). The cylinders were then bonded to ground human dentin specimens with 1) Scotchbond Universal and RelyX Ultimate (light-cured), 2) ED PRIMER II and PANAVIA F2.0 (light-cured), or 3) no adhesive system; Ketac Cem Plus (self-cured). Shear bond strength (SBS) was measured after 24 hours for 15 specimens/group and after six months (37°C, 100% humidity) for the other 15 specimens/group. SBS-values were statistically analysed with nonparametric ANOVA followed by exact Wilcoxon rank sum tests (α=0.05). Results: SBS of the two resin-ceramic materials and the three cements after 24 hours and after six months storage are shown in Figure 1. The statistical analysis showed that the duration of storage had a significant effect on SBS of Lava Ultimate for all three cements but had no significant effect on SBS of VITA ENAMIC. For Lava Ultimate SBS-values were (MPa; medians after 24 hours/six months): 13.5/22.5 (p=0.04) for RelyX Ultimate, 11.4/5.8 (p=0.0006) for PANAVIA F2.0, and 0.34/0.09 (p=0.04) for Ketac Cem Plus (Fig. 1). For VITA ENAMIC SBS-values were (MPa; medians after 24 hours/six months): 16.0/21.2 (p=0.10) for RelyX Ultimate, 11.4/14.4 (p=0.06) for PANAVIA F2.0, and 0.43/0.41 (p=0.32) for Ketac Cem Plus (Fig. 1). After 24 hours, there was no significant difference in SBS between Lava Ultimate and VITA ENAMIC for all three cements (p≥0.37). After six months, there was no significant difference in SBS between Lava Ultimate and VITA ENAMIC for RelyX Ultimate and Ketac Cem Plus (p≥0.07) whereas for PANAVIA F2.0, SBS was significantly lower for Lava Ultimate than for VITA ENAMIC (p<0.0001). Conclusion: SBS of Lava Ultimate was more affected by six months storage and by the cement used than was VITA ENAMIC.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVES To clinically evaluate the healing of mandibular Miller Class I and II isolated gingival recessions treated with the modified coronally advanced tunnel (MCAT) in conjunction with an enamel matrix derivative (EMD) and subepithelial connective tissue graft (SCTG). METHOD AND MATERIALS Sixteen healthy patients (13 women and 3 men) exhibiting one isolated mandibular Miller Class I and II gingival recessions of a depth of ≥ 3 mm, were consecutively treated with the MCAT in conjunction with EMD and SCTG. Treatment outcomes were assessed at baseline and at 12 months postoperatively. The primary outcome variable was complete root coverage (CRC) (eg, 100% root coverage). RESULTS Postoperative pain and discomfort were low and no complications such as postoperative bleeding, allergic reactions, abscesses, or loss of SCTG were observed. At 12 months, statistically significant (P < .0001) root coverage was obtained in all 16 defects. CRC was measured in 12 out of the 16 cases (75%) while in the remaining 4 defects root coverage amounted to 90% (in two cases) and 80% (in two cases), respectively. Mean root coverage was 96.25%. Mean keratinized tissue width increased from 1.98 ± 0.8 mm at baseline to 2.5 ± 0.9 mm (P < .0001) at 12 months, while mean probing depth did not show any statistically significant changes (ie, 1.9 ± 0.3 mm at baseline vs 1.8 ± 0.2 mm at 12 months). CONCLUSION Within their limits, the present results indicate that the described treatment approach may lead to predictable root coverage of isolated mandibular Miller Class I and II gingival recessions.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Three-dimensional oxalate-based {[Ru(bpy)3][Cu2xNi2(1-x)(ox)3]}n (0≤ x ≤ 1, ox = C2O42-, bpy = 2,2‘bipyridine) were synthesized. The structure was determined for x = 1 by X-ray diffraction on single crystal. The compound crystallizes in the cubic space group P4132. It shows a three-dimensional 10-gon 3-connected (10,3) anionic network where copper(II) has an unusual tris(bischelated) environment. X-ray powder diffraction patterns and their Rietveld refinement show that all the compounds along the series are isostructural and single-phased. According to X-ray absorption spectroscopy, copper(II) and nickel(II) have an octahedral environment, respectively elongated and trigonally distorted. As shown by natural circular dichroism, the optically active forms of {[Ru(bpy)3][CuxNi2(1-x)(ox)3]}n are obtained starting from resolved Δ- or Λ-[Ru(bpy)3]2+. The Curie−Weiss temperatures range between −55 (x = 1) and −150 K (x = 0). The antiferromagnetic exchange interaction thus decreases when the copper contents increases in agreement with the crystallographic structure of the compounds and the electronic structure of the metal ions. At low temperature, the compounds exhibit complex long-range ordered magnetic behavior.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Compounds [NH3(CH2)4NH3]Cu3(hedp)2·2H2O (1) and [NH3(CH2)3NH3]Cu3(hedp)2·3.5H2O (2), where hedp represents 1-hydroxyethylidenediphosphonate, exhibit two-dimensional structures closely related to each other. The anionic layers with composition {Cu3(hedp)2}n2n- contain four- and eight-membered rings assembled from vertex-sharing {CuO4} units and {CPO3} tetrahedra. The protonated diamines and lattice water fill the interlayer spaces. Crystal data for 2:  space group P1̄, a = 8.0315(4), b = 11.3713(6), c = 13.3117(7) Å, α = 97.122(1), β = 103.187(1), γ = 108.668(1)°, V = 1095.5(1) Å3, Z = 2. Magnetic properties of the two compounds have been investigated. Both show typical metamagnetic behaviors at low temperature. The critical field at which the antiferromagnetic ground-state switches to a ferrimagnetic state is ∼48 Oe for 1 and 185 Oe for 2 at about 2 K.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported fixed dental prostheses (FDPs) and to describe the incidence of biological, technical and esthetic complications. METHODS Medline (PubMed), Embase and Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006-2013) were performed for clinical studies focusing on tooth-supported FDPs with a mean follow-up of at least 3 years. This was complemented by an additional hand search and the inclusion of 10 studies from a previous systematic review [1]. Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. RESULTS Forty studies reporting on 1796 metal-ceramic and 1110 all-ceramic FDPs fulfilled the inclusion criteria. Meta-analysis of the included studies indicated an estimated 5-year survival rate of metal-ceramic FDPs of 94.4% (95% CI: 91.2-96.5%). The estimated survival rate of reinforced glass ceramic FDPs was 89.1% (95% CI: 80.4-94.0%), the survival rate of glass-infiltrated alumina FDPs was 86.2% (95% CI: 69.3-94.2%) and the survival rate of densely sintered zirconia FDPs was 90.4% (95% CI: 84.8-94.0%) in 5 years of function. Even though the survival rate of all-ceramic FDPs was lower than for metal-ceramic FDPs, the differences did not reach statistical significance except for the glass-infiltrated alumina FDPs (p=0.05). A significantly higher incidence of caries in abutment teeth was observed for densely sintered zirconia FDPs compared to metal-ceramic FDPs. Significantly more framework fractures were reported for reinforced glass ceramic FDPs (8.0%) and glass-infiltrated alumina FDPs (12.9%) compared to metal-ceramic FDPs (0.6%) and densely sintered zirconia FDPs (1.9%) in 5 years in function. However, the incidence of ceramic fractures and loss of retention was significantly (p=0.018 and 0.028 respectively) higher for densely sintered zirconia FDPs compared to all other types of FDPs. CONCLUSIONS Survival rates of all types of all-ceramic FDPs were lower than those reported for metal-ceramic FDPs. The incidence of framework fractures was significantly higher for reinforced glass ceramic FDPs and infiltrated glass ceramic FDPs, and the incidence for ceramic fractures and loss of retention was significantly higher for densely sintered zirconia FDPs compared to metal-ceramic FDPs.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Leipzig, Univ., Diss. 1888

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A large family of bifunctional 1,2,4-triazole molecular tectons (tr) has been explored for engineering molybdenum(VI) oxide hybrid solids. Specifically, tr ligands bearing auxiliary basic or acidic groups were of the type amine, pyrazole, 1H-tetrazole, and 1,2,4-triazole. The organically templated molybdenum(VI) oxide solids with the general compositions [MoO3(tr)], [Mo2O6(tr)], and [Mo2O6(tr)(H2O)2] were prepared under mild hydrothermal conditions or by refluxing in water. Their crystal structures consist of zigzag chains, ribbons, or helixes of alternating cis-{MoO4N2} or {MoO5N} polyhedra stapled by short [N–N]-tr bridges that for bitriazole ligands convert the motifs into 2D or 3D frameworks. The high thermal (235–350 °C) and chemical stability observed for the materials makes them promising for catalytic applications. The molybdenum(VI) oxide hybrids were successfully explored as versatile oxidation catalysts with tert-butyl hydroperoxide (TBHP) or aqueous H2O2 as an oxygen source, at 70 °C. Catalytic performances were influenced by the different acidic–basic properties and steric hindrances of coordinating organic ligands as well as the structural dimensionality of the hybrid.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE To assess the maxillary second molar (M2) and third molar (M3) inclination following orthodontic treatment of Class II subdivision malocclusion with unilateral maxillary first molar (M1) extraction. MATERIALS AND METHODS Panoramic radiographs of 21 Class II subdivision adolescents (eight boys, 13 girls; mean age, 12.8 years; standard deviation, 1.7 years) before treatment, after treatment with extraction of one maxillary first molar and Begg appliances and after at least 1.8 years in retention were retrospectively collected from a private practice. M2 and M3 inclination angles (M2/ITP, M2/IOP, M3/ITP, M3/IOP), constructed by intertuberosity (ITP) and interorbital planes (IOP), were calculated for the extracted and nonextracted segments. Random effects regression analysis was performed to evaluate the effect on the molar angulation of extraction, time, and gender after adjusting for baseline measurements. RESULTS Time and extraction status were significant predictors for M2 angulation. M2/ITP and M2/IOP decreased by 4.04 (95% confidence interval [CI]: -6.93, 1.16; P  =  .001) and 3.67 (95% CI: -6.76, -0.58; P  =  .020) in the extraction group compared to the nonextraction group after adjusting for time and gender. The adjusted analysis showed that extraction was the only predictor for M3 angulation that reached statistical significance. M3 mesial inclination increased by 7.38° (95% CI: -11.2, -3.54; P < .001) and 7.33° (95% CI: -11.48, -3.19; P  =  .001). CONCLUSIONS M2 and M3 uprighting significantly improved in the extraction side after orthodontic treatment with unilateral maxillary M1 extraction. There was a significant increase in mesial tipping of maxillary second molar crowns over time.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE To evaluate the long-term effects of asymmetrical maxillary first molar (M1) extraction in Class II subdivision treatment. MATERIALS AND METHODS Records of 20 Class II subdivision whites (7 boys, 13 girls; mean age, 13.0 years; SD, 1.7 years) consecutively treated with the Begg technique and M1 extraction, and 15 untreated asymmetrical Class II adolescents (4 boys, 11 girls; mean age, 12.2 years; SD, 1.3 years) were examined in this study. Cephalometric analysis and PAR assessment were carried out before treatment (T1), after treatment (T2), and on average 2.5 years posttreatment (T3) for the treatment group, and at similar time points and average follow-up of 1.8 years for the controls. RESULTS The adjusted analysis indicated that the maxillary incisors were 2.3 mm more retracted in relation to A-Pog between T1 and T3 (β  =  2.31; 95% CI; 0.76, 3.87), whereas the mandibular incisors were 1.3 mm more protracted (β  =  1.34; 95% CI; 0.09, 2.59), and 5.9° more proclined to the mandibular plane (β  =  5.92; 95% CI; 1.43, 10.41) compared with controls. The lower lip appeared 1.4 mm more protrusive relative to the subnasale-soft tissue-Pog line throughout the observation period in the treated adolescents (β  =  1.43; 95% CI; 0.18, 2.67). There was a significant PAR score reduction over the entire follow-up period in the molar extraction group (β  =  -6.73; 95% CI; -10.7, -2.7). At T2, 65% of the subjects had maxillary midlines perfectly aligned with the face. CONCLUSIONS Unilateral M1 extraction in asymmetrical Class II cases may lead to favorable occlusal outcomes in the long term without harming the midline esthetics and soft tissue profile.