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Objectives: This study aimed to assess the vertical misfit at the implant-abutment interface in external and internal connections across various implant brands, comparing original milled titanium abutments with laser-sintered cobalt-chromium (Co-Cr) abutments., Materials and Methods: A total of 160 implants from four different brands were utilized, with 80 featuring external connections (EC) and 80 internal connections (IC). Original milled titanium abutments (n = 160) and Co-Cr laser-sintered abutments (n = 160) were randomly attached to each connection type, following the manufacturer's recommended torque. After undergoing thermal cycling, the vertical misfit was measured using a scanning electron microscope. Statistical analyses were performed using the Kruskal-Wallis and Mann-Whitney U tests. The significance level was set at α = 0.05., Results: The original milled titanium abutments exhibited the lowest misfit values. Significant differences were identified between both abutment types for EC (d = 109.578 μm; p = 0.0001) and IC (d = 44.317 μm; p = 0.002). The EC with laser-sintered abutments demonstrated the highest marginal misfit values, with an average of nearly 30 μm, while a misfit value of 11.382 μm was achieved in the IC. Differences were observed among the brands for milled abutments in both EC and IC. Similarly, variations were also noted for the laser-sintered Co-Cr abutments in EC and IC configurations., Conclusions: The vertical misfit of the original milled titanium abutments in all groups was within the clinically acceptable range for IC. The connection type significantly impacted the vertical misfit in laser-sintered Co-Cr abutments. Differences among the implant systems were observed for both connection types and abutment types evaluated., Clinical Relevance: Using original milled titanium abutments, particularly in internal connection systems, can lead to better fit and stability at the implant-abutment interface, potentially reducing the risk of mechanical complications and improving long-term implant success., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Dental implants are crucial in contemporary oral rehabilitation, necessitating optimal integration with the surrounding soft tissues for durable success. The attachment between the implant surface and peri-implant mucosa should establish a secure seal to prevent bacterial infiltration and subsequent tissue inflammation. This concise review examines the histological and biological perspectives of peri-implant soft tissue reactions to zirconium and titanium abutments, shedding light on their respective advantages and limitations. While titanium has been the gold standard, zirconia has gained attention due to its biocompatibility and aesthetic appeal. Histological studies show comparable soft tissue attachment and inflammatory responses between the two materials. Further research is needed to explore surface treatments and optimize outcomes in dental implant rehabilitation.

Statement of Problem: Osseointegration is now primarily established, but soft tissue integration is still susceptible to failure and problematic on implant surfaces. So, implant dentistry is increasingly focusing on improving peri-implant soft tissue integration., Purpose: The present study aimed to evaluate the blood fibrin clot formation and adhesion on the abutment after cleaning and decontamination and determine the suitable abutment surface associated with fibrin clot attachment., Materials and Methods: Forty-two abutments (14 per group) were used in the present study: a brand-new (BN), contaminated with biofilm (CO) and decontaminated with an enzymatic cleaner and autoclave sterilization (DEC). For a fibrin clot, 9 mL of whole human blood and abutments was centrifuged at 2700 rpm for 12 min. Clots were divided into two parts for histomorphometry and scanning electron microscopy (SEM) analysis. Twelve abutments disconnected from the clot and two not treated with blood were observed under SEM., Results: Residual debris and biofilm were observed on the abutment surface in the CO group but not in other groups. Healthy and organized fibrin clots formed on all abutments. The fibrin extension areas are distributed uniformly in BN and DEC groups but irregularly in CO. The surface percentage of the fibrin clot extensions was 41.76% ± 6.73, 26.99% ± 6.40, and 37.83% ± 9.72 for the BN, CON, and DEC groups, respectively. The blood clot-attached areas in the CO group were statistically lower than the other groups. No difference was observed between the BN and DEC groups., Conclusions: This study confirmed that surface contamination could influence blood clot attachment on the abutment surfaces. Cleaning and sterilization can have a favorable effect on soft tissue healing on abutment surfaces., (© 2024 Wiley Periodicals LLC.)

The peri-implant soft tissue with inferior adhesion takes a long healing period to form, which is undesirable for the reaction around the peri-implant soft tissues. The aim of this study is to improve the physicochemical properties of titanium (Ti) and zirconia (ZrO 2 ) implant abutments and shorten the formation period of periabutment epithelium tissue. A nonthermal atmospheric plasma brush (NTAPB, N) was employed for Ti and ZrO 2 activation. The surface topographies, roughness, crystallinity, wettability, and chemical elements of the abutment materials were examined. The epithelial cell behavior analysis and tissue remodeling of the periabutment epithelial tissue were performed in vitro and in vivo. N-Ti and N-ZrO 2 had a similar good surface wettability, with a 65 and 70% increase in oxygen content and a 70 and 75% decrease in carbon content, respectively. Both N-Ti and N-ZrO 2 showed excellent adhesion, spread, and proliferation of epithelial cells in vitro, with improved adhesion molecule expression levels compared to untreated samples. N-Ti and N-ZrO 2 abutments were placed in the implantation sites of rats. From week 2 to week 6 after implantation, N-Ti and N-ZrO 2 had similar periabutment epithelium tissue formation, and both had increased plectin-positive and laminin γ2-positive cell numbers compared to Ti and ZrO 2 . The NTAPB shows promising abutment modification abilities. It promotes the expression levels of adhesion molecules and the epithelial cell performance, which later leads to a quicker formation and remodeling of the important periabutment epithelial tissue.

Photobiomodulation (PBM) therapy is used to stimulate cell proliferation and metabolism, as well as reduce inflammatory cytokine synthesis, which plays a main role in the long-term stability of implants. This study assessed the response of gingival fibroblasts cultured on titanium (Ti) and zirconia (ZrO 2 ), submitted to PBM and exposed to lipopolysaccharide (LPS). Cells seeded on Ti and ZrO 2 were irradiated (InGaAsP; 780 nm, 25 mW) 3 times, using 0.5, 1.5, and 3.0 J/cm 2 doses, and exposed to Escherichia coli LPS (1 μg/mL). After 24 h, cell viability (alamarBlue, n = 8), interleukin 6 (IL-6) and 8 (IL-8) synthesis (ELISA, n = 6), and IL-6 and vascular endothelial growth factor (VEGF) gene expression (qPCR, n = 5) were assessed and statistically analyzed (one-way ANOVA, α = 0.05). Cell morphology was evaluated by fluorescence microscopy. Increased cell viability occurred in all groups cultured on Ti compared with that of the control, except for cells exposed to LPS. Fibroblasts cultured on ZrO 2 and LPS-exposed exhibited reduced viability. PBM at 3.0 J/cm 2 and 1.5 J/cm 2 downregulated the IL-6 synthesis by fibroblasts seeded on Ti and ZrO 2 , as well as IL-8 synthesis by cells seeded on ZrO 2 . Fibroblasts seeded on both surfaces and LPS-exposed showed increased IL-6 gene expression; however, this activity was downregulated when fibroblasts were irradiated at 3.0 J/cm 2 . Enhanced VEGF gene expression by cells seeded on Ti and laser-irradiated (3.0 J/cm 2 ). Distinct patterns of cytoskeleton occurred in laser-irradiated cells exposed to LPS. Specific parameters of PBM can biomodulate the inflammatory response of fibroblasts seeded on Ti or ZrO 2 and exposed to LPS.

Purpose: To evaluate the long-term implant survival rate of titanium implants with zirconia abutments, and the effects of implants with zirconia abutments on marginal bone loss (MBL) and pocket probing depth (PPD) compared with all-titanium implants., Materials and Methods: The searched electronic database included the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and the Chinese Biomedical Literature Database. Two types of studies were included: clinical studies reporting the survival rate of titanium implants with zirconia abutments with at least a mean/median 5-year follow-up, and clinical trials reporting the effects of implants with zirconia abutments on MBL and PPD compared with all-titanium implants. Two reviewers screened and selected the records, assessed quality, and extracted data of included studies independently., Results: This review included 16 studies from 18 publications. None of the comparative studies was assessed at a low risk of bias. The overall implant survival rate of implants with zirconia abutments was estimated to be 96% (confidence intervals [CIs] [94%, 98%], I 2 = 0%). For the comparison between implants with zirconia abutments and all-titanium implants, the results significantly favored implants with zirconia abutments (for MBL, mean difference [MD] = -0.09, CIs [-0.17, 0.00], p = 0.05, I 2 = 40%; for PPD, MD = -0.18, CIs [-0.32, -0.05], p = 0.008, I 2 = 0%). Zirconia abutments were favored more when the prosthesis was an implant-supported overdenture rather than a single crown., Conclusions: Implants with zirconia abutments may have an acceptable performance on peri-implant health compared with all-titanium implants; however, the implant survival rate of implants with zirconia abutments is slightly lower than all-titanium implants in the long-term follow-up. Additional studies are needed to explain this dichotomy., (© 2019 by the American College of Prosthodontists.)

Background: Improvements of soft tissue to the abutment surface results in more stable peri-implant conditions, however, few human histological studies have compared soft tissue responses around different abutment materials., Purpose: To describe the peri-implant tissue around 3 abutment materials; titanium, zirconia, and gold alloy, over an 8-week healing period., Materials and Methods: Fifteen edentulous sites were treated with implants. Eight weeks later, peri-implant tissue was harvested and processed using a nonseparation resin embedded technique. The tissue attachment characteristics were assessed at clinical stages using the gingival index (GI) score, surgical stage (surgical score), and histological stage (histological attachment percentage). Additionally, the inflammatory responses were evaluated using inflammatory extent and inflammatory cellularity grades. Nonparametrical statistics were used to describe the GI and surgical scores, and analytical statistics were used to analyze the histological attachment percentages as well as the inflammatory extent and cellularity grades amongst the 3 groups., Results: There were no statistically significant differences among the groups for GI score (P = .071) and surgical score (P = .262). Titanium and zirconia exhibited nearly similar mean histological attachment percentages while gold alloy had a significantly lower percentage (P = .004). For the inflammatory extent and cellularity grades, the odds of being one grade higher for gold alloy abutment was 5.18 and 17.8 times that of titanium abutment, respectively. However, for the zirconia abutment, the odds were 0.87 and 7.5 times higher than the titanium group., Conclusions: The tissue around the gold alloy abutments resulted in worse attachment conditions compared with the titanium and zirconia abutments. Inflammation tended to be higher in the tissue around the gold alloy abutments than the titanium and zirconia abutments., (© 2017 Wiley Periodicals, Inc.)

Background: The adhesive connection between titanium base and zirconia coping of two-part abutments may be responsible for the failure rate. A high mechanical stability between both components is essential for the long-term success., Purpose: The aim of the present in-vitro study was to evaluate the influence of different surface modification techniques and resin-based luting agents on the retention forces between titanium and zirconia components in two-part implant abutments., Materials and Methods: A total of 120 abutments with a titanium base bonded to a zirconia coping were investigated. Two different resin-based luting agents (Panavia F 2.0 and RelyX Unicem) and six different surface modifications were used to fix these components, resulting in 12 test groups (n = 10). The surface of the test specimens was mechanically pretreated with aluminium oxide blasting in combination with application of two surface activating primers (Alloy Primer, Clearfil Ceramic Primer) or a tribological conditioning (Rocatec), respectively. All specimens underwent 10,000 thermal cycles between 5°C and 55°C in a moist environment. A pull-off test was then conducted to determine retention forces between the titanium and zirconia components, and statistical analysis was performed (two-way anova). Finally, fracture surfaces were analyzed by light and scanning electron microscopy., Results: No significant differences were found between Panavia F 2.0 and RelyX Unicem. However, the retention forces were significantly influenced by the surface modification technique used (p < 0.001). For both luting agents, the highest retention forces were found when adhesion surfaces of both the titanium bases and the zirconia copings were pretreated with aluminium oxide blasting, and with the application of Clearfil Ceramic Primer., Conclusion: Surface modification techniques crucially influence the retention forces between titanium and zirconia components in two-part implant abutments. All adhesion surfaces should be pretreated by sandblasting. Moreover, a phosphate-based primer serves to enhance long-term retention of the components., (© 2015 Wiley Periodicals, Inc.)

Background: Microleakage through the interface has been documented in implant systems with titanium (Ti) abutments. There is a current increase in the use of zirconia (Zi) abutments especially in esthetic zone in where higher risk of visible metal color through the peri-implant tissues exists., Purpose: The aim of the present in vitro study is to evaluate the leakage at the implant fixture-abutment interface with two different screw-retained abutment systems at different torque values in a nonloading condition., Materials and Methods: In vitro study design included four groups (Ti and Zi torqued at 25 and 15 Ncm [N = 8/group]). Microcomputed tomography (micro-CT) was chosen to detect microgap. Microleakage from the implant chamber to the external milieu was evaluated using limulus amebocyte lysate (LAL) test, while microleakage from external milieu to the implant chamber was evaluated using toluidine blue dye (TBD) and colorimeter., Results: Micro-CT images did not reveal any microgap. LAL test showed that there is a time-, abutment-, and torque-dependent increase in microleakage (p = .001) with Zi torqued at 15 Ncm having higher leakage with time compared with Ti torqued at 15 Ncm (p = .002), as well as Zi torqued at 15 Ncm having higher leakage with time compared with Zi torqued at 25 Ncm (p = .01). TBD test showed a nonsignificant increase in microleakage with higher leakage related to titanium abutment groups (p > .05). Repeated torque/antitorque handling differentially affected microleakage (p = .01)., Conclusions: Within the limits of this study, there is a statistically significant difference in bidirectional microleakage with time, abutment type, and torque values being major players for leakage from internal implant chamber to external milieu, while the abutment type and time but not the torque value being important factors for leakage from external milieu into implant chamber in nonloading condition. Future studies are needed to determine peri-implant health around Zi abutments., (© 2015 Wiley Periodicals, Inc.)

Purpose: To evaluate hard and soft tissue response and mechanical integrity for screw-retained layered zirconia crowns bonded to titanium nitride-coated titanium (TiN) CAD/CAM abutments supported by implants at 1- and 2-year followups. Materials and Methods: A total of 46 patients were restored with a total of 102 free-standing implant-supported layered zirconia crowns, which were bonded to their respective abutments in the dental laboratory and delivered as a one-piece screw-retained crown. Baseline, 1-year, and 2-year data were collated on pocket probing depth, bleeding on probing, marginal bone levels, and mechanical complications. Results: Of the 46 patients, 4 patients with one implant each were not followed-up. These patients were not included in the analysis. Of the remaining 98 implants, due to failed appointments during the global pandemic, soft tissue measurements were recorded for 94 implants at year 1 and 86 implants at year 2, with a mean buccal/lingual pocket probing depth of 1.80/1.95 mm and 2.09/2.17 mm, respectively. Mean bleeding on probing was 0.50 and 0.53 at 1 and 2 years, which represents somewhere between no bleeding and a spot bleed according to the study protocol. Radiographic data were available for 74 implants at year 1 and 86 implants at year 2. The mean marginal bone change from baseline was +0.11 mm mesially and +0.19 mm distally at 1 year and +0.24 mm mesially and +0.16 mm distally at 2 years. The final bone level with respect to the reference point was +0.49 mm mesially and +0.19 mm distally at the end of the study period. Mechanical complications involving a slight misfit of the crown margin were recorded for one unit (1%), porcelain fracture for 16 units (16%), and a loss of preload for 12 units (12%) of < 5 Ncm (< 20% of initial preload). Conclusion: The biologic and mechanical stability of ceramic crowns bonded to CAD/CAM screw-retained abutments using angulated screw access was considered to be high, with overall bone gain, excellent soft tissue health, and only limited mechanical complications related to generally small fractures of the porcelain and a clinically insignificant loss of preload. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the formed biofilm on two types of implant surfaces (hydrophilic or hydrophobic) associated with titanium (Ti) or zirconia (Zn) abutments. Materials and Methods: Samples were separated into four groups according to type of surface and abutment used (n = 10): (1) hydrophobic/Ti abutment, (2) hydrophilic/Ti abutment, (3) hydrophobic/Zn abutment, and (4) hydrophilic/Zn abutment. Implant-abutment assemblies were incubated with human saliva and supragingival biofilm. Samples of biofilm were evaluated by DNA Checkerboard hybridization, identifying up to 41 species. Scanning electron microscopy (SEM) images were obtained from the implants and abutments. Results: The microbial count was higher for samples from groups with the hydrophilic/Ti abutment, followed by hydrophobic/Zn abutment, hydrophilic/Ti abutment, and hydrophobic/Zn abutment (P < .05). Hydrophilic surfaces and Zn abutments showed the highest counts of microorganisms. Individual bacterial counts were variable between groups; the hydrophilic/Zn abutment group had the highest microbial diversity, including T forsythia, P nigrescens, S oralis, S sanguinis, L casei, M orale, P aeruginosa, P endodontalis, S aureus, S gallolyticus, S mutans, S parasanguinis, S pneumoniae, and C albicans. The hydrophilic/Ti abutment group had the highest count of T forsythia and T denticola, microorganisms of Socransky red complex. The SEM images showed the bacterial colonization in both surfaces of the implant and abutment. Conclusion: Different surfaces of implants and abutments showed significant differences in the count and diversity of species. The hydrophilic/Zn abutment group presented the highest count and diversity of target species. [ABSTRACT FROM AUTHOR]

This article focuses on preclinical studies and reviews the available evidence from the literature on dental implant and abutment materials in the last decade. Specifically, different peri-implantitis materials and how surface modifications may affect the peri-implant soft-tissue seal and subsequently delay or hinder peri-implantitis are examined. This review analyzed more than 30 studies that were Randomized Controlled Trials (RCTs), Controlled Clinical Trials (CCTs), or prospective case series (CS) with at least six months of follow-up. Meta-analyses were performed to make a comparison between different implant materials (titanium vs. zirconia), including impact on bone changes, probing depth, plaque levels, and peri-implant mucosal inflammation, as well as how the properties of the implant material and surface modifications would affect the peri-implant soft-tissue seal and peri-implant health conditions. However, there was no clear evidence regarding whether titanium is better than other implant materials. Clinical evidence suggests no difference between different implant materials in peri-implant bone stability. The metal analysis offered a statistically significant advantage of zirconia implants over titanium regarding developing a favorable response to the alveolar bone. [ABSTRACT FROM AUTHOR]

• Dynamical loading on dental implants generates particle production and wear. • Large particles are trapped inside the internal connection. • Particle size is affected by implant and abutment material. • Stiffness of the complex is related to type of abutment material. • Low level ion release/leakage is seen during corrosion tests. Particle generation from implant components caused by frictional wear affect the surrounding peri-implant tissues. The objective of this study was to evaluate the effect of combining implant and abutment materials on wear and particle release in a dynamical loading setup. A customized dynamical loading machine was used to subject two implant materials (Titanium and Titanium- Zirconium alloy) paired with two different abutment materials (Titanium and Zirconia) to a cyclic loading set of 240.000 cycles (simulating 1 year of clinical use). The implant and abutment complex was immersed in corrosive liquid to collect particle debris and measure the release of corroded ions. Scanning electron microscopy was used to analyze signs of wear on the components after testing and evaluate the size and composition of particle debris. Wear signs were evident in all material couplings. Particle debris was found on top, inside the implants, and on the abutment heads. The particle size ranged between 0.6 and 16.9 µm, with larger particles composed of Ti. Smaller-sized particles were found in the container liquid ranging from 0.253 to 1.7 µm compared to inside the implants ranging from 3.25 to 95.3 µm. Larger particles were found inside Tizr implants compared to Ti implants. Low levels of ions released due to corrosion were found when measuring content in surrounding liquid. Particle generation is evident when subjecting dental implant and abutment couplings in a dynamic loading setup. Internally connected implants hinder the release of larger particles to surrounding container liquid. [ABSTRACT FROM AUTHOR]

Purpose: This study was conducted to analyze how a cleaning treatment using plasma of argon would affect fibroblast growth on titanium disks at different time points to determine whether this treatment could enhance soft tissue healing around titanium dental implant abutments. Materials and Methods: Sixty sterile disks made of machined grade 5 titanium were divided into two groups; 30 disks were left untreated (control) and 30 were cleaned using plasma of argon (test). To simulate clinical conditions during soft tissue healing around titanium abutments, both groups were immersed in a culture of murine fibroblasts (L929) for 2, 8, or 48 hours. After preparation, they were stained using 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) to label the cellular nuclei and fluorescent phalloidin to label the cellular bodies. The nuclei were counted, and cellular bodies were analyzed with fluorescent microscopy and imaging analysis software. Analysis was performed at the three different time points. Results: Fibroblast adhesion for the test group was statistically significantly greater versus the control group at 2 and 8 hours but not at 48 hours. At 2 and 8 hours, the cellular bodies in the test group appeared flatter and more spread out, revealing more advanced cellular adhesion, compared to the cells observed in the control group. At 48 hours, the test and control specimens were nearly indistinguishable. Conclusion: The removal of organic and inorganic contaminants from the surfaces of titanium disks using plasma of argon accelerated fibroblast adhesion in the early stages of colonization (2 to 8 hours). This effect disappeared after 48 hours as a result of saturation. Clinically, abutment cleaning using plasma of argon might positively affect soft tissue healing in early stages. [ABSTRACT FROM AUTHOR]

Purpose: Misfit of implant components has been linked to restorative complications such as screw loosening. Although previous studies have shown a correlation between rotational misfit and screw loosening, the impact of casting procedures on rotational misfit is lacking. The aim of this in vitro study was to evaluate the effect of casting procedures on rotational misfit of cast abutments when compared to machined titanium abutments. Materials and Methods: Forty-eight external hexagonal implants and 48 abutments were placed in 4 groups of 12 samples each: (1) machined titanium abutments, (2) premachined palladium abutments cast-on with palladium, (3) plastic burnout abutments cast with nickel chromium, and (4) plastic burnout abutments cast with cobalt chromium. Rotational misfit between the external hexagon of the implant and the internal hexagon of the abutment was measured using standardized techniques and recorded in degrees. Mean values for each group were analyzed with analysis of variance and Tukey test. Results: The mean rotational misfit was 1.21 ± 0.57 degrees for machined titanium abutments, 1.77 ± 130 degrees for cast-on abutments, 1.98 ± 0.72 degrees for cast NiCr abutments, and 2.79 ± 1.13 degrees for cast CoCr abutments. Significantly greater rotational misfit was recorded with cast CoCr abutments when compared to machined titanium abutments (P < .05). Conclusion: Rotational misfit was less than 2 degrees for all groups except for cast CoCr abutments, which demonstrated a significantly greater rotational misfit. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess the precision at the implant interface of titanium, zirconia, and alumina Procera abutments with a hexagonal connection for single-tooth restorations. Materials and Methods: Twenty Procera abutments were produced with commercially pure titanium, 20 with zirconia, and 20 with alumina using computer-assisted design and manufacture (CAD/CAM). The rotational freedom of the abutments was assessed to detect the precision of fit of each abutment on the top of the implant hexagon. Results: Significant differences relative to rotational freedom were found between groups: the titanium group and the zirconia group did not differ significantly, but both demonstrated significantly smaller mean rotational freedoms than the alumina group (P < .05). Rotational freedom was less than 3 degrees for all abutments. Conclusions: The hexagonal misfit of the Procera abutment on the implant hexagon may be implicated in screw joint loosening. In the present study, all types of CAD/CAM Procera abutments consistently showed less than 3 degrees of rotational freedom in a situation where the abutment was connected to an implant by a hexagonal external connection. [ABSTRACT FROM AUTHOR]

The main goal of this review is to provide an in-depth description of published work on the application of zirconia for dental implansts and restorations on titanium implants, with an emphasis on clinical studies from the past dozen years with at least 1-year follow-up. Online databases (Pubmed, Science Direct, Web of Science) were consulted on this topic. Published work from 2007 to 2019 was collected, analyzed and pertinent articles were selected for inclusion on this review. No clear superiority has been documented in biocompatibility, osteoconductivity, physical properties or allergenicity with zirconia implants compared to titanium, notwithstanding an esthetic benefit. While short-term studies have been promising, larger multicentered, longitudinal and randomized clinical trials with success data are required to validate zirconia as a viable alternative to the titanium implant and its design. Zirconia abutments with a titanium base have revealed a high survival rate and show no difference to metal. Bi-layered zirconia ceramic restorations are a valid treatment alternative to metal ceramic implant restorations for single crowns with similar biological complications and enhanced esthetics. Monolithic zirconia restorations hold promise to address the chipping incidence of the bi-layered ceramic restoration, but longer-term studies are necessary, and work needs to be done to improve their esthetics. The gingival feldspathic porcelain veneered monolithic zirconia complete arch prosthesis versus a resin metal prosthesis, in medium-term studies, offers a high survival rate and low mechanical complication rate, reduced laboratory costs, superior durability and wear characteristics, enhanced fit due to digital fabrication, availability of a digital file for duplication in the future, acrylic try-for adjustment and approval, and reduced plaque and biofilm accumulation. Zirconia is a versatile material for implant prosthodontic application. Longer-term multi-centered studies are needed to assess success criteria and patient-related outcomes measurements. Monolithic zirconia offers enhanced mechanical properties for implant restorations, but development is needed to optimize esthetics. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this laboratory study was to evaluate the fatigue resistance, fracture resistance and mode of failure of posterior hybrid‐abutment‐crown vs. hybrid‐abutment with separate crown, both bonded to short titanium bases. Materials and Methods: Thirty‐two titanium implants were embedded perpendicularly in auto‐polymerizing resin. Implant‐supported restorations simulating a maxillary first premolar were designed and milled using a CAD/CAM system and divided into 2 groups according to material (n = 16): zirconia (Z) and lithium disilicate (L). Each group was subdivided into two subgroups according to design (n = 8): hybrid‐abutment‐crown (ZS, LS) and hybrid‐abutment with separate crown (ZC, LC). Each group was subjected to 1.2 million cycles of thermo‐mechanical fatigue loading in a dual‐axis chewing simulator at 120 N load. Surviving specimens were subjected to quasi‐static loading in a universal testing machine. Mode of failure was determined under a low magnification optical microscope. Results: During chewing simulation, 18.8% of zirconia and 43.8% of lithium disilicate restorations failed. The fracture resistance median values ranged from 3,730 N for group ZC, 3,400 N for group ZS, 1,295 N for group LS to 849 N for group LC. Group ZC had a statistically significant higher fracture resistance than groups LC and LS; however, it did not differ significantly from group ZS (p ≤ 0.05). Failures were seen in both titanium bases and ceramic superstructure. Conclusions: Zirconia and lithium disilicate hybrid implant‐supported restorations with short (3 mm) titanium bases failed in a considerable number already during chewing simulation. Therefore, despite their high fracture strength the use in the posterior region should be considered critically. [ABSTRACT FROM AUTHOR]

Background Studies have reported an increased risk for fractures of zirconia abutments compared with titanium abutments. Purpose The aim of this study was to evaluate single-tooth implant restorations with one-piece yttria-stabilized internal zirconia abutments on narrow and regular diameter implants up to 6 years after insertion. Material and methods This study comprises 52 consecutively treated patients, with a median age of 19 years. In total, 59 narrow (3.3 mm) and 10 regular (4.1 mm) diameter implants were installed. Sixty-five all-ceramic crowns were cemented on implant-supported one-piece internal zirconia abutments and 4 restorations were screw-retained. Results Thirty-five patients with 48 implant restorations participated in the final examination and another 14 patients with 16 implant restorations were possible to reach and could be interviewed. The implant survival was 100% but the survival rate for the implant-supported ceramic restorations was lower, 87.5%. Three crowns (4.7%) were remade for different reasons. Five restorations (7.8%) were remade due to fracture of the internal one-piece zirconia abutment. Four of these fractures occurred in 3.3 mm implant abutments. Conclusions Narrow diameter implants offer an opportunity to restore small single-tooth edentulous gaps. For esthetical reasons the choice of an abutment in zirconia can be favorable, but at least with the used implant system, there seems to be an increased risk for fracture. Most patients were very satisfied with the esthetics and function of their implant restorations. [ABSTRACT FROM AUTHOR]

Background Reuse or 'recycle' of dental implant healing abutments in clinical practice is common, primarily for economic rational. Purpose To determine of this practice results in reuse of components that carry with them some degree of contamination between patients, even following thorough cleaning and sterilization. Materials and Methods One hundred healing abutments were collected from eight clinicians following patient use. The abutments were cleaned, sterilized, and then collected. The samples were treated with a protein specific stain (Phloxine B), and photographed. Results Ninety-nine percent of the abutments showed protein contamination at one or more sites following cleaning and sterilization. Conclusion Reuse of healing abutments between patients should be reevaluated in light of this data. [ABSTRACT FROM AUTHOR]

Background Few studies have examined epithelial attachment to zirconia and the proliferative ability of epithelial cells on zirconia surfaces. Purpose To evaluate the adhesion properties of zirconia materials for epithelial cell attachment and compare this with titanium and alumina. Materials and Methods Human oral epithelial cells were cultured on smooth-surfaced specimens of commercially pure titanium ( cpTi), ceria-stabilized zirconia/alumina nano-composite ( P- NANOZR), yttria-stabilized zirconia ( Cercon), and alumina oxide (in Coris AL). The cell morphology, the cell viability and mRNA of integrin β4, laminin γ2, catenin δ2, and E-cadherin were evaluated by SEM, Cell- Counting Kit-8, and real-time PCR, respectively. Results Morphology of cells attached to specimens was similar among all groups. The viable cell numbers on Cercon and in Coris AL after 24 hours culture were significantly higher than for cpTi. Integrin β4, laminin γ2, and catenin δ2 mRNA expression was not different among all groups. However, at 3 and 24 hours after incubation, E-cadherin mRNA expression in the P- NANOZR group was significantly higher than for cpTi. Conclusion Zirconia may support binding of epithelial cells through hemidesmosomes comparable with titanium. Furthermore, P- NANOZR may impart resistance to exogenous stimuli through strong intercellular contacts with peri-implant mucosal cells when used as an abutment and implant superstructure. [ABSTRACT FROM AUTHOR]

Background The adhesive connection between titanium base and zirconia coping of two-part abutments may be responsible for the failure rate. A high mechanical stability between both components is essential for the long-term success. Purpose The aim of the present in-vitro study was to evaluate the influence of different surface modification techniques and resin-based luting agents on the retention forces between titanium and zirconia components in two-part implant abutments. Materials and Methods A total of 120 abutments with a titanium base bonded to a zirconia coping were investigated. Two different resin-based luting agents ( Panavia F 2.0 and RelyX Unicem) and six different surface modifications were used to fix these components, resulting in 12 test groups ( n = 10). The surface of the test specimens was mechanically pretreated with aluminium oxide blasting in combination with application of two surface activating primers ( Alloy Primer, Clearfil Ceramic Primer) or a tribological conditioning ( Rocatec), respectively. All specimens underwent 10,000 thermal cycles between 5° C and 55° C in a moist environment. A pull-off test was then conducted to determine retention forces between the titanium and zirconia components, and statistical analysis was performed (two-way anova). Finally, fracture surfaces were analyzed by light and scanning electron microscopy. Results No significant differences were found between Panavia F 2.0 and RelyX Unicem. However, the retention forces were significantly influenced by the surface modification technique used ( p < 0.001). For both luting agents, the highest retention forces were found when adhesion surfaces of both the titanium bases and the zirconia copings were pretreated with aluminium oxide blasting, and with the application of Clearfil Ceramic Primer. Conclusion Surface modification techniques crucially influence the retention forces between titanium and zirconia components in two-part implant abutments. All adhesion surfaces should be pretreated by sandblasting. Moreover, a phosphate-based primer serves to enhance long-term retention of the components. [ABSTRACT FROM AUTHOR]

Aim To test in vitro the mechanical resistance, rotational misfit and failure mode of three original implant-abutment connections and to compare them to two connections between non-original abutments connected to one of the original implants. Material and Methods Three different implants with small diameters (3.3 mm for Straumann Roxolid, 3.5 mm for Nobel Biocare Replace and Astra Tech Osseospeed TX) were connected with individualized titanium abutments. Twelve implants from each system were connected to their original abutments ( Straumann CARES, Nobel Biocare Procera, Astra Tech Atlantis). Twenty-four Roxolid implants were connected with non-original abutments using CAD/ CAM procedures from the other two manufacturers (12 Nobel Biocare Procera and 12 Astra Tech Atlantis). For the critical bending test, a Zwick/ Roell 1475 machine and the Xpert Zwick/ Roell software were used. Results The rotational misfit varied when comparing the different interfaces. The use of non-original grade V titanium abutments on Roxolid implants increased the force needed for deformation. The fracture mode was different with one of the original connections. Conclusions Non-original abutments differ in design of the connecting surfaces and material and demonstrate higher rotational misfit. These differences may result in unexpected failure modes. [ABSTRACT FROM AUTHOR]

This article presents a bimodal procedure for a patient with an implant-supported fixed partial denture (FP2 class of Misch) where endosteal implants (EOIs) and a subperiosteal implant (SPI) were indicated in different sections of the same arch. In edentulous patients, heterogeneous bone volume and density may be encountered in different regions of the same arch. When the available bone is favorable, the use of EOIs is simpler and less time consuming. An SPI is indicated when the available bone is severely resorbed, as in the type I division C, type II divisions C and D, and type III divisions C and D. The main advantage of the described combined technique is that it offers an alternative to invasive surgeries such as iliac crest bone grafts or various surgical augmentation procedures. The second advantage is the very brief healing period after insertion of the SPI before prosthetic loading. Planning, design, laboratory construction, surgical application, and prosthetic rehabilitation for bimodal implant treatment are described. Prefabricated titanium tissue abutments are used in the fabrication of the posts of the anterior titanium SPI. Titanium tissue abutments are placed in the waxup stage of the SPI before the casting of the titanium SPI. Posterior fixtures are EOIs. An anterior SPI with 4 posts and 4 posterior EOIs provides a combination of support for the screw-retained fixed maxillary denture of Misch's FP2. [ABSTRACT FROM AUTHOR]