Failure and complication rates of different materials, designs, and bonding techniques of ceramic cantilever resin-bonded fixed dental prostheses for restoring missing anterior teeth: A systematic review and meta-analysis

OBJECTIVES

The objective of this review was to assess clinical trials that have examined the materials, design, and bonding of ceramic cantilevered resin-bonded fixed dental prostheses (RBFDPs) as a potential option for replacing missing anterior teeth. The evaluation primarily focuses on the rate of restoration failure and clinical complications.

MATERIALS AND METHODS

A thorough search of databases including PubMed/MEDLINE, Scopus, and the Cochrane Library, was conducted. The most recent search was performed in October 2023. Clinical studies that compared ceramic cantilevered RBFDPs with double retainers or cantilevered RBFDPs using different ceramic materials or bonding systems were included. The outcome measures considered were restoration failure and complication rates.

RESULTS

Twelve studies met the eligibility criteria. The pooled data showed a statistically significant decrease in complication events when using cantilever designs compared with double retainer designs (p < 0.05); however, there were no differences found between the two designs in terms of restoration failure. The complication and failure rate of cantilever RBFDPs did not show a statistically significant difference with or without ceramic primer application before luting with phosphate monomer-containing luting resin (p > 0.05).

CONCLUSIONS

Ceramic cantilevered RBFDPs have lower complication rates compared with those with double retainers. The use of a ceramic primer prior to luting composite resin for ceramic cantilevered RBFDPs decreases the occurrence of complications and failures, although this effect was not statistically significant. Additional research is required to confirm these findings. Glass ceramic cantilever RBFDPs showed a decrease in success after 6 years, requiring ongoing monitoring, but both zirconia and glass-infiltrated alumina cantilever RBFDPs have demonstrated durability with excellent long-term success and survival rates for up to 10 and 15 years.

CLINICAL SIGNIFICANCE

Cantilever ceramic RBFDPs in the anterior region are a less invasive and valuable treatment option, providing good esthetic results.

Influence of retainer design and number of inlay boxes on the biomechanical behavior of zirconia cantilever resin bonded fixed dental prosthesis

OBJECTIVES

The development of dental adhesives with enhanced bond strength has assisted minimally invasive dentistry. The aim of this study was to evaluate the fracture load and stress distribution pattern of two retainer designs for posterior cantilever resin bonded fixed dental protheses (RBFDPs).

MATERIALS AND METHODS

Forty human mandibular molars were divided into two groups according to the retainer design; lingual coverage (LC) and occlusal coverage (OC) retainers. Each main group was then divided according to the number of inlay boxes (n = 10); one inlay and two inlay boxes. High translucency (3Y) zirconia was used to manufacture all restorations, and a dual-polymerizing adhesive resin cement was used for bonding. All specimens underwent 10,000 cycles of thermocycling (5-55°C), 240,000 cycles of dynamic loading (50 N, descending speed v = 30 mm/second, frequency = 1.6 Hz), and failure load test. Both one-way and two-way ANOVA tests were used to analyze the data. The four models included in the in-vitro study are part of the finite element analysis (FEA). When the restorations failed, maximal principal stress values on restorations, enamel, dentin, and luting resin were investigated.

RESULTS

A statistically significant (p = 0.018) higher failure load was recorded for OC1 (627.00 ± 153.4 N) than the other groups; (548.0 ± 75.6 N, 521.20 ± 11.3 N, and 509.20 ± 14.9 N for LC1, LC2, and OC2, respectively). With regard to failure mode, one inlay box designs showed more favorable failure pattern than those of two inlay boxes. FEA showed higher stress magnitude transmitted to the tooth structure in models LC2 and OC2.

CONCLUSIONS

Lingual coverage and occlusal coverage retainers are promising designs capable to withstand the normal occlusal force for cantilever RBFDP in premolar area. The use of two inlay boxes decreased the fracture load of the two retainer designs and increased the stress transmitted to the tooth and resulted in high incidence of catastrophic failure.

CLINICAL SIGNIFICANCE

Monolithic high translucent zirconia RBFDP could be considered as a viable treatment option to substitute missing posterior tooth, with improved esthetics and biocompatibility.

Retention of titanium copings to implant-supported fixed dental prostheses

PURPOSE

The aim of this in vitro study was to assess the effects of using different cements and titanium copings designs on the retention of implant-supported fixed dental prostheses (IFDPs) using a pull-out test.

MATERIALS AND METHODS

Fifty zirconia (ZirCAD; Ivoclar Vivadent) and 20 prepolymerized denture acrylic resin (AvaDent) rectangular (36 mm × 12 mm × 8 mm) specimens were milled to mimic the lower left segmental portion of the All-on-Four IFDPs. Cylindrical titanium copings (Variobase; Straumann) (V) were used in 2 prepolymerized denture acrylic resin groups (n = 10) while conical titanium copings (Straumann) (C) were used as a control group for zirconia with 4 groups using cylindrical titanium copings. Before cementation, the outer surfaces of all titanium copings and the intaglio bonding surface of prosthetic specimens were airborne-particle abraded. All specimens were cemented following the manufacturer's recommendations and instructions according to the experimental design. After artificial aging (5000 cycles of 5°C 55°C, dwelling time 20 s; 150 N, 1.5 Hz in a 37°C water bath), all specimens were subjected to retention force testing using a pull-out test using a universal testing machine and a custom fixture with a crosshead speed 5 mm/min. Modes of failure were classified as Type 1, 2, or 3. Retention force values were analyzed by the t-test for the prepolymerized denture acrylic resin specimen groups, and 1-way ANOVA and the Tukey test for the zirconia groups at α = 0.05.

RESULTS

Mean and standard deviation retention force values varied from 101.1 ± 67.1 to 509.0 ± 65.2 N for the prepolymerized denture acrylic resin specimen groups. The zirconia groups ranged from 572.8 ± 274.7 to 1416.1 ± 258.0 N. There is no statistically significant difference in retention force values between V and C specimens cementing to zirconia with Panavia SA cement (Kuraray Noritake) (p = 0.587). The retention forces and failure modes were influenced by the cement used (p < 0.05). Modes of failure were predominantly Type 2 (mixed failure) and Type 1 (adhesive fracture from prosthetic materials) except for the quick-set resin group (Type 3, adhesive failure from coping).

CONCLUSIONS

When bonding IFDPs onto titanium copings, quick-set resin provided significantly higher retention force for prepolymerized denture acrylic resin prostheses. Conical and cylindrical titanium copings performed similarly when cemented to zirconia with Panavia SA cement under the same protocol. The stability of the bonded interface and retention forces between zirconia prostheses and titanium copings varied from the cement used.

Stress distribution on implant- supported zirconia crown of maxillary first molar: effect of oblique load on natural and antagonist tooth

This study evaluated the stress distribution on an implant-supported zirconia crown of a mandibular first molar subjected to oblique loading by occlusal contact with the natural maxillary first molar by using the 3D finite element method. Two virtual models were made to simulate the following situations: (1) occlusion between maxillary and mandibular natural first molars; (2) occlusion between zirconia implant-supported ceramic crown on a mandibular first molar and maxillary natural first molar. The models were designed virtually in a modeling program or CAD (Computer Aided Design) (Rhinoceros). An oblique load of 100 N was uniformly applied to the zirconia framework of the crown. The results were obtained by the Von Mises criterion of stress distribution. Replacement of the mandibular tooth by an implant caused a slight increase in stress on portions of the maxillary tooth roots. The crown of the maxillary model in occlusion with natural antagonist tooth showed 12% less stress when compared with the maxillary (model in occlusion with the) implant-supported crown. The mandibular crown of the implant show 35% more stress when compared with the mandibular antagonist crown on the natural tooth. The presence of the implant to replace the mandibular tooth increased the stresses on the maxillary tooth, especially in the region of the mesial and distal buccal roots.

Effect of toothbrushing on surface roughness, gloss, and topography of polished and glazed ultra-translucent zirconia

PURPOSE

This study evaluated the effect of toothbrushing cycles on surface roughness (Ra), gloss (GU), and morphology of two zirconia finishing and polishing protocols.

MATERIALS AND METHODS

An ultra-translucent zirconia disc was sectioned into rectangular plates (12 mm × 7 mm × 3 mm) and divided into two groups according to the polishing and finishing system used (diamond rubber abrasive/DRA or glazing/GLA). Bovine enamel (BEN) plates with the same dimensions were used as a Control. Specimens of zirconia and enamel were analyzed for Ra and GU (n = 11) and surface morphology by scanning electron microscopy (n = 3) before toothbrushing (baseline) and after 15,000 and 30,000 toothbrushing cycles. Ra and GU data were analyzed by ANOVA two-way and post-hoc Tukey's test (α = 0.05), while the surface morphology was analyzed qualitatively.

RESULTS

The Ra decreased significantly after 30,000 toothbrushing cycles for DRA and GLA zirconia ceramics. DRA showed a higher GU at the baseline, after 15,000 and 30,000 toothbrushing cycles than GLA and BEN. Toothbrushing polished the zirconia, creating a smooth surface, while no changes were observed for BEN.

CONCLUSIONS

The increase in toothbrushing cycles (30,000) changed the surface roughness of DRA and GLA zirconia ceramics. DRA zirconia presented the highest GU, which did not change with toothbrushing.

Comparing Zirconium Crown Marginal Adaptation in Preparations with Two Different Occlusal Reductions

This study aimed to assess and contrast the effects on the vertical marginal fit of full contour CAD/CAM-generated monolithic zirconia crowns at pre- and post-cementation levels with various occlusal reduction schemes (planar and flat) and cements. Forty sound human maxillary first premolars were sampled for this study. The samples were divided into two main groups with twenty samples in each group according to the occlusal reduction scheme as follows: Group A included a chamfer finishing line design with a planar occlusal reduction scheme and Group B included a chamfer finishing line design with a flat occlusal reduction scheme. Each group was sampled into two subgroups (n = 10) based on the type of cement as follows: resin-modified glass ionomer cement (Fuji Plus) for subgroups A1 and B1, and a universal adhesive system (Duo Estecem II) for subgroups A2 and B2. Marginal gaps were tested in four indentations using a Dino light stereomicroscope (230×). Paired T-tests and Student's t-tests were used to analyze the data. Before cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, while subgroup B2 scored the highest mean; following cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, and subgroup B2 scored the highest mean of vertical marginal gap values. A chamfer finishing line design with a planar occlusal reduction scheme could be a preferable occlusal reduction scheme.

Cell Biological and Antibacterial Evaluation of a New Approach to Zirconia Implant Surfaces Modified with MTA

Peri-implantitis continues to be one of the major reasons for implant failure. We propose a new approach to the incorporation of MTA into zirconia implant surfaces with Nd:YAG laser and investigate the biological and the microbiological responses of peri-implant cells. Discs of zirconia stabilized with yttria and titanium were produced according to the following four study groups: Nd:YAG laser-textured zirconia coated with MTA (Zr MTA), Nd:YAG laser-textured zirconia (Zr textured), polished zirconia discs, and polished titanium discs (Zr and Ti). Surface roughness was evaluated by contact profilometry. Human osteoblasts (hFOB), gingival fibroblasts (HGF hTERT) and S. oralis were cultured on discs. Cell adhesion and morphology, cell differentiation markers and bacterial growth were evaluated. Zr textured roughness was significantly higher than all other groups. SEM images reveal cellular adhesion at 1 day in all samples in both cell lines. Osteoblasts viability was lower in the Zr MTA group, unlike fibroblasts viability, which was shown to be higher in the Zr MTA group compared with the Zr textured group at 3 and 7 days. Osteocalcin and IL-8 secretion by osteoblasts were higher in Zr MTA. The Zr textured group showed higher IL-8 values released by fibroblasts. No differences in S. oralis CFUs were observed between groups. The present study suggests that zirconia implant surfaces coated with MTA induced fibroblast proliferation and osteoblast differentiation; however, they did not present antibacterial properties.

Enhanced Mechanical and Electromechanical Properties of Compositionally Complex Zirconia Zr1-x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2-δ Ceramics

Compositionally complex oxides (CCOs) or high-entropy oxides (HEOs) are new multielement oxides with unexplored physical and functional properties. In this work, we report fluorite structure-derived compositionally complex zirconia with composition Zr1-x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2-δ (x = 0.1 and 0.2) synthesized in solid-state reaction route and sintered via hot pressing at 1350 °C. We explore the evolution of these oxides' structural, microstructural, mechanical, electrical, and electromechanical properties regarding phase separation and sintering mechanisms. Highly dense ceramics are achieved by bimodal mass diffusion, composing nanometric tetragonal and micrometric cubic grains microstructure. The material exhibits an anomalously large electrostriction response exceeding the M33 value of 10-17 m2/V2 at room temperature and viscoelastic properties of primary creep in nanoindentation measurement under fast loading. These findings are strikingly similar to those reported for doped ceria and bismuth oxide derivates, highlighting the presence of a large concentration of point defects linked to structural distortion and anelastic behavior, which are characteristics of nonclassical ionic electrostrictors.

Optical properties of dental zirconia, bovine dentin, and enamel-dentin structures

OBJECTIVE

To evaluate the optical properties and the relative translucency parameter of Ceramill ZI White (3Y-TZP) and Ceramill Zolid FX White (5Y-PSZ) zirconia ceramic systems and compare them with those of the bovine dentin and enamel/dentin structures.

MATERIALS AND METHODS

3Y-TZP and 5Y-PSZ zirconia ceramic systems were evaluated. A 0.5-mm-thick 3Y-TZP (3Y-NC.5), 0.5-mm-thick (5Y-NC.5), and 1.4-mm-thick (5Y-C.14) were used. A 0.5-mm-thick dentin specimens and 1.4-mm-thick enamel/dentin specimens (n = 5) were obtained from anterior bovine maxillary teeth. Scattering, absorption, transmittance, and albedo coefficient were calculated using Kubelka-Munk's model. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (p < 0.001), and goodness-of-fit coefficient (GFC). Relative translucency parameter differences were evaluated using translucency thresholds.

RESULTS

Reflectance, scattering, absorption, and transmittance properties were wavelength dependent. Good matches (GFC ≥ 0.999) in spectral reflectance were observed between 0.5-mm-thick dentin and 1.4-mm-thick enamel/dentin, and 3Y-NC.5 and 5Y-NC.5. Scattering was the main optical extinction process during light interaction with zirconia and dental structures, as indicated by albedo coefficient. Translucency differences were acceptable only for 3Y-NC.5 and the dentin structure, and 5Y-C.14 and the enamel/dentin structure.

CONCLUSIONS

Optical properties of 3Y-TZP and 5Y-PSZ dental zirconia differed from each other and from bovine dental structures. Nevertheless, 3Y-TZP showed similar relative translucency parameter to bovine dentin.

CLINICAL SIGNIFICANCE

To achieve the best esthetic results in restorative dentistry, it is crucial for clinicians to know about the optical properties of 3Y-TZP and 5Y-PSZ and to be able to compare these properties with those of dental structures.

An in vitro study

PURPOSE

Investigate survival and technical complications of two-unit posterior implant-supported cantilever made of monolithic zirconia on titanium-base abutments (Zr-TiB) vs. porcelain-fused-to-metal on castable gold abutments (PFM-GA) using two different implant connections, internal butt-joint (IBJ) and internal conical (IC).

MATERIALS AND METHODS

Forty-eight implants (4.3 mm diameter) were divided into four groups (n = 12) to support 2-unit mandibular premolar cantilevers with two different materials (Zr-TiB vs. PFM-GA) and two connection types (IBJ vs. IC). Tested groups were as follows: (1) IBJ/Zr-TiB; (2) IBJ/PFM-GA; (3) IC/Zr-TiB; and (4) IC/PFM-GA. Specimens were thermomechanical aged (1,200,000 cycles, 98 N, 5-55°C) with occlusal axial load on the pontic. Catastrophic and non-catastrophic events were registered, and removal torque values measured before and after aging. Specimens surviving aging were subjected to loading until failure. Survival, total complication rates, torque loss (%), and bending moments were calculated.

RESULTS

From 48 specimens, 38 survived aging. Survival rates significantly varied from 16.7% (IC/PFM-GA) to 100% (IBJ/Zr-TiB; IBJ/PFM-GA; IC/Zr-TiB) (p < .01). Internal conical connection revealed significantly higher torque loss (IC/ZrTiB - 67%) compared to internal butt-joint (IBJ/Zr-TiB - 44%; IBJ/PFM-GA - 46%) (p < .01). Bending moments were higher in internal butt-joint connections than in internal conical (p < .05).

CONCLUSION AND CLINICAL IMPLICATIONS

Two-unit posterior implant-supported cantilever FDPs replacing mandibular premolars composed of monolithic zirconia on titanium-base abutments demonstrated higher mechanical stability compared to porcelain-fused-to-metal on castable gold abutments in this in vitro study. The internal conical connection combined with porcelain-fused-to-metal on gold abutments revealed a high number of failures; therefore, their clinical use may be considered cautiously for this indication.

The Effect of Die Material on the Crown Fracture Strength of Zirconia Crowns

BACKGROUND

Determination of the eligibility of several tooth analog materials for use in crown fracture testing.

METHODS

A standardized premolar crown preparation was replicated into three types of resin dies (C&B, low modulus 3D printed resin; OnX, high modulus 3D printed resin composite; and highest modulus milled resin composite). 0.8 mm zirconia crowns were bonded to the dies and the maximum fracture load of the crowns was tested. Twelve extracted human premolars were prepared to a standardized crown preparation, and duplicate dies of the prepared teeth were 3D printed out of C&B. Zirconia crowns were bonded to both the dies and natural teeth, and their fracture load was tested.

RESULTS

There was no statistical difference between the fracture load of zirconia crowns bonded to standardized dies of C&B (1084.5 ± 134.2 N), OnX (1112.7 ± 109.8 N) or Lava Ultimate (1137.5 ± 88.7 N) (p = 0.580). There was no statistical difference between the fracture load of crowns bonded to dentin dies (1313 ± 240 N) and a 3D-printed resin die (C&B, 1156 ± 163 N) (p = 0.618).

CONCLUSIONS

There was no difference in the static fracture load of zirconia crowns bonded to standardized resin dies with different moduli or between a low modulus resin die and natural dentin die.

Materials and Methods for All-Ceramic Dental Restorations Using Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) Technologies-A Brief Review

The materials used in dentistry for the fabrication of all-ceramic restorations have undergone great and rapid developments over the last two decades. Among the most common ceramic materials in dentistry are those based on zirconium and lithium disilicate. Due to the properties of these materials, they are in great demand in the field of dental restoration production. Thus, dental restorations that will use those materials are commonly machined in CAD/CAM systems, which offer the possibility of manufacturing all-ceramic dental restorations in a very short period of time. This article reviews the modern materials in the field of all-ceramic dental restorations, their manufacturing processes, as well as what determines which ceramic materials are used for the production of CAD/CAM blanks and their production technology.

Reversible and Irreversible Structural Changes in Cu/ZnO/ZrO2 Catalysts during Methanol Synthesis

The structure and chemical state of heterogeneous catalysts are closely related to their operational stability. Knowing these relationships as precisely as possible is thus essential for further catalyst development. This work focuses on the deactivation of a Cu/ZnO/ZrO2-type catalyst for methanol synthesis. Experiments were performed in a parallel setup, with which time-dependent changes in the catalyst material can be observed. Elucidation of potential deactivation pathways is described for catalyst aging at different times on stream (0, 50, 935 h). Data from X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, N2 physisorption, and transmission electron microscopy measurements reveal that sintering of Cu0 domains and restructuring within ZnO domains mainly contribute to deactivation. Subsequent reactivation by reduction (in H2/N2) reverts the observed structural changes only to a limited extent. Moreover, this work highlights the participation of ZrO2 as a promoter and reveals redispersion of zirconia after initial reduction.

Zirconia Hybrid Dental Implants Influence the Biological Properties of Neural Crest-Derived Mesenchymal Stromal Cells

Dental implants are regularly employed in tooth replacement, the good clinical outcome of which is strictly correlated to the choice of an appropriate implant biomaterial. Titanium-based implants are considered the gold standard for rehabilitation of edentulous spaces. However, the insurgence of allergic reactions, cellular sensitization and low integration with dental and gingival tissues lead to poor osseointegration, affecting the implant stability in the bone and favoring infections and inflammatory processes in the peri-implant space. These failures pave the way to develop and improve new biocompatible implant materials. CERID dental implants are made of a titanium core embedded in a zirconium dioxide ceramic layer, ensuring absence of corrosion, a higher biological compatibility and a better bone deposition compared to titanium ones. We investigated hDPSCs' biological behavior, i.e., cell adhesion, proliferation, morphology and osteogenic potential, when seeded on both CERID and titanium implants, before and after cleansing with two different procedures. SEM and AFM analysis of the surfaces showed that while CERID disks were not significantly affected by the cleansing system, titanium ones exhibited well-visible modifications after brush treatment, altering cell morphology. The proliferation rate of DPSCs was increased for titanium, while it remained unaltered for CERID. Both materials hold an intrinsic potential to promote osteogenic commitment of neuro-ectomesenchymal stromal cells. Interestingly, the CERID surface mitigated the immune response by inducing an upregulation of anti-inflammatory cytokine IL-10 on activated PBMCs when a pro-inflammatory microenvironment was established. Our in vitro results pave the way to further investigations aiming to corroborate the potential of CERID implants as suitable biomaterials for dental implant applications.

Effect of Different Primers on Shear Bond Strength of Base Metal Alloys and Zirconia Frameworks

Ensuring a secure bond between a framework structure and layering composite resin veneer is essential for a long-lasting dental restoration. A variety of primer systems are available to facilitate the adhesive bonding. Nevertheless, the growing preference for efficiency and simplicity in dentistry has made the one-bottle universal primers a desirable option. This study aims to compare the effectiveness of universal primers on the shear bond strength (SBS) of base metal alloy (BMA) and zirconia to layering composite resin. Each 160 BMA and zirconia 20 × 10 × 5 mm test specimen was fabricated. Eight different primers (SunCera Metal Primer, Metal Primer Z, Reliance Metal Primer, Alloy Primer, MKZ Primer, Monobond Plus, ArtPrime Plus, and Clearfil Ceramic Primer Plus) were applied to 20 specimens in each group. Subsequently, a 5 × 2 mm composite resin build-up was applied. SBS tests were performed after 24 h of water storage and after thermocycling (25,000 cycles, 5-55 °C). On BMA, after water storage for 24 h, the bond strength values ranged from 26.53 ± 3.28 MPa (Metal Primer Z) to 29.72 ± 2.00 MPa (MKZ Primer), while after thermocycling, bond strength values ranged from 25.19 ± 1.73 MPa (MKZ Primer) to 27.69 ± 2.37 MPa (Clearfil Ceramic Primer Plus). On a zirconia base, after 24 h, the bond strengths values ranged from 22.63 ± 2.28 MPa (Reliance Primer) to 29.96 ± 2.37 MPa (MKZ Primer) and from 23.77 ± 3.86 MPa (Metal Primer Z) to 28.88 ± 3.09 MPa (Monobond Plus) after thermocycling. While no significant difference in bond strength was found between the primers on the BMA base, five primer combinations differed significantly from each other on zirconia (p = 0.002-0.043). All primers achieved a bond strength greater than 23 MPa on both framework materials after thermocycling. Thus, all primers tested can be applied to both framework materials with comparable results.

Wettability of Different Zirconia Implant Surfaces after Glycine and Erythritol Treatment

PURPOSE

This in-vitro study aims to investigate whether the wettability of two zirconia implant disk surfaces is affected by glycine and erythritol air-polishing, using saline, bovine serum albumin, bovine thrombin, and bovine artificial blood as the testing mediums.

MATERIALS AND METHODS

Zirconia disks were provided by two implant companies: SDS. (Swiss Dental Solutions, Plymouth, MA, USA) (n=6) and Patent. (Zircon Medical AG, Altendorf, Switzerland) (n=6). Surface parameters (Sa, Sz, Sdr, Ssk, Sku, and Spd) were measured to determine their initial surface roughness. Air-polishing was completed using glycine or erythritol powders using the AIRFLOW. PERIO device (Manufactured by Electro Medical Systems (EMS)). The wettability of the disk surfaces was evaluated by the contact angle analysis applied on treated and untreated disks using four wetting solutions, saline, bovine serum albumin (BSA), bovine thrombin, and bovine artificial blood. In total, 720 contact angle measurements were completed with n=30 per group. Statistical analysis was performed using the one-way analysis of variance and post-hoc Tukey HSD test.

RESULTS

The results indicate SDS. has a greater wettability than Patent. before and after air-polishing. The wettability of surfaces treated with glycine was hydrophobic in some cases. Erythritol increased the surface wettability of zirconia disks compared to glycine. BSA and bovine artificial blood had lower contact angles than saline and bovine thrombin for both untreated disks.

CONCLUSIONS

The initial wettability of zirconia disks differs between manufacturers, and air-polishing with erythritol powder increases the wettability of zirconia implant disks for saline, bovine serum, bovine thrombin, and bovine artificial blood.

Effect of Zirconia Thickness, Cement Color, and Titanium Implant Abutment Surface Treatment Type on the Esthetic Outcomes of High Translucency Monolithic Zirconia

PURPOSE

To investigate the esthetic outcomes based on the color differences in zirconia of varying thickness, resin cement color, and types of titanium implant surface treatments.

MATERIALS AND METHODS

Twenty-eight HTMZ specimens were arranged into four groups based on zirconia thickness: 1.0, 1.5, 2.0, and 2.5 mm (n=7). Each group was tested using two resin cement colors (n=7) (clear and opaque) in combination with six surface-treated titanium groups (n=7): untreated titanium (UT), anodization (AN), 50-μm alumina airborne-particle abrasion followed by AN (SBAN), AN followed by 50-μm alumina airborne-particle abrasion (ANSB), 95% hydrofluoric acid followed by AN (HFAN), and AN followed by 95% hydrofluoric acid (ANHF) for the 48 experimental groups, and using composite resin (n=7) (A2D) for the four control groups. All the specimens were measured using a spectrophotometer and subsequently compared with composite resin (control) with the corresponding zirconia thickness to establish the color differences. A color difference of <2.7 was considered clinically acceptable. The data obtained were statistically analyzed using the analysis of variance and post hoc test (p=0.05).

RESULTS

Zirconia thickness, resin cement color, and type of titanium implant surface treatment significantly affected the observed color differences (p<0.05). When using 2.5-mm HTMZ with clear resin cement on AN, UT, SBAN, HFAN, and ANSB, the mean color differences obtained were below the clinically acceptable values. However, when using 2.5-mm HTMZ with clear resin cement on AN, UT, and SBAN, the 95% confidence intervals of color differences obtained were below the clinically acceptable values.

CONCLUSIONS

HTMZ with a minimum thickness of 2.5 mm and clear resin cement on AN, UT, and SBAN groups potentially result in acceptable color matching with 95% confidence intervals.

Femtosecond Laser Irradiation to Zirconia Prior to Calcium Phosphate Coating Enhances Osteointegration of Zirconia in Rabbits

Calcium phosphate (CaP) coating of zirconia and zirconia-based implants is challenging, due to their chemical instability and susceptibility to thermal and mechanical impacts. A 3 mol% yttrium-stabilized tetragonal zirconia polycrystal was subjected to femtosecond laser (FsL) irradiation to form micro- and submicron surface architectures, prior to CaP coating using pulsed laser deposition (PLD) and low-temperature solution processing. Untreated zirconia, CaP-coated zirconia, and FsL-irradiated and CaP-coated zirconia were implanted in proximal tibial metaphyses of male Japanese white rabbits for four weeks. Radiographical analysis, push-out test, alizarin red staining, and histomorphometric analysis demonstrated a much improved bone-bonding ability of FsL-irradiated and CaP-coated zirconia over CaP-coated zirconia without FsL irradiation and untreated zirconia. The failure strength of the FsL-irradiated and CaP-coated zirconia in the push-out test was 6.2-13.1-times higher than that of the CaP-coated zirconia without FsL irradiation and untreated zirconia. Moreover, the adhesion strength between the bone and FsL-irradiated and CaP-coated zirconia was as high as that inducing host bone fracture in the push-out tests. The increased bone-bonding ability was attributed to the micro-/submicron surface architectures that enhanced osteoblastic differentiation and mechanical interlocking, leading to improved osteointegration. FsL irradiation followed by CaP coating could be useful for improving the osteointegration of cement-less zirconia-based joints and zirconia dental implants.

3Y-TZP/Ta Biocermet as a Dental Material: An Analysis of the In Vitro Adherence of Streptococcus Oralis Biofilm and an In Vivo Pilot Study in Dogs

The surface adhesion of bacterial cells and the in vivo biocompatibility of a new ceramic-metal composite made of zirconium dioxide and tantalum were evaluated. Within the framework of an in vitro study using the crystal violet staining and colony counting methods, a relatively similar adhesion of Streptococcus oralis to the 3Y-TZP/Ta biocermet (roughness Ra = 0.12 ± 0.04 µm) and Ti-Al6-V4 titanium alloy (Ra = 0.04 ± 0.01 µm) was found. In addition, in an in vivo preliminary study focused on the histological analysis of a series of rods implanted in the jaws of beagle dogs for a six-month period, the absence of any fibrous tissue or inflammatory reaction at the interface between the implanted 3Y-TZP/Ta biocermets and the new bone was found. Thus, it can be concluded that the developed ceramic-metal biocomposite may be a promising new material for use in dentistry.

Wear of lithium disilicate opposed by various ceramic materials

OBJECTIVES

To compare volumetric wear of lithium disilicate against different ceramic (3 mol% yttria-stabilized (3Y) zirconia, 5 mol% yttria-stabilized (5Y) zirconia, lithium disilicate, porcelain and enamel antagonists).

MATERIALS AND METHODS

Forty lithium disilicate (e.max CAD) specimens (n = 8/antagonist) were wet sanded to 1200grit SiC and mounted into a UAB wear device. Antagonist spheres (diameter = 4.75 mm) were made from polished 3Y zirconia, 5Y zirconia, lithium disilicate, porcelain and human enamel. A two-body wear test was performed with 20 N load and 1.5 mm slide for 400,000 cycles at 1 Hz. 33% glycerin was used as a lubricant. Wear facets were measured with optical profilometry. Wear scar areas of antagonists were measured with digital microscopy. Scanning electron microscopy was performed on wear facets and scars. Vicker's microhardness was measured of all antagonist materials. All data were compared with 1-way ANOVA and Tukey post-hoc analysis.

RESULTS

Significant differences in lithium disilicate volumetric wear (mm3 ) occurred with various antagonist materials: 0.38 ± 0.01a (3Y zirconia), 0.33 ± 0.01b, (5Y zirconia), 0.16 ± 0.01c (lithium disilicate), 0.11 ± 0.03d, (enamel), and 0.07 ± 0.01e (porcelain). The lithium disilicate antagonist demonstrated a larger wear scar than other materials. Zirconia was the hardest material and enamel the least hard.

CONCLUSIONS

Zirconia causes significant wear on lithium disilicate and lithium disilicate causes significant wear against itself.

CLINICAL SIGNIFICANCE

When selecting a material to oppose an existing lithium disilicate crown, a porcelain or lithium disilicate surface would cause significantly less wear to the existing crown. If an existing zirconia crown exists opposed to a prepared tooth, lithium disilicate may not be an ideal material selection to restore the tooth.

Development, characterization, and biological study of bioglass coatings 45S5 and BioK on zirconia implant surfaces

Zirconia implants are gaining attention as a viable alternative to titanium implants due to their comparable osseointegration development, improved soft tissue adaptation, and enhanced aesthetics. An encouraging avenue for improving zirconia implant properties involves the potential application of bioactive coatings to their surfaces. These coatings have shown potential for inducing hydroxyapatite formation, crucial for bone proliferation, and improving implant mechanical properties. This study aimed to evaluate the effect of coating zirconia implants with two bioactive glasses, 45S5 and BioK, on osteogenesis in vitro and osseointegration in vivo. Zirconia samples and implants were prepared using Zpex zirconia powder and blocks, respectively. The samples were divided into three groups: polished zirconia (ZRC), zirconia coated with 45S5 bioglass (Z + 45S5), and zirconia coated with BioK glass (Z + BK). Coatings were applied using a brush and sintered at 1200°C. Chemical analysis of the coatings was carried out using x-ray diffraction and Fourier Transform Infrared Spectroscopy. Surface topography and roughness were characterized using scanning electron microscopy and a roughness meter. In vitro experiments used mesenchymal cells from Wistar rat femurs, and the coated zirconia implants were found to promote cell viability, protein synthesis, alkaline phosphatase activity, and mineralization, indicating enhanced osteogenesis. In vivo experiments with 18 rats showed positive results for bone formation and osseointegration through histological and histomorphometric analysis and a push-out test. The findings indicate that bioactive glass coatings have the potential to improve cell differentiation, bone formation, and osseointegration in zirconia implants.

Worn denture teeth of a full-arch implant-supported fixed dental prosthesis: A technique to restore

Worn denture teeth continue to be a significant complication with implant-supported prostheses. This article discusses a case report that used an intraoral scanning system to restore an existing maxillary implant-supported prosthesis with significant posterior occlusal wear.  IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) restorations were fabricated and cemented to the prepared posterior denture teeth to re-establish the occlusal vertical dimension and to help prevent further wear of the occlusal surfaces.

Functionalization of a zirconia surface by covalently immobilized fibronectin and its effects on resistance to thermal, acid, and mechanical exposure

Silane chemistry has emerged as a powerful tool for surface modification, offering a versatile means to enhance the properties of various substrates, such as dental implant abutment materials. In this study, we investigated the stability of the 3-aminopropyldiisopropylethoxysilane (APDS) layer on yttria-partially stabilized zirconia (Y-TZP) surfaces after mechanical, acid, and thermal treatment in order to simulate fluctuations within the oral cavity. To accomplish that, the viability of human gingival fibroblasts on APDS-modified surfaces after applied treatment strategies was assessed by live/dead staining. Moreover, the hydrolysis stability and enzymatic degradation resistance of crosslinked fibronectin to the APDS layer was examined by immunostaining and western blot. The results revealed that the applied modifications were not affected by the different treatment conditions and could withstand the fluctuations in the oral cavity. Furthermore, crosslinked fibronectin on silanized Y-TZP was stable against hydrolysis over 21 days and enzymatic degradation. We thus can conclude that the proposed functionalization method has high potential to tolerate harmful effects within the oral cavity and remains unchanged on the surface.

Comparison of bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia: A systematic review and meta-analysis

The aim of this study was to systematically compare the bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia. The PubMed, ISI (all), and Scopus databases were searched for the selected keywords up to November 1, 2021, without date or language restrictions. In vitro studies comparing the bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia were eligible for inclusion in the study. The selected articles were divided into four groups based on the type of resin cement and the storage time. Statistical analysis was performed using the Biostat Comprehensive Meta-Analysis Software version 2 (α = 0.05). The effect of conventional cement ( Glass Ionomer (GI), Resin Modified Glass Ionomer (RMGI) and zinc phosphate) was analyzed using descriptive analysis. The initial search yielded 376 articles, of which 26 were selected after a methodological assessment. Two reviewers independently extracted data and assessed the risk of bias. The results showed that the immediate or delay bond strength of the self-adhesive resin cement to zirconia has no significant difference with the bond strength of self-etch resin cement to zirconia. The immediate and delay bond strength of total-etch cement-zirconia was significantly lower than that of self-adhesive cement-zirconia (P = 0.00). A descriptive analysis of the selected articles showed that the bond strength of self-adhesive resin cement to zirconia was significantly higher than total-etch cement. The results of the meta-analysis showed that both self-adhesive and self-etch resin cement (if applied according to their manufacturer's instruction) are suitable for bonding to zirconia.

Endocrown Feasibility for Primary Molars: A Finite Element Study

OBJECTIVE

 To study the possibility of using pediatric endocrowns to restore the second primary molar using three-dimensional (3D) finite element analysis.

DESIGN

 A 3D finite element model was built for a pediatric mandibular molar, starting with laser scanning a naturally extracted tooth. The access cavity had an elliptic shape with 6 mm width, 4 mm height, and 2 mm depth with a wall taper angle of 5 degrees.Two materials (Zr and E-max) were tested for the endocrown and two cementing materials (glass ionomer and resin cement) with 20 to 40 μm thickness. Twelve case studies were reported within this research as the applied load of 330 N was tested with three angulations vertical, oblique at 45 degrees, and laterally.

RESULTS

 Twelve linear static stress analyses were performed. The resultant stresses and deformations' distribution patterns did not alter much, and values were within the threshold of physiological tolerance. Deformations were negligibly changed with changing endocrown and cement materials. In contrast, endocrown stresses indicated zirconia endocrown would have a long lifetime, while E-max one will have a relatively short lifetime.

CONCLUSIONS

 Analysis results indicated that bone was negligibly affected by changing endocrowns and cementing materials. Both tested endocrown materials can be used safely. Zirconia endocrowns may have a much longer lifetime than E-max.

Monolithic Zirconia Superstructures in Maxillary All-on-4TM Concept

The aim of the current study was to present the clinical and radiological outcomes of monolithic zirconia superstructures compared to the metal-ceramic ones in the All-on-4 concept for the prosthetic rehabilitation of the maxillae. A total of 30 patients were subdivided into groups according to their superstructure type (metal-ceramic (n = 15) or monolithic zirconia (n = 15)). All implants were functionally loaded within 24 h after insertion with provisional acrylic superstructures. Prosthetic complications, marginal bone loss, plaque accumulation, probing pocket depth, bleeding on probing, and bite force were documented over a period of 5 years. Marginal bone loss around the implants of the ceramic group remained well over the five years (1.21 ± 0.23 mm). However, marginal bone loss was significantly lower around the implants in the monolithic zirconia group (0.22 ± 0.14 mm) (p < 0.001). Bleeding on probing, plaque accumulation, and probing pocket depth values were correlated with marginal bone loss. Among all evaluated parameters, no differences could be detected in terms of the angulation of the implants. Detachment or chipping was observed in seven cases in the metal-ceramic superstructure group. In all cases, dentures were removed and repaired in the laboratory. In the monolithic zirconia group, chipping was detected after one year in two cases, after two years in four cases, and after five years in one case and could be managed by polishing in situ. Monolithic zirconia superstructures presented superior results regarding the parameters evaluated.

Effects of Surface Textures Created Using Additive Manufacturing on Shear Bond Strength Between Resin and Zirconia

PURPOSE

This investigation aimed to assess the impact of additive manufacturing-generated surface textures on zirconia bond strength.

MATERIALS AND METHODS

Zirconia samples (n = 144) fabricated using digital light-processing (DLP) technology were categorized into 6 groups according to the type of surface conditioning (group NN: no designs, no air abrasion; group NY: no designs, with air abrasion; group GN: groove designs, no air abrasion; group GY: groove designs with air abrasion; group HN: hexagon grid, no air abrasion; group HY: hexagon grid, with air abrasion). Composite resin cylinders were cemented to the treated zirconia surfaces with dual-curing, self-adhesive resin cement (Clearfil SA Luting). The shear bond strength (SBS) was tested after water storage for 3 days or 3 days with an additional 10,000 thermocycles.

RESULTS

The zirconia samples fabricated using DLP technology have high accuracy. The SBS of the NY, GY, and HY groups did not significantly differ after 3 days, and neither did the SBS of the NN, GN, and HN groups. The NN, NY, and HY groups exhibited reduced SBS compared to their initial values following artificial aging, while the SBS of the remaining three groups were not diminished. The GY group obtained the highest SBS value after aging.

CONCLUSION

Printing grooves with air abrasion can improve the bond strength.

The possibility of clinical bonding between metal/ceramic brackets to zirconia: in vitro study

Objective: The present study aimed to assess the bond strength and durability of six bonding agents concerning their application to metal or ceramic brackets and zirconia. Materials and Methods: Six resin cement bonding agents (XT, XTS, RSBU, RGBU, SBPM, and GMP) were chosen for this investigation. Specimens were either stored in distilled water at 37°C for 24 h or subjected to 5,000 thermocycles before conducting a Shear Bond Strength (SBS) test. Statistical analysis of the SBS data was performed using three-way ANOVA and Games-Howell tests (α = 0.05). The Adhesive Remnant Index was examined, and the debonding surface details on brackets and zirconia were observed. Results: For metal brackets, all groups demonstrated clinically acceptable bond strength, irrespective of storage conditions, except for the XT group. Regarding ceramic brackets, all groups displayed acceptable bond strength after 24 h of water storage. However, following thermocycling, a significant decrease in SBS was noted across all groups (p < 0.05), with SBPM exhibiting a higher bond strength. Three-way ANOVA analysis indicated that SBS values were notably influenced by each factor, and an interaction among the three independent variables was observed (p = 0.000). Conclusion: The reliable bond strength between ceramic brackets and zirconia was significantly lower after thermocycling compared to that of metal brackets and zirconia. SBPM exhibited consistent and robust bond strength between ceramic/metal brackets and zirconia across various storage conditions. Furthermore, the HEMA-free adhesive demonstrated a potentially more consistent bonding performance compared to the HEMA-containing adhesive employed in this study.

The Effect of Restoration Thickness on the Fracture Resistance of 5 mol% Yttria-Containing Zirconia Crowns

BACKGROUND

To determine what thickness of 5 mol% yttria zirconia (5Y-Z) translucent crowns cemented with different cements and surface treatments would have equivalent fracture resistance as 3 mol% yttria (3Y-Z) crowns.

METHODS

The study included 0.8 mm, 1.0 mm, and 1.2 mm thickness 5Y-Z (Katana UTML) crowns and 0.5 and 1.0 mm thickness 3Y-Z (Katana HT) crowns as controls. The 5Y-Z crowns were divided among three treatment subgroups (n = 10/subgroup): (1) cemented using RMGIC (Rely X Luting Cement), (2) alumina particle-abraded then luted with the same cement, (3) alumina particle-abraded and cemented using a resin cement (Panavia SA Cement Universal). The 3Y-Z controls were alumina particle-abraded then cemented with RMGIC. The specimens were then loaded in compression at 30° until failure.

RESULTS

All 5Y-Z crowns (regardless of thickness or surface treatment) had a similar to or higher fracture force than the 0.5 mm 3Y-Z crowns. Only the 1.2 mm 5Y-Z crowns with resin cement showed significantly similar fracture force to the 1 mm 3Y-Z crowns.

CONCLUSION

In order to achieve a similar fracture resistance to 0.5 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns may be as thin as 0.8 mm. To achieve a similar fracture resistance to 1.0 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns must be 1.2 mm and bonded with resin cement.

Fracture Resistance of Posterior Tooth-Supported Cantilever Fixed Dental Prostheses of Different Zirconia Generations and Framework Thicknesses: An In Vitro Study

The rehabilitation of free-end situations is a frequent indication in prosthetic dentistry. Cantilever fixed dental prostheses (cFDPs) made of 1st and 2nd generation zirconia are one treatment option. Due to a unique gradient technology, combinations of different zirconium dioxide generations are thus feasible in one restoration. However, data about these materials are rare. The purpose of this study was therefore to investigate the fracture resistance and fracture modes of tooth-supported cFDPs fabricated from different zirconia materials (gradient technology) and different framework thicknesses. A total of 40 cFDPs were fabricated using the CAD/CAM approach and belonged to five test groups. The different groups differed in the yttria content, the proportion of the tetragonal/cubic phases, or in wall thickness (0.7 mm or 1 mm). After completion, the cFDPs were subjected to thermal cycling and chewing simulation (1.2 × 106 load cycles, 108 N load). Afterwards, cFDPs were statically loaded until fracture in a universal testing machine. A non-parametric ANOVA was compiled to determine the possible effects of group membership on fracture resistance. In addition, post-hoc Tukey tests were used for bivariate comparisons. The mean fracture loads under axial load application ranged from 288 to 577 N. ANOVA detected a significant impact of the used material on the fracture resistances (p < 0.001). Therefore, the use of cFDPs fabricated by gradient technology zirconia may not be unreservedly recommended for clinical use, whereas cFPDs made from 3Y-TZP exhibit fracture resistance above possible masticatory loads in the posterior region.

Translucent monolithic zirconia titanium-supported FP1 full-arch prosthesis: A novel proof of concept to address esthetic, functional, and biologic challenges

OBJECTIVE

Despite the wide clinical use of translucent zirconia for full-arch implant prostheses, reduced flexural strength and fracture toughness compared with high-strength opaque zirconia needs to be addressed. A novel proof of concept for FP1 full-arch prosthesis featured by translucent monolithic zirconia and titanium framework was presented.

CLINICAL CONSIDERATIONS

Computer-guided implant planning and surgery were executed and digitally designed FP1 temporary prosthesis prefabricated. Implant and prosthetic placement were achieved with a set of three-dimensional (3D)-printed templates. Implants were immediately loaded. After 4 months intraoral optical scan was taken to record implant coordinates, soft tissue anatomy, and temporary FP1 prosthesis. A novel digital workflow was used to design and mill overlaying translucent zirconia and anatomically shaped titanium framework with a scalloped soft-tissue interface. Final FP1 prosthesis was assembled cementing zirconia jacket on titanium counterpart.

CONCLUSIONS

Translucent zirconia supported by titanium framework can address esthetic and mechanical requirements of FP1 full-arch prosthesis, minimizing risk of fracture and providing a rigid and passive joint with supporting implants. The smooth and highly polished titanium surface with an anatomic design, tightly matching scalloped soft tissue interface, can limit food impaction, air and saliva leakage and contribute to overall biologic integration of FP1 full-arch prosthesis.

CLINICAL SIGNIFICANCE

Translucent monolithic zirconia featured with anatomically shaped titanium framework with scalloped transmucosal part, combining a pleasant esthetic outcome with increased flexural strength and fracture toughness, may be indicated to increase the clinical performance of FP1 full-arch prosthesis.

A narrative review

OBJECTIVE

The purpose of this review was to provide dental professionals with information regarding the various types of zirconia restorations, their mechanical and optical properties, tooth preparation design, and bonding protocol in an effort to enhance the longevity and durability of zirconia restorations.

OVERVIEW

The yttria content of zirconia ceramics determines their classification. The mechanical and optical properties of each type are discussed, with an emphasis on the effect of yttria concentration on the properties of zirconia. The processing and sintering methods are also discussed as they have a direct impact on the properties of zirconia. The design of tooth preparation, specifically occlusal reduction, varies depending on the type of zirconia used in each case. Finally, a protocol for zirconia restoration bonding is described to ensure optimal bonding to the tooth structure.

CONCLUSION

Not all zirconia restorations are the same. The selection of zirconia type based on yttria concentration, processing and sintering methods, tooth preparation design, and adherence to the bonding protocol are all critical to the success and longevity of zirconia restorations.

CLINICAL SIGNIFICANCE

Zirconia restorations are the most commonly used indirect restorative material. The selection of the most appropriate zirconia type based on its yttria content, which determines its strength and translucency, is critical to the success and the longevity of the restoration. Tooth preparation design also influences the strength and translucency of the zirconia. Air-borne particle abrasion, followed by a ceramic primer and resin cement, can ensure a durable bond to the tooth structure.

Comparative evaluation of gingival fibroblast growth on 3D-printed and milled zirconia: An in vitro study

PURPOSE

The purpose of this study was to analyze the fibroblast growth and proliferation on 3D-printed zirconia in presence and absence of porosities.

MATERIAL AND METHODS

A total of 40 bars (8 × 4 × 3) were included in this study. Thirty 3D-printed and 10 milled zirconia samples were prepared. The 3D-printed samples had different porosities, 0% (PZ0), 20% (PZ20), and 40% (PZ40) with 10 specimens in each group. Milled zirconia samples were used as the control (MZ). Rat gingival fibroblasts were cultured for 48 h, and the proliferation of fibroblasts on each sample in each group (n = 10) was determined by MTT assays. The differences among the four groups were compared by one-way ANOVA. To test the significance of the observed differences between two groups, an unpaired Student's t-test was applied. The significance level was set at p < 0.05. Qualitative analysis for the cell culture was performed using scanning electron microscopy.

RESULTS

One-way ANOVA showed that the numbers of the fibroblasts among the four groups had a statistical difference. Post hoc Bonferroni test revealed that there was no significant difference between PZ0 and MZ; however, all other groups and among groups were significantly different.

CONCLUSIONS

Fibroblasts had a better affinity toward the MZ and PZ0 in a short period of cell culture time.

Metallic Hand Scalers on Zirconia Implant-Supported Crowns: A Year-Long Analysis of Peri-Implant Maintenance

This study examined whether the degree of abutment surface modification that may occur with regular periodontal instrumentation has a clinical impact in terms of increased plaque accumulation and increased peri-implant tissue inflammation on zirconia implant abutments. Thirteen patients who had zirconia implant crowns were recruited in this randomized clinical trial. Each patient acted as their control and had either the buccal or lingual surface of their screw-retained implant restoration scaled with a metallic scaler and the other surface with a non-metallic scaler at 3, 6, 9, and 12 months. Cytokine testing of the peri-implant crevicular fluid was completed at 0, 3, and 12 months for IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, or IFNγ. Implant crowns were removed at 12 months and evaluated under an atomic force microscope for the average roughness (Ra). The implant crowns were polished and re-inserted. The results were analyzed using the Kruskal-Wallis test, and post hoc tests were conducted with a significance level of α = 0.05. Significant differences in surface roughness (Ra) were observed between the metallic and non-metallic scalers. The median Ra values were 274.0 nm for metallic scalers and 147.1 nm for non-metallic scalers. However, there were no significant differences between the type of scaler used and the amount of clinical inflammation or cytokine production. Metallic scalers produced deeper, more aggressive surface alterations to the abutment/crown zirconia surface, but there was no statistically significant difference between the degree of surface alterations, amount of BOP, and the amplitude of cytokine inflammation produced.

Tensile bond strength of CAD-CAM all ceramic crowns before and after thermomechanical aging

PURPOSE

The purpose of this in vitro study was to compare the tensile bond strength (TBS) of resin nanoceramics (RNC), zirconia, and lithium disilicate (LS2) restorations cemented to titanium abutments before and after thermomechanical aging.

MATERIALS AND METHODS

Twelve specimens per group were fabricated to determine the TBS between a titanium abutment and four types of crown materials (2 RNCs, LS2, and translucent zirconia crowns for the maxillary molar). After milling, the abutments and crowns were cemented with resin cement after air-particle abrasion. In addition, thermomechanical aging (200,000 cycles, 50 N, 2 Hz) was applied to half of the specimens by using a mastication simulator. TBS was measured by using a universal testing machine. The interface between the crown and the cement was observed by using scanning electron microscopy (SEM). Two-way ANOVA was performed to analyze the effects of crown materials and thermomechanical aging. Failure-mode and interface analyses were also conducted.

RESULTS

After thermomechanical aging, the TBS decreased in the LS2 specimens and increased in RNCs (p < 0.001). The ratio of mixed failure and debonding with the hole-sealing resin increased in the RNC group. SEM images showed the reduced gap between the crown and the resin cement after thermomechanical aging in the RNC group.

CONCLUSIONS

Differences in TBS were affected by the crown materials after thermomechanical aging. After thermomechanical aging, the RNC crowns showed increased TBS, whereas LS2 and zirconia crowns exhibited decreased or similar TBS.

The Effect of Sintering on Zirconia Manufactured via Suspension-Enclosing Projection Stereolithography for Dental Applications: An In Vitro Study

BACKGROUND

Zirconia is a widely used material in the dental industry due to its excellent mechanical and aesthetic properties. Recently, a new 3D printing process called suspension-enclosing projection stereolithography (SEPS) was introduced to fabricate zirconia dental restorations. However, the effect of the sintering time and temperature on the properties of zirconia produced via SEPS has not been fully investigated.

METHODS

Zirconia slurries were prepared with varying percentages of zirconia powders and 3D printing resins, and 5Y-TZP (5 mol% yttria-stabilized zirconia) (n = 40) and 3Y-TZP (3 mol% yttria-stabilized zirconia) (n = 40) bar specimens were fabricated via SEPS manufacturing. The specimens were sintered at different temperatures and dwell times, and their flexural strength, density, and phase composition were measured. The viscosity of the slurries was also measured. Statistical analysis was performed using Welch's ANOVA and Kruskal-Wallis tests to evaluate the impact of the sintering conditions.

RESULTS

Significant differences in flexural strength (p < 0.01) were observed between the 5Y-TZP samples, with those sintered at 1530 °C for 120 min showing an average strength of 268.34 ± 44.66 MPa, compared to 174.16 ± 42.29 MPa for those sintered at 1450 °C for 120 min. In terms of density, significant differences (p < 0.01) were noted for the 3Y-TZP specimens, with an average density of 6.66 ± 0.49 g/cm3 for samples sintered at 1530 °C for 120 min, versus 5.75 ± 0.55 g/cm3 for those sintered at 1530 °C for 10 min. X-ray diffraction confirmed the presence of a predominantly tetragonal phase in both materials.

CONCLUSIONS

Zirconia printed via SEPS manufacturing can be sintered at a higher temperature with shorter dwell times, thereby producing high density samples. Different sintering conditions can be used to fully sinter 3D-printed zirconia for potential dental applications.

Frequency Response Evaluation as Diagnostic and Optimization Tool for Pulsed Unipolar Plasma Electrolytic Oxidation Process and Resultant Coatings on Zirconium

This study aims to bridge various diagnostic tools for the development of smart plasma electrolytic oxidation (PEO) technologies. PEO treatments of commercially pure Zr were carried out using the pulsed unipolar polarisation (PUP) regime with frequency sweep in an alkaline phosphate-silicate electrolyte. Methods of in situ impedance spectroscopy and electrical transient analysis were used for the process diagnostics under the video imaging of the PEO. Two cutoff frequencies, 170-190 Hz and 620-650 Hz, were identified for the PEO-assisted charge transfer process. An equivalent circuit for the metal-oxide-electrolyte system under PUP PEO conditions was developed; from the capacitance values, two geometrical dielectric barriers were evaluated: a thinner 0.5-1 µm inner layer of the coating and a thicker 4-6 µm outer layer. These estimates were in agreement with the coating cross-sectional morphology. Based on comparing the results obtained using different techniques, the frequencies at which the uniform coatings with the best protective properties were formed were identified. For the selected electrolyte system and polarisation regime, these frequencies ranged from 2 to 5 kHz where the overall circuit reactance was minimal; therefore, the power factor was as close to one as possible. This opens the possibilities for the optimization of the pulsed PEO process and online control of unobservable surface characteristics, e.g., the thickness of the coating layers, thus contributing towards the development of smart PEO technologies.

A Narrative Review on Polycrystalline Ceramics for Dental Applications and Proposed Update of a Classification System

Dental zirconias have been broadly utilized in dentistry due to their high mechanical properties and biocompatibility. Although initially introduced in dentistry as an infrastructure material, the high rate of technical complications related to veneered porcelain has led to significant efforts to improve the optical properties of dental zirconias, allowing for its monolithic indication. Modifications in the composition, processing methods/parameters, and the increase in the yttrium content and cubic phase have been presented as viable options to improve zirconias' translucency. However, concerns regarding the hydrothermal stability of partially stabilized zirconia and the trade-off observed between optical and mechanical properties resulting from the increased cubic content remain issues of concern. While the significant developments in polycrystalline ceramics have led to a wide diversity of zirconia materials with different compositions, properties, and clinical indications, the implementation of strong, esthetic, and sufficiently stable materials for long-span fixed dental prostheses has not been completely achieved. Alternatives, including advanced polycrystalline composites, functionally graded structures, and nanosized zirconia, have been proposed as promising pathways to obtain high-strength, hydrothermally stable biomaterials. Considering the evolution of zirconia ceramics in dentistry, this manuscript aims to present a critical perspective as well as an update to previous classifications of dental restorative ceramics, focusing on polycrystalline ceramics, their properties, indications, and performance.

Photoluminescence and thermoluminescence properties of pure and rare-earth-doped ZrO2 prepared by Pechini-type sol-gel

In this article, photoluminescence (PL) and thermoluminescence (TL) properties of ZrO2 , ZrO2 :Dy3+ , ZrO2 :Dy3+ -Gd3+ , ZrO2 :Dy3+ -Yb3+ , ZrO2 :Dy3+ -Er3+ , and ZrO2 :Dy3+ -Sm3+ phosphors synthesized by the Pechini method were investigated. The crystal structure, thermal properties, morphology, PL and TL properties were investigated using X-ray powder diffraction (XRD), differential thermal analysis/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), PL and TL, respectively. The room temperature emission bands corresponding to 4 F9/2  → 6 HJ (J = 9/2, 11/2, 13/2 and 15/2) transitions of Dy3+ ions were measured. The phosphors were analysed using Tm -TSTOP , variable dose, and computerized glow curve fitting methods. Reusability, dose-response, and fading characteristics were investigated. The phosphors have a natural TL emission that vanished by heating treatment. Moreover, new peaks with similar properties to the natural emissions were observed after high-dose irradiation and long-term fading experiments. The glow curves of the phosphors have 13 individual peaks and many low- and high-temperature satellite peaks. The origin of the peaks is ZrO2 host material and doping with rare-earth ions (Gd3+ , Dy3+ , Yb3+ , Er3+ and Sm3+ ) does not lead to a new glow peak. The dopants cause drastic changes in individual peak intensities of ZrO2 .The initial fading rates of all the phosphors are relatively fast, but they slow down as time goes on.

Clinical evaluation of zirconia crowns cemented with two different resin cements: A retrospective study

BACKGROUND

Self-adhesive resin cement has been used extensively with zirconia crowns. Several in vitro studies showed that adhesive resin cementation may increase zirconia crowns' retention and their fatigue resistance.

OBJECTIVES

This retrospective study aimed to evaluate the clinical performance, survival and success rates and complications encountered with zirconia crowns cemented with two different self-adhesive resin cements.

METHODS

A total of 112 patients who received 176 monolithic zirconia crowns were evaluated. Crowns were cemented with RelyX Unicem 2 (n = 74) and Panavia SA (n = 102) self-adhesive resin cements. Clinical assessments of the crowns and supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Intraoral photographs and periapical and bitewing radiographs were obtained for further assessment by two evaluators. Descriptive statistics, McNemar, t-test, log rank (Mantel-Cox) tests and Kaplan-Meier survival analyses were performed (a = .05).

RESULTS

The 5-year survival and success rates were 100% and 96.4%, respectively. The complications encountered were recurrent caries (2.2%) and the need for endodontic treatment (0.5%). No technical complications, such as fracture or loss of retention, were observed. The type of cement and patient-related factors did not influence the survival and success rates of the crowns.

CONCLUSIONS

Survival rate of zirconia crowns cemented with two different self-adhesive resin cements was 100% after 5 years.

A Comparison of Failure Loads for Polycrystalline Zirconia Ceramics with Varying Amounts of Yttria, Glass-Ceramics and Polymers in Two Different Test Conditions

It is unclear how zirconia dental crowns with different yttria compositions will perform clinically, and how they will compare with crowns made of glass-ceramics and polymers. The present objective was to determine failure loads of crowns and discs made of glass ceramics or polymers as compared to yttria-partially stabilized zirconia (Y-PSZ) crowns and discs with varying yttria concentrations. Crowns of zirconia (Cercon XT, Katana UTML, BruxZir Anterior), glass ceramic (Celtra press, IPS e.max press, Lisi press), and polymeric materials (Trilor, Juvora, Pekkton) were fabricated and cemented to epoxy abutments. The total number of specimens was 135 for crowns and 135 for discs (n = 15 specimens per material type and design). A universal testing machine was used to perform compressive loading of crowns/discs to failure with a steel piston along the longitudinal axis of the abutments. Energy dispersive spectroscopy (EDS) was used to identify the yttria concentration for each zirconia brand. The data were analyzed using generalized linear models and regression analyses. The results revealed significant differences (p < 0.05) in mean failure loads for different crown materials: Trilor (6811 ± 960 N) > Juvora (5215 ± 151 N) > Cercon (4260 ± 520 N) = BruxZir (4186 ± 269 N) = e.max (3981 ± 384 N) > Katana (3195 ± 350 N) = Lisi (3173 ± 234 N) = Pekkton (3105 ± 398 N) > Celtra (2696 ± 393 N). The general linear model revealed significant differences (p < 0.05) in mean failure loads when comparing the different materials for the discs, i.e., Trilor (5456 ± 1748 N) > Juvora (4274 ± 869 N) > Pekkton (3771 ± 294 N) > Katana (2859 ± 527 N) > Cercon (2319 ± 342 N) = BuxZir (2250 ± 515 N) = e.max (2303 ± 721 N) = Lisi (2333 ± 535 N) > Celtra (1965 ± 659 N). EDS showed that the zirconia materials contained yttria at different concentrations (BruxZir = 5Y-PSZ, Cercon = 4Y-PSZ, Katana = 3Y-PSZ). The yttria concentration had a significant effect on the failure load of the Katana (3Y-PSZ) crowns, which revealed lower failure loads than the Cercon (4Y-PSZ) and BruxZir (5Y-PSZ) crowns, whose failure loads were comparable or higher than e.max glass ceramic. The failure load of the trilayer disc specimens did not correlate with the failure load of the respective crown specimens for the zirconia, glass-ceramic and polymeric materials.

Fully digital workflow for implant-supported fixed restorations consisting of a titanium primary structure and a zirconia secondary structure

PURPOSE

To describe a fully digital workflow for an implant-supported fixed hybrid restoration that involves a double CAD/CAM structure and to highlight the benefits of this type of restoration.

MATERIALS AND METHODS

Using a fully digital workflow, starting from intraoral scans, the necessary steps for producing the final hybrid prosthesis are described. The prosthesis consists of a titanium primary structure and a zirconia secondary structure that is cemented onto the primary structure in the laboratory. A clinical case is presented to illustrate the steps required for prosthetic rehabilitation.

RESULTS

This technique enables the fabrication of clinically valid and passive prostheses using a fully digital workflow.

CONCLUSION

In just three clinical sessions, a fully digital workflow makes it possible to produce robust implant-supported fixed hybrid prostheses, comprising a titanium primary structure and an outer secondary structure made of zirconia. This procedure can be applied to a wide range of cases from simple to extended, including full-arch restorations.

Surface Evaluation of Milled Chairside CAD/CAM Materials Based on Manufacturing Speed

AIM

The aim is to record the surface roughness of monolithic chairside CAD/CAM zirconia materials to evaluate the influence of milling speed on the ability to achieve a clinically desirable surface. The null hypothesis is that there is no significant difference in the surface roughness of different zirconia materials based on the speed of subtractive milling.

MATERIALS AND METHODS

All test samples were milled from four different monolithic CAD/CAM zirconia blocks including CEREC Zirconia (Dentsply Sirona), CEREC Zirconia+ (Dentsply Sirona), CEREC MTL Zirconia (Dentsply Sirona), and Katana Zirconia (Kuraray Noritake). Four different dry milling speeds, Super Fast/Good, Super Fast/Very Good, Fast, and Fine were used to dry mill the specimens in a CEREC Primemill (Dentsply Sirona). A 3D measuring laser microscope (OLS4100 LEXT by Olympus) was used to measure surface roughness.

RESULTS

An Analysis of Variance (ANOVA) was used to analyze the surface roughness data for each material and milling speed. There was a significant difference for milling speed (p < 0.05) but not between zirconia materials (p > 0.05).

CONCLUSION

Based on the limitations of this study, the milling speed influenced the surface roughness of dry milled and sintered zirconia with slower speeds resulting in smoother surfaces. The largest improvement in surface roughness occurred between Super Fast and Fast milling with a smaller incremental improvement in surface roughness with Fine milling for the Primemill. All recorded surface roughness values are within the expected range of values to be able to efficiently hand polish a clinically acceptable surface finish.

Effects of Plasma Treatment on the Strength of Bonding to Ceramic Surfaces in Orthodontics-A Comprehensive Review

Over the past several decades, orthodontic treatment has been increasingly sought out by adults, many of whom have undergone restorative dental procedures that cover enamel. Because the characteristics of restorative materials differ from those of enamel, typical bonding techniques do not yield excellent restoration-bracket bonding strengths. Plasma treatment is an emerging surface treatment that could potentially improve bonding properties. The purpose of this paper is to evaluate currently available studies assessing the effect of plasma treatment on the shear bond strength (SBS) and failure mode of resin cement/composite on the surface of ceramic materials. PubMed and Google Scholar databases were searched for relevant studies, which were categorized by restorative material and plasma treatment types that were evaluated. It was determined that cold atmospheric plasma (CAP) treatment using helium and H2O gas was effective at raising the SBS of feldspathic porcelain to a bonding agent, while CAP treatment using helium gas might also be a potential treatment method for zirconia and other types of ceramics. More importantly, CAP treatment using helium has the potential for being carried out chairside due to its non-toxicity, low temperature, and short treatment time. However, because all the studies were conducted in vitro and not tested in an orthodontic setting, further research must be conducted to ascertain the effectiveness of specific plasma treatments in comparison to current orthodontic bonding treatments in vivo.

Comparison of the Surface Roughness of CAD/CAM Metal-Free Materials Used for Complete-Arch Implant-Supported Prostheses: An In Vitro Study

The roughness of the intra-oral surfaces significantly influences the initial adhesion and the retention of microorganisms. The aim of this study was to analyze the surface texture of four different CAD-CAM materials (two high-performance polymers and two fifth-generation zirconia) used for complete-arch implant-supported prostheses (CAISPs), and to investigate the effect of artificial aging on their roughness. A total of 40 milled prostheses were divided into 4 groups (n = 10) according to their framework material, bio.HPP (B), bio.HPP Plus (BP), zirconia Luxor Z Frame (ZF), and Luxor Z True Nature (ZM). The areal surface roughness "Sa" and the maximum height "Sz" of each specimen was measured on the same site after laboratory fabrication (lab as-received specimen) and after thermocycling (5-55 °C, 10,000 cycles) by using a noncontact optical profilometer. Data were analyzed using SPSS version 28.0.1. One-way ANOVA with multiple comparison tests (p = 0.05) and repeated measures ANOVA were used. After thermocycling, all materials maintained "Sa" values at the laboratory as-received specimen level (p = 0.24). "Sz" increased only for the zirconia groups (p = 0.01). B-BP exhibited results equal/slightly better than ZM-ZF. This study provides more realistic surface texture values of new metal-free materials used in real anatomical CAISPs after the manufacturing and aging processes and establishes a detailed and reproducible measurement workflow.

Biomaterials and Clinical Application of Dental Implants in Relation to Bone Density-A Narrative Review

Titanium has been the material of choice for dental implant fixtures due to its exceptional qualities, such as its excellent balance of rigidity and stiffness. Since zirconia is a soft-tissue-friendly material and caters to esthetic demands, it is an alternative to titanium for use in implants. Nevertheless, bone density plays a vital role in determining the material and design of implants. Compromised bone density leads to both early and late implant failures due to a lack of implant stability. Therefore, this narrative review aims to investigate the influence of implant material/design and surgical technique on bone density from both biomechanical and biological standpoints. Relevant articles were included for analysis. Dental implant materials can be fabricated from titanium, zirconia, and PEEK. In terms of mechanical and biological aspects, titanium is still the gold standard for dental implant materials. Additionally, the macro- and microgeometry of dental implants play a role in determining and planning the appropriate treatment because it can enhance the mechanical stress transmitted to the bone tissue. Under low-density conditions, a conical titanium implant design, longer length, large diameter, reverse buttress with self-tapping, small thread pitch, and deep thread depth are recommended. Implant material, implant design, surgical techniques, and bone density are pivotal factors affecting the success rates of dental implant placement in low-density bone. Further study is required to find the optimal implant material for a clinical setting's bone state.

Influence of straight versus angulated screw channel titanium bases on failure loads of two-piece ceramic and titanium implants restored with screw-retained monolithic crowns: An in-vitro study

OBJECTIVE

To analyze the influence of titanium-base (straight [SSC]/angulated-screw-channel [ASC]) on failure-loads and bending-moments of two-piece ceramic and titanium-zirconium implants restored with monolithic-zirconia crowns after fatigue.

MATERIALS AND METHODS

Thirty-two anterior monolithic-screw-retained zirconia crowns were divided into four groups (n = 8/group) according to the factors: (1) type of implant material: two-piece titanium-zirconium implant (Ti-Zr; control-group) versus two-piece ceramic implant (CI; test-group) and (2) type of titanium-base: SSC (0° angle) versus ASC (25°). An intact implant was used for field emission gun-scanning electronic microscopy (FEG-SEM) characterization and Raman spectroscopy for phase analyses and residual stress quantification. All samples were exposed to fatigue with thermodynamic loading (1.2-million-cycles, 49 N, 1.6 Hz, 5-55°C) at a 30° angle. Surviving specimens were loaded until failure (SLF) and bending moments were recorded. Failed samples were examined using light microscope and SEM. Statistical analyses included ANOVA and Mann-Whitney U-test.

RESULTS

Raman-spectroscopy revealed the presence of residual compressive stresses. FEG-SEM revealed a roughened surface between threads and polished surface at the cervical-collar of the ceramic implant. All samples survived fatigue and were free of complications. Mean bending-moments (±SD) were: Ti-Zr-0: 241 ± 45 N cm, Ti-Zr-25: 303 ± 86 N cm, CI-0: 326 ± 58 N cm, CI-25: 434 ± 71 N cm. Titanium-base and implant-material had significant effects in favor of ASC titanium bases (p = .001) and ceramic-implants (p < .001). Failure analysis after SLF revealed severe fractures in ceramic implants, whereas titanium implants were restricted to plastic deformation.

CONCLUSIONS

Ceramic and titanium implants exhibited high reliability after fatigue, with no failures. From a mechanical perspective, titanium bases with ASC can be recommended for both ceramic and titanium implants and are safe for clinical application.

An In vitro study

Objectives To evaluate and compare bacterial growth on zirconia versus titanium healing caps. Material and methods S. sanguinis (Ss) and F. nucleatum (Fn) were grown on titanium and zirconia healing caps that were fixed to the cover of a 96-well microtiter plate. A drop (10 μL) of bacterial suspension was placed on each healing cap and allowed to dry for 1h at 37°C. After this time, the cover was replaced on the plate such that the caps were completely immersed in fresh liquid medium. Each plate contained only one bacterial strain, with 2 control groups. Bacterial growth was monitored over 18h by following the optical density at 650nm. A one-way ANOVA comparison test was used for statistical analysis. Scanning electron microscope (SEM) images of healing caps of each material were taken after a 48h incubation with Ss or Fn to assess bacterial attachment and with no bacteria as control. Results Ss growth was similar in both types of healing cap with no significant differences between these groups and the control (P=0.990). However, there was significantly less growth of Fn on the zirconia caps than on the titanium samples (P<0.0001) or the control (P<0.0001). SEM imaging revealed obvious differences in the surface characteristics of the titanium and zirconia caps. The number of bacteria attached to the rough apical area was particularly high. Conclusions The use of zirconia healing caps may reduce the growth of some bacterial species compared to that seen on titanium healing caps.

Dental Implant Treatment in Bruxers: A Case Report and Literature Review

This case report presents a literature review and a case report of a full-mouth implant rehabilitation for a 65-year-old woman with a history of Bruxism. The patient's oral condition showed dentition with severe occlusal wear, extensive dental work, and missing teeth replaced with bridges and implants. The existing dental work was failing due to recurrent caries and the mechanical failure of long-span bridges. The unique aspect of the treatment presented in this report is the management of existing osseointegrated implants of different systems with different platform designs, which adds to the treatment's complexity. The existing implants were incorporated into the planned treatment, and other implants were added to support maxillary zirconia and mandibular hybrid full-arch prostheses. After 2 years of function, extensive wear was evident on the milled acrylic, even though an occlusal guard was used. New acrylic teeth were processed using the same milled titanium bar of the mandibular hybrid prosthesis, and the occlusal surfaces of the acrylic teeth were protected with gold onlays. The patient is seen regularly for maintenance every 6 months with no further complications. Careful evaluation, planning, and treatment execution are paramount in managing patients with a history of bruxism. Patients should be prepared and informed about possible mechanical failure and seen regularly for maintenance.

Marginal Accuracy of Monolithic and Veneered Zirconia Crowns Fabricated by Conventional and Digital Workflows

PURPOSE

To compare the marginal accuracy of zirconia crowns fabricated by different workflows (conventional and digital) and designs (monolithic and veneered).

MATERIALS AND METHODS

A prepared maxillary first molar was used for the study. Four workflow combinations were evaluated: (1) intraoral scanning and monolithic zirconia (IOS-M), (2) intraoral scanning and veneered zirconia (IOS-V), (3) conventional impression and monolithic zirconia (IMP-M), and (4) conventional impression and veneered zirconia (IMP-V). All of the specimens had similar designs. The veneered groups had a buccal cutback for esthetic veneer application. A total of 10 crowns were produced in each workflow. The vertical and horizontal marginal accuracies were measured with a traveling microscope. Depending on the normality of the data, one-way analysis of variance test or Kruskal-Wallis test were applied to evaluate the differences among the groups (α = 0.05).

RESULTS

The most superior vertical marginal accuracy was observed for IOS-V (mean = 22.5 μm; SD = 6.7 μm), followed by IMP-V (mean = 23.9 μm; SD = 7.8 μm), IOS-M (mean = 28.7 μm; SD = 10.3 μm), and IMP-M (mean = 39.8 μm; SD = 22.0 μm), respectively (p < 0.001). The IOS-M had the greatest mean horizontal discrepancies (mean = 23.9 μm; SD = 4.3 μm) followed by IMP-M (mean = 21.3 μm; SD = 5.7 μm), IMP-V (mean = 19.2 μm; SD = 5.3 μm) and IOS-V (mean = 17.6 μm; SD = 5.7 μm) (p < 0.001).

CONCLUSIONS

Monolithic zirconia crowns fabricated digitally had superior marginal accuracy than monolithic zirconia crowns fabricated conventionally. Esthetic buccal veneering of predominantly monolithic zirconia copings improved the vertical and horizontal marginal accuracies.