Review of the Modern Dental Ceramic Restorative Materials for Esthetic Dentistry in the Minimally Invasive Age

Two-year clinical performance of indirect resin composite restorations in endodontically treated teeth with different cavity preparation designs: a randomized clinical trial

TRIAL DESIGN

This is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. This study aimed to assess whether the cavity design could affect the clinical performance of the CAD/CAM generated indirect resin composite restoration in endodontically treated teeth (ETT) evaluated using the Modified USPHS criteria after a two-year follow up.

METHODS

A total of 30 participants who underwent endodontic treatment for MOD cavities in permanent molars were divided randomly into two parallel groups (n = 30 restorations) according to the performed cavity design to group 1 in which there was no cuspal reduction (inlay) and group 2 in which cuspal reduction was performed (overlay). All pulp chambers were filled with bulk fill flowable composite, and the cavities were prepared following the criteria of the cavities for indirect restorations and restored using nano-hybrid composite resin blocks (Brilliant, Coltene, Switzerland). The restorations were evaluated using the modified USPHS criteria at baseline, six months, one-year and two years follow-up visits. For qualitative data, frequencies (n) and percentages (%) were used to display the data, while mean and standard deviation (SD) were used for quantitative data. The normality of the data was evaluated using the Shapiro-Wilk and Kolmogorov-Smirnov tests. For every test, P ≤ 0.05 was used as the significance threshold.

RESULTS

Twenty-six individuals completed the follow-up period after receiving the assigned intervention.The inter-group comparison showed that, at the 6- months and 12- months observation points, the overlay design had significantly better marginal adaptation, less incidence of discoloration or tooth/restoration fracture, and similar marginal integrity and caries incidence to the inlay design. After 24- months, the overlay design still had better marginal adaptation, less incidence of discoloration or tooth/restoration fracture and less caries incidence in comparison to the inlay design, while there was no difference in the marginal integrity between either design.

CONCLUSIONS AND CLINICAL RELEVANCE

Cuspal reduction in endodontically treated teeth showed better clinical performance than the cusp preservation thus, the former is more reliable.

Advances in ceramics for tooth repair: From bench to chairside

OBJECTIVES

To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application.

DATA, SOURCES AND STUDY SELECTION

Researches on chemical composition, biomechanical behaviors, optical properties, bonding strategies and fabrication methods were included. The search of articles was independently conducted by two authors in the PubMed, Scopus, Medline and Web of Science.

CONCLUSIONS

Dental ceramics have shown significant advancements in terms of esthetics and function. However, improving fracture toughness without compromising optical properties remains a challenge. Repairing fractured zirconia or glass-matrix ceramic prostheses with the same material is difficult due to the sintering process. Developing innovative bonding techniques that provide strong and long-lasting bonding strength between ceramics and tooth structures poses a recurring obstacle.

CLINICAL SIGNIFICANCE

Despite the emergence of dental ceramics and fabrication techniques, certain limitations such as susceptibility to brittleness and fracture still exist. Therefore, the current review provided valuable information around the advanced dental ceramics in tooth repair. The laboratory test data and the clinical outcome are also presented in details, aiming to guide clinicians in making informed decisions regarding ceramic restorations.

Biomechanical consideration in tooth-supported glass-ceramic restorations: A systematic review and meta-analysis of survival rates and irreparable failures

STATEMENT OF PROBLEM

Knowledge on the biomechanical behavior of glass-ceramics, their survival rate over time, and their potential failures is essential for decision-making in clinical practice. Systematic reviews and meta-analysis of their survival rates and irreparable failures are lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the survival rates and irreparable failures of various monolithic glass-ceramic dental restorations to help determine biomechanical indications.

MATERIAL AND METHODS

A comprehensive literature search was conducted across the PubMed, Scopus, Web of Science, and EMBASE databases based on the population, intervention, comparison, and outcome (PICO) question, risk of bias assessment, data extraction, subgroup analysis, and meta-analysis. Both randomized and nonrandomized clinical trials that reported survival rate and irreparable failure were screened. The risk, with a 95% confidence interval, was calculated by using the Mantel-Haenszel method.

RESULTS

A total of 46 articles met the inclusion criteria: 8 for laminate veneers, 20 for partial coverage restorations, 11 for single crowns, and 6 for fixed partial dentures, encompassing 1715 participants rehabilitated with 4209 restorations. The estimated cumulative survival rate for partial coverage restorations was 90% over an average span of 6.2 years, with an irreparable failure occurrence of n=5.9. Laminate veneers had a survival rate of 90.2% over 6.5 years, with an irreparable failure occurrence of n=8.2. Single crowns had a survival rate of 96% over 4.6 years and an irreparable failure of n=2.7. Conversely, fixed partial dentures had a survival rate of 76.1% over 6.5 years with an irreparable failure of n=5.2.

CONCLUSIONS

Glass-ceramic materials demonstrate relatively high survival rates, indicating that they provide a safe and reliable option for partial coverage restorations, laminate veneers, and single crowns. However, fixed partial dentures had a higher proportion of irreparable failures and a lower survival rate, and caution is required.

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.

The effect of in-office bleaching agents on the Vickers hardness and surface topography of polished and unpolished CAD/CAM composite materials

In-office bleaching, using hydrogen peroxide, is effective to remove dental enamel stains. However, bleaching agents can deteriorate surface properties of CAD-CAM materials. This in vitro study aimed to investigate the effect of in-office bleaching agents on Vickers hardness and surface topography of polished and unpolished dental CAD-CAM composite materials (Grandio blocs, Lava Ultimate, BRILLIANT Crios, Cerasmart), and a polymer-infiltrated ceramic network block (Vita Enamic). The specimens were randomly divided into two groups: unpolished or polished. The micro-hardness and surface topography of each group were measured before bleaching, after a 60 min bleaching period, and 24-h and one-month post-bleaching. In-office bleaching significantly influenced the Vickers hardness of both the polished and unpolished CAD/CAM composite blocks, with Vita Enamic exhibiting the least hardness stability among all groups. Furthermore, in-office bleaching significantly influenced the surface roughness of unpolished CAD/CAM composite blocks. There was a significant difference in hardness reduction between the polished and unpolished specimens for most of the investigated materials at different time points. The bleaching did not influence the surface roughness of the investigated polished group, except for Vita Enamic and Lava Ultimate. However, it did influence the surface roughness of the investigated materials in the unpolished group.

A Comparative Evaluation of Enamel Wear Against Different Surface Finished Ceramics: An In Vitro Study

BACKGROUND

An essential factor in the clinical acceptability of all ceramic restorations is the degree of tooth enamel wear. Wear of human enamel has been shown to produce traumatic occlusion, loss of vertical dimension, supra eruption of opposing teeth, periodontal disintegration, and temporomandibular dysfunction. To assess and compare enamel wear against two different ceramics (IPS Empress and Zirconia) and against three different ceramic surface treatments (autoglazed, overglazed, and polished).

METHODS

Zirconia and IPS Empress (Ivoclar Vivadent, Liechtenstein) ceramic samples totaled 30, of which 10 each underwent glaze, overglaze, or polishing with Diaglaze polishing paste. Using a horizontal pin on the disc machine, 60 mounted premolar tooth samples were produced and put through wear tests against ceramic discs. Prior to and following wear, the weight of the tooth samples was measured, and the results were then statistically analyzed using the student t-test, unpaired t-test, and analysis of variance (ANOVA). The qualitative data employed proportions, and the quantitative data used mean and standard deviation to express statistical information. The threshold of significance was set at 5% (α = 0.05).

RESULTS

The results for weight loss after 25,000 cycles for ceramic surfaces that had been overglazed were just a little bit greater than those for ceramic surfaces that had been autoglazed and polished. In each of the various subgroups, it was shown that the weight loss values obtained with polished ceramic after 25,000 cycles were significantly lower than those obtained with autoglazed and overglazed ceramic surfaces (P=0.001). When comparing the results produced by the two separate primary groups, IPS Empress and Zirconia, there was no statistically significant difference between the autoglazed, overglazed, and polished groups. While statistically significant difference was seen for each subgroup of IPS and Zirconia (p ≤ 0.01), particularly Zirconia glazed (1.227) with a highly significant p-value of 0.00.

CONCLUSION

The findings contribute to the understanding of the potential clinical implications of different ceramic materials and surface finishes in restorative dentistry, offering valuable insights for practitioners in their treatment decisions. Further research and clinical observations may be needed to corroborate these findings and guide evidence-based practices in dental restorations.

Post-fatigue fracture load, stress concentration and mechanical properties of feldspathic, leucite- and lithium disilicate-reinforced glass ceramics

Objective

To evaluate the mechanical properties of different CAD/CAM ceramic systems and the post-fatigue fracture and stress distribution when used as cemented crowns.

Materials and methods

Sixty (60) CAD/CAM monolithic crowns were milled using three different ceramic materials (FD - Feldspathic [Vita Mark II]), LE - Leucite-based ceramic [IPS Empress CAD] and LD - Lithium Disilicate [IPS e.max CAD]) and adhesively cemented on resin composite dyes. Specimens were stored in distillated water (37 °C) for 7 days. After, half of the crowns were submitted to immediate fracture load test while the other half was submitted to fatigue cycling. The average cement layer of approximately 80 μm was assessed using scanning electron microscopy (SEM). The average thickness was used in the three-dimensional (3D) Finite Element Analysis (FEA). For each ceramic material, the density, Poisson ratio, shear modulus, Young modulus, fracture toughness, and true hardness were assessed (n = 3). The data was used to assess the Maximum Principal Stress throughout 3D-FEA according to each material during load to fail and post-fatigue. Data were submitted to two-way ANOVA and Tukey test (α = 0.05).

Results

LD showed the highest compression load, density, shear modulus, Young modulus, fracture toughness and true hardness values. While LE presented the lowest mechanical properties values. There is no difference in the Poisson ratio between the evaluated ceramics.

Conclusion

LD was susceptible to aging process but presented stronger physicomechanical properties, showing the highest post-fatigue fracture load and highest stress magnitude.

Influence of dental prophylaxis procedures on the tooth veneer interface in resin-based composite and polymer-infiltrated ceramic veneer restorations: an in vitro study

OBJECTIVES

The aim of this study was to investigate the influence of dental prophylaxis cleaning procedures and artificial aging on veneers in human teeth. The external marginal and internal tooth veneer as well as the restoration surfaces were examined.

MATERIAL AND METHODS

Thirty-two extracted premolars were restored with resin-based composite (RBC) and polymer-infiltrated ceramic network (PICN) veneers. Artificial aging by alternating thermocycling and subsequent prophylaxis procedure (glycine-based powder air polishing or ultrasonic scaling) was conducted for five consecutive cycles. The external marginal interface was examined by height profile measurements and the internal interface was investigated using micro X-ray computed tomography. In addition, the surface texture of the veneer surface was analyzed using confocal laser scanning microscopy.

RESULTS

The application of both prophylaxis procedures resulted in a deepening of the marginal interface (10 µm ± 8 µm) for materials. Furthermore, the internal interface of PICN restorations showed marginal gaps after both treatments and artificial aging (16 µm ± 3 µm). In contrast to the RBC specimens, a significant increase in surface roughness was identified for PICN veneers after ultrasonic scaling.

CONCLUSIONS

The marginal and internal interface regions in veneers fabricated from PICN and RBC were affected by prophylaxis procedures. Furthermore, it may result in increased veneer surface roughness, especially in PICN and after ultrasonic scaling, which might affect bioadhesion and longevity.

CLINICAL RELEVANCE

After dental prophylaxis procedures, examination of the marginal and the internal interface as well as the veneer surface provides a precise insight into damage mechanisms and offers an assessment of longevity.

Fabrication of color-graded feldspathic dental prosthetics for aesthetic and restorative dentistry

OBJECTIVE

Feasibility investigation of natural teeth shades replication on dental prosthetics fabricated via functionally graded additive manufacturing (FGAM) using combination of feldspathic porcelain (FP) and yttrium aluminum garnet cerium (Y₃Al₅O_12:Ce, YAG:Ce) as a promising esthetic restoration option.

METHODS

Color-graded feldspathic crown fabrication parameter through FGAM method was comprehensively examined from the slurry rheology, cure depth, debinding to sintering temperature. Effect of light absorbent also checked towards overcuring reaction during UV exposure by the shape comparison. Lastly, the flexural bending strength measured following ISO 6872:2015 to assure the applicability. Applying the studied parameter, natural teeth shades then imitated and investigated by alteration of FP and FP + 0.1 wt% YAG:Ce (Y-FP). Generated color across the structure captured through mobile camera, interpreted through the CIELAB coordinate and the gradation confirmed by the color differences (ΔE₀₀) calculated using CIEDE2000 formula.

RESULT

Parameter study indicated that 70 wt% of FP slurry with 3 wt% dispersant and 0.2 wt% light absorbent is favored. It produces excellent flowability in our FGAM system with less overcuring justified by edge margin reduction from 95.65° to 90.00° after UV exposure on rectangle shapes masking. The obtain structure also offers adequate flexural bending strength of 106.26 MPa (FP) and 101.36 MPa (Y-FP) after sintering at 780 °C. This validated the materials as class 2 dental prosthetics citing ISO 6872:2015. Color gradation was verified by the yellow b* value reduction (14.8 to -3.33) as it shifted from cervical to incisal area while ΔE₀₀ further affirmed the differences from each segment in comparison with the FP and Y-FP.

SIGNIFICANCE

Color gradation was successfully replicated by FP and YAG:Ce composition shift via FGAM technique. This result highlights the potential of FGAM as an alternative for fabricating dental prosthetics with high efficiency and improved esthetic appeal.

Research Progress and Clinical Application of All-Ceramic Micro-Veneer

Anterior teeth problems affect the patient's daily eating, communication, social activities, self-confidence, and mental health. The trend in dentistry is to address anterior tooth problems with minimally invasive and aesthetic treatments. With the development of adhesive materials and ceramics, micro-veneers have been proposed as an alternative treatment for enhancing the aesthetic appearance and avoiding unnecessary tooth reduction. A micro-veneer is a veneer that can be cemented to the surface without or with minimal tooth preparation. These benefits include no need for anesthesia, postoperative insensitivity, good adhesion to enamel, reversibility of treatment, and higher patient acceptance. However, the micro-veneer repair is suitable only for specific cases and must be strictly controlled regarding indication. Treatment planning is a crucial step to achieving functional and aesthetic rehabilitation, and following the clinical protocol is helpful for the longevity and success of micro-veneer restorations. However, more precise and predictable tooth preparation methods, such as minimally invasive microscopic tooth preparation and digitally guided veneer preparation, are recommended rather than the traditional free-hand method. Therefore, this paper clarifies micro-veneers and compares them with other restorations to gain a deeper and more comprehensive understanding. The authors also review indications, materials, cementation, and effect evaluation of micro-veneers to provide clinicians with valuable information. In conclusion, micro-veneers are minimally invasive treatments that provide good restoration results when used appropriately and are worthy of promotion for the aesthetic restoration of anterior teeth.

An engineering perspective of ceramics applied in dental reconstructions

The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.

Influence of Cold Atmospheric Plasma on Surface Characteristics and Bond Strength of a Resin Nanoceramic

The purpose of this study was to investigate the effect of cold atmospheric plasma (CAP) treatment on resin nanoceramic (RNC) surface state and its bond strength with resin cement. RNC with different surface treatments were prepared: control, sandblasting treatment (SB), hydrofluoric acid etching (HF) and plasma treatment of helium gas (CAP-He) and argon gas (CAP-Ar). The prepared samples were measured by SEM, Ra, Rz, contact angle goniometer, and XPS for surface characteristics. The shear bond test of RNC was examined in nine groups: SB + saline coupling agent (SL), HF + SL, CAP-He/Ar, CAP-He/Ar + SL, SB + CAP-He/Ar + SL, and control. The bond strength between RNC and resin cement was compared using shear bond strength test, before and after thermocycling. After CAP irradiation, the surface topography maintained, while the surface water contact angle was significantly reduced to 10.18° ± 1.36° (CAP-He) and 7.58° ± 1.79° (CAP-Ar). The removal of carbon contamination and inducing of oxygen radicals was detected after CAP treatment. The bond strength was improved by CAP treatment, but varied on CAP gas species and combination methods. CAP of Ar gas had better SBS than He gas. After thermocycling, CAP-Ar + SL showed the maximized shear bond strength (32.38 ± 1.42 MPa), even higher than SB + SL group (30.08 ± 2.80 MPa, p < 0.05). In conclusion, CAP treatment of helium and argon can improve the bonding properties of RNC by improving surface wettability, and CAP of argon gas combined with silane coupling agent shows the highest bond strength.

Advances in Ceramics for Dental Applications

The purpose of this study is to present current dental ceramic materials and processing methods. The clinical indication was emphasized on basis of the material's microstructure and composition. Studies of ceramic characterization were also discussed, as they impact the clinical indication and serve as a parameter for the development of new materials. The novel strategies were mostly found aiming to mimic the natural dental structures, provide mechanical reliability, and develop predictable restorations in terms of adaptation and design.

TiO2 nanoparticles added to dense bovine hydroxyapatite bioceramics increase human osteoblast mineralization activity

OBJECTIVES

This study evaluated the effect of TiO₂ nanoparticles + dense hydroxyapatite (HA) on human osteoblast cells (SAOS-2).

METHODS

Particulate bovine HA powder with or without the addition of either 5 or 8 % TiO₂ (HA, HA/TiO₂Np5 % or HA/TiO₂Np8 %) were pressed into disks (Ø = 12.5 mm; thickness = 1.3 mm) uniaxially (100 MPa) and isostatically (200 MPa/1 min) and sintered at 1300 °C. Y-TZP disks were used as control. The following tests were performed: Scanning Electron Microscopy and Dispersive Energy Spectroscopy (SEM/EDS), Atomic Force Microscopy (AFM), cell viability assay (Alamar Blue-AB) and mineralized matrix deposition (Alizarin Red-AR). AB and AR data were submitted to 2-way ANOVA/Tukey tests and ANOVA/Tukey tests, respectively.

RESULTS

SEM revealed that the surface of HA/TiO₂Np5% resembles DPBHA surface, but also contains smaller granules. HA/TiO₂Np8% characteristics resembles HA/TiO₂Np5% surface, but with irregular topography. Y-TZP showed a typical oxide ceramic surface pattern. EDS revealed Ca, O, and P in all samples. C, O, and Zr appeared in Y-TZP samples. AFM data corroborates SEM analysis. AB test revealed excellent cellular viability for HA/TiO₂Np5% group. AR test showed that all groups containing TiO₂np had more mineralized matrix deposition than all other groups, with statistically differences between HA/TiO₂Np8% and HA cultivated in non-osteogenic medium. Culture in osteogenic medium exhibited much more mineralized matrix deposition by TiO₂np groups.

SIGNIFICANCE

In conclusion, the addition of TiO₂np showed chemical, superficial, and biological changes in the reinforced materials. HA/TiO₂Np5% showed the best results for cell viability and HA/TiO₂Np8% for mineralized matrix deposition.

Physical Properties and Color Stainability by Coffee and Red Wine of Opaque and High Translucency Zirconia Dental Ceramics after Hydrothermal Degradation

The objective was to evaluate the bending strength, phase transformation, roughness, and color stainability by coffee and red wine of opaque and high translucency yttria-stabilized zirconia before and after hydrothermal degradation in saline solution or oral mouthwash. Presintered zirconia blocks with medium opacity (ZrO₂-3 mol. % of Y₂O₃) designed as ZrOp and high translucency zirconia (5.2 mol. % of Y₂O₃) designed as ZrTrans were used. Specimens (n = 80/group) were cut and sintered at 1500°C for 2 h. The specimens were hydrothermally degraded in an autoclave (134°C–1.8 kg/cm²) for 20 h in saline solution (0.5 g/L) and oral mouthwash solution (0.02% sodium fluoride, without alcohol and with 21.6% alcohol). After hydrothermal degradation, the samples were immersed in containers with coffee or red wine for 14 days to determine their color stainability. The results showed that the ZrOp had a higher bending strength than the ZrTrans before and after hydrothermal aging. In ZrOp and ZrTrans, the roughness increased after hydrothermal degradation. ZrOp samples had a higher Ra roughness than the ZrTrans samples. Roughness did not change after immersion in coffee or red wine. The X-ray diffraction (XRD) results showed that ZrOp samples underwent a tetragonal to monoclinic phase transformation, while ZrTrans samples were unchanged. Both ZrOp and ZrTrans samples changed color after immersion in coffee and red wine.

Color stability of hybrid ceramics exposed to beverages in different combinations

Background

The aim of this study is to evaluate the color stability of hybrid ceramics stored in different combinations of beverages that are routinely consumed.

Methods

The specimens were prepared with resin nano-ceramic (Lava Ultimate, 3M Espe, USA) and hybrid ceramic (Vita Enamic, Vita Zahnfabrik, Germany). The specimens were aged in a thermocycler machine for 10,000 cycles. They were stored in different combinations of beverages (water, tea, coke, coffee, red wine, pomegranate juice, and turnip juice) for 12 + 12 h. Surface roughness measurements were performed using a profilometer. The specimen colors were measured using a spectrophotometer. The color values (L-a-b) of the specimens and mean surface roughness values (Ra) were recorded at the end of the 1st (D1), 7th (D7), 14th (D14) and 28th (D28) d.

Results

When the solution groups were examined, significant color changes were observed in the Lava coffee-tea, Enamic coffee-tea, Lava coffee-wine, and Enamic coffee-wine groups compared with the other groups (p < 0.01). Except for the samples in the Lava coffee-wine 28th day (D28) and Enamic coffee-wine 28th day (D28) groups, more color changes were observed in the Lava samples than in the Enamic samples across all groups and periods.

Conclusion

Greater color changes (except for the samples stored in coffee-wine) were observed in the Lava samples than in the Enamic samples across all groups and periods. It was observed that the coffee-tea and coffee-wine beverage combinations produced the greatest color change in hybrid ceramics within the limitations of this study.

Novel translucent monolithic zirconia fixed restorations in the esthetic zone

Novel translucent monolithic zirconia has improved optical properties, and it may fulfill patient's esthetic demands and overcome the chipping risk of bilayer metal-ceramic restorations. New zirconia's microstructures allow us to mimic natural teeth.

Saliva Influence on the Mechanical Properties of Advanced CAD/CAM Composites for Indirect Dental Restorations

This study aims to evaluate the microstructural and mechanical properties of three commercial resin-based materials available for computer-aid design and manufacturing (CAD/CAM)-processed indirect dental restoration: Lava^TM Ultimate Restorative (LU), 3M ESPE; Brilliant Crios (BC), COLTENE and Cerasmart^TM (CS), GC Dental Product. The three types of resin-based composite CAD/CAM materials were physically and mechanically tested under two conditions: directly as received by the manufacturer (AR) and after storage under immersion in artificial saliva (AS) for 30 days. A global approximation to microstructure and mechanical behaviour was evaluated: density, hardness and nanohardness, nanoelastic modulus, flexural strength, fracture toughness, fracture surfaces, and microstructures and fractography. Moreover, their structural and chemical composition using X-ray fluorescence analysis (XRF) and field emission scanning electron microscopy (FESEM) were investigated. As a result, LU exhibited slightly higher mechanical properties, while the decrease of its mechanical performance after immersion in AS was doubled compared to BC and CS. Tests of pristine material showed 13 GPa elastic modulus, 150 MPa flexural strength, 1.0 MPa·m^1/2 fracture toughness, and 1.0 GPa hardness for LU, 11.4 GPa elastic modulus; 140 MPa flexural strength, 1.1 MPa·m^1/2 fracture toughness, and 0.8 GPa hardness for BC; and 8.3 GPa elastic modulus, 140 MPa flexural strength, 0.9 MPa·m^1/2 fracture toughness, and 0.7 GPa hardness for CS. These values were significantly reduced after one month of immersion in saliva. The interpretation of the mechanical results could suggest, in general, a better behaviour of LU compared with the other two despite it having the coarsest microstructure of the three studied materials. The saliva effect in the three materials was critically relevant for clinical use and must be considered when choosing the best solution for the restoration to be used.