Shear Bond Strength Test Research Articles

Assessment of Shear Bond Strength to Sound and Artificial Caries Affected Dentin Using Different Adhesive Systems: An In Vitro Study

Introduction: We aimed to determine how the various adhesive systems affect the shear bond strength (SBS) to normal and artificially create caries affected dentin (CAD) in permanent teeth. Methods: Forty eight sound premolars had their occlusal enamel ground to create flattened midcoronal dentin. According to the dentin substrate, specimens were allocated into sound and artificially created CAD induction using the pH-cycling technique. Each group was further subdivided according to the adhesive materials: Scotchbond Universal Plus, Scotchbond Universal, and Adper Single Bond 2 adhesives (applied in Etch and Rinse Adhesive Protocol). After that, a composite was put on and shear bond strength (SBS) tests were done. Data analyzed using two-way ANOVA and chi-squared tests. Results: Overall model test of the ANOVA statistics showed that both type of dentin and types of adhesive had a significant effect on the SBS values (P < 0.001). Tuckey post hoc comparisons showed a significant difference for type of dentin (P < 0.001) and types of adhesive (P ≤ 0.005). Mode of failure assessment is non-statistically significant difference (P = 0.41). Conclusion: All adhesives showed a decrease in SBS when used on artificial CAD.

Exploration and preliminary clinical investigation of an adhesive approach for primary tooth restoration.

The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength (SBS) of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H 3PO 4. SBS and marginal microleakage tests were conducted with Single Bond Universal (SBU)/Single Bond 2 (SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H 3PO 4 pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H 3PO 4 etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12- and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12- and 18-month follow-up assessments. Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.

Effect of novel biomodification strategies on bonding to pulp chamber dentin - An In Vitro study.

Adhesion to dentin remains a tough challenge due to its heterogeneous composition, complex histologic structure and high tubular content, warranting the need to investigate methods to improve the bond strength of the commonly used access restorative materials to pulp chamber dentin. To evaluate the effect of dentin biomodification using 6.5% grape seed extract and a 980 nm diode LASER on the shear bond strength of resin-based bonded restoration to pulp chamber dentin. Access cavities were prepared in 42 extracted human maxillary premolars, which were then sectioned in a buccolingual direction. The samples were serially immersed in 5.25% NaOCl for 40 minutes and 17% EDTA for 3 minutes and allocated into three groups: the control group, the group pre-treated with 6.5% grape seed extract (GSE) and the group pre-treated with a 980 nm diode light amplification by stimulated emission of radiation (LASER). All the samples were restored with resin composites and subjected to shear bond strength testing using a universal testing machine. Statistical analysis was done using SPSS version 23 software. The mean shear bond strength was highest in the group pre-treated with GSE, followed by that pre-treated with diode LASER and finally in the control group. Dentin biomodification using both chemical and physical agents such as grape seed extract and diode LASER was shown to improve the shear bond strength of resin composite endodontic access restorations to the pulp chamber dentin.

Bonding of orthodontic ceramic brackets: Optimal conditioning method of lithium disilicate restorations

Introduction. According to the data obtained from the American Orthodontic Society survey conducted in 2015, the number of adult patients that requested orthodontic treatment increased from 14% to 27% between 2010 and 2014. Because of the increased age of the patients, fixed orthodontic treatment is expected to be performed on restored teeth, including all ceramic restorations. The objectives of the present study were to evaluate the influence of different surface treatments on the bond strength of ceramic brackets to lithium disilicate ceramic and to determine the mode of fracture. Material and method. 45 ceramic rectangular specimens were obtained from lithium disilicate CAD/CAM blocks which were divided in five groups according to the performed surface conditioning method: 1. grinding with a fine diamond bur (control group); 2. sandblasting with 29 ?m alumina (Al2O3); 3. etching with 4% hydrofluoric acid (HF); 4. sandblasting followed by conditioning with a universal primer - silanization (Al2O3 + S); 5. HF acid etching followed by silanization (HF + S). Shear bond strength test was performed after storing the samples in water bath for 7 days. All of the fractured samples were analyzed with optical microscope to determine the type of fracture. Results. HF acid etching followed by silanization performed the highest bond strength of 8.03 MPa, while sandblasting followed by silanization - 6.69 MPa. Mechanical surface conditioning with either HF acid etching or sandblasting resulted in significantly lower bond strength (2.65 MPa and 1.51 MPa respectively). Mainly adhesive mode of fractures was noticed after sandblasting and silanization, indicating minor chance of damaging the ceramic restoration after debonding, at the end of the orthodontic treatment, unlike the ceramic specimens in the Group 5 (HF + S) with 42.8% mixed and 14.4% cohesive fractures; 100% adhesive fractures were observed after mechanical treatments. Conclusion. According to the SBS test results and fracture type, sandblasting followed by the application of a universal primer can be considered as an adequate method for conditioning the lithium disilicate ceramic restorations before the bonding of ceramic orthodontic brackets.

Early and Delayed Effect of Cavity Disinfection with Chlorhexidine and Ozone on the Shear Bond Strength of Dentin to Glass Hybrid Restoration

Introduction: We aimed to evaluate the early and delayed effects of chlorhexidine (CHX) and ozone disinfection on the shear bond strength (SBS) of dentin to glass hybrid restoration. Methods: The occlusal surfaces of 60 extracted premolars were trimmed to obtain a flat dentinal surface and randomly divided into three groups, including distilled water (control), 2% CHX, and ozonized water. Each group was further subjected to a shear bond strength test after 24 hours and 3 months. Results: The overall model test (P &lt; 0.001), disinfectant and time (P &lt; 0.001), and time (P = 0.017) showed statistically significant differences among study groups. Yet, the type of disinfectant revealed a non-significant difference (P = 0.238). Post hoc tests showed SBS significantly decreasing over time in the control group (P &lt; 0.001) while the difference between 24 hours and 3 months for the CHX (P = 0.880) and ozone (P = 0.983) groups was not significant. Conclusion: Within the inherent limitations of in vitro studies, it can be concluded that cavity disinfection with CHX and ozone before glass hybrid restoration had a significant effect on the stability of SBS to dentin over 3 months. The type of disinfectant revealed non-significant difference.

Comparison of the shear bond strength of reconditioned metal brackets used in indirect bonding: an in vitro pilot study

Abstract Objectives: This study aimed to compare the shear bond strength (SBS) related to surface treatment methods of debonded brackets before indirect rebonding and to evaluate changes in SBS related to sandblasting time. Methods: After brackets were debonded from a dental cast during an indirect bonding procedure, seven groups were assigned to conduct SBS tests. Sandblasted groups were sprayed with Al2O3 for 3 s (Group II), 6 s (Group III), 9 s (Group IV), and 12 s (Group V). In Group VI, a no. 4 round low-speed bur was used to remove resin. In Group VII, the bracket base was coated with a plastic conditioner (Reliance, IL, USA) and Group I served as the control group. Results: The SBS of Group VII was not statistically different from that of the control group. The SBS of Group VI was not statistically different from that of Group II but higher than that of the control group (P &lt; 0.05). There was no statistical difference between Groups III, IV, and V, but was greater than the other groups (P &lt; 0.05). Conclusion: The group with surface treatment by sandblasting for more than 6 sec prior to indirect bonding recorded a higher SBS than the other groups. The SBS did not increase further even if the sandblasting time increased by more than 9 sec.

Effect of Different Surface Treatments and Application Times on Shear Bond Strength Between Polyetheretherketone and Composite Resin

Objective: To investigate the effect of various surface treatments and different application times on shear bond strength between polyetheretherketone and composite resin. Methods: A total of 110 disc-shaped polyetheretherketone specimens were randomly divided into 9 groups and 4 different surface treatments (control, sandblasting, tribochemical silica coating, sulfuric acid) were applied. The sandblasting, tribochemical silica coating, and sulfuric acid processes were performed 3 different times (10s, 15s, 20s). Then, the composite resins were applied to the treated surfaces of the polyetheretherketone specimens. The shear bond strength test and scanning electron microscopy analysis were performed. The data were statistically analyzed using analysis of variance and Duncan honest significant difference test. Results: One-way analysis of variance revealed differences in shear bond strength among the groups (p &lt;0.001). While the control group showed the lowest bond strength values (4.24 ± 1.53 MPa), 20 s of sulfuric acid process showed the highest bond strength values (27.91 ± 4.44 MPa). Conclusion: Depending on the application time to the material, additional surface treatments increase the polyetheretherketone composite bonding. Surface treatments with sulfuric acid applications provide higher surface bonding values than other treatments

Evaluation of the Bond Strength of Polyetherketoneketone to Dental Ceramic.

To evaluate the efficacy of different surface treatments on the bond strength of polyetherketoneketone (PEKK) to ceramic materials. PEKK test specimens were separated into four groups according to surface treatments (group S: sandblasting; group A: acid etching; group SA: sandblasting + acid etching; group C: control). Surface roughness values of PEKK specimens were measured before and after surface treatment. After the prepared PEKK specimens were bonded to lithium-disilicate glass-ceramic specimens with resin cement, they were kept in distilled water at 37°C for 24 h. Half of the specimens in each surface treatment group were thermocycled. All test specimens underwent shear bond strength testing. Failure modes were assessed using light microscopy and SEM. Statistical analysis demonstrated that surface treatments created significant roughness on the PEKK surfaces (p = 0.005). While group S showed the highest roughness values, group A showed the lowest. Of the thermocycled test groups, the sandblasting + acid etching group obtained the highest shear bond strengths. Among the non-thermocycled test groups, the sandblasting surface treatment group achieved the highest shear bond strengths. The application of surface treatments to enhance the bond strength of PEKK to ceramics has proven to be effective.

Influence of Cold Atmospheric Plasma on Surface Characteristics and Bond Strength of a Resin Nanoceramic.

The purpose of this study was to investigate the effect of cold atmospheric plasma (CAP) treatment on resin nanoceramic (RNC) surface state and its bond strength with resin cement. RNC with different surface treatments were prepared: control, sandblasting treatment (SB), hydrofluoric acid etching (HF) and plasma treatment of helium gas (CAP-He) and argon gas (CAP-Ar). The prepared samples were measured by SEM, Ra, Rz, contact angle goniometer, and XPS for surface characteristics. The shear bond test of RNC was examined in nine groups: SB + saline coupling agent (SL), HF + SL, CAP-He/Ar, CAP-He/Ar + SL, SB + CAP-He/Ar + SL, and control. The bond strength between RNC and resin cement was compared using shear bond strength test, before and after thermocycling. After CAP irradiation, the surface topography maintained, while the surface water contact angle was significantly reduced to 10.18° ± 1.36° (CAP-He) and 7.58° ± 1.79° (CAP-Ar). The removal of carbon contamination and inducing of oxygen radicals was detected after CAP treatment. The bond strength was improved by CAP treatment, but varied on CAP gas species and combination methods. CAP of Ar gas had better SBS than He gas. After thermocycling, CAP-Ar + SL showed the maximized shear bond strength (32.38 ± 1.42 MPa), even higher than SB + SL group (30.08 ± 2.80 MPa, p < 0.05). In conclusion, CAP treatment of helium and argon can improve the bonding properties of RNC by improving surface wettability, and CAP of argon gas combined with silane coupling agent shows the highest bond strength.

Shear Bond Strength of Two Self-Etching Adhesives to Air-Abraded Dentin: An in Vitro Study

Background: The aim of this research was to study the effect of air-abrasive treatment of dentin on the chemical composition of its surface and the adhesion strength of 2 self-etching adhesive systems (AS). Methods and Results: Powders based on aluminum oxide (Al2O3) (27µm) (KaVo, Biberach, Germany), sodium bicarbonate (NaHCO3) (40µm) (AIR-FlOW Classic Comfort, EMS, Nyon, Switzerland), and erythritol (14µm) (AIR-FLOW Plus, EMS, Nyon, Switzerland) were used for the air-abrasive treatment of adhesive surfaces. Bonding steps were carried out with Single Bond Universal (SBU) (3M ESPE, USA) and Bond Force 2 (BF2) (Toquyama, Japan). The adhesion strength of composite to dentin was evaluated on 80 samples prepared in accordance with the Ultradent Shear Bond Strength test. All samples were divided into 4 groups depending on the method of dentin surface processing. In the samples of Group 1 (n=20), aluminum oxide was used for the air-abrasive treatment of dentin. In Group 2 (n=20) and Group 3 (n=20), samples were treated using powders based on sodium bicarbonate and erythritol, respectively. Group 4 (control, n=20) included tooth samples in which the dentin surface was not air-abraded after preparation with carbide burs. Then, each group was divided into 2 subgroups (Sub-A and Sub-B) depending on the type of adhesive system used. Adhesive resin was applied and polymerized in accordance with the manufacturer’s instructions. Single Bond Universal (SBU) was used for the samples of Sub-A, and Bond Force 2 (BF2) (Toquyama, Japan) was used for the samples of Sub-B. Scanning electron microscopy and determining the surface elemental composition of samples were carried out on an SEM-EVO MA 10 (Carl Zeiss) and energy dispersive X-ray spectrometer with EDS Aztec Energy Advanced X-Act (Oxford Instruments). It was concluded that air-abrasive treatment of the dentin surface does not enhance the adhesion strength of composite material when using self-etch AS. Also, it was noted that the pH level of self-etch AS is not a crucial feature in determining the strength of the filling-tooth interface. The resulting variations in the elemental composition of dentin surface after air-abrasion with various mixtures and their effect on the efficacy of the different AS require further in vitro studies.

Effects of High-Intensity Light Curing Devices and Resin Adhesive System on Repair Strength of Amalgam with Resin Composite

This study aims to evaluate the effects of the new generation light curing devices and different adhesive systems on the shear repair strength between amalgam and resin composite. Ninety-six square-shaped amalgam (Cavex Non Gamma-2; Cavex Holland BV, Haarlem, the Netherlands) samples were prepared. The amalgam surfaces were polished with 600-grit abrasive paper. The prepared amalgam samples were divided into four groups (Single Bond Universal, 3M ESPE; Adper Easy One, 3M ESPE; Prebond SE, President Dental; OptiBond All-in-One, Kerr) according to the adhesive brand. Each adhesive group was divided into two subgroups according to the 3rd generation light curing devices (Elipar DeepCure-S [3M ESPE, USA], VALO Cordless [Ultradent, USA]) (n = 12). Microhybrid composite cylinders of 3 mm height and 2 mm diameter were placed on the amalgam surfaces by layered method with a silicone mold (Dynamic Plus; President Dental, Germany). Each layer was polymerized with a group specific light curing device. The samples were incubated in distilled water at 37 °C for 24 h before the shear-bond-strength test. The shear bond strength test was accomplished using a universal testing device. Statistical analyzes were made with two-way ANOVA and Tukey HSD tests. Two-way ANOVA revealed a significant effect of the adhesive system brand on bond strength (p &lt; 0.00). Prebound SE provided the lowest bond strength between both light curing devices groups. There was no significant difference between the two light-curing devices groups among Single Bond Universal, Adper Easy One and OptiBond All-in-One resin adhesive systems. It has been revealed that the high-intensity LED light curing device brand does not have a significant effect on the amalgam-resin composite repair strength, and the repair strength may be more affected by the brand of the adhesive system used.

Evaluation of ceramic adherence to cobalt-chromium alloys fabricated by different manufacturing techniques

Statement of problemSelective laser melting has been increasingly used in the fabrication of metal-ceramic prostheses. The longevity of the prostheses depends on the strength of the metal-ceramic bond, which may differ with the framework manufacturing technique. PurposeThe purpose of this in vitro study was to compare the bond strength of ceramic to cobalt-chromium (Co-Cr) alloys fabricated by different manufacturing methods. Material and methodsSixty Ø15×2-mm disk-shaped specimens were prepared and assigned to 3 groups (n=20) with different manufacturing methods: milled Co-Cr (M), selective laser melted Co-Cr (SLM), and cast Co-Cr (C). The disks were ceramic layered with a 2-mm thickness. Half of the specimens from each group were thermocycled. The shear bond strength (SBS) test was applied to all specimens. The microstructure changes after ceramic layering were evaluated by X-ray diffraction (XRD). The specimens’ surface morphology was analyzed by using scanning electron microscopy (SEM). ResultsThermocycling had a significant effect on SBS values in the SLM group (P=.017). Considering the registered Fmax (force inducing bonding failure), a significant difference was found between SLM and both M and C groups (P<.001). No significant difference was found between milled and cast Co-Cr (P=.885). The failure types were mostly mixed failures. Ceramic layering induced a crystallization increase in groups C and SLM. ConclusionsThe adhesion strength of ceramic to Co-Cr differed with alloy composition and manufacturing technique. The aging process influenced the results in the SLM group.

The effects of disinfection with Er, Cr:YSGG laser, application of CPP-ACP and sodium hypochlorite on shear bond strength.

The effects of commonly used antimicrobial and anticariogenic agents on the adhesion of pit and fissure sealants were investigated in this study. The aim of this study is to evaluate the effects of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr:YSGG) laser disinfection, casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) containing paste and sodium hypochlorite application before the placement of a resin-based pit and fissure sealant on the shear bond strength of primary tooth enamel. The shear bond strength test evaluated the bond strength of sealants on the buccal enamel surfaces of primary molar teeth. The study groups were pit and fissure sealant without any preapplication, pre application of disinfection with Er, Cr:YSGG laser, disinfection with Er, Cr:YSGG laser and CPP-ACP containing paste, sodium hypochlorite, sodium hypochlorite and CPP-ACP containing paste and CPP-ACP containing paste. The pit and fissure sealants were placed using 4 mm diameter, 2 mm height cylindrical plastic tubes. Shear force was applied to each sample. The surfaces of the broken samples were detected under stereomicroscope and were grouped as adhesive, cohesive, and mixed. The results of the study were evaluated using the SPSS 16.0 package program for statistical analysis. The groups where sodium hypochlorite and sodium hypochlorite with CPP-ACP were applied showed the lowest bond strength (p < 0.05). It was observed that most of the failures in these groups were adhesive-type failures. No significant difference was observed between the shear bond strengths of the other groups (p < 0.05). Er, Cr: YSGG laser and CPP-ACP containing paste are alternative methods for pre-application of fissure sealants.

Cyclic fatigue vs static loading for shear bond strength test of lithium disilicate and dentin substrates: A comparison of resin cement viscosities.

To explore the effect of resin cement viscosities on the shear bond strength under static and fatigue load of lithium disilicate and dentin substrates. Bonded tri-layer samples (lithium disilicate ceramic cylinder, resin cement, and substrate - ceramic or dentin) was performed considering 2 factors (n=15): "resin cement viscosity" (high, HV; or low, LV) and "loading mode" (static, s-SBS; or fatigue shear bond strength, f-SBS). The specimens were subjected to s-SBS (1mm/min, 1kN load cell) and f-SBS (cyclic fatigue, initial load: 10N; step-size: 5N; 10,000 cycles/step; underwater). Failure mode, topography, and finite element analysis (FEA) were performed. The resin cement viscosity did not influence the s-SBS and f-SBS of lithium disilicate substrate; however, it affected the bond strength to dentin, with HV presenting the worst fatigue behavior (f-SBS=6.89MPa). Cyclic loading in shear testing induced a notorious detrimental effect with a relevant decrease (16-56%) in bond strength and survival rates, except for dentin substrate and LV. Most failures were adhesive. A distinct pattern comparing the disilicate and dentin was identified and FEA demonstrated that there was a stress concentration on the top of the cement layer. Cyclic fatigue loading in shear testing has detrimental effects on the adhesive behavior and survival probabilities of bonded lithium disilicate sets, regardless of resin cement viscosity. In contrast, resin cement viscosity affects the bond strength and the survival rates of dentin substrate submitted to cyclic loading mode, in which a low viscosity results in better performance.

Evaluation and Comparison of Two Different Cleaning Procedures on Mechanical Properties for Recemented Restoration Using Two Conventional Glass Ionomer Cement Types: An In Vitro Study.

Background In modern dentistry, fixed dental prostheses are often the preferred and the most complex treatment procedures. However, the success of these procedures depends to a greatextent onthe durability and consistency of the ongoing reconstruction. This paper aimed to compare the shear bond characteristics of conventional glass ionomer cement types, namely, Vivaglass luting cement and GC fuji 1 cement, after being subjected to two different dentin-cleaning techniques: the tungsten carbide bur and the prophy jet. This would help determinewhether the castings that have been cleaned and recemented are just as tenacious as when they were initially placed. Methodology A total of 60 human teeth extracted due to periodontal disease were collected for this study. The teeth were cleaned and stored in a thymol arrangement after carefully removing any leftover fragile tissue. They were randomly grouped as follows: luted with Vivaglass cement (N = 30) in group A and GC fuji 1 cement (N = 30) in group B. Each group's debonded surfaces were arbitrarily split into three subgroups, with each containing 10 samples. This was done to comply with dentin-cleaning techniques for recementation. Results The intergroup bond strengths calculated were compared among the subgroups. The mean strength for subgroup IA was 2.78 ± 0.24 MPa, subgroup IB was 2.60 ± 0.30 MPa, subgroup IIA was 4.39 ± 0.19 MPa, subgroup IIB was 3.80 ± 0.23 MPa, subgroup III A was 4.52 ± 0.22 MPa, and subgroup IIIB was 3.63 ± 0.17 MPa. An analysis of variance test showed there was a significant difference between the subgroups (F = 117.60; P = 0.001). The results revealed that there was a significant difference between the subgroups. Shear bond strength testing was performed using common testing equipment. The results indicated that there was not any significant difference between the mean increases in the shear bond strength of the two luting cement types. However, the GC fuji 1 cement showed greater initial shear bond strength than the Vivaglass cement. Additionally, when the tungsten carbide bur was used as a cleaning techniquebefore recementing, itshowed greater shear bond strength compared to the prophy jet. Conclusions The initial shear bond strength of GC fuji1 (Group B) luting cement was slightly higher than that of Vivaglass (Group A), and the bond strength achieved after recementation with GC fuji 1 and surface cleaning with the carbide bur was the highest among the other three groups.

Influence of surface treatments on the bond strength of metal brackets to CAD/CAM materials and discoloration after various refinishing procedures : Scanning electron microscopy and atomic force microscopy study.

This study evaluated the shear bond strength (SBS) of ametal bracket bonded to three different computer-aided design/computer-aided manufacturing (CAD/CAM) restoration materials pretreated with different surface treatments. In addition, the surface topography and color change of the restorations after debonding with two different tungsten carbide burs were examined. A total of 216plates were cut from three different CAD/CAM blocks, each of which was divided into three subgroups with different pretreatment methods: (1)acid etching, (2)sandblasting, and (3)laser irradiation. Incisor metal brackets were bonded. The SBS test was performed, and the failure types were classified. Then, samples were randomly divided into two subgroups according to the adhesive removal procedure to be used: atungsten carbide bur with 12blades or 24blades (n = 12). Color change was calculated based on the ∆E00, and surface morphology was evaluated via SEM and AFM analysis. The SBS data revealed that the type of CAD/CAM material and the applied surface treatment significantly affected bond strength. The highest SBS values were detected for the Grandio Blocs (VOCO GmbH, Cuxhaven, Germany; 14.3 ± 4.4 MPa), and the lowest was observed for Cerasmart (GC Europe, Leuven, Belgium; 12.0 ± 4.0 MPa). The ∆E00 results demonstrated significant differences only as aresult of the applied surface treatment. The ∆E00 value in all groups was above the 1.77 threshold. CAD/CAM material types and surface treatments affected the bond strength, but the interactions of these factors did not. The chosen surface treatment also significantly affected the ∆E00 after the polishing was done.

Effect of Surface Treatments of Polyetherketoneketone as a Post Material on Shear Bond Strength to Root Dentin using Two Types of Resin Cement.

This study investigated the effects of mechanical and chemical pretreatment of polyetherketoneketone (PEKK) on shear bond strength (SBS) to root dentin using two types of resin cement. A total of 100 PEKK specimens were prepared and polished. Sixty specimens were mechanically treated by sandblasting (50-µm Al2O3 for 10 s at 0.2-0.25 MPa), and the remaining 40 were untreated. Self-adhesive resin cement and conventional resin cement were used. PEKK specimens bonded to root dentin using self-adhesive resin cement were classified into three groups by pretreatment method: (1) untreated PEKK, (2) mechanical pretreatment (sandblasted PEKK), and (3) both mechanical and chemical pretreatment (PEKK sandblasting as well as application of Scotchbond Universal; 3M Oral Care). Conventional resin cement was pretreated following the same steps (1-3) as those followed for self-adhesive specimens. Each group included 10 specimens. PEKK specimens after surface treatments were examined using SEM. SBS tests were performed using a universal testing machine, and data were statistically analyzed using one-way ANOVA and Tukey's multiple comparison test (p < 0.05). No significant difference was observed between cements with and without sandblasting. However, self-adhesive specimens with both mechanical and chemical pretreatments demonstrated higher SBS than other cements with or without pretreatment. Mechanical pretreatment by sandblasting did not improve the PEKK-root dentin SBS. However, combined mechanical (sandblasting) and chemical pretreatment (ScotchBond Universal) significantly improved the SBS between the PEKK and root dentin.

Bond strength to different CAD/CAM lithium disilicate reinforced ceramics.

To evaluate the microstructure and the influence of applying universal adhesive only versus universal adhesive with additional silane application on shear bond strength (SBS) to four different lithium disilicate ceramic (LDC) materials. Specimens (n=240, 1.5 mm thick) cut from four different CAD/CAM materials were polished and etched with 4.5% hydrofluoric (HF) acid according to manufacturers' instructions (20 s: IPS e.max CAD, n!ce; 30 s: Amber Mill, CEREC Tessera). For cementation, either universal adhesive only or silane + universal adhesive were applied before prefabricated composite cylinders were cemented using a dual-cure resin cement. SBS testing was performed either after 24 h or after 20,000 cycles thermocycling +2months water storage. Surfaces were analyzed with stereomicroscope for failure mode and with scanning-electron microscopy for microstructure of the LDC. Statistical analysis of the data was performed with non-parametric tests at α=0.001. SBS values for non-aged specimens ranged from 29.08 to 17.87 MPa and for aged specimens from 22.24 to 3.01 MPa. SBS was significantly reduced when silane was omitted after aging, (p < 0.001). Failure mode was mostly mixed with some cohesive failures in the LDC. Bond strengths are highly affected by the CAD/CAM LDC and their microstructures. The application of silane after hydrofluoric etching is still essential to obtain long-term bonding, irrespective of the presence of silane in the universal adhesive. Water degradation can significantly affect long-term bonding to novel LDC. When using a universal adhesive for bonding to LDC restorations, the best long-term bond is achieved if an additional application of silane precedes the universal adhesive.

Evaluation of Different Adhesive Resin Removal Methods after Debonding Ceramic Orthodontic Molar Tubes: A Scanning Electron Microscope Study.

To evaluate and compare the impacts, bond strength, residual adhesive, and time invested on the enamel surface after debonding of recently introduced ceramic buccal molar tubes with different systems. Ceramic molar tubes were bonded to fifty-four maxillary molar teeth, and a shear bond strength (SBS) test was performed. The adhesive remnant index (ARI) scores were recorded, and the samples were divided into two groups for adhesive removal with low-speed instruments: tungsten carbide bur or diamond-coated micropolisher point. The time to clean the enamel surfaces was also noted down for each tooth. The enamel surfaces were investigated with scanning electron microscope (SEM) after adhesives were cleaned. Shapiro-Wilk's, Kolmogorov-Smirnov's, and Student's independent t tests were used for statistical analysis. The mean SBS value of the tested ceramic molar tubes was 9.78 ± 1.85 MPa, and the majority of the samples were scored as ARI 1 and ARI 2. No statistically significant difference between PoGo micropolisher and TCB was found in terms of time values for surface cleaning. The enamel surface characteristics of TCB for adhesive remnant removal resulted in a better enamel surface than the single-step diamond polisher when the samples were investigated by using SEM. Ceramic molar tubes may be an enamel-safe product for patients seeking for fully aesthetic orthodontic treatment, if used in carefully handled clinical conditions. One-step polishing systems utilised with low-speed instruments could be used confidentially for cleaning the resin remnants on enamel after orthodontic treatment.

Comparative evaluation of shear bond strength of two different GICs in pediatric dentistry

Background: New restorative materials and techniques continue to appear in the market, the knowledge of which is required, to make an informed decision on the most suitable successful and cost effective treatment strategy. Aim: To compare and evaluate the Shear bond strength of different glass ionomer cements used in Pediatric dentistry. Materials and Methods: 60 Premolars were taken which were extracted due to orthodontic reasons. The extracted teeth were cleaned with a disinfectant and stored in distilled water at room temperature until further use. The teeth were divided into five groups: Group A: Anhydrous GIC, Group B: Giomer. All the samples were then subjected to shear bond strength test using universal testing machine. The data collected was tabulated and statistically analyzed using Anova one way test followed by tukey post Hoc HSD test using SPSS 16.0 software. Results: The Mean Shear bond strength was found to be maximum for Group B (Giomer) i.e. 2.90±0.55. Conclusion: Research and technology has revolutionized dental procedures. This revolution has occurred at such a rapid pace that it has become almost over whelming to the clinician who must take decision based on combination of experience and current trends.