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International Journal of Dentistry 2023Porcelain-veneered zirconia (PVZ) restorations are increasingly used due to their optimal esthetics and high strength. However, chipping of porcelain limits the...
INTRODUCTION
Porcelain-veneered zirconia (PVZ) restorations are increasingly used due to their optimal esthetics and high strength. However, chipping of porcelain limits the application of PVZ restorations. The aim of this study was to assess the shear bond strength (SBS) of colored and sandblasted zirconia to ceramic veneers fabricated by the pressing and layering techniques.
MATERIALS AND METHODS
Sixty cubic zirconia specimens (10 × 10 × 2 mm) were assigned to three groups according to their surface treatment: (I) control, (II) sandblasting with 50 m alumina particles (S), and (III) coloring (C). Each group was subsequently divided into two subgroups according to the porcelain-veneering technique: (I) layering (L) and (II) pressing (P). The specimens underwent 10,000 thermal cycles between 5 and 55°C, and their biaxial SBS was measured in an electromechanical universal test machine (0.5 mm/min with 2.5 kN load cell). The failure mode was also assessed under a stereomicroscope. Three samples were randomly selected from each subgroup ( = 18) for examination of zirconia-phase transformation by X-ray diffraction (XRD). Two-way and one-way ANOVA followed by the post hoc Tukey test were used to analyze statistical differences among the groups and subgroups ( = 0.05).
RESULTS
The sandblasted zirconia with press porcelain (SP) subgroup showed the highest (24.40 ± 8.16 MPa) and the colored zirconia with press porcelain (CP) subgroup showed the lowest (13.76 ±3.62 MPa) SBS. All failures were cohesive. Rate of phase transformation in layered porcelain was significantly lower than that in pressed porcelain ( < 0.01).
CONCLUSION
The sandblasted group showed the highest and the colored group showed the lowest SBS; the layered group showed higher SBS than the pressed group.
PubMed: 37496833
DOI: 10.1155/2023/4949867 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Oct 2023This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser and analyze the interfacial microstructure between veneers and tooth...
OBJECTIVES
This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser and analyze the interfacial microstructure between veneers and tooth that irradiated by laser, by which experimental evidence could be provided to support the non-invasive removal of occlusal veneerby laser.
METHODS
Fresh mandibular premolars extracted for orthodontic requirements were collected for tooth preparation. Three kinds of ceramic materials (Vita Suprinity, Vita Mark Ⅱ, and Upcera Hyramic) were selected to fabricate occlusal veneer with different thicknesses (1.0, 1.5, and 2.0 mm). One week later, Er:Yag laser (2.5 W and 3.5 W) was used to irradiate and remove the occlusal veneer and recorded the timespan. After the removal operation, the micro-morphologies of samples were examined by scanning electron microscope.
RESULTS
Upcera Hyramic veneer failed to be removed (>20 min); the operation span at 2.5 W, Vita Suprinity (96.0 s±16.0 s) was longer than Vita MarkⅡ(84.5 s±19.5 s) in the 1.0 mm group (<0.05), and Vita Suprinity (246.5 s±13.5 s) was longer than Vita MarkⅡ(170.0 s±14.0 s) in the 1.5 mm group (<0.05). At 3.5 W, Vita Suprinity (381.0 s±24.0 s) was longer than Vita MarkⅡ(341.5 s±26.5 s) in the 2.0 mm group.
CONCLUSIONS
Increasing laser power could shorten the operation span and facilitate the removal of occlusal veneers with the same thickness and composition. The occlusal veneer was sustained when insufficient laser power was applied. With the same laser power and ceramic thickness, laser penetration could interfere with the integral of the ceramic structure when the laser interacted with the bonding layer. With the same ceramic composition and laser power, the operation span and laser power increased with the thickness of the occlusal veneer. However, the laser was incapable of removing occlusal resin veneer directly.
Topics: Lasers, Solid-State; Materials Testing; Dental Porcelain; Ceramics; Bicuspid; Dental Veneers
PubMed: 37805681
DOI: 10.7518/hxkq.2023.2023038 -
BMC Oral Health Jan 2024This is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. The aim of this trial was to compare the... (Randomized Controlled Trial)
Randomized Controlled Trial
Two‑year clinical performance of indirect restorations fabricated from CAD/CAM nano hybrid composite versus lithium disilicate in mutilated vital teeth. A randomized controlled trial.
TRIAL DESIGN
This is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. The aim of this trial was to compare the two-year clinical performance of partial indirect restorations fabricated from CAD/CAM nano-hybrid composite and ceramic lithium disilicate blocks using the modified USPHS criteria.
METHODS
In two parallel groups (n = 50 restorations), fifty participants having mutilated vital teeth with a minimum of two remaining walls were randomly enrolled in this trial and received indirect restorations of either nano-hybrid composite resin blocks (Brilliant, Coltene, Switzerland) or Lithium Disilicate (IPS Emax CAD). The restorations were assessed using modified USPHS criteria by two independent blinded assessors at baseline, six months, one-year and two years follow-up visits. Categorical and ordinal data were presented as frequencies and percentages. Categorical data were analyzed using the chi-square test. Ordinal data were analyzed using the Mann-Whitney U test for intergroup comparisons and Freidman's test followed by the Nemenyi post hoc test for intragroup comparisons. Numerical data were presented as mean and standard deviation values. They were analyzed for normality using the Shapiro-Wilk test. Data were found to be normally distributed and were analyzed using the independent t-test. The significance level was set at p ≤ 0.05 within all tests.
RESULTS
Forty-eight participants received the allocated intervention and completed the follow-up periods. There was a statistically significant difference between both tested materials for all USPHS criteria regarding Marginal integrity and Marginal discoloration at six-months Follow-up, but with no statistically significant difference at one- and two-year follow-up.
CONCLUSIONS
Both materials showed an acceptable, successful clinical performance along the two-years follow-up period.
CLINICAL RELEVANCE
The CAD/CAM nano-hybrid composite blocks are as reliable as Lithium disilicate for restoring mutilated vital teeth.
Topics: Humans; Ceramics; Computer-Aided Design; Dental Materials; Dental Porcelain; Inlays; Materials Testing
PubMed: 38233771
DOI: 10.1186/s12903-023-03847-6 -
The International Journal of... Nov 2023To evaluate the fracture-behavior of monolithic crowns made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; IniBal LiSi Block, GC Dental) and zirconia-reinforced...
PURPOSE
To evaluate the fracture-behavior of monolithic crowns made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; IniBal LiSi Block, GC Dental) and zirconia-reinforced lithium silicate (Celtra Duo, DeguDent; VITA Zahnfabrik) materials before and after cyclic fatigue aging.
MATERIALS AND METHODS
Four groups (n = 22/group) of CAD/CAM fabricated upper incisor crowns were produced. All crowns were luted on metal dies with an adhesive dual-cure resin cement (G-CEM LinkForce, GC Dental). Half of the crowns in each group (n = 11) were statically loaded until fracture, without aging. The remaining crowns were subjected to cyclic fatigue aging for 120,000 cycles (Fmax = 220 N) and then loaded statically until fracture. The fractured models were then visually examined. Scanning electron microsopy (SEM) and energy-dispersive spectroscopy (EDS) were used to evaluate the microstructure of CAD/CAM ceramic materials. The data were statistically analyzed with two-way ANOVA followed by the Tukey HSD test (α = .05).
RESULTS
Before cyclic aging, there was no statistically significant difference in load-bearing capacity among the four groups (P = .371). After cyclic aging, load-bearing capacity significantly decreased for all groups (P = .000). While the e.max CAD blocks had significantly higher load-bearing capacity (1061 ± 94 N) than both monolithic ceramic crowns (load-bearing capacities of the groups) (P < .05), no significant difference was obtained with the Initial LiSi Block group (920 ± 140 N) (P = .061).
CONCLUSIONS
The mechanical performance of monolithic ceramic crowns fabricated from lithium disilicate was befer than zirconia-reinforced lithium silicate after cyclic fatigue aging. Int J Prosthodont 2023;36:e29-e37.
Topics: Lithium; Dental Porcelain; Ceramics; Crowns; Silicates; Computer-Aided Design; Materials Testing; Dental Stress Analysis; Dental Restoration Failure
PubMed: 33625389
DOI: 10.11607/ijp.7207 -
Dental Materials Journal Nov 2023This study investigated the influence of different surface treatments on unfiring or firing zirconia-reinforced lithium silicate (ZLS) glass-ceramics. Celtra Duo and IPS...
This study investigated the influence of different surface treatments on unfiring or firing zirconia-reinforced lithium silicate (ZLS) glass-ceramics. Celtra Duo and IPS e.max CAD blocks were cut and process following manufacturer protocols. The specimen surface was treated with seven different protocols. Two ceramic blocks with the same surface treatment were bonded with luting agent and prepared for mini-interfacial fracture toughness tests (mini-iFT). The specimens were tested after 1-week storage. The data was statistically analyzed using two-way ANOVA and Dunnett's T3 comparison (α=0.05). The highest mini-iFT of both Celtra Duo unfired and fired was shown in the HF+S group, which was not significantly different from HF+S+UA. For IPS e.max CAD, the mini-iFT was higher in the groups treated with hydrofluoric acid. Additional adhesive after silane application did not significantly improve bonding effectiveness. Therefore, surface treatment with hydrofluoric acid and silane is recommended for both unfiring and firing ZLS glass ceramics.
Topics: Dental Porcelain; Lithium; Silanes; Hydrofluoric Acid; Dental Bonding; Surface Properties; Ceramics; Silicates; Materials Testing; Computer-Aided Design
PubMed: 37880135
DOI: 10.4012/dmj.2023-124 -
Cureus Oct 2023This study aimed to compare the wear resistance and color stability of fixed dental prostheses (FDPs) fabricated using two different materials: zirconia veneered with...
OBJECTIVE
This study aimed to compare the wear resistance and color stability of fixed dental prostheses (FDPs) fabricated using two different materials: zirconia veneered with feldspathic porcelain and polyetheretherketone (PEEK) veneered with indirect composite. The assessment included samples subjected to thermocycling and wear simulation.
METHODS
Two groups of FDPs were examined: one made of zirconia veneered with feldspathic porcelain (control and thermocycled) and the other made of PEEK veneered with indirect composite (worn and thermocycled). The samples were evaluated for wear resistance, antagonist wear, and color stability. Computer-aided design (CAD) software and a digital spectrophotometer were used for analysis.
RESULTS
Zirconia veneered with porcelain demonstrated higher wear resistance compared to PEEK veneered with indirect composite. PEEK veneered with indirect composite exhibited significantly lower antagonist wear, indicating a protective effect on opposing teeth. There was no significant difference in color stability between the two groups, even after subjecting them to thermocycling and wear simulation.
CONCLUSION
The study concludes that FDPs fabricated with PEEK veneered with indirect composite may have lower wear resistance compared to zirconia veneered with porcelain. However, PEEK FDPs appear to be safer for antagonists due to reduced antagonist wear. Importantly, both materials exhibited similar color stability, making PEEK a viable alternative for FDPs when aesthetic appeal and antagonist protection are primary considerations.
PubMed: 37927753
DOI: 10.7759/cureus.46439 -
PloS One 2023The purpose of this study was to assess the effectiveness and practicality of erbium lasers in the removal of ceramic restorations and appliances from natural teeth and...
BACKGROUND
The purpose of this study was to assess the effectiveness and practicality of erbium lasers in the removal of ceramic restorations and appliances from natural teeth and dental implant abutments in clinical practice.
METHODS
A retrospective analysis was conducted, involving 29 clinical cases with a total of 52 abutments requiring the removal of various ceramic restorations. The analysis evaluated the clinical procedures performed, including the type and material of the prosthetic, the type of cement used, laser setting parameters, retrieval time, and retrieval success.
RESULTS
Out of the 52 abutments, 50 were successfully retrieved without causing any damage (>95%) using either an Er,Cr:YSGG laser (N = 6) or an Er:YAG laser (N = 46). In one case, a crown was partially sectioned to prevent any negative impact of laser irradiation on the adhesive strength between the post and tooth, and in another case, a fracture occurred during debonding. The restorations consisted of 13 lithium disilicate and 39 zirconia units, including six veneers, 38 single crowns, and three fixed partial dentures (FPDs). The retrieval time varied depending on the restoration type, material thickness, cement type, retention form/fitting of the abutment and restoration, ranging from 2.25 ±0.61 minutes for veneers, 6.89 ±8.07 minutes for crowns, to 25 ±10 minutes per abutment for FPDs. Removal of a zirconia crown required more time, 7.12±8.91 minutes, compared to a lithium disilicate crown, 5.86 ±2.41 minutes. The debonding time was influenced by the laser settings as well as materials and types of prosthesis.
CONCLUSIONS
Erbium lasers present a safe and effective alternative to invasive methods for removing ceramic restorations, without causing harm to the abutment or prosthesis. Laser-assisted debonding allows for recementation of the restorations during the same appointment, making it a conservative and viable option for ceramic crown retrieval in clinical settings.
Topics: Lasers, Solid-State; Erbium; Retrospective Studies; Crowns; Zirconium; Dental Porcelain; Ceramics; Dental Restoration Failure; Materials Testing
PubMed: 38096248
DOI: 10.1371/journal.pone.0295957 -
Journal of Prosthodontic Research Jul 2023This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using...
PATIENTS
This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using digital technology. An 83-year-old woman presented with gingival swelling around the maxillary right premolar. The swollen tooth was the abutment tooth of a cross-arch fixed partial denture. An intraoral scanner (IOS) and computer-aided design/manufacturing as digital technology were used to plan treatment with a double-crown-retained removable dental prosthesis. A metal-free prosthesis using zirconia for the primary crown and fiberglass-reinforced composite resin for the secondary crown was planned, and the patient consented to the treatment plan. After autotransplantation of a tooth as one of the abutments, the IOS was used to obtain digital scans of the prepared surface of the abutment teeth, opposing dentition, and occlusal relationships. First, primary crowns were milled using zirconia. Next, the intraoral scanner obtained a pick-up impression of the primary crowns, and secondary crowns were designed and milled from the fiber-reinforced composite. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis.
DISCUSSION
Digital technology offers many advantages such as efficient fabrication of double crowns, reduced material costs, improved biocompatibility, and good aesthetics of metal-free materials.
CONCLUSIONS
This clinical report describes the application of digital technology for the fabrication of a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia, resulting in patient satisfaction.
Topics: Female; Humans; Aged, 80 and over; Dental Prosthesis Design; Digital Technology; Zirconium; Crowns; Computer-Aided Design; Dental Porcelain
PubMed: 36031348
DOI: 10.2186/jpr.JPR_D_22_00064 -
PloS One 2023The durability of dental restorations is highly determined by an accurate marginal fit, which is in turn affected by the high temperature of porcelain firing....
The durability of dental restorations is highly determined by an accurate marginal fit, which is in turn affected by the high temperature of porcelain firing. Information is inadequate about the marginal adaptation of metal-ceramic restorations fabricated by soft metal milling technologies after repeated firings. This study aimed to compare the effect of repeated ceramic firings on the marginal fit of copings fabricated from cobalt-chromium through soft metal milling and a conventional nickel-chromium casting alloy. A single standard brass die was designed, machined, and scanned, based on which, 20 frameworks were designed and fabricated through either soft metal milling or conventional casting (n = 10 per group) and porcelain veneered. The vertical marginal fit of the metal copings was measured after 3, 5, and 7 firing cycles by using a digital microscope on 16 points around the finish line of the metal die at ×80 magnification. The data were analyzed through repeated measures ANOVA and independent t-test (α = 0.05). The marginal fit of neither metal group was significantly affected by the number of firing cycles (P = 0.747). However, the marginal discrepancy was statistically lower in the soft metal milling group than that in the casting group (P<0.001). Repeated porcelain firings did not significantly affect the marginal fit of either alloy and remained within the clinically acceptable range after firings. However, the milled alloy had superior marginal fit regardless of the number of firing cycles.
Topics: Dental Porcelain; Computer-Aided Design; Metal Ceramic Alloys; Chromium Alloys; Cobalt; Chromium; Dental Prosthesis Design
PubMed: 37874843
DOI: 10.1371/journal.pone.0275374 -
Journal of Dental Research Apr 2024The ever-increasing usage of ceramic materials in restorative dentistry necessitates a simple and effective method to evaluate flexural strength σ and fracture...
The ever-increasing usage of ceramic materials in restorative dentistry necessitates a simple and effective method to evaluate flexural strength σ and fracture toughness . We propose a novel method to determine these quantities using a bilayer specimen composed of a brittle plate adhesively bonded onto a transparent polycarbonate substrate. When this bilayer structure is placed under spherical indentation, tunneling radial cracks initiate and propagate in the lower surface of the brittle layer. The failure analysis is based on previous theoretical relationships, which correlate σ with the indentation force and layer thickness , and with and mean length of radial cracks. This work examines the accuracy and limitations of this approach using a wide range of contemporary dental ceramic materials. The effect of layer thickness, indenter radius, load level, and length and number of radial cracks are carefully examined. The accuracy of the predicted σ and is similar to those obtained with other concurrent test methods, such as biaxial flexure and 3-point bending (σ), and bending specimens with crack-initiation flaws (). The benefits of the present approach include treatment for small and thin plates, elimination of the need to introduce a precrack, and avoidance of dealing with local material nonlinearity effects for the measurements. Finally, the bilayer configuration resembles occlusal loading of a ceramic restoration (brittle layer) bonded to a posterior tooth (compliant substrate).
Topics: Materials Testing; Ceramics; Tooth; Dentistry; Dental Porcelain; Surface Properties
PubMed: 38410925
DOI: 10.1177/00220345231225445