Mean Bond Strength Research Articles

Comparative evaluation of the effect of nitrofurantoin and triple antibiotic paste on the push-out bond strength of epoxy resin sealer: An in vitro study

Abstract Context: Following chemomechanical preparation, the application of intracanal medicaments is recommended to further decrease the microbial count. To combat endodontic infections, the application of antibiotics as intracanal medicaments has been an option for years in endodontics. Aim: The aim of this study was to compare and evaluate the effect of antibiotic pastes on the push-out bond strength (POBS) of resin-based root canal sealer. Materials and Methods: Forty-eight extracted single-rooted teeth were used after decoronation to a standardized root length of 15 mm. Canals were enlarged up to size F3 using Protaper rotary instruments. Samples were randomly divided into three groups according to the intracanal medicament used. Group A: Nitrofurantoin (NIT) Paste, Group B: Triple antibiotic paste (TAP), and Group C: Control group (without intracanal dressing). After removal of the medicament (endoactivator), obturation was done with AH Plus sealer. Push-out bond strength was calculated using universal testing machine. Statistical Analysis: Data were analyzed using one-way ANOVA followed by post hoc Tukey and Kruskal–Wallis test (with a significance level of P < 0.05). Results: Compared to the control group, the POBS significantly increased after using intracanal medicaments with P < 0.05 (The results showed that the mean bond strength of TAP was highest, closely followed by NIT and least with the control group). Conclusion: Under the limitations of this study, it can be concluded that the use of TAP and NIT increases the POBS of the Epoxy Resin Sealer.

An in vitro study on comparative evaluation of shear bond strength of bioactive composite to tooth structure with various dentin conditioning agents

Bioactive materials are an alternative to conventional restorative materials, which have been promising and challenging at the present time. Etchants or bonding agents are not required as this bioactive material chemically binds to teeth. A potent resin hydroxyapatite complex is formed due to ionic interaction, further preventing microleakage. Applying citric acid and maleic acid is an added advantage in removing the formed smear layer during cavity preparation. This study uses various bonding and conditioning agents to evaluate the strength of bioactive composite shear bonds to the tooth structure. Sixty extracted human maxillary premolars were collected for this study. They were randomly divided into four groups. They were treated with their respective conditioning and bonding agents. The Statistical Package for Social Science software version 23 by IBM was used for data processing and analysis. All p-values less than 0.05 were considered statistically significant. The highest mean bond strength was recorded for the self-etch adhesive group (27.54 MPa), followed by the phosphoric acid group (23.77 MPa), maleic acid group (23.11 MPa), and control group (19.21 MPa). A comparison of intergroup mean bond strength was made using one-way ANOVA. 52.36 was the sum of squares between groups, and that within the group was 19.984, with a degree of freedom between groups being 3 and that within the group being 56, which was statistically significant. The post hoc Tukey test was used for individual group interaction, which was statistically significant. The bond strength of the Activa-restorative material was increased by the pre-conditioning tooth surface. G-bond self-etch adhesive showed the highest efficacy in improving the bond strength among other agents.

Effect of different surface treatments on shear bond strength of zirconia with various yttria contents

BackgroundAchieving a stable bond with zirconia requires mechanical and chemical bonding methods. Information regarding the optimal treatment method for zirconia with varying yttrium content is scarce. This study evaluated the effect of different surface treatments on the shear bond strength of zirconia with various yttria contents.Materials and methodsA total of 168 disc-shaped zirconia specimens were classified into 12 groups based on the surface treatment method, including airborne-particle abrasion (APA), selective infiltration etching (SIE), hot etching (HE), and control group with no treatment; and yttria contents including Zolid Zi (4.5–5.6 wt% yttrium), Zolid HT White (6.7–7.2 wt% yttrium), and Ceramill Zolid FX (9.15–9.55 wt% yttrium). The surface roughness (Ra and Rz) of the specimens and the shear bond strength was measured (α = 0.05).ResultsThe results indicated that the mean bond strength of all specimens was higher after different surface treatments compared to the control group, of which the APA method resulted in higher bonding strength in all kinds of zirconia than other methods (P < 0.05). In all types of zirconia, a significant difference was observed in surface roughness (Ra and Rz) resulting from various surface treatment methods (P < 0.001). Interaction of surface treatment methods and zirconia type significantly affected shear bond strength and surface roughness (P < 0.05).ConclusionAPA significantly enhanced shear bond strength and surface roughness across all zirconia types and yttria contents. The SIE and HE methods also showed promising results. Zolid Zi showed superior bond strength, whereas Zolid FX demonstrated reduced bond strength.

Microcomputed tomography assessment of microleakage and void formation under ceramic adhesive precoated orthodontic brackets

This study aimed to evaluate microleakage, voids, and gaps in ceramic adhesive precoated (APC) brackets using microcomputed tomography and investigate their correlation with bond strength. A total of 52 human premolars were included in this study. The teeth were randomly divided into 4groups of 13 teeth each. The brackets used in this study were the Clarity Advanced APC Flash-free Ceramic Bracket (3M Unitek, Monrovia, Calif) and the Clarity Advanced Ceramic Bracket (3M Unitek, Monrovia, Calif). The materials used for each group were as follows: (1) 37% phosphoric acid, Transbond XT primer (3M Unitek, Monrovia, Calif), and APC Flash-free Ceramic Bracket; (2) Transbond Plus self-etching primer and APC Flash-free Ceramic Bracket; (3) 37% phosphoric acid, Transbond XT primer, Transbond XT light-cure adhesive, and Clarity Advanced Ceramic Bracket; and (4) Transbond Plus self-etching primer, Transbond XT light-cure adhesive, and Clarity Advanced Ceramic Bracket. The teeth were scanned using microcomputed tomography for microleakage, void, and gap analyses. The bond strength was measured and recorded in megapascals. One-way analysis of variance was used to compare parameters with a normal distribution. The Kruskal-Wallis test was used to compare parameters that did not comply with the normal distribution. The relationships among variables were evaluated using Spearman and Pearson correlation coefficients. There were no statistically significant differences among the groups in terms of gap volume, void volume, and total void and gap volume values (P>0.05). No significant differences were observed in relation to bond strength (P>0.05). The mean bond strength was 20.42, 19.87, 19.28, and 19.47 for groups 1-4, respectively. The Spearman's correlation analysis results demonstrated that the bond strength was significantly affected by the gap volume and total void and gap volumes. The bond strength increased with reduced total volume of voids and gaps. There was no difference between the APC Flash-free Ceramic Bracket and the Clarity Advance Ceramic Bracket regarding bond strength, void volume, gap volume, and total void and gap volume. The gap volume and total void and gap volumes significantly affected the bond strength. The bond strength increased with decreased total void and gap volumes. The bond strengths of the APC Flash-free Ceramic Brackets were comparable to those of the ceramic brackets bonded using the conventional method.

Evaluation of the effect of aging on the shear bond strength between old composite resin restoration and the repair composite resin: an in-vitro study.

The current study aimed to evaluate the effect of aging on the repair bond strength between old composite resin and repaired composite resin and to evaluate which type of repair composite material provides better bond strength in different time durations. Eighty nano-hybrid composite specimens were randomly divided into four groups (N.=20) and exposed to accelerated aging from 0 to 2 years. Each group was further divided into two subgroups, A and B, repaired with packable and flowable composite respectively, after micro-abrasion treatment. Shear bond strength was assessed and statistically analyzed. It was observed that with an increase in aging time, the bond strength of both the composite materials used for repair decreased. The flowable composite's mean bond strength (22.09±0.65, 18.74±2.36, and 17.74±2.38 MPa) was more than the packable composite (21.97±0.84, 17.97±3.85, and 15.97±2.45 MPa) used for repair on aged specimens. In contrast, the bond strength of the packable was more than the flowable composite in control group specimens that were not aged (23.25±0.89 vs. 22.40±1.26). As restored composites age, their bond strength decreases. Flowable composite displays better repair shear strength than packable composite as aging progresses. Micro abrasion followed by flowable composite bonding can repair aged composite restorations effectively.

Shear bond strength evaluation of bioactive restorative materials on pretreated carious dentin-influence on silver diamine fluoride, potassium iodide, and glutathione.

Silver diamine fluoride (SDF) has gained popularity for its caries-arresting properties, yet its tendency to cause esthetic concerns due to black-staining limits its widespread acceptance. The aim of the study was to evaluate and compare the shear bond strength of Activa BioActive and Giomer restorative material with different protocols of SDF pretreatment on carious dentin. Ninety-two extracted teeth were decoronated at the cementoenamel junction, sectioned 1 mm into dentin, mounted in acrylic resin and randomly divided into four (n = 8) control and six (n = 10) experimental groups. Seventy-six samples underwent demineralization process for a period of 14 days for artificial carious dentin (ACD) formation. The samples categorized based on the dentin substrate (sound or ACD) were subjected to various SDF pretreatment protocols, i.e., only SDF, SDF with potassium iodide (KI), and SDF with glutathione (GSH). Further, bioactive restorative materials, i.e., Activa BioActive and Giomer (Beautifil II), were placed on it, and the samples were subjected to shear bond strength testing. Independent t-test was run to analyze the values obtained. Giomer exhibited better mean bond strength with SDF, SDF + KI, and SDF + GSH (6.56, 4.67, and 3.34 mega-pascals [MPa], respectively) compared to Activa BioActive (3.42, 3.27, and 2.96 MPa, respectively). This study contributes to understanding the interplay between SDF application protocols, esthetic concerns, and the adhesive properties of bioactive restorative materials. Giomer exhibited enhanced bond strength after SDF application, unlike Activa BioActive. In addition, incorporation of KI or GSH adversely affected the bond strength of both the restorative materials, underscoring the critical need for cautious clinical application. This study highlights the importance of selecting appropriate dentin pretreatment agents to maximize the bond strength of bioactive restorative materials with carious dentin. SDF application significantly enhanced the bond strength of Giomer with carious dentin compared to Activa BioActive, thus, making it a good choice for restoring nonesthetic areas. In addition, the application of KI or GSH to mitigate discoloration of carious dentin negatively affected the bond strength of both, Activa BioActive and Giomer. Thus, the clinicians should weigh the benefits of SDF against potential bond strength reductions when using KI or GSH, especially for esthetic restorations.

Evaluation of the Bond Strengths Between Dental Ceramics and Co-Cr Frameworks Made with Digital and Conventional Techniques.

Evaluate the influence of different Co-Cr framework manufacturing techniques on the bond strength between metal and two types of veneering ceramic with and without a metal primer. 72 metal specimens were fabricated using the same Co-Cr alloy (Keramit NP; Nobil Metal) with three different techniques: ingots for casting (Keramit NP); disks for CAD/CAM milling (Synergy Drive Keramit NP); and powder for SLM (Keramit NP-S). Each of the 24-specimen groups, was divided into two subgroups, according to the application, or not, of Nobil Metal Bonding (NMB) (Nobil Metal). Two different veneering ceramic systems were used: Ceramco iC (Dentsply) and Noritake super porcelain EX-3 (Noritake). The bond strength of the metal-ceramic system was evaluated using the three-point bending test and the modality of failure with SEM analysis. Three-way Anova with interactions was used to evaluate the influence of the metal production process, the presence or absence of the bonding agent and the type of veneering ceramic on ceramic-metal adhesion. All specimens exceeded the minimum bond strength of 25 MPa required by ISO Standard 9693 - 1:2012. The highest values of adhesion were registered for specimens manufactured with casted metal/Noritake veneering ceramic (40.59 ± 7.30 MPa). The lowest values were registered for specimens manufactured with CAD/CAM metal/NMB/Ceramco iC veneering ceramic (29.47 ± 3.38 MPa). The fabrication method and the type of veneering ceramic had a significant influence on the mean bond strength. The application of the NMB did not show an influence on bond strength.

Bond strength of polymer clay with room temperature vulcanizing maxillofacial silicone – An in vitro study

Aim: To assess and analyze the bond strength of polymeric organic clay and heat polymerized PMMA with RTV maxillofacial silicone with and without an adhesive primer. Settings and Design: The use of polymeric clay as a substructure for implant retained maxillofacial silicone prosthesis is suggested. However, the bond strength of polymeric clay with room temperature vulcanizing (RTV) maxillofacial silicone and heat polymerized polymethyl methacrylate(PMMA) with RTV maxillofacial silicone has yet to be studied. Materials and Methods: Fifty two samples were prepared in total. Group 1 (n = 13) silicone and PMMA without primer. Group 2 (n = 13) silicone and PMMA with primer. Group 3 (n = 13) silicone and polymer clay without primer. Group 4 (n = 13) silicone and polymer clay with primer. The samples were of dimensions of 75 mm × 10 mm × 3 mm. For groups 1 and 2, samples were fabricated with PMMA over which RTV silicone was manipulated, packed and vulcanized for 24 h. For Groups 3 and 4, polymer clay was molded to the required dimensions and hardened. RTV maxillofacial silicone was manipulated and packed over it and vulcanized. For Group 2 and 4 samples, primer was applied to the uncovered part of PMMA and polymeric clay respectively. The samples were subjected to a 180° and 90° (t peel test) peel strength test, respectively. Statistical Analysis Used: One way analysis of variance was used to analyze bond strength, which was then followed by a post hoc Tukey’s test. Results: The mean bond strength of silicone and PMMA without primer was 0.35 ± 0.07 mN/m, while silicone and PMMA with primer had a mean bond strength of 0.41 ± 0.04 mN/m. The mean bond strength of silicone and polymer clay without primer and silicone and polymer clay with primer was found to be 0.45 ± 0.13 mN/m and 0.30 ± 0.05 mN/m, respectively. An 80% research power and a 95% confidence interval were used in the statistical analysis. A significance threshold of P &lt; 0.05 was applied. Conclusion: The silicone to heat polymerized PMMA primer bond strength is the same as the silicone to polymer clay primer bond strength. Bond strength of polymer clay and maxillofacial silicone without primer is better than with primer. Therefore, without primer application, polymer clay substitutes PMMA as an interface between maxillofacial silicone material and attachments/keepers.

Effect of various root canal irrigants on bond strength with two obturating systems

Three-dimensional obturation and careful chemo-mechanical preparation of the root canal system are essential for successful endodontic therapy. The marginal adaption and bond strength of root canal sealers to dentin are critical for the effectiveness of various endodontic operations. Hence, bond strength of Thermo-plasticized Gutta-Percha/ AH Plus sealer and ActiV GP root canal obturation system was compared following EDTA, MTAD, CHX, and Distilled Water used as a final irrigation rinse. The sample consisted of forty extracted teeth which were divided into four groups based on the final irrigation rinse (i.e.,) Group A 3% NaOCl followed by saline and 17% EDTA irrigation as a final rinse, Group B - 3% NaOCl solution followed by saline and MTAD irrigation as a final rinse, Group C - 3% NaOCl solution followed by saline and 2% CHX irrigation as a final rinse, Group D - 3% NaOCl solution followed by saline and distilled water irrigation as a final rinse. Each group was further subdivided based on the obturation system as; thermo-plasticized Gutta-Percha and AH Plus sealer (subgroup 1), and ActiV GP obturation system (subgroup 2). Middle and coronal thirds of every root was cut horizontally with two milli-metres thickness. After that, each slice was examined under a stereomicroscope to measure the diameter of each obturation site and snap photos of each slice's was taken at two sides using a digital camera. Later, an Instron Universal Testing Machine was used to analyze the bond strength of each specimen. CHX- Thermo-plasticized Gutta-Percha /AH Plus (3.654 + 0.056MPa) yielded the maximum average bond strength value. The minimal mean bond strength was noted for distilled water/ActiVGP (1.313 + 0.014 MPa). The other subgroups yielded intermediate bond strength values. Statistically considerable variation was found between subgroup A1 EDTA- Thermo-plasticized Gutta-Percha /AH Plus and subgroup B1 MTAD- Thermo-plasticized Gutta-Percha/AH Plus respectively. It can be found that use of 2% CHX as a final rinse considerably increases the bond strength of both Thermo-plasticized Gutta-Percha/AH Plus and ActiV GP obturation systems.

Impact of different disinfection protocols on the bond strength of NeoMTA 2 bioceramic sealer used as a root canal apical plug (in vitro study)

IntroductionTreatment of an immature permanent tooth required a special disinfection protocol due to the presence of thin radicular walls, which are prone to fracture. Mineral Trioxide Aggregate (MTA) has been proposed as a root repair material for root canal treatment. The aim of this in vitro study was to compare the push-out bond strength of conventional White MTA cements and second generation NeoMTA 2 in imitated immature roots treated with different disinfection protocols, which are 5.25% sodium hypochlorite (NaOCl), followed by 17% ethylenediaminetetraacetic acid (EDTA), and NaOCl, followed by 20% etidronic acid (HEBP).MethodsThe root canals of freshly extracted single-root teeth were manually prepared until 90 K-file to imitate immature roots. Roots were randomly divided into four groups (G) according to the disinfection protocol (n = 15 per group). where G1 (NaOCl + EDTA + White MTA) and G2 (NaOCl + EDTA + NeoMTA 2) While G3 (NaOCl + HEBP + White MTA) and G4 (NaOCl + HEBP + NeoMTA 2) All groups were activated with manual agitation. All specimens were incubated for 48 h. The apical third of each root was perpendicularly sectioned to attain a slice of 3 mm thickness. Push-out bond strength values were assessed using a two-way ANOVA and a Student’s t test.ResultsG3 and G4 that were treated with HEPB showed higher significant push-out bond strength mean values than G1 and G2 treated with an EDTA chelating agent. Irrespective of the chelating agent used, it was found that both NeoMTA 2 and White MTA had no significant influence on push-out bond strength mean values (p ≤ 0.05).ConclusionThe combined use of 5.25% NaOCl and 20% HEBP increased the push-out strength values of both NeoMTA 2 and White MTA, rendering them suitable to be used as an alternative chelating agent to EDTA.

Long-Term Bonding Efficacy of CAD/CAM Hybrid Restorative Materials and Universal Adhesives.

In-office and lab milled prostheses are the staple for indirect restorations. It is therefore critical to determine their long-term bonding durability. CAD/ CAM blocks of two classes of restorative materials: 1) a nano-ceramic reinforced polymer matrix (NCPM) and, 2) a polymer-infiltrated ceramic network (PICN) were bonded using four different universal adhesives (UA) and silane systems. A lithium disilicate glassceramic (LDS) was used as a reference. The blocks were bisected and bonded with different UA/resin-cement pairs. Bonded blocks were then cut into 1.0x1.0x12.0 mm bar specimens for microtensile bond testing. Half the bars were subjected to bond strength testing immediately and the other half after aging by 50,000 thermal cycles between 5°C and 55°C. ANOVA and post-hoc tests were used to compare mean bond strength among groups. NCPM presented consistently high bond strength regardless of bonding techniques, while the bond strength of PICN and LDS were lower when bonded with UA relative to traditional silanes. The more hydrophilic UA produced higher bond strengths. Glass-ceramics exhibited lower bond strength with UA than the conventional etch-rinse-silane techniques. However, UAs preserved bonding interface in the long-term. NCPM displayed superior bond strength relative to PICN and LDS regardless of the type of adhesives and bonding techniques.

Repair Bond Strength of Composite Resin to Dental Ceramic Using Various Surface Treatments: An In Vitro Study.

This research aims to evaluate and compare the effect of various surface treatments and adhesive types on the bond strength between composite resin and two types of ceramic materials. A total of 98 disk-shaped of 10 mm diameter and 4 mm thickness were fabricated for each of the zirconia (H. C. Starck) and lithium disilicate (IPS E-Max computer-aided design), which were implanted individually in the acrylic resin mold leaving one surface exposed. The disks in each group were sub-divided according to the surface treatments into seven groups (n = 14): [hydrofluoric acid (HF, 9.5%), air abrasion, bur, laser, HF + bur, HF + air abrasion, HF + laser]. Each sub-group was further divided into two groups (n = 7) according to the type of adhesive used for the repairing procedure [G-Premio Bond universal adhesive group and intraoral repair kit (BISCO) group]. Each adhesive was applied depending on manufacturer instructions and, then, the composite cylinder (4 mm in diameter and 4 mm in height) was built on the pre-determined treated ceramic surface area by the addition of rubber mold. Then the samples were stored in distal water for 24 h. After that, all groups were submitted to a shear bond test using an Instron testing machine (TSTM 02500; Elista Ltd., Istanbul, Turkey) at 0.5 mm/min a crosshead speed. The data were analyzed by three-way analysis of variance and Tukey post hoc test at (P ≤ 0.05). The HF + air abrasion groups registered the higher bond strength but with no statistically significant difference from groups of HF + bur. While the laser groups showed the lowest mean bond strength. Generally, E-Max registered significantly higher bond strength in comparison to zirconia. Finally, the BISCO repair system registered a significantly higher bond strength value in comparison to G-Premio. Combined surface treatment of HF + air abrasion with an intraoral repair kit can provide a promising method for repairing cracked ceramic restorations. However, repairing lithium disilicate is more predictable and successful than zirconia.

Comparison of various methods of restoring adhesion to recently bleached enamel

AimThis study compared the effectiveness of several techniques in restoring compromised bonding to recently bleached enamel.MethodsSeventy-five healthy bovine incisors were divided into five groups (n = 15). Fifteen teeth (Group 1) remained intact, whereas 60 (Groups 2 to 5) underwent at-home bleaching with 16% carbamide peroxide. The bonding procedures were as follows: Group 1: Bonding of resin composite to unbleached enamel; Group 2: Bonding immediately after bleaching; Group 3: Application of a 10% sodium ascorbate solution for 10 min before bonding; Group 4: Enamel removal to the depth of 0.5 mm; and Group 5: Increased curing time of the bonding agent to 80 instead of 20 s. After 24 h, the specimens were subjected to micro-shear testing, and the failure mode was determined.ResultsANOVA revealed a significant difference in bond strength among the groups (P < 0.001). The mean bond strength was significantly lower in group 2 than in other groups (P < 0.05), which showed comparable bond strength to each other (P > 0.05). Adhesive failure was the most predominant failure type in all groups. The mixed failure occurred with a frequency of 26.7% in groups 3 and 5. The Fisher’s exact test revealed a significant difference in failure modes among the groups (P = 0.047).ConclusionsThe three experimental procedures used in this study, including the application of 10% sodium ascorbate before bonding, enamel removal to the depth of 0.5 mm, and increasing the curing time of the bonding agent to 80 s, were effective in restoring the compromised bonding to recently bleached enamel.

Effects of Artificial Aging of Direct Resin Nano-Hybrid Composite on Mean Bond Strength Values for Veneer Ceramic Samples.

BACKGROUND This study investigates the effect of artificial aging of direct resin nanohybrid composites on mean bond strength values for veneer ceramic samples. MATERIAL AND METHODS Ninety direct nanohybrid composite resin (Tetric N-Ceram) cylindrical discs were divided into 5 groups (n=18 each) based on aging cycles (thermocycling), as follows: TC=no aging (control), T1=850, T3=2500, T6=5000, and T12=10000 cycles, representing 1, 3, 6, and 12 months of clinical usage, respectively. Lithium disilicate glass ceramic (IPS e.max Press) cylindrical discs were cemented to resin discs using resin cement (Variolink N) after surface treatments (ceramic etching, silaning, composite abrasion). Differences in means between subgroups were calculated using one-way ANOVA, followed by the Tukey honestly significant differences post hoc test. Differences were considered statistically significant with a P value ≤0.05. RESULTS The highest SBS between ceramic and aged composite was observed at 1 month (m=20.35) but did not differ significantly from the control group (m=20.97). For all other subgroups (3, 6, 12 months) SBS was significantly less than that of the control (P≤0.05). At 1 and 3 months, cohesive failures were more common, whereas adhesive failures were more common in 6- and 12-month-old composites. CONCLUSIONS SBS of aged composites was less than that of non-aged composites, with SBS decreasing proportionally as the resin aged. When cementing a ceramic restoration over existing composite restorations, those older than 1 month should be removed and replaced with new ones.

Effect of Er:YAG laser surface treatment on surface properties and shear-bond strength of resin-cement to three translucent zirconia: an in-vitro study

Achieving optimal bonding to translucent zirconia poses certain challenges as there is no consensus on ideal surface treatment method. Therefore, the aim of present investigation is to evaluate effect of Er:YAG laser treatment on wettability, surface roughness and shear-bond strength of three Yttrium oxide-stabilized zirconium-oxide polycrystal translucent zirconias. 120 specimens (n = 40/zirconia type) were prepared from three commercially-available translucent zirconias (Dentsply Sirona, USA); Translucent, High-Translucent and Ultra-Translucent zirconia. Specimens were sub-divided (n = 20/surface-treatment) into control and Er:YAG laser surface-treated groups. Regarding water wettability test; goniometer was used to measure contact angle before and after laser treatment. Surface roughness was measured using atomic force microscope. For shear-bond strength (SBS) test; the control group was sandblasted. All resin-bonded zirconia specimens were thermocycled for 5000 cycle and subjected to shear force using universal testing machine with 0.5 mm/min crosshead-speed. Results were statistically analyzed using two-way-analysis-of- variance (p ≤ 0.05). There was significant decrease in average contact angles (p-value < 0.001) in all zirconia groups after laser treatment. For roughness test; insignificant difference in average Ra in Translucent zirconia group. However, significant increase in mean Ra was revealed after laser treatment for High and Ultra-Translucent zirconias. For SBS test, results revealed insignificant difference in average bond strength after laser treatment in Translucent and High-translucent zirconia groups. Significant increase in mean bond strength of Ultra-Translucent zirconia was recorded. Er: YAG laser treatment significantly affected surface properties and shear-bond strength of Ultra-Translucent zirconia. Er:YAG laser irradiation may be a promising zirconia surface treatment method.Graphical

Sex-specific social aging in wild African lions

There is a growing interest in social behavior change with age,1,2,3,4,5 and the impacts of sociality on longevity,6,7,8 but current knowledge is broadly limited to primates, societies structured by dominance hierarchies, or single-sex studies. It is less clear how social aging patterns emerge in carnivores. The African lion (Panthera leo), a species that lives in egalitarian fission-fusion societies, presents an exceptional opportunity to examine social aging. Across felids, lions are unique in their dependence on conspecifics for many essential processes,9,10,11 and there is vast knowledge of lion behavioral ecology,10,11,12,13,14 including documented reproductive senescence in both sexes.14,15 Applying spatial-social network analyses across 30 years of data on the wild Serengeti lion population, we show that sex strongly modulates patterns of social aging and longevity. Group size increased with age for both sexes, but only males experienced significant changes in associate numbers (degree), specifically to females, which peaked in mid-life before declining. While aging females experienced declines in intra-sex connectivity (strength) and bond strength (mean strength), they peaked in both to males during mid-life. Male inter-sex strength also peaked in mid-life, while conversely their intra-sex strength and mean strength significantly dipped in mid-life. Although social associations were important for survival in both sexes, the investment diverged significantly: females' overall network connectivity was key for longevity, while the number of associates was important for males. These findings illustrate important potential effects of social aging in a wild carnivore and demonstrate how these diverge strongly between the sexes.

The effect of surface conditioning techniques on the shear bond strength of zirconia-reinforced lithium silicate ceramic following adhesive cementation – An in vitro study

Aim: The aim of this study was to determine the effect of different surface conditioning techniques on the bond strength between zirconia-reinforced lithium silicate (ZLS) ceramics and resin cement. Materials and Methods: Fifty samples of ZLS ceramic were used and allotted into five groups with 10 samples per group based on the type of surface conditioning technique. The ceramic specimens were crystallized and embedded into acrylic resin. The five groups were group 1 (negative control–without surface treatment); group 2 (10% hydrofluoric [HF] acid + silanization); group 3 (10% HF acid only); group 4 (self-etching ceramic primer [SECP]); and group 5 (experimental laboratory sealing of the conditioned surface). Resin cylinders were bonded using self-adhesive resin cement and were subjected to thermocycling after 24 h storage. The shear bond strength was tested with a universal testing machine. Statistical Analysis Used: One-way ANOVA was used for comparing five groups (P &lt; 0.05 was considered significant). Results: Group 4 showed the highest mean bond strength value (23.4 MPa ± 2.21 MPa). A statistically significant difference was noted between group 4 and all the other groups tested in the study (P &lt; 0.05). Conclusion: It can be concluded that the SECP can be considered an alternative to the conventional protocol of HF acid and silane application for the surface conditioning of ZLS ceramic.

Effectiveness of Different Bonding Agents in Minimally Invasive Cavity Preparations

ABSTRACT Objective: This research is meant to evaluate the effectiveness of different bonding agents in minimally invasive cavity preparations at a tertiary care center. Materials and Methods: A prospective research was conducted involving patients requiring minimally invasive cavity preparations. Patients were randomly assigned to groups based on the bonding agent used. Standardized cavity preparations were performed, and bonding agent application followed manufacturer instructions. Outcome measures included bond strength and marginal adaptation. Data were analyzed using appropriate statistical methods. Results: Bonding Agent A exhibited the highest mean bond strength (25.6 MPa) and superior marginal adaptation (mean score: 4.2) compared to Bonding Agents B and C. These differences were statistically significant (P &lt; 0.001 for bond strength, P &lt; 0.05 for marginal adaptation). Conclusion: Bonding Agent A demonstrated superior performance in achieving durable and esthetically pleasing restorations in minimally invasive cavity preparations. These findings underscore the importance of selecting appropriate bonding agents for conservative dental treatments to optimize treatment outcomes and patient satisfaction.

Nanostructured ZnO thin film to enhance gutta-percha’s adhesion to endodontic sealers

BackgroundGutta-percha (GP) combined with an endodontic sealer is still the core material most widely used for tridimensional obturation. The sealer acts as a bonding agent between the GP and the root dentinal walls. However, one of the main drawbacks of GP core material is the lack of adhesiveness to the sealer. ZnO thin films have many remarkable features due to their considerable bond strength, good optical quality, and excellent piezoelectric, antibacterial, and antifungal properties, offering many potential applications in various fields. This study aimed to explore the influence of GP surface’s functionalization with a nanostructured ZnO thin film on its adhesiveness to endodontic sealers.MethodsConventional GP samples were divided randomly into three groups: (a) Untreated GP (control); (b) GP treated with argon plasma (PT); (c) Functionalized GP (PT followed by ZnO thin film deposition). GP’s surface functionalization encompassed a multi-step process. First, a low-pressure argon PT was applied to modify the GP surface, followed by a ZnO thin film deposition via magnetron sputtering. The surface morphology was assessed using SEM and water contact angle analysis. Further comprehensive testing included tensile bond strength assessment evaluating Endoresin and AH Plus Bioceramic sealers’ adhesion to GP. ANOVA procedures were used for data statistical analysis.ResultsThe ZnO thin film reproduced the underlying surface topography produced by PT. ZnO thin film deposition decreased the water contact angle compared to the control (p < 0.001). Endoresin showed a statistically higher mean bond strength value than AH Plus Bioceramic (p < 0.001). There was a statistically significant difference between the control and the ZnO-functionalized GP (p = 0.006), with the latter presenting the highest mean bond strength value.ConclusionsThe deposition of a nanostructured ZnO thin film on GP surface induced a shift towards hydrophilicity and an increased GP’s adhesion to Endoresin and AH Bioceramic sealers.

Effects of Internal Bleaching on Microtensile Bond Strength of a Former Veneer Composite to Tooth Enamel

Background: At present, combined provision of direct composite restorations and dental bleaching has become increasingly popular to meet the esthetic demands of patients. This study aimed to assess the effect of internal bleaching on microtensile bond strength of composite to freshly veneered enamel. Methods: In this in vitro experimental study, 50 sound extracted human premolars were randomly divided into five groups (n=10). All teeth received composite veneers. Two groups underwent no further intervention and were subjected to measurement of microtensile bond strength of composite to enamel 24 hr and one week after the veneering. The remaining three groups underwent internal bleaching. Group 3 underwent bleaching one month after the veneering, and microtensile bond strength was measured after 24 hr. In groups 4 and 5, bleaching was performed immediately after the veneering. Microtensile bond strength was measured after 24 hr in group 4 and after one month in group 5. Data were analyzed using one-way ANOVA. Results: All the groups were not significantly different regarding the mean bond strength (p=0.110), but they were significantly different in terms of the mode of failure (p=0.01) such that the mode of failure was mainly adhesive in the three bleached groups. Conclusion: Internal bleaching after composite veneering has no significant effect on microtensile bond strength of composite to the enamel.