Bond Strength Of Group Research Articles

The Use of Lasers in Enhancing the Bond Strength of Orthodontic Brackets

ABSTRACT Background: The use of lasers in orthodontics has garnered interest for its potential to enhance the bond strength between orthodontic brackets and tooth surfaces, a crucial factor for successful orthodontic treatment. This study aims to investigate the effect of laser irradiation on the bond strength of orthodontic brackets in a sample of 30 patients. Materials and Methods: Thirty patients undergoing orthodontic treatment were divided into two groups. In Group A, brackets were bonded using conventional methods, while in Group B, brackets were bonded after laser irradiation. A diode laser operating at 810 nm was used, with an energy setting of 2.5 W for 20 s. After bonding, a universal testing machine measured the bond strength in megapascals (MPa). The adhesive remnant index (ARI) was also recorded to determine the mode of bond failure. Statistical analyses were conducted to compare the results between the groups. Results: The mean bond strength in Group B (laser irradiation) was significantly higher (P < 0.05) than in Group A (conventional bonding). Group B exhibited a mean bond strength of 9.72 MPa, whereas Group A showed a mean bond strength of 7.41 MPa. The ARI scores indicated that Group B had more adhesive remaining on the tooth surface, suggesting a stronger bond. Conclusion: Laser irradiation prior to orthodontic bracket bonding resulted in significantly enhanced bond strength compared to conventional bonding methods. The increased bond strength and greater adhesive remnant on the tooth surface indicate that laser irradiation improves the adhesion between brackets and tooth enamel. Integrating lasers into orthodontic procedures has the potential to elevate treatment outcomes by ensuring durable bracket adhesion.

Dentin adhesion of bulk-fill composites and universal adhesives in class I-cavities with high C-factor

ObjectivesThe aim of this study was to compare the dentin adhesion of bulk-fill composites in high C-factor class I-cavities before and after thermocycling to a control group using incremental layering technique. MethodsA standardized class I-cavity was prepared into 195 human molars, then different universal adhesives were applied either in self-etch or etch & rinse mode, and the cavity was filled according to each materials application protocol. The material combinations used were a conventional layered composite as control, the respective bulk-fill product, two other bulk-fill composites made by different manufacturers, with one of them being tested using two different polymerization times. Furthermore, one thermoviscous bulk-fill composite and one self-adhesive restorative were examined of which the latter can only be applied in self-etch mode. In each group the dentin adhesion to the cavity bottom was measured using microtensile bond strength test initially (24 h water storage) and after thermocycling. All results were statistically analyzed using STATA 17.0. ResultsThe statistical analysis showed significant differences between the control and the experimental groups (p < 0.001). The highest mean bond strength before (14.8 ± 10.7 MPa) and after aging (14.2 ± 11.5 MPa) was measured for the etch & rinse-control group. Among the bulk-fill groups, the etch & rinse technique consistently showed higher bond strengths. Bond strength of groups with shortened polymerization did not exceed 2.1 MPa. The bond strength of the self-adhesive restoration material was low before and after thermocycling (2.7 MPa/ 0.0 MPa). Groups with low bond strength values showed a high number of pre-testing-failures. ConclusionsBulk-fill materials used in high C-factor class I-cavities showed lower bond strength during self-etch application. The same applies for a shortened polymerization regime, which cannot be recommended for high C-factor cavities. Clinical significanceToday, a large variety of materials and application techniques can be used when placing an adhesive restoration. Whether new instead of established procedures should be applied in high C-factor cavities has to be critically assessed, as they are a demanding scenario for adhesive restorations.

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

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). 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. 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. 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.

Bond strength of CAD/CAM denture teeth to a denture base resin in a milled monolithic unit.

Purpose Herein, the bond strength (BS) of denture teeth to a denture base resin in a milled monolithic unit was investigated and compared with those of 3D printed teeth to a 3D printed denture base and prefabricated teeth to a heat-cured acrylic resin before and after thermocycling.Methods Sixty specimens of a denture tooth attached to a cylindrical denture base were fabricated following ISO Standard 19736. Three fabrication techniques-3D printing, conventional compression molding, and milling using monolithic technology-were employed to mill teeth and denture base parts as a single unit. The BS was investigated before and after thermocycling. Data were statistically analyzed using the Kruskal-Wallis test with Bonferroni correction (α = 0.05).Results Before thermocycling, the mean BS of the milled group was significantly higher than that of the conventional group (P = 0.002). The 3D printed group showed no statistically significant difference from the milled (P = 0.051) and conventional (P = 0.824) groups. After thermocycling, although the mean BS values of the milled (P = 0.00) and 3D printed (P = 0.01) groups were significantly higher than that of the conventional group, there was no significant difference between them (P = 0.226). Only the BS of the conventional group was significantly reduced by thermocycling (P = 0.00).Conclusions The milled monolithic fabrication technique, which eliminates the need for a bonding step, offered a promising combination of high-precision digital fabrication and a significantly high BS. The BS of the conventional group significantly decreased after thermocycling.

Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

AimThis study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS.MethodsNinety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined.ResultsSBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05).ConclusionThe bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

Shear-bond strength of different Self-Etching adhesive systems to dentin with or without laser irradiation before photopolymerization (A comparative Study)

This study aimed at comparing shear-bond strength (SBS) of different self-etching adhesive systems (Clearfil S3 Bond Plus, G-Premio BOND and IBond) to dentin without or with diode-laser irradiation before photo-polymerization and to determine the effect of storage and thermo-cycling on SBS of adhesive systems. Methods: The buccal surface of 84 extracted maxillary premolars was grounded to create flat surface. The specimens were allocated into 3 groups (n = 28) depending upon the adhesive systems, then each group was divided into two sub-group (I, II) (n = 14). After the placement of respective adhesive systems on the flat surface, adhesive system in group I was photo-polymerized immediately, while in group II, the adhesive systems were exposed to diode-laser before photo-polymerization. Composite cylinder (4 mm in diameter and 2 mm height) was built on the flat surface of each specimen. Then group I and II were divided into two sub-groups (n = 7) according to the storage time and thermo-cycling (1 day without thermo-cycling or 72 days with thermo-cycling) then all the specimens were stored in distilled water. The SBS was measured at the end of storage period. ANOVA, Duncan’s Multiple Range Test and independent t-test “P ≤ 0.05” were used for data analysis. Results: G-premio BOND showed the highest mean value of SBS followed by Clearfil S3 Bond plus without significant difference between them, while IBond revealed the least mean value. Laser irradiation had positive effect on the bond-strength of all tested adhesive systems. The results also showed that the storage with thermo-cycling had negative effect on the bond-strength in groups without laser irradiation for all tested adhesive systems, while for groups with laser irradiation, the reduction in the bond-strength of all tested adhesive systems was not significant. Conclusion: Diode-laser application prior to photo-polymerization of self-etch adhesive systems significantly increased the bond-strength to dentin and can increase the durability of composite adhesion.

The Effect of Morpholine on Composite-to-Composite Repair Strength Contaminated with Saliva.

The aim of this study was to specifically explore the effects of morpholine on chemical surface treatments of aged resin composites contaminated with saliva to new resin composite repair strength. One hundred and thirty five resin composite specimens were fabricated and thermocycled to replicate an aged resin composite. These aged resin composites were randomly separated into nine groups (n = 15) depending on the various surface contaminants and surface treatment techniques. These groups were as follows: group 1-no surface treatment; group 2-no saliva + adhesive agent; group 3-no saliva + morpholine + adhesive agent; group 4-no saliva + morpholine; group 5-saliva; group 6-saliva + adhesive agent; group 7-saliva + morpholine + adhesive agent; group 8-saliva + morpholine; and group 9-saliva + phosphoric acid + adhesive agent. A mold was covered on the top of the specimen center and then filled with resin composite. The shear bond strengths and failure modes were examined. The collected data was analyzed using one-way ANOVA, and the significance level was determined using Tukey's test. Group 5 (3.31 ± 0.95 MPa) and group 6 (4.05 ± 0.93 MPa) showed the lowest bond strength statistically, while group 3 (23.66 ± 1.35 MPa) and group 7 (22.88 ± 1.96 MPa) showed the most significantly high bond strength. The bond strength in group 2 (16.41 ± 1.22 MPa) was significantly different from that in group 1 (9.83 ± 1.13 MPa), group 4 (10.71 ± 0.81 MPa), and group 8 (10.36 ± 1.53 MPa), while group 9's (17.31 ± 1.48 MPa) SBS was not significantly different. In conclusion, the application of morpholine on aged resin composite with or without contamination with saliva prior to the application of the adhesive agent increased the bond strength of aged resin composite repaired with new resin composite (p &lt; 0.05).

Shear bond strength of ceramic material veneered to zirconia core by layering and pressing techniques

Background: The advantages of the PFM systems are to combine the fracture resistance of the metal substructure with the aesthetic property of the porcelain. The present study compared the shear bond strength of ceramic material veneered to zirconia core by layering and pressing techniques.Materials and Methods: 50 samples of zirconia blocks were divided into 2 groups. Each group consisted of 25 samples. In group I, ceramic veneered over zirconia core by pressing technique and in group II, ceramic veneered over zirconia core by layering technique was used. The blocks were loaded up to failure which was assessed using universal testing machine.Results: The mean shear bond strength in group I was 13.4 MPa and in group II was 9.2 MPa. The difference found to be significant (P

Effect of green tea and sodium ascorbate on the shear bond strength of orthodontic brackets bonded on bleached enamel: An in-vitro study

ObjectiveThe primary objective was to assess and compare the shear bond strength of orthodontic brackets bonded on bleached enamel with and without using an anti-oxidizing agent.The secondary objective was to compare the shear bond strength of brackets between the groups with anti-oxidant application along with immediate bonding and that of delayed bonding without any anti-oxidant treatment, on bleached teeth. Materials & methods75 premolars were collected and thereafter randomly distributed into the 5 groups. Group 1 to 4 had undergone bleaching with 10% carbamide peroxide and group 5 was control. Group 1 was bonded immediately after bleaching while bonding was delayed in group 4 for a period of 1 week. Groups 2 and 3 received the anti-oxidant treatment with 10% sodium ascorbate gel and 10% green tea gel respectively. Hounsfield universal testing machine was used for testing the shear bond strength. ResultsFor group 1, the shear bond strength was significantly lower (mean 4.9 MPa) than group 5 (mean 12.5 MPa). The significant differences were observed on comparing the shear bond strength of antioxidant-treated and delayed bonding groups with control (p < 0.05). Mean shear bond strength in groups 2, 3 and 4 were 7.5 MPa, 9.6 MPa and 5.8 MPa respectively. ConclusionThe bond strength of brackets reduces immediately after the bleaching procedure. The bond strength can be reversed either by delaying the bonding for a period of 1 week or by using the anti-oxidizing agents but it is not up to the level of unbleached enamel.

English

BACKGROUND Endodontically treated teeth have higher fracture rate due to pronounced coronal destruction. The minimally invasive approach of associating adhesive techniques and posts seems to contribute to a better clinical prognosis for endodontically treated teeth. The purpose of this study was to evaluate the push out bond strength and mode of failure of fiber post using one self-etch resin cement and two selfadhesive resin cements. METHODS Sixty single rooted teeth were selected and decoronated 2 mm coronal to cementoenamel junction (CEJ). The teeth were prepared and obturated, then divided into three groups of 20 samples each. The post spaces were prepared and relyX fiber posts were cemented in group I with multilink N, in group II with relyX U200 and in group III with Maxcem elite luting cements. The specimens were sectioned into three slices of 2 ± 0.1 mm thickness to perform the push out test using universal testing machine. Failure modes were evaluated using scanning electron microscope. Thus, collected data was statistically analysed using one-way analysis of variance test. RESULTS The push out bond strength of group I was significantly higher than that of group II and group III (P &lt; 0.05). No statistically significant difference was found between group II and group III. There was significant difference between coronal, middle and apical thirds in each group. The mode of failures showed 78 % of the samples had adhesive failure while 22 % of the samples had mixed failure. CONCLUSIONS Multilink N was found to be significantly more effective than RelyX U200 and Maxcem elite. Most common type of failure observed was adhesive failure between dentine-cement interface. KEY WORDS Fiber Post, Self-Etch Cement, Self-Adhesive Cement, Bond Strength, Push Out Test

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

The aim of the present study was to evaluate the bond integrity of bioactive cement (BAc) 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 (BAc) 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. 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 BAc 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-BAc (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.

Influence of silver diamine fluoride compared to photodynamic therapy on the bond integrity of resin modified glass ionomer cement to demineralized dentin

To investigate the adhesive bond integrity of demineralized dentin (DD) treated with Silver Diamine Fluoride (SDF) and Photodynamic therapy (PDT) (SBS) bonded to resin modified glass ionomer cement (RMGIC). Sixty non-carious molars were mounted within the sections of polyvinyl pipes. Dentinal tubules were exposed, homogenized and polished. 10 samples were left untreated and categorized as group 1. Fifty samples were exposed to acetic acid for artificial demineralization and randomly allocated into 5 groups. Group 2- exposed to conditioner polyacrylic acid (PAA); group 3- samples were treated with 38 % SDF; group 4- samples protected by 3.8 % SDF; group 5- topical application of 38 % SDF along with and potassium iodide (KI) and group 6- DD was treated with PDT. All specimens were bonded to RMGIC, light cured and subjected to shear bond testing in a universal testing machine. Debonded surfaces were observed under optical microscopy at 40x magnification for failure modes. SBS was examined using analysis of variance (ANOVA) with Post-hoc test. For all test p-value less than 0.5 was considered statistically significant. Bond strength in group 5 specimens, (38 % SDF and KI - 15.91 ± 0.71 MPa) was significantly higher among all study groups (p < 0.05). The minimum SBS observed in group 1 samples, (mineralized dentin bonded to RMGIC- 7.44 ± 0.29 MPa) was significantly lower among tested treatment regimes. Samples in group 2 (DD conditioned with PAA and bonded to RMGIC) (11.39 ± 0.54 MPa), group 3 (DD treated with 38 % SDF) (12.42 ± 0.77 MPa) and group 6 (PDT treated DD) (11.52 ± 0.86 MPa) exhibited comparable outcomes (p > 0.05). Demineralized dentin (DD) treated with 38 % SDF and potassium iodide when bonded to RMGIC exhibited improved bond strength compared to other treatment regimes. Use of methylene blue photosensitizer for PDT, compromised adhesive integrity applied on DD.

Effect of Chlorhexidine on durability of two self-etch adhesive systems.

BackgroundDespite of the rapid development in the field of dental adhesives, the issue of reduction in dentin bond durability has still not been resolved. The activity of dentinal endogenous enzymes such as MMPs is one of the most important causes of failure in resin composite restorations. The aim of this study was to investigate the influence of Chlorhexidine on micro-tensile bond strength of two types of commercially available self-etch adhesives. Material and MethodsTwenty four sound and freshly extracted molars were selected. Four standardized flat mid-coronal dentinal disks were prepared from each tooth. The specimens were randomly assigned to 6 groups (n=16). Groups A(control group) and B were treated with Clearfill SE Bond based on the manufacturer’s instructions. Groups C and D were treated with 2% Chlorhexidine 60 seconds before applying Clearfill SE Bond. Groups E and F were treated with Peak Universal Bond according to the manufacturer’s instructions. All groups were stored in distilled water in room temperature. Microtensile bond strength in groups A, C, and E were tested 24 hours after preparation, while microtensile bond strength in groups B, D, and F were tested after 3 months storage and 3000 thermal cycles(5-55 °C). Statistical analysis was performed with SPSS 20 and µTBS test results were analyzed using the Two-way ANOVA test. ResultsµTBS was not significantly different between groups A, C, and E after 24 hours (P>0.5). There was no significant difference between groups B (Clearfill SE Bond + Aging) and D (Clearfill SE Bond + 2% CHX + Aging). The Peak Universal µTBS significantly decreased after the aging procedure (P<0.001). ConclusionsBased on the findings of this study, pretreatment with 2% CHX had no negative effect on the Clearfill SE Bond µTBS. However the µTBS of 0.2% CHX contained Peak Universal adhesive decreased significantly after aging. Key words:Self-etch adhesives, Micro-tensile bond strength, chlorhexidine, bond durability.

A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-Generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study.

ABSTRACTAimTo compare the shear bond strength of seventh- and eight-generation self-etch dentin bonding agents in primary teeth using universal testing machine.Materials and methodsForty extracted sound human primary molars were collected and randomly divided into two groups of 20 sample each. Shear bond strength of seventh-generation bonding agent [ADPER Single Bond Universal, (group II)] and eighth-generation bonding agent [Futurabond DC, VOCO Germany, (group I)] were calculated by using Universal Testing Machine (PTC/O83/ME, INSTRON, USA) and expressed in megapascals (MPa). Recorded data were compiled and subjected to statistical analysis using Student's t test.ResultsThe mean shear bond strength of group I (eighth-generation dentin bonding agent) and group II (seventh-generation dentin bonding agent) ranged from 22.10 to 37.10 MPa and 19.80 to 30.30 MPa, respectively Student's t test showed significantly different and higher (8.7%) shear bond strength in group I when compared to group II (p value = 0.017).ConclusionShear bond strength of eighth-generation dentin bonding agent (Futurabond DC) was better than seventh-generation dentin bonding agent (Adper Single Bond Universal).Clinical significanceAn effective bond to tooth would reduce marginal microleakage, bacterial penetration, postoperative sensitivity, possibility of pulpal inflammation, and preserve tooth structure by allowing minimal cavity preparation.How to cite this articleMishra A, Koul M, Upadhyay VK, et al. A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(3):225–229.

Kekuatan Perlekatan Geser Tumpatan Semen Ionomer Kaca pada Dentin setelah Aplikasi Dentin Conditioner dan Cavity Conditioner

Backround: Smear layer formed during cavity preparation interfere with the adhesion between restoration and tooth structure and is considered a barrier that would degrade the quality of adhesion. Smear layer does not have a stable substrate for adhesion, gradually layer dissolves in the restorative material and cause microleakage, penetration of bacteria and inflammation of the pulp. Adhesion to dentin is more difficult to achieve than enamel, therefore the cleaning procedure on dentin require special treatment. Conditioner form a weak acid is used to remove the smear layer and surface contamination on the email or dentin which can reduce the adhesion of the material and the tooth surface. Dentin conditioner is an acid material containing 10% polyacrylic acid conditioner while Cavity conditioner an acid material containing 20% polyacrylic acid and 3% aluminum chloride. The higher the concentration, the more smear layer is dissolved in order to obtain adhesion of glass ionomer cements better because it is not blocked by the smear layer. Purpose: The purpose of this laboratory research is to study the shear bond strength of glass ionomer cement in dentin after application dentin conditioner and cavity conditioner .Material and Method: Twenty seven bovine cow's teeth were divided into three groups. Each group consisted of nine samples. Group 1 was control (without conditioner). Group 2 was treated with the Dentin conditioner. Group 3 was treated with the Cavity conditioner. Result: The average shear bond strength in group 1 is 3.31 Mpa, group 2 is 7.74 MPa and group 3 is 9.92 Mpa. Conclusion: There is a significant difference between third group and the shear bond strength of glass ionomer cement on dentin with application of the Cavity conditioner is higher than with application of the Dentin conditioner and without application conditioner

Evaluation of modified micro-push-out bond strength of glass fiber posts with chemically treated resin cements

To evaluate the modified micro-push-out bond strengths of prefabricated glass fiber posts with silaneafter 35% phosphoric acid to resin cements. In the study, 40 glass fiber posts were randomly divided into 2 groups (20 posts in each group) for different surface treatments. Group 1, treated with silaneafter 35% phosphoric acid; group 2, no surface treatment (Control group). Then each group was randomly divided into 2 minor groups (modified group and traditional group), with each group with 10. So the four groups were group 1M (phosphoric acid + silane-modified), group 1T (phosphoric acid + silane-traditional), group 2M (control-modified), and group 2T (control-traditional). A modified micro-push-out bond strength test method was used in modified groups. In traditional groups, the 20 extracted human, single-rooted teeth were endodontically treated. Gutta-percha was removed with #1-2 Peeso Reamers (Mani), and the post space of each specimen was enlarged with a standard drill system from the corresponding fiber post system to create a 9 mm post space with at least 4 mm of filling material in the root apex. Following post cementation according to the manufacturer's instructions, the traditional micro-push-out bond strengths were tested using a universal testing machine(0.5 mm/min). Both failure modes were examined with a stereomicroscope. The data of the four groups were statistically analyzed using the one-way ANOVA test(α= 0.05). The bond strengths were (18.85±1.42) MPa for group 1M, (19.39±1.35) MPa for group 1T, (11.26±1.57) MPa for group 2M, and (11.27±1.83) MPa for group 2T. The bond strength of Group 1 was significantly higher than that of group 2(P<0.05), no matter which method was used. The fracture mode 100% in group M was the destruction of the post/resin interface, compared with 65.7% in group T. In contrasted to the traditional micro-push-out test, the modified test can evaluate the bond strength of fiber post to resin cement more effectively, and 35% phosphate acid + silane treatment can improve the bonding strength.

Comparison of shear bond strength of traditional 3-step composite with self etch primer and composite.

The revolution in orthodontics has been due to replacement of cemented bands by orthodontic brackets. Acid etching is required to bond a bracket on tooth’s surface. Traditional three step acid etch procedure consisted of etching, sealing/priming and bonding. The self etch system (etchant and primer together) can be used without the need for surface preparation, saving chair side time and minimizing contamination. Objectives: To compare the shear bond strength (SBS) of orthodontic bracket bonded with Conventional etching primer (Transbond XT, 3M Unitek) with self etch primer (Adper Prompt L-Pop, 3M ESPE). Study Design: Prospective study Setting: Orthodontic Clinic of Ihsan Mumtaz Hospital, Lahore and PCSIR (Lahore). Period: 6 months from June 2018 to December 2018. Material and Methods: 60 human maxillary premolars were randomly divided into 2 groups of 30 each. Group-I was bonded with conventional etching primer + composite and Group-II was bonded with self etch primer + composite. Shear bond strength was measured through Ionstron force testing machine. Statistical Analysis: For each variable, shear bond strength, arithmetic mean, standard deviation, minimum and maximum values were calculated. t-test was used to compare the shear bond strength (SBS) of the two groups and P value less than and equal to 0.05 was considered significant. Results: The mean shear bond strength in group 1 and group II was10.5MPa and 7.36MPa respectively. Conclusion: The shear bond strength of Conventional etching primer + adhesive was significantly higher than the shear bond strength of self etch primer +adhesive group.

Evaluation of shear bond strength of zirconia to composite resin using different adhesive systems.

BackgroundTo evaluate shear bond strength of zirconia to composite resin using different universal and conventional adhesives and a zirconia primer.Material and MethodsForty zirconia blocks were fabricated of zirconium ingots (10×10×5 mm) and sintered at 1530°C for 2 hours. They were then air-abraded with Al2O3 particles. The specimens were divided into 4 groups and subjected to one of the following bonding agents: Futurabond U (group 1), Clearfil Universal Bond, universal adhesives (group 2), Z-Prime Plus, zirconia primer (group 3) and Adper Single Bond 2, conventional adhesive (group 4). Composite resin was then applied in a diameter of 5 mm and in a thickness of 2 mm. All the specimens were stored in distilled water at 37°C for 24 hours and then thermocycled between 5°C and 55°C for 5000 cycles with a 30-second dwell time. The shear bond strength was then evaluated with a universal testing machine at a crosshead speed of 1 mm/min. Data (MPa) were analyzed using ANOVA and LSD test (P≤0.05). The specimens were evaluated under a stereomicroscope to determine the mode of failure.ResultsThe mean shear bond strength was 16,874 MPa in group I, 13.4434 MPa in group II, 11.6500 MPa in group III and 6.8700 MPa in group IV. ANOVA revealed that the shear bond strength in group IV was significantly lower than that in other groups (P≤0.05).ConclusionsThe shear bond strength in group I was significantly higher than that in groups III and IV. So Universal adhesives could provide higher shear bond strength of zirconia to composite resin after thermocycling compared to zirconia primers. Key words:10-MDP, shear bond strength, universal adhesive systems, zirconia primer.

Influence of the dentin smear layer trait on the bond strength of the self-adhesive resin cements

This work aimed to evaluate the influence of smear layer on the bonding effectiveness and durability of the self-adhesive resin cements to dentin. A total of 48 fresh caries-free third molars with exposed dentin surface were divided into two groups. The dentin surfaces were treated using a standard grit diamond bur (group A) or further polished using a fine grit diamond bur (group B) and then bonded with either of the two self-adhesive resin cements, namely, Clearfil SA Cement (CSA, Kuraray) and Multilink Speed (MS, Ivoclar Vivadent). After 24 h or 2-year water storage, a microtensile bond strength test was performed. In group A, the dentin surface was rough, the smear layer was thick, and the dentin tubule orifice detritus showed low embolism value. In group B, the dentin surface roughness decreased, the embolism proportion increased, and the smear layer became thin. The initial bonding strengths of CSA and MS in group A were significantly lower than those in group B (P<0.05). The bonding strengths of CSA and MS significantly decreased after two years of water storage (P<0.05). For CSA, the bond strength of group B was significantly lower than that of group A (P<0.05). For MS, the differences in the bonding strength between groups A and B were insignificant (P>0.05). The properties of the smear layer and the types of self-adhesive resin cement used affected the bond strength and durability.

The Micro-Shear Bond Strength of Various Resinous Restorative Materials to Aged Biodentine.

Introduction:The type of materials and application time of veneering restorations on calcium silicate cements are important factors which influence the interfacial properties. The aim of this study was to measure the micro-shear bond strength of a resin composite (RC) using several adhesive systems and a resin-modified glass ionomer cement (RM-GIC) to different aged Biodentine specimens. Methods and Materials:A total of 15 Biodentine blocks were prepared and assigned to three aging periods: 12 min, one week and one month. Then they were subdivided into five sub-groups to receive cylinders of resinous materials. RC was applied using different adhesive systems: A) no adhesive B) etch and rinse C) two-step self-etch and D) universal adhesive in self-etch mode and E) RM-GIC applied directly over Biodentine. Micro-shear bond strength was measured and the data were analyzed using one-way and two-way ANOVA. The level of significance was set at 0.05. Result:There was significant interaction between Biodentine aging periods and resinous materials (P<0.05). The highest value was obtained in group D bonded to the recently set Biodentine. Increasing the aging period to one week resulted in increased micro-shear bond strength in all groups expect for group D. One-month incubation time led to reduced shear bond strength in group A, C and D. Micro-shear bond strength values of group E increased to the longer aged Biodentine. Conclusion:Group D showed the highest bond strength to freshly mixed Biodentine.