Validity of bond strength tests: A critical review: Part I

Minimally Invasive Esthetic Reinforcement of a Fractured Anterior Tooth Using Dentapreg PINPost: A Case Report

The reason to use post is to retain the core that holds the definitive prosthesis. The maxillary central incisor always poses a challenge during reconstruction using the post and core system. Dentapreg PINPost, a pre-cured flexible post made of fiber-reinforced composite (FRC), has many advantages over metallic posts and fiber posts. The purpose of this case report is to present an innovative technique to place both FRC posts and FRC sheets as a single assembly into the canal which gives a monoblock effect. This technique is feasible and may eradicate some of the problems associated with the failure of the post and core.

Optimizing Dental Bond Strength: Insights from Comprehensive Literature Review and Future Implications for Clinical Practice

This review examines the modifying factors affecting bond strength in various bonding scenarios, particularly their relevance to the longevity of dental restorations. Understanding these factors is crucial for improving clinical outcomes in dentistry. Data were gathered from the PubMed database, ResearchGate, and Google Scholar resources, covering studies from 1992 to 2022. The findings suggest that for dentin-resin bonds, minimizing smear layers and utilizing MMP inhibitors to prevent hybrid layer degradation are essential. In the case of resin-resin bonds, reversing blood contamination is possible, but preventing saliva contamination is more challenging, underscoring its critical importance during clinical procedures. Additionally, while pretreatment on ceramics has minimal impact on bond strength, the influence of specific colorings should be carefully considered in treatment planning. This comprehensive review highlights that although established practices recognize significant bond strength factors, ongoing research provides valuable insights to enhance the clinical experience for patients. Once confirmed through rigorous experimentation, these emerging findings should be swiftly integrated into dental practice to improve patient outcomes.

Bond Strength of Reline Materials to 3D-Printed Provisional Crown Resins

(1) Purpose: The aim of the present study was to compare the bond strength between two 3D-printed resins designed for long-term provisional crowns and three different reline materials. (2) Materials and Methods: Rectangular specimens were prepared from two 3D-printed resins (Envision Tech and NextDent C&B) and a conventional self-cure PMMA. Transparent tubes filled with three different reline materials including composite resin, Bis-acryl, and PMMA were bonded to the 3D-printed specimens (n = 11 per group, total of 6 study groups). Tubes filled with PMMA were bonded to the prepared PMMA specimens which served as the control group (n = 11, control group). The specimens were subjected to a shear bond strength (SBS) test, and mode of failure was recorded using light microscopy. Statistical analysis was performed using a one-way ANOVA and post hoc Tukey's tests (alpha = 0.05). (3) Results: The highest SBS value was achieved to both 3D-printed materials with the PMMA reline material. The bond to both 3D-printed materials was lower with Bis-acrylic or composite resin relines in comparison to that with PMMA (p-value < 0.05). No significant difference was found between the control PMMA group and either 3D-printed material when relined with PMMA (p-value > 0.05). (4) Conclusion: The tested 3D-printed resins achieved a clinically acceptable bond strength when relined with PMMA.

Machine Learning Analysis of Microtensile Bond Strength of Dental Adhesives

Dental adhesives provide retention to composite fillings in dental restorations. Microtensile bond strength (µTBS) test is the most used laboratory test to evaluate bonding performance of dental adhesives. The traditional approach for developing dental adhesives involves repetitive laboratory measurements, which consumes enormous time and resources. Machine learning (ML) is a promising tool for accelerating this process. This study aimed to develop ML models to predict the µTBS of dental adhesives using their chemical features and to identify important contributing factors for µTBS. Specifically, the chemical composition and µTBS information of 81 dental adhesives were collected from the manufacturers and the literature. The average µTBS value of each adhesive was labeled as either 0 (if <36 MPa) or 1 (if ≥36 MPa) to denote the low and high µTBS classes. The initial 9-feature data set comprised pH, HEMA, BisGMA, UDMA, MDP, PENTA, filler, fluoride, and organic solvent (OS) as input features. Nine ML algorithms, including logistic regression, k-nearest neighbor, support vector machine, decision trees and tree-based ensembles, and multilayer perceptron, were implemented for model development. Feature importance analysis identified MDP, pH, OS, and HEMA as the top 4 contributing features, which were used to construct a 4-feature data set. Grid search with stratified 10-fold cross-validation (CV) was employed for hyperparameter tunning and model performance evaluation using 2 metrics, the area under the receiver operating characteristic curve (AUC) and accuracy. The 4-feature data set generated slightly better performance than the 9-feature data set, with the highest AUC score of 0.90 and accuracy of 0.81 based on stratified CV. In conclusion, ML is an effective tool for predicting dental adhesives with low and high µTBS values and for identifying important chemical features contributing to the µTBS. The ML-based data-driven approach has great potential to accelerate the discovery of new dental adhesives and other dental materials.

Phytic Acid: A Novel Dentine Conditioning Agent for Glass Ionomer Cement Restorations: An In Vitro Scanning Electron Microscopic Study

Background

Various dentin conditioners have been recommended to enhance the bond strength of glass ionomer cement (GIC) to dentin. The purpose of the in vitro study was to determine the efficacy of three dentin conditioners on the microshear bond strength of GIC and the failure patterns of the restoration, as well as the efficacy of removing the smear layer using a scanning electron microscope (SEM).

Materials and Methods

Eighty healthy mandibular premolars were cleaned, isolated, and divided into four groups (n = 20). Flat coronal dentinal surfaces were accomplished by removing the occlusal surface of the crowns. Each group received the following treatment: group 1 with 10% polyacrylic acid; group 2 with 10% ethylenediaminetetraacetic acid (EDTA); group 3 with 1% phytic acid; and group 4 with no conditioning (control). High-strength Fuji IX GIC was applied to the dentin, and samples were thermocycled and de-bonded with a crosshead speed of 0.5 mm/min employing a shear force. A stereomicroscope and a SEM were used to examine the dentin surface at magnifications of 2000× and 5000×. One-way analysis of variance (ANOVA), Tukey's post hoc test, and Chi-squared test were used to assess data on microshear bond strength, smear layer removal, and failure modes.

Results

The bond strength of group 4 was statistically highly significant (P ≤ 0.001) compared to the other groups. However, the differences between groups 2 and 3 were insignificant. Mixed pattern of failure was the least in group 3 (IP6). In group 3, the SEM photomicrograph revealed open dentinal tubules with complete removal of the smear layer.

Conclusion

The results of the present study affirm that phytic acid enhances the bond strength of GIC restorations and removal of smear layer to a level comparable to EDTA as a dentin conditioner.

Comparison of Shear Bond Strength and Microleakage between Activa™ Bioactive Restorative™ and Bulk-Fill Composites-An In Vitro Study

Bioactive materials have emerged as a promising alternative to conventional restorative materials as part of more conservative dentistry. The aim of this study was to evaluate and compare the shear bond strength (SBS) and microleakage of a new bioactive restorative material, two bulk-fill restorative composites, and a conventional composite at 24 h, 4 weeks, and 8 weeks. Three hundred and sixty molars and premolars were divided into four groups: ACTIVA™ BioACTIVE Restorative™, Filtek™ Bulk-Fill Restorative Composite, Tetric^® N-Ceram Bulk-Fill Composite, and G-aenial^® Composite. The normality of the data was determined with the Kolmogorov-Smirnov test, then the two-way ANOVA and Fisher's test were used for analyzing SBS data, and the Kruskal-Wallis and DSCF tests were conducted to analyze the microleakage. In the SBS test, there were no statistically significant differences between materials (p = 0.587), and the relation between material and time (p = 0.467), time points showed statistically significant differences (p = 0.016). As for the microleakage, statistically significant differences were found for all three time periods (p < 0.05), showing the conventional composite to have the lowest microleakage, followed by the bioactive material, and lastly the two bulk-fill composites. In conclusion, the new bioactive material has similar evaluated properties to bulk-fill composites (bond strength) and conventional composites (bond strength and microleakage) and can be used as an alternative restorative material.

Shear Bond Strength and Fluoride Release of a Universal Adhesive: An In-Vitro Study on Primary Teeth

This investigation aimed to assess the shear bond strength and fluoride-releasing capabilities of Clearfil Universal Bond Quick (Kuraray Noritake Dental Inc., Tokyo, Japan). Forty-four extracted primary molars were divided into two groups, and the enamel substrate was prepared for evaluating shear bond strength. Scotchbond (3M ESPE) and Clearfil UBQ were used to bond composite-to-enamel substrates in each group (n = 22). Shear bond strength was measured using a universal testing device and compared. Sixteen discs (6 mm diameter and 3 mm thickness) were fabricated from each Clearfil UBQ, Fuji IX, and Fuji II LC. Over the course of 30 days, each materials' fluoride release was examined and compared using ion analysis. Results revealed that Clearfil UBQ had statistically similar shear bond strength to Scotchbond. Between the three materials, Clearfil UBQ had the lowest fluoride release at baseline (0.11 ± 0.25) and the lowest cumulative fluoride release (0.12-0.27 ppm) over 30 days. Fuji IX had the highest fluoride release at baseline (19.38 ± 2.50) and cumulatively (40.87 ± 4.03 ppm), followed by Fuji II LC. We conclude that Clearfil UBQ and Scotchbond showed comparable bond strengths to the enamel. Fluoride release was seen in Clearfil UBQ in the initial two days of the 30-day period. The amount of fluoride release was significantly less than with glass ionomer cements.

The Shear Bond Strength between Milled Denture Base Materials and Artificial Teeth: A Systematic Review

The data about bond strength between digitally produced denture base resins and artificial teeth are scarce. Several studies investigated shear bond strength values of milled denture base resins and different types of artificial teeth. The purpose of the present study was to compare and evaluate the available evidence through a systematic review. A bibliographic search was conducted in PubMed, Scopus, and Web of Science to assess adequate studies published up to 1 June 2022. This review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The appropriate studies that determined the shear bond strength values between milled denture base resins and artificial teeth were selected. The initial search identified 103 studies, which were included in the PRISMA 2020 flow diagram for new systematic reviews. Three studies met the inclusion criteria, and all of them present a moderate risk of bias (score 6). Two studies found no statistical differences between heat-polymerized and CAD/CAM (milled) denture base materials when attached with different types of artificial teeth, while one study showed higher values of CAD/CAM (milled) denture base materials. Bonding agents ensure bonding strength at least similar to the conventional methods. In order to improve the quality of future studies, it would be advantageous to use a larger number of specimens with standardized dimensions and a blinded testing machine operator to decrease the risk of bias.

Effect of Different Etching Times on Pit-and-Fissure Sealant Micro-Shear Bond Strength to the Enamel of Primary Teeth

Successful clinical use of pit-and-fissure sealants relies on the sufficient etching of the enamel, field isolation and sealant retention. The etching time changes the physical and mechanical surface properties of the etched tooth tissues; therefore, it impacts both etching depth and the bond strength of sealants to the enamel. We examined if reducing the recommended 15 s etching time of primary teeth enamel affects the micro-shear bond strength (µSBS) of pit-and-fissure sealants. The cusps of forty non-carious, extracted human primary molars were separately etched for 8, 15 or 30 s. Then, a pit-and-fissure sealant was placed and light-cured. The µSBS values were evaluated and compared among the three groups. The mean µSBS values ± standard deviations were 34.68 ± 16.93, 34.19 ± 17.35 and 36.56 ± 16.57 MPa in the cusps etched for 8, 15 and 30 s, respectively. No statistically significant differences in µSBS were observed among the three test groups. In this study, we showed for the first time that the recommended etching time of primary teeth enamel may be reduced from 15 to 8 s without compromising the µSBS of the sealant. Further evaluations in a clinical setting are warranted.

Influence of different tooth etchants on bur-cut and uncut enamel

This study aimed to evaluate the effect of pre-etching for two-step self-etch adhesive bonding to bur-cut and uncut enamel. Bur-cut and uncut enamel surfaces were assigned to surface treatments of no etchant (CT), Enamel Conditioner (EC; Shofu, Kyoto, Japan), or K-etchant syringe (KE; Kuraray Noritake Dental, Tokyo, Japan). The bonded samples were thermal cycled and evaluated by microshear bond strength (μSBS). The adhesive interface after acid-base challenge and the conditioned enamel surfaces were morphologically analyzed using scanning electron microscopy (SEM). For bur-cut enamel, EC and KE pre-etching significantly improved μSBS. For uncut enamel, KE showed higher μSBS than EC. SEM observation revealed that only KE removed the prismless layer of the uncut enamel surface. EC could improve enamel bonding and appears to be a substitute for phosphoric acid, especially for bur-cut enamel. However, uncut enamel could not be effectively conditioned by EC with a lower bond strength than KE.

A Comparative Evaluation of Shear Bond Strength of Embrace WetbondTM Pit and Fissure Sealant with or without the Use of a Universal Dental Adhesive System [ScotchbondTM Universal Adhesive] Using Different Bonding Protocols: A Multiparametric In Vitro Study

Aim

To evaluate and compare the shear bond strength (SBS) of Embrace WetBondTM (EWS) Pit and Fissure Sealant (PF sealants) with or without the use of a universal dental adhesive system ScotchbondTM Universal Adhesive (SBU) using different bonding and curing protocols and to assess and compare the mode of failure as determined by visualization of the fractured surfaces of the test specimens after shear testing under an optical microscope at a magnification of 20×.

Materials and methods

A total of 85 samples were prepared for testing SBS on enamel on caries-free, extracted permanent human molars. The specimens were randomly divided into five groups based on different bonding and curing protocols. A knife-edge blade in a universal testing machine was used to perform the SBS test with a crosshead speed of 1 mm/minute. Then the mode of failure was assessed.

Statistical analysis

Results were analyzed using a one-way analysis of variance with Tukey's post hoc test and Chi-squared test. A probability value 0.05 (p ≤ 0.01) was regarded as significant.

Results

ScotchbondTM Universal Adhesive (SBU) in total-etch (TE) mode/etch-and-rinse (ER) mode with individual light curing of the sealant and adhesive showed the highest SBS to enamel (5.40 ± 2.51 MPa). A predominance of cohesive mode of failure was observed for all the test groups.

Conclusion

Embrace WetBondTM (EWS) PF sealants with SBU in the ER mode of application, with either curing mode, can be used as an alternative to a conventional technique for sealant placement for improving interfacial bond strength to enhance sealant retention and efficacy.

Clinical significance

Embrace WetBondTM (EWS) PF sealants with SBU in the ER mode of application can be used as an alternative to a conventional technique for sealant placement for improving interfacial bond strength.

How to cite this article

Swathy SR, Naidu J. A Comparative Evaluation of Shear Bond Strength of Embrace WetbondTM Pit and Fissure Sealant with or without the Use of a Universal Dental Adhesive System [ScotchbondTM Universal Adhesive] Using Different Bonding Protocols: A Multiparametric In Vitro Study. Int J Clin Pediatr Dent 2023;16(1):48-53.

Bond strength between temporary 3D printable resin and conventional resin composite: influence of cleaning methods and air-abrasion parameters

OBJECTIVES

The influence of different cleaning methods, air-abrasion parameters, and aging on shear bond strength (SBS) and tensile bond strength (TBS) of 3D resin luted to composite resin.

MATERIALS AND METHODS

Nine hundred resin substrates were 3D printed (D20II, Rapid Shape) and cleaned with either isopropanol (ISO), butyldiglycol-based solution (BUT), or centrifugation (CEN). After 24-h storage in 37 °C water, specimens were air-abraded (mean particle size 50 µm; n = 60) with either alumina at 0.1 MPa (AL0.1) or 0.4 MPa (AL0.4) and glass pearls at 0.1 MPa (GP0.1) and 0.4 MPa (GP0.4) or conditioned with visio.link (control) and luted with PanaviaV5. Initially (24 h, 37 °C water storage) or after aging (10,000 thermal cycles), SBS and TBS were measured, and fracture types were examined. Surface free energy (SFE) and roughness (Ra) were determined after air-abrasion. Kolmogorov-Smirnov, Kruskal-Wallis H, Mann-Whitney U, chi-square, and partial eta-squared were computed.

RESULTS

SBS measurements presented higher values than TBS (p < 0.001-0.033). Within the pretreatment groups, CEN showed the highest SBS and TBS values compared to cleaning with ISO or BUT (p < 0.001-0.040). Pretreatment with GP0.1 displayed the lowest bond strength values (p < 0.001-0.049), and mostly adhesive fractures occurred. The highest Ra values (p < 0.001) were observed for AL0.4 pretreatment.

CONCLUSIONS

Pretreatment with AL0.4 and the control group mainly presented the highest bond strength values. Thermocycling had a positive effect on the bond strength.

CLINICAL RELEVANCE

According to this study, 3D-printed restorations should be pretreated with AL0.4 or with visio.link before adhesive luting, regardless of their cleaning.

Shear Bond Strength and Color Stability of Novel Antibacterial Nanofilled Dental Adhesive Resins

Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained by dispersing nitrogen and fluorine co-doped titanium dioxide nanoparticles (NF_TiO2, 10%, 20% or 30%, v/v%) into OptiBond Solo Plus (OPTB). Dentin surfaces were wet-polished (600-Grit). Specimens (n = 5/group) of Tetric EvoCeram were fabricated and bonded using either OPTB or experimental (OPTB + NF_TiO2) adhesives. Specimens were stored in water (37 °C) for twenty-four hours (T1), three months (T2), and six months (T3). At T1, T2, or T3, specimens were removed from water storage and were tested for SBS. Disc-shaped specimens (n = 10/group; d = 6.0 mm, t = 0.5 mm) of adhesives investigated were fabricated and subjected to thermocycling (10,000 cycles, 5−55 °C, 15 s dwell time). Specimens’ colors were determined with a VITA Easyshade® V spectrophotometer (after every 1000 cycles). SBS data was analyzed using two-way ANOVA and post-hoc Tukey tests, while CS data was analyzed using one-way ANOVA and post-hoc Tukey tests (α = 0.05). Mean values of SBS ranged from 16.39 ± 4.20 MPa (OPTB + 30%NF_TiO2) to 19.11 ± 1.11 MPa (OPTB), from 12.99 ± 2.53 MPa (OPTB + 30% NF_TiO2) to 14.87 ± 2.02 (OPTB) and from 11.37 ± 1.89 (OPTB + 20% NF_TiO2) to 14.19 ± 2.24 (OPTB) after twenty-four hours, three months, and six months of water storage, respectively. Experimental materials had SBS values that were comparable (p > 0.05) to those from OPTB independently of nanoparticle concentration or time-point considered. Experimental materials with higher NF_TiO2 concentrations had less intense color variations and were more color stable than OPTB even after 10,000 thermocycles. In combination, the results reported have demonstrated that experimental adhesives can establish strong and durable bonds to human dentin while displaying colors that are more stable, thereby suggesting that the antibacterial nanotechnology investigated can withstand the harsh conditions within the oral cavity without compromising the esthetic component of dental restorations.

The effect of desensitizing agents on the bond strength of dentin bonding agents: A systematic review

Background

Dentinal hypersensitivity (DH) is a common dental problem and is treated non-invasively using topical application of various desensitizing agents. When there is loss of tooth structure or tooth preparation is to be followed by a bonded restoration, it requires application of dentin bonding agent. However, the effect of desensitizers on bond strength is still controversial.

Aim and Objective

To evaluate the influence of different desensitizing agents on the bond strength of the dentin bonding agents.

Methods and Materials

PICO strategy was used to formulate the research question. In-vitro studies conducted on human teeth to evaluate the bond strength of dentin bonding agent following the application of desensitizing agent were included. Electronic databases PubMed and Cochrane and google scholar were searched using search terms alone or in combination from the year 2010 till 2020. Search was conducted using the key words and MeSH terms (hypersensitivity, bond strength, dental adhesives, dentin bonding agents). The title and abstract were read to verify the inclusion and exclusion criteria and if further any details required, full article was accessed to check the criteria and then included or excluded. Data extraction was done using a customized data extraction form. The risk of bias was evaluated using modified Cochrane Collaboration Quality Assessment tool.

Results

Total no of studies identified in the search were 146, after scrutiny 23 articles were eligible to be included in this study. Out of 23 articles, 17 articles were of medium bias and 6 articles were of high risk after risk of bias assessment.

Conclusion

According to the various articles included in this study, GLUMA and 8.0%Arginine and CaCO3 when used as desensitizing agents along with different bonding agents, were found to be highly compatible without interfering with the bond strength of the dentin adhesives.

Comparative evaluation of adhesion of glass fiber post to the root dentin after surface treatment of post and using universal bonding agent: An in vitro study

Objective

The purpose of the study is the evaluation and comparison of surface roughness and bond strength of glass fiber post (GFP) after different types of surface treatment and the application of a universal bonding agent.

Materials and Methods

Forty GFPs were divided into four groups based on surface treatment: Group I, silane coupling agent application for 60 s; Group II, air abrasion with 30 μm silicon dioxide powder particles in 2.5 bar pressure from 2 cm distance for 10 s, followed by silane coupling agent application; Group III, 9% hydrofluoric acid application for 10 s, rinsed and air-dried, followed by silane coupling agent application; and Group IV, silane coupling agent application, followed by universal bonding agent application. Surface roughness evaluation is done by a profilometer. All posts were cemented in the root of the maxillary central incisor with resin cement. After that, root was placed in an acrylic mold, and the external end part of the post was mounted on another acrylic mold. Pull-out bond strength was measured by a universal testing machine.

Results

Highest surface roughness and bond strength values were found in Group II.

Conclusion

Pretreatment of GFP increases the surface roughness of post as well as bond strength of post to root dentin. There is a correlation between surface roughness and bond strength. However, the use of only universal bonding agent also showed comparable pull-out bond strength of GFP, which means only use of universal bonding agent also a new alternative as pretreatment of GFP and helps in increase in bond strength.

The Effect of a 10-MDP-Based Dentin Adhesive as Alternative for Bonding to Implant Abutment Materials

Bonding to different dental restorative materials is challenging. This study aimed to evaluate the effect of a 10-MDP-based dentin adhesive on the shear bond strength (SBS) of self-adhesive resin cement (RC) to implant abutment materials. One hundred and twenty specimens were obtained from zirconia (ZO), cobalt-chromium alloy (CoCr), and commercially pure titanium (Ti), which were treated as follows (n = 10): control group-non-treated (CG), 10-MDP-based dentin adhesive (SB), light-cured SB (SB-LC), and zirconia primer (ZP). Blocks of RC were buildup and, after 24 h, were tested for bond strength. Data of SBS (MPa) were submitted to two-way ANOVA and Tukey test (α = 0.05). There was no difference in SBS among materials for CG and ZP, higher SBS were recorded for Ti SB and Ti SB-LC compared to ZO upon the same surface treatments. For the comparisons among treatments, SB-LC showed the highest SBS for CoCr. For ZO and Ti, higher SBS were recorded with SB and SB-LC. No cohesive failures were observed. It was concluded that the surface treatment with 10-MDP-based materials increased the bond strength of the resin cement to abutment materials, which showed to be material dependent.

Adhesion of Resin to Lithium Disilicate with Different Surface Treatments before and after Salivary Contamination—An In-Vitro Study

The salivary contamination occurring at the try-in procedures of lithium disilicate (LDS) can jeopardize their bond strength. Various laboratory reports have concluded that applying 37% phosphoric acid (H₃PO₄) could be considered as a predictable way of removing salivary contaminants. An experimental method that consists of sealing the intaglio of the ceramic restorations with a layer of cured adhesive could allow consequent time saving for dental practitioners. It is, besides, necessary to establish an optimal decontamination protocol. Hence, this study aimed to determine the most efficient surface treatment, before and after salivary contamination, by comparing the adhesion between resin and LDS. In order to do so, five groups of ten specimens (n = 10) each underwent the different types of surface treatments before bonding, followed by 2500 cycles in the thermocycler. A shear bond strength (SBS) test was then conducted on a universal testing machine (YLE GmbH Waldstraße Bad König, Germany), followed by a fracture-type analysis on an optical microscope (Olympus BX53, Shinjuku, Tokyo, Japan). Statistical analysis was set with a level of significance of α = 0.05. The surface treatment significantly affected the SBS results. The decontamination with HF (12.59 ± 2.71 MPa) and H₃PO₄ (13.11 ± 1.03 MPa) obtained the highest values, silanizing only before contamination obtained intermediate values (11.74 ± 3.49 MPa), and silanizing both before and after the salivary contamination (10.41 ± 2.75 MPa) along with applying a bonding agent before contamination (9.65 ± 1.99 MPa) resulted in the lowest values. In conclusion, H₃PO₄ proved to be efficient, thus, allowing the practitioner to avoid the clinical use of HF; it can, therefore, be considered as a valid alternative. Presilanization and resilanization of specimens, along with applying a bonding agent before contamination, did not yield satisfying results.

Shear Bond Strength of Self-Adhesive Flowable Resin Composite

This study aimed to evaluate the shear bond strength of self-adhesive flowable resin composite on both enamel and dentin and investigate whether surface pretreatment with a phosphoric acid etch affects the bond strength. In this in vitro study, 80 sound human premolars were flattened to create (40) uniform enamel (E) and (40) dentin (D) surfaces. Groups were divided according to surface pretreatment: E1 : Scotchbond^™ Universal Etchant + Single Bond Universal Adhesive + Filtek^™ Z350 XT flowable composite; E2: Single Bond Universal self-etch adhesive + Filtek Z350 XT flowable composite; E3 : Scotchbond Universal Etchant + Fusio Liquid Dentin self-adhesive flowable composite; E4: Fusio Liquid Dentin self-adhesive flowable composite; D1 : Scotchbond Universal Etchant + Single Bond Universal Adhesive + Filtek Z350 XT flowable composite; D2: Single Bond Universal self-etch adhesive + Filtek Z350 XT flowable composite; D3: Scotchbond Universal Etchant + Fusio Liquid Dentin self-adhesive flowable composite; D4: Fusio Liquid Dentin self-adhesive flowable composite. After 2500 thermal cycles, the SBS was measured with a universal testing machine. One-way analysis of variance and Tukey's test for multiple comparisons were used to compare results. Two-way ANOVA was done to observe the significance of interaction between the type of surface and treatment. The maximum (49.38 ± 1.23 MPa) and minimum (21.41 ± 5.27 MPa) SBS values were noted in groups D1 and E2, respectively. Shear bond test results showed that self-adhesive flowable composite exhibited similar shear bond strengths on enamel and dentin and the bond strength improved with selective acid etching.

Physicochemical Properties of Dentine Subjected to Microabrasive Blasting and Its Influence on Bonding to Self-Adhesive Prosthetic Cement in Shear Bond Strength Test: An In Vitro Study

The aim of this in vitro study was to assess the influence of microabrasive blasting on the physicochemical properties of dentine and shear bond strength (SBS) of self-adhesive resin cement (Maxcem Elite, Kerr, Orange, CA, USA) bonded to the dentine surface. Ninety cylindrical specimens with exposed dentine of human teeth were prepared and divided into three randomized, parallel sample sets A, B, and C. Groups B and C were subjected to abrasive blasting using a micro-sandblasting device (Microetcher IIa, Danville Materials, Carlsbad, CA, USA) with two gradations of Al₂O₃ abrasives (Group B, abrasion with a gradation of 50 μm; group C, abrasion with a gradation of 27 μm). SEM imaging, profilometry, chemical composition analysis, contact angle measurements, surface free energy, and SBS tests were performed. The resulting data were statistically analyzed using the Statistica software (ver. 13.3, Tibco Software Inc., Palo Alto, CA, USA). Microabrasive blasting caused changes in surface topography, structural features, and the connection strength between the dentin surface and self-adhesive prosthetic cement. Air microabrasion through the multifactorial positive reorganization of the treated surface of dentine is recommended as a pretreatment method in fixed prosthodontics adhesive cementation protocols.

Effect of Conventional Adhesive Application or Co-Curing Technique on Dentin Bond Strength

The aim of this in vitro study was to assess the effect of two different adhesive application methods on shear dentin bond strength (ISO 29022) using three various adhesive systems. A mid-coronal section of 77 intact third human molars with fully developed apices was made to create flat bonding substrates. The materials used in the study were Excite F (Ivoclar Vivadent), Prime&Bond Universal (Dentsply Sirona) and G-Premio Bond (GC). The application of each adhesion system was performed in two different ways. In the first group, the bonding agent was light cured immediately after the application (conventional method), while in the second group the adhesive and composite were cured concurrently (“co-curing” method). A total of 180 specimens were prepared (3 adhesives × 2 method of application × 30 specimens per experimental group), stored at 37 °C in distilled water and fractured in shear mode after 1 week. Statistical analysis was performed using ANOVA and Weibull statistics. The highest bond strength was obtained for Prime&Bond conventional (21.7 MPa), whilst the lowest bond strength was observed when co-curing was used (particularly, Excite F 12.2 MPa). The results showed a significant difference between conventional and co-curing methods in all materials. According to reliability analysis, the co-curing method diminished bond reliability. Different application techniques exhibit different bond strengths to dentin.

Micro versus Macro Shear Bond Strength Testing of Dentin-Composite Interface Using Chisel and Wireloop Loading Techniques

Shear bond strength (SBS) testing is a commonly used method for evaluating different dental adhesive systems. Failure mode analysis provides valuable information for better interpretation of bond strength results. The aim of this study was to evaluate the influence of specimen dimension and loading technique on shear bond strength and failure mode results. Eighty macro and micro flowable composite cylindrical specimens of 1.8 and 0.8 mm diameter, respectively, and 1.5 mm length were bonded to dentinal substrate. Four study groups were created (n = 20): Macroshear wireloop, Gp1; Microshear wireloop, Gp2; Macroshear chisel, Gp3; and Microshear chisel, Gp4. They were tested for SBS using chisel and wireloop loading devices followed by failure mode analysis using digital microscopy and SEM. Two- and one-way ANOVA were used to compare stress at failure values of different groups while the Kruskal–Wallis test was used to compare between failure modes of the tested groups. Gp4 recorded the highest mean stress at failure 54.1 ± 14.1 MPa, and the highest percentage of adhesive failure in relation to the other groups. Specimen dimension and loading technique are important parameters influencing the results of shear bond strength. Micro-sized specimens and chisel loading are recommended for shear testing.

[Laboratory methods for measuring adhesive bond strength between restoration materials and hard tooth tissues]

THE AIM OF THE STUDY

Was to review laboratory methods measuring the bond strength of adhesive dental materials to hard tooth tissues. The paper points out the impact of test conditions on the measured strength of adhesive bond to dentine and enamel. Various in vitro studies are discussed, including the analyses of fracture surfaces and test-induced stresses. These studies are found to be helpful to identify particularities, advantages, and limitations of each approach. We present a systematic picture of available bond-strength data aimed at revealing general trends in adhesive performance. No clear superiority of any particular method for determining the bond strength between restoration materials and tooth tissues can be identified on the basis of reviewed literature. Therefore, no single universal approach can be at present proposed for determining the strength of adhesive bond.

Effect of Multiple Enamel Surface Treatments on Micro-Shear Bond Strength

Objectives: The aim of this study was to evaluate the effect of different enamel surface treatments on the micro-shear bond strength. Materials and methods: Sixty-four approximal surfaces from freshly extracted molars were randomly assigned to eight groups, according to combinations of the following enamel surface treatments: ground or unground, 37.5% phosphoric acid etching time of 15 or 30 s, and with or without primer application. The same bonding agent (Optibond FL™ Adhesive, Kerr) was then used for all groups, and a 1.8 mm diameter resin composite (Harmonize™, Kerr) cylinder was built up on the bonded surface. Samples underwent a shear force test at a crosshead speed of 1 mm/min until failure. Bond strength was calculated, and failure modes were inspected under an optical microscope. Results: Bond-strength values ranged from 8.2 MPa for 15 s etched unground enamel with primer application to 19.6 MPa for 30 s etched ground enamel without primer application. ANOVA and Fisher’s LSD post hoc tests revealed significant differences between the groups. Conclusions: Etching time and grinding have a statistically significant effect on the micro-shear bond strength of a three-step etch-and-rinse adhesive system on enamel. Primer application does not seem to be beneficial for enamel adhesion.

Evaluation of the Interfaces between Restorative and Regenerative Biomaterials Used in Vital Pulp Therapy

BACKGROUND

Calcium-silicate-based cements (CSC) have gained an increasing scientific and clinical relevance, enabling more conservative approaches, namely pulp preservation and regeneration therapies. This research aims to study the influence of four clinical variables on the interfaces between CSC and composite adhesive restoration, concerning shear bond strength (SBS) and ultra-morphological patterns.

METHODS

SBS tests were performed in 320 specimens divided in 16 groups (n = 20) according to: two CSC (NuSmile^® NeoMTA, Biodentine^TM); two adhesive systems (Clearfil^TM SE Bond 2 (CSEB2), Clearfil^TM Universal Bond Quick (CUBQ)); optional application of an additional hydrophobic bonding layer (HBL); two restoration times (immediate, seven days). Scanning electron microscopy (SEM) was performed to conduct the ultra-morphology interface analysis in 32 deciduous molars prepared and randomly allocated into the 16 groups.

RESULTS

Globally, SBS tests showed higher bond strength of CUBQ compared to CSEB2 (p < 0.001), as with an additional HBL application (p = 0.014) and delayed restoration (p < 0.001). SEM showed the interpenetration between adhesive systems and CSC forming a hybrid layer, whose depth and thickness depended on the restoration time and adhesive strategy.

CONCLUSIONS

The independent clinical variables adhesive system, application of an additional HBL and restoration time affected the bond performance and ultra-morphological interface between composite adhesive restoration and CSC.

The effect of diabetes mellitus on the shear bond strength of composite resin to dentin and enamel

Diabetes mellitus might be linked to the deterioration of certain physical properties of dentin and enamel. This study aimed to determine the effect of two types of diabetes on the shear bond strength of enamel and dentin, by using the single bond universal bonding system. Sixty specimens [from 15 teeth; 5 from each group-non-diabetic (ND), Diabetic type I (D1), and Diabetic type II (D2)], were prepared with equal amounts of dentin (n = 5) and enamel (n = 5). Enamel specimens (E20) were etched with 37% phosphoric acid, for 20 s, and dentin specimens (D15) were etched for 15 s. A standard shear bond strength test was performed on all specimens. Their failure modes were also studied under a scanning electron microscope, and the data were analyzed by using ANOVA and Post Hoc Tukey's test (a = 0.050). For the enamel groups, significant differences were only noticed between the ND and D1 (P < 0.050) groups, and between the ND and D2 (P < 0.050) groups. In the dentin groups, there was a significant difference only between the ND and D1 (P < 0.050) groups. The micrographs showed that the ND group had the highest number of specimens with cohesive failure and D1 had the highest number of specimens with adhesive failure. It can be concluded that both types of diabetes reduce the shear bond strength of composite resin on dentin and enamel. However, it seems that the negative effect of diabetes on shear bond strength of dental composite resin is more drastic in individuals with type I diabetes as compared with type II.

Rheological Properties, Surface Microhardness, and Dentin Shear Bond Strength of Resin-Modified Glass Ionomer Cements Containing Methacrylate-Functionalized Polyacids and Spherical Pre-Reacted Glass Fillers

The aim of this study was to prepare experimental resin-modified glass ionomer cements (RMGICs) containing low levels of hydroxyethyl methacrylate (HEMA) for pulp protection. Liquid and powder phases of the experimental RMGICs were polyacid functionalized with methacrylate groups and spherical pre-reacted glass fillers (SPG). Two types of liquid phase containing 0 wt. % HEMA (CM liquid) or 5 wt. % HEMA (CMH liquid) were formulated. The experimental RMGICs were prepared by mixing SPG fillers with CM liquid (F1) or CMH liquid (F2). Rheological properties were examined using a strain-controlled rheometer (n = 5). The Vickers microhardness (n = 5) and dentin shear bond strength (SBS) (n = 10) of the materials were tested. Commercial pulp protection materials (Vitrebond and TheraCal LC) were used as comparisons. The viscosity and surface microhardness of F1 (22 m Pa·s, 18 VHN) and F2 (18 m Pa·s, 16 VHN) were significantly higher than those of Vitrebond (6 mPa·s, 6 VHN) and TheraCal (0.1 mPa·s, 7 VHN). The SBS of F1 (10.7 MPa) and F2 (11.9 MPa) was comparable to that of Vitrebond (15.4 MPa) but higher than that of TheraCal LC (5.6 MPa). The addition of 5 wt. % HEMA showed no significant effect on viscosity, surface microhardness, or SBS of the experimental RMGICs. The experimental materials showed higher viscosity and microhardness but similar SBS when compared with the commercial RMGIC.

The Bond Strength and Antibacterial Activity of the Universal Dentin Bonding System: A Systematic Review and Meta-Analysis

Streptococcus mutans (S. mutans) is a group of viridans mostly located in oral flora among the wide and biodiverse biofilm. It plays a significant role not only in caries formation but also triggering intracerebral haemorrhage. The durable and stable bond interface, besides bacteria elimination, is one of the crucial factors influencing the resin composite restoration performance. This study aimed to evaluate universal adhesives (UAs) with regard to in vitro bond strength to dentin, and the inhibition of the S. mutans growth and compare them with UAs modified with antimicrobial agents through a systematic review and meta-analysis. Two reviewers performed a literature search up to April 2021 in 5 electronic databases: PubMed MedLine, Scielo, ISI Web of Science, Scopus, and EMBASE. Only in vitro studies reporting the effect of modifying UAs with antimicrobial agents on the bond strength to dentin and/or on the inhibition of the S. mutans were included. Analyses were 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 evaluated following the parameters of a previous systematic review. A total of 1716 potentially relevant publications were recognized. After reviewing the title and abstract, 16 studies remained in the systematic review. From these, a total of 3 studies were included in the meta-analysis. Since data from the studies included in the antimicrobial outcome included zero values, they could not be meta-analysed. Including 0 values in the analysis will lead to several biases in the analysis, so these data were discarded. The antibacterial effect against S. mutans of UAs modified with antimicrobial agents was higher than the non-modified adhesive systems. Within the limitations of the present study, the bond strength of UAs to dentin could be improved by using antimicrobial agents. The UAs modified with antibacterial agents showed a decrease in the viability of S. mutans biofilm, among the adhesives tested. However, there are not enough valid data on antibacterial properties of modified UAs; therefore, more well-designed research on these materials is needed.

Bond Integrity of Titanium Surface to Resin Cement After Conditioning with Different Photobiomodulataion Therapy (PBT)

The aim of the present study was to evaluate the efficacy of interfacial bonding between resin cement and titanium alloy conditioned with different Photobiomodulataion Therapy (PBT) in comparison with conventional regimes. Seventy-five samples of titanium bar were segmented polished; and based on conditioning regime divided into five groups (15 each specimens). Group 1: No treatment (control), Group 2: Sand blasting with 120 µm Al2O3, Group 3: Er,Cr:YSGG (ECL), Group 4: Er:YAG laser (EYL), Group 5: Nd:YAG laser (NYL). After different conditioning regimes, resin cement was mixed and applied. All specimens were thermocycled for 500 cycles and positioned on universal testing machine for shear bond strength testing. Modes of failure was assessed by a single examiner using stereomicroscope at 40× magnification. Three pairs of specimens in each group were sputter coated and scanning electron microscope (SEM) images were taken at 1000× magnification using 20 Kv. The highest SBS values were observed in group 2 (14.25±2.29 MPa) and the lowest bond values were displayed in group 1 (6.98 ±0.59 MPa). Titanium alloy abutments conditioned with different laser prototypes ECL (11.22±1.40 MPa), EYL (9.29±1.22 MPa) and NYL (9.12 ±1.84 MPa) exhibited comparable SBS (p > 0.05). Adhesive failures were primarily dominant among all experimental groups. Photo-biomodulation in the form of ECL lasers has the potential to be used as a supplement to sandblasting procedure in conditioning of cement retained titanium alloy implant abutments.

Comparison of shear bond strengths of different types of denture teeth to different denture base resins

PURPOSE

To determine the shear bond strengths of different denture base resins to different types of prefabricated teeth (acrylic, nanohybrid composite, and cross-linked) and denture teeth produced by computer-aided design/computer-aided manufacturing (CAD/CAM) technology.

MATERIALS AND METHODS

Prefabricated teeth and CAD/CAM (milled) denture teeth were divided into 10 groups and bonded to different denture base materials. Groups 1-3 comprised of different types of prefabricated teeth and cold-polymerized denture base resin; groups 4-6 comprised of different types of prefabricated teeth and heat-polymerized denture base resin; groups 7-9 comprised of different types of prefabricated teeth and CAD/CAM (milled) denture base resin; and group 10 comprised of milled denture teeth produced by CAD/CAM technology and CAD/CAM (milled) denture base resin. A universal testing machine was used to evaluate the shear bond strength for all specimens. One-way ANOVA and Tukey post-hoc test were used for analyzing the data (α=.05).

RESULTS

The shear bond strengths of different groups ranged from 3.37 ± 2.14 MPa to 18.10 ± 2.68 MPa. Statistical analysis showed significant differences among the tested groups (P<.0001). Among different polymerization methods, the lowest values were determined in cold-polymerized resin.There was no significant difference between the shear bond strength values of heat-polymerized and CAD/CAM (milled) denture base resins.

CONCLUSION

Different combinations of materials for removable denture base and denture teeth can affect their bond strength. Cold-polymerized resin should be avoided for attaching prefabricated teeth to a denture base. CAD/CAM (milled) and heat-polymerized denture base resins bonded to different types of prefabricated teeth show similar shear bond strength values.

Repair strength and surface topography of lithium disilicate and hybrid resin ceramics with LLLT and photodynamic therapy in comparison to hydrofluoric acid

AIM

The aim was to compare the repair bond strength and surface topography of lithium disilicate ceramics (LDC) and hybrid resin ceramics (HRC) using different surface conditioning treatments [low level laser therapy (LLLT), photodynamic therapy (PDT), hydrofluoric acid (HF) with silane and air abrasion (AA) and silane].

MATERIAL AND METHOD

Sixty specimens each of LDC and HRC were used. Discs were prepared for each group (6 × 2 mm), conditioned using different regimes. Specimens in group 1 and 5 were laser irradiated using Er,Cr:YSGG (ECYL), group 2 and 6 were conditioned using methylene blue photosensitizer (PDT), group 3 and 7 surface was treated with hydrofluoric acid and silane (HFA-S), group 4 and 8 conditioned with Al₂O₃ air abrasion and silane (AA-S). A Porcelain Repair Kit was used according to manufacturer recommendation in all samples. Peak universal bond adhesive was rubbed on ceramic surface and then bonded with composite resin. For shear bond strength testing the specimens were placed in a universal testing machine. A stereomicroscope at 40x magnification was used to analyse failure pattern. Five specimens in each group after surface treatment were evaluated for surface changes and topography using scanning electron microscopy. The mean repair bond strength was calculated using ANOVA and Tukey's post hoc test at a significance level of (p < 0.05).

RESULT

The highest repair bond strength was observed in group 3 (LDC) (20.57 ± 3.58 MPa) (HFA-S), whereas, the lowest score was displayed in Group 2 (LDC) using methylene blue photosensitizer (MBPS) (12.18 ± 1.08 MPa). Similarly, in HRC the highest repair SBS was presented in group 8 (AA-S) (20.52 ± 2.51 MPa) and the lowest SBS values were exhibited by PDT treated group 6 (13.22 ± 0.62 MPa).

CONCLUSION

A combination of mechanical and chemical surface treatments should be used in order to achieve adequate repair bond strength between resin composites and ceramic interface of LDC and HRC.

Effect of different surface treatments and multimode adhesive application on the Weibull characteristics, wettability, surface topography and adhesion to CAD/CAM lithium disilicate ceramic

This paper aims to evaluate the effect of different surface treatments on surface topography, wettability, and shear bond strength of resin cement to glass ceramic.

Surface treatment of RMGIC to composite resin using different photosensitizers and lasers: A bond assessment of closed Sandwich restoration

AIM

The aim of present study was to assess and compare different conditioning methods (laser, PDT and conventional) on shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) bonded to composite (sandwich technique).

MATERIAL AND METHODS

Fifty specimens were prepared from RMGIC and were packed in a teflon mould placed on glass slab. Through each of the glass slab the cement was light cured for 20 s. Now samples were randomly allocated into five groups (n = 10) according to pre-treatment protocols. In group 1 RMGIC were conditioned with MBP using PDT, Samples in group 2 treated with Er,Cr:YSGG (ECYL), group 3 pre-treated with Nd:YAG laser (NYL), samples in group 4 surface conditioned with air abrasion (AA) and group 5 conditioned with 37 % phosphoric acid (PA). Specimens after conditioning were rinsed with distilled water. Adhesive Adper Single Bond 2 was applied on treated surface of RMGIC and cured. Teflon mold was utilized to hold the composite Filtek Z250 in an incremental technique. For SBS testing all specimens were placed under shear knife edge at 1 K N at a speed of 0.5mm2 until bond failure. Optical microscope was used to evaluate failure pattern at 10x magnification. The data of SBS in Megapascal were subjected to statistical test. Analysis of variance was followed by Post hoc test with level of significance at 5 %.

RESULT

The maximum SBS was found in group 5 RMGIC conditioned with 37 % PA (16.45 ± 0.32 MPa). Whereas, group 1 (MBP, PDT) demonstrated significantly lower bond integrity (9.82 ± 1.08 MPa) compared to all experimental groups. Bond integrity of RMGIC surface treated with MBP, PDT (9.82 ± 1.08 MPa), group 3 lased with NYL (11.47 ± 0.53 MPa) and samples in group 4 conditioned with AA (11.23 ± 0.47 MPa) were comparable (p > 0.05).

CONCLUSION

ECYL has a potential to be used for conditioning of RMGIC prior to composite restoration (sandwich technique). MBP at 100 mg/L deteriorates SBS of composite to RMGIC.

Effect of prolonged application of single-step self-etching primer and hydrofluoric acid on the surface roughness and shear bond strength of CAD/CAM materials

This in vitro study aimed to assess the influence of different concentrations and durations of hydrofluoric acid (HF) and Monobond Etch & Prime (MEP) etching on the surface roughness (R_a ) of different CAD/CAM materials and on the shear bond strength (SBS) of a self-adhesive resin bonded to the materials. Seventy specimens of hybrid ceramic, leucite-based glass-ceramic, lithium disilicate glass-ceramic, and zirconia-reinforced lithium silicate glass-ceramic were prepared and divided into seven groups according to the surface treatments: Control (C); MEP etching for 60 (MEP₆₀ ) and 120 (MEP₁₂₀ ) s; 5% HF etching for 60 (HF-5%₆₀ ) and 120 (HF-5%₁₂₀ ) s; 9.5% HF etching for 60 (HF-9.5%₆₀ ) and 120 (HF-9.5%₁₂₀ ) s. The R_a was measured using a 3D profilometer. All groups were treated with a universal primer except for the C, MEP₆₀ , and MEP₁₂₀ groups. A self-adhesive resin cement was bonded to all specimens, and the bond strengths were measured using a universal testing machine. All surface treatments increased both R_a and SBS values compared to the control in each material. Neither the duration of surface treatments nor the HF acid concentrations had a statistically significant effect on SBS. Within the limitations of this experimental study, it can be concluded that Monobond Etch & Prime may be a preferable method to achieve high bond strength values.

Influence of photodynamic therapy and different lasers Er,Cr:YSGG and Er,YAG on dentin conditioning bonded to conventional and bioactive cement

AIM

The aim of the present study was to evaluate the bond integrity of bioactive cement (BA_c) in contrast to conventional cement Calibra (C) after dentin treated with different surface conditioners (PDT, EYL, ECL) MATERIALS AND METHODS: Sixty non-carious permanent mandibular molars were disinfected and embedded in acrylic resin till cement-o-enamel junction. For homogeneity the buccal surface were grounded and polished. Samples were categorized into three main groups based on conditioning technique. Samples in group 1 and 2 dentin conditioned with Er,Cr:YSGG (ECL), group 3 and 4 surface treated with Er:YAG (EYL) and group 5 and 6 treated with photodynamic therapy (PDT).On conditioned surface bonding agent was applied and light cured. Samples from group 1,3,5 were bonded to Calibra (C). Whereas, specimens in group 2,4,6 were conditioned with bioactive cement (BA_c) and subjected to ageing followed by shear bond strength testing (SBS) in universal testing machine. To detect significance difference between means of different groups analysis of variance (ANOVA) was performed followed by Tukey's post-hoc tests.

RESULTS

The maximum SBS was displayed in group 1, dentin conditioned with ECL and bonded to C (20.23 ± 0.47 MPa). Whereas, group 6, PDT of dentin to BA_c demonstrated lowest bond integrity among experimental groups (12.97 ± 0.25 MPa). Bond strength of group 1, ECL-C (21.55 ± 3.08 MPa) and group 3 EYL-C (19.11 ± 0.65 MPa) were comparable (p > 0.05). Group 5 samples treated with PDT, MB-C (13.41±0.32 MPa) and group 6, MB-BA_c (12.97 ± 0.25 MPa) were also comparable (p > 0.05) CONCLUSION: BAc bonded to dentin after surface conditioning with ECL, EYL and PDT presented lower SBS in comparison to conventional cement C. Further studies are required to extrapolate the current findings.

Gomes MG, Amaral FLB, G. França FM, Basting RT, Bandeca MC, Diniz RS, Gonçalves LM, de J. Tavarez RR, Turssi CP. Aging Protocols and Their Effects on Bond Strength of Total-Etch and Self-Etch Adhesive Systems to Dentin

Objective:

This study investigated whether different aging protocols have effects on the bond strength of total-etch and self-etch adhesive systems to dentin substrate.

Methods:

Molars were sectioned exposing the dentin, which was submitted to restorative procedures using two-step total-etch (ASB, Adper SingleBond2), two-step self-etch (CLF, Clearfil SEBond), or one-step self-etch (OPT, Optibond All-in-One) system and resin composite. The obtained blocks were sectioned to result in sticks to be submitted to bond strength and failure mode tests after 24h storage in distilled water (DW), or 180-day aging protocols in DW, artificial saliva (AS), citric acid (CA), or thermal cycling (TC). The types of failures were classified as adhesive, cohesive in dentin, cohesive in composite resin, and mixed. Data were analyzed using ANOVA followed by Tukey’s test (α=5%). The failure modes were descriptive under the relative frequencies form.

Results:

It was observed that ASB presented the higher bond strength(p<0.05), while CLF and OPT did not demonstrate differences between them(p>0.05) after 24h. The bond strength obtained with ASB significantly overcame that of OPT when stored in DW or AS for 180 days (p<0.001). In these storing mediums, ASB did not differ from CLF(p>0.05), while in CA or TC the values of CLF were significantly lower (p<0.001). In TC aging, the values presented by OPT did not differ from ASB(p>0.05), both of which had higher values than CLF(p<0.05). The predominant failure mode was adhesive.

Conclusion:

For the two-step total-etch and two-step self-etch adhesives, the influence of aging in AS and TC was equivalent to that of storage in DW. The most deleterious effects occurred in CA, a situation in which self-etch adhesives displayed worse performance than the conventional type.

The impact of non-thermal plasma on the adhesion of polyetherketoneketone (PEKK) to a veneering composite system

The PEKK material can be used in prosthodontics for framework manufacturing and is commonly laminated with veneering composites to achieve a better esthetics. Various surface treatment methods including sandblasting, etching, laser and cold plasma treatments were reported to enhance the adhesive properties of dental polymers. Both tensile and shear bond test were employed to quantify the bond strength between PEKK and veneering composites. The present in vitro study aims to evaluate the influence of acetylene, argon, air, nitrogen and oxygen plasma on the shear bond strength between PEKK and one veneering composite. Firstly, to determine which bond test type should be applied, n = 40 PEKK specimens were treated with argon plasma. Both shear and tensile bond tests were performed and compared to the control group (n = 40). In shear bond testing, values were 8.14 ± 1.70 MPa for Argon plasma while 5.83 ± 1.42 MPa for control group. In tensile bond testing, Argon plasma 1.50 ± 0.51 MPa while control group 0.58 ± 0.50 MPa. Afterwards n = 160 PEKK specimens were treated with rocatec sandblasting (n = 20), adhesive (n = 20), acetylene (n = 20), argon (n = 20), air (n = 20), nitrogen (n = 20), oxygen (n = 20) plasma types and compared to the untreated control group (n = 20) using shear bond strength test (SBS). Additionally surface roughness and scanning electron microscopy analyses were performed. The following SBS values were revealed: 10.22 ± 1.06 MPa for rocatec; 9.89 ± 3.08 MPa for acetylene, 9.16 ± 1.48 MPa for adhesive, 7.54 ± 1.52 MPa for argon, 7.09 ± 1.99 MPa for air, 7.03 ± 1.48 MPa for nitrogen, 5.69 ± 1.59 MPa for oxygen plasma types and 4.71 ± 1.54 MPa for the control group. All groups, except control group, showed SBS over 5 MPa, which means that they are suitable for the clinical application, according to ISO 10477. Acetylene showed the highest SBS among all plasma types (p < 0.0001), which was on a level of rocatec sandblasting group. Rocatec and acetylene groups demonstrated Ra values significantly different to the reference group (p < 0.0001). Plasma treatment especially with acetylene gas can be an effective more convenient surface treatment method for strengthening the bond strength between PEKK and veneering composites than traditional sandblasting/adhesive treatment.

Bond assessment of resin modified glass ionomer cement to dentin conditioned with photosensitizers, laser and conventional regimes

AIM

To assess different conditioning regimes on shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) bonded to dentin MATERIAL AND METHODS: Fifty non carious intact maxillary molars were cleaned, isolated and randomly divided into five groups (n = 10). Before randomization, dentin surface was exposed and finished. Samples in group 1 were conditioned with methylene blue photosensitizer (MBP) 50 mg/l and activated by photodynamic therapy (PDT), Group 2: surface treated with Er,Cr:YSGG (ECL), Group 3: surface conditioned with polyacrylic acid (PAA) (control), Group 4: surface conditioned with 17 % Ethylenediaminetetraacetic acid (EDTA), Group 5: surface conditioned with total etch (Optibond solo Plus). For SBS testing the samples were placed in universal testing machine. Fracture analysis of debonded surfaces were evaluated using stereomicroscope at 40x magnification. Means and standard deviations were calculated using analysis of variance (ANOVA) and Tukey's post hoc test at a significance level of (p < 0.05).

RESULTS

The maximum bond strength was found in group 5 conditioned with Optibond solo plus total etch (23.15 ± 3.21 MPa). Whereas, the lowest bond values were observed in group 1 treated with MBP (15.25 ± 1.54 MPa). Moreover, samples in group 2, group 3 and group 4 resulted in comparable bond strength (p > 0.05).

CONCLUSION

MBP at 50 mg/l is not recommended to condition dentin prior to RMGIC application. Moreover, ECL has a potential to be suggested for dentin conditioning compared to PAA.

Influence of fractional carbon-dioxide laser in comparison to ErCr-YSGG on the dentin bond integrity of bioactive materials

Objective:

The aim was to assess the influence of Er, Cr: YSGG laser (ECL) and fractional carbon dioxide laser (FCL) on the shear bond strength (SBS) and microleakage of bioactive restorative material to dentin.

Methods:

The study was performed in King Saud university in the month of June-July 2019. One hundred and twenty permanent teeth were vertically placed in acrylic resin. Based on the type of surface treatment regime (n=40), samples were divided into three groups. Group-I samples were surface conditioned with total etch and rinse (TE); Group-2 samples were surface treated with Er, Cr: YSGG laser (ECL) and Group-3 specimens were conditioned with fractional carbon dioxide laser (FCL). Surface treatment of dentin was followed by type of bulk fill resin (BFR) application. Tetric-N-Ceram was bonded to dentin conditioned with TE (n=20), FCL (n=20) and ECL (n=20). Similarly, bioactive material (BAM) was also bonded to conditioned surface (n=60). Samples (n=10) among each group were placed in a Universal testing machine. For microleakage testing 5 pairs of samples from each group (n=10) were placed in solution of 2% methylene blue for 24h Fracture analysis was performed using stereomicroscope at 40x magnification. Descriptive statistics i.e., means and standard for SBS and microleakage were compared using analysis of variance (ANOVA) and Tukey’s post hoc test at a significance level of (p < 0.05)

Results:

The highest SBS scores were displayed by TE-BFR (Bulk filled resin) (19.21 ± 0.925 Mpa) and the lowest shear bond scores were presented by FCL-BFR (11.06±1.611 Mpa). The lowest microleakage scores were exhibited by group ECL-BFR (24.11±13.01nm). Similarly, the highest microleakage score was displayed in group FCL-BAM (42.18±16.32 nm). Admixed failure was pertinent in groups conditioned by ECL. Moreover, groups conditioned with FCL adhesive type of failure was found in abundance.

Conclusions:

ECL has a potential to be used as an alternate to total etch and rinse for conditioning of dentin when bonded to bioactive materials.

Factors That Determine the Adhesive Strength in a Bioinspired Bone Tissue Adhesive

Phosphoserine-modified cements (PMCs) are a family of wet-field tissue adhesives that bond strongly to bone and biomaterials. The present study evaluated variations in the adhesive strength using a scatter plot, failure mode, and a regression analysis of eleven factors. All single-factor, continuous-variable correlations were poor (R2 < 0.25). The linear regression model explained 31.6% of variation in adhesive strength (R2 = 0.316 p < 0.001), with bond thickness predicting an 8.5% reduction in strength per 100 μm increase. Interestingly, PMC adhesive strength was insensitive to surface roughness (Sa 1.27–2.17 μm) and the unevenness (skew) of the adhesive bond (p > 0.167, 0.171, ANOVA). Bone glued in conditions mimicking the operating theatre (e.g., the rapid fixation and minimal fixation force in fluids) produced comparable adhesive strength in laboratory conditions (2.44 vs. 1.96 MPa, p > 0.986). The failure mode correlated strongly with the adhesive strength; low strength PMCs (<1 MPa) failed cohesively, while high strength (>2 MPa) PMCs failed adhesively. Failure occurred at the interface between the amorphous surface layer and the PMC bulk. PMC bonding is sufficient for clinical application, allowing for a wide tolerance in performance conditions while maintaining a minimal bond strength of 1.5–2 MPa to cortical bone and metal surfaces.

The effect of heat treatment and surface neutralization on bond strength of orthodontic brackets to lithium disilicate glass-ceramic

PURPOSE

The study evaluated and compared the effect of pre-etching heat treatment and post-etching surface neutralization on the surface texture parameters and initial adhesion strength of orthodontic brackets bonded to lithium disilicate glass-ceramic using water-based and resin-based cement.

MATERIALS AND METHODS

A total of 120 samples were fabricated by duplicating the buccal surface of the maxillary premolar. The samples were randomly assigned to two groups: the cementing surface of group 1 samples was heat-treated, and that of group 2 samples was left untreated. The samples of each group were further divided into 4 subgroups (n = 15) according to the use of neutralization and the type of cement used for bonding. The surface texture parameters after etching were determined using a non-contact surface profilometer, and the bond strength was determined by a universal material tester. The results were analyzed by analysis of variance and the Scheffe post hoc test.

RESULTS

The samples that were heat-treated showed statistically significant higher bond strength in all the subgroups, and the acid-neutralized samples showed higher bond strength using both types of cement; however, the increase was statistically significant only in resin-based cement-bonded samples. Resin-based cement-bonded samples showed higher bond strength than water-based cement-bonded samples.

CONCLUSION

Pre-etching heat treatment and post-etching acid neutralization of the cementing surface of lithium disilicate glass-ceramic significantly improve the surface texture and initial bond strength to orthodontic brackets.

Effect of Dentin Bonding Agents, Various Resin Composites and Curing Modes on Bond Strength to Human Dentin

This study investigated the influence of several dentin bonding agents, resin composites and curing modes on push-out bond strength to human dentin. 360 extracted caries-free third molars were prepared, cut into slices, embedded in epoxy resin and perforated centrally. One half of the specimens (180) were treated by using one-step adhesive systems and the other half (180) with multi-step adhesive systems. Subsequently, the cavities were filled with either universal, flowable or bulk-fill resin composite according to the manufactures’ product line and cured with either turbo or soft start program. After storage the push-out test was performed. The data was analyzed using Kolmogorov-Smirnov, three- and one-way ANOVA followed by the Scheffé post-hoc test, unpaired two-sample t-test (p < 0.05). The strongest influence on push-out bond strength was exerted by the resin composite type (partial eta squared η_P² = 0.505, p < 0.001), followed by the adhesive system (η_P² = 0.138, p < 0.001), while the choice of the curing intensity was not significant (p = 0.465). The effect of the binary or ternary combinations of the three parameters was significant for the combinations resin composite type coupled adhesive system (η_P² = 0.054, p < 0.001), only. The flowable resin composites showed predominantly mixed, while the universal and bulk-fill resin composite showed adhesive failure types. Cohesive failure types were not observed in any group. Multi-step adhesive systems are preferable to one-step adhesive systems due to their higher bond strength to dentin. Flowable resin composites showed the highest bond strength and should become more important as restoration material especially in cavity lining. The use of a soft start modus for polymerization of resin composites does not enhance the bond strength to dentin.

Adhesive bond integrity of dentin conditioned by photobiomodulation and bonded to bioactive restorative material

AIM

The aim of this in-vitro study is to investigate the shear bond strength (SBS) of Bioactive bulk fill restorative material (BARM) (Activa) by surface pre-treatment using Er,Cr:YSGG (ECL) on dentin in comparison to conventional dentin conditioning techniques.

MATERIAL AND METHODS

Sixty extracted non-carious, non-fractured, restoration free human molars were collected and mounted vertically in acrylic resin. The buccal surface of all molars were ground and polished with abrasive paper. The specimens were randomly allocated into four groups (n = 15) according to the type of surface treatment. Group 1 ECL + BARM, Group 2 ECL + Ketac + BARM, Group 3 Conventional Etch and Rinse + BARM, Group 4 Self-etch + BARM. The specimens from each group were positioned in a universal testing machine for SBS testing. Ten samples from each group were assessed for modes of failure. Means and standard deviations were compared using analysis of variance (ANOVA) and Tukey's post hoc test at a significance level of p < 0.05.

RESULTS

BARM bonded to dentin surface etched with conventional etch and rinse technique (group 3) exhibited SBS value of 18.45 ± 1.34. Similarly, the lowest bond strength was observed by group 4 (self-etch regime) bonded to BARM (16.09 ± 0.81). The bond strength among groups 1 (ECL + BARM), 2 (ECL + Ketac + BARM) and 3 (etch and rinse + BARM) were found to be comparable (p > 0.05).

CONCLUSION

Conditioning of dentin with photobiomodulation for the adhesive bonding of BARM showed comparable bond strength outcomes to conventional conditioning techniques.

Immediate enamel bond strength of universal adhesives to unground and ground surfaces in different etching modes

The purpose of this study was to determine the immediate bond effectiveness of universal adhesives to unground and ground enamel surfaces in different etching modes, through shear bond strength (SBS) tests and scanning electron microscopy observations. Three universal adhesives, a conventional two-step self-etch adhesive, and a conventional single-step self-etch adhesive were compared. Human enamel specimens from lower anterior teeth were divided into four groups and subjected to the following treatments: (i) unground enamel in self-etch mode; (ii) ground enamel in self-etch mode; (iii) unground enamel in etch-&-rinse mode; and (iv) ground enamel in etch-&-rinse mode. Bonded assemblies were subjected to SBS testing. All the adhesives showed significantly higher SBS values in etch-&-rinse mode than in self-etch mode, regardless of whether enamel was unground or ground. The influence of the enamel surface condition on SBS was different in different etching modes. Without pre-etching, all tested materials showed lower SBS values in unground enamel than in ground enamel. In etch-&-rinse mode, no significant differences in SBS values were observed between unground enamel and ground enamel for any of the adhesives tested. Phosphoric acid pre-etching before application of self-etch adhesives to an unground enamel surface is essential to enhance initial enamel bond effectiveness.

Effect of different combinations of surface treatment on adhesion of resin composite to zirconia

Purpose: The purpose of this laboratory study was to evaluate the effect of different surface treatment combinations on resin zirconia bonding. Materials and methods: One hundred and five pre-sintered zirconia quadrangles were prepared out of zirconia blocks, polished, then sintered and divided into five groups (n=21). Group I (control): samples were untreated, group II: grit-blasting with 50 µm alumina particles, group III: grit-blasting with 100 µm alumina particles, group IV: Er,Cr:YSGG laser, and group V: selective infiltration etching technique. Microstructural analysis was performed using scanning electron microscopy, atomic force microscopy, a diffractometer, and a profilometer. Cylinders of composite resin were luted with Panavia resin composite cementand Clearfil ceramic primer. Shear bond strength (SBS) was determined using a universal testing machine. Results: SBS results were analyzed using one-way ANOVA followed by Tukey post hoc tests for multiple comparisons. The level of significance was set to 0.05. SBS values of the studied groups II, III, IV, and V were 16.2±1.8 MPa, 15.7±3.7 MPa, 14.8±3.4 MPa, and 16.8±3.0 MPa, respectively. All values were significantly higher than the control group (10.48±1.80 MPa), but without a significant difference between them. Group III exhibited the roughest surface, and Group I had a more significantly reduced surface roughness value than any other group. Group III presented the highest significant increase of tetragonal to monoclinic phase transformation (13%). Conclusion: The use of grit-blasting with greater particles size enhanced SBS with resin composite cement, but induced a higher amount of monoclinic phase transformation. The use of primer based on adhesive monomer with the resin cement is required to enhance the bonding efficiency. The use of laser enhanced the surface roughness and the bonding ability to zirconia.

Is buffalo enamel a suitable substrate for bond strength tests?

Aim

The aim of this study was to compare the bonding strength of dental materials in buffalo (Bubalus bubalis var. kerebau), bovine, and human enamel and the susceptibility of these substrates in acid etching.

Materials and methods

A total of 20 human third molars, 20 bovine incisors, and 20 buffalo incisors were used in a mechanical assay of microshear. The substrates were demineralized via conditioning with 37% phosphoric acid, and the ultra-morphological pattern of each substrate was analyzed by scanning electron microscopy.

Results

The results showed that there was no significant difference in adhesive bonding strength values between buffalo and human enamel (P≥0.05), with a fracture pattern of mixed type for all experimental groups.

Conclusion

The results indicate that buffalo enamel is similar to human dental substrate in tests of adhesive bonding strength and also show a similar behavior in the acid conditioning of the enamel.