Influence of air-powder polishing on bond strength and surface-free energy of universal adhesive systems

Influence of airborne particle abrasion on dentin bonding effectiveness of a 2-step universal adhesive

OBJECTIVE

To determine the effect of airborne particle abrasion (APA) on micro-tensile bond strength (µTBS) to dentin using different air-abrasion/polishing powders.

METHODS

The bonding effectiveness of G2 Bond Universal (G2B), used in etch-and-rinse (E&R) and self-etch mode (SE), was tested on bur-cut dentin and dentin air abraded/polished using six different powders (aluminum oxide 29 µm (AO29) and 53 µm (AO53), aluminum trihydroxide (AT), sodium bicarbonate (SB), sodium bicarbonate soft (SBsoft) and bioactive glass (BG); Velopex). Adhesive-composite resin specimens were immersed in distilled water at 37 °C for one week and cut into microspecimens. Half of the specimens were subjected to 50,000 thermocycles (aged). Immediate and aged μTBS to dentin were measured. Statistical analysis was performed using linear mixed-effects (LME) modeling (p < 0.05).

RESULTS

Comparing the aged bond strengths to air-abraded/polished dentin with bur-cut dentin, pretreatment with SB and SBsoft in combination with G2B used in E&R mode, and BG air polishing in combination with both application modes (E&R, SE), resulted in a significantly higher bond strength. Dentin bond strength was only significantly lower when air abraded with AO29 and using G2B in SE mode. Aging did not significantly influence bond strength for both application modes (E&R, SE), except for AO29 and AT-treated dentin, where bond strengths decrea sed significantly using G2B in SE mode. In general, G2B reached significantly higher bond strengths on air-abraded/polished dentin in E&R mode than in SE mode.

CONCLUSION

Air-abrasion/polishing did not impair dentin bond strength using G2B, except when dentin was air abraded with AO29 and using G2B in SE mode. Air polishing positively influenced the bond strength to dentin in specific groups.

CLINICAL SIGNIFICANCE

APA is safe concerning bonding to dentin. The E&R application mode is preferred using G2B as adhesive on air-abraded/polished dentin. Air polishing with BG positively influenced dentin bond strength for both application methods.

Treatment of saliva contamination of resin core foundation before adhesive luting

This study aimed to evaluate the influence of surface pretreatment on the shear bond strength of resin luting cement to saliva-contaminated resin core foundation. The surface free energy (γS) of the adherent surfaces was examined. The two-way analysis of variance revealed that the surface pretreatment and storage conditions had a significant effect on the strength of the bond to resin core foundation. The γS values of the saliva-contaminated group were significantly lower than those of the other groups, and they tended to improve after surface pretreatment. The tendency of improvement in γS values differed depending on the type of pretreatment agents. Surface treatment with solutions containing functional monomers is effective in removing saliva contaminants from the resin core foundation surfaces and in creating an effective bonding surface for the resin luting cement.

An In Vitro Evaluation of the Effects of Air-Polishing Powders on Sound and Demineralised Enamel

AIM

To evaluate the effects of two air-polishing powders, during orthodontic treatment, on the surface roughness of sound and demineralised enamel.

MATERIALS AND METHODS

Forty-two caries-free human molars were collected, and the enamel surfaces were flattened and polished. Teeth were assigned to two groups (n = 21 each), a sound- and a demineralised-enamel group (subjected to pH-cycling over 2 weeks to create artificially induced white spot-like lesions). Within each group, teeth were further assigned to three groups (n = 7 each), air polished with either sodium bicarbonate, erythritol, or a negative control (water). Each sample was treated for 5 and 150 s. The average surface roughness (Ra) for each sample was measured using white-light-sensor profilometry.

RESULTS

On sound enamel, the Ra was roughly 0.17 ± 0.07 μm. After 150 s of air polishing, the Ra increased with erythritol (by 0.28 μm), and even more so with bicarbonate treatment (by 0.68 μm) (p < 0.01). On demineralised enamel, the Ra was roughly 0.79 ± 0.56 μm. The Ra increased after 5 s of air-polishing treatment similarly with erythritol and bicarbonate powders (by 1.03 μm and 1.04 μm, respectively) (p = 0.025), and even more after 150 s (by 2.48 μm and 2.49 μm, respectively) (p < 0.001).

CONCLUSIONS

On white spot lesions, one should be aware that enamel surface roughness will increase with both erythritol and bicarbonate air-polishing powders, especially with longer exposure times.

The Effect of Ultrasonic Scaling and Air-Powder Polishing on the Roughness of the Enamel, Three Different Nanocomposites, and Composite/Enamel and Composite/Cementum Interfaces

We aimed to assess the effects of ultrasonic scaling and air-powder polishing on the roughness of enamel, three nanocomposites (Premise, Herculite Ultra, Harmonize), and composite/enamel and composite/cementum interfaces. Class V cavities were restored in 99 extracted third molars with one of the three nanocomposites and treated with ultrasonic scaler or air-powder polishing device (calcium carbonate or sodium bicarbonate powders). The roughness (Ra) of the investigated surfaces was measured with contact profilometer before and after treatment. The data were analyzed using repeated measures ANOVA. Specimens' Ra values before instrumentation were near the clinically acceptable 0.2 μm threshold. All techniques increased the roughness of the tested surfaces; however, the enamel was slightly affected. The mean Ra values after prophylaxis for composite, composite/cementum and composite/enamel surfaces were 0.32-0.55, 1.33-1.73, and 1.25-1.36, respectively. The extent of composite surface damage was material dependent. Premise surface was not altered by ultrasonic scaling significantly. Air-powder polishing with both powders produced a greater increase in surface roughness of composite resin and restorations margins than ultrasonic scaling. The Ra values after both types of air polishing for Herculite Ultra and Harmonize were approximately 1.5 and 2 times higher, respectively, than those after ultrasonic scaling (p < 0.05).

Effect of a temporary sealing material on the bond strength of CAD/CAM inlay restorations with resin-coating technique

This study aimed to assess the effects of a temporary sealing material and cleaning method of resin-coated dentin on the bond strength of computer-aided design/computer-aided manufacturing (CAD/CAM) inlay restorations. Resin-coated dentin surfaces were unsealed or temporarily sealed for 1 h or 1 week. For the temporarily sealed group, a hydraulic temporary sealing material was removed and further divided into four groups: without cleaning, cleaned with a rotational brush, a universal cleaner or an air-polishing device. Some specimens were investigated with energy dispersive X-ray spectroscopy and the others were used for microtensile bond strength (MTBS) test. A sealing material could not be removed with a rotational brush, which resulted in pretest failures in all specimens after 1 h and which resulted in low MTBS after 1 week. An air-polishing device can clean resin-coated dentin temporarily sealed with a hydraulic temporary sealing material and resulted in the similar MTBS as in the unsealed group.

Microtensile Bond Strength of Etch-and-Rinse Adhesives in Different Hydroabrasion Conditionings

The aim of the present study was to in vitro evaluate the effect of dentin conditioning with hydroabrasion on the microtensile bond strengths of three adhesive systems, compared to the standard etch-and-rinse technique. Sixty extracted human third molars were collected, and their midcoronal occlusal dentin was used for the microtensile bond strength test. Teeth were randomly assigned to three groups according to the adhesive system used: ExciTE F DSC, ENA Bond, and Scotchbond Universal. Specimens from each group were further divided into four subgroups: control specimens were treated with standard adhesive procedures; hydroabraded (HA) specimens were subjected to preventive hydroabrasion with three different intensity levels. After bonding procedures, composite crowns were incrementally built up. After thermocycling, specimens were subsequently sectioned into 1 × 1 mm sticks, and microtensile bond strengths were measured. Data were statistically analyzed. Failure mode analysis was performed. There were no significant differences in terms of bond strength between standard adhesion protocols and adhesion with HA preconditionings. On the other hand, the type of adhesive used had a significant effect on the tensile bond strength. Subgroups treated with hydroabrasion at higher intensity showed a slightly increased frequency of cohesive fractures. In conclusion, hydroabrasion can be used for dentin cavity preparation or finishing, since it does not seem to affect the bonding effectiveness.

Bond Strength of Universal Adhesives to Dentin: A Systematic Review and Meta-Analysis

Currently, the availability of a wide variety of universal adhesives makes it difficult for clinicians to choose the correct system for specific bonding situations to dentin substrate. This study aimed to determine whether there are any alternative techniques or additional strategies available to enhance the bond strength of universal adhesives to dentin through a systematic review and meta-analysis. Two reviewers executed a literature search up to September 2020 in four electronic databases: PubMed, ISI Web of Science, Scopus, and EMBASE. Only in vitro studies that reported the dentin bond strength of universal adhesives using additional strategies were included. An analysis was carried out using Review Manager Software version 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). The methodological quality of each in vitro study was assessed according to the parameters of a previous systematic. A total of 5671 potentially relevant studies were identified. After title and abstract examination, 74 studies remained in systematic review. From these, a total of 61 studies were included in the meta-analysis. The bond strength of universal adhesives to dentin was improved by the use of one of the following techniques: Previous application of matrix metalloproteinases (MMP) inhibitors (p < 0.001), prolonged application time (p = 0.007), scrubbing technique (p < 0.001), selective dentin etching (p < 0.001), non-atmospheric plasma (p = 0.01), ethanol-wet bonding (p < 0.01), prolonged blowing time (p = 0.02), multiple layer application (p = 0.005), prolonged curing time (p = 0.006), and hydrophobic layer coating (p < 0.001). On the other hand, the use of a shortened application time (p = 0.006), and dentin desensitizers (p = 0.01) impaired the bond strength of universal adhesives to dentin. Most of the analyses performed showed a high heterogenicity. The in vitro evidence suggests that the application of universal adhesives using some alternative techniques or additional strategies may be beneficial for improving their bonding performance to dentin. This research received no external funding. Considering that this systematic review was carried out only with in vitro studies, registration was not performed.

The effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using the resin-coating technique

This study evaluated the effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using resin-coating technique. Scotchbond Universal Adhesive and Filtek Supreme Ultra Flowable were applied to bovine dentin. Forty-five specimens were divided into the following three groups according to the temporary sealing materials: Cav-: CAVITON EX, Vas-: COCOA BUTTER and FIT SEAL, and Sep-: Washable SEP and FIT SEAL. Each material was placed on resin-coated dentin. After 1-week water storage, one of the following three cleaning protocols was performed: -WA: washed with water, -BR: brushed with PRESSAGE, and -AF: cleaned with AIR-FLOW. Microtensile bond strength test and EDS analysis were conducted. Irrespective of the cleaning protocol used, Washable SEP demonstrated less residual debris on resin-coated dentin, resulting in high bond strength. Regardless of the temporary sealing material applied, AIR-FLOW demonstrated less residual debris, resulting in high bond strength.

Effects of alumina airborne-particle abrasion on the surface properties of CAD/CAM composites and bond strength to resin cement

The purpose of this study is to clarify physical and chemical changes in surfaces of CAD/CAM composites caused by alumina airborne-particle abrasion and its effect on adhesive bonding. Our study involved three dispersed filler (DF)-based and a polymer-infiltrated ceramic network (PICN)-based CAD/CAM composites. Changes in the surface morphologies of the composites were examined, and surface free energy (SFE) analysis was performed based on Owens-Wendt theory. The influence of the abrasion on the bond strengths of CAD/CAM composites to the resin cement was characterized by shear bond strength (SBS) test. The abrasion increased the roughness of the composites. The SFE analysis showed that the abrasion significantly increased the dispersive component but decreased the polar component of the SFE associated with the DF-based composites, while no change occurred for those of the PICN-based composite. The abrasion slightly improved the SBSs for the DF-based composites but not that of the PICN-based composite.

Influence of surface treatment on bonding of resin luting cement to CAD/CAM composite blocks

The aim of this study was to determine the influence of different surface treatments of CAD/CAM composite blocks on bonding effectiveness of resin cements, based on the shear bond strength test and the surface science examination. Specimens were fabricated from two types of CAD/CAM composite blocks (Cerasmart and VITA Enamic), and the specimen surfaces were alumina sandblasted. Specimen surfaces were treated with i) silane, ii) primer, and iii) silane+primer, then two types of cements (Block HC Cem and Super Bond) were bonded. After 24 h storage, bond strengths were measured. Surface free energy measurements were performed of the treated CAD/CAM composite blocks surfaces. The groups ii) and iii) showed significantly higher bond strengths than the group i), apart from VITA Enamic with Block HC Cem. Although the total surface free energy showed different trends in different surface treatments, a similar trend was found in both CAD/CAM composite blocks.

The Effects of Aluminablasting on Bond Durability Between Universal Adhesives and Tooth Substrate

The aim of this study was to determine the effect of aluminablasting on the bond durability of universal adhesives and adherent surface characteristics. Adhese Universal (Ivoclar Vivadent), All-Bond Universal (Bisco), Bondmer Lightless (Tokuyama Dental), G-Premio Bond (GC), and Scotchbond Universal (3M ESPE) were used in self-etch mode. The prepared bovine enamel and dentin specimens were divided into two groups based on whether they received an aluminablasting prior to application of the universal adhesives. The resin composite bonded specimens were stored in distilled water at 37°C for 24 hours, following which the shear bond strength (SBS) of half of the specimens was measured (24-hour group). The other half was subjected to 30,000 thermal cycles between 5 and 55°C before SBS measurement (TC group). Surface roughness (Ra) and surface free energy (SFE) of the adherent surfaces were also measured, and scanning electron microscopy observation and scanning electron microscopy/energy-dispersive X-ray analysis were carried out. Most of the adhesives did not show any significant differences in enamel SBS values between the two pretreatment groups, regardless of the storage condition. However, the dentin SBS values were significantly lower in specimens that underwent aluminablasting compared with those that did not, irrespective of their storage conditions. Significantly higher Ra and SFE values were observed in the enamel and dentin of specimens that underwent aluminablasting. Although aluminablasting increased the Ra and SFE values of enamel and dentin, its effect on the SBS value was dependent on the tooth substrate. In addition to C, O, Na, Mg, P, and Ca, the element Al was detected in the enamel and dentin of samples that had undergone aluminablasting. These results suggest that although aluminablasting of the tooth surface is thought to be effective for modification of the adherent surface, it may not enhance enamel bond performance and may also adversely affect the dentin bond effectiveness of the universal adhesives.