A single-tooth, two-piece zirconia implant located in the anterior maxilla: a clinical report

Nano-topographical surface engineering for enhancing bioactivity of PEEK implants (in vitro-histomorphometric study)

OBJECTIVES

Dental implants are currently becoming a routine treatment decision in dentistry. Synthetic polyetheretherketone (PEEK) polymer is a prevalent component of dental implantology field. The current study aimed to assess the influence of Nd:YAG laser nano-topographical surface engineering combined with ultraviolet light or platelet rich fibrin on the bioactivity and osseointegration of PEEK implants in laboratory and animal testing model.

MATERIALS AND METHODS

Computer Aided Design-Computer Aided Manufacturing (CAD CAM) discs of PEEK were used to fabricate PEEK discs (8 mm × 3 mm) N = 36 and implant cylinders (3 mm × 6 mm) N = 72. Specimens were exposed to Nd:YAG laser at wavelength 1064 nm, and surface roughness topography/Ra parameter was recorded in nanometer using atomic force microscopy. Laser modified specimens were divided into three groups: Nd:YAG laser engineered surfaces (control), Nd:YAG laser/UV engineered surfaces and Nd:YAG laser/PRF engineered surfaces (N = 12 discs-N = 24 implants). In vitro bioactivity test was performed, and precipitated apatite minerals were assessed with X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). In vivo histomorphometric analysis was performed in rabbits with BIC% calculation.

RESULTS

Ra mean value of PEEK laser engineered surfaces was 125.179 nm. For the studied groups, XRD patterns revealed distinctive peaks of different apatite minerals that were demonstrated by SEM as dispersed surface aggregations. There was a significant increase in the BIC% from control group 56.43 (0.97) to laser/UV surfaces 77.30 (0.78) to laser/PRF 84.80 (1.29) (< 0.0001).

CONCLUSIONS

Successful engineered nano-topographical biomimetic PEEK implant could be achieved by Nd:YAG laser technique associated with improving bioactivity. The combination with UV or PRF could be simple and economic methods to gain more significant improvement of PEEK implant surface bioactivity with superior osteointegration.

Effect of Plasma Treatment and Its Post Process Duration on Shear Bonding Strength and Antibacterial Effect of Dental Zirconia

We have investigated the effect of non-thermal atmospheric pressure plasma (NTAPP) treatment and the post process time on the bonding strength and surface sterilization of dental zirconia. Presintered zirconia specimens were manufactured as discs, and then subjected to a 30-min argon treatment (Ar, 99.999%; 10 L/min) using an NTAPP device. Five post-treatment durations were evaluated: control (no treatment), P0 (immediate), P1 (24 h), P2 (48 h), and P3 (72 h). The surface characteristics, shear bonding strength (SBS) with two resin cements, and Streptococcus mutans biofilm formation of these plasma-treated dental zirconia were tested. Plasma did not change the roughness, and caused surface element changes and surface energy increase. Due to this increase in surface energy, SBS increased significantly (p < 0.05) within 48 h when RelyX^TM U200 was used. However, the increase of surface oxygen significantly decreased (p < 0.05) the SBS of Panavia F 2.0 when using plasma immediately (P0). S. mutans adhesion decreased significantly (p < 0.05) for the P0, P1, and P2 groups compared to the control. The P0 group exhibited lower biofilm thickness than the other experimental groups due to the increased hydrophilicity (p < 0.05). Our study suggests that there is a suitable time window for the post NTAPP treatment regarding bonding strength and antimicrobial growth persist.

Clinical reliability of zirconium abutment in implant restorations in the English and Korean literature

Background

This study aimed to evaluate the mechanical, biological, and esthetic stability of a zirconium abutment according to evidence-based dentistry.

Main text

An electronic search was performed. Domestic studies were found using the keywords “zirconia abutments” and “zirconium abutment” in KMbase, KoreaMed, and the National Assembly Library, and international studies were found using the same keywords in PubMed. All identified studies were divided by evidence level from the viewpoint of the research type utilizing the evidence-based review manual. A total of 102 domestic studies (with Korean language) were found, and 9 of these studies were selected. In these nine studies, 3 had evidence level 3 and 6 had evidence level 4. A total of 97 international studies (with English language) were found, and 19 were selected. Among these 19 studies, 5 had evidence level 2 and 7 had evidence level 3, whereas the remainder had evidence level 4. According to the studies, zirconium abutments are mechanically, biologically, and esthetically stable, but the evidence level of these studies is low, and the follow-up duration is no longer than 5 years.

Conclusions

All examined studies verified the mechanical stability of zirconium abutments for a period no longer than 5 years. Therefore, a long-term clinical observation is needed. Zirconium abutments are thought to be biologically stable, but they are not superior to titanium abutments. As the esthetic stability of such abutments had a low evidence level in the studies that examined here, a much higher evidence level is needed.

Production of bone mineral material and BMP-2 in osteoblasts cultured on double acid-etched titanium

Background

The study of osteoblasts and their osteogenic functions is essential in order to understand them and their applications in implantology. In this sense, this study try to study BMP-2 production and bone matrix deposition, in addition to other biological variables, in osteoblasts cultured on a rough double acid-etched titanium surface (Osseotite®, Biomet 3i, Palm Beach Garden, Florida, USA) in comparison to a smooth titanium surface (machined) and a control Petri dish.

Material and Methods

An in vitro prospective study. NHOst human osteoblasts from the femur were cultured on three different surfaces: Control group: 25-mm methacrylate dish (n = 6); Machined group: titanium discs with machined surface (n = 6) and Experimental group: titanium discs with a double acid-etched nitric and hydrofluoric Osseotite® acid surface (n = 6). A quantification of the mitochondrial membrane potential, and studies of apoptosis, mobility and adhesion, bone productivity (BMP-2) and cellular bone synthesis were carried out after culturing the three groups for forty-eight hours.

Results

A statistically significant difference was observed in the production of BMP-2 between the experimental group and the other two groups (22.33% ± 11.06 vs. 13.10% ± 5.51 in the machined group and 3.88% ± 3.43 in the control group). Differences in cellular bone synthesis were also observed between the groups (28.34% ± 14.4% in the experimental group vs. 20.03% ± 6.79 in the machined group and 19.34% ± 15.93% in the control group).

Conclusions

In comparison with machined surfaces, Osseotite® surfaces favor BMP-2 production and bone synthesis as a result of the osteoblasts in contact with it.

Key words:BMP-2, Cytoskeleton, cell culture, bone matrix, apoptosis, cell viability.

A systematic review of the clinical survival of zirconia implants

OBJECTIVES

The aim of this review was to evaluate the clinical success and survival rates of zirconia ceramic implants after at least 1 year of function and to assess if there is sufficient evidence to justify using them as alternatives to titanium implants.

MATERIALS AND METHODS

An electronic search in MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Clinical Trials (CENTRAL) databases was performed in April 2015 by two independent examiners to retrieve clinical studies focusing on the survival rate of zirconia implants after at least 1 year of function. Implant survival was estimated using the overall proportion reported in the studies with a Clopper-Pearson 95 % confidence interval (random effect model with a Der-Simonian Laird estimate).

RESULTS

Fourteen articles were selected out of the 1519 titles initially screened. The overall survival rate of zirconia one- and two-piece implants was calculated at 92 % (95 % CI 87-95) after 1 year of function. The survival of implants at 1 year for the selected studies revealed considerable heterogeneity.

CONCLUSIONS

In spite of the unavailability of sufficient long-term evidence to justify using zirconia oral implants, zirconia ceramics could potentially be the alternative to titanium for a non-metallic implant solution. However, further clinical studies are required to establish long-term results, and to determine the risk of technical and biological complications. Additional randomized controlled clinical trials examining two-piece zirconia implant systems are also required to assess their survival and success rates in comparison with titanium as well as one-piece zirconia implants.

CLINICAL RELEVANCE

Zirconia implants provide a potential alternative to titanium ones. However, clinicians must be aware of the lack of knowledge regarding long-term outcomes and specific reasons for failure.

Evaluation of stress distributions occurring on zirconia and titanium implant-supported prostheses: A three-dimensional finite element analysis

STATEMENT OF PROBLEM

Titanium implants have been successfully used to support fixed dental prostheses. Zirconia implants have been suggested as support for crowns, but information on their use to support partial fixed dental prostheses is limited.

PURPOSE

The purpose of this finite element study was to evaluate the maximum principal, minimum principal, and von Mises stresses and their distributions on zirconia and titanium implant-supported, partial fixed dental prostheses located in the anterior maxillary region.

MATERIAL AND METHODS

Zirconia and titanium implants (4 mm in diameter and 11. 5 mm in length) and prostheses made from 2 different materials (lithium disilicate and zirconia) were simulated, and 4 models were generated: Titan-IPS, Titan-Lava, Zircon-IPS, and Zircon-Lava. The maxillary bone was modeled as type 3 bone. The load was applied obliquely (534 N) and horizontally (76.5 N), and the stress values and distributions were examined.

RESULTS

Under horizontal loading, stresses generated on the cortical bone in the Zircon models were lower than those in the Titan models. Under oblique loading, stress values were similar in the same implant material and stress type. For all types of stress among the models, the stress values that occurred on the trabecular bone were found to be similar under both horizontal and oblique loading. The maximum stress values on the bones, implants, cores, and veneers did not exceed the strength of the structures.

CONCLUSIONS

Different stress values resulted from the different implant types. The prosthetic materials did not change the stress distributions in bone.

In vitro performance of two-piece zirconia implant systems for anterior application

OBJECTIVES

To investigate the influence of the implant-abutment connection on the long-term in vitro performance and fracture resistance of two-piece zirconia implant systems for anterior application.

METHODS

Six groups of two-piece zirconia implant systems (n=10/group) with screw-retained (5×) or bonded (1×) connections were restored with full-contour zirconia crowns. A two-piece screw-retained titanium system served as reference. For simulating anterior loading the specimens (n=8/group) were mounted at an angle of 135° in the chewing simulator, and subjected to thermal cycling (TC: 2×9000×5°/55°C) and mechanical loading (ML: 3.6×10(6)×100N). Failed restorations were examined (scanning electron microscopy). Fracture resistance and maximum bending stress of surviving restorations were determined. 2 specimens per group were loaded to fracture after 24h water storage without TCML. Data were statistically analyzed (ANOVA; Bonferroni; Kaplan-Meier-Log-Rank; α=0.05).

RESULTS

The bonded zirconia system and the titanium reference survived TCML without any failures. Screw-retained zirconia systems showed fractures of abutments and/or implants, partly combined with screw fracture/loosening. Failure frequency (F) varied between the groups (F=8×: 3 groups, F=3×: 1 group, F=1×: 1 group). The Log-Rank-test showed significant (p=0.000) differences. Fracture forces and maximum bending stresses (mean±standard deviation) differed significantly (

ANOVA

p=0.000) between 233.4±31.4N/317.1±42.6N/mm(2) and 404.3±15.1N/549.2±20.5N/mm(2). Fracture forces after TCML were similar to 24h fracture forces.

SIGNIFICANCE

Screw-retained two-piece zirconia implant systems showed higher failure rates and lower fracture resistance than a screw-retained titanium system, and may be appropriate for clinical anterior requirements with limitations. Failures involved the abutment/implant region around the screw, indicating that the connecting design is crucial for clinical success.

In vitro performance of zirconia and titanium implant/abutment systems for anterior application

OBJECTIVES

To investigate the type of failure and fracture resistance behaviour of different zirconia and titanium implant/abutment systems for anterior application.

METHODS

Eight groups of implant-abutment combinations (n=8/system) were restored with identical full-contour zirconia crowns. The systems represented one-piece and multi-piece zirconia (Z) or titanium (T) implants/abutments with different types of connection (screwed=S, bonded=B). The following combinations (implant-abutment-connection) were investigated: ZZS, ZZB, ZZZB (three-piece), ZTS, TTS, TTS reference, and Z (one-piece, 2×). To simulate clinical anterior loading situations the specimens were mounted into the chewing simulator at an angle of 135° and subjected to thermal cycling (2×3000×5°/55°C) and mechanical loading (1.2×10(6)×50N; 1.6Hz). Fracture resistance and maximum bending stress were determined for all specimens that survived ageing. Data were statistically analyzed with the Kolmogorov-Smirnov-test and one-way ANOVA (α=0.05). Survival performance was calculated with the Kaplan-Meier Log-Rank test.

RESULTS

Independent of the material combinations screwed systems showed partly failures of the screws during simulation (ZZS: 3×, ZTS: 8×, TTS: 3×). Screw failures were combined with implant/abutment fractures of zirconia systems. Zirconia one-piece implants and the reference system did not show any failures, and only one specimen of the systems with a bonded connection (ZZZB) fractured. Mean (±standard deviation) fracture forces and maximum bending stresses differed significantly (p=0.000) between 187.4±42.0N/250.0±56.0N/mm(2) (ZZZB) and 524.3±43.1N/753.0±61.0N/mm(2) (Z).

CONCLUSIONS

Both material (zirconia or titanium) and the type of connection influenced failure resistance during fatigue testing, fracture force, and maximum bending stress.

CLINICAL SIGNIFICANCE

Different material combinations for implants and abutments as well as different types of connection achieved acceptable or even good failure and fracture resistance that may be satisfactory for anterior clinical application.