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An investigation of the mechanical properties of a new ceramo-metal restoration (Captek)
No full textPLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please log in with a valid BU account to access and click Download. If you are the author of this work and would like to make it publicly available, please contact [email protected] (D.Sc.D.)--Boston University. Henry M. Goldman School of Graduate Dentistry, 1995.Includes bibliographical references (leaves 295-315)The Captek metal-ceramic system is based upon the formation of an interpenetrating Au-Au/Pt/Pd network. The technique consists of sintering Au/Pt/Pd onto the refractory die to form a porous network which is then infused with molten Au. This study compares the marginal accuracy of Captek crowns and three unit bridges with conventional metal-ceramic restorations; the maximum compressive load that the Captek crowns and three unit bridges (with and without porcelain bonding agent) can sustain in comparison to corresponding conventional metal ceramic crowns and bridges, and the ceramo-metal bond strength.
A maxillary central incisor crown preparation was produced on an ivorine tooth with a circumferential chamfer margin of 1.2 mm on the labial, 0.8mm on the lingual and blend type at the proximal. Thirty identical replicas of the master dies were cast in metal upon which the crowns were fabricated. A master model for the three unit bridge with premolar and molar abutment and pontic space was fabricated. Identically contoured porcelain fused to metal crowns and bridges were fabricated according to the manufacturer's instruction into three groups: Group A.) Conventional porcelain fused to high noble metal-ceramic alloy, Group B.) Captek with porcelain bonding agent, Group C.) Captek without porcelain bonding agent. The crown and bridge contours were standardized using jigs. Marginal opening was measured at fourteen locations on both bridge abutments and at eight locations on the crowns at 100X using a traveling microscope. The mean marginal gap of the crowns (UM) is: Group A.) 17.13[plus or minus]3.34, Group B.) 14.7[plus or minus]2.91, Group C.) 14.41[plus or minus]3.06. The mean marginal gap of the bridges (UM) are: Group A.) 21.38[plus or minus]3.60, Group B.) 17.64[plus or minus]3.54, Group C.) 17.62[plus or minus]3.82. ANOVA and Newman-Keuls test revealed a statistically significant difference in marginal fit at p[less than]0.05 in both crown and bridge groups.
All crowns were cemented to their respective dies as well as bridges were cemented to bridge supporting models with zinc phosphate cement and positioned in an Instron so that a compressive load was applied at a cross head speed of 0.5 mm/min. The loading force at the initial crack and at catastrophic failure were recorded for bridges and at failure for crowns. The mean load bearing capacity at initial crack and at failure for bridges (kg) is: Group A.) 192.71[plus or minus]17.24 and 213.49[plus or minus]29.43, Group B.) 191.75[plus or minus]15.4 and 210.28[plus or minus]22.01, Group C.) 193.58[plus or minus]8.27 and 216.97[plus or minus]13.10. The mean fracture load (kg) for crowns is: Group A.) 74.20[plus or minus]14.54, Group B.) 74.75[plus or minus]15.92, Group C.) 74.38[plus or minus]8.93. ANOVA and Newman-Keuls test revealed no statistically significant difference in load bearing capacity at p[less than]0.05 between experimental group in each category of restoration. [TRUNCATED
The determination of the effect of the internal surface roughness and cement space upon crown retention
No full textPLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please log in with a valid BU account to access and click Download. If you are the author of this work and would like to make it publicly available, please contact [email protected] (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1990 (Prosthodontics).Bibliography : leaves 89-105.This study evaluated crown retention relative to five variables; core materials (amalgam and composite resin core), cements (zinc phosphate, glass ionomer and resin cement), cement film thicknesses (50, 100, and 150 microns), internal surface roughness of retainers, and thermal stress.
Three hundred sixty (360) cylindrical amalgam cores (Valiant, Caulk, Dentsply) and composite resin cores (Core-Paste, Den Mat) were made in a teflon coated aluminum mold. Sixty cores of each type were 8.7, 8.8, 8.9 mm. in diameter and 6.0 mm. in length. Three hundred sixty (360) cylindrical retainers 12.0 mm. in external diameter, 9.0 mm. in internal diameter, 1.5 mm. thickness, and 6.0 mm. in length were made from base metal alloy (Rexillium III, Rx. Jenerix, Wallingford, CT.). One hundred eighty (180) cylindrical retainers were sandblasted with fine (60 microns) aluminum oxide abrasive, and one hundred eighty (180) were sandblasted with coarse (280 microns) aluminum oxide abrasive. All cores were cemented to cylindrical retainers using three types of cement; zinc phosphate cement (Mission, White Dental Inc., NJ, USA), glass ionomer cement (Ketac-Cem, Espe, Premier, PA, USA), and resin cement (Panavia Ex., Kuraray, Japan). Thirty six (36) groups of core-retainer assemblies, consisting of ten (10) samples for each group were obtained according to cement type, cement film thickness, core material, and internal surface roughness of retainers. Each group was subdivided into 2 groups yeilding a total of seventy two (72) subgroups, consisting of thirty six (36) control groups and thirty six (36) experimental groups of five (5) samples each. All samples were stored in 100 % humidity at 37 C Samples in experimental groups were thermocycled one week after cementation. All samples were tested for retentive bond strength by pushing cores from their retainers at a constant rate (0.02 cm/min) with the Instron universal testing machine (Instron Corp., Canton, MA). The values obtained were subjected to a five way analysis of variance (ANOVA). Further statistical analysis of variance was pursued by using the Newman-Keuls test.
The highest bond strength was obtained with composite resin cores (Core-Paste) cemented with resin cement (Panavia Ex.) to retainers with coarse internal surfaces at a cement film thickness of 50 microns. The lowest bond strength was obtained with composite resin cores (Core-Paste) cemented with glass ionomer cement (Ketac-Cem) to retainers with fine internal surfaces at a cement film thickness of 150 microns. Amalgam (Valiant) was superior to the other core materials no matter what type of cement used. Resin cores appear to contribute a lower bond strength than amalgam except when used with resin cement (Panavia Ex.) Zinc phosphate (Mission, White Dental Inc.) and resin cement (Panavia Ex.) appeared to be far better than glass ionomer cement (Ketac-Cem, Espe, Premier) for all samples. Thermocycling reduced the bond strength of all cement-core samples. Cement film thicknesses of 50 and 100 microns proved to be acceptable. Retainers with coarse internal surfaces exhibited a higher bond strength than those with fine internal surfaces
Effect of different sintering process on flexural strength of translucency monolithic zirconia
Get PDFSintering process is responsible for the strength of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on flexural strength of translucency monolithic zirconia. One hundred and thirty five zirconia bar specimens (width-length-thickness = 10×20×1.5 mm) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic and randomly divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintered-holding times [shortening- (HS, 60 min), regular- (HR, 120 min), and prolonged- (HP, 180 min) sintered-holding time]. Flexural strength was determined using three-point bending test in a universal testing machine at 1 mm/min crosshead speed. An analysis of variance (ANOVA) and Tukey?s multiple comparisons were used to determine for statistically significant difference of flexural strength (?=0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristics strength (?o) of the flexural strength. The crystal sizes were microscopically examined using scanning electron microscope (SEM). The phase composition of zirconia was determined using X-ray diffraction (XRD). The mean±sd (MPa), m, and ?o of flexural strength were 1080.25±217.19, 5.54, and 1167.53 for SDHS, 1243.41±233.17, 5.19, and 1352.30 for SDHR, 1298.92±235.68, 6.24, and 1394.79 for SDHP, 1303.34±171.87, 8.40, and 1377.90 for SRHS, 1331.73±278.84, 5.31, and 1444.50 for SRHR, 1348.13±283.35, 5.32, and 1460.68 for SRHP, 1458.45±289.19, 4.51, and 1604.41 for SIHS 1581.34±190.56, 8.20, and 1675.21 for SIHR and, 1604.10±139.52, 12.57, and 1667.90 for SIHP. The flexural strength was significantly affected by altering sintering temperatures and holding times (p<0.05). Enlarging grain size and increasing t?m phase shifting related with raising temperatures and times. Increasing sintering temperature and prolonged sintered-holding time lead to enhancing flexural strength of translucency monolithic zirconia, and are suggested for sintering process to achieve durable restoration
Influence of thermal tempering processes on color characteristics of different monolithic computer-assisted design and computer-assisted manufacturing ceramic materials
Get PDFThe optical properties of dental restoration were influenced by the sintering parameters. This study investigated the effects of different tempering processes on optical properties of three monolithic Cad-Cam ceramics. 135 monolithic material bars (4 mm width, 14 mm length, 1.2 mm thickness) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (inCoris TZI, I), zirconia-reinforced lithium silicate (Vita Suprinity, V), and lithium disilicate glass (e.max CAD, E) ceramics, with different tempering processes through slow (S), normal (N), and fast (F) cooling (n=15). The color appearance (?EW), translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) were determined. ANOVA and Bonferroni?s multiple comparisons were determined for significant difference (?=0.05). The grain sizes were microscopically examined by scanning electron microscope. The phase transformation of zirconia was determined using X ray diffraction. The mean±sd of ?EW, TP, CR, OP were 74.15±0.46, 1.26±0.15, 0.977±0.006, 1.02±0.12 for IS; 74.00±0.83, 1.27±0.19, 0.977±0.007, 1.02±0.12 for IN; 74.44±0.64, 1.70±0.08, 0.965±0.003, 1.30±0.07 for IF; 73.35±1.32, 2.44±0.24, 0.958±0.006, 2.10±0.20 for VS; 66.37±0.88, 4.05±0.3, 0.911±0.010, 3.18±0.20 for VN; 67.02±0.65, 3.79±0.17, 0.919±0.006, 3.01±0.13 for VF; 60.01±0.30, 5.53±0.17, 0.821±0.006, 2.71±0.06 for ES; 60.18±0.23, 5.49±0.17, 0.822±0.006, 2.66±0.05 for EN; and 59.82±0.26, 5.36±0.06, 0.826±0.002, 2.64±0.07 for EF. The color parameters were significantly affected by type of materials, tempering processes, and their interactions (p<0.05). Phase transformation from t?m related with tempering procedure for zirconia. Rapid thermal tempering process of Y-TZP resulted in larger grain size and t?m phase transformation leading to higher translucency. To achieve optimum translucency, a fast thermal tempering process was suggested for inCoris TZI and IPS e.max CAD, whilst a normal tempering process was recommended for Vita Suprinity
Influence of different veneering techniques and thermal tempering on flexural strength of ceramic veneered yttria partially stabilized tetragonal zirconia polycrystalline restoration
Get PDFDifferent technique for ceramic veneering and thermal tempering process are expected to be a reason for alteration in strength of ceramic veneered zirconia. This study evaluates the effect of different veneering technique and varied thermal tempering process on flexural strength of ceramic veneered zirconia. Ceramic veneered zirconia bars (25 mm length, 4 mm width, 0.7&1.0mm of zirconia & ceramic thickness) were prepared from zirconia block (e.max® ZirCAD), sintered at 1500°C for 4 hours, and veneered with ceramics with different techniques including CAD-fused using e.max CAD® (C), Pressed-on using e.max® Zirpress (P), and layering using e.max® ceram (L), with different tempering process through fast (F), medium (M), and slow (L) cooling (n=15). The specimens were determined for flexural strength on a universal testing machine. ANOVA and Bonferroni?s multiple comparisons were used to determine for significant difference (?=0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristics strength (?c). The interfaces were microscopically examined. The phase transformation of zirconia was determined using X ray diffraction. The mean±sd (MPa), m, ?c of flexural strength were 922.06±83.45, 12.78, 958.32 for CF, 924.26±74.64, 14.28, 959.62 for CM, 930.25±92.42, 11.83, 970.83 for CS, 518.29±59.97, 10.11, 542.97 for PF, 516.50±67.51, 8.75, 539.17 for PM, and 520.51±42.38, 14.59, 544.51 for PS, 604.36±64.09, 11.28, 630.67 for LF, 583.81±56.95, 11.67, 609.81 for LM, 547.33±52.23, 12.19, 569.36 for LS. The flexural strength was significantly affected by veneering technique (p0.05). Phase transformation from t?m related with veneering and tempering procedure. Strength of ceramic veneered zirconia associated with different veneering techniques, but not directly related with tempering process. CAD-on ceramic veneering zirconia is benefit for enhancing the strength of ceramic bilayer and was recommended as a method for ceramic veneering zirconia
Effect of sintering process on color parameters of nano-sized yttria partially stabilized tetragonal monolithic zirconia
Get PDFSintering process is responsible for aesthetic of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on color parameters of monolithic zirconia. One hundred and thirty five zirconia bar specimens (width-length-thickness = 10×20×1.5 mm) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic and randomly divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintered-holding times [shortening- (HS, 60 min), regular- (HR, 120 min), and prolonged- (HP, 180 min) sintered-holding time]. Color appearance (?E), translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) were determined with spectrophotometer. An analysis of variance (ANOVA) and Tukey?s multiple comparisons were used to determine for statistically significant difference of color parameters (?=0.05). Crystal sizes were microscopically examined using scanning electron microscope (SEM), and phase composition of zirconia was determined using X-ray diffraction (XRD). The mean±sd for ?E, TP, CR, OP were 82.28±1.27, 1.4±0.13, 0.982±0.004, 1.25±0.15 for SDHS, 78.38±0.74, 2.16±0.10, 0.967±0.005, 1.90±0.11 for SDHR, 74.43±0.91, 2.24±0.10, 0.964±0.004, 1.94±0.09 for SDHP, 76.31±1.22, 3.03±0.10, 0.945±0.003, 2,50±0.09 for SRHS, 74.51±1.27, 3.19±0.17, 0.942±0.003, 2.65±0.16 for SRHR, 73.94±0.49, 3.42±0.10, 0.937±0.003, 2,83±0.09 for SRHP, 76.30±0.43, 3.16±0.09, 0.937±0.002, 2.48±0.09 for SIHS 76.73±1.15, 3.05±0.20, 0.939±0.005, 2.38±0.17 for SIHR, and 75.32±1.37, 2.95±0.18, 0.942±0.006, 2.33±0.15 for SIHP. The ?E, TP, CR, and OP were significantly affected by altering sintering temperatures and holding times (p<0.05). Increasing sintering temperature and extending sintering time significantly improved color appearance, translucency, contrast, and opalescence of Y-TZP (p<0.05) as evidenced by enlarging grain size and increasing t?m phase shift. Raising sintering temperature and prolonging sintering time lead to better color appearance, translucency, contrast and opalescence of nano-sized monolithic Y-TZP, and are suggested for sintering process
Effect of glass infiltration and modified cooling rates on color characteristics alteration of monochrome and multilayer high yttrium oxide containing zirconia
No full textSintering technique impacted color of zirconia. This study examined the effect of glass infiltration and altering cooling rate on color alteration of monochrome (Mo) and multilayer (Mu) 5 mol% yttria-partially stabilized zirconia (5Y-PSZ). 180 specimen
Flexural Strength Of Provisional Restorative Materials Upon Aging
Get PDFBackground: Aging may affect strength of provisional restorative materials.Objective: This study evaluated the effect of aging on strength of heat-polymerized polymethyl methacrylate (Hp-PMMA), auto-polymerized (Ap) PMMA, bis-phenyl-glycidyl dimethacrylate (Bis-GMA), and computer-aided design/computer-aided manufacturing (CAD/CAM) containing either PMMA or acrylate resin.Methods: Two hundred-ten bars (2x2x25mm) were fabricated from Hp-PMMA: Major C&B (M); Ap-PMMA: Unifast™ (U); Bis-acryl: Protemp™ (P), Luxatemp® (L); PMMA-CAD/CAM: Telio® CAD (T), artBloc® (R); and acrylate-CAD/CAM: Vita CAD Temp® (V). Each was divided into aging- (A) and non-aging- (N) groups (n=15 each). A-groups were thermo-cycled (5°C v.s 55°C, 30 sec each, 5000 cycles). Flexural strength was determined in universal testing machine at 1 mm/min crosshead speed, 50N/min loading. An analysis of variance (ANOVA) and Bonferroni’s test was determined for significant difference (α=0.05). Weibull statistics were determined for Weibull modulus (m), and characteristics strength (σo). Scanning electron micrographs (SEM) were examined for fracture surfaces.Results: The values (means±sd (MPa), m, σo) were (84.62± 3.73, 25.23, 86.53) and (84.05± 6.39, 13.21, 87.28) for VN and VA, (133.49± 4.32, 34.09, 135.54) and (123.11± 4.55, 28.76, 125.35) for TN and TA, (120.59± 6.94, 19.01, 123.84) and (119.96± 6.90, 19.21, 123.16) for RN and RA, (94.35± 4.07, 25.82, 96.24) and (93.07± 3.22, 32.19, 94.58) for PN and PA, (110.60± 6.20, 19.99, 113.44) and (97.23± 7.77, 13.82, 100.78) for LN and LA, (114.30± 5.21, 23.90, 116.79) and (112.21± 5.70, 19.86, 115.13) for MN and MA, and (89.45± 2.96, 32.77, 90.88) and (84.96± 5.33, 17.66, 87.42) for UN and UA respectively. T revealed the highest, whereas V possessed the lowest strength for both N- and A- condition. Aging significantly affected strength.Conclusions: Flexural strengths were differences among materials. PMMA-CAD/CAM possessed the highest, while acrylate-CAD/CAM possessed the lowest. Hp-PMMA showed better strength than Ap-PMMA. Bis-acryl resin was stronger than Ap-PMMA. Aging reduced strength for all materials tested
Fracture toughness of different monolithic zirconia upon post-sintering processes
Get PDFSurface treatments are expected to be a reason for alteration in fracture resistance of zirconia. This study evaluated the effect of post-sintering processes on the fracture toughness of different types of monolithic zirconia. Material an
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