One-Piece Zirconia Ceramic versus Titanium Implants in the Jaw and Femur of a Sheep Model: A Pilot Study

Shrinkage Volume, Compressive Strength, and Surface Roughness Y-TTRIA Stabilized Tetragonal Zirconia Polycrystal (Y-TZP) Using Binders Variation PVA:PEG as an Alternative Dental Implants Materials

OBJECTIVE

 Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is one of the materials that can be used as an alternative material for dental implants because of its good mechanical, biocompatible, and aesthetic properties. The binder used for ceramic processing to help bond is polyvinyl alcohol (PVA), which can increase the density of the ceramic material, and polyethylene glycol (PEG), which is used as a plasticizer for PVA, so it is pretty soft when pressed.

MATERIALS AND METHODS

 The sample was divided into five groups for volume shrinkage and compressive strength examination consisting of K1 (PVA 100%), K2 (PEG 100%), P1 (PVA:PEG 95:5), P2 (PVA:PEG 90:10), and P3 (PVA:PEG 85:15) and four groups on the surface roughness test, namely, K (PVA:PEG 1%), P1 (PVA:PEG 2%), P2 (PVA:PEG 3%), and P3 (PVA:PEG 4%). PVA:PEG binder with various concentrations was mixed with Y-TZP. The mixture was pressed using a uniaxial pressing method and continued by sintering at 1200°C for 4 hours.

STATISTICAL ANALYSIS

 Least significant difference (LSD) test result showed that there was a significant difference in the compressive strength value and shrinkage volume between groups K1 and K2 and P3, and groups K2 with P1, P2, and P3. Post hoc LSD surface roughness test showed a significant difference between groups K with P2 and P3 and P1 and P3 (p < 0.05). There were no significant differences (p > 0.05) between K with P1 and P2 with P3.

RESULTS

 The Y-TZP group with the PVA binder mixture had the highest compressive strength, while the highest volume shrinkage was found in the PEG group. The next highest compressive strength and volume shrinkage values were found in the PVA:PEG group with a ratio of 95:5, 102.44 MPa, and 12.5%. The best PVA:PEG ratio of 95:5 is used to make surface roughness measurement samples. The best results showed that mixing Y-TZP with 4% PVA:PEG binder had the highest surface roughness compared to other PVA:PEG binders, namely 1.3450 μm.

CONCLUSION

 From this study, it can be concluded that the best PVA:PEG percentage ratio to produce volume shrinkage and compressive strength is 95:5. The higher the concentration of PVA:PEG (95:5) binder mixed with Y-TZP, the higher the porosity will be.

Preventing Peri-implantitis: The Quest for a Next Generation of Titanium Dental Implants

Titanium and its alloys are frequently the biomaterial of choice for dental implant applications. Although titanium dental implants have been utilized for decades, there are yet unresolved issues pertaining to implant failure. Dental implant failure can arise either through wear and fatigue of the implant itself or peri-implant disease and subsequent host inflammation. In the present report, we provide a comprehensive review of titanium and its alloys in the context of dental implant material, and how surface properties influence the rate of bacterial colonization and peri-implant disease. Details are provided on the various periodontal pathogens implicated in peri-implantitis, their adhesive behavior, and how this relationship is governed by the implant surface properties. Issues of osteointegration and immunomodulation are also discussed in relation to titanium dental implants. Some impediments in the commercial translation for a novel titanium-based dental implant from "bench to bedside" are discussed. Numerous in vitro studies on novel materials, processing techniques, and methodologies performed on dental implants have been highlighted. The present report review that comprehensively compares the in vitro, in vivo, and clinical studies of titanium and its alloys for dental implants.

Zirconia versus Titanium Implants: 8-Year Follow-Up in a Patient Cohort Contrasted with Histological Evidence from a Preclinical Animal Model

Zirconia ceramic (ZC) implants are becoming more common, but comparisons between preclinical histology and long-term clinical trials are rare. This investigation comprised (1) 8-year clinical follow-up of one-piece ZC or titanium (Ti) implants supporting full overdentures and (2) histomorphometric analysis of the same implants in an animal model, comparing implants with various surface treatments. Methods: (1) Clinical trial: 24 completely edentulous participants (2 groups of N = 12) received 7 implants (one-piece ball-abutment ZC or Ti; maxilla N = 4, mandible N = 3) restored with implant overdentures. Outcomes after 8-years included survival, peri-implant bone levels, soft-tissue responses, and prosthodontic issues. (2) Preclinical trial: 10 New Zealand sheep received 4 implants bilaterally in the femoral condyle: Southern Implants ZC or Ti one-piece implants, identical to the clinical trial, and controls: Southern ITC^® two-piece implants with the same surface or Nobel (NBC) anodised (TiUnite™) surface. %Bone-implant contact (%BIC) was measured after 12 weeks of unloaded healing. Results: 8 of 24 participants (33%) of an average age of 75 ± 8 years were recalled; 21% of original participants had died, and 46% could not be contacted. 80.4% of implants survived; excluding palatal sites, 87.5% of Ti and 79% of ZC implants survived. All failed implants were in the maxilla. Three ZC implants had fractured. Bone loss was similar for Ti vs. ZC; pocket depths (p = 0.04) and attachment levels (p = 0.02) were greater for Ti than ZC implants. (1.7 ± 1.6 mm vs. 1.6 ± 1.3 mm). All implants in sheep femurs survived. %BIC was not statistically different for one-piece blasted surface Ti (80 ± 19%) versus ZC (76 ± 20%) or ITC^® (75 ± 16 mm); NBC had significantly higher %BIC than ITC (84 ± 17%, p = 0.4). Conclusion: Short-term preclinical results for ZC and Ti one-piece implants showed excellent bone-implant contact in unloaded femoral sites. This differed from the long-term clinical results in older-aged, edentulous participants. While ZC and Ti implants showed equivalent performance, the risks of peri-implantitis and implant loss in older, completely edentulous patients remain a significant factor.

Zirconia vs. Titanium Dental Implants: Primary Stability In-Vitro Analysis

The present experimental trial uses two types of dental implants, one made of titanium (Ti₆A_l4V) and the other one of zirconia (ZrO₂), but both of identical design, to compare their stability and micro-movements values under load. One of each type of implant (n = 42) was placed into 21 cow ribs, recording the insertion torque and the resonance frequency using a specific transducer. Subsequently, a prosthetic crown made of PMMA was screwed onto each of the implants in the sample. They were then subjected to a static compression load on the vestibular cusp of the crown. The resulting micromovements were measured. The zirconia implants obtained a higher mean of both IT and RFA when compared with those of titanium, with statistically significant differences in both cases (p = 0.0483 and p = 0.0296). However, the micromovement values when load was applied were very similar for both types, with the differences between them (p = 0.3867) not found to be statistically significant. The results show that zirconia implants have higher implant stability values than titanium implants. However, the fact that there are no differences in micromobility values implies that caution should be exercised when applying clinical protocols for zirconia based on RFA, which only has evidence for titanium.

Zirconia Materials for Dental Implants: A Literature Review

Titanium is currently the most commonly used material for manufacturing dental implants. However, its potential toxic effects and the gray color have resulted in increasing requests for metal-free treatment options. Zirconia is a type of ceramic materials that has been extensively used in medicine field, such as implant abutments and various joint replacement appliances. Amounts of clinical evaluations have indicated good biocompatibility for zirconia products. Besides, its toothlike color, low affinity for plaque and outstanding mechanical and chemical properties have made it an ideal candidate for dental implants. The aim of this study is to review the laboratory and clinical papers about several kinds of zirconia materials and zirconia surface modification techniques. Although there are plenty of literatures on these topics, most of the researches focused on the mechanical properties of the materials or based on cell and animal experiments. Randomized clinical trials on zirconia materials are still urgently needed to validate their application as dental implants.

Local tissue effects and peri-implant bone healing induced by implant surface treatment: an in vivo study in the sheep

OBJECTIVE

The aim of this study was to assess, through biological analysis, the local effects and osseointegration of dental implants incorporating surface micro/nanofeatures compared with implants of identical design without surface treatment.

BACKGROUND

Known to impact bone cell behavior, surface chemical and topography modifications target improved osseointegration and long-term success of dental implants. Very few studies assess the performance of implants presenting both micro- and nanofeatures in vivo on the animal models used in preclinical studies for medical device certification.

METHODS

Implant surfaces were characterized in terms of topography and surface chemical composition. After 4 weeks and 13 weeks of implantation in sheep femoral condyles, forty implants were evaluated through micro-computed tomography, histopathologic, and histomorphometric analyses.

RESULTS

No local adverse effects were observed around implants. Histomorphometric analyses showed significantly higher bone-to-implant contact in the coronal region of the surface-treated implant at week 4 and week 13, respectively, was 79.3 ± 11.2% and 86.4 ± 6.7%, compared with the untreated implants (68.3 ± 8.8% and 74.8 ± 13%). Micro-computed tomography analyses revealed that healing patterns differed between coronal and apical regions, with higher coronal bone-to-implant contact at week 13. Histopathologic results showed, at week 13, bone healing around the surface-treated implant with undistinguishable defect margins, while the untreated implant still presented bone condensation and traces of the initial drill defect.

CONCLUSION

Our results suggest that the surface-treated implant not only shows no deleterious effects on local tissues but also promotes faster bone healing around the implant.

Two-piece zirconia versus titanium implants after 80 months: Clinical outcomes from a prospective randomized pilot trial

OBJECTIVES

To prospectively evaluate, as part of an ongoing randomized pilot trial, the clinical outcomes of two-piece zirconia implants in comparison with titanium implants 80 months after delivery of all-ceramic (lithium disilicate) single-tooth restorations.

MATERIAL AND METHODS

The original sample included 31 (16 zirconia and 15 titanium) implants in 22 healthy patients. In addition to evaluating implant survival and success, a number of clinical or radiographic parameters were statistically analyzed: plaque index (PI), bleeding on probing (BOP), pink esthetic score (PES), and marginal bone loss (MBL). Both implant groups were compared using a Mann-Whitney U test.

RESULTS

Three implants (2 zirconia and 1 titanium) had been lost, so that 28 implants (14 zirconia and 14 titanium) in 21 patients could be evaluated after a mean of 80.9 (SD: 5.5) months. All surviving implants had remained stable, in the absence of any fixture or abutment fractures and without any chipping, fracture, or debonding of crowns. The zirconia implants were associated with PI values of 11.07% (SD: 8.11) and the titanium implants with 15.20% (SD: 15.58), the respective figures for the other parameters being 16.43% (SD: 6.16) or 12.60% (SD: 7.66) for BOP; 11.11 (SD: 1.27) or 11.56 (SD: 1.01) for PES; and 1.38 mm (SD: 0.81) or 1.17 mm (SD: 0.73) for MBL.

CONCLUSIONS

No significant differences were found between the clinical outcomes of two-piece zirconia and titanium implants based on the aforementioned parameters after 80 months of clinical service. Our results should be interpreted with the limited sample size in mind.

Modification of the Ceramic Implant Surfaces from Zirconia by the Magnetron Sputtering of Different Calcium Phosphate Targets: A Comparative Study

In this study, thin calcium phosphate (Ca-P) coatings were deposited on zirconia substrates by radiofrequency (RF) magnetron sputtering using different calcium phosphate targets (calcium phosphate tribasic (CPT), hydroxyapatite (HA), calcium phosphate monobasic, calcium phosphate dibasic dehydrate (DCPD) and calcium pyrophosphate (CPP) powders). The sputtering of calcium phosphate monobasic and DCPD powders was carried out without an inert gas in the self-sustaining plasma mode. The physico-chemical, mechanical and biological properties of the coatings were investigated. Cell adhesion on the coatings was examined using mesenchymal stem cells (MSCs). The CPT coating exhibited the best cell adherence among all the samples, including the uncoated zirconia substrate. The cells were spread uniformly over the surfaces of all samples.

Influence of crown and hybrid abutment ceramic materials on the stress distribution of implant-supported prosthesis

Abstract Introduction A new dental implant-abutment design is available with the possibility of improving aesthetic with no compromise of mechanical strength, using perforated CAD/CAM ceramic blocks. Objective This study evaluated the influence of crown and hybrid abutment ceramic materials combination on the stress distribution of external hexagon implant supported prosthesis. Method Zirconia, lithium disilicate and hybrid ceramic were evaluated, totaling 9 combinations of crown and mesostructure materials. For finite element analysis, a monolithic crown cemented over a hybrid abutment (mesostructure + titanium base) was modeled and screwed onto an external hexagon implant. Models were then exported in STEP format to analysis software, and the materials were considered isotropic, linear, elastic and homogeneous. An oblique load (30°, 300N) was applied to the central fossa bottom and the system’s fixation occurred on the bone’s base. Result For crown structure, flexible materials concentrate less stress than rigid ones. In analyzing the hybrid abutment, it presented higher stress values when it was made with zirconia combined with a hybrid ceramic crown. The stress distribution was similar regarding all combinations for the fixation screw and implant. Conclusion For external hexagon implant, the higher elastic modulus of the ceramic crowns associated with lower elastic modulus of the hybrid abutment shows a better stress distribution on the set, suggesting a promising mechanical behavior.

Thirty Years of Translational Research in Zirconia Dental Implants: A Systematic Review of the Literature

Thirty years of transitional research in zirconia (Zr) ceramics has led to significant improvements in the biomedical field, especially in dental implantology. Oral implants made of yttria-tetragonal zirconia polycrystals (Y-TZP) because of their excellent mechanical properties, good biocompatibility, and esthetically acceptable color have emerged as an attractive metal-free alternative to titanium (Ti) implants. The aim of the review was to highlight the translation research in Zr dental implants that has been conducted over the past 3 decades using preclinical animal models. A computer search of electronic databases, primarily PubMed, was performed with the following key words: "zirconia ceramics AND animal trials," "ceramic implants AND animal trials," "zirconia AND animal trials," "zirconia AND in vivo animal trials," without any language restriction. However, the search was limited to animal trials discussing percentage bone-implant contact (%BIC) around zirconia implants/discs. This search resulted in 132 articles (reviews, in vivo studies, and animal studies) of potential interest. We restricted our search terms to "zirconia/ceramic," "bone-implant-contact," and "animal trials" and found 29 relevant publications, which were then selected for full-text reading. Reasons for exclusion included the article's not being an animal study, being a review article, and not discussing %BIC around Zr implants/discs. Most of the studies investigated BIC around Zr in rabbits (30%), pigs (approximately 20%), dogs, sheep, and rats. This review of the literature shows that preclinical animal models can be successfully used to investigate osseointegration around Zr ceramics. Results of the reviewed studies demonstrated excellent %BIC around Zr implants. It should be noted that most of the studies investigated %BIC/removal torque under nonloading conditions, and results would have been somewhat different in functional loading situations because of inherent limitations of Zr ceramics. Further trials are needed to evaluate the performance of Zr ceramics in clinical conditions using implants designed and manufactured via novel techniques that enhance their biomechanical properties.