Wear pattern-associated color stability of prefabricated composite veneers versus ceramic veneers.

PURPOSE: To evaluate the effect of different surface wear patterns on the discoloration tendency of two different prefabricated composite veneers and lithium disilicate ceramic veneers. MATERIALS AND METHODS: Discoloration tendency of two prefabricated composite resin veneers (Visalys Veneer Chairside (VIS) and Componeer (COM)) were compared to lithium disilicate veneers (IPS) in vitro. For each material, n = 60 samples were allocated to different test groups, and therefore each n = 10 specimens per group went through different wear tests. Mechanical abrasion tests were conducted using a toothbrush simulator, while erosive effects were carried out by citric acid (pH 1.57). A combination of abrasion and erosion tests was conducted as well. Four groups of wear tests were implemented: (1) abrasion, (2) abrasion followed by erosion, (3) erosion, and (4) erosion followed by abrasion. Another group was stored in distilled water as the control and one group was stained without a prior wear test. The staining solution was made from a coffee-tobacco brew. Specimens were stored in the coffee-tobacco solution for 21 days. Color measurements were performed with VITA Easyshade. To evaluate intramaterial discoloration, one half of every specimen was protected with foil. After storage in the staining solution, the first measurement was carried out on the 'protected' (untreated) surface, followed by a second measurement on the 'processed' (treated) discolored surface. Euclidean distance (ΔE) of discoloration was calculated according to the CIE-L*C*h* system. Data were analyzed with ANOVA followed by Games-Howell post hoc test and paired t-test (α = 0.05). RESULTS: Highest changes in ΔE were found in COM after 'abrasion' (ΔE -2.55) and 'erosion followed by abrasion' (ΔE -1.41). The discoloration tendency of VIS was affected by all wear tests, but changes were below the perceptive threshold (ΔE -0.19-0.32). Only abrasion followed by erosion affected the discoloration of IPS significantly, but findings were below the perceptive threshold, as well (ΔE -0.09). CONCLUSIONS: Prefabricated composite resin veneers revealed a low level of discoloration tendency after different wear tests. Nevertheless, in most cases the lowest discoloration tendency was found in specimens made from lithium disilicate.

Tratamiento integral de una adolescente con dentinogénesis imperfecta tipo I / Comprehensive treatment of an adolescent with type I dentinogenesis imperfecta

La dentinogénesis imperfecta (DI) es un desorden hereditario de carácter autosómico dominante, que se origina durante la etapa de histodiferenciación en el desarrollo dental y altera la formación de la denti-na. Se considera una displasia dentinaria que puede afectar ambas denticiones con una incidencia de 1 en 6000 a 8000 nacimientos. El tratamiento del pa-ciente con DI es complejo y multidisciplinario, supone un desafío para el odontólogo, ya que por lo general están involucradas todas las piezas dentarias y afec-ta no solo la salud buco dental sino el aspecto emo-cional y psicológico de los pacientes. Objetivo: des-cribir el tratamiento integral y rehabilitador realiza-do en una paciente adolescente con diagnóstico de DI tipo I. Relato del caso: Paciente de sexo femenino de 14 años, que concurrió en demanda de atención a la Cátedra de Odontología Integral Niños de la FOU-BA derivada del Hospital "Prof. Dr. Juan P. Garrahan" con diagnóstico de osteogénesis imperfecta tipo III (OI). Nunca recibió atención odontológica y el motivo de consulta fue la apariencia estética de sus piezas dentarias. Se realizó el examen clínico y radiográfico arrojando el diagnóstico de DI tipo I asociada a OI. Conclusión: El tratamiento rehabilitador de la DI tipo I en los pacientes en crecimiento y desarrollo debe estar dirigido a intervenir de manera integral y tem-prana para resolver la apariencia estética y funcio-nal, evitar las repercusiones sociales y emocionales y acompañar a los pacientes y sus familias (AU)

Dentinogenesis imperfecta (DI) is an autosomal dominant inherited disorder that originates during the histodifferentiation stage of tooth development and alters dentin formation. It is considered a den-tin dysplasia that can affect both dentitions with an incidence of 1 in 6000 to 8000 births. The treatment of patients with DI is complex and multidisciplinary, it is a challenge for the dentist, since in general all the teeth are involved and it affects not only oral health but also the emotional and psychological aspect of the patients. Objective: To describe the comprehen-sive and rehabilitative treatment carried out in an adolescent patient with a diagnosis of DI type I. Case report: A 14-year-old female patient, who required dental attention at the Department of Pediatric Den-tistry of FOUBA and was referred from the Hospital "Prof. Dr. Juan P. Garrahan" with a diagnosis of os-teogenesis imperfecta type III (OI). The patient never received dental care and the reason for consultation was esthetic appearance of her teeth. A clinical and radiographic examination was performed, resulting in a diagnosis of DI type I associated with OI. Conclu-sion: Rehabilitative treatment of DI in growing and developing patients will be aimed at early and com-prehensive intervention to resolve esthetic and func-tional appearance, avoid social and emotional reper-cussions and accompany patients and their families (AU)

Extended glaze firings for porcelain-veneered zirconia: Effects on the mechanical and optical behavior.

OBJECTIVE: This study evaluated the effect of dwell time (conventional or extended) and cooling protocol (fast or slow) of self-glaze firings on the mechanical (flexural strength and crack propagation) and optical (color and translucency) properties of a porcelain-veneered zirconia system. METHODS: Bilayer disc-shaped samples were prepared (Vita VM9 + In-Ceram YZ) and divided according to the final thermal treatment: glaze firing followed by slow cooling (furnace opening at 200 °C) (G-S) or fast cooling (furnace opening at 600 °C) (G-F, manufacturer-recommended protocol), extended glaze firing (15 min of dwell time) followed by slow cooling (EG-S) or fast cooling (EG-F), or no thermal treatment (CTRL). Porcelain roughness (Ra and Rz) was measured before and after glaze firings. Color (ΔE00) and translucency (TP00) alteration were also evaluated. Flexural strength was measured with the piston-on-three-ball test and crack propagation analysis was performed after Vickers indentations. Complementary analyzes of crystalline phase and scanning electron microscopy were carried out. RESULTS: Significant effect of dwell time was observed, with extended glaze leading to higher flexural strength and shorter crack lengths. Cracks of EG groups were observed to end in clusters of crystals. Color and translucency changed below perceptibility thresholds. All treatments led to a smoother surface and EG groups reached the lowest Rz values. An extra SiO2 peak was revealed in control and EG groups. No effect of cooling protocol was found. SIGNIFICANCE: Extended glaze firing was able to improve the resistance to crack initiation and propagation of porcelain-veneered zirconia without clinically perceptible changes in optical properties.

Marginal staining of ultra-thin ceramic veneers

The pigmentation of the resin cement at the tooth/ceramic interface compromises the esthetic and longevity of ultra-thin ceramic veneers. Aim: The aim of this study was to evaluate marginal staining of ultra-thin ceramic veneers cemented to intact enamel (non-prepared) and prepared enamel. Methods:Thirty-two (32) permanent central incisors were selected and randomly divided into two groups: intact enamel (IE) and prepared enamel (PE). The ceramic veneers of PE group were bonded to the prepared enamel and the ceramic veneers of IE group were cemented directly onto the intact enamel, with no preparation. Both preparation and cementation were standardized and performed by a single operator. Each group was subdivided into two subgroups (n = 8) with different immersion media - coffee and water. After an immersion period of 10 days, stereomicroscope images were made at 20X magnification of the mesial, distal, cervical and incisal surface of each specimen. Three blinded, trained and calibrated examiners evaluated the images of the resin cement interface of each surface. The data were subjected to KruskalWallis and MannWhitney statistical analysis. Immersion media and enamel preparation influenced the marginal staining of the tooth/ceramic interface. Results: When immersed in coffee, prepared interfaces presented greater marginal staining than unprepared interfaces. When immersed in water, there was no statistically significant difference between the groups. Conclusion: The cementation of ultra-thin ceramic veneers onto intact enamel is associated with less marginal staining and, consequently, improved esthetics

The effect of repetitive firings on the color of an alumina ceramic system with varying ceramic shade and thickness.

OBJECTIVE: The color of all-ceramic restorations is one of the main criteria to achieve esthetical success. Many factors such as ceramic thickness, condensation techniques, firing temperature, and numbers can affect the final color of restoration. The purpose of this study was to investigate the color changes in alumina-based ceramic system according to ceramic shade and thickness during the multiple firings. MATERIALS AND METHODS: Sixty disc-shaped specimens with two different veneering porcelain shades (A1 or A3), and with three different ceramic thicknesses (0.5, 1, or 1.5 mm), were fabricated from an alumina-based ceramic system. Multiple firings (3, 5, 7, or 9 firings) were performed, and color changes (ΔE00 ) were determined using a spectrophotometer. Repeated-measures ANOVA were used to analyze the data. The Duncan test was used for multiple comparisons (α = .05). RESULTS: The L*a*b* values of the specimens were affected by the number of firings (3, 5, 7, or 9), veneering ceramic shades (A1 or A3) and veneering ceramic thicknesses (0.5, 1, or 1.5 mm). Significant interactions were present between the number of firings, veneering ceramic shade, and veneering ceramic thickness for L* (p < .001), a* (p < .001), and b* (p < .001) values. CONCLUSIONS: No statistically significant color change was observed between 3rd and 9th firings. CLINICAL SIGNIFICANCE: Veneering ceramic shade, veneering ceramic thickness, and number of firings should be carefully considered to obtain an acceptable color match of the definitive restorations.

Effect of slow-cooling protocol on biaxial flexural strengths of bilayered porcelain-ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) disks.

OBJECTIVE: The present study investigated the biaxial flexural strengths of bilayered ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) disks with various layering porcelains veneered using a slow-cooling protocol. METHODS: Five porcelain materials (VITA VM9, Cercon Ceram Kiss, and Vintage ZR with experimental coefficient of thermal expansions; CTEs of 8.45, 9.04, and 9.61ppm/°C) were veneered on Ce-TZP/A disks and slow-cooled after firing to fabricate bilayered specimens (core-to-porcelain thickness: 0.8mm/1.5mm). Biaxial flexural strengths of the specimens with the porcelain layer in tension were tested based on the piston-on-three-ball method (ISO 6872:2008). The data were statistically analyzed using Weibull distribution and Fisher's exact test. RESULTS: Tensile stresses were observed in the entire porcelain layer while compressive stress at the surface of the Ce-TZP/A layer shifted to tensile stress at the interface between the materials. The cases of small CTE mismatches between the materials showed high Weibull characteristic strengths at the internal and external surfaces of the specimens, except the VM9 group (CTE: 9.0-9.2ppm/°C). The maximum tensile stress was observed on the surface of the porcelain layer, where cracks originated and continuously propagated into the Ce-TZP layer. The Ce-TZP/A fractured into two pieces for large CTE mismatches between the materials, resulting in significantly lower flexural strengths than those fracturing into three pieces for small CTE mismatches. SIGNIFICANCE: Flexural strengths and fracture behaviors of bilayered porcelain-Ce-TZP/A disks were influenced by the CTE mismatches, and a small CTE mismatch between the materials was preferred when using a slow-cooling protocol.

Effects of Lithium and Phosphorus on the Efficacy of a Liner for Increasing the Shear Bond Strength Between Lithium Disilicate and Zirconia.

PURPOSE: To evaluate the effect of the chemical formulation of liners on the shear bond strength (SBS) between lithium disilicate veneering ceramic and zirconia core. MATERIALS AND METHODS: Four experimental groups (n = 12) were designed according to liner composition: negative control group (lithium and phosphorus removed from the conventional liner), Li group (lithium added to the negative control group), P group (phosphorus added to the negative control group), and Li+P group as the positive control (conventional liner). After applying the liner, lithium disilicate was pressed on zirconia. Specimens were stored in distilled water (37°C, 24 h) before testing the SBS. To test the SBS, shear force was applied perpendicular to the lithium disilicate-zirconia interface. The differences in the SBS between the veneer lithium disilicate and zirconia substructure were evaluated with one-way ANOVA (significance level of 0.05). RESULTS: The presence or absence of lithium and phosphorus influenced the efficacy of the liner. The negative control and P groups showed mainly cohesive failures, and the Li group mainly showed mixed failures. Both adhesive and mixed failures were observed in the Li+P group. The groups including lithium showed significantly higher SBS than the negative control or Li+P group (p < 0.05). The group including phosphorus, which showed higher crystallinity, showed significantly lower SBS than the negative control and Li+P groups (p < 0.05). CONCLUSIONS: The differences in the composition of the liner can affect the wettability and reactivity, and as a result, the SBS was different.

Biaxial flexural strength of the bilayered disk composed of ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) and veneering porcelain.

OBJECTIVE: Herein we investigated the flexural strengths of bilayered ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) disks using different veneering porcelains. METHODS: Commercial (VITA VM9, Cercon Ceram Kiss, and IPS e.max Ceram) and experimental porcelains (Vintage ZR with coefficient of thermal expansions: CTEs of 8.45, 9.04, and 9.61ppm/°C) with various layer thicknesses (1.0, 1.5, and 2.0mm) were applied to Ce-TZP/A disks (0.8mm thickness, n=180). Biaxial flexural tests of the specimens with the porcelain layer in tension were evaluated based on the piston-on-three-ball method (ISO 6872: 2008). The calculated strengths were statistically analyzed using the two-parameter Weibull distribution with the maximum likelihood estimation. RESULTS: Although no significant differences were observed among the experimental porcelains, most specimens with the thinner layer of commercial porcelain showed higher Weibull characteristic strengths at the external surfaces than those with the thicker layer. Irrespective of the porcelain material, the thinner porcelain layer showed significantly higher strengths at the interface between the layers. Fracture origins were always observed at the bottom surface and continuously propagated into Ce-TZP/A substrates. The maximum tensile stress was located at the interface in specimens with the 1.0mm porcelain layer, except for IPS e.max Ceram. Porcelain delamination was dominant in the case of the higher CTE value and thicker layer thickness of the porcelain. SIGNIFICANCE: The calculated biaxial flexural strengths and the stress distributions for bilayered Ce-TZP/A disks were dependent on the porcelain materials. Optimum behavior was observed for a combination of a small CTE mismatch between the materials and a low core-to-porcelain thickness ratio.

Hemolasertherapy: A Novel Procedure for Gingival Papilla Regeneration-Case Report.

BACKGROUND: Interdental papilla is of major importance to patients' orofacial aesthetics, especially regarding anterior teeth as part of the smile's harmony. Loss of gingival tissue, which constitutes interdental papilla, forms what in odontology is called black spaces. This loss, besides affecting the smile's aesthetics, also provokes phonetic and functional damage. OBJECTIVE: The objective of the authors is to present the result of three clinical cases treated with an innovative technique called hemolasertherapy, which stimulates growth of gingival papilla and thus permanently fills in the black spaces. METHODS: The photobiomodulation therapy (PBMT) used a 660 nm diode laser (Laser Duo, MMO-São Carlos, SP, Brazil), punctual, contact mode in two steps: before the bleeding (first PBMT) and immediately after bleeding (second PBMT). Parameters used were power output: 100 mW, CW; diameter tip: 5 mm; spot area: 0.19 cm2; irradiation exposure time per point: 20 sec; 14 points per daily session; total of 2 sessions, with a 1-week interval; E: 2 J per point; E: per daily session, 28 J; irradiance per point: 0.52 W/cm2; fluence per point: 10.4 J/cm2. Total in two daily sessions: total energy: 56 J; total fluence: 294.75 J/cm, 560 sec total time. An in vitro preliminary study was simultaneously carried out to demonstrate what could happen at cellular level in hemotherapy clinical cases associated with PBMT laser application. RESULTS: This initial study demonstrated that the blood clot originated from the bleeding provoked in the gingival area is rich in mesenchymal stem cells. PBMT enables preservation, viability, and further differentiation, stimulating the return of gingival stem cells, which would support their survival and differentiation in the blood clot, thus favoring interdental papilla regeneration. CONCLUSIONS: Follow-up was done for a time span of 4-5 years and considered excellent with regard to papilla preservation.

Laser-assisted removal of all ceramic fixed dental prostheses: A comprehensive review.

OBJECTIVE: The aim of this comprehensive review was to assess the effectiveness of erbium lasers in the removal of all ceramic fixed dental prostheses (FDPs). OVERVIEW: Indexed databases were searched without language or time restriction up to and including December 2017 using different combinations of the following keywords: "lasers"; "phototherapy"; "crowns"; "prostheses and implants"; "inlays"; "ceramics"; "dental porcelain"; "zirconium"; "removal"; "debonding"; "fixed dental prostheses"; "veneers"; "laminates"; and "fixed bridge." All levels of available evidence including experimental studies, case reports and case series were included. Six clinical studies reporting a total of 13 cases and 6 experimental studies were included. Results from all studies showed that erbium lasers are effective reducing the shear bond strengths of all ceramic FDPs, in terms of easy removal of the restorations with none or minimal damage to teeth or ceramic surfaces. CONCLUSION: Laser-assisted removal of all ceramic FDPs is a promising treatment protocol. Further well-designed controlled clinical trials and longitudinal prospective studies are needed to determine the precise laser parameters and duration of irradiation that could be used for removal of ceramic restorations with varying thicknesses. CLINICAL SIGNIFICANCE: Benefits of lasers over mechanical instrumentation for crown removal encompass efficient restoration retrievability without restoration or teeth surfaces damages; and relatively easier and time effective procedure with no prerequisite for anesthetic agents. It is however imperative for clinicians to be well-trained and exhibit adequate knowledge regarding recommended power settings and laser-safety parameters with reference to interactions between light and different tissues and ceramics.

Influence of sodalite zeolite infiltration on the coefficient of thermal expansion and bond strength of all-ceramic dental prostheses.

In all-ceramic systems, a high incidence of veneer chip-off has been reported in clinical studies. Coefficient of thermal expansion (CTE) behaviour is one of the factors that may increase residual stress in the interface and influence the veneer/core bond strength. Therefore, this study aimed to evaluate the effect of sodalite zeolite-infiltration on the CTE behaviour and bond strength of different all-ceramic prostheses. The case-study groups were synthesized sodalite zeolite-infiltrated alumina (IA-SOD) and synthesized sodalite zeolite-infiltrated zirconia-toughened alumina (ZTA) (IZ-SOD), while the control groups were glass-infiltrated alumina (IA-glass) and glass-infiltrated ZTA (IZ-glass). Forty cylindrical-shaped samples measuring 5 mm in diameter and 10 mm in height were tested for CTE using a thermo-mechanical analyser machine, and forty disc-shaped ceramic samples measuring 12 mm in diameter and 1.2 ± 0.2 mm in thickness were prepared using specially designed stainless steel split mould and veneered by cylinder-shaped (2 mm high × 2 mm diameter) low-fusing porcelain (Vita VM7). The veneer/core samples were sintered and tested for shear bond strength using a high precision universal testing machine. Scanning electron microscope, stereo microscope, atomic force microscope, and energy-dispersive X-ray spectroscopy were used to investigate the structural characteristics of samples at the fracture surface. The collected data were analyzed with a one-way ANOVA and Tukey HSD test (α=.05). IZ-SOD revealed highest CTE and shear bond strength values, while the IA-glass revealed the lowest values than the other groups. There was no significant difference in CTE and bond strength among IZ-SOD, IA-SOD and IZ-glass samples (p>0.05). The experimental SOD zeolite-infiltrated samples revealed higher CTE mismatch and bond strength along with a more favourable mode of failure than did the commercial glass-infiltrated samples. Sandblast technique is considered as effective conditioning procedure for enhancing the surface roughness of SOD zeolite-infiltrated frameworks which subsequently improving the bond strength.

Effect of different aging methods on the mechanical behavior of multi-layered ceramic structures.

OBJECTIVE: To evaluate the effect of two aging methods (mechanical cycling and autoclave) on the mechanical behavior of veneer and framework ceramic specimens with different configurations (monolithic, two and three-layers). METHODS: Three ceramics used as framework for fixed dental prostheses (YZ-Vita In-Ceram YZ; IZ-Vita In-Ceram Zirconia; AL-Vita In-Ceram AL) and two veneering porcelains (VM7 and VM9) were studied. Bar-shaped specimens were produced in three different designs: monolithic, two layers (porcelain-framework) and three layers (porcelain-framework-porcelain). Specimens were tested for three-point flexural strength at 1MPa/s in 37°C artificial saliva. Three different experimental conditions were evaluated (n=10): control; mechanical cycling (2Hz, 37°C artificial saliva); and autoclave aging (134°C, 2 bars, 5h). Bi-layered specimens were tested in both conditions: with porcelain or framework ceramic under tension. Fracture surfaces were analyzed using stereomicroscope and scanning electron microscopy. Results were statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls tests. RESULTS: Only for AL group, mechanical cycling and autoclave aging significantly decreased the flexural strength values in comparison to the control (p<0.01). YZ, AL, VM7 and VM9 monolithic groups showed no strength degradation. For multi-layered specimens, when the porcelain layer was tested in tension (bi and tri-layers), the aging methods evaluated also had no effect on strength (p≥0.05). Total and partial failure modes were identified. SIGNIFICANCE: Mechanical cycling and autoclave aging protocols had no effect on the flexural strength values and failure behavior of YZ and IZ ceramic structures. Yet, AL monolithic structures showed a significant decrease in flexural strength with any of the aging methods.

Shear bond strength of composite resin bonded to preformed metal crowns for primary molars using a universal adhesive and two different surface treatments: an in vitro study.

AIM: This was to determine the shear bond strength of composite resin bonded to preformed metal crowns with a new adhesive. Buccal surfaces of the crowns were roughened by two different methods to increase retention. METHOD: Typodont mandibular second primary molars (38) were divided into two groups (19 per group). Preformed metal crowns were cemented to the teeth with glass-ionomer cement. To enhance retention, buccal surfaces of the crowns in group I were roughened with cross-cut carbide burs (SS White #56); crowns in group II were sandblasted (aluminium oxide, 50 µm). Scotchbond Universal Adhesive (3 M-ESPE) was used to bond composite resin to the crowns. A universal testing machine tested the maximum shearing force withstood by the veneered composite surfaces. RESULTS: Sandblasted crowns demonstrated significantly higher resistance (p = 0.001) to shearing force (324.4 N) than did the crowns that were roughened with a bur (234.2 N). CONCLUSION: Chairside veneering of composite resin to pretreated crowns could be a feasible, aesthetically pleasing, and an economical option in paediatric dentistry.

[Comparison of the shear bond strength by using nano silica sol to zirconia basement and veneer porcelain].

PURPOSE: To investigate the feasibility of using sol gel technique to produce thin layer nano silicon dioxide on zirconia ceramic surface and the effect of improving shear bond strength between zirconia and veneer porcelain. METHODS: The presintered zirconia specimen was cut into a rectangle block piece (15 mm×10 mm×2.5 mm), a total of 40 pieces were obtained and divided into 4 groups, each group had 10 pieces. Four different treatments were used in each group respectively. Pieces in group A (control group) were only sintered at 1450°C to crystallization; pieces in group B underwent 30% nano silica sol infiltration first and then were sintered at 1450°C to crystallization; piece in group C underwent crystallization first at 1450°C, then 30% nano silica sol infiltration and were sintered at 1450°C again; pieces in group D was coated by nano silica sol and then sintered at 1450°C to crystallization; ten rectangle block pieces (12 mm×8 mm×2 mm) in group E were made. Cylinder veneers 5 mm in diameter and 4 mm in height were produced in each group and the shear bond strength was tested. Data were statistically analyzed by SPSS 19.0 software package. RESULTS: The shear bond strength of the 5 group specimens were: (28.12±2.95) MPa in group A, (31.09±3.94) MPa in group B, (25.60±2.45) MPa in group C, (31.75±4.90) MPa in group D, (28.67±3.95) MPa in group E, respectively. Significant differences existed between the 5 groups, and group C had significant difference compared with group B and D. CONCLUSIONS：① Use of nano silicon sol gel on presintered zirconia surface to make thin layer of nano silicon dioxide can improve the shear bond strength between zirconia and veneer; ②Using nano silicon sol gel on crystallization zirconia surface to make thin layer of nano silicon dioxide will decrease the shear bond strength between zirconia and veneer; ③ Zirconia veneer bilayer ceramic has the same shear bond strength with porcelain fused to Ni Cr alloy; ④Use of sol gel technique to produce thin layer nano silicon dioxide on zirconia ceramic surface is feasible and can improve shear bond strength between zirconia and veneer porcelain.

Tiempo de vida de las restauraciones dentales libres de metal: revisión sistemática / Lifetime of metal-free dental restorations: a systematic review

En la actualidad existen muchos materiales dentales para la restauraciónestética, sin embargo, su tiempo de vida clínico no se conoce ampliamente. Objetivo: Identificar las publicaciones recientes de los materiales de restauración libre de metal que incluyan estudios clínicos. Metodología: La búsqueda sistemática de la literatura se realizó en bases de datos de PubMed y SciELO; se consideraron publicacionesdel 2010-2015 y que fueran investigaciones clínicas exclusivamente.Las palabras clave utilizadas fueron: Veneer crowns, dental restorationsfree metal, metal free crowns, aesthetic crowns y restauraciones libres de metal, coronas de silicato de litio, tipos de cerámicas. Resultados: Se revisaron 40 artículos y 20 cumplieron con los criterios de selección para la revisión bibliográfica. Todas las restauraciones protésicas libres de metal muestran un desempeño clínico muy similar a los tres años. Las restauraciones de zirconia y disilicato de litio por CAD mostraronel mejor éxito clínico. Conclusión: El éxito clínico de las restauracioneslibres de metal de esta revisión de la literatura muestra que van de un92.7 al 100 por ciento a tres o más años de seguimiento...

Influence of Light Irradiation Through Zirconia on the Degree of Conversion of Composite Cements.

PURPOSE: To assess the light irradiance (LI) delivered by two light-curing units and to measure the degree of conversion (DC) of three composite cements and one flowable composite when cured through zirconia or ceramic-veneered zirconia plates with different thicknesses. MATERIALS AND METHODS: Three dual-curing composite cements (Clearfil Esthetic Cement, Panavia F2.0, G-CEM LinkAce) and one light-curing flowable composite (G-aenial Universal Flo) were investigated. Nine different kinds of zirconia plates were prepared from three zirconia grades (YSZ: Aadva and KATANA; Ce-TZP/Al2O3: NANOZR) in three different thicknesses (0.5- and 1.5-mm-thick zirconia, and 0.5-mm-thick zirconia veneered with a 1.0-mm-thick veneering ceramic). Portions of the mixed composite cements and the flowable composite were placed on a light spectrometer to measure LI while being light cured through the zirconia plates for 40 s using two light-curing units (n = 5). After light curing, micro-Raman spectra of the composite films were acquired to determine DC at 5 and 10 min, 1 and 24 h, and at 1 week. RESULTS: The zirconia grade and the thickness of the zirconia/veneered zirconia plates significantly decreased LI. Increased LI did not increase DC. Only the Ce-TZP/Al2O3 (NANOZR) zirconia was too opaque to allow sufficient light transmission and resulted in significantly lower DC. CONCLUSION: Although zirconia-based restorations attenuate the LI of light-curing units, the composite cements and the flowable composite could be light cured through the YSZ zirconia. LI is too low through Ce-TZP/Al2O3 zirconia, necessitating the use of self-/dual-curing composite cements.

Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical elemental shifts recorded in the veneering ceramic did not suffice to draw definitive conclusions regarding potential chemical interaction of the veneering ceramic with zirconia. Sandblasting damaged the zirconia surface and induced phase transformation that also resulted in residual compressive stress. Difference in CTE of zirconia versus that of the veneering ceramic resulted in an unfavorable residual tensile stress at the zirconia-veneering ceramic interface.

Comprehensive Risk-Based Diagnostically Driven Treatment Planning: Developing Sequentially Generated Treatment.

The clinical example presented in this article demonstrates a risk-based, diagnostically driven treatment planning approach by focusing on 4 key categories: periodontal, biomechanical, functional, dentofacial. In addition, our unique approach allowed the comprehensive clinical management of a patient with complex restorative needs. A full-mouth rehabilitation was completed sequentially without sacrificing the amount of dentistry necessary to restore health, comfort, function, and esthetics. The result exceeded the patient's expectation and was made financially possible by extending treatment over numerous years.

[Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

PURPOSE: In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. METHODS: The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. RESULTS: The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(P<0.05). SEM and EDS showed that the interface of group C sintered tightly and elements permeated on both sides of the interface. CONCLUSIONS: The diatomite-based substrate ceramics combines better with E-max porcelain veneer.