Effect of Decontamination and Cleaning on the Shear Bond Strength of High Translucency Zirconia

Cleaning methods of contaminated zirconia: A systematic review and meta-analysis

OBJECTIVES

The aims of this study were to systematically review the literature and statistically analyze the effectiveness of different cleaning methods on the bond strength of resin cement to zirconia in short- and long-term aging conditions.

DATA/SOURCES

The literature was electronically searched in PubMed (MEDLINE), EMBASE, Wiley, Scopus, and Open Access Theses and Dissertations databases to select relevant articles that evaluated the bond strength between contaminated zirconia and resin cements. A manual search was performed by scanning the reference lists of included studies.

STUDY SELECTION

All articles were published online before April 2022 and in English. Meta-analyses were conducted using random effects models to calculate standardized mean differences (SMD) between uncontaminated zirconia and various cleaning methods in two aging conditions (short- and long-term). Statistical heterogeneity was assessed using I-square statistics. The risk of bias of all included studies was assessed. All statistical analyses were conducted using STATA (StataCorp, College Station, Texas).

RESULTS

Of the 1181 studies, 25 studies met the inclusion criteria for qualitative analyses. In short-term aging condition, cleaning contaminated zirconia with water, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. For long-term aging condition, cleaning contaminated zirconia with water, cleaning agents, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. Alumina air-abrasion or cleaning with sodium hypochlorite were comparable to uncontaminated zirconia for both short- and long-term aging conditions.

CONCLUSIONS

This meta-analysis appeared to indicate that the cleaning methods of contaminated zirconia restoration have an effect on zirconia bonding.

Effect of different cleansing methods on the artificially aged bond strength of resin to contaminated zirconia: A systematic review

PURPOSE

The aim of this review was to evaluate studies investigating the effect of cleansing methods on the artificially aged bond strength of resin to contaminated zirconia restorations and determine which cleansing method of contaminated zirconia for resin bonding improvement is more efficient.

METHODS

An electronic search of published studies in English language was carried out until July 2021 on Scopus, Web of Science, and Medline databases. Data from in vitro studies involving the evaluation of the artificially aged bond strength of resin to contaminated zirconia following different cleansing methods were included. In vitro studies in which samples were not subjected to at least 5000 thermocycles, were excluded.

RESULTS

Of 162 articles retrieved initially, 19 were eligible to be included in the systematic review, of which 5 articles were excluded. Therefore, the final sample was 14 in vitro studies. All of the included studies for air abrasion suggested this method as an effective cleansing method, but 6 of 8 included studies reported cleaning paste (Ivoclean) as an effective cleansing method. All of the included studies for NaOCl and a cleaning gel (AD Gel) reported their efficacy. Finally, the results of included studies showed the ineffectiveness of phosphoric acid, water, isopropanol, enzymatic detergents, hydrogen peroxide, and acetone.

CONCLUSIONS

Air abrasion has been reported as an effective cleansing method to improve the bond strength of resin to contaminated zirconia. To improve the effectiveness of cleaning paste in resin bonding, another efficient cleansing method should be followed after this method. However, the superior cleaning potential of air abrasion rather than cleaning paste has been reported. Sodium hypochlorite and cleaning gel seem to be as effective as air abrasion, but extensive water-rinsing is necessary after the application of these cleaning agents.

Effect of ethyl cellulose coating as an evaluation agent against contamination on the bond strength of zirconia restorations: An in vitro study

STATEMENT OF PROBLEM

During the trial placement of zirconia restorations, contamination of the bonding surface is inevitable. Although cleaning methods for contaminated surfaces have been described, a method of preventing saliva contamination of the bonding surface of zirconia restorations is lacking.

PURPOSE

The purpose of this in vitro study was to investigate an ethyl cellulose coating as an evaluation agent to mitigate the effects of saliva contamination on the bond strength of zirconia restorations.

MATERIAL AND METHODS

Experimental groups representing different cleaning methods of tetragonal yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP) surfaces were investigated for shear bond strength with a resin luting agent, and the failure mode was analyzed. The 9.0×7.0×5.0-mm zirconia blocks (n=72) were assigned as follows: Group N: uncontaminated control; Group CU: contaminated with saliva, followed by ultrasonic cleaning with ethanol; Group CI: contaminated with saliva, followed by application of a zirconia cleaner; Group PCW: preapplication of a zirconia primer, contaminated with saliva, followed by cleaning with water spray; Group ECU: precoating with the ethyl cellulose agent, contaminated with saliva, followed by removal of the agent in an ultrasonic bath with ethanol. Each group was divided into 3 subgroups (immediate, short-term aging, and long-term aging), and the shear bond strength was measured (n=24). To analyze the bonding surface characteristics, the contact angle was measured (n=5). The surfaces of the zirconia specimens in each experimental group were evaluated by using a field emission scanning electron microscope (n=5). Time-of-flight secondary ion mass spectroscopy was used for the chemical analysis of the conditioned surfaces (n=3). A 2-way analysis of variance (ANOVA) with main effect model for shear bond strength results and a 1-way ANOVA for contact angle data were performed as statistical analysis, followed by the Bonferroni post hoc test (α=.05).

RESULTS

The shear bond strength was significantly higher in the ECU group than in the groups with the other cleaning methods (P<.05). After the removal of ethyl cellulose with ethanol, the contact angle and surface topography were found to be similar to those of the control group, and no saliva contaminants were identified in the spectroscopy analysis.

CONCLUSIONS

Coating with ethyl cellulose may protect the bonding surface of zirconia restorations from salivary contamination better than cleaning a contaminated surface.

Cleaning Zirconia Surface Prior To Bonding: A Comparative Study of Different Methods and Solutions

PURPOSE

To evaluate resin cement bond strength after removal of salivary contamination from a zirconia surface using different cleaning solutions and air-borne particle abrasion.

MATERIALS AND METHODS

One-hundred and twenty zirconia specimens (KATANA STML, Noritake) were prepared and divided into 12 groups (n = 10). Groups were subjected to a notched-edge shear bond strength test (ISO 29022) to analyze the bonding efficiency of a resin cement (Panavia V5, Kuraray Noritake Dental Inc.) before and after contamination with saliva. Group 1 (control) was prepared and cemented without salivary contamination. Group 2 was coated with ceramic primer (Clearfil Ceramic Primer Plus, Kuraray Noritake Dental Inc.) then subjected to salivary contamination then tested. Group 3 was contaminated, cleaned by air-borne particle abrasion, ceramic primer and resin cement applied, and tested. Groups 4 to 12 were contaminated, and then different cleaning solutions (water, 4.5% hydrofluoric acid, 35% phosphoric acid, Ivoclean, KATANA cleaner, Zirclean, sodium hypochlorite 4%, and 7.5%) were used to decontaminate the zirconia surface, followed by ceramic primer, resin cement application, and tested. One-way ANOVA and Tukey post-hoc analysis was used to analyze the data.

RESULTS

One-way ANOVA showed statistical differences among cleaning procedures (p < 0.001, F = 13.48). Air-borne particle abrasion was the only group which provided a bond strength (21 ± 2.8 MPa) that was not statistically different than the control group in which no contamination occurred (25.3 ± 3.3 MPa) (p = 0.247). The use of hydrofluoric acid and zirconia cleaning solutions resulted in bond strengths values which were not statistically different from each other (17.5-19.1 MPa).

CONCLUSION

Air-borne particle, zirconia cleaning solutions and hydrofluoric acid are feasible to decontaminate the zirconia surface from saliva prior to bonding the restoration.

Bonding to zirconia: Effects of translucency and cusp inclinations using an experimental methodology

Purpose To investigate the effects of translucency and cusp inclination on the micro-shear bond strength (µSBS) of zirconia to self-adhesive resin cement (SARC).Methods Sixty U-shaped zirconia specimens with 1.0 mm thickness consisting of three planes (0°, 20°, and 30°) simulating different cusp inclinations were fabricated from zirconia blocks of high, moderate, and low translucency (n=20). SARC was bonded to the specimen and light-cured for 40 s. The µSBS was tested using a universal testing machine with a cross-head at a speed of 0.5 mm/min and fracture mode was observed using a stereomicroscope (×50). Two-way analysis of variance followed by a post hoc Tukey's honest significant difference test was used for the statistical analyses (α=0.05).Results Varied µSBS values were found in the test groups (7.1-14.9 MPa). Within the zirconia of the same translucency, the µSBS value of the plane 0° specimen was significantly higher than that of the 20° and 30° planes (all p<0.05). Within the zirconia of the same cusp inclination, the µSBS value of highly translucent zirconia was significantly higher than that of moderate and low translucent zirconia (all p<0.05). There was no significant interaction between cusp inclination and translucency (p=0.525). Among the fracture modes, 83.33% were adhesive failure, 11.11% mixed failure, and 5.56% were cohesive failure.Conclusions Translucency and cusp inclination significantly affect the µSBS of zirconia to SARC. The higher the translucency, the greater are the µSBS values; the higher the cusp inclination, the lower are the µSBS values.

Patient satisfaction and masticatory performance of zirconia bar compared to cobalt chromium bar retaining mandibular implant overdenture: A crossover study

OBJECTIVES

The aim of this crossover clinical study was the evaluation and comparison of patient satisfaction and masticatory performance for patients rehabilitated with mandibular two implant overdentures retained with two different bar attachments: zirconia bar and cobalt chromium bar.

MATERIAL AND METHODS

Twenty completely edentulous patients were divided into two equal groups: Group I (ZrO2), each patient received mandibular implant overdenture retained with CAD/CAM zirconia bar on two implants in the canine region, and Group II (Co-Cr), each patient received mandibular overdenture retained with conventional casted cobalt chromium metal bar. Patient satisfaction was measured with a survey questionnaire (PSQ-18), and masticatory performance was also evaluated with the two-colour mixing ability test after 3 months of overdenture insertion; then, each patient received a bar attachment from the other type and evaluations were repeated.

RESULTS

Significant differences were observed regarding psychological acceptance (appearance), time, hygiene, undergo procedures, recommend procedures and the overall experience. In contrast, insignificant difference was observed regarding speech, chewing capacity, restorative procedures, complications and information prior to treatment. No significant difference was reported when comparing chewing performance between the two types of bar attachment.

CONCLUSION

Within this clinical study limitations, patient satisfaction with zirconia bar was higher than Co-Cr bar in terms of appearance, time, hygiene, undergo procedures, recommend procedures and the overall experience. Zirconia can become a suitable alternative to cobalt chromium alloys as a bar attachment. Combining the advantages of implant supported overdenture, CAD/CAM zirconia bar as an attachment, a satisfactory non-metal prosthesis could be provided.

Comparison between different surface treatment methods on shear bond strength of zirconia (in vitro study)

Background

To compare the effect of Er:YAG Laser and Air particle abrasion (APA) surface treatments on shear bond strength of Y-TZP to composite resin cuboids in the presence and absence of primer application and salivary contamination.

Material and Methods

Seventy-two cuboidal shaped specimens 7x7x3 were prepared from Y-TZP using CADCAM, cleaned and sintered. Specimens were divided into 2 main groups (n=36) according to surface treatment method; Air particle abrasion (A) and laser (L). Each group was subdivided into 2 subgroups (N = 18) according to surface modification using primer; each subgroup was further divided into 2 subdivisions (N=9) according to the presence of salivary contamination; APC (Air particle abrasion, primer, contamination), AP (Air particle abrasion, primer), AC (Air particle abrasion, contamination), A (Air particle abrasion), LPC (Laser, primer, contamination), LP (Laser, primer), LC (Laser, contamination), L (Laser). Composite cuboids having dimensions of 6x6x3 were also fabricated using custom made plexi plates. Composite cuboids were cemented centrally to zirconia cuboids and light cured under 5 kg weight for 6 mins. Shear bond strength of specimens was measured utilizing universal testing machine at a crosshead speed of 0.5 mm/min. Failure loads were recorded in Newton. SBS was calculated according to equation: SBS (MPa) = load (N)/area(mm2).

Results

Viewing shear bond strength between studied groups, group APNC (484.02±85.02) showed higher mean value compared to ANPNC (122.09±55.80), also LNPNC (120.87±65.10) showed higher mean value in comparison to LPNC (170.78±53.22). APNC (484.02±85.02) and APC (592.22±189.65) showed higher mean values than LPNC (170.78±53.22) and LPC (3227.66±108.28) in sequence.

Conclusions

APA showed higher SBS values than Er:YAG surface treatment. Primer showed better results than no primer coating. Artificial saliva contamination did not affect the SBS of zirconia compared with no contamination results. Key words:Shear bond strength, zirconia, air particle abrasion, Er:YAG laser, primer, contamination.

Bonding Strength of Universal Adhesives to Indirect Substrates: A Meta-Analysis of in Vitro Studies

PURPOSE

To evaluate the in vitro bond strength of universal adhesive systems to indirect substrates.

MATERIAL AND METHODS

Two reviewers performed a literature search up to March 2018 in seven databases: PubMed, Web of Science, SciELO, Scopus, LILACS, IBECS, and BBO. The review included studies that compared the bond strength of universal adhesives and well-established material-specific primers to indirect substrates: lithium disilicate ceramic, yttrium-stabilized zirconium dioxide ceramic, leucite-reinforced ceramic, feldspathic porcelain, polymer infiltrated ceramic material, resin composite or metal alloys. Analyses were carried out using RevMan 5.3.5. A global comparison was performed with the standardized mean difference using a random-effects models at a significance level of p < 0.05.

RESULTS

A total of 45 studies were included in the qualitative analysis, and the meta-analysis was performed with 42 studies. Bond strength to glass-based ceramics and alloys was improved with the use of a specific-primer as separate step before the bonding procedures (lithium disilicate, p < 0.001; alloys, p < 0.001). The bond strength to zirconium substrates was improved with the use of universal adhesives (p < 0.001). For bond strength to composite resin as indirect substrate, universal adhesives performed in a manner similar to that of the material-specific primer (p = 0.11).

CONCLUSIONS

The clinical procedure of luting zirconia and resin composite restorations could be simplified by using single-bottle universal adhesives. However, the ability of universal adhesives to achieve an adequate and durable bond to glass-based ceramics and alloys appears to be limited.

Effect of Decontamination Treatments on Micro-Shear Bond Strength between Blood-Saliva-Contaminated Post-Etched Dentin Substrate and Composite Resin

Blood–saliva contamination negatively affects the bonding potential of adhesive agents. The study aimed to assess the effect of various cleaning protocols on micro-shear bond strength (μSBS) between blood–saliva-contaminated post-etched dentin and composite resin in total-etch and self-etch adhesives. The cleaning methods tested were water rinsing, 37.5% phosphoric acid (H3PO4) re-etching, 6% sodium hypochlorite (NaoCl), 2% chlorhexidine gluconate (CXG), isopropyl alcohol (IPA), and pumice. Nono-hybrid composite cylinders with a 3-mm diameter and 2-mm height were directly cured over the dentin substrate, stored for 24 h, and subjected to 12,000 thermocycles. The shear force was exerted with a 200-μm knife-edged chisel-shaped head from a universal testing machine. The type of failure was assessed with stereomicroscope magnified images. The obtained data were evaluated by Kruskal–Wallis and Mann–Whitney U post-hoc tests. Water-rinsed contaminated dentin surfaces showed substantially reduced μSBS in the total etch from 25.93 to 20.29 Mpa and the corresponding values for the one-step self-etch adhesive were 10.10 to 8.8. Re-etching with 37.5% H3Po4 resulted in a recovery of bonding potential in both total-etch (24.58 Mpa) and self-etch adhesive (9.23 Mpa). Alternately, NaoCl and pumice cleaning showed promising results for the total-etch (23.51 Mpa) and self-etch (7.79 Mpa).