Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

Fracture resistance and failure mode of endodontically treated premolars reconstructed by different preparation approaches: Cervical margin relocation and crown lengthening with complete and partial ferrule with three different post and core systems

PURPOSE

To assess the fracture resistance and failure mode of endodontically treated premolars reconstructed by different preparation approaches: cervical margin relocation (CMR) and crown lengthening (CL) with complete ferrule (CLF) and partial ferrule (CLPF) with three different post and core systems.

MATERIALS AND METHODS

In this in vitro study, 100 maxillary premolars were assigned to the following 10 groups according to their preparation approach and type of post and core system (n = 10): (I) control (intact teeth), (II) prefabricated fiber post (PFP) and composite core with CMR (PFP-CMR), (III) polyethylene fiber-reinforced composite (PEFRC) with CMR (PEFRC-CMR), (IV) casting post (CP) and core with CMR (CP-CMR), (V) PFP-CLPF, (VI) PEFRC-CLPF, (VII) CP-CLPF, (VIII) PFP-CLF, (IX) PEFRC-CLF, and (X) CP-CLF. After thermomechanical loading, the fracture resistance and failure mode were assessed. Data were analyzed statistically (α = 0.05).

RESULTS

In all post and core systems, the CLPF approach had lower fracture resistance than CMR (p < 0.05); CLF showed higher fracture resistance than CLPF only in the PFP system (p = 0.038). In PEFRC and CP systems, the difference between CLF and CLPF was not significant (p > 0.05). No significant difference was found in fracture resistance of different post and core systems with the same preparation approach (p > 0.05). CLPF showed the highest frequency of favorable, and CLF showed the highest frequency of unfavorable fractures.

CONCLUSION

CLPF yielded lower fracture resistance than CMR. The difference in fracture resistance was not significant between CLF and CMR but the frequency of unfavorable fractures was higher in CLF than in other groups.

Shear bond strength of orthodontic brackets to single-shade composite surfaces: An in-vitro comparative study of different surface preparations

PURPOSE

The primary objective of this study was to determine which single-shade composite surface yielded clinically acceptable shear bond strength (SBS) to metal orthodontics brackets. The secondary objectives were to identify the best composite surface treatment to enhance SBS and determine which surface treatment produced the least surface damage at debond.

METHODS

Forty dental composite samples were selected from four different manufacturers (n=160) and grouped by manufacturer, one standard multi-shade dental system (FilTek™ Supreme Ultra) and three single-shade dental composites systems (OmniChroma®, SimpliShade™ and Venus® Diamond One). Each group of forty samples was randomly divided into four sub-groups (n=10). Each sub-group was identified by the surface treatment used, hydrofluoric acid (HFA), micro-etching (MIC), or phosphoric acid (PA). Shear bond strength testing and adhesive remnant index (ARI) were performed. Statistical analyses included Kruskal-Wallis, Wilcoxon rank-sum, and two-factorial ANOVA.

RESULTS

OmniChroma® had statistically significant lower shear bond strength than the other composite materials tested. The control groups had statistically significant lower shear bond strength than Group 1/HFA (P<0.001) and Group 2/MIC (P<0.001). Group 1/HFA had the lowest distribution ARI score overall, while MIC had the highest ARI score distributions.

CONCLUSIONS

The results of this in-vitro study found that all tested composite materials achieved clinically acceptable shear bond strengths. The utilization of micro-etching produced higher SBS. Significant Adhesive Remnant Index scores (< 0.001) were only found for OmniChroma® without any surface preparation.

Shear bond strength of orthodontic brackets bonded to high-translucent dental zirconia with different surface treatments: An in vitro study

PURPOSE

The objective of this study was to compare the shear bond strengths of orthodontic brackets bonded to translucent dental zirconia samples which are anatomically accurate and treated with various surface treatments.

METHODS

This in vitro study included 156 samples from 3 brands of high-translucent zirconia split into a control group and 4 surface treatment groups: 9.6% hydrofluoric acid etching, 50-micron aluminium oxide particle air abrasion, and 30-micron tribochemical silica coating (TBS) particle air abrasion with and without silane application. After surface treatment, all groups were primed with a 10-MDP primer and bonded to metal orthodontic brackets. Shear bond strength (SBS) was tested and results were compared between all groups. Data analysis consisted of a balanced two-factor factorial ANOVA, a Shapiro-Wilks test, and a non-parametric permutation test. The significance level was set at 0.05.

RESULTS

Among all surface treatments, aluminium oxide particle abrasion produced significantly higher SBS (P≤0.002). Lava™ Plus zirconia samples had significantly higher SBS than Cercon® samples (P<0.0001). TBS surface treatment produced significantly higher SBS on Lava™ Plus samples than it did on the other zirconia brands (P=0.032).

CONCLUSIONS

This study indicated that mechanical abrasion using aluminium oxide in combination with a 10-MDP primer creates a higher SBS to high-translucent zirconia than the bond created by tribochemical silica coating. Also, there was no significant difference in ARI regardless of zirconia brand or surface preparation.

Influence of different surface treatment on bonding of metal and ceramic Orthodontic Brackets to CAD-CAM all ceramic materials

BACKGROUND

Developing efficient bonding techniques for orthodontic brackets and all-ceramic materials continues to pose a clinical difficulty. This study aimed to evaluate the shear bond strengths (SBS) of metal and ceramic brackets to various all-ceramic CAD-CAM materials, such as lithium disilicate CAD (LDS-CAD), polymer-infiltrated ceramic (PIC), zirconia-reinforced lithium silicate glass ceramic (ZLS), and 5YTZP zirconia after different surface treatments and thermal cycling.

MATERIALS AND METHODS

The samples were divided into two groups to be bonded with ceramic and metal lower incisor brackets. Each group was subdivided into a control group devoid of any surface treatment, 10% HF acid (HFA) etching, ceramic etch & prime (MEP), Al2O3 air abrasion, and medium grit diamond bur roughening. After surface treatment, brackets were bonded with composite resin cement, thermal cycled, and tested for shear bond strength. The failed surfaces were evaluated with a digital microscope to analyse the type of failure. The data were statistically analysed using a one-way ANOVA and Tukey HSD tests at p < 0.05.

RESULTS

The highest mean bond strengths were found with HFA etching in LDS-CAD (13.17 ± 0.26 MPa) and ZLS (12.85 0.52 MPa). Diamond bur recorded the lowest mean bond strength roughening across all the ceramic groups. There were significant differences in mean shear bond values per surface treatment (p < 0.001) and ceramic materials.

CONCLUSION

Among the surface treatment protocols evaluated, HFA etching and MEP surface treatment resulted in enhanced bond strength of both ceramic and metal brackets to CAD-CAM all ceramic materials.

Shear Bond Strength between Orthodontic Brackets and Monolithic 4Y-TZP: An In Vitro Study

The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) between metal orthodontic brackets and monolithic zirconia surfaces bonded with resin composite. Fifty monolithic zirconia (4Y-TZP) disks were sintered and glazed. Specimens were divided into five groups (n = 10) for different surface treatments: control, nano second fiber laser, sandblasting, grinding and tribochemical coating (CoJet Sand 30-μm). Metal orthodontic brackets were bonded to monolithic zirconia surface by two-component orthodontic adhesive. After 500 cycles of thermocycling, shear bond strength values were measured by a universal testing machine at a cross head speed of 0.5 mm/min. The data was recorded as MPa and statistically analyzed with One-way ANOVA, Levene's LSD tests with Bonferroni corrections. The significance level was α = 0.05. The surface topography of one specimen of each group was evaluated by scanning electron microscopy (SEM). Statistically significant difference was observed among study groups (p = 0.018). The lowest shear bond strength was observed in the control group (3.92 ± 1.9). Tribochemical coating showed the highest bond strength (7.44 ± 2.9), which was statistically different from the control and nano second laser (4.3 ± 1.4) groups but not statistically different from grinding (6.15 ± 3.1) or sandblasting (6.47 ± 3.3). SEM images showed comprehensive results of each surface treatment on monolithic zirconia. All failure modes were recorded as adhesive between the composite resin and monolithic zirconia. Based on the findings of this study, it can be concluded that grinding, sandblasting and tribochemical coating techniques showed clinically acceptable bond strength within the range of 6-8 MPa. These surface treatments can be considered suitable for achieving a durable bond between metal orthodontic brackets and monolithic 4Y-TZP ceramic surfaces.

Shear bond strength of orthodontic molar tubes to composite restoration bonded with particular adhesives after different surface pre-treatments

OBJECTIVE

To evaluate in vitro the shear bond strength of orthodontic molar tubes to composite restoration bonded with particular adhesives after different surface pre-treatments.

SETTING AND SAMPLE POPULATION

The sample population is 60 extracted molars.

MATERIALS AND METHODS

After the teeth were thermocycled, they were randomly divided into six groups according to the adhesive and various surface pre-treatments that had been applied. The surface pre-treatments included sandblasting with 50-μm aluminium oxide particles and roughening with diamond bur and 37% phosphoric acid. Transbond XT Adhesive Primer (3M Unitek) (TXT) and Assure Plus (Reliance Orthodontic Products) adhesives were used in the study. Following the application of the adhesives, the brackets were bonded to the surfaces of the teeth. Shear bond strength was measured using a universal testing machine. Data were analysed with one-way ANOVA and LSD tests (P = .05). The adhesive remnant index (ARI) was determined using a stereomicroscope. Data from the ARI scores were submitted to Pearson's chi-squared test (P = .05).

RESULTS

The highest shear bond strengths were obtained in the Assure Plus group 15.05 ± 3.72 MPa after sandblasting (P < .05). The lowest shear bond strengths were found in the TXT group (7.52 ± 2.89 MPa; P < .05). Sandblasting and bur pre-treatment for TXT and Assure Plus adhesives increased shear bond strength in both of them. There were no significant differences in the ARI scores between the groups (P > .05).

CONCLUSION

Sandblasting and roughening pre-treatment can increase the bond strength of teeth with composite restoration. Assure Plus is also more effective than conventional adhesive systems.

Effects of Novel versus Conventional Porcelain Surface Treatments on Shear Bond Strength of Orthodontic Brackets: A Systematic Review and Meta-Analysis

BACKGROUND

Despite the importance of identifying proper novel porcelain preparation techniques to improve bonding of orthodontic brackets to porcelain surfaces, and despite the highly controversial results on this subject, no systematic review or meta-analysis exists in this regard.

OBJECTIVE

To comparatively summarize the effects of all the available porcelain surface treatments on the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets (metal, ceramic, polycarbonate) bonded to feldspathic porcelain restorations. Search Methods. A search was conducted for articles published between January 1990 and February 2021 in PubMed, MeSH, Scopus, Web of Science, Cochrane, Google Scholar, and reference lists. Eligibility Criteria. English-language articles comparing SBS of feldspathic porcelain's surface preparation methods for metal/ceramic/polycarbonate orthodontic brackets were included. Articles comparing silanes/bonding agents/primers without assessing roughening techniques were excluded. Data Analysis. Studies were summarized and risk of bias assessed. Each treatment's SBS was compared with the 6 and 10 MPa recommended thresholds. Studies including comparator (HF [hydrofluoric acid] + silane + bonding) were candidates for meta-analysis. ARI scores were dichotomized. Fixed- and random-effects models were used and forest plots drawn. Egger regressions and/or funnel plots were used to assess publication biases.

RESULTS

Thirty-two studies were included (140 groups of SBS, 82 groups of ARI). Bond strengths of 21 studies were meta-analyzed (64 comparisons in 14 meta-analyses). ARIs of 12 articles were meta-analyzed (28 comparisons in 8 meta-analyses). Certain protocols provided bond strengths poorer than HF + silane + bonding: "abrasion + bonding, diamond bur + bonding, HF + bonding, Nd:YAG laser (1 W) + silane + bonding, CO₂ laser (2 W/2 Hz) + silane + bonding, and phosphoric acid + silane + bonding." Abrasion + HF + silane + bonding might act almost better than HF + silane + bonding. Abrasion + silane + bonding yields controversial results, being slightly (marginally significantly) better than HF + silane + bonding. Some protocols had controversial results with their overall effects being close to HF + silane + bonding: "Cojet + silane + bonding, diamond bur + silane + bonding, Er:YAG laser (1.6 W/20 Hz) + silane + bonding." Few methods provided bond strengths similar to HF + silane + bonding without much controversy: "Nd:YAG laser (2 W) + silane + bonding" and "phosphoric acid + silane + bonding" (in ceramic brackets). ARIs were either similar to HF + silane + bonding or relatively skewed towards the "no resin on porcelain" end. The risk of bias was rather low. Limitations. All the found studies were in vitro and thus not easily translatable to clinical conditions. Many metasamples were small.

CONCLUSIONS

The preparation methods HF + silane + bonding, abrasion + HF + silane + bonding, Nd:YAG (2 W) + silane + bonding, and phosphoric acid + silane + bonding (in ceramic brackets) might provide stronger bonds.

Comparison of feldspathic veneer surface treatments on ceramic bracket SBS, ARI and surface roughness after different debonding/polishing methods: An in vitro study

OBJECTIVES

To analyse, in vitro, surface properties and the shear bond strength after debonding and polishing procedures of ceramic brackets directly bonded to 0.3-0.5-mm thick feldspathic veneers.

MATERIALS AND METHODS

Fifty six feldspathic ceramic veneers samples (0.3 to 0.5-mm thick) were allocated into groups according to veneers surface treatment procedures: (S) glaze layer was retained; (SHF) hydrofluoric (HF) acid etch; (SOXA) Al2O3 sandblasting; and (SB) diamond burs roughening. Specimens were treated with silane Monobond N® and ceramic brackets bonded with Transbond XT^®. Shear bonding strength (SBS) was assessed with a universal testing machine and ARI evaluated under a stereomicroscopic coupled to a digital camera. Remaining bonding composite was removed using a porcelain polishing kit and surface roughness assessed with a stylus profilometer.

RESULTS

No statistically significant differences were identified for SBS among the study groups (S, SHF, SOXA and SB) (P>0.05). The majority of the specimens presented ARI scores 3 and 2 (P>0.05). All of the study groups presented increased surface roughness after debonding and polishing procedures (P<0.05), with significant greater values observed in SB group (RaF: 1.27±0.41; RzF: 6.23±1.82), (P<0.05).

CONCLUSIONS

Surface treatment with hydrofluoric acid etch, Al₂O₃ sandblasting and diamond bur did not enhance SBS of orthodontic brackets bonded to ceramic veneers. Ceramic surfaces treated with diamond burs presented significantly increased roughness after adhesive removal.

Orthodontic Attachment Adhesion to Ceramic Surfaces

Ceramic materials are constantly evolving, achieving good functionality and aesthetics. Bonding to ceramics may be difficult because of high toxicity procedures and risk of surface damage. The review aims to answer several research questions: Is there a golden standard for bonding to ceramic? Are there adhesives or types of photopolymerization lamps that produce a higher bond strength on certain types of ceramics rather than others? Articles focusing on the bonding process of orthodontic attachments to ceramic surfaces searched in Pubmed, Medline and Embase, published between 1990 and 2018 were revised. Exclusions concerned bonding to non-ceramic surfaces, bonding to ceramic surfaces that are not destined for orthodontics or laser usage. Forty-nine articles that matched the inclusion criteria were researched. The following categories of original research articles were compared and discussed: metallic brackets bonding to ceramic surfaces, ceramic brackets to ceramic surfaces, bonding to new types of ceramics, such as zirconia, lithium disilicate, different photopolymerisation devices used on bonding to ceramics. Some types of adhesive may achieve minimal bond strength (6-8 MPa) even on glazed ceramic. Ceramic surface preparation may be done by sandblasting or hydrofluoric acid (60s application and 9.6%) with generally similar results. Studies rarely show any statistical difference and there are reduced number of samples in most studies. Ceramic brackets show better adhesion to ceramic surfaces and the same bonding protocol is advised. A higher bond strength may lead to ceramic surface. Few studies focus on newer types of ceramics; additional research is necessary. There is no clear evidence that a certain type of photopolymerization device produces higher shear bond strength values.

Influence of photodynamic therapy and different conventional methods on conditioning of lithium di silicate ceramics bonded to metallic brackets: An assessment of bond strength

AIM

The aim of the current study was to assess the effect of different conditioning methods on Lithium di silicate (LDC) employing conventional and contemporary regimes bonded to metallic brackets.

MATERIAL AND METHODS

70 discs of LDC were prepared and polished to attain smooth surface. Samples were allocated into seven groups according to ceramic surface conditioning. Group 1 surface treated with Er-YAG laser and saline (S), Group 2 PDT using MBP + S, Group 3 H F + S (control), Group 3 HF (Hydrofluoric acid) + saline, Group 4 HF (Hydrofluoric acid) + ultrasonic bath (UB) + S, Group 5 sand blasting the glass ceramic surface with 120 um Al₂O₃, Group 6 LDC surface conditioned with SECP(Etch and Prime) and Group 7 ECL(Laser) + S on was irradiated on LDC. Both chemical and mechanical surface treatments of LDC were followed by placement of metallic brackets. Samples were arranged in universal testing machine for shear bond strength (SBS) testing. Bond failure of brackets were assessed using ARI. To assess and compare the mean and standard deviations (SD) among experimental groups analysis of variance (ANOVA) was employed. All treatment combination means were compared using the post hoc Tukey's multiple comparison test at a significance level of (p ≤ 0.05).

RESULTS

SBS values of Group 2 H F acid + S displayed highest bond durability (22.28 ± 1.09 MPa). Whereas, specimens in Group 4 surface treated with 120 μm Al₂O₃ displayed lowest SBS scores (11.81 ± 0.55 MPa) and these bond scores were comparable to PDT using MBP + S (12.54 ± 1.09 MPa) (p > 0.05). LDC surface treated by ECL + S (21.11 ± 3.85 MPa), HF + UB + S (19.28 ± 0.52 MPa) exhibited results comparable to HF acid + S (p > 0.05).

CONCLUSION

LDC conditioned with HFS still remains as gold standard. Use of PDT for surface treatment of LDC and bonded to metallic bracket is not recommended as it results in decreased bond durability. Use of ECL-S and HF + UB + S has a potential to be used alternatively to HFS for LDC conditioning.

Comparison of lithium disilicate-reinforced glass ceramic surface treatment with hydrofluoric acid, Nd:YAG, and CO2 lasers on shear bond strength of metal brackets

OBJECTIVES

To evaluate and compare the effects of different surface conditioning methods of lithium disilicate-reinforced ceramic on shear bond strength (SBS) of metallic brackets.

MATERIALS AND METHODS

Thirty-six lithium disilicate ceramic blocks mounted in acrylic resin blocks were assigned to 3 groups (n = 12): 9.6% hydrofluoric acid (HF); neodymium-doped yttrium aluminium garnet (Nd:YAG) laser; and carbon dioxide (CO₂) laser. The glass ceramic surfaces were primed with a silane, and the brackets were bonded using a light-cured composite resin. SBS test was carried out in a universal testing machine at 0.5 mm/min crosshead speed until the brackets were debonded. The remaining adhesive was evaluated under a stereomicroscope in terms of the adhesive remnant index (ARI). The surface hardness was determined with a 100-gr force using a microhardness tester. Glass ceramic surface changes were evaluated using the scanning electron microscope. One-way ANOVA and post hoc Tamhane tests were used to compare microhardness values, and Kruskal-Wallis and Mann-Whitney U tests were used to analyze SBS values and ARI.

RESULTS

The median and interquartile range of SBS values in 3 groups were 6.48 (1.56-15.18), 1.26 (0.83-1.67), and 0.99 MPa (0.70-2.10), respectively. Microhardness analysis revealed significant differences between the CO₂ laser and intact porcelain groups (P = 0.003), without significant differences between the other groups. Group 1 exhibited the highest ARI.

CONCLUSION

Neither CO₂ nor Nd:YAG lasers resulted in adequate surface changes for bonding of brackets on ceramics compared with the samples conditioned with HF. CO₂ laser decreased the microhardness of ceramics.

CLINICAL RELEVANCE

Surface conditioning with HF resulted in clinically acceptable SBS values.

Orthodontic Bonding: Review of the Literature

BACKGROUND

Patients seeking orthodontic treatment are increasing, and clinicians often have to place brackets on various surfaces aside from enamel. It is crucial to know what materials or instruments are required to bond brackets to each surface.

OBJECTIVE

This study aims to serve as a clinical guideline for the safest and most effective approaches taken to condition various surfaces for bonding to orthodontic brackets and provide background knowledge on the subject.

MATERIALS AND METHODS

PubMed and EBSCO databases were searched, along with the use of Google Scholar search engine, to obtain relevant articles published in English in peer-reviewed journals, from 1955 to 2020. Keywords used were Shear bond strength; Orthodontic bracket; Base design; Etching; Sandblasting; Laser; Conditioning; Enamel; Ceramic; Porcelain; Gold; Amalgam; Composite.

CONCLUSION

Even though orthophosphoric acid is the most widely used enamel conditioning agent, laser etching should be considered to avoid enamel decalcification. Hydrofluoric acid is the current standard for ceramic conditioning; however, its use intraorally should be minimized due to its toxicity. Orthophosphoric acid, CoJet-Sand air abrasion, and laser etching are viable alternatives for conditioning ceramic. Monobond Etch & Prime is toxic and should not be used intraorally. Composite can be conditioned by bur roughening, and the use of ceramic brackets is recommended. Amalgam and gold surfaces can be conditioned adequately by air abrasion. Despite the claims of many authors, the maximum shear forces that orthodontic brackets are subjected to are not 6-8 mega pascal (MPa). Further investigation is required in that regard. More in vivo studies need to be performed to confirm the in vitro results.

Lithium di silicate ceramic surface treated with Er,Cr:YSGG and other conditioning regimes bonded to orthodontic bracket

Aim

To assess bond integrity and modes of failure of metallic brackets to lithium disilicate ceramics (LDC) conditioned with Er,Cr:YSGG laser (ECL).

Material and methods

Sixty LDC were arbitrarily allocated into six groups (n = 15) according to the type of ceramic surface conditioning treatment. Group 1 surface treated with silane (S) only, group 2 surface etched with hydrofluoric acid (HF)+ S, group 3 surface conditioned with HF+ ultrasonic bath (UB)+ S, group 4 sand blasting (SB) of glass ceramic surface with 50 µm Al₂O₃, group 5 surface conditioned with self-etch ceramic primer (SECP) and in group 6 surface treated with ECL + S. After conditioning, the specimens were positioned in a universal testing device for shear bond strength (SBS) testing. Adhesive Remnant Index (ARI) was used to determine sites of bond failure. Among experimental groups analysis of variance (ANOVA) and Tukey multiple comparison test was used at a significance level of (p < 0.05).

Results

The highest SBS values were observed in group 3 HF+ UB + S (18.21 ± 1.241) and the lowest SBS values were displayed group 1 surface treated with S only (5.21 ± 0.23). Specimens surface conditioned in group 2 with HF+ S (17.85 ± 1.25), group 3 HF+ UB + S (18.21 ± 1.241) and group 6 ECL + S (17.09 ± 1.114) unveiled comparable SBS values (p > 0.05).

Conclusion

LDC conditioned with ECL at (4.5 W and 30 Hz) has a potential to be used in clinical settings alternate to HF acid.

In vitro comparison of shear bond strengths of ceramic orthodontic brackets with ceramic crowns using an aluminium oxide air abrasion etchant

OBJECTIVE

The aim of this study was to determine if there are differences between the shear bond strengths of 3 types of ceramic brackets when bonded to different ceramic substrates using an aluminium oxide air abrasion etchant protocol.

MATERIALS AND METHODS

Substrate groups consisting of thirty-six lithium disilicate (e.max® CAD) samples and thirty-six lithium silicate infused with zirconia (CELTRA® DUO) samples were fabricated to replicate the facial surface of a left maxillary central incisor. The surface of all samples was prepared with an aluminium oxide air abrasion etchant protocol. Each substrate group was split into three test groups (n=12). Each test group was bonded using a different brand of ceramic orthodontic bracket. Shear bond strength (SBS) testing was conducted and the mean SBS values for each group were calculated and recorded in MPa. An Adhesive Resin Index (ARI) score was also assigned to each sample to assess the location of bond failure.

RESULTS

Mean SBS of the e.max® CAD groups were significantly less than the CELTRA® DUO groups. Symetri brackets showed significantly higher shear bond strengths to both substrates than both of the other brackets tested. ARI scores of the e.max® CAD groups were significantly less than the CELTRA® DUO groups.

CONCLUSION

The Symetri bracket was the only bracket that was effective for both substrates (mean SBS>6mPa). The Etch Master protocol does not appear effective for e.max® CAD.

Shear bond strength of orthodontic brackets bonded to a new all-ceramic crown composed of lithium silicate infused with zirconia: An in vitro comparative study

AIM

This study sought to determine whether a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets is achievable to CAD/CAM (Computer-Aided Design/Manufacturing) lithium silicate infused with zirconia and whether a chemical pre-treatment bonding protocol produced a higher shear bond strength.

MATERIALS AND METHODS

Twenty lithium silicate infused with zirconia (CELTRA® DUO) samples, twenty zirconia samples, and twenty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular left first molar. The samples were split into two test groups, one of which received a chemical pre-treatment protocol (hydrofluoric acid etch). Shear bond strength testing was conducted and the mean, maximum, minimal, and standard deviation SBS values for each were calculated and recorded in MPa. An Adhesive Resin Index (ARI) score was also assigned to each sample to assess the mode of bond failure.

RESULTS

SBS of the lithium silicate infused with zirconia groups were significantly less than the chemically pre-treated lithium disilicate group, however both materials, when chemical pre-treatment protocol was used, were not statistically different than the enamel control.

CONCLUSIONS

Orthodontic bonding to lithium silicate infused with zirconia yielded a weaker shear bond strength than bonding to traditional lithium disilicate, however, when the surface was pre-treated with hydrofluoric acid etch it provides a bond strength that is within an acceptable clinical range.

Airborne-particle abrasion; searching the right parameter

Background/purpose

Air-particle abrasion process used to increase surface roughness in order to increase metal-ceramic bond strength varies in each study. This study aims to optimize the air-particle abrasion protocol.

Material and methods

820 cylindrical nickel-chrome specimens divided equally into 82 groups (n:10). The specimens' s surfaces were air-particle abraded with 50, 110, 250 μm Al₂O₃ at 25, 50,75 psi for 10, 20, 30 s at a distance of 10, 20, 30 mm. To determine the surface roughness, profilometer and atomic force microscope were used. Veneering ceramic was fired onto the specimens and shear bond tests were performed with a universal testing machine. Statistical analyzed were performed using analysis of variance (Kolmogorov–Smirnov).

Results

The difference of surface roughness between all groups were statistically significant (P < .05). The highest surface roughness value was measured in 110 μm, 75 psi, 20 mm and 30 s. The higher bond strength values were obtained in 110 μm, 75 psi groups and no statistically significant difference was observed within each group.

Conclusion

While all the air-particle abrasion parameters were effective on surface roughness, only the pressure and grain size make statistically significant difference on shear bond strength.

Biomechanical evaluation between orthodontic attachment and three different materials after various surface treatments: A three-dimensional optical profilometry analysis

OBJECTIVES

To determine the best bonding method of orthodontic attachment among monolithic zirconia, feldspathic porcelain, hybrid porcelain, and the impact of surface-conditioning methods using a three-dimensional optical profilometer after debonding.

MATERIALS AND METHODS

56 feldspathic porcelain, 56 monolithic zirconia, and 56 hybrid porcelain samples were divided into four surface treatment subgroups: (1) hydrofluoric (HF) acid etch + silane, (2) Al₂O₃ sandblasting + silane, (3) silicoating (SiO₂), and (4) diamond bur + silane. The specimens were tested to evaluate shear bond strength (SBS). Residual composite was removed after debonding. Three-dimensional white-light interferometry was used to obtain quantitative measurements on surface roughness.

RESULTS

The highest SBS value was found for the HF acid-etched feldspathic porcelain group. The average surface roughness values were significantly higher in all material groups in which diamond bur was applied, while roughening with Cojet provided average surface roughness values closer to the original material surface.

CONCLUSIONS

Variations in structures of the materials and roughening techniques affected the SBS and surface roughness findings.

Efficacy of phototherapy with different conventional surface treatments on adhesive quality of lithium disilicate ceramics

AIM

The aim of the present study was to evaluate shear bond strength (SBS) of LDC and resin composite in combination with phototherapy and different ceramic surface treatments.

MATERIALS AND METHOD

Forty Lithium Disilicate Glass Ceramic (LDC) disks measuring (4 × 4 x 9 mm) were fabricated. The specimens were randomly divided into four groups (n = 10 each) according to the surface treatment. Group 1 H F + Silane (Control); Group 2 HF + Ultrasonic bath + Silane; Group 3 SECP (Self etch ceramic primer) and Group 4 phototherapy (Er, Cr: YSGG) + Silane. On each ceramic disk a resin build-up was done. For SBS the specimens were subjected to increasing load with a transversal velocity of 1 ml/min on a universal testing machine on a ceramic resin interface. Failure mode was evaluated using digital microscope. The failure modes were divided into adhesive, cohesive and admixed interface. Data through bond strength testing was tabulated using statistical program for social science (SPSS). Means and standard deviations were compared using analysis of variance and Tukey's post hoc test (p < 0.05).

RESULTS

The maximum and minimum bond strength was observed in group 2 [19.58(1.011)] and group 1 [17.14(1.122)] respectively. The bond strength among experimental group 1 [17.14 (1.122)] and group 4 [17.48(1.145)] were found to be comparable. Specimens in Group 2 displayed significantly higher bond strength among all experimental groups. Commonly adhesive failure mode was observed in the present study, with an incidence of 60%, 100% and 70% in groups 1,2 and 3 correspondingly.

CONCLUSION

Phototherapy using laser at frequency 30 Hz and 4.5 W can be used as a surface conditioner for LDC alternate to HF acid. Conditioning of LDC using Self-etch ceramic primer showed better SBS outcomes as compared to phototherapy (Er, Cr: YSGG laser).

Bonding Strength of Orthodontic Brackets on Porcelain Surfaces Etched by Er:YAG Laser

OBJECTIVE

To evaluate the effect of erbium: yttrium aluminium garnet laser conditioning bond strength of orthodontic brackets on porcelain surfaces.

BACKGROUND

There are few studies that evaluate the effect of Er:YAG laser about orthodontic bonding on porcelain surface. The efficacy of Er:YAG laser in porcelain conditioning is controversial.

MATERIALS AND METHODS

Ninety ceramic specimens were randomly divided into five group, group A: etched with hydrofluoric (HF) acid; group B and C: etched with an energy parameter of 250 mJ, 20 Hz and 300 mJ, 20 Hz by Er:YAG laser instrument; group D and E: etched with an energy parameter of 250 mJ, 20 Hz and 300 mJ, 20 Hz of Er:YAG laser with HF etching. Afterward, two samples selected randomly from each group were evaluated by scanning electron microscopy. Brackets were bonded on the remaining samples, which were stored in distilled water and thermocycled. Each group was measured by shear bond strength (SBS), tensile bond strength (TBS), porcelain fracture index (PFI), and adhesive remnant index (ARI) calculation. Data were statistically analyzed using SPSS software.

RESULTS

The SBS and TBS in group E were the largest. Comparing SBS and TBS of HF group and other Er:YAG laser group, there were statistically significant difference (p < 0.05). PFI was significantly higher in shear force group than the tensile force group. HF group had higher ARI score than the other groups.

CONCLUSIONS

Porcelain surfaces etched by 250 mJ, 20 Hz of Er:YAG laser combined with HF acid can get enough bond strength and have lower porcelain fracture rate for orthodontic bracket bonding.

Assessment the Bond Strength of Ceramic Brackets to CAD/CAM Nanoceramic Composite and Interpenetrating Network Composite after Different Surface Treatments

Adult orthodontics may confront problems related to the bonding performance of orthodontic brackets to new generation restorative materials used for crown or laminate restorations. The aim of the present study was to investigate the shear bond strength of ceramic brackets to two new generation CAD/CAM interpenetrating network composite and nanoceramic composite after different surface treatments. Er,Cr:YSGG Laser, hydrofluoric acid (9%), sandblasting (50 μm Al₂O₃), and silane were applied to the surfaces of 120 CAD/CAM specimens with 2 mm thickness and then ceramic brackets were bonded to the treated surfaces of the specimens. Bond strength was evaluated using the shear bond strength test. According to the results, CAD/CAM block types and surface treatment methods have significant effects on shear bond strength. The lowest bond strength values were found in the specimens treated with silane (3.35 ± 2.09 MPa) and highest values were found in the specimens treated with sandblast (8.92 ± 2.77 MPa). Sandblasting and hydrofluoric acid surface treatment led to the most durable bonds for the two types of CAD/CAM blocks in the present study. In conclusion, different surface treatments affect the shear bond strength of ceramic brackets to CAD/CAM interpenetrating network composite and nanoceramic composite. Among the evaluated treatments, sandblasting and hydrofluoric acid application resulted in sufficient bonding strength to ceramic brackets for both of the CAD/CAM materials.

Shear bond strength of ceramic brackets bonded to surface-treated feldspathic porcelain after thermocycling

Purpose:

The aim of this study was to evaluate the effect of six different surface conditioning methods on the shear bond strength of ceramic brackets bonded to feldspathic porcelain.

Materials and methods:

A total of 60 feldspathic porcelain disks were fabricated and divided into six subgroups including 10 specimens in each. Specimens were first treated one of the following surface conditioning methods, namely, 37% phosphoric acid (G-H3PO4), 9.4% hydrofluoric acid (G-HF), grinding with diamond burs (G-Grinding), Nd:YAG laser (G-Nd:YAG), Airborne-particle abrasion (G-Abrasion). Specimens were also coated with silane without surface treatment for comparison (G-Untreated). A total of 60 ceramic brackets were bonded to porcelain surfaces with a composite resin and then subjected to thermocycling 2500× between 5°C and 55°C. The shear bond strength test was carried out using a universal testing device at a crosshead speed of 0.5 mm/min. Failure types were classified according to the adhesive remnant index. Analysis of variance and Tukey tests were used for statistical analysis (α = 0.05). Microstructure of untreated and surface-treated specimens was investigated by scanning electron microscopy.

Results:

Using G-Abrasion specimens resulted in the highest shear bond strength value of 8.58 MPa for feldspathic porcelain. However, the other specimens showed lower values: G-Grinding (6.51 MPa), G-Nd:YAG laser (3.37 MPa), G-HF (2.71 MPa), G-H3PO4 (1.17 MPa), and G-Untreated (0.93 MPa).

Conclusion:

Airborne-particle abrasion and grinding can be used as surface treatment techniques on the porcelain surface for a durable bond strength. Hydrofluoric acid and phosphoric acid etching methods were not convenient as surface treatment methods for the feldspathic porcelain.

Effect of Silane Heat Treatment by Laser on the Bond Strength of a Repair Composite to Feldspathic Porcelain

PURPOSE

Ceramic restoration fracture may occur in the oral cavity. Intraoral repair of fractured porcelain could be advantageous to both patient and dentist. The aim of this study was to evaluate the effect of heat treatment of the silane coupling agent by Er:YAG and CO₂ lasers on the microshear bond strength of a repair composite to feldspathic porcelain.

MATERIALS AND METHODS

Sixty ceramic blocks were prepared and randomly divided into six groups (n = 10): (i) HF + silane (HS); (ii) silane + CO₂ laser (SC); (iii) CO₂ laser + silane (CS); (iv) silane + Er:YAG laser (SE); (v) Er:YAG laser + silane (ES); (vi) bur + HF + silane (BuHS). An adhesive resin was applied to the prepared ceramic surfaces and light-cured. Two transparent plastic tubes were placed perpendicularly to each ceramic block. The composite resin was then placed on the treated ceramic surface and light-cured for 40 seconds. The bonded blocks were stored in distilled water at 37°C for 24 hours and subjected to 3000 thermocycles. Microshear bond strength (μSBS) tests were performed using a wire and loop method. Data were analyzed using one-way ANOVA and Duncan's multiple range tests (p ≤ 0.05).

RESULTS

The comparison of the mean μSBS values showed no significant differences between the ES and HS groups (p = 0.914). On the other hand, the specimens in these groups exhibited significantly higher bond strengths than those in the other groups (p < 0.01). The mean μSBS of the BuHS group was statistically similar to that of CS and SE groups (p > 0.05). The μSBS for the SC group was significantly lower than that of the other groups (p < 0.01), with the exception of the CS group (p = 0.674).

CONCLUSIONS

Treatment with Er:YAG laser prior to silane application can be as effective as HF etching. Heat treatment of silane by CO₂ or Er:YAG lasers does not improve the bond strength between feldspathic porcelain and composite resin.

Shear Bond Strength of Al₂O₃ Sandblasted Y-TZP Ceramic to the Orthodontic Metal Bracket

As the proportion of adult orthodontic treatment increases, mainly for aesthetic reasons, orthodontic brackets are directly attached to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations. This, study analyzed the shear bond strength (SBS) between various surface treated Y-TZP and orthodontic metal brackets. The Y-TZP specimens were conditioned by 110 μm Al₂O₃ sandblasting, or sandblasting followed by coating with one of the primers (silane, MDP, or an MDP-containing silane primer). After surface treatment, the orthodontic metal bracket was bonded to the specimen using a resin cement, and then 24 h storage in water and thermal cycling (5000 cycles, 5-55 °C), SBS was measured. Surface roughness was analyzed for surface morphology, and X-ray photoelectron spectroscopy (XPS) was employed for characterization of the chemical bond between the Y-TZP and the MDP-based primers (MDP, MDP containing silane primer). It was found that after surface treatment, the surface roughness of all groups increased. The groups treated with 110 μm Al₂O₃ sandblasting and MDP, or MDP-containing silane primer showed the highest SBS values, at 11.92 ± 1.51 MPa and 13.36 ± 2.31 MPa, respectively. The SBS values significantly decreased in all the groups after thermal cycling. Results from XPS analysis demonstrated the presence of chemical bonds between Y-TZP and MDP. Thus, the application of MDP-based primers after Al₂O₃ sandblasting enhances the resin bond strength between Y-TZP and the orthodontic metal bracket. However, bonding durability of all the surface-treated groups decreased after thermal cycling.

Does acid etching morphologically and chemically affect lithium disilicate glass ceramic surfaces?

BACKGROUND

This study evaluated the surface morphology, chemical composition and adhesiveness of lithium disilicate glass ceramic after acid etching with hydrofluoric acid or phosphoric acid.

METHODS

Lithium disilicate glass ceramic specimens polished by 600-grit silicon carbide paper were subjected to one or a combination of these surface treatments: airborne particle abrasion with 50-μm alumina (AA), etching with 5% hydrofluoric acid (HF) or 36% phosphoric acid (Phos), and application of silane coupling agent (Si). Stainless steel rods of 3.6-mm diameter and 2.0-mm height were cemented onto treated ceramic surfaces with a self-adhesive resin cement (Clearfil SA Cement). Shear bond strengths between ceramic and cement were measured after 24-hour storage in 37°C distilled water.

RESULTS

SEM images of AA revealed the formation of conventional microretentive grooves, but acid etching with HF or Phos produced a porous surface. Bond strengths of AA+HF+Si (28.1 ± 6.0 MPa), AA+Phos+Si (17.5 ± 4.1 MPa) and HF+Si (21.0 ± 3.0 MPa) were significantly greater than those of non-pretreated controls with Si (9.7 ± 3.7 MPa) and without Si (4.1 ± 2.4 MPa) (p&lt;0.05). In addition, HF etching alone (26.2 ± 7.5 MPa) had significantly higher bond strength than AA alone (11.5 ± 4.0 MPa) (p&lt;0.05). AA+HF, AA+Phos and HF showed cohesive failures.

CONCLUSIONS

Etching with HF or Phos yielded higher bond strength between lithium disilicate glass ceramic and self-adhesive resin cement without microcrack formation.

Surface topography and bond strengths of feldspathic porcelain prepared using various sandblasting pressures

OBJECTIVE

The purpose of this study was to determine the bond strength of composite resin to feldspathic porcelain and its surface topography after sandblasting at different pressures.

METHODS

In this in vitro study, 68 porcelain disks were fabricated and randomly divided into four groups of 17. The porcelain surface in group 1 was etched with hydrofluoric acid. Groups 2, 3, and 4 were sandblasted at 2, 3 and 4 bars pressure, respectively. Surface topography of seven samples in each of the four groups was examined by a scanning electron microscope (SEM). The remaining 40 samples received the same silane agent, bonding agent, and composite resin and they were then subjected to 5000 thermal cycles and evaluated for shear bond strength. Data were analyzed using one-way anova. The mode of failure was determined using stereomicroscope and SEM.

RESULTS

The highest shear bond strength was seen in group 4. however, statistically significant differences were not seen between the groups (P = 0.780). The most common mode of failure was cohesive in porcelain. The SEM showed different patterns of hydrofluoric acid etching and sandblasting.

CONCLUSION

Increasing the sandblasting pressure increased the surface roughness of feldspathic porcelain but no difference in bond strength occurred.

Influence of tooth brushing on adhesion strength of orthodontic brackets bonded to porcelain

BACKGROUND

Adhesive resin composite, which is used to bond orthodontic bracket to tooth surface is exposed to the influence of wear by tooth brushing and wear may influence loosening of the bracket.

OBJECTIVE

The aim of this study was to evaluate in vitro the effect of tooth brushing on the adhesion strength of orthodontic brackets bonded to surface treated porcelain.

METHOD

A total of 90 glazed porcelain fused to metal facets (PFM) were randomly assigned into 3 groups according to the surface treatment to be received. Group 1 was conditioned with hydrofluoric acid (HF), group 2 conditioned with grit-blasting (GB) and group 3 conditioned with tribochemical silica coating (RC). The groups were evaluated for surface roughness (Ra) before and after surface treatment. Next, 15 samples from each group were subjected to brushing and remaining 15 samples served as the baseline (n=15). Adhesion strength (shear bond strength)was recorded using a universal testing machine. Data collected were analyzed by ANOVA and Tukey's multiple comparison post hoc analysis.

RESULTS

Tooth brushing decreased the bond strength in all groups. The highest adhesion strength (baseline and after brushing) was observed in group 3 (26.8 ± 1.77 MPa and 23.57 ± 1.02 MPa) and the lowest was found in group 1 (9.6 ± 1.5 MPa and 5.87 ± 0.77 MPa). Group 3 specimens exhibited the highest Ra (1.24 ± 0.08).

CONCLUSION

It was found that tooth brushing of the exposed adhesive resin composite at the bracket-bonding substrate interface lowers the bonding strength regardless of the surface treatment of the substrate.

Bond strength of metal brackets bonded to a silica-based ceramic with light-cured adhesive : Influence of various surface treatment methods

OBJECTIVE

The purpose of this work was to evaluate the effects of several surface treatment methods on the shear bond strengths of metal brackets bonded to a silica-based ceramic with a light-cured adhesive.

MATERIALS AND METHODS

Silica-based ceramic (IPS Classic(®)) with glazed surfaces was cut into discs that were used as substrates. A total of 80 specimens were randomly divided into four groups according to the method used: 9.6 % hydrofluoric acid (group 1), 9.6 % hydrofluoric acid (HF) + silane coupling agent (group 2), sandblasting (aluminum trioxide, 50 μm) + silane (group 3), and tribochemical silica coating (CoJet™ sand, 30 μm) + silane (group 4). Brackets were bonded to the treated specimens with a light-cure adhesive (Transbond XT, 3 M Unitek). Shear bond strength was tested after bracket bonding, and the Adhesive Remnant Index (ARI) scores were quantified after debonding.

RESULTS

Group 4 showed the highest bond strength (12.3 ± 1.0 MPa), which was not significantly different from that of group 3 (11.6 ± 1.2 MPa, P > 0.05); however, the bond strength of group 4 was substantially higher than that of group 2 (9.4 ± 1.1 MPa, P < 0.05). The shear bond strength of group 1 (3.1 ± 0.6 MPa, P< 0.05) was significantly lower than that of the other groups.

CONCLUSION

Shear bond strengths exceeded the optimal range of ideal bond strength for clinical practice, except for the isolated HF group. HF acid etching followed by silane was the best suited method for bonding on IPS Classic(®). Failure modes in the sandblasting and silica-coating groups revealed signs of damaged ceramic surfaces.

Light transmittance and surface roughness of a feldspathic ceramic CAD-CAM material as a function of different surface treatments

BACKGROUND

The aim of the present study was to determine the effect of different surface treatments on light transmission of aesthetic feldspathic ceramics used in CAD-CAM chairside restorations.

METHODS

Forty eight feldspatic ceramic test specimens were prepared from prefabricated CAD-CAM blocks by using a slow speed diamond saw. Test specimens were prepared and divided into 4 groups (n = 12). In the control group, no surface treatments were applied on the feldspathic ceramic surfaces. In the hydrofluoric acid group, the bonding surfaces of feldspathic ceramics were etched with 9.5 % hydrofluoric acid. In the sandblasting group the feldspathic ceramic surfaces were air-abraded with 30-μm alumium oxide (Al2O3) particles and Er:YAG laser was used to irradiate the ceramic surfaces. The incident light power given by the LED device and the transmitted light power through each ceramic sample was registered using a digital LED radiometer device. Each polymerization light had a light guide with 8-mm-diameter tips. Light transmission of feldspathic ceramic samples was determined by placing it on the radiometer and irradiating the specimen for 10 s at the highest setting for each light polymerization. All specimens were coated with gold using a sputter coater and examined under a field emission scanning electron microscope. Surface roughness measurement each group were evaluated with 3D optical surface and tactile profilometers.

RESULTS

One-way ANOVA test results revealed that both surface conditioning method significantly affect the light transmittance (F:412.437; p < 0.001) and the surface roughness values (F:16.386; p < 0.001). Al2O3 and Er-YAG laser application reduced the light transmission significantly (p < 0.05).

CONCLUSIONS

The laser and Al2O3 applications reduced the light transmission of 1.5 mm thickness feldspathic ceramic material below the value of 400 mW/cm(2) which is critical limit for safe polymerization.

Resin bonding of metal brackets to glazed zirconia with a porcelain primer

Objective

The aims of this study were to compare the shear bond strength between orthodontic metal brackets and glazed zirconia using different types of primer before applying resin cement and to determine which primer was more effective.

Methods

Zirconia blocks were milled and embedded in acrylic resin and randomly assigned to one of four groups: nonglazed zirconia with sandblasting and zirconia primer (NZ); glazed zirconia with sandblasting, etching, and zirconia primer (GZ); glazed zirconia with sandblasting, etching, and porcelain primer (GP); and glazed zirconia with sandblasting, etching, zirconia primer, and porcelain primer (GZP). A stainless steel metal bracket was bonded to each target surface with resin cement, and all specimens underwent thermal cycling. The shear bond strength of the specimens was measured by a universal testing machine. A scanning electron microscope, three-dimensional optical surface-profiler, and stereoscopic microscope were used to image the zirconia surfaces. The data were analyzed with one-way analyses of variance and the Fisher exact test.

Results

Group GZ showed significantly lower shear bond strength than did the other groups. No statistically significant differences were found among groups NZ, GP, and GZP. All specimens in group GZ showed adhesive failure between the zirconia and resin cement. In groups NZ and GP, bonding failed at the interface between the resin cement and bracket base or showed complex adhesive and cohesive failure.

Conclusions

Porcelain primer is the more appropriate choice for bonding a metal bracket to the surface of a full-contour glazed zirconia crown with resin cement.

Four chemical methods of porcelain conditioning and their influence over bond strength and surface integrity

OBJECTIVE:

To assess four different chemical surface conditioning methods for ceramic material before bracket bonding, and their impact on shear bond strength and surface integrity at debonding.

METHODS:

Four experimental groups (n = 13) were set up according to the ceramic conditioning method: G1 = 37% phosphoric acid etching followed by silane application; G2 = 37% liquid phosphoric acid etching, no rinsing, followed by silane application; G3 = 10% hydrofluoric acid etching alone; and G4 = 10% hydrofluoric acid etching followed by silane application. After surface conditioning, metal brackets were bonded to porcelain by means of the Transbond XP system (3M Unitek). Samples were submitted to shear bond strength tests in a universal testing machine and the surfaces were later assessed with a microscope under 8 X magnification. ANOVA/Tukey tests were performed to establish the difference between groups (α= 5%).

RESULTS:

The highest shear bond strength values were found in groups G3 and G4 (22.01 ± 2.15 MPa and 22.83 ± 3.32 Mpa, respectively), followed by G1 (16.42 ± 3.61 MPa) and G2 (9.29 ± 1.95 MPa). As regards surface evaluation after bracket debonding, the use of liquid phosphoric acid followed by silane application (G2) produced the least damage to porcelain. When hydrofluoric acid and silane were applied, the risk of ceramic fracture increased.

CONCLUSIONS:

Acceptable levels of bond strength for clinical use were reached by all methods tested; however, liquid phosphoric acid etching followed by silane application (G2) resulted in the least damage to the ceramic surface.

Nd:YAG Laser to obtain Irregularities on the Inner Surface of Porcelain

AIM

The aim of this study was to evaluate the inner surface of two ceramic systems: IPS Empress II (Ivoclar Vivadent, Germany) and In-Ceram Alumina (Vita Zahnfabrick, Germany) submitted to surface treatments, especially by Nd:YAG laser.

MATERIALS AND METHODS

Fifty samples were prepared in pellet form for each ceramic system according to manufacturers' specifications. The samples were stored at room temperature and then be subjected to surface treatment: without treatment (T0) (control), hydrofluoric acid-etched (T1), hydrofluoric acid-etched associated with the airborne particle-abraded (T2); CoJet system (T3), Nd:YAG laser (T4). The data were performed the statistical analysis by ANOVA and Tukey's test (p < 0.001).

RESULTS

The group control (T0) of the ceramics, the analysis showed the lowest roughness values; for the System Alumina In-Ceram, treatment with hydrofluoric acid (T1), associated with hydrofluoric acid and airborne particle-abraded (T2) and Nd:YAG laser (T4), had no statistically significant difference, whereas for the IPS Empress System II treatment with hydrofluoric acid (T1) and hydrofluoric acid associated with airborne particle-abraded (T2), had no statistically significant difference between the system and also CoJet (T3) and hydrofluoric acid associated with the airborne particle-abraded (T2). Photomicrographs of scanning electron microscopy showed different characteristics to the treatments for each ceramic system.

CONCLUSION

The IPS Empress II had the appearance of favoring the retention when treated with hydrofluoric acid, as well as its association with the airborne particle-abraded. Uncertainty in Alumina, treatment with hydrofluoric acid associated with the airborne particle-abraded and CoJet system and provided a surface with irregularities. With respect to the laser further studies should be performed for parameters that are ideal for your application.

CLINICAL RELEVANCE

The ceramic restorations are attractive due of their excellent esthetics and the ability to stay for long periods. However, the retention of ceramic requires further study.

Effect of Ti:sapphire laser on shear bond strength of orthodontic brackets to ceramic surfaces

BACKGROUND AND OBJECTIVES

With increasing demand for orthodontic treatments in adults, orthodontists continue to debate the optimal way to prepare ceramic surfaces for bonding. This study evaluated the effects of a Ti:sapphire laser on the shear bond strength (SBS) of orthodontic brackets bonded to two ceramic surfaces (feldspathic and IPS Empress e-Max) and the results were compared with those using two other lasers (Er:YAG and Nd:YAG) and 'conventional' techniques, i.e., sandblasting (50 µm) and hydrofluoric (HF) acid.

MATERIALS AND METHODS

In total, 150 ceramic discs were prepared and divided into two groups. In each group, the following five subgroups were prepared: Ti:sapphire laser, Nd:YAG laser, Er:YAG laser, sandblasting, and HF acid. Mandibular incisor brackets were bonded using a light-cured adhesive. The samples were stored in distilled water for 24 hours at 37°C and then thermocycled. Extra samples were prepared and examined using scanning electron microscopy (SEM). SBS testing was performed and failure modes were classified. ANOVA and Tukey's HSD tests were used to compare SBS among the five subgroups (P < 0.05).

RESULTS

Feldspathic and IPS Empress e-Max ceramics had similar SBS values. The Ti:sapphire femtosecond laser (16.76 ± 1.37 MPa) produced the highest mean bond strength, followed by sandblasting (12.79 ± 1.42 MPa) and HF acid (11.28 ± 1.26 MPa). The Er:YAG (5.43 ± 1.21 MPa) and Nd:YAG laser (5.36 ± 1.04 MPa) groups were similar and had the lowest SBS values. More homogeneous and regular surfaces were observed in the ablation pattern with the Ti:sapphire laser than with the other treatments by SEM analysis.

CONCLUSIONS

Within the limitations of this in vitro study, Ti:sapphire laser- treated surfaces had the highest SBS values. Therefore, this technique may be useful for the pretreatment of ceramic surfaces as an alternative to 'conventional' techniques.

Effect of femtosecond laser treatment on the shear bond strength of a metal bracket to prepared porcelain surface

OBJECTIVE

The aim of this study was to investigate the effects of femtosecond laser treatment (Group FS) on the shear bond strength (SBS) of a metal bracket to prepared porcelain surface, and to compare it with other surface treatment techniques [50 μm Al2O3 sandblasting (Group SB), 9.6% hydrofluoric acid gel (Group HF), and neodymium-doped yttrium aluminium garnet (Nd:YAG laser) (Group NY)].

BACKGROUND DATA

Because of the increasing number of adult patients in current orthodontic practice, achieving sufficient bond strength of composite resin to porcelain restorations without bond failure during the treatment is a challenge for orthodontists.

METHODS

In total, 80 glazed feldspathic porcelain samples were prepared and randomly assigned to four groups of 20. Treated surfaces were treated with a silane agent. Brackets were bonded to porcelain samples. The specimens were stored in distilled water for 24 h and then thermocycled for 500 cycles between 5° and 55°C. The SBS of the brackets was tested with a universal testing machine at a crosshead speed of 1 mm/min, until bonding failure occurred. The data were analyzed statistically using analysis of variance (ANOVA) and Tamhane multiple comparisons tests. The results of ANOVA indicated that the SBS values varied according to the surface treatment method (p<0.001).

RESULTS

Results of the Tamhane post-hoc tests indicated that the bond strength in Group NY (5.11±1.53) was significantly lower than the other groups (p<0.05). There were no statistically significant differences among Groups SB (9.07±3.76), HF (9.09±3.51), and FS (11.58±4.16) (p=0.28).

CONCLUSIONS

The results of this study showed that FS treatment produced high SBS of the processes assessed; therefore, it appears to be an effective method for bonding orthodontic metal brackets to prepared porcelain surfaces.

Influence of surface treatments on bond strength of metal and ceramic brackets to a novel CAD/CAM hybrid ceramic material

This study evaluated the effect of four different surface treatments methods on the shear bond strength (SBS) of ceramic and metal brackets to Vita Enamic (VE) CAD/CAM hybrid ceramic. A total of 240 plates (10 mm × 10 mm × 3 mm) were cut from VE ceramic blocks and divided into two groups. In each group, four subgroups were prepared by hydrofluoric acid (HF); phosphoric acid (H3PO4); diamond ceramic grinding bur; and silica coating using CoJet system (CJ). Maxillary central incisor metal (Victory Series) and ceramic (Clarity) brackets were bonded with light-cure composite and then stored in artificial saliva for 1 week and thermocycled. The SBS test was performed, and the failure types were classified with adhesive remnant index scores. Surface morphology of the ceramic was characterized after treatment using a scanning electron microscope. Data were analyzed using two-way ANOVA, Tukey HSD test, and Weibull analysis. SBS was significantly affected by the type of bracket and by type of treatment (P < 0.001). Specimens treated with CJ presented with significantly higher SBS compared to other groups (P < 0.05). Improvements in SBS values (MPa) were found in the following order: CJ > HF > Bur > H3PO4. Ceramic bracket showed higher SBS compared to metal bracket. Adhesive failures between the ceramic and composite resin were the predominant mode of failure in all groups. Surface treatment of VE CAD/CAM hybrid ceramic with silica coating enhanced the adhesion with ceramic and metal brackets.

Rapid bonding and easy debonding of orthodontic appliances with 4-META/MMA-TBB resin using thermal heating

4-Methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butylborane (4-META/MMA-TBB) resin is widely used as a direct bonding adhesive for orthodontic appliances because of its strong bonding ability. However, its clinical disadvantages include long setting times and difficult debonding with subsequent residual adhesive left on the enamel surface. To resolve these problems, thermal heating was applied to orthodontic appliances. The setting time was dramatically reduced by thermal heating (160°C for 5 s), with the shear bond strength remaining the same as that stated in the manufacturer's instructions. Debonding of appliances following thermal heating (160°C for 20 s) could be easily performed, decreasing the amount of adhesive left on enamel. These conditions were not accompanied by an increase in the heat pain threshold of pulpal dentin. These results suggest that the use of thermal heating in the bonding/debonding of 4-META/MMA-TBB resin may resolve its clinical weaknesses, making its ease of use similar to light-cured resin.

Surface treatment of feldspathic porcelain: scanning electron microscopy analysis

PURPOSE

Topographic analysis of treated ceramics provides qualitative information regarding the surface texture affecting the micromechanical retention and locking of resin-ceramics. This study aims to compare the surface microstructure following different surface treatments of feldspathic porcelain.

MATERIALS AND METHODS

This in-vitro study was conducted on 72 porcelain discs randomly divided into 12 groups (n=6). In 9 groups, feldspathic surfaces were subjected to sandblasting at 2, 3 or 4 bar pressure for 5, 10 or 15 seconds with 50 µm alumina particles at a 5 mm distance. In group 10, 9.5% hydrofluoric acid (HF) gel was applied for 120 seconds. In group 11, specimens were sandblasted at 3 bar pressure for 10 seconds and then conditioned with HF. In group 12, specimens were first treated with HF and then sandblasted at 3 bar pressure for 10 seconds. All specimens were then evaluated under scanning electron microscopy (SEM) at different magnifications.

RESULTS

SEM images of HF treated specimens revealed deep porosities of variable sizes; whereas, the sandblasted surfaces were more homogenous and had sharper peaks. Increasing the pressure and duration of sandblasting increased the surface roughness. SEM images of the two combined techniques showed that in group 11 (sandblasted first), HF caused deeper porosities; whereas in group 12 (treated with HF first) sandblasting caused irregularities with less homogeneity.

CONCLUSION

All surface treatments increased the surface area and caused porous surfaces. In groups subjected to HF, the porosities were deeper than those in sandblasted only groups.

Comparison of shear bond strength of orthodontics brackets on composite resin restorations with different surface treatments

INTRODUCTION

Orthodontic patients frequently present composite resin restorations, however there are few studies that evaluate the best way for orthodontic bonding in this situation.

OBJECTIVE

The objective of this work was to evaluate the bond strength of orthodontic brackets in resin restorations with surface treatment.

METHODS

Fifty one bovine lower incisors were randomly divided into three groups. On the control group (CG) the brackets were bonded to dental enamel; on experimental groups, brackets were bonded to resin restoration with diamond drill treatment (EGT) and with no treatment (EGN). The teeth were placed in PVC tubes with self-etching acrylic resin. The shear test was performed in EMIC universal testing machine. The groups were submitted to ANOVA analysis of variance with Tukey post test to verify the statistical difference between groups (α = 0.05).

RESULTS

CG (6.62 MPa) and EGT (6.82 MPa) groups presented similar results, while EGN (5.07 MPa) obtained statistically lower results (p < 0.05).

CONCLUSIONS

Therefore, it is concluded that the best technique for bonding orthodontic brackets on composite resin restorations is the performance of surface detritions.

Orthodontic bonding to porcelain: a systematic review

OBJECTIVE

To use a systematic review to determine which materials and technique/protocol present the highest success rate in bonding brackets to porcelain surfaces.

MATERIALS AND METHODS

Different databases were searched without limitations up to July 2013. Additionally, the bibliographies of the finally selected articles were hand searched to identify any relevant publications that were not identified earlier. In vitro and in vivo articles were included.

RESULTS

No in vivo articles were found that fulfilled the inclusion criteria. A total of 45 in vitro articles met all inclusion criteria. They were published between 2000 to July 2013.

CONCLUSIONS

The best protocol described in this review is the etching of 9.6% hydrofluoric acid for 1 minute, rinsed for 30 seconds, and then air-dried. The etching of hydrofluoric acid should be followed by an application of silane. Considering the harmful effects of etching with hydrofluoric acid, another appropriate suggestion is mechanical roughening with sandblasting followed by an application of silane.

Effects of different surface treatments on shear bond strength in two different ceramic systems

The purpose of this study was to evaluate the influence of different surface treatments (sandblasting, acid etching, and laser irradiation) on the shear bond strength of lithium disilicate-based core (IPS Empress 2) and feldspathic ceramics (VITA VM 9). One hundred ceramic discs were divided into two groups of 50 discs each for two ceramic systems: IPS Empress 2 (group I) and VITA VM 9 (group II). Each of the two groups was further divided into five surface treatment groups (ten each) as follows: group SB, sandblasting with alumina particles (50 μm); group HF, 5 % hydrofluoric acid etching; group L, Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10 W; manually, noncontact R14 handpiece); group SB-L, sandblasting + Er:YAG laser; and group HF-L, 5 % hydrofluoric acid + Er:YAG laser. Luting cement (Panavia 2.0) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, a shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference tests (α = 0.05). The two-way ANOVA indicated that the shear bond strength was significantly affected by the surface treatment methods (p < 0.05), but there was no significant interaction between the ceramic systems. Group SB-L had the highest mean values for each ceramic system. Sandblasting, followed by Er:YAG laser irradiation, enhanced the bond strength, indicating its potential use as an alternative method. The atomic force microscopic evaluation revealed that group SB had the most distinct sharp peaks among the groups.

Comparison of shear bond strength of metal brackets bonded to porcelain surface using different surface conditioning methods: an in vitro study

AIM

To evaluate and compare the shear bond strength of metal brackets bonded to ceramic surfaces using different conditioning methods and to assess the site of bond failure after debonding.

MATERIALS AND METHODS

A total of 70 ceramic surfaces were produced with uniform shape, size and composition. The samples were divided into 7 groups (each of 10 samples). Group 1 was the control group (untreated surface); in group 2 the surface were roughened with a diamond bur; in group 3 the surface were etched with hydrofluoric acid; in group 4 the surfaces were sandblasted; in group 5 the surfaces roughened with bur and silane applied; in group 6 the surfaces were etched with hydrofluoric acid and silane applied and in group 7 the surfaces were sandblasted and silane applied. To all the above groups, metal orthodontic brackets were bonded with light cure adhesive. The brackets were later stored in artificial saliva and incubated at 37°C (24 hours). The samples were then subjected to shear bond strength test using an Instron universal testing machine. The debonded porcelain surfaces were then studied under stereomicroscope to assess site of bond failure.

RESULTS

Sandblasting the ceramic surface and silane application showed the highest bond strength. Stereomicroscope examination after debonding showed that the bond failure is at bracket-adhesive interface in four groups namely hydrofluoric acid, sandblasting, hydrofluoric acid with silane and sandblasting with silane.

CONCLUSION

Sandblasting with silane combination produced the highest shear bond strength, so it is a clinically suitable method for bonding orthodontic metal brackets onto ceramic surface.

CLINICAL RELEVANCE

Bonding orthodontic brackets to ceramic crowns of patients has been a tough task. In this study, different conditioning methods were used to treat the ceramic surfaces before bonding. The results showed that sandblasting the ceramic surface prior to application of silane produced the highest shear bond strength which is clinically suitable to reduce bond failures.