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ABSTRACT: Veneering ceramic materials designed to be used with high noble alloy and zirconia-based restorations have been reported to be susceptible to chipping in vivo.
The purpose of this study was to evaluate and compare the fracture toughness of heat-pressed and layered ceramics intended for zirconia and high-noble alloy substrates.
Bar specimens were fabricated from 8 different ceramics (Ivoclar-Vivadent [I] and Noritake [N]) intended for pressing (P) and layering (L) to high noble alloy (M) and zirconia (Z) substrates, following the ISO 6872 protocol. The single edge notch beam test method was used to create a notch in the center of each specimen, which was then tested with a universal testing machine (n=6, cross-head speed=0.5 mm/min) and the fracture force values recorded. These values were used to calculate the fracture toughness (K1c) for each specimen. Fracture surfaces were examined with a scanning electron microscope, and the basic components of the tested ceramics were determined by using energy dispersive x-ray (EDX) spectroscopy. Data were analyzed with 3-way ANOVA, followed by multiple comparisons using the Holm method (α=.05).
The mean (SD) of the calculated fracture toughness values obtained ranged from 1.20 (0.04) MPa·m(1/2) (group NZL) to 1.74 (0.04) MPa·m(1/2) (group IZL). Fracture toughness was significantly higher in group IZL (1.74) than group IZP (1.41), but lower in group NZL (1.20) than group NZP (1.36) (P<.001). Fracture toughness was somewhat lower in group IML (1.36) than group IMP (1.47) (P=.018), and no significant difference was found between group NML and group NMP (P=.14). Veneering ceramics used with a metal substrate showed a crystalline structure mixed with a glassy phase pattern on the fracture surface. The results of EDX analysis on the fracture surfaces indicated that the tested ceramics were composed of Si, Al, K, Na, Mg, and oxygen elements.
Ceramics used for veneering zirconia substrate may have various fracture toughness values that relate primarily to the processing technique.
The Journal of prosthetic dentistry 04/2013; 109(4):234-40. · 1.22 Impact Factor
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ABSTRACT: Although various zirconia abutments have been introduced, insufficient data exist regarding the maximum load capacity of internal tri-channel connection zirconia implant abutments with various implant-abutment interfaces.
The purpose of this in vitro study was to compare the maximum load capacity of 3 different types of internal tri-channel connection zirconia abutments and to assess their mode of failure.
The study investigated 3 groups (n=20) of zirconia implant abutments with different implant-abutment interfaces. Group AllZr consisted entirely of zirconia (Aadva CAD/CAM Zirconia Abutment), group FrZr of a titanium insert friction-fitted to the zirconia abutment component (NobelProcera Abutment Zirconia), and group BondZr of a titanium insert bonded to the zirconia abutment component (Lava Zirconia abutment). All the abutments were thermal cycled for 20 000 cycles between 5°C and 55°C. Sixty test implants made of titanium (Dummy NobelReplace) were embedded in autopolymerizing acrylic resin, and 60 zirconia copings (Lava Zirconia) with a uniform thickness of 2.0 mm were fabricated and bonded to the abutments. A universal testing machine was used to statically load all the specimens at a crosshead speed of 1 mm/min. The maximum load was recorded and used as the failure load. The fractured specimens were collected and representative specimens were studied with a stereomicroscope and scanning electron microscope (SEM). One-way ANOVA and post hoc comparisons with the Tukey HSD tests were used for statistical analysis (α=.05).
The mean (SD) maximum load capacity was 484.6 (56.6) N for NobelProcera, 503.9 (46.3) N for Aadva, and 729.2 (35.9) N for Lava abutments. The maximum load capacity of Lava abutments was significantly higher than that of Aadva or NobelProcera (P< 05). No significant difference between Aadva and NobelProcera abutments was noted. The mode of failure among the Aadva, NobelProcera, and Lava abutments was different.
With standard diameter internal tri-channel connection implants, the maximum load capacity of the Lava abutment was significantly higher than that of the Aadva or NobelProcera abutment. No significant difference in maximum load capacity was noted between Aadva and NobelProcera abutments. However, the fracture behavior of all 3 abutments was different.
The Journal of prosthetic dentistry 04/2013; 109(4):255-63. · 1.22 Impact Factor
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ABSTRACT: In recent years, zirconium dioxide-based partial fixed dental prostheses (FDP) have been suggested as an alternative treatment to traditional metal ceramic FDPs. However, clinical studies evaluating their longevity and related complications are limited.
The purpose of this cohort clinical study was to assess the efficacy of zirconium dioxide-based posterior 3-unit FDPs.
Twenty 3-unit posterior FDPs (Lava) were placed in 16 participants missing a second premolar or a first molar. All participants met specific inclusion and exclusion criteria and provided informed consent. All teeth were prepared in a standardized manner: occlusal reduction of 1.5 to 2 mm; axial reduction of 1 to 1.5 mm; a 1.0 mm 360-degree rounded shoulder placed 0.5 mm subgingivally on the facial aspect and supragingivally on the lingual aspect on sound tooth structure; and rounded internal line angles. Definitive impressions were made with vinyl polysiloxane impression material. Frameworks were fabricated by using computer-aided design and computer-aided manufacturing (CAD/CAM) technology with a uniform retainer thickness of 0.6 mm and a minimal connector surface area of 9 mm(2). Restorations were luted with resin-modified glass ionomer cement (Rely-X Luting). Participants were recalled at 2 weeks, 6 months, and 12 months, and thereafter, annually for up to 60 months. Clinical fracture measurements, marginal discoloration, marginal adaptation, radiographic proximal recurrent caries, and periapical pathoses were assessed over time by using modified Ryge criteria. The probability distributions of these variables were calculated for the baseline data and for the recall data. An analysis of survival was made by using the Kaplan-Meier method.
Eighteen FDPs were clinically evaluated at 5 years and 1 at 48 months. Fifteen were rated Alpha for fracture measurements, and 2 were rated Bravo (minor chipping of veneering porcelain and not requiring restoration replacement). Two were rated Charlie (major chipping of veneering porcelain and requiring restoration replacement). Eighteen FDPs were rated Alpha for marginal integrity, and 1 rated Bravo. All restorations were rated Alpha for marginal discoloration. One participant experienced root fracture after 60 months, while another was treated surgically for a periapical pathosis on an endodontically treated abutment.
Zirconium dioxide-based posterior 3-unit FDPs performed well after 5 years of service.
The Journal of prosthetic dentistry 10/2012; 108(4):214-22. · 1.22 Impact Factor
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ABSTRACT: Concerns have been expressed about the effect of aging on the mechanical properties of zirconia.
The purpose of this study was to assess the accelerated aging characteristics of 3 commercially available yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) materials by exposing specimens to hydrothermal treatments at 134°C, 0.2 MPa and 180°C, 1.0 MPa in steam.
Thin bars of Y-TZP from 3 manufacturers, Lava, Zirkonzahn, and Zirprime, n=30 for each brand (22 × 3 × 0.2 mm), were cut and ground from blocks and sintered according to the manufacturer's specifications. Control specimens (n=10) for each brand were evaluated in the as-received condition. Experimental specimens were artificially aged at standard autoclave sterilization conditions,134°C at 0.2 MPa (n=5 per group at 50, 100, 150, and 200 hours) and standard industrial ceramic aging conditions, 180°C at 1.0 MPa (n=5 per group at 8, 16, 24, 28, and 48 hours). Tetragonal to monoclinic transformation was measured by using X-ray diffraction (XRD) for all groups. Flexural strength was measured in 4-point bending (ASTM1161-B) for all groups. Fracture surfaces were examined by scanning electron microscopy (SEM). Data were analyzed as a function of aging time. The statistical comparisons were based on the log value and 2-way ANOVA with heteroscedasticity-consistent standard errors used to compare mean strength among conditions (α=.05).
After 200 hours at 134°C and 0.2 MPa, flexural strength (SD) decreased significantly from 1156 (87.6) MPa to 829.5 (71) MPa for Lava; 1406 (243) MPa to 882.7 (91) MPa for Zirkonzahn; and 1126 (92.4) MPa to 976 (36.4) MPa for Zirprime with P<.001 for all 3 comparisons. After 200 hours at 134°C and 0.2 MPa, some tetragonal crystals transformed to the monoclinic phase. The relative XRD peak intensity of the monoclinic to tetragonal crystal phases increased from 0.07 to 1.82 for Lava, from 0.06 to 2.43 for Zirkonzahn, and from 0.05 to 0.53 for Zirprime. After 28 hours at 180°C and 1.0 MPa, all Lava and Zirkonzahn specimens spontaneously fractured during aging. The Noritake specimens were intact after 48 hours, and the flexural strength showed no significant change, 1156 (87.6) MPa to 1122 (108) MPa. The flexural strength decreased with an increase in the monoclinic phase. SEM micrographs revealed a transformed layer on the fracture surfaces.
Hydrothermal aging of Y-TZP can cause significant transformation from tetragonal to monoclinic crystal structure, which results in a statistically significant decrease in the flexural strength of thin bars. Although the strengths of all 3 Y-TZP materials are higher than other materials used for ceramic restorations, there are notable differences among them.
The Journal of prosthetic dentistry 10/2012; 108(4):223-30. · 1.22 Impact Factor
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ABSTRACT: Evidence is limited on the efficacy of zirconia-based fixed dental prostheses.
The purpose of this systemic review was to assess zirconia-based FDPs in terms of survival and complications.
Searches performed in PubMed databases were enriched by hand searches to identify suitable publications. The keywords used were: "zirconia" and "fixed dental prosthesis," "zirconia" and "crown," "zirconia" and "fixed partial denture" and "humans," "zirconia" and "crown" and "humans," "crown" and "all-ceramics," and "fixed partial denture" and "all-ceramics". Titles and abstracts were read to identify literature that fulfilled the inclusion criteria. Only peer reviewed clinical studies published in the English language from January 1999 through June 2011 were included.
Twelve clinical studies based on zirconia, framework design, and porcelain veneering technique met the inclusion criteria. Of the studies identified, 1 was a randomized clinical study with 3-year follow-up results; the others were cohort prospective studies. Clinical complications included chipping of veneering porcelain, abutment failure, and framework fracture. One study investigated pressed ceramics as the veneering material and found no chipping of veneering porcelain after 3 years.
Short term clinical data suggest that zirconia-based fixed dental prostheses may serve as an alternative to metal ceramic fixed dental prostheses in the anterior and posterior dentition.
The Journal of prosthetic dentistry 03/2012; 107(3):170-7. · 1.22 Impact Factor
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ABSTRACT: Attachments for mandibular overdentures may not allow for adequate freedom of rotation.
The purpose of this study was to subject 3 commonly used stud types of resilient attachments to rotation and to measure and compare the degree of rotation that occurs before the attachments bind.
Three stud attachments (ERA, Locator Extended Range, O-Ring System) with their corresponding metal housings were evaluated, first for a single implant system and secondly for a 2-attachment parallel implant system for the mandibular arch. Both the manufacturers' most and least retentive components were tested in each system. In the Locator system, the medium retention (3 lbs) for the standard is the most retentive of the extended range. A total of 60 test specimens, 5 per group, were fabricated. The attachments were connected to a 115-mm rod and attached to a testing device composed of a base, implant analogs, and a vertical plate holding graph paper. A free-sliding plastic block, which supported the metal rod parallel to the base, was removed to release the rod. The distance the rod fell was photographed and input into a computer with software designed to measure linear movement. Three-way ANOVA with heteroscedasticity consistent standard errors was used for data analyses (α=.05).
Significant differences found among the most retentive components showed that the Locator had a greater freedom of rotation than the ERA (P=.001). The most retentive components in all systems showed that 1 attachment had a greater freedom of rotation than 2 (P=.005). When testing the least retentive components, all systems were significantly different (P<.003), with the freedom of rotation ranking being O-Ring System > Locator Extended Range > ERA. For all 3 systems, the least retentive components showed the most freedom (P≤.008).
The least retentive components offer greater rotation than the most retentive components for all attachment systems tested and for both single and double attachments. Using the most retentive components, the Locator Extended Range attachment allows greater rotation than does the ERA for both single and double attachments. Using the least retentive components, the ORS attachment allows the most rotation and ERA the least for both single and double attachments. Using the most retentive components, one attachment allows greater rotation than does 2 attachments for the attachment systems evaluated.
The Journal of prosthetic dentistry 08/2011; 106(2):78-86. · 1.22 Impact Factor
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ABSTRACT: Heat-pressed ceramics to metal alloys and zirconia have been available for some time. However, information regarding their shear bond strengths is limited.
The purpose of this study was to evaluate the shear bond strengths of heat-pressed and layered ceramics with regard to their corresponding high-noble alloy and zirconia cores.
Forty cylinders (approx. 5 mm in diameter) of high-noble alloy (Olympia) were cast and divided into 4 groups (n=10). Metal cylinders were veneered with ceramics to produce shear test specimens: Group PMI with IPS InLine POM; Group LMI with IPS InLine; Group PMC with Pulse press-to-metal; and Group LMC with Authentic Pulse Metal ceramic. Forty cylinders (approx. 5 mm in diameter) of zirconia (Lava) were obtained and divided into 4 groups (n=10). These cylinders were veneered with ceramics to produce shear test specimens: Group PZI with IPS e.max ZirPress; Group LZI with IPS e.max. Ceram; Group PZV with VITA PM9; and Group LZV with VITA VM9. The veneering ceramics, 3 mm in thickness, were either pressed or layered to their corresponding cylinders. Thermal cycling was performed at 5°C and 55°C for 20,000 cycles with a 20 second dwell time. Shear bond strength testing was conducted in a universal testing machine, and the failure strengths were recorded. Fracture surfaces were characterized visually, under a stereomicroscope, and with a scanning electron microscope (SEM). Data were analyzed using rank-based Kruskal-Wallis and Mann-Whitney tests with Bonferroni correction to adjust for multiple comparisons (α=.05).
For metal ceramic specimens, the mean (SD) shear bond strengths ranged from 37.8 (20.6) MPa to 66.4 (22.1) MPa. There were significant differences between Groups PMI and PMC and between Groups LMI and PMC, in which Groups PMI and LMI had significantly higher strength values than Group PMC (P=.041). For zirconia ceramic specimens, the mean (SD) shear bond strengths ranged from 30.03 (9.49) MPa to 47.2 (13.0) MPa, with Group LZV having a significantly higher shear bond strength value than Group LZI (P=.012). Half of the Group PZV specimens failed during thermal cycling, and Group PZV was, therefore, excluded from statistical analysis. For all shear bond strength testing specimens, cohesive failures in the veneering ceramics were observed.
For shear bond strength of veneering ceramics to high-noble alloy, there was no significant difference between pressing and layering with the same manufacturer. For shear bond strength of veneering ceramics to zirconia, there was no significant difference between the pressed and layered groups.
The Journal of prosthetic dentistry 07/2011; 106(1):29-37. · 1.22 Impact Factor
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ABSTRACT: This clinical report describes the treatment of an edentulous patient with previous radiation therapy to the base of the tongue. A computer-aided manufactured titanium framework was used to fabricate the implant-supported fixed complete denture and meet the functional and psychosocial needs of the patient.
The Journal of prosthetic dentistry 03/2011; 105(3):154-7. · 1.22 Impact Factor
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ABSTRACT: To evaluate the shear bond strengths of highly cross-linked denture teeth bonded to heat-polymerized poly(methyl methacrylate) (PMMA) or a light-polymerized urethane dimethacrylate (UDMA) denture base resin with or without a diatoric and with or without an acrylate bonding agent.
The denture base resins tested were Lucitone 199 (heat-polymerized PMMA) and Eclipse (light-polymerized UDMA). One hundred sixty mandibular central incisor denture teeth were divided into four groups (n = 40): group 1: ground surface as control; group 2: ground surface with diatoric; group 3: ground surface with bonding agent; group 4: ground surface with bonding agent and diatoric. Half of each group (n = 20) was processed with either heat- or light-polymerized resin. All specimens were treated with thermocycling for 1000 cycles, alternating between 5 and 55 °C with a dwell time of 30 seconds. Half the specimens in each group were treated with cyclic loading at 22 N for 14,400 cycles at 1.5 Hz. All specimens were tested with shear load to failure. Data were analyzed with student's t-test, 2- and 3-way ANOVA, and Dunnett's T3 method (p < 0.05).
Statistical analysis demonstrated no significant effect on shear bond strength from cyclic loading. For the Lucitone 199 (L) specimens, mean shear bond strengths and standard deviations were (N) 66.5 ± 28.4, 72.7 ± 31.5, 80.6 ± 17.1, and 76.9 ± 21.9 for groups 1L, 2L, 3L, and 4L, respectively. For the Eclipse (E) specimens, mean shear bond strengths and standard deviations were (N) 3.7 ± 1.2, 7.3 ± 3.3, 90.0 ± 20.7, and 94.2 ± 17.8 for groups 1E, 2E, 3E, and 4E, respectively. No statistically significant differences in shear bond strengths were noted for the Lucitone 199 groups (p = 0.11). Eclipse shear bond strengths were significantly higher in groups 3E and 4E than in groups 1E and 2E (p ≤ 0.05). In a 3-way ANOVA for groups 3 and 4, the shear bond strengths for the Eclipse specimens were significantly higher than the Lucitone 199 specimens (p = 0.01).
When evaluating the shear bond strength of IPN denture teeth to denture base resins, specimens using an acrylate bonding agent with the Eclipse (light-polymerized) resin yielded significantly higher shear bond strengths than all of the Lucitone 199 groups and the Eclipse resin groups without a bonding agent.
Journal of Prosthodontics 11/2010; 20(1):52-9. · 1.01 Impact Factor
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ABSTRACT: The rigidity of the major connector for partial removable dental prostheses (PRDP) has not been well defined. There is little scientific evidence to support specific standards relative to the dimensions of a casting and their effect on long-term function of the PRDP or the supporting tissues.
The purpose of this study was to compare in vitro the effects of load deflection of 5 clinically used mandibular major connector forms.
A partially edentulous dental cast of a patient with the mandibular anterior teeth remaining was used as the test model. Lingual plate (LP), continuous bar (CB), sublingual bar (SB), lingual bar (LB), and dental lingual bar (DLB) specimens (n=5) were waxed on identical refractory casts, then cast in cobalt base alloy and finished. Each specimen was placed on a custom test table and statically loaded in the contralateral second molar region with 500 g in the horizontal and vertical planes. Deflections were measured at the terminal abutment rest seat, anterior to the load. Comparisons between group means were evaluated using the Dunnett T3 method, assuming unequal variances, for all pairwise tests at a .05 significance level and for 95% confidence intervals for group mean differences. Differences within the groups for vertical versus horizontal deflections were compared using a paired t test and Bonferroni correction (alpha=.05 for all tests).
Horizontal deflection between LP and LB, CB and LB, and SB and LB were significant, with the first in each comparison having the least amount of deflection. A significant difference was also seen in the vertical deflection, with the first in each comparison observed to have deflected the least for LP versus CB, LP versus LB, LP versus DLB, CB versus DLB, LB versus DLB, and SB versus DLB. The amount of vertical deflection was significantly greater than the horizontal deflection for all 5 mandibular major connectors (P< or =.033).
In the horizontal plane, a significant difference in the amount of deflection was seen between the LP and LB, CB and LB, and LB and SB. In the vertical plane, the LP deflected significantly less than the CB, LB, and DLB. In addition, the DLB deflected significantly more in the vertical plane when compared to the CB, LB, and SB. All 5 mandibular major connectors had a significantly greater amount of vertical deflection as compared to horizontal deflection.
The Journal of prosthetic dentistry 09/2010; 104(3):182-90. · 1.22 Impact Factor
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ABSTRACT: Impression making remains a challenging procedure due to the potential for voids and tears, which may adversely affect the precise fabrication of indirect restorations.
The purpose of this study was to compare vinyl polysiloxane (VPS) impression materials using the 1-step impression technique for single and 2-unit crowns.
Twenty subjects provided informed consent, and two 1-step double-phase master impressions (1 of each material combination) were made of 25 crown preparations. A relatively new VPS material with heavy-body (HB) and light-body (LB) viscosities, which was defined as the experimental group (Imprint 3), was compared to a standard VPS with medium-body (MB) and light-body (LB) viscosities, which was defined as the control group (Aquasil Ultra). Stock trays were used to make a total of 40 master impressions. The order of impression making was randomized as related to the different groups. Impressions were rated visually by 2 evaluators (a clinician and a dental technician). The rating resulted in ordinally structured data for the outcome variables (alpha: excellent, no defects; bravo: acceptable, small defects; charlie: defects require impression to be remade; delta: unacceptable, defects at finish line). Definitive casts made of impressions rated as alpha or bravo were further rated by a dental technician, and that which was rated best was used for making the definitive crown.
Twenty-three (92%) of the experimental and 24 (96%) of the control impressions were rated as alpha or bravo by the evaluator (P=.57; McNemar's test for clustered paired proportions using GEE). All 25 dies in the definitive casts of both groups were rated as alpha or bravo by the dental technician. Fifteen dies were selected from the control group and 10 from the experimental group for the fabrication of the definitive crowns (P=.41; 1-sample binomial test for clustered data using GEE).
Within the limitations of this clinical study, there was no statistical difference in the clinical performance of the experimental and control VPS impression materials. (J Prosthet Dent 2009;102:179-186).
The Journal of prosthetic dentistry 10/2009; 102(3):179-86. · 1.22 Impact Factor
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ABSTRACT: Surgical guides may interfere with effective use of surgical instrumentation during implant placement in the posterior segments where interocclusal distance may be limited.
The purpose of this study was to measure and compare the accuracy of posterior implant placement using 3 precision surgical guides with varying occlusogingival heights, and to evaluate the difference in accuracy of implant placement through precision guides as compared to freehand placement.
Three groups of surgical guides were fabricated with occlusogingival heights of 4, 6, and 8 mm, respectively. A jig was fabricated to allow for accurate positioning in bone substitute blocks. Ninety implants were placed in the mandibular first molar site on a manikin. Thirty implants (Astra Tech AB) were placed for each group, with 15 through the guide and 15 freehand. Distances between a reference implant and each placed implant were measured at both implant and abutment levels using a coordinate measuring machine. Apex position and angular discrepancy were calculated using the coordinates of the centers of the implant platform and of the occlusal aspect of the abutment. Data was assessed using 2-way ANOVA (alpha=.05).
Two-way ANOVA demonstrated that guide height did not significantly affect the accuracy of the implant position. The distance from the reference point to the point of measurement was significantly smaller for placement through the guide compared to freehand placement at both implant (P<.001) and abutment levels (P<.001). The angular discrepancy was also significantly smaller for placement through the guide (P<.001).
Precision surgical guides with 4-mm occlusogingival height allow placement as accurate as precision guides with 8-mm height. Placement through the guide reproduced the target position more accurately than freehand insertion.
The Journal of prosthetic dentistry 06/2009; 101(6):372-81. · 1.22 Impact Factor
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ABSTRACT: Flexural and shear strength between ZrO(2) cores and veneering porcelains require investigation to facilitate clinical use.
The purpose of this study was to assess the strength of ZrO(2) and a high-noble alloy with corresponding porcelains.
Forty rectanglar (12 x 10 x 3 mm) and 20 cylindrical (5 x 5 mm) specimens of ZrO(2) (Lava) and high-noble alloy (Olympia) were fabricated for 4-point flexural testing and shear testing. IPS d.SIGN veneering porcelain for high-noble alloy and Lava Ceram, 2 mm thick, were fired, joining the 2 corresponding rectangles of high-noble alloy and ZrO(2) to create flexural test specimens. The same types of veneering porcelains, 3 mm in thickness, were fired on 1 side of the corresponding high-noble alloy and ZrO(2) cylinders to produce shear specimens. The flexural and shear specimens were divided into 4 groups (n=10); metal ceramic and ZrO(2) with and without thermal cycling. Thermal cycling was performed at 5 degrees C and 55 degrees C for 5000 cycles with a 20-second dwell time. Flexural and shear tests were performed using a universal testing machine. Fractures were characterized using a stereomicroscope and SEM. Data were analyzed with a 1-way ANOVA and Tukey HSD post hoc test (alpha=.05).
The ANOVA revealed a significant difference among flexural groups (P=.008) and among shear groups (P<.001). In flexure, the Tukey HSD post hoc test revealed a significant difference (P=.005) between metal ceramic thermal cycled and ZrO(2) thermal cycled groups, with a higher value of 91.01 (22.33) MPa for the metal ceramic group. In shear, the Tukey HSD post hoc test revealed a significant difference between metal ceramic and ZrO(2) groups, with a higher value of 82.00 (22.49) MPa for the metal ceramic group. Thermal cycling did not have a significant effect on flexure or shear strength. ZrO(2) specimens failed cohesively within the veneering porcelain.
There were no significant differences among the groups in flexure, except between thermal cycled metal ceramic and ZrO(2) groups. There was a significant difference between the metal ceramic and ZrO(2) groups in shear. Thermal cycling did not have a clear effect among different groups in both tests.
The Journal of prosthetic dentistry 11/2008; 100(4):274-84. · 1.22 Impact Factor
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ABSTRACT: Identification of etiological factors is essential for successful management of tooth wear. In many cases, the diagnosis may be complicated because of the multiple etiologic factors which may confound the clinical appearance of tooth wear. Comprehensively addressing all of these factors is paramount to the long-term success of patient management.
Practical procedures & aesthetic dentistry: PPAD 06/2008; 20(4):220.
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Ariel J Raigrodski
Journal of Esthetic and Restorative Dentistry 02/2008; 20(4):215-7. · 0.99 Impact Factor
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ABSTRACT: Porcelain laminate veneers have been proven to be a successful treatment modality for maxillary incisors in clinical practice and in controlled clinical studies. However, the data in clinical studies on the success of veneers for restoring mandibular incisors are limited. Clinically, the successful restoration of mandibular incisors with porcelain laminate veneers is one of the more challenging procedures in all of esthetic restorative dentistry. Limited coronal dimensions, the small amount of enamel available for bonding (particularly in the cervical areas), materials and techniques for the bonding procedures, and the response of the tooth-veneer complex to forces generated during the incisal loading in both functional as well as parafunctional contacts must be considered as potential sources of success or failure. This Critical Appraisal reviews three recent scientific articles to shed some light on these issues and, as in all research endeavors, leads the reader to identify additional areas of concern that might stimulate further scientific inquiry. The first publication studied predictors for enamel thickness for mandibular incisors. The second examined bonding protocols for exposed dentin and suggested immediate dentin sealing. The third paper addressed fracture behavior of mandibular incisors restored with porcelain laminate veneers in vitro.
Journal of Esthetic and Restorative Dentistry 02/2008; 20(4):276-81. · 0.99 Impact Factor
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ABSTRACT: Controversy persists regarding the treatment planning criteria for young adult patients in need of esthetic restorations. The trend of conservative treatment modalities continues to become widely acknowledged. One of the conservative treatment modalities is porcelain laminate veneers (PLVs). PLVs not only provide suitable esthetics but also reliable functional strength. This article presents two anterior esthetic cases to demonstrate a conservative treatment planning approach and its application as a nontraditional solution for young adult patients. It is recommended that a conservative approach be used wherever possible as an alternative to treatment options that may aggressively sacrifice tooth structure as well as the health of the supporting tissues. CLINICAL SIGNIFICANCE: By using a conservative approach to treatment with porcelain veneers, long-lasting, esthetic, and functional results may be achieved. Sacrificing as little tooth structure as possible and conserving the supporting tissues will facilitate prospective treatments for young adult patients.
Journal of Esthetic and Restorative Dentistry 02/2008; 20(4):223-36; discussion 237-8. · 0.99 Impact Factor
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ABSTRACT: Complex restorative cases require difficult clinical decisions regarding the final esthetic outcome in which the operator must visualize the definitive restorative position of the teeth. These critical decisions need to be made before treatment is rendered. Communicating these decisions to the patient and the treatment team are crucial prior to achieving clinical success. The esthetic template is the conduit for providing excellent communication. The selection of the appropriate esthetic template is based on four sequential decisions: (1) dentofacial analysis, (2) blueprint development, (3) matrix management, and (4) template application. When utilizing an esthetic template, the clinician must know where the teeth should be placed based on a dentofacial analysis. The dentofacial analysis must then be communicated to the laboratory, and then a blueprint is developed from the diagnostic casts. A matrix is then fabricated from the blueprint and then related back to the existing dentition. The esthetic template is an invaluable communicator that can be utilized in office, with the patient at home, or even within the multidisciplinary treatment team. Clearly, the effective use of esthetic templates demonstrates a reversible way to visualize difficult esthetic decisions before any irreversible procedures are completed. Esthetic templates are a physical means of communication that provide the patient, technician, and multidisciplinary team an instrument to predictably manage complex restorative cases. The purpose of this article is to present a rationale for esthetic template selection and management of several techniques for complex restorative cases. CLINICAL SIGNIFICANCE: Complex restorative cases require difficult clinical decisions regarding the final esthetic outcome in which the operator must visualize the definitive restorative position of the teeth. The use of an esthetic template commensurate with a rationale for selection enables the operator, patient, and entire interdisciplinary team to visualize the final esthetic outcome.
Journal of Esthetic and Restorative Dentistry 02/2008; 20(4):239-48; discussion 249-50. · 0.99 Impact Factor
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ABSTRACT: Many different restorative materials are currently available for use in modern dentistry. Clinicians and dental technicians should be able to choose the most suitable materials for each patient based on research, anecdotal evidence, clinical experience, as well as patient's expectations and desires. The purpose of this article is to share the challenges presented in full-mouth rehabilitation and to describe the considerations in selecting three different restorative materials to achieve a successful restoration in terms of biomechanics, function, and esthetics. CLINICAL SIGNIFICANCE: Interdisciplinary treatment planning, knowledge of available restorative materials, sequencing treatment modalities, and adequate communication between all parties involved are key to a successful treatment outcome when pursuing full-mouth restorative rehabilitation.
Journal of Esthetic and Restorative Dentistry 02/2008; 20(4):251-63; discussion 264-5. · 0.99 Impact Factor
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Practical procedures & aesthetic dentistry: PPAD 10/2007; 19(8):511-2.
