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Purpose: To investigate whether the wettability of two zirconia (Zr) implant disk surfaces is affected by glycine and erythritol air polishing using the following wetting solutions as test mediums: saline, bovine serum albumin (BSA), bovine thrombin, and bovine artificial blood., Materials and Methods: The two types of Zr disks used were SDS (Swiss Dental Solutions; n = 6) and Patent (Zircon Medical AG; 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 (EMS Dental). The wettability of the disk surfaces was evaluated by the contact angle analysis applied to the treated and untreated disks using four wetting solutions, including saline, 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 one-way ANOVA and the post-hoc Tukey HSD test., Results: The results indicate that 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 Zr disks more than glycine. BSA and bovine artificial blood had lower contact angles than saline and bovine thrombin for both types of untreated disks., Conclusions: The initial wettability of Zr disks differs between manufacturers, and air polishing with erythritol powder increases the wettability of Zr implant disks for saline, bovine serum, bovine thrombin, and bovine artificial blood.

Despite the significant recent advances in manufacturing materials supporting advanced dental therapies, peri-implantitis still represents a severe complication in dental implantology. Herein, a sol-gel process is proposed to easily deposit antibacterial zirconia coatings onto bulk zirconia, material, which is becoming very popular for the manufacturing of abutments. The coatings' physicochemical properties were analyzed through x-ray diffraction and scanning electron microscopy-energy-dispersive x-ray spectroscopy investigations, while their stability and wettability were assessed by microscratch testing and static contact angle measurements. Uniform gallium-doped tetragonal zirconia coatings were obtained, featuring optimal mechanical stability and a hydrophilic behavior. The biological investigations pointed out that gallium-doped zirconia coatings: (i) displayed full cytocompatibility toward human gingival fibroblasts; (ii) exhibited significant antimicrobial activity against the Aggregatibacter actinomycetemcomitans pathogen; (iii) were able to preserve the commensal Streptococcus salivarius. Furthermore, the proteomic analyses revealed that the presence of Ga did not impair the normal oral microbiota. Still, interestingly, it decreased by 17% the presence of Fusobacterium nucleatum, a gram-negative, strictly anaerobic bacteria that is naturally present in the gastrointestinal tract. Therefore, this work can provide a valuable starting point for the development of coatings aimed at easily improving zirconia dental implants' performance., (© 2024 Wiley Periodicals LLC.)

The connection structure of zirconia dental implants significantly influences their biomechanical behavior and plays a crucial role in the overall service performance of the implant system. This study aims to compare the stress distribution of zirconia implants featuring various internal connection structures under different working conditions. Four distinct types of connection structures were designed for zirconia dental implants: triangular, quadrilateral, hexagonal, and hexalobular plus connections. Additionally, the finite element method was employed to analyze these structures under three working conditions: a static load test model, a bone level model, and a torsion model. Results indicated that in the static load test model, the hexagonal structure experienced the highest stress value at 1284.9 MPa due to its thin neck wall, whereas the hexalobular plus connected implant exhibited the lowest stress value at 1252.9 MPa. In the bone level model, the triangular connection structure demonstrated poor stress distribution for cortical bone and cancellous bone at 69.606 MPa and 7.8191 MPa, respectively. Conversely, the hexalobular plus connection yielded superior stress results for cortical bone and cancellous bone, with values of 66.24 MPa and 5.1327 MPa, respectively. In the torsion model, the hexalobular plus-connected implant exhibits the highest stress value at 237.6 MPa, while maintaining the smallest force transmission angle. Therefore, given that the abutment necessitates a greater range of installation angles and improved torque transmission, the hexalobular plus connection structure may represent the optimal choice., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Achieving robust soft tissue integration around dental implants is crucial for long-term clinical success, as it forms a protective biological seal against bacterial invasion. However, the soft tissue attachment to implants is relatively deficient compared to natural teeth, particularly in the connective tissue region lacking sufficient gingival fibroblasts and collagen fiber alignment. This study proposed an innovative strategy to enhance peri‑implant soft tissue integration by modulating gingival fibroblast behavior via photothermal conversion. Zirconia surfaces were coated with polydopamine (PDA), a melanin-like polymer exhibiting near-infrared (NIR) absorption for photothermal conversion. Under NIR irradiation, the PDA coating enabled mild hyperthermia (42-43 °C) on the zirconia surface. Remarkably, this mild photothermal stimulation significantly promoted human gingival fibroblast proliferation, adhesion, and collagen production compared to unmodified zirconia in vitro. By utilizing the photothermal properties of PDA coatings to modulate cellular behaviors beneficial for connective tissue formation, this approach provides a promising avenue to achieve improved soft tissue integration and long-term stability of dental implants. The findings highlight the innovative potential of combining biomaterial surface engineering with photothermal therapy for applications in implant dentistry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Background and Objectives : The influence of the quantity and quality of peri-implant soft tissue on implant health and long-term maintenance is controversial. This consensus aimed to assess the importance of peri-implant soft tissue by analyzing four aspects: the role of keratinized mucosa (KM), the efficacy of specific collagen matrix, the influence of abutment material, and soft-tissue thickness. Materials and Methods : Active members of the Italian Academy of Osseointegration (IAO) participated in the consensus. Four systematic reviews were conducted, and their results were discussed to provide guidelines on the importance of soft tissue around implants. The first review evaluated the effect of KM on soft-tissue health, peri-implant bone loss, and patient-related variables. The second one analyzed if there was a specific type of matrix that provided better results in terms of peri-implant buccal soft-tissue thickness and keratinized mucosa width compared to autogenous soft-tissue graft. The third review evaluated the influence of different abutment materials on the soft tissues, and the fourth assessed the effect of soft-tissue thickness on peri-implant marginal bone loss (MBL). Results and Conclusions : The agreements reached by the assembly were as follows: the presence of supra-periosteal keratinized tissue is considered to favorably influence peri-implant health and aesthetics but had no relation to preventing bone crest resorption unrelated to infection. It facilitates patient cleaning around implants and reduces patient-reported pain. The free gingival graft (FGG) is considered the best in terms of supra-periosteal KM increase. Connective tissue grafts (CTG) perform better than volume-stable collagen matrices to increase soft-tissue thickness. Collagen matrices reduce surgical time and patient morbidity and can give better camouflaging. The influence of abutment material (titanium or zirconia) on MBL remains controversial, and no conclusion could be reached on this issue. Peri-implant soft-tissue health and recession seem not to be influenced by abutment material, but data are limited to zirconia and titanium. Although this systematic review highlighted the absence of a correlation between soft-tissue thickness and MBL, the assembly failed to find a consensus on this issue.

The glass infiltration technique was employed for surface modification of zirconia implants in this study. The prepared glass-infiltrated zirconia with low infiltrating temperature showed excellent mechanical properties and enough infiltrating layer. The zirconia substrate was pre-sintered at 1,200°C and the glass infiltration depth reached 400 μm after infiltrating at 1,200°C for 10 h. The infiltrating glass has good wetting ability, thermal expansion match and good chemical compatibility with the zirconia substrate. Indentation fracture toughness and flexural strength of the dense sintered glass-infiltrated zirconia composite are respectively 5.37±0.45 MPa•m 1/2 and 841.03±89.31 MPa. Its elasticity modulus is 163.99±7.6 GPa and has about 500 μm infiltrating layer. The glass-infiltrated zirconia can be acid etched to a medium roughness (1.29±0.09 μm) with a flexural strength of 823.65±87.46 MPa, which promotes cell proliferation and has potential for dental implants.

Finite element analysis assists in the understanding of the biomechanical behavior of implants with different designs and material characteristics. Through this analysis, this study aimed to compare the biomechanical behaviors of different designs and configurations of titanium (tapered or cylindric) and zirconia dental implants in the edentulous anterior maxilla. Three-dimensional models of the edentulous maxilla, dental implants, and prosthetic structures were modeled, and different loading conditions were applied to simulate realistic conditions. A total of 6 different models were evaluated: the model (M1) in which tapered implants were located bilaterally in the central canine, the model (M2) in which tapered implants were located bilaterally in the lateral canine, the model (M3) in which cylindric implants were located bilaterally in the central canine, the model (M4) in which cylindric implants were located bilaterally in the lateral canine, the model (M5) in which zirconia implants were located bilaterally in the central canine, and the model (M6) in which zirconia implants were located bilaterally in the lateral canine. Maximum tensile and compressive stress values were recorded at M4 under vertical loading and at M6 under oblique loading, whereas minimum stress values were recorded at M1 under all loading conditions. Maximum von Mises stress values under vertical and oblique loading conditions were observed at M3 and M4, while the minimum stress was observed at M1 and M2. In conclusion, zirconia implants may present a biomechanically convenient and esthetic alternative treatment option in edentulous anterior maxilla rehabilitation compared with tapered and cylindric implants.

Background: The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA)., Methods: Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300 N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading., Results: The highest von Mises stresses in implant (111.6 MPa) and bone (100.0 MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9 MPa) and bone (19.6 MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105 MPa), while the least stresses in prosthesis (35.4 MPa) were recorded in fixed fixed models with PEKK material., Conclusions: In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever., (© 2024. The Author(s).)

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., (© 2023 by the American College of Prosthodontists.)

Objectives: The single-energy metal artifact reduction (SEMAR) algorithm effectively reduces metal artifacts in computed tomography (CT). The study aimed to evaluate the effect of the occlusal plane angle on metal artifacts caused by dental implants and zirconia upper structures, and the effectiveness of SEMAR for CT prognostic evaluation., Methods: Part of a bovine rib was used as the mandibular implant phantom. First, the phantom immersed in a water tank was scanned using CT to obtain the control image under certain conditions. Subsequently, three titanium implant bodies were implanted in a straight line into the phantom, and a zirconia superstructure was attached. CT scans were performed. The CT-reconstructed images were obtained with and without SEMAR processing. Twelve regions of interest (ROIs) were set at the same site on each sagittal image, and the CT values were measured at all the ROIs. The CT values of the ROIs in the control images and those of the ROIs with and without SEMAR were compared., Results: The variations in the occlusal plane angle during CT imaging negligibly affected the number of regions in which metal artifacts appeared. SEMAR improved the CT value of the trabecular bone, which was affected by metal artifacts., Conclusion: This study showed that the occlusal plane angle occasionally did not affect the area of metal artifacts caused by dental implants or zirconia upper structures. Other results indicate that SEMAR is effective for accurately evaluating the alveolar bone around the implant body by reducing metal artifacts., (© 2023. The Author(s) under exclusive licence to Japanese Society for Oral and Maxillofacial Radiology.)

Background: The use of dental implants in the treatment of edentulous patients is increasing. Zirconia implants are an alternative to titanium implants, offering advantages in terms of aesthetics and biological compatibility. However, the number of artifacts observed on radiographic images with zirconia implants compared to titanium implants is yet to be determined., Objectives: The purpose of this study was to evaluate the impact of different cone-beam computed tomography (CBCT) parameters on the production of artifacts in zirconia and titanium implants., Material and Methods: A dry human mandible was coated with wax to simulate human soft tissues and examined. Subsequently, titanium and zirconia implants were placed at the same points in the posterior region of the mandible. The production of artifacts on CBCT scans was evaluated using 2 parameters. The first parameter, the standard deviation within the region of interest (SDROI), is based on a comparison of the gray levels at implant and control areas. The second parameter was the contrast-to-noise ratio (CNR), which was evaluated for different protocols created by various combinations of the field of view (FOV) area, milliampere [mA] intensity and metal artifact reduction (MAR) programs., Results: The study found that zirconia implants produced more artifacts than titanium implants. However, the production of artifacts in zirconia implants could be significantly reduced by increasing the mA values, performing CBCT scans with smaller FOV areas, and enabling MAR programs., Conclusions: The production of artifacts is a disadvantage of zirconia implants, but this drawback can be mitigated by selecting appropriate protocols for the CBCT device.

Purpose: The aim of this study was to evaluate the surface wear and retention force of telescopic attachments made of zirconia primary crowns and poly-ether- ketone -ketone (PEKK) secondary crowns for 2-implant retained mandibular complete overdentures., Materials and Methods: Ten healthy completely edentulous patients aged 55-60 years were selected for this study. Each patient received two implants in the mandibular canine regions. Maxillary conventional complete dentures were constructed against implant-retained mandibular overdentures for all patients. Zirconia- PEKK telescopic attachments were fabricated to retain the overdentures where primary copings were constructed of zirconia and secondary ones were constructed of PEKK. Retention force and surface wear were evaluated at the time of overdenture insertion (T0), and after 6 months of overdenture use (T6)., Results: The results revealed less wear of zirconia copings compared to PEKK ones at T0 and T6. However, both materials showed insignificant wear after 6 months of overdenture use. A significant increase in retention force was observed after 6 months of overdenture use., Conclusion: Within limitations of this study, PEKK may be considered a promising alternative material for telescopic secondary crowns construction combined to zirconia primary ones, regarding the wear resistance and the satisfactory retention forces., (Copyright© 2024 Dennis Barber Ltd.)

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., (© 2024 Wiley Periodicals LLC.)

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., (© 2023 by the American College of Prosthodontists.)

Background: While conventional threaded implants (TI) have proven to be effective for replacing missing teeth, they have certain limitations in terms of diameter, length, and emergence profile when compared to customised root analogue implants (RAI). To further investigate the potential benefits of RAIs, the aim of this study was to experimentally evaluate the micromotion of RAIs compared to TIs., Methods: A 3D model of tooth 47 (mandibular right second molar) was segmented from an existing cone beam computed tomography (CBCT), and a RAI was designed based on this model. Four RAI subgroups were fabricated as follows: 3D-printed titanium (PT), 3D-printed zirconia (PZ), milled titanium (MT), milled zirconia (MZ), each with a sample size of n = 5. Additionally, two TI subgroups (B11 and C11) were used as control, each with a sample size of n = 5. All samples were embedded in polyurethane foam artificial bone blocks and subjected to load application using a self-developed biomechanical Hexapod Measurement System. Micromotion was quantified by analysing the load/displacement curves., Results: There were no statistically significant differences in displacement in Z-axis (the loading direction) between the RAI group and the TI group. However, within the RAI subgroups, PZ exhibited significantly higher displacement values compared to the other subgroups (p < 0.05). In terms of the overall total displacement, the RAI group showed a statistically significant higher displacement than the TI group, with mean displacement values of 96.5 µm and 55.8 µm for the RAI and TI groups, respectively., Conclusions: The RAI demonstrated promising biomechanical behaviour, with micromotion values falling within the physiological limits. However, their performance is less predictable due to varying anatomical designs., (© 2024. The Author(s).)

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., (© 2023 Wiley Periodicals LLC.)

Background: Titanium is a commonly used material for dental implants owing to its excellent biocompatibility, strength-to-weight ratio, corrosion resistance, lightweight nature, hypoallergenic properties, and ability to promote tissue adhesion. However, alternative materials, such as titanium alloys (Ti-Al-2 V) and zirconia, are available for dental implant applications. This study discusses the application of Density Functional Theory (DFT) in evaluating dental implant materials' mechanical properties and structural stability, with a specific focus on titanium (Ti) metal. It also discusses the electronic band structures, dynamic stability, and surface properties. Furthermore, it presents the mechanical properties of Ti metal, Ti-Al-2 V alloy, and zirconia, including the stiffness matrices, average properties, and elastic moduli. This research comprehensively studies Ti metal's mechanical properties, structural stability, and surface properties for dental implants., Methods: We used computational techniques, such as the CASTEP code based on DFT, GGA within the PBE scheme for evaluating electronic exchange-correlation energy, and the BFGS minimization scheme for geometry optimization. The results provide insights into the structural properties of Ti, Ti-Al-2 V, and zirconia, including their crystal structures, space groups, and atomic positions. Elastic properties, Fermi surface analysis, and phonon studies were conducted to evaluate the tensile strength, yield strength, ductility, elastic modulus, Poisson's ratio, hardness, fatigue resistance, and corrosion resistance., Results: The findings were compared with those of Ti-Al-2 V and zirconia to assess the advantages and limitations of each material for dental implant applications. This study demonstrates the application of DFT in evaluating dental implant materials, focusing on titanium, and provides valuable insights into their mechanical properties, structural stability, and surface characteristics., Conclusions: The findings of this study contribute to the understanding of dental implant material behavior and aid in the design of improved materials with long-term biocompatibility and stability in the oral environment., (© 2023. The Author(s).)

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.

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., (© 2023 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

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.

Objectives: This retrospective case series aimed to evaluate the short-term clinical advantages and limitations of full-arch implant-supported restorations made of monolithic zirconia suprastructures passively luted to titanium bar infrastructures and to report the rate of complications within a minimum of 1-year follow-up., Materials and Methods: This study included 31 patients (19 men and 12 women) requiring full-arch implant-supported prostheses in the upper or lower jaw. The patients were treated using an entirely digital approach from implant planning and guided implant placement to prosthetic construction planning, design, and fabrication. Full-arch implant-supported monolithic zirconia suprastructures luted to prism-shaped titanium bars were used in all the cases. All the restorations were evaluated for biological and technical complications during fixed control appointments., Results: No implant failures or serviceable prosthetic complications were reported, and the prosthetic survival rate was 100%, with a follow-up duration ranging from 12 months to 20 months. In two cases, a fracture line was observed in the zirconia suprastructures, although it did not require any intervention., Conclusions: After a 16-month mean follow-up period, the monolithic zirconia implant-supported full-arch fixed dental prostheses demonstrated no biological or technical complications. Further clinical studies with long-term results are required to confirm these reported outcomes., Clinical Significance: CAD-/CAM-milled monolithic zirconia structures passively luted to titanium bar infrastructures are a viable treatment option for full-arch restorations over implants, demonstrating 100% survival and success rates in the present study. The outcomes of this short-term retrospective study indicated high success in function, aesthetics, phonetics, and the ability to maintain flawless hygiene. However, the long-term results of restorations produced using the proposed technique should be considered before recommending this approach for routine clinical use., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Objectives: Long-term studies of modern zirconia implants are still insufficient. This prospective 8-year follow-up study investigated one-piece zirconia implants., Materials and Methods: Patients who had received a one-piece zirconia dental implant (PURE ceramic implant, Institut Straumann GmbH, Basel, Switzerland) were included in this study. Next to the implant survival and success rates, the radiographic and clinical implant parameters were assessed., Results: The overall survival rate of 67 zirconia implants in 39 patients was 100%. The overall success rate was 89.6%. Around the immediate zirconia implants, the success rate was 94.7%, and around the delayed implants, 87.5%. The immediate implants showed a significantly higher bone crest compared to the delayed implants (p = 0.0120). According to the pink esthetic score, the immediate implants revealed more favorable esthetic results compared to the delayed implants after an 8-year follow-up (p = 0.0002)., Conclusions: After 8 years, the one-piece zirconia implants presented an 89.6% success rate. Regarding the timing of implantation, in individual cases, immediate implantation can have slight advantages over delayed implantation., Clinical Relevance: Immediate implants can also be considered for zirconia implants and should not be excluded on principle., (© 2023. The Author(s).)

3 mol% yttria-stabilized zirconia ceramics have been gaining attention as promising restorative materials that are extensively used in dental implant applications. However, implant failure due to bacterial infection and its bioinert surface slow osseointegration in vivo, which are significant issues in clinical applications. In this work, surface modification was achieved using a continuous wave carbon dioxide laser at a wavelength of 10.6 µm in an air atmosphere. Changes in the surface characteristics were evaluated using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and 2D roughness and hardness tests. The bioactivity of the laser-treated samples was studied by examining their behavior when immersed in the SBF solution. The formation of the hydroxyapatite phase on the laser-treated sample was much more uniform than that of its untreated counterparts. The antibacterial properties of surface-treated zirconia ceramics against Streptococcus mutans and Escherichia coli bacteria were rigorously examined. These results indicate that the laser-induced nanoscale grooves significantly improved antibacterial activity by creating hydrophobic surfaces. The cellular response was evaluated for 7 days on microtextures on the zirconia surfaces and an untreated sample with MC3T3-E1 pre-osteoblast cell line cultured under basal conditions. Surface topography was revealed to improve the cellular response with increased metabolic activity compared to the untreated sample and showed modulation of cell morphology for the entire time. These results suggest that laser modification can be an appropriate non-contact method for designing nanoscale microtextures to improve the biological response and antibacterial behavior of zirconia ceramics in restorative dentistry., (© 2022. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Objectives: The purpose of this study was to investigate the survival rate, the debonding resistance, and the failure modes of different occlusal veneer designs when used as a retainer for posterior cantilever, resin-bonded fixed dental prostheses (RBFDPs) at two tooth wear levels., Methods: Four test groups were assigned: two groups with occlusal-proximal preparation (PT1 and PT2 for grade 2 and 3 wear), and two groups for occlusal-proximal and lingual preparation (PLT1 and PLT2 for grade 2 and 3 wear) Monolithic zirconia ceramic (3Y-TZP) RBFDPs were luted with an adhesive bonding system (Panavia V5). The specimens underwent a chewing simulation for 1.200.000 cycles with a load of 5 kg and thermocycling for 7500 cycles between 5 °C and 55 °C. The surviving restorations were debonded under quasi-static conditions. The results were analyzed with ANOVA., Results: The specimens exhibited a 100 % survival rate after thermomechanical fatigue loading. The debonding resistance was statistically significant higher for group PLT1 than for group PT1 (P = 0.004), and higher for group PT2 than group PT1 (P ≤ 0.001). However, the debonding resistance showed no statistically significant difference between groups PT2 and PLT2 (P = 0.343), and groups PLT1 and PLT2 (P = 0.222). Groups PT1 and PT2 showed favorable failure modes in 62.5 % and 0.00 % of the specimens, respectively. While groups PLT1 and PLT2 presented 25 % favorable failure modes., Significance: Occlusal veneers showed promising results as a retainer for cantilever RBFDPs. The lingual extension might increase debonding resistance. Nevertheless, conservative designs with lingual and proximal bevels are to be recommended, irrespective of the level of tooth wear., (Copyright © 2023 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Background: Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium and ceramic implant abutments due to its apparent ability to dissipate excessive strain around dental implants. However, the biomechanical behaviors of implant abutment crown systems may change depending on the crown and abutment material combinations used., Objectives: This study aimed to assess how the crown material affects strain generation and fracture resistance of PEKK hybrid abutment crowns., Material and Methods: Sixteen dummy implants (Ø 3.7 x 11 mm), simulating maxillary first premolars, were restored with 16 milled PEKK hybrid abutments and randomly categorized into two groups according to the crown material (n = 8): Group C, milled composite crowns cemented on PEKK hybrid abutments; and Group Z, ultra-translucent zirconia crowns cemented on PEKK hybrid abutments. Before thermocycling, a cyanoacrylate-base adhesive was used to position two strain gauges on buccal and lingual crestal bone surfaces, and a vertical load (100 N) was applied to the central fossa to record the strain generated. Then, all samples were thermocycled between 5°C and 55°C before being loaded to fracture on a universal testing machine. Modes of failure were observed under an optical microscope, and representative samples were examined using a scanning electron microscope. Independent t-tests were used for intergroup comparisons. The significance level was set at (p < 0.05) for all tests.., Results: The results showed a significant difference between both groups. The zirconia group recorded significantly higher strain and fracture resistance values than the composite group (p < 0.001). There was a positive correlation between the strain developed in peri-implant crestal bone and fracture resistance of the abutment crown complex., Conclusions: Strains developed in both groups were within the acceptable clinical range. The crown material substantially impacted the strain and fracture of the PEKK hybrid abutment crown system.

Zirconia is a promising material for dental implants; however, an appropriate surface modification procedure has not yet been identified. Atomic layer deposition (ALD) is a nanotechnology that deposits thin films of metal oxides or metals on materials. The aim of this study was to deposit thin films of titanium dioxide (TiO 2 ), aluminum oxide (Al 2 O 3 ), silicon dioxide (SiO 2 ), and zinc oxide (ZnO) on zirconia disks (ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn, respectively) using ALD and evaluate the cell proliferation abilities of mouse fibroblasts (L929) and mouse osteoblastic cells (MC3T3-E1) on each sample. Zirconia disks (ZR; diameter 10 mm) were fabricated using a computer-aided design/computer-aided manufacturing system. Following the ALD of TiO 2 , Al 2 O 3 , SiO 2 , or ZnO thin film, the thin-film thickness, elemental distribution, contact angle, adhesion strength, and elemental elution were determined. The L929 and MC3T3-E1 cell proliferation and morphologies on each sample were observed on days 1, 3, and 5 (L929) and days 1, 4, and 7 (MC3T3-E1). The ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn thin-film thicknesses were 41.97, 42.36, 62.50, and 61.11 nm, respectively, and their average adhesion strengths were 163.5, 140.9, 157.3, and 161.6 mN, respectively. The contact angle on ZR-Si was significantly lower than that on all the other specimens. The eluted Zr, Ti, and Al amounts were below the detection limits, whereas the total Si and Zn elution amounts over two weeks were 0.019 and 0.695 ppm, respectively. For both L929 and MC3T3-E1, the cell numbers increased over time on ZR, ZR-Ti, ZR-Al, and ZR-Si. Particularly, cell proliferation in ZR-Ti exceeded that in the other samples. These results suggest that ALD application to zirconia, particularly for TiO 2 deposition, could be a new surface modification procedure for zirconia dental implants.

Objective: The objective of this study was to investigate the survival and biological and mechanical complications of one-piece and two-piece zirconia implants at five years of loading., Materials and Methods: Consecutive patients receiving zirconia implants were studied, collecting data at five years of loading on their clinical history, peri-implant health status, mechanical complications, esthetic results, and patient related outcomes., Results: The study included 18 patients with 29 implants. The survival rate was 86% in implant-based analysis and 78% in patient-based analysis. There were no cases of peri-implantitis, but mucositis was present in 53% of implants. A mean of 4.1 ± 0.81 mm was obtained for probing depth and 1.6 ± 0.9 mm for crestal bone loss (radiographic assessment). There were no implant fractures. Major (10%) and minor (10%) prosthesis complications were observed. The esthetic outcome was moderate to almost perfect, with a high level of patient satisfaction. No significant association was found between survival rate and the presence of mucositis around one- or two-piece implants or any other study variable., Conclusions: The survival rate is low for one- and two-piece zirconia implants. Both types of implants demonstrated a low mechanical complication rate. The incidence of periimplantitis is low but mucositis is present in 50%. Patient satisfaction related to esthetics and function is moderate to high. They represent a good option for patients requiring an alternative to titanium implants., Clinical Relevance: Zirconia implants appear to be an alternative to the titanium option and may be indicated for patients requiring "metal-free" restorations., (© 2022 Wiley Periodicals LLC.)

Background: It is unclear which crown materials are optimum to disperse the generated stresses around dental implants. The objective of this study is to assess stress distribution and fracture resistance of green reprocessed Polyetheretherketone (PEEK) in comparison to un-reprocessed PEEK and zirconia single implant crown restorations., Methods: Twenty crowns (n = 20) were obtained, five from zirconia and fifteen from pressed PEEK that were subdivided into 3 groups of five specimens each (n = 5) according to weight% of reprocessed material used. A 100% new PEEK was used for the first group, 50% new and 50% reprocessed PEEK were used for the second group, and a 100% reprocessed PEEK was used for the third group. Epoxy resin model with dental implant in the second mandibular premolar was constructed with strain gauges located mesially and distally to the implant to record strain while a load of 100 N was applied with 0.5 mm/min then specimens of all groups were vertically loaded till failure in a universal testing machine at cross head speed 1 mm/min. Data was statistically analyzed by using One-way Analysis of Variance (ANOVA) followed by Post-hoc test when ANOVA test is significant., Results: No significant difference between strain values of tested groups (p = 0.174) was noticed. However, a significant difference between fracture resistance values was noticed where the zirconia group recorded a significantly higher value (p < 0.001)., Conclusions: Implant restorative materials with different moduli of elasticity have similar effects regarding stresses distributed through dental implant and their surrounding bone. Reprocessed PEEK implant restorations transmit similar stresses to dental implant and surrounding bone as non-reprocessed PEEK and zirconia restorations. Zirconia failed at higher load values than all tested PEEK restorations but all can be safely used in the posterior area as crown restorations for single implants., Clinical Relevance: Applying "green dentistry" principles may extend to include reprocessing of pressed PEEK restorative materials without affecting the material's shock absorption properties., (© 2023. The Author(s).)

A 50-year-old man sought treatment for missing maxillary second premolar and first molar teeth. Treatment planning software demonstrated that the mesiodistal space of the edentulous ridge was insufficient to receive 2 implants. A screw-retained, single-implant-supported zirconia fixed partial denture with a mesial cantilever extension was used to replace the 2 missing posterior teeth. This prosthesis, produced with a computer-aided design/computer-aided manufacturing workflow and consisting of monolithic zirconia with a connector cross-sectional area of 16 mm 2 , offered adequate resistance to chewing loads and still provided satisfactory esthetics at a 2-year follow-up examination., Competing Interests: No conflicts of interest reported.

Dental implants with long-term success of osseointegration have always been the goal, however, difficulties exist. The accumulation of fretting damage at the implant-bone interface often gets overlooked. Commonly used titanium is approximately 7-fold harder and stiffer than cortical bone. Stress shielding caused by the mismatching of the elastic modulus aggravates fretting at the interface, which is accompanied by the risk of the formation of proinflammatory metal debris and implant loosening. Thus, the authors explore functionalized cortical bone-inspired composites (FCBIC) with a hierarchical structure at multiple scales, that exhibit good mechanical and biological adaptivity with cortical bone. The design is inspired by nature, combining brittle minerals with organic molecules to maintain machinability, which helps to acquire excellent energy-dissipating capability. It therefore has the comparable hardness and elastic modulus, strength, and elastic-plastic deformation to cortical bone. Meanwhile, this cortical bone analogy exhibits excellent osteoinduction and osseointegration abilities. These two properties also facilitate each other to resist fretting wear, and therefore improve the success rate of implantation. Based on these results, the biological-mechanical co-operation coefficient is proposed to describe the coupling between these two factors for designing the optimized dental implants., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Objective: To histologically evaluate soft tissue healing following immediately placed one-piece zirconia implant and grafting a xenograft into the buccal gap., Materials and Methods: The third and fourth premolars (PM3 and PM4) in both quadrants of the mandible of nine dogs were used for this experiment. Those teeth were removed flapless and implants were placed into the distal sockets in a lingual position. In one side of the jaw, the gap between the implant and the socket walls was grafted (test) while no grafting was performed in the contralateral side (control), randomly selected. After 6 months of healing, biopsies were obtained and prepared for histological analysis. Soft tissue measures like supracrestal soft tissue height (STH), length of barrier epithelium (BE), and connective tissue (CTC) were measured at buccal and lingual surfaces., Results: The marginal mucosa was in a coronal position on the test side compared with the control side. At the buccal surface, the BE was longer in the test side than in the control side, while the CTC was longer in the control side than in the test side. For the STH (BE + CTC), the difference between the groups was not statistically significant., Conclusion: The placement of a xenograft into the gap between a 1-piece zirconia implant and the buccal wall in dogs modified the process of soft tissue healing, providing less soft tissue recession. The gap size seems to have a modifying effect on the application of this protocol., (© 2023 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

Article Title and Bibliographic Information: Delucchi, F.; De Giovanni, E.; Pesce, P.; Bagnasco, F.; Pera, F.; Baldi, D.; Menini, M. Framework Materials for Full-Arch Implant-Supported Rehabilitations: A Systematic Review of Clinical Studies. Materials 2021, 14, 3251. https:// doi.org/10.3390/ma14123251 SOURCE OF FUNDING: This research received no funding., Type of Study/design: Systematic Review (SR)., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The purpose of this study was to evaluate the osseointegration of zirconia and titanium implants in the rat maxilla in specimens under systemic antiresorptive therapy., Materials and Methods: After 4 weeks of systematic medication administration (either zoledronic acid or alendronic acid), 54 rats received one zirconia and one titanium implants that were immediately inserted in the rat maxilla after tooth extraction. Twelve weeks after implant placement, histopathological samples were evaluated for implant osteointegration parameters., Results: The bone-implant-contact (BIC) ratio revealed no significant inter-group or inter-material differences. The distance between the implant shoulder to the bone level was significantly greater around the titanium implants of the zoledronic acid group compared to the zirconia implants of the control group (p = 0.0005). On average, signs of new bone formation could be detected in all groups, although often without statistical differences. Signs of bone necrosis were only detected around the zirconia implants of the control group (p < 0.05)., Conclusions: At the 3-month follow-up, no implant material was demonstrably better than the others in terms of osseointegration metrics under systemic antiresorptive therapy. Further studies are necessary to determine whether there are differences in the osseointegration behavior of the different materials., (© 2023. The Author(s).)

Introduction: The purpose of this systematic review is to determine if the zirconia implants present better clinical results when compared to titanium implants., Methods: Searches were conducted in 5 databases including, until March 2022, by 2 independent reviewers, according to the inclusion and exclusion criteria established in the study and according whit this question: Do zirconia dental implants present better clinical results than titanium dental implants?, Results: 3235 studies were initially found in the researched databases. 03 randomized clinical trials were included in this systematic review and meta-analysis. A total of 71 patients with 192 implants (87 titanium and 105 zirconia) were evaluated, showing an effectiveness of 87,4% and 78,1% respectively and there was no statistically significant difference in terms of survival rate in the meta-analysis (P = 0.70; I 2  = 0%). Still in the meta-analysis, there was no statistically significant difference between titanium and zirconia implants in relation to the pink esthetich score or bleeding on probing, however, a favorable difference was observed for titanium in relation to marginal bone loss (P = 0.001; I 2  = 0%). None of the studies evaluated had a low risk of bias., Conclusion: Oral rehabilitation with zirconia implants showed no advantages over titanium in this systematic review. However, the small number of studies included and the uncertain risk of bias may raise doubts in this interpretation and the results should be analyzed with caution. New studies with greater methodological rigor, follow-up time and number of interventions should be performed in order to safely determine the indication for the use of zirconia implants., Competing Interests: Declaration of Competing Interest None of the authors of the manuscript has any conflict of interest related to this study., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Objective: To investigate the fracture strength and potential phase transformation of an injection-molded two-piece zirconia implant restored with a zirconia abutment after loading and/or aging., Methods: Thirty-two two-piece zirconia implants (4.0 mm diameter) restored with zirconia abutments were embedded according to ISO 14801 and divided into four groups (n = 8/group): Three groups were either exclusively hydrothermally treated (group HT; 85°C), dynamically loaded (group DL; 10 7  cycles; 98 N), or subjected to both treatments simultaneously (group DL/HT). One group remained untreated (group 0). A sample from each group was cross-sectioned and examined by scanning electron microscopy for possible crystal phase transformation. The remaining samples were then loaded to fracture in a static loading test. A one-way ANOVA was used for statistical analyses., Results: During dynamic loading, three implants of group DL and six implants of group DL/HT fractured at a load of 98 N. The fracture strength of group DL/HT (108 ± 141 Ncm) was significantly reduced compared to the other groups (group 0: 342 ± 36 Ncm; HT: 363 ± 49 Ncm; DL: 264 ± 198 Ncm) (p < .05). Fractures from group 0 and HT occurred at both implant and abutment level, whereas implants from group DL and DL/HT fractured only at implant level. A shallow monoclinic transformation zone of approximately 2 μm was observed following hydrothermal treatment., Conclusions: Within the limitations of this study, it can be concluded that dynamic loading and the combination of loading and aging reduced the fracture strength of the implant abutment combination. Hydrothermal treatment caused a shallow transformation zone which had no influence on the fracture strength., (© 2022 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

The formation of biofilms on the surface of dental implants and abutment materials may lead to peri-implantitis and subsequent implant failure. Recently, innovative materials such as polyether-ether-ketone (PEEK) and its modifications have been used as abutment materials. However, there is limited knowledge on microbial adhesion to PEEK materials. The aim of this in vivo study was to investigate biofilm formation on the surface of conventional (titanium and zirconia) and PEEK implant abutment materials. Split specimens of titanium, zirconia, PEEK, and modified PEEK (PEEK-BioHPP) were manufactured, mounted in individual removable acrylic upper jaw splints, and worn by 20 healthy volunteers for 24 h. The surface roughness was determined using widefield confocal microscopy. Biofilm accumulation was investigated by fluorescence microscopy and quantified by imaging software. The surface roughness of the investigated materials was <0.2 µm and showed no significant differences between the materials. Zirconia showed the lowest biofilm formation, followed by titanium, PEEK, and PEEK-BioHPP. Differences were significant (p < 0.001) between the investigated materials, except for the polyether-ether-ketones. Generally, biofilm formation was significantly higher (p < 0.05) in the posterior region of the oral cavity than in the anterior region. The results of the present study show a material-dependent susceptibility to biofilm formation. The risk of developing peri-implantitis may be reduced by a specific choice of abutment material.

Objective: To assess the clinical outcome of three esthetic implant-supported crown systems fabricated with semi-digital workflow and their influence on the clinical outcome of dental implants., Material and Methods: A total of 30 participants had received dental implants restoring missing maxillary first/second premolars. After 6 weeks, customized zirconia abutments were early loaded. Two months later, the definitive crowns were fabricated using semi-digital workflow and cemented. According to the crown material, 3 groups were randomly allocated; group (Z): ultrahigh-translucent monolithic zirconia, group (C): resin-matrix ceramic and group (P): polyetherketoneketone veneered with light-cured composite resin. Clinical outcomes including the survival and success rates were evaluated at baseline, 6, 12, 18, and 24 months., Results: The survival rate for all studied groups was 100%, while their success rate was 100% for group (Z) and 90% for group (C) and group (P). Based on the functional implant prosthodontic score, a statistically significant difference was detected between group (Z) and group (P) (p < 0.001) as well as between group (C) and group (P) (p = 0.01)., Conclusions: The zirconia group had the most favorable clinical behavior, while the polyetherketoneketone had the least. All crown systems had comparable success rates with similar values of the peri-implant marginal bone loss., Clinical Significance: Using semi-digital workflow, ultrahigh-translucent monolithic zirconia, resin-matrix ceramic and polyetherketoneketone veneered with light-cured composite resin can be considered as favorable implant-supported crowns. The implant-supported crown system based on polyetherketoneketone veneered with light-cured composite resin is counted as a promising esthetic and restorative option., (© 2022 Wiley Periodicals LLC.)

This clinical study evaluated the survival of monolithic lithium disilicate (ML) (IPS Emax, Ivoclar Vivadent) restorations bonded to complete-arch CAD/CAM made titanium or zirconia frameworks. Between August 2007 and December 2009, 15 patients (7 female, 8 male; mean age: 56.8 years old) received 30 implant-supported screw-retained rehabilitations with ML restorations cemented to CAD/CAM made titanium (T) (n=6) or zirconia (Z) frameworks (n=24) adhesively (Multilink Automix, RelyX Unicem) and followed up until December 2015. The evaluation protocol involved technical failures (chipping, debonding or fracture of crown/framework, screw loosening), Californian Dental Association (CDA) quality criteria (Romeo: Excellent; Sierra: Acceptable; Tango: Retrievable; Victor: Not acceptable) and biological failures (mucositis, peri-implantitis). Mean observation time was 60.3 months. No implants were lost, and all the prostheses were in situ. Four mechanical failures occurred in the form of minor chipping (n=3 in ML-Z, n=1 in ML-T) and major fracture in ML crown (n=1 in ML-Z). Romeo scores (N=370) decreased until final observation (N=347) and 23 Sierra scores were given to the restorations. Mucositis was observed in 3 patients and peri-implantitis in one patient. Complete-arch implant-borne FDPs made of monolithic lithium disilicate bonded to titanium or zirconia frameworks could be a promising alternative., (Copyright© 2022 Dennis Barber Ltd.)

Background: To evaluate the clinical and radiographic assessment of customized fusion-sputtered one-piece zirconia implants., Methods: Twenty-eight patients received either fusion sputtered one-piece zirconia implants (n = 14) or one-piece titanium implants (n = 14). All implants were one-piece designs. After 4 months of immediate loading, all implants were restored with a monolithic zirconia crown. All implants were evaluated at baseline, 6 months, 1 year, 2 years, and 5 years. Implant mobility, plaque index, and gingival index evaluations were performed. The measurements of marginal bone level were calculated radiographically., Results: All implants were well maintained through the evaluation period with a 100% survival rate without any clinical complications. Regarding gingival index, there was no statistically significant difference (P = .364) between zirconia (3.3 ± 0.7 mm) and titanium (3.5 ± 0.6 mm) implants, after 5 years. There was no statistically significant difference (P = .470) between zirconia (1.77 ± 0.039 mm) and titanium (1.80 ± 0.28 mm) implants regarding marginal bone loss, after 5 years., Conclusions: One-piece fusion-sputtered zirconia implant represents a reliable treatment modality in replacing a missing tooth in the esthetic zone., (© 2022. The Author(s).)

Purpose: Based on the excellent long-term data, dental implants made of titanium are considered the international implantological standard for replacing missing teeth. However, ceramic implants made of zirconia (ZrO 2 ) have experienced a renaissance in the last 15 years due to constant innovations in materials and products, with material properties and soft tissue- and osseointegration behavior comparable to those of titanium. However, one limitation concerning ceramic implants is the lack of reliable long-term data, especially in the case of two-piece implant systems. As there is an increasing demand for ceramic implants from practitioners and patients, the German Society for Implantology (DGI) has decided to develop a guideline on the use of dental ceramic implants at the highest available evidence level with the involvement of experts in this field., Methods: Statements and recommendations were prepared after conducting a systematic literature search and an independent assessment process involving the relevant clinical literature from 2008 to 2021. The adopted recommendations and statements are summarized in this guideline., Results and Conclusions: It confirms the feasible use of one-piece zirconia implants as an addendum/alternative to titanium implants. No final conclusion regarding the application of two-piece ceramic implant systems could be drawn on the basis of the existing data, thus its use can only be recommended after the patient has been informed in detail about the lack of long-term clinical data., (© 2022. The Author(s).)

Dental implants need to combine mechanical strength with promoted osseointegration. Currently used subtractive manufacturing techniques require a multi-step process to obtain a rough surface topography that stimulates osseointegration. Advantageously, additive manufacturing (AM) enables direct implant shaping with unique geometries and surface topographies. In this study, zirconia implants with integrated lamellar surface topography were additively manufactured by nano-particle ink-jetting. The ISO-14801 fracture load of as-sintered implants (516±39 N) resisted fatigue in 5-55 °C water thermo-cycling (631±134 N). Remarkably, simultaneous mechanical fatigue and hydrothermal aging at 90 °C significantly increased the implant strength to 909±280 N due to compressive stress generated at the seamless transition of the 30-40 µm thick, rough and porous surface layer to the dense implant core. This unique surface structure induced an elongated osteoblast morphology with uniform cell orientation and allowed for osteoblast proliferation, long-term attachment and matrix mineralization. In conclusion, the developed AM zirconia implants not only provided high long-term mechanical resistance thanks to the dense core along with compressive stress induced at the transition zone, but also generated a favorable osteoblast response owing to the integrated directional surface pores. STATEMENT OF SIGNIFICANCE: Zirconia ceramics are becoming the material of choice for metal-free dental implants, however significant efforts are required to obtain a rough/porous surface for enhanced osseointegration, along with the risk of surface delamination and/or microstructure variation. In this study, we addressed the challenge by additively manufacturing implants that seamlessly combine dense core with a porous surface layer. For the first time, a unique surface with a directional lamellar pore morphology was additively obtained. This AM implant also provided strength as strong as conventionally manufactured zirconia implants before and after long-term fatigue. Favorable osteoblast response was proved by in-vitro cell investigation. This work demonstrated the opportunity to AM fabricate novel ceramic implants that can simultaneously meet the mechanical and biological functionality requirements., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2022. Published by Elsevier Ltd.)

Background: This research aimed to explore feasibility and the time required when erbium-doped yttrium aluminum garnet (Er:YAG) laser as a non-invasive treatment modality to retrieve different thicknesses of zirconia material bonded by two dental cements from titanium implant abutments., Methods: Prepared 80 titanium blocks (length: 20 mm, width: 10 mm, height: 10 mm) and square zirconia sheets (length: 10 mm) with different thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) were 20 pieces each. Resin modified glass ionomer cement (RelyX Luting 2; RXL) and resin cement (Clearfil SA luting; CSL) were used to bond zirconia sheet and titanium block. Specimens were kept in 100% humidity for 48 h. Er:YAG laser was used to retrieve the zirconia sheet and recorded the time. Universal testing machine was used to measure the residual adhesion of the samples that did not retrieve after 5 min of laser irradiation. Shear bond strength (MPa) and the time data (s) were analyzed using Kruskal-Wallis Test. The bonding surface and the irradiation surface of the zirconia sheet was examined with the scanning electron microscopy (SEM)., Results: Within 5 min of laser irradiation, RXL group: 1 mm group all fell off, 2 mm group had 3 specimens did not fall off, there was no statistical difference in the average time between the two groups; CSL group: half of the 1 mm group fell off. Shear bond strength test results: there was no statistical difference between 1 and 2 mm in RXL group and 1 mm in CSL group, there was no statistical difference between 3 mm in RXL group and 2 mm in CSL group, and there were significant differences statistically in comparison between any two groups in the rest. SEM inspection showed that the bonding surface and the irradiation surface of the zirconia sheet had changes., Conclusion: In this vitro study, the following could be concluded: it is faster to remove zirconia crowns with thickness less than 2 mm from titanium abutment when luted with RelyX Luting 2 compared to Clearfil SA luting., (© 2022. The Author(s).)

Purpose: To evaluate the clinical performance of zirconia bars with distal extensions supporting mandibular implant overdentures based on biological and prosthodontic outcomes., Materials and Methods: Fifteen edentulous patients (seven women and eight men) were included in a pilot study. Each patient received two interforaminal implants and a mandibular implant overdenture supported by a CAD/CAM zirconia bar with distal extensions, giving a total of 30 implants. The bar design, biological outcomes (implant survival and peri-implant conditions), peri-implant bone level changes recorded on a panoramic radiograph and prosthodontic maintenance (bar fracture and maintenance of the attachment system) were assessed at a 1-year follow-up., Results: After 1 year, all 15 zirconia bars with their corresponding prostheses and implants were successfully in situ with no prosthodontic maintenance required and no biological complications. One patient showed moderate mucosal hyperplasia around the bar. The peri-implant radiographic measurements revealed a stable marginal bone level, with a mean of 0.20 ± 0.67 mm. The mean total length of the bar segments was 41.9 mm (range 35.0 to 51.0 mm), 8.6 mm (range 7.2 to 10.6 mm) of which came from the length of the distal extension, resulting in a mean increase in rigid support of 71% (range 60% to 99%). The mean distal bar connector area was 9.7 mm2 (range 6.8 to 18.7 mm2)., Conclusion: Zirconia bars with distal extensions for implant overdentures appear to be a reliable option for the prosthodontic rehabilitation of edentulous mandibles. A survival rate of 100% was observed for implants, bars and prostheses, with stable peri-implant bone levels, no biological complications and a low risk of prosthodontic maintenance being required.

Objectives: This study aimed to investigate human osteoblasts (HOB) response towards different dental implant abutment materials., Methods: Five dental implant abutment materials were investigated: (1) titanium (Ti), (2) titanium coated nitride (TiN), (3) cobalt chromium (CoCr), (4) zirconia (ZrO₂), and (5) modified polyether ether ketone (m-PEEK). HOBs were cultured, expanded, and seeded according to the supplier's protocol (PromoCell, UK). Cell proliferation and cytotoxicity were evaluated at days 1, 3, 5, and 10 using Alamar Blue (alamarBlue) and lactate dehydrogenase (LDH) colorimetric assays. Data were analysed via two-way ANOVA, one-way ANOVA and Tukey's post hoc test (significance was determined as p < 0.05 for all tests)., Results: All the investigated materials showed high and comparable initial proliferation activities apart from ZrO₂ (46.92%), with P% of 79.91%, 68.77%, 73.20%, and 65.46% for Ti, TiN, CoCr, and m-PEEK, respectively. At day 10, all materials exhibited comparable and lower P% than day 1 apart from TiN (70.90%) with P% of 30.22%, 40.64%, 37.27%, and 50.65% for Ti, CoCr, ZrO₂, and m-PEEK, respectively. The cytotoxic effect of the investigated materials was generally low throughout the whole experiment. At day 10, the cytotoxicity % was 7.63%, 0.21%, 13.30%, 5.32%, 8.60% for Ti, TiN, CoCr, ZrO₂, and m-PEEK. The Two-way ANOVA and Tukey's Multiple Comparison Method highlighted significant material and time effects on cell proliferation and cytotoxicity, and a significant interaction (p < 0.0001) between the tested materials. Notably, TiN and m-PEEK showed improved HOB proliferation activity and cytotoxic levels than the other investigated materials. In addition, a non-significant negative correlation between viability and cytotoxicity was found for all tested materials. Ti (p = 0.07), TiN (p = 0.28), CoCr (p = 0.15), ZrO₂ (p = 0.17), and m-PEEK (p = 0.12)., Significance: All the investigated materials showed excellent biocompatibility properties with more promising results for the newly introduced TiN and m-PEEK as alternatives to the traditionally used dental implant and abutment materials., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

The global market for dental implants is constantly evolving. To overcome the limitations of conventional strategies - invasive surgeries and bone loss around the implant-, new approaches, namely the development of CAD/CAM customized implants, are emerging as promising solutions for replacing missing teeth, thus avoiding destruction of bone by drilling it. Despite the efforts that are being carried out, the designing, including image acquisition, and manufacturing efficacy of such rehabilitation therapy is not easily found in the literature. In this sense, this research work aimed to assess the errors associated with the image acquisition, treatment and manufacturing of Customized Root-Analogue Implants (CRAI). The experimental procedure, carried out in a dog cadaveric mandible, encompassed the image acquisition and treatment and the subsequent manufacturing of four different CRAI. Two Image acquisition methods (CBCT and X-ray), and different software for their treatment were used, and the final CRAI were manufactured by Computer Numerical Control. Results revealed the CBCT scan allowed to properly visualize the original teeth contours. However, all the obtained teeth geometries presented smaller surface areas when compared to the original teeth indicating however a systematic predictable error. On the other hand, when comparing the surface area of the digital and the manufactured teeth, very small differences were observed, which indicates that the CNC manufacturing technique is a promising solution for such applications. When placing the produced CRAI in the dog mandible it was possible to observe a lack of congruency between the CRAI and bone, mainly due to image acquisition process errors and the destruction of the periodontal ligament during the soft tissues removal process. Thus, CBCT images seem to be a feasible route to design root-analogue implants, and, if needed, a compensation strategy for the systematic image acquisition error may be implemented., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Purpose: To evaluate, in a minipig model, the soft tissue integration of four different transmucosal materials, as well as the peri-implant bone remodeling., Materials and Methods: A total of 40 implants were placed in five minipigs in a single stage surgery, and two of each of the following abutment materials were used in each animal: (1) titanium (Ti; control), (2) polymethylmethacrylate (PMMA), (3) zirconia (Zi), and (4) veneering ceramic (VC). After a healing period of 3 months, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attachment) were assessed on each abutment and the distance from the implant margin to first bone-to-implant contact (BIC) was measured., Results: The mean biological width-characterized by the sum of junctional epithelium and connective tissue measurements-was 3.8 (0.6) mm and no statistically significant difference was found between the four groups (p = 0.41). However, a long junctional epithelium (3.3-3.8 mm) and a very short connective tissue attachment (0.1-0.2 mm) were observed with all abutments. The measured peri-implant bone remodeling was similar in all four groups (p = 0.88)., Conclusions: Within its limitations, this study showed that all tested materials allowed soft tissue integration, consisting of a long junctional epithelium, extending close to the bone level, and a rather short portion of connective tissue., (© 2022 by the American College of Prosthodontists.)

Background: Implant restoration in the anterior region was a great challenge for dentists. The aim of the study was to use three-dimensional finite element analysis to analyze the feasibility of the fixed partial denture supported by two diverse material implants in the maxillary anterior region, to provide a theoretical basis for clinical therapy., Methods: Based on CBCT data, a three-unit fixed partial denture supported by two endosseous implants with a diameter of 3.5 mm and a length of 10 mm inserted in the upper left central incisor and canine was created. The materials of the implant were verified in seven models. Titanium (Ti), zirconia (Zr) and titanium-zirconia (TiZr) were used for the implant materials. A total load of 150 N was applied on the prosthesis units at 45˚ to the long axis of the abutment., Results: The maximal displacement of the implant was 6.1 µm in the titanium implant at the canine region in the TiZr-Ti model. The stresses in the cortical bone and strains in the spongious bone were below the physiological upper limits. The highest value of the maximal stress in cortical bone was 78 MPa, observed in the left central incisor region of Zr-TiZr model. And the highest value of the maximal strain in the spongious bone was 1738 μstrain around the titanium implant of the Ti-TiZr model., Conclusions: From the biomechanical point of view, fixed partial denture supported by two diverse material implants in the maxillary anterior region is an acceptable treatment option., Competing Interests: Declaration of Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. We state that all authors have viewed and agreed to the submission., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Objectives: This systematic review aimed to assess in vitro studies that evaluated neutrophil interactions with different roughness levels in titanium and zirconia implant surfaces., Material and Methods: An electronic search for literature was conducted on PubMed, Embase, Scopus, and Web of Science and a total of 14 studies were included. Neutrophil responses were assessed based on adhesion, cell number, surface coverage, cell structure, cytokine secretion, reactive oxygen species (ROS) production, neutrophil activation, receptor expression, and neutrophil extracellular traps (NETs) release. The method of assessing the risk of bias was done using the toxicological data reliability assessment tool (TOXRTOOL)., Results: Ten studies have identified a significant increase in neutrophil functions, such as surface coverage, cell adhesion, ROS production, and NETs released when interacting with rough titanium surfaces. Moreover, neutrophil interaction with rough-hydrophilic surfaces seems to produce less proinflammatory cytokines and ROS when compared to naive smooth and rough titanium surfaces. Regarding membrane receptor expression, two studies have reported that the FcγIII receptor (CD16) is responsible for initial neutrophil adhesion to hydrophilic titanium surfaces. Only one study compared neutrophil interaction with titanium alloy and zirconia toughened alumina surfaces and reported no significant differences in neutrophil cell count, activation, receptor expression, and death., Conclusions: There are not enough studies to conclude neutrophil interactions with titanium and zirconia surfaces. However, different topographic modifications such as roughness and hydrophilicity might influence neutrophil interactions with titanium implant surfaces., (© 2022 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

Aim: The aim of this study was to investigate the combined effect of ceramic material, ceramic thickness, and implant abutment background to the final color of restorations., Settings and Design: This was a comparative in vitro study., Materials and Methods: Three different types of monolithic and porcelain-veneered zirconia disc-shaped specimens (Prettau Anterior, VITA YZ ST, and VITA YZ HT) were prepared in A3 shade with two different thicknesses (1 mm and 1.5 mm) (n = 10). Each zirconia material was made of 4-mm thickness as a control specimen of each monolithic zirconia type, and 4-mm thick veneering ceramic (VITA VM9 Base Dentine) was made as a control for veneered zirconia groups. Three simulated implant abutments were fabricated from titanium, white-shaded and yellow-shaded zirconia. The zirconia specimens were placed on different abutment backgrounds, and the color difference (ΔE) between experimental and control specimens was measured., Statistical Analysis Used: The three-way ANOVA and the Scheffé test were used for data analysis (α = 0.05)., Results: The mean ΔE values between two thicknesses were significantly different in every background for all zirconia materials. The ΔE values of zirconia specimens on yellow zirconia were lower than those of other abutments. The clinically acceptable ΔE value (ΔE <3) was found in some monolithic zirconia specimens on white-shaded and yellow-shaded abutments, while the ΔE value is approximately 3 or less in all 1.5-mm thick porcelain-veneered zirconia groups., Conclusions: Different zirconia materials on implant abutments affected the final color of restorations. To achieve satisfactory color, the minimum thickness of zirconia restorations should be at least 1.5 mm on yellow zirconia abutment., Competing Interests: None