Effect of surface treatment with sandblasting and Er,Cr:YSGG laser on bonding of stainless steel orthodontic brackets to silver amalgam

Effect of different surface treatment with panaviaV5 on shear bond strength of metal brackets to silver amalgam

BACKGROUND

This study was conducted to compare the shear bond strength (SBS) of orthodontic brackets to amalgam surfaces by two surface treatment methods, two different adhesives, and one intermediate resin and also to evaluate surface roughness after two preparation methods as well as bond failure mode.

MATERIALS AND METHODS

In this in-vitro study forty-eight amalgam samples were randomly allocated to four groups. In Groups 1-3, specimens were sandblasted with 50 μm aluminum oxide, followed by application of Alloy primer in Groups 1 and 2. In Group 3 Alloy primer had not used. In Group 4, samples were prepared by silica coating using a silane coupling agent. Surface roughness analysis was performed in 10 additional samples after two surface treatments. The brackets in Group 1 were bonded with Transbond XT and those in other groups were bonded with Panavia V5. All specimens were examined for SBS following 5000 times thermocycling at 5°C-50°C. Modified adhesive remnant index was utilized for the bond failure mode. Data analysis was done by one-way analysis of variance, post hoc Tukey, Kruskal-Walli and Mann-Whitney U tests. Statistical significance was set at P < 0.05.

RESULTS

The findings indicated the mean SBS were low (ranged from 0.19 to 4.66 MPa) and significantly lower in Group 3 than in Group 4 (P = 0.009). Bond failure occurred in adhesive/amalgam interface in nearly all samples. Silica coating produced significantly lower roughness than sandblast (P = 0.009).

CONCLUSION

Silica coating had a significant higher bond strength than sandblast without application of Alloy primer. However compared to sandblast with Alloy primer, silica coating did not significantly improve the bond strength. Chemical bond between PanaviaV5 and sandblasted amalgam was not considerable.

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.

Use of Laser Systems in Orthodontics

Laser systems have been used in the practice of dentistry for >35 years. Laser systems have so many advantages, such as increase patient cooperation, reduce the duration of treatment time, and help the orthodontists to enhance the design of a patient's smile to improve treatment efficacy, and the success of orthodontic treatments can also be improved by diminishing the orthodontic pain and the discomfort of the patients. Laser systems also have some disadvantages, such as cost, large space requirements for some types, and high-risk potential for physician and patient if not used at the appropriate wavelength and power density, that is why before incorporating lasers into clinical practice, the physician must fully understand the basic science, safety protocol, and risks associated with them. Lasers have many applications in orthodontics, including accelerating tooth movement, bonding and debonding processes, pain reduction, bone regeneration, etching procedures, increase mini-implant stability, soft tissue procedures (gingivectomy, frenectomy, operculectomy, papilla flattening, uncovering temporary anchorage devices, ablation of aphthous ulcerations, and exposure of impacted teeth), fiberotomy, scanning systems, and welding procedures. In reviewing the literature on the use of laser in orthodontics, many studies have been conducted. The purpose of the present study was to give information about the use of laser in the field of orthodontics, the effects of laser during the postoperative period, and its advantages and disadvantages and to provide general information about the requirements to be considered during the use of laser.

Surface modification for bonding between amalgam and orthodontic brackets

OBJECTIVE

Testing of methods to enhance the shear bond strength (SBS) between orthodontic metal brackets and amalgam by sandblasting and different primers.

MATERIALS AND METHODS

Three hundred samples of amalgam restorations (KerrAlloy^®) were prepared in self-cured acrylic blocks, polished, and divided into two groups: nonsandblasted and sandblasted. Each group was divided into five subgroups with different primers used in surface treatment methods, with a control group of bonded brackets on human mandibular incisors. Following the surface treatments, mandibular incisor brackets (Unitek^®) were bonded on the amalgam with adhesive resin (Transbond XT^®). The SBS of the samples was tested. The adhesive remnant index (ARI) and failure modes were then determined under a stereo-microscope. Two-way analysis of variance, Chi-square, and Kruskal-Wallis tests were performed to calculate the correlations between and among the SBS and ARI values, the failure modes, and surface roughness results.

RESULTS

There were statistically significant differences of SBS among the different adhesive primers and sandblasting methods (P < 0.05). The sandblasted amalgam with Assure Plus^® showed the highest SBS (P < 0.001). Samples mainly showed an ARI score = 1 and mix-mode failure. There was a statistically significant difference of surface roughness between nonsandblasted amalgam and sandblasted amalgam (P < 0.05), but no significant differences among priming agents (P > 0.05).

CONCLUSIONS

Using adhesive primers with sandblasting together effectively enhances the SBS between orthodontic metal brackets and amalgam. The two primers with the ingredient methacryloxydecyl dihydrogen phosphate (MDP) monomer, Alloy Primer^® and Assure Plus^®, were the most effective. Including sandblasting in the treatment is essential to achieve the bonding strength required.

Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

INTRODUCTION

The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM).

METHODS

Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM.

RESULTS

The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets.

An in vitro evaluation of the effect of sandblasting and laser surface treatment on the shear bond strength of a composite resin to the facial surface of primary anterior stainless steel crowns

OBJECTIVES

The present study was conducted to evaluate the optimal method of enhancing the bond strength of a composite resin to the facial surface of the primary anterior stainless steel crowns using various surface treatments namely Nd: YAG laser surface treatment, sandblasting , alloy primer application and no surface treatment.

STUDY DESIGN

The study sample consisted of 60 primary anterior stainless steel crowns (UnitekTM size R 4), with 15 samples randomly divided into the 4 study groups, embedded in acrylic blocks. The facial surface of these surface treated crowns was utilized as the bonding surface to which 2.5mm diameter composite resin cylinders were bonded for the evaluation of the shear bond strength. Shear bond strength measurements were made using a universal testing machine utilizing a shearing blade (jig).The mode of failure at composite-metal interface was determined using a Stereomicroscope at 10 X magnification.

RESULTS

The mean bond strength values obtained for surface treatment of Nd: YAG laser surface treated, Sandblasting ,Alloy Primer and No surface treatments were 17.01±.92 , 13.18 ± .73, 7.46 ± .70 and 7.33 ± .77 MPa respectively. The obtained bond strength values were subjected to a one way ANOVA and a Scheffe's post-hoc comparison test. The results of the present study indicated that Laser surface treatment of the facial surface of the crowns enhanced the bond strength of the composite resin significantly compared to the other groups.

CONCLUSIONS

Nd: YAG laser surface treatment produced an excellent surface roughness and obtained the highest shear bond strength values suggestive for recommendation as an optimal surface treatment to be used to enhance the resin-metal bond at the interface of the composite resin and the facial surface of primary anterior stainless steel crowns for the purpose of chairside veneering. Key words:Nd: YAG laser treatment, Sandblasting, Primary anterior stainless steel crown, Chairside veneering, Enhancing Resin-Metal Bond, Early childhood caries, Shear bond strength (SBS).

Effect of different temporary crown materials and surface roughening methods on the shear bond strengths of orthodontic brackets

OBJECTIVE

The aim of this study was to evaluate the effect of different temporary crown materials (TCMs) and surface roughening methods on the shear bond strength (SBS) of orthodontic brackets.

BACKGROUND DATA

TCMs are widely used during orthodontic treatment in teeth in need of prosthetic treatment, to prevent damage to the final restoration. However, there is no consensus considering the best method for roughening of the surface of TCMs.

METHODS

Five different TCMs [Dentalon Plus-(D), Basworth Trim II-(B), Voco Structure Premium-(V), 3M ESPE Protempt 4-(P), and Revotek LC-(R)] were used in this study. Different surface roughening methods (37% phosphoric acid, sandblasting, and Er:YAG laser) were employed in three subgroups (n=20). The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group.

RESULTS

The highest mean SBS value was observed in group V, followed by groups D and P, regardless of the surface treatment. The lowest SBS values were observed in group B. The laser-irradiated groups had higher SBS values than the sandblasted and acid-etched groups. Furthermore, a significant difference in SBS values was observed between the laser-irradiated group V and all other groups (p<0.005).

CONCLUSIONS

The effects of the chemical nature of TCMs on the SBS values appeared to be clinically negligible, whereas the type of surface treatments had a significant influence on bond strengths. Er:YAG laser irradiation caused a significant increase in bond strength between the TCMs and orthodontic brackets.

The effect of surface treatment with Er: YAG laser on shear bond strength of orthodontic brackets to fiber-reinforced composite

OBJECTIVES

This study aimed to investigate the effect of surface treatment with Er:YAG laser on shear bond strength (SBS) of orthodontic brackets to fiber-reinforced composite (FRC).

STUDY DESIGN

Ninety human premolars were randomly divided into six groups of 15. FRC bars were bonded to the teeth with a flowable composite (FC) and then underwent following treatments. In group 1 no further treatment was performed. In group 2 the FRC surfaces were covered by FC. An Er:YAG laser was employed to treat FRCs in groups 3 ( 200 mJ/10 Hz) and 4 (300 mJ/15 Hz). The FRC strips in groups 5 and 6 were first covered by FC and then irradiated with Er:YAG laser at 200 mJ/10 Hz (group 5) or 300 mJ/15 Hz (group 6). Stainless steel brackets were bonded to FRCs using a light-cure adhesive system. After 24 hours, the samples were tested for SBS and the adhesive remnant index (ARI) scores were determined.

RESULTS

There was a significant difference in SBS among the study groups (P <0.001). Pairwise comparisons indicated that SBS was significantly lower in group 1 compared to all other groups (p<0.05) except group 2. Bond strength in group 6 was significantly greater than all the study groups (p<0.05) except group 5. No significant difference was found in ARI scores among the groups.

CONCLUSIONS

Covering the FRC surface by a layer of flowable composite and then application of Er:YAG laser at 300 mJ/15 Hz could be recommended to increase bond strength of orthodontic attachments to FRC. Key words:Fiber-reinforced composite, orthodontics, Sshear bond strength, laser, Er:YAG, surface treatment, bracket, FRC.

A Comparison of Shear Bond Strengths of Metal and Ceramic Brackets using Conventional Acid Etching Technique and Er:YAG Laser Etching

Background and aims. The aim of this study was to compare shear bond strength (SBS) of metal and ceramic brackets bonded to enamel using acid versus Er:YAG laser etching.

Materials and methods. Eighty premolars were divided into 4 groups: AM (acid etching/ metal brackets), AC (acid etching/ ceramic brackets), LM (laser etching/ metal brackets) and LC (laser etching/ ceramic brackets). Enamel condition-ing was done using acid in AC and AM and Er:YAG laser in LC and LM. Brackets were debonded with a Dartec machine and the SBSs were determined. Adhesive remnant index was evaluated under a stereomicroscope. Two additional teeth were conditioned with acid and laser for scanning electron microscopy examination. Comparisons of SBS value were done by ANOVA test.

Results. statistical analyses showed that SBSs of acid groups were significantly higher than that of laser groups, but dif-ferences between SBS values of AC/ AM and LC/LM were not significant. SEM examination revealed different etching pattern.

Conclusion. Low power Er:YAG laser etching offers clinically acceptable SBS which besides its other superiorities to acid etching can be an appropriate alternative for bonding of ceramic brackets.