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1.
Mireia Haro Adánez Hironobu Nishihara Wael Att 《Journal of prosthodontic research》2018,62(4):397-406
Purpose
This systematic review evaluates the clinical outcome of zirconia implant-associated survival and success rates, marginal bone loss, and implant–restoration complex integrity.Study selection
Using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, studies including ≥ 10 patients restored with zirconia implants supporting single crowns (SCs) or fixed dental prostheses (FDPs) prior to January 2017 were identified. Primary outcomes were survival rates and marginal bone loss around one and two-piece zirconia implants and the associated implant–restoration complex integrity.Results
1349 studies were selected; after duplicate removal and title screening, 36 remained for full-text screening. 17 studies met the inclusion criteria: 2 randomized controlled clinical studies, 11 prospective clinical studies and 4 retrospective studies. In total, 1704 implants from 1002 patients were evaluated, including 1521 one-piece and 183 two-piece zirconia implants with follow-up between 1 and 7 years.The mean survival rate was 95 % (95 % CI 91–97 %). The overall mean marginal bone loss was 0.98 mm (95 % CI 0.79–1.18); the mean marginal bone loss after 1 year was 0.89 mm (95 % CI 0.60–1.18). No meta-analysis regarding prosthetic outcomes was possible.Conclusions
Survival and marginal bone loss values after one year for one-piece zirconia implants are acceptable, but long-term studies are required to support their clinical use. No particular restoration material can be recommended; this decision is apparently based on clinicians’ preferences.Results from two-piece implants do not provide sufficient data to support their clinical use and no abutment or cementing materials for two-piece zirconia implants can be recommended. 相似文献2.
Satoshi Yamaguchi Renshirou Kani Kazuma Kawakami Manami Tsuji Sayuri Inoue Chunwoo Lee Wakako Kiba Satoshi Imazato 《Dental materials》2018,34(10):1578-1584
Objective
The aim of this study was to evaluate long-term fatigue behavior using an in vitro step-stress accelerated life test (SSALT), and to determine the crack initiation point using in silico finite element analysis for computer-aided designed and manufactured (CAD/CAM) molar crowns fabricated from three commercial CAD/CAM resin composite blocks: Cerasmart (CS; GC, Tokyo, Japan), Katana Avencia Block (KA; Kuraray Noritake Dental, Niigata, Japan), and Shofu Block HC (HC; Shofu, Kyoto, Japan).Methods
Fifty-one mandibular first molar crowns luted on a resin core die were embedded in acrylic resin and covered with a polyvinyl chloride tube. Single compressive tests were performed for five crowns. SSALT was conducted for 36 crowns using three profiles and reliabilities at 120,000 cycles, and a Weibull analysis was conducted. The maximum principal strain of each CAD/CAM resin composite crown model was analyzed by three-dimensional finite element analysis.Results
Fracture loads of CS and KA (3784 ± 144 N and 3915 ± 313 N) were significantly greater than that of HC (2767 ± 227 N) (p < 0.05). Fracture probabilities at 120,000 cycles were 24.6% (CS), 13.7% (KA), and 14.0% (HC). Maximum principal strain was observed around the mesiolingual cusps of CS and KA and the distobuccal cusp of HC.Significance
CAD/CAM resin composite molar crowns containing nano-fillers with a higher fraction of resin matrix exhibited higher fracture loads and greater longevity, suggesting that these crowns could be used as an alternative to ceramic crowns in terms of fatigue behavior. 相似文献3.
Ryota Okada Masaki Asakura Akihiro Ando Hirokazu Kumano Seiji Ban Tatsushi Kawai Jun Takebe 《Journal of prosthodontic research》2018,62(3):287-292
Purpose
The purpose of this study was to ascertain whether computer aided design/computer aided manufacturing (CAD/CAM) composite resin crowns have sufficient strength to withstand the bite force of the molar teeth. The null hypothesis was that the fracture strength of CAD/CAM composite resin crowns is lower than the average maximum bite force of the molar tooth.Methods
The crowns, which shape is the right maxillary first molar, were fabricated using four CAD/CAM blanks made of composite resins (Block HC: HC, KZR-CAD HR: HR, KZR-CAD HR2: HR2, Avencia Block: AVE) and one CAD/CAM blank made of lithium disilicate glass-ceramic (IPS e.max CAD: IPS), which was used as a control. Fracture strength of fabricated crowns bonded to metal abutment and biaxial flexural strength of the materials were evaluated.Results
The results of fracture strength test and biaxial flexural strength test showed different tendencies. The fracture strength of CAD/CAM composite resin crowns except HC ranged from 3.3 kN to 3.9 kN, and was similar to that of IPS (3.3 kN). In contrast, biaxial flexural strength of CAD/CAM composite resins ranged from 175 MPa to 247 MPa, and was significantly lower than that of IPS (360 MPa).Conclusions
All CAD/CAM composite resin crowns studied presented about 3–4 times higher fracture strength than the average maximum bite force of the molar tooth (700–900 N), which result leads to the conclusion that CAD/CAM composite resin crowns would have sufficient strength to withstand the bite force of the molar teeth. 相似文献4.
Vitor Guarçoni de Paula Gerson Bonfante Fabio C. Lorenzoni Paulo G. Coelho Leonardo Rigoldi Bonjardim Vinicius P. Fardin Estevam A. Bonfante 《Dental materials》2019,35(3):511-522
Objective
To evaluate the probability of survival of monolithic and porcelain veneered lithium disilicate crowns comprised by a conventional or modified core when loaded on marginal ridges.Methods
Lithium disilicate molar crowns (n = 30) were fabricated to be tested at mesial and distal marginal ridges and were divided as follows: (1) bilayered crowns with even-thickness 0.5 mm framework (Bi-EV); (2) bilayered crowns with modified core design (Bi-M-lingual collar connected to proximal struts), and: (3) monolithic crowns (MON). After adhesively cemented onto composite-resin prepared replicas, mesial and distal marginal ridges of each crown (n = 20) were individually cyclic loaded in water (30–300 N) with a ceramic indenter at 2 Hz until fracture. The 2-parameter Weibull was used to calculate the probability of survival (reliability) (90% 2-sided confidence bounds) at 1, 2, and 3 million cycles and mean life.Results
The reliability at 1 and 2 million cycles was significantly higher for MON (47% and 19%) compared to Bi-EV (20% and 4%) and Bi-M (17% and 2%). No statistical difference was found between bilayered groups. Only the MON group presented crown survival (7%) at 3 million cycles. The mean life was highest for MON (1.73E + 06), lowest for Bi-M (573,384) and intermediate for Bi-E (619,774). Fractographic analysis showed that the fracture originated at the occlusal surface. The highest reliability was found for MON crowns. The modified framework design did not improve the fatigue life of crowns.Significance
Monolithic lithium disilicate crowns presented higher probability of survival and mean life than bilayered crowns with modified framework design when loaded at marginal ridges. 相似文献5.
Ferhan Egilmez Gulfem Ergun Isil Cekic-Nagas Pekka K. Vallittu Lippo V.J. Lassila 《Journal of prosthodontic research》2018,62(1):65-74
Purpose
The purpose of this study was to determine the flexural strength and Weibull characteristics of different CAD/CAM materials after different in vitro aging conditions.Methods
The specimens were randomly assigned to one of the six in vitro aging conditions: (1) water storage (37 °C, 3 weeks), (2) boiling water (24 h), (3) hydrochloric acid exposure (pH: 1.2, 24 h), (4) autoclave treatment (134 °C, 200 kPa, 12 h), (5) thermal cycling (5000 times, 5–55 °C), (6) cyclic loading (100N, 50,000 cycles). No treatment was applied to the specimens in control group. Three-point bending test was used for the calculation of flexural strength. The reliability of the strength was assessed by Weibull distribution. Surface roughness and topography was examined by coherence scanning interferometry. Evaluated parameters were compared using the Kruskall–Wallis or Mann–Whitney U test.Results
Water storage, autoclave treatment and thermal cycling significantly decreased the flexural strength of all materials (p < 0.05), whereas HCl exposure or cyclic loading did not affect the properties (p > 0.05). Weibull moduli of Cerasmart? and Lava? Ultimate were similar with control. Vita Enamic® exhibited similar Weibull moduli in all aging groups except the HCl treated group (p > 0.05). Ra values of Cerasmart? and Lava? Ultimate were in the range of 0.053–0.088 μm in the aged groups. However Ra results of Vita Enamic® were larger than 0.2 μm.Conclusions
Flexural strength of newly developed restorative CAD/CAM materials was significantly decreased by artificial aging. Cyclic loading or HCl exposure does not affect to the flexural strength and structural reliability of Cerasmart? and Lava? Ultimate. 相似文献6.
Objective
To assess the change in surface roughness of nanohybrid resin composite (Tetric EvoCeram) after antagonist wear against monolithic zirconia and lithium disilicate ceramics through a simulated chewing test using a three-dimensional (3D) profilometer.Methods
A total of 40 Tetric EvoCeram? resin composite specimens against either a Lava? Plus zirconia antagonist (n = 20) or IPS e.max Press lithium disilicate antagonist (n = 20) were prepared for the study. The surface roughness profiles of each resin composite before and after an in-vitro simulated chewing test were analysed using a 3D profilometer and Talymap software. After the simulated chewing, the surface profiles of representative Tetric EvoCeram specimens from each group were analysed using scanning electron microscopy. Independent t-test and paired t-test were used for statistical analysis.Results
For both lithium disilicate and zirconia groups, all surface roughness parameters (Ra, Rt, Sa, Sq,) of Tetric EvoCeram were significantly higher post-chewing compared to pre-chewing (p < 0.05); the post-chewing surface roughness parameters of Tetric EvoCeram for the lithium disilicate group were significantly higher (p < 0.05) than in the zirconia group.Significance
This chewing simulation test showed that Tetric EvoCeram composites exhibited a rougher surface when opposing lithium disilicate ceramic compared to opposing zirconia ceramic. 相似文献7.
Ebrahim Maghami Ehsan Homaei Khalil Farhangdoost Edmond Ho Nang Pow Jukka Pekka Matinlinna James Kit-Hon Tsoi 《Journal of prosthodontic research》2018,62(4):436-442
Purpose
The aim of this study was to investigate and quantify the effect of preparation design parameters on a premolar restored with two different CAD/CAM ceramic crowns by three-dimensional finite element analysis (FEA).Methods
A restored human first premolar was digitized by a micro-CT scanner and a 3D model was created by a medical image processing software (Mimics). Following segmentation, dentine and ceramic were extracted by a surface meshing software (3-matic). Models with different preparation designs with three convergence angles (6°, 12° and 20°) and two preparation heights (3.1 mm and 4.1 mm) were produced. Mesh generation for models was performed in IA-FEMesh software with a lithium disilicate glass ceramic (LD, E = 95.9 GPa) and a polymer-infiltrated ceramic (PIC, E = 30.1 GPa) as the restorative materials. A 5-mm diameter stainless steel hemisphere was employed as an indenter. Twelve models were analyzed numerically in Abaqus?.Results
The results indicated that preparation height was found to be a major factor affecting stress distribution in different components. In all models, the maximum principal stress of the ceramic crowns was found in contact area against the indenter. This stress was lesser in the longer abutment than the shorter one and it was greater for LD ceramic. Convergence angle had limited effect on stress distribution of ceramic crown in all models.Conclusions
The preparation height appeared to play a more important role in the stress distribution of ceramic crown than the convergence angle. 相似文献8.
Catina Prochnow Andressa Borin Venturini Luís Felipe Guilardi Gabriel Kalil Rocha Pereira Thiago Augusto Lima Burgo Marco Cícero Bottino Cornelis Johannes Kleverlaan Luiz Felipe Valandro 《Dental materials》2018,34(9):e255-e263
Objectives
To evaluate the effects of the etching with different hydrofluoric acid (HF) concentrations on the cyclic load-to-failure of machined lithium disilicate crowns cemented to dentin analogue material.Methods
Pairs of dentin analogue prosthetic preparations and lithium disilicate ceramic crowns with simplified and standardized designs were machined (n = 18). The preparations were etched with 10% HF (60 s), followed by primer application. The intaglio surface of the ceramic crowns was treated as follows: non-etched (control, CTRL); or etched for 20 s with different HF concentrations — 3% (HF3), or 5% (HF5), or 10% (HF10). A silane coating was then applied onto the treated ceramic surfaces, and they were adhesively cemented to the preparations. To perform the fatigue tests (staircase approach), a hemispheric stainless-steel piston (Ø = 40 mm) applied cyclic loads in the center of the crowns under water (initial load: 720 N; step-size: 70 N; cycles: 500,000; frequency: 20 Hz). Additionally, topographic, fractographic, and fractal analyses were carried out. The fatigue data were analyzed using the Dixon and Mood method.Results
Although the topographic and fractal analyses depicted the action of HF etching altering the superficial complexity and topography, the preponderant topography pattern was established by machining on CAD/CAM. All groups showed similar CLf (in N) (CTRL = 805.00 ± 91.23; HF3 = 781.25 ± 29.87; HF5 = 755.00 ± 154.49; HF10 = 833.75 ± 100.74).Significance
Etching with different HF acid concentrations did not promote a deleterious effect on the cyclic load-to-failure of machined lithium disilicate crowns. 相似文献9.
Magdalena Kirsten Ragai Edward Matta Renan Belli Ulrich Lohbauer Manfred Wichmann Anselm Petschelt José Zorzin 《Dental materials》2018,34(8):1102-1111
Objective
Low pH neutralization and subsequent remnant hydrophilicity can lead to hygroscopic expansion of self-adhesive resin cements (SARCs) after water storage. The aim of this in vitro study was to investigate the effects of hygroscopic expansion of SARCs, used as luting and partial core build-up material, on integrity and cement gap thickness increase of all-ceramic CAD/CAM crowns.Methods
Human third molars (n = 48) were prepared and anatomical all-ceramic CAD/CAM crowns were manufactured (VITABLOCS Mark II, VITA Zahnfabrik). Crowns internal surfaces were HF etched and silanized. The prepared teeth with their respective crowns were divided into 6 groups (n = 8). In groups 1, 3 and 5 the coronal dentin was removed to simulate a partial core build-up. Groups 1 and 2 were luted with iCEM (Heraeus Kulzer), 3 and 4 with RelyX Unicem 2 Automix (3M), 5 and 6 with Variolink Esthetic DC (Ivoclar Vivadent). All specimens were dual cured and stored in distilled water at 37 °C. Crown integrity was controlled at baseline and in regular intervals until 180 days. Cement gap thickness was measured using an optical 3D scanner (ATOS Triple scan, GOM) at baseline and after 180 days. Crown integrity was statistically analysed using Kaplan–Meier survival analysis and cement gap thickness increase using two-way ANOVA (α = 0.05).Results
After 180 days storage, crack formation was observed in all specimens of group 1 (mean survival time of 85.5 days), in one specimen of group 2 and in two specimens of group 4. Two-way ANOVA analysis revealed a statistically significant interaction between material type and build-up on cement gap size increase for iCEM.Significance
Within the limits of this study, the application of SARCs with low pH neutralization as partial build-up material under CAD/CAM crowns is not recommended for clinical use. 相似文献10.
Dong-Yeon Kim Ji-Hwan Kim Hae-Young Kim Woong-Chul Kim 《Journal of prosthodontic research》2018,62(1):56-64
Purpose
To evaluate the marginal and internal gaps of cobalt–chromium (Co–Cr) alloy copings fabricated using subtractive and additive manufacturing.Methods
A study model of an abutment tooth 46 was prepared by a 2-step silicone impression with dental stone. Fifteen stereolithography files for Co–Cr alloy copings were compiled using a model scanner and dental CAD software. Using the lost wax (LW), wax block (WB), soft metal block (SMB), microstereolithography (μ-SLA), and selected laser melting (SLM) techniques, 15 Co–Cr alloy copings were fabricated per group. The marginal and internal gaps of these Co–Cr alloy copings were measured using a digital microscope (160×), and the data obtained were analyzed using the non-parametric Kruskal–Wallis H-test and post-hoc Mann–Whitney U-test with Bonferroni correction.Results
The mean values of the marginal, axial wall, and occlusal gaps were 91.8, 83.4, and 163 μm in the LW group; 94.2, 77.5, and 122 μm in the WB group; 60.0, 79.4, and 90.8 μm in the SMB group; 154, 72.4, and 258 μm in the μ-SLA group; and 239, 73.6, and 384 μm in the SLM group, respectively. The differences in the marginal and occlusal gaps between the 5 groups were statistically significant (P < .05).Conclusions
The marginal gaps of the LW, WB, and SMB groups were within the clinically acceptable limit, but further improvements in the μ-SLA and SLM approaches may be required prior to clinical implementation. 相似文献11.
Ehsan Homaei Xiao-Zhuang Jin Edmond Ho Nang Pow Jukka Pekka Matinlinna James Kit-Hon Tsoi Khalil Farhangdoost 《Dental materials》2018,34(7):e149-e157
Objectives
The purpose of this study was to estimate the fatigue life of premolars restored with two dental ceramics, lithium disilicate (LD) and polymer infiltrated ceramic (PIC) using the numerical method and compare it with the published in vitro data.Methods
A premolar restored with full-coverage crown was digitized. The volumetric shape of tooth tissues and crowns were created in Mimics®. They were transferred to IA-FEMesh for mesh generation and the model was analyzed with Abaqus. By combining the stress distribution results with fatigue stress–life (S–N) approach, the lifetime of restored premolars was predicted.Results
The predicted lifetime was 1,231,318 cycles for LD with fatigue load of 1400 N, while the one for PIC was 475,063 cycles with the load of 870 N. The peak value of maximum principal stress occurred at the contact area (LD: 172 MPa and PIC: 96 MPa) and central fossa (LD: 100 MPa and PIC: 64 MPa) for both ceramics which were the most seen failure areas in the experiment. In the adhesive layer, the maximum shear stress was observed at the shoulder area (LD: 53.6 MPa and PIC: 29 MPa).Significance
The fatigue life and failure modes of all-ceramic crown determined by the numerical method seem to correlate well with the previous experimental study. 相似文献12.
Deyar Jallal Hadi Mahmood Michael Braian Christel Larsson Ann Wennerberg 《Dental materials》2019,35(3):486-494
Objectives
To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive.Methods
Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student’s t-test.Results
There were significant differences in mean values for accuracy/production tolerance among different manufacturing techniques for both production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p ≤ .001) and conventional wax copings (p ≤ .001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p ≤ .001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p ≤ .001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p ≤ .001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025).Significance
The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique. 相似文献13.
Michael Wendler Renan Belli Anselm Petschelt Daniel Mevec Walter Harrer Tanja Lube Robert Danzer Ulrich Lohbauer 《Dental materials》2017,33(1):99-109
Objective
Strength is one of the preferred parameters used in dentistry for determining clinical indication of dental restoratives. However, small dimensions of CAD/CAM blocks limit reliable measurements with standardized uniaxial bending tests. The objective of this study was to introduce the ball-on-three-ball (B3B) biaxial strength test for dental for small CAD/CAM block in the context of the size effect on strength predicted by the Weibull theory.Methods
Eight representative chairside CAD/CAM materials ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Specimens were prepared with highly polished surfaces in rectangular plate (12 × 12 × 1.2 mm3) or round disc (Ø = 12 mm, thickness = 1.2 mm) geometries. Specimens were tested using the B3B assembly and the biaxial strength was determined using calculations derived from finite element analyses of the respective stress fields. Size effects on strength were determined based on results from 4-point-bending specimens.Results
A good agreement was found between the biaxial strength results for the different geometries (plates vs. discs) using the B3B test. Strength values ranged from 110.9 MPa (Vitablocs Mark II) to 1303.21 MPa (e.max ZirCAD). The strength dependency on specimen size was demonstrated through the calculated effective volume/surface.Significance
The B3B test has shown to be a reliable and simple method for determining the biaxial strength restorative materials supplied as small CAD/CAM blocks. A flexible solution was made available for the B3B test in the rectangular plate geometry. 相似文献14.
Objective
The aim of this laboratory study was to analyze the influence of titanium dioxide (TiO2) content and antagonistic material on the wear of polyetherketoneketones (PEKKs).Methods
Twenty-four disk-shaped specimens of two PEKK materials containing either 10 wt% or 20 wt% TiO2 particles (P10 and P20) were dynamically loaded in a chewing simulator with 49 N and additional thermal cycling (5–55 °C). Subgroups of 8 specimens each were loaded with spherical antagonists made from either steatite ceramic (St), zirconia (Zr), or the same PEKK material (P10 or P20). After 120,000, 240,000, 480,000, 840,000, and 1,200,000 loading cycles the vertical substance loss and the volume loss of the loaded specimens were evaluated using a laser scanner. Data were checked considering the normal distribution (Shapiro–Wilk test) and were inspected for significant differences by means of single factor variance analyses and post hoc pair comparison (Games-Howell test).Results
After 1,200,000 chewing cycles, statistical analyses revealed a significant influence of the antagonistic material. A significant difference was also found between the tested PEKKs if Zr was used as the antagonist. The volume loss ranged from between 0.073 mm3 (P20-P20) and 0.228 mm3 (P10-St), and the vertical substance loss ranged between 73.71 μm (P20-P20) and 115.268 μm (P10-Zr).Significance
The inclusion of TiO2 particles influences the wear behavior of PEKK materials. 相似文献15.
A. Arena P. Baldissara L. Ciocca R. Scotti C. Monaco 《Journal of prosthodontic research》2019,63(1):100-104
Purpose
To evaluate the influence of the preparation design and spacing parameters on the risk of chipping of crowns made by CEREC Bluecam before cementation.Methods
A knife-edge preparation and a chamfer preparation were made on upper premolars. The teeth were scanned and two Co–Cr alloy replicas were made. Fifteen full crowns were manufactured for four groups using CEREC. The groups differed in type of preparation (knife-edge (KE) or chamfer (CHA)) and spacing parameters: spacer (0 or 150 μm), marginal adhesive gap (10 or 50 or 150 μm) and margin thickness (0 or 300 μm). The four groups were: CHA 150 (spacer)- 50 (marginal adhesive gap)- 0 (margin thickness), KE 150-50-0, KE 150-50-300 and KE 150-150-300. The crowns were loaded before cementation by using an Instron machine to simulate the masticatory load applied during a trial. Differences in means were compared using two-way ANOVA and a post-hoc test (Tukey Test). The level of significance was set at P = 0.05.Results
The fracture values, ordered from least to most resistant, were: KE 150-50-300 group, CHA 150-50-0 group, KE 150-50-0 group and KE 150-150-300 group. Two-way ANOVA revealed statistically significant differences between pairs of means (p < 0.05). Tukey’s test showed that restorations of the KE 150-150-300 group can withstand a load significantly higher than that of other groups (p < 0.01). In this group, the failures were mostly minor chippings, while the other groups had mostly major chippings and fractures.Conclusions
Marginal adhesive gap can affect the trial of a full crown. 相似文献16.
Abdulrahman Elmougy Alvaro Muñoz Schiemann Duncan Wood Sarah Pollington Nicolas Martin 《Dental materials》2018,34(10):1509-1517
Objectives
To characterise the mechanical properties of the machinable polymers Pekkton® (Cendres-Meteaux, Biel/Bienne, Switzerland), Lava Ultimate® (3MESPE, Seefeld, Germany), Vita Enamic® (Ivoclar Vivadent, Schaan, Liechtenstein) and the ceramic IPS e.Max Press® (Ivoclar Vivadent, Schaan, Liechtenstein). To determine the structural integrity of full coverage crowns fabricated from these materials.Methods
The following tests were conducted: Biaxial flexural strength (BFS) using the piston on 3 balls jig (n = 10); Vickers Hardness (VH) 10 indentations per sample with 10 kg load & 20 s dwell time (n = 5); Hygroscopic Expansion Change (HEC) in artificial saliva over 68 days (n = 5). Structural Strength (SS) of teeth analogues (n = 20) restored with monolithic crowns from the four materials. Mean values and standard deviations for BFS, VH, HEC and SS tests were calculated and compared using one-way ANOVA with post-hoc Tukey’s test at a level of 5% significance.Results
BFS: IPS e.Max Press® (317 MPa ± 37 MPa), Pekkton® (227 MPa ± 18 MPa), Lava Ultimate® (145 MPa ± 18 MPa) and Vita Enamic® (137 MPa ± 7 MPa) with a significance between groups of p < 0.0001. VH: IPS e.Max Press® (5064 MPa ± 131 MPa), Vita Enamic® (1976 MPa ± 12 MPa), Lava Ultimate® (924 MPa ± 27 MPa) and Pekkton® (445MPa ± 21 MPa) with a significance between groups of p < 0.0001. HEC (%vol change): Pekkton® (0.14% ± 0.14%), Vita Enamic® (0.38% ± 0.16%) and Lava Ultimate® (1.06% ± 0.17%). SS for full-coverage crowns: Pekkton® (2037 N ± 49 N no fracture), IPS e.Max Press® (1497 N ± 165 N), Lava Ultimate® (1476 N ± 142 N) and Vita Enamic® (1127 N ± 108 N).Significance
The properties investigated suggest that full coverage monolithic PEKK crowns possess adequate mechanical and physical properties for use in the posterior region of the mouth. These results must be considered alongside other data including clinical studies. 相似文献17.
Objectives
Dental materials that can form apatite offer the potential to not only prevent demineralisation but enhance remineralisation of the enamel. The objective of this study was to investigate the ability of a novel BAG-resin adhesive to form apatite in 3 immersion media.Methods
A novel fluoride containing BAG-resin adhesive described previously, with 80% by weight filler load, was used to fabricate 90 disks. Each disk was immersed in 10 ml of either tris buffer (TB), or artificial saliva at pH = 7 (AS7) or pH = 4 (AS4). At ten time points (from 6 h to 6 months), three disks were taken from each of the solutions and investigated by ATR-FTIR, XRD and SEM.Results
The BAG-resin formed apatite on the disk surface, which increased with time, especially in AS4 and AS7. The apatite crystals formed in AS7 were highly oreintated and the oreintation increased with time.Significance
This novel BAG-resin adhesive differs from the currently used adhesives by promting apatite formation, particularly under acidic conditions. Thus, applied in the clinical situation to bond orthodontic brackets, it may discourage the frequent occurrence of white spot lesion formation around the brackets. 相似文献18.
Mareike Warkentin Cora Freyse Olaf Specht Detlef Behrend Reinhard Maletz Ralf Janda Peter Ottl 《Dental materials》2018,34(7):1036-1040
Objective
To investigate if Vickers microhardness of dentin and enamel correlated with acoustic velocity c(l) or acoustic reflection from the sample’s top (amplitude).Methods
Eight transversal sections of a sound human tooth were investigated with scanning acoustic microscopy (SAM) and Vickers microhardness measurements. Longitudinal acoustic velocity c(l), amplitude and microhardness MHV were evaluated and for each c(l) test point corresponding amplitude and MHV were linearly interpolated and graphically analyzed. Spearman rank order correlation (rS) was calculated (p < 0.05).Results
c(l) was predominantly 6100–7000 ms?1 in enamel and 3800–4600 ms?1 in dentin and correlated significantly with MHV with 27–420 in enamel and 20–90 in dentin (rs = 0,57). Amplitudes significantly correlated with MHV, too, but even better (rs = 0,77).Significance
Acoustic velocity and amplitudes were appropriate to detect microhardness differences of dentin and enamel and certain value ranges of both could be assigned to certain MHV ranges. Further research is needed to differentiate more precisely between the different hard tooth tissues. 相似文献19.
Lippo Lassila Filip Keulemans Eija Säilynoja Pekka K. Vallittu Sufyan Garoushi 《Dental materials》2018,34(4):598-606
Objective
The aim was to evaluate the effect of short glass-fiber/filler particles proportion on fracture toughness (FT) and flexural strength (FS) of an experimental flowable fiber-reinforced composite (Exp-SFRC) with two methacrylate resin formulations. In addition, we wanted to investigate how the fracture-behavior of composite restorations affected by FT values of SFRC-substructure.Methods
Exp-SFRC was prepared by mixing 50 wt% of dimethacrylate based resin matrix (bisGMA or UDMA based) to 50 wt% of various weight fractions of glass-fiber/particulate filler (0:50, 10:40, 20:30, 30:20, 40:10, 50:0 wt%, respectively). FT and FS were determined for each experimental material following standards. Specimens (n = 8) were dry stored (37 °C for 2 days) before they were tested. Four groups of posterior composite crowns (n = 6) composed of different Exp-SFRCs as substructure and surface layer of commercial particulate filler composite were fabricated. Crowns were statically loaded until fracture. Failure modes were visually examined. The results were statistically analysed using ANOVA followed by post hoc Tukey’s test.Results
ANOVA revealed that ratio of glass-fiber/particulate filler had significant effect (p < 0.05) on tested mechanical properties of the Exp-SFRC with both monomer systems. Exp-SFRC (50 wt%) had significantly higher FT (2.6 MPam1/2) and FS (175.5 MPa) (p < 0.05) compared to non-reinforced material (1.3 MPam1/2, 123 MPa). Failure mode analysis of crown restorations revealed that FT value of the substructure directly influenced the failure mode.Significance
This study shows that short glass-fibers can significantly reinforce flowable composite resin and the FT value of SFRC-substructure has prior importance, as it influences the crack arresting mechanism. 相似文献20.
Marianne Salas Cristina Lucena Luis Javier Herrera Ana Yebra Alvaro Della Bona María M. Pérez 《Dental materials》2018,34(8):1168-1174