Bond strength and surface roughness assessment of novel antimicrobial polymeric coated dental cement.

Resin cement integrated with zein-incorporated magnesium oxide nanoparticles has previously been found to inhibit oral microbes and decrease bacterial biofilm. However, the bond strength and surface features of this biomaterial have yet to be investigated. The objective of this study was to evaluate the shear bond strength, mode of fracture, and surface roughness of resin cement modified with zein-incorporated magnesium oxide nanoparticles. Characterization of the cement was performed by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. 126 human teeth were divided into 3 groups and cemented to lithium disilicate ceramic using resin cement with zein-incorporated magnesium oxide nanoparticles at concentrations of 0%, 1%, and 2% (n = 42). 21 samples of each group were subjected to the shear bond strength test, while the other 21 underwent thermocycling for 10,000 cycles before the test, after which all samples were evaluated for the mode of fracture. To assess surface roughness, resin cement disks were analyzed by a profilometer before and after undergoing thermocycling for 10,000 cycles. The shear bond strength of the cement with 1% and 2% nanoparticles was significantly higher than the control before thermocycling. The mode of fracture was found to be mainly adhesive with all groups, with the unmodified cement presenting the highest cohesive failure. There was no significant difference in surface roughness between the groups before or after thermocycling. The addition of zein-incorporated magnesium oxide nanoparticles to resin cement improved or maintained the shear bond strength and surface roughness of the resin cement.

Suitability of Direct Resin Composites in Restoring Endodontically Treated Teeth (ETT).

(1) Background: The in vitro study aimed to investigate mechanical characteristics of resin composites and their suitability in direct restauration of endodontically treated teeth (ETT). (2) Methods: 38 endodontically treated premolars with occlusal access cavities were directly restored using the following resin composites and adhesives: Tetric Evo Ceram® + Syntac classic® (n = 10), Venus Diamond® + iBond Total-Etch® (n = 10), Grandio® + Solobond M® (n = 9), Estelite® Sigma Quick + Bond Force® (n = 9). After thermocycling, the elastic modulus, shear-bond-strength, fracture load (Fmax) and fracture mode distribution were evaluated. Statistical analysis: one-way ANOVA, t-test, Kruskal-Wallis test; p < 0.05. (3) Results: Grandio® showed the highest E-modulus (15,857.9 MPa) which was significant to Venus Diamond® (13,058.83 MPa), Tetric Evo Ceram® (8636.0 MPa) and Estelite® Sigma Quick (7004.58 MPa). The highest shear-bond-strength was observed for Solobond M® (17.28 MPa), followed by iBond® (16.61 MPa), Syntac classic® (16.41 MPa) and Bond Force® (8.37 MPa, p < 0.05). The highest fracture load (Fmax) was estimated for ETT restored with Venus Diamond® (1106.83 N), followed by Estelite® Sigma Quick (1030.1 N), Tetric Evo Ceram® (1029 N) and Grandio® (921 N). Fracture-mode distribution did not show any significant differences. (4) Conclusions: The observed resin composites and adhesives show reliable mechanical characteristics and seem to be suitable for direct restoration of endodontically treated teeth.

Effects of Er,Cr:YSGG Laser Surface Treatments and Composites with Different Viscosities on the Repair Bond Strength of CAD/CAM Resin Nanoceramic.

This study aims to evaluate the repair micro-shear bond strength of the CAD/CAM resin nanoceramic block treated using four different surface treatments and composite resins of different viscosities. For the current study, 96 samples with dimensions of 14 × 12 × 2 mm were obtained from a CAD/CAM resin nanoceramic block (Cerasmart) with a low-speed precision cutting saw under water cooling. The relevant samples were randomly divided into four groups according to the surface treatment processes: grinding with diamond bur, aluminum oxide airborne-particle abrasion, long-pulse laser, and short-pulse laser. Following silane application, universal adhesive was applied to all surface-treated samples and cured with an LED for 10 s. The samples prepared for the repair procedure were divided into two subgroups (microhybrid composite and injectable composite) according to the viscosity of the repair material to be used (n = 12). After the repair procedure, care was taken to keep the samples in distilled water in an incubator at 37 °C for 24 h. The repair micro-shear bond strength values (µSBSs) of CAD/CAM resin nanoceramic-composite resin complexes were tested. In addition, randomly selected samples from each group were examined with a scanning electron microscope to evaluate the surface topography after both surface treatments and the micro-shear bond strength test. Data were analyzed by two-way ANOVA and Bonferroni test. It was determined that the surface treatment preferred in the repair protocol significantly affected the µSBS value (p < 0.001). While the highest µSBS value was obtained with the short-pulse laser airradiation group, the lowest µSBS values were found in samples with long pulse laser irradiation. However, samples grinded with a bur and airborne-particle abrasion showed similar µSBS values (p > 0.05). The preferred composite viscosity in the repair procedure has a significant effect on the µSBS value (p < 0.001). However, the interaction between the surface treatment and the viscosity of the repair composite does not affect the µSBS values in a statistically significant way (p = 0.193). It may be recommended to clinicians to repair CAD/CAM resin nanoceramic restoration surfaces with injectable composites or after treatment with short-pulse lasers.

Carbon nanotube-modified adhesive to caries affected dentin conditioned with Nd: YAP laser, Phosphoric acid, and Photoactivated-erythrosine.

AIM: DENTIN CONDITIONED: with phosphoric acid (PA) Nd: YAP laser, and photoactivated-Ery(Erythrosine) on microleakage, shear bond strength (SBS) degree of conversion (DC), and rheological assessment of adhesive-infused with carbon nanotubes (CNTs). MATERIAL AND METHOD: Carious ninety-six human mandibular molars were included. Specimens were disinfected and allocated into three groups based on surface pretreatment (n=32) Group 1 (PA), Group 2 (Nd: YAP) laser, and Group 3 (Photoactivated-Ery). Conditioned groups were further divided into two 2 subgroups based on the application of unmodified ERA and CNTs-modified ERA. Composite restorations were placed on the CAD surface and thermal aging of the samples was performed. The microleakage assessment was conducted using a dye penetration test. Universal testing machine (UTM) assessed SBS bond failure was evaluated using a stereomicroscope. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analyses of CNT, and Fourier Transform Infrared FTIR of adhesives were performed. One-way ANOVA and Tukey post hoc analyzed the outcomes. RESULTS: Group 1B samples (PA+ CNTs modified adhesive) presented the minimum marginal leakage and highest bond integrity. Group 2A (Nd:YAP laser+Unmodified adhesive) displayed the maximum scores of microleakage and lowest bond strength. CONCLUSION: Photoactivated Ery-PS can serve as an alternative to phosphoric acid for conditioning CAD. Incorporating CNT in adhesive significantly enhanced bond integrity and marginal seal with no significant difference in DC.

Enamel Deproteinization or Sandblasting for Enamel Reconditioning Before Acid Etching to Enhance the Shear Bond Strength of Metallic Brackets in a Third Bonding: An In Vitro Study.

BACKGROUND: Enamel conditioning with 37% phosphoric acid is the most common technique during orthodontic bracket bonding procedures. However, due to the repeated de-bonding of the orthodontic brackets during treatment, other methods were needed to condition the enamel surface and increase the bond strength. This study aimed to compare the effect of conditioning the enamel surface by sandblasting with aluminum oxide particles or 5.25% sodium hypochlorite gel in combination with acid etching compared to acid etching alone on shear bond strength (SBS). MATERIAL AND METHODS: One hundred eight extracted upper premolars were randomly divided into three groups according to the conditioning enamel surface method. After the first and second bonding of metal brackets, new metal brackets were bonded with a total-etching adhesive after enamel conditioning using different methods: acid etching only (37% phosphoric acid for 30 seconds) (AE group), sodium hypochlorite associated with acid etching (5.25% NaOCl gel for 60 seconds and then acid etching for 30 seconds) (NaOCl-AE group), and sandblasting associated with acid etching (sandblasting for five seconds and then acid etching for 30 seconds) (SB-AE group). The shear bond strengths of the brackets were tested with a universal testing machine. One-way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) tests were used to detect significant differences in shear bond strength among groups at the third bonding. Repeated-measure ANOVA and Bonferroni's tests were used to detect significant differences in shear bond strength among the bonding attempts within each group. RESULTS: 5.25% sodium hypochlorite associated with the acid etching method produced significantly greater shear bond strength than sandblasting associated with acid etching and acid etching only methods at the third bonding (16.40 ± 5.80 MPa, 13.60.47 ± 6.40 MPa, and 9.90 ± 4.40 MPa, respectively; P < 0.001). However, there was no significant difference between the AE and SB-AE groups (P = 0.247). In addition, we found a significant decrease in the shear bond strength within each group after each bonding attempt. CONCLUSION: Conditioning the enamel surface with 5.25% sodium hypochlorite associated with acid etching produced greater bond strength than conditioning by sandblasting associated with acid etching and acid etching only at the third bonding. The bond strength of the metal bracket decreased with increasing bonding attempts, even with the application of enamel surface conditioning methods.

Comparative Evaluation of the Effect of Different Types of Bleaching Dentifrices on Shear Bond Strength of Orthodontic Metal Brackets Bonded by Conventional Composite to Human Teeth: An In Vitro Study.

AIM: This study aims to evaluate and compare the effect of different types of bleaching dentifrices on the shear bond strength of orthodontic metal brackets bonded by light-cured composite adhesive to human teeth. MATERIALS AND METHODS: Forty-five human premolar teeth were randomly divided into three groups, receiving the following treatments: Group 1 (control group; teeth in this group were not bleached), Group 2 (teeth in this group were treated with active oxygen bleaching dentifrice), and Group 3 (teeth in this group were treated with peroxide bleaching dentifrice). Orthodontic brackets were bonded using a light-cured composite adhesive. A universal measuring device was used to assess the shear bond strength with a crosshead speed of 0.5 mm/min. One-way ANOVA, post hoc Tukey tests, and an independent t-test were used to analyse the data. RESULTS: There was a highly significant difference (p≤0.001) in the mean shear bond strength of orthodontic brackets bonded to untreated teeth as compared to teeth treated with bleaching dentifrice. There was no significant difference in the mean shear bond strength of orthodontic brackets bonded to teeth treated with peroxide bleaching dentifrice or active oxygen bleaching dentifrice. CONCLUSION: There was a significant reduction in the mean shear bond strength of orthodontic metal brackets when bonded to human teeth treated with bleaching dentifrices.

The effect of antimicrobial peptide-added adhesive resins on shear bond strength and the adhesive remnant index of orthodontic brackets.

OBJECTIVES: The aim of this study was to evaluate the effect of in-vivo produced Nisin which is an antimicrobial peptide (AMP) added to adhesive resin on shear bond strength (SBS) and the adhesive remnant index (ARI) of orthodontic brackets. METHODS: Bacterial AMP was produced by fermentation and the ideal AMP/Bond concentration and antimicrobial efficacy of the mixture were tested. To evaluate the SBS and ARI scores of AMP-added adhesive resins, 80 maxillary premolar teeth extracted for orthodontic purposes were used and randomly assigned into 2 groups (n = 40). Group 1: Control Group (teeth bonded with standard adhesive resin); Group 2: Experimental Group (teeth bonded with AMP-added adhesive resin). Statistical analysis was performed using the SPSS package program and applying the Mann-Whitney U and Fisher's exact tests. P < 0.05 was considered as statistically significant. RESULTS: Nisin synthesized in-vivo from Lactococcus lactis (L. lactis) (ATCC 7962) bacteria was provided to form a homogenous solution at an ideal concentration To find the minimum AMP/Bond mixture ratio that showed maximum antimicrobial activity, AMP and Bond mixtures were tested at various concentration levels between 1/160 and 1/2 (AMP/Bond). As a result, the optimum ratio was determined as 1/40. The antimicrobial efficacy of Nisin-added adhesive resin was tested against Streptococcus mutans (S. mutans) (ATCC 35,688) and Lactobacillus strains (cariogenic microorganisms). AMP formed a 2.7 cm diameter zone alone, while 1/40 AMP-bond mixture formed a 1.2 cm diameter zone. SBS values of the teeth bonded with Nisin added adhesive (17.49 ± 5.31) were significantly higher than the control group (14.54 ± 4.96) (P = 0.004). According to the four point scale, Nisin added adhesive provided a higher ARI score in favour of the adhesive and tooth compared to the control group (ARI = 3, n = 20). CONCLUSIONS: Nisin produced from L. lactis (ATCC 7962) had greater antimicrobial effects after mixing with adhesive bond against cariogenic microorganisms S. mutans (ATCC 35,688) and Lactobacillus strains. Nisin added adhesive increased shear bond strength (SBS) of orthodontic brackets and ARI scores in favor of adhesive & teeth. CLINICAL RELEVANCE: Clinicians should take into account that using Nisin-added adhesive resin in orthodontic treatments can provide prophylaxis against tooth decay, especially in patients with poor oral hygiene.

Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study.

AIM: The purpose of this study was to evaluate the effectiveness and strength of three various dentin-bonding agents used with adhesives on primary teeth. MATERIALS AND METHODS: The study used 80 recently extracted, healthy human maxillary anterior primary teeth that had undergone physiologic resorption, or over-retention. Teeth were cut to expose a flat dentin surface at a depth of 1.5 mm. All samples were divided into four groups (20 samples in each group) as follows: Group I-Control group, Group II-Primary teeth bonding with 6th-generation bonding agent, Group III-Primary teeth bonding with 7th-generation bonding agent, Group IV-Primary teeth bonding with 8th-generation bonding agent. All of the samples' dentinal surfaces were covered with composite resin using a Teflon mold after adhesive had been applied. A universal testing machine (INSTRON) was used to assess the shear bond strength. Data were collected and statistically analyzed. RESULTS: The maximum mean shear bond strength was found in 8th-generation bonding agent (30.76 ± 0.16), followed by 7th-generation bonding agent (26.08 ± 0.21), 6th-generation bonding agent (25.32 ± 0.06), and control group (6.18 ± 0.09). Statistically significant difference was found between the three different bonding agents (p < 0.001). CONCLUSION: On conclusion, the 8th-generation bonding agent demonstrated a greater shear bond strength to dentin than the 7th and 6th-generation bonding agent. CLINICAL SIGNIFICANCE: The emergence of different bonding techniques to the market improves the durability and quality of restorations. An effective bonding to the tooth would also reduce bacterial penetration, marginal microleakage, possibility of pulpal inflammation preserve tooth structure, and postoperative sensitivity by allowing less cavity preparation. How to cite this article: Alqarni AS, Al Ghwainem A. Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study. J Contemp Dent Pract 2024;25(4):342-345.

A comparative evaluation of the effect of eugenol exposure time on the bond strength of an etch-and-rinse and a self-etch adhesive to dentin: An in vitro study.

Aim: The study aimed to comparatively evaluate the effect of eugenol exposure time on the micro-shear bond strength (µ-SBS) of etch-and-rinse and a self-etch adhesive to dentin. Materials and Methods: One hundred and twelve teeth samples were prepared from bisectioning 56 freshly extracted human mandibular molars and were randomly divided into 14 subgroups of 8 samples each (n = 8). Three subgroups containing eugenol and a noneugenol-based restorative material were placed on the dentin surface and left for 24 h, 7 days, and 14 days, respectively, and were compared to a control. Two bonding systems were evaluated: one being etch-and-rinse and the other self-etch adhesive. The µ-SBS were calculated and expressed in MPa. Statistical Analysis: The data were analyzed using mixed model analysis of variance. The level of statistical significance was set at 5%. Results: There was a statistically significant reduction in the µ-SBS values when the self-etch adhesive was used, after the removal of eugenol-containing cement placed for 24 h. However, the reduction in the µ-SBS values after 7 days or 14 days was not significant. Conclusion: Exposure to eugenol containing temporary cement for 24 h significantly reduces the µ-SBS of self-etching adhesives to dentin. However, exposure for 1 week or more has minimal effects.

Shear bond strength of orthodontic brackets to single-shade composite surfaces: An in-vitro comparative study of different surface preparations.

PURPOSE: The primary objective of this study was to determine which single-shade composite surface yielded clinically acceptable shear bond strength (SBS) to metal orthodontics brackets. The secondary objectives were to identify the best composite surface treatment to enhance SBS and determine which surface treatment produced the least surface damage at debond. METHODS: Forty dental composite samples were selected from four different manufacturers (n=160) and grouped by manufacturer, one standard multi-shade dental system (FilTek™ Supreme Ultra) and three single-shade dental composites systems (OmniChroma®, SimpliShade™ and Venus® Diamond One). Each group of forty samples was randomly divided into four sub-groups (n=10). Each sub-group was identified by the surface treatment used, hydrofluoric acid (HFA), micro-etching (MIC), or phosphoric acid (PA). Shear bond strength testing and adhesive remnant index (ARI) were performed. Statistical analyses included Kruskal-Wallis, Wilcoxon rank-sum, and two-factorial ANOVA. RESULTS: OmniChroma® had statistically significant lower shear bond strength than the other composite materials tested. The control groups had statistically significant lower shear bond strength than Group 1/HFA (P<0.001) and Group 2/MIC (P<0.001). Group 1/HFA had the lowest distribution ARI score overall, while MIC had the highest ARI score distributions. CONCLUSIONS: The results of this in-vitro study found that all tested composite materials achieved clinically acceptable shear bond strengths. The utilization of micro-etching produced higher SBS. Significant Adhesive Remnant Index scores (< 0.001) were only found for OmniChroma® without any surface preparation.

Shear Bond Strength of Orthodontic Brackets Bonded with Thermo-Cured Glass-Based Materials-An In Vitro Study.

The results of orthodontic therapy largely depend, among other factors, on the preparation of the tooth enamel itself and the choice of material used to bond orthodontic brackets. The aim of this in vitro study was to determine the shear bond strength (SBS) and adhesive remnant index (ARI) score of thermo-cured glass-ionomers on different pretreated enamel, in comparison with the commonly used composite cement. Three commercially available nano-ionomer or highly viscous glass-ionomer cements (EQUIA Forte® Fil, EQUIA Fil, Ketac Universal) and two types of compo-sites (Heliosit Orthodontic, ConTec Go!) were investigated in this study. The research involved two hundred human premolars. The teeth were cleaned and polished, then randomly divided into five groups according to the enamel preparation method and the type of material. The enamel was treated in three different ways: polyacrylic acid, phosphoric acid, 5% NaOCl + etching with phosphoric acid, and a control group without treatment. Glass-ionomer cement was thermo-cured with heat from a polymerization unit during setting. Statistical analysis was performed using a Chi-square test and one-way ANOVA for independent samples. Spearman's Rho correlation coefficient was used to examine the relationship. Regardless of the material type, the results indicated that the weakest bond between the bracket and tooth enamel was found in samples without enamel pretreatment. The majority of the materials stayed on the brackets in samples without enamel preparation, according to ARI scores. The study's findings demonstrated that the strength of the adhesion between the bracket and enamel is greatly influenced by enamel etching and glass-ionomer thermo-curing. Clinical investigations would be required to validate the outcomes.

Effects of Surface-Etching Systems on the Shear Bond Strength of Dual-Polymerized Resin Cement and Zirconia.

Adhesion of zirconia is difficult; thus, etching agents using several different methods are being developed. We investigated the effects of surface treatment with commercially available etching agents on the bond strength between zirconia and resin cement and compared them with those achieved using air abrasion alone. We used 100 zirconia blocks, of which 20 blocks remained untreated, 20 blocks were sandblasted, and 60 blocks were acid-etched using three different zirconia-etching systems: Zircos-E etching (strong-acid etching), smart etching (acid etching after air abrasion), and cloud etching (acid etching under a hot stream). Each group was subjected to a bonding procedure with dual-polymerized resin cement, and then 50 specimens were thermocycled. The shear bond strengths between the resin cement and zirconia before and after the thermocycling were evaluated. We observed that in the groups that did not undergo thermocycling, specimens surface-treated with solution did not show a significant increase in shear bond strength compared to the sandblasted specimens (p > 0.05). Among the thermocycled groups, the smart-etched specimens showed the highest shear bond strength. In the short term, various etching agents did not show a significant increase in bond strength compared to sandblasting alone, but in the long term, smart etching showed stability in bond strength (p < 0.05).

Adhesive Performance of Pit and Fissure Sealants on Deproteinized Enamel with Different Proteolytic Agents: In Vitro Study.

The objective of this work was to assess the efficacy of different proteolytic agents on the bond strength of pit and fissure sealants to bovine enamel. Eighty-four bovine enamel specimens were randomly assigned in groups according to the pit and fissure sealant applied (HelioSeal F or Dyad Flow). Then, the specimens were subdivided according to the proteolytic agent used (n = 7): Group 1, distilled water (control); Group 2, 10 wt.% Tergazyme®; Group 3, 10 wt.% ZYME®; Group 4, 10% papain gel; Group 5, 10% bromelain gel; and Group 6, 5.25 wt.% sodium hypochlorite. The cell viability of the proteolytic solutions was assessed through the MTT assay. The proteolytic agents were applied on the enamel surface prior to the acid-etching procedure; then, the pit and fissure sealants were placed. The micro-shear bond strength was evaluated after 24 h or 6 months of water storing at 37 °C. Representative SEM images were taken for each experimental group. The bond strength data were statistically analyzed by a three-way ANOVA test using a significance level of α = 0.05. Bromelain and papain proteolytic solutions did not exert any cytotoxic effect on the human dental pulp cells. After 24 h and 6 months of aging, for both pit and fissure sealants, sodium hypochlorite, papain, bromelain, and Tergazyme® achieved statistically significant higher bond strength values (p < 0.05). Irrespective of the deproteinizing agent used, Dyad Flow resulted in a better bond strength after 6 months of aging. The type 1 etching pattern was identified for sodium hypochlorite, papain, and bromelain. Tergazyme®, papain, and bromelain demonstrated efficacy in deproteinizing enamel surfaces prior to acid etching, leading to the improved bond strength of pit and fissure sealants. Clinically, this suggests that these proteolytic agents can be considered viable alternatives to traditional methods for enhancing sealant retention and longevity. Utilizing these agents in dental practice could potentially reduce sealant failures.

Shear Bond Strength of Clear Aligner Attachment Using 4-META/MMA-TBB Resin Cement on Glazed Monolithic Zirconia.

Increasing demand for adult orthodontic treatment using clear aligners has highlighted challenges in bonding clear aligner attachments to various restorations. Specifically, the bond strength of clear aligner attachments to glazed monolithic zirconia has not been extensively studied. This study aims to compare the shear bond strength (SBS) and mode of failure (MOF) of conventional bonding methods versus Superbond C&B (4-META/MMA-TBB resin cement) for clear aligner attachments on glazed monolithic zirconia. Fifty sintered and glazed zirconia samples were divided into five groups and attached with clear aligner attachments: Si (silane), B (bonding agent), SiB (bonding agent and silane), SU (Superbond C&B), and SiSU (silane and Superbond C&B). SBS and MOF of these samples were analyzed. Results indicated a significant difference in bond strength among the groups. SiSU exhibited the highest bond strength, followed by SU, while B had the lowest bond strength. SEM analysis revealed that SiSU and SU predominantly exhibited mixed failure, indicating high bond strength without affecting the glazed layers of the zirconia. In contrast, B exhibited only adhesive failure at the interface, resulting in insufficient bond strength for effective orthodontic treatment. In conclusion, using 4-META/MMA-TBB resin cement provides high bond strength for clear aligner attachments on glazed zirconia with minimal material damage during debonding.

Effects of different plasma treatments on bonding properties of zirconia.

This in vitro study was to evaluate the effect of different non-thermal atmospheric pressure plasma (NTP) on shear bond strength (SBS) between yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and self-adhesive resin cement. In this study, The Y-TZP specimens were divided into 4 groups according to the surface treatment methods as follows: Control (no surface treatment), Sb (Sandblasting), AP(argon NTP), and CP(20 % oxygen and 80 % argon combination NTP). Y-TZP specimens were randomly selected from each group to observe and test the following indexes: scanning electron microscope to observe the surface morphology; atomic force microscope to detect the surface roughness; contact angle detector to detect the surface contact angle; energy spectrometer to analyze the surface elements. Then, resin cement (Rely X-U200) was bonded to human isolated teeth with Y-TZP specimens to measure SBS. The results showed that for the SE test, the NTP group was significantly higher than the control group (p < 0.05). The results of the SBS test showed that the SBS values of the NTP group were significantly higher than those of the other groups, regardless of the plasma treatment (p < 0.05). However, there was no significant difference between groups AP and CP in a test of SBS (p > 0.05). This study shows that non-thermal atmospheric pressure plasma can improve the shear bond strength of Y-TZP by increasing the surface energy. The addition of oxygen ratio to argon is more favorable to increase the shear bond strength and is worth further investigation.

Effect of Different Adhesive Resin and Composite Veneering Materials on Adhesion to Polyetheretherketone.

OBJECTIVE: To evaluate the effect of different adhesives and veneering resins on the shear bond strength (SBS) of polyetheretherketone (PEEK). METHODS: A total of 138 PEEK specimens were randomly divided into 6 groups according to adhesive material application: Control (C, no application), Adhese Universal (A) (Ivoclar Vivadent, Schaan, Liechtenstein), Gluma Bond Universal (G) (Heraeus Kulzer, South Bend, IN, USA), G-PremioBOND (P) (GC Corporation, Tokyo, Japan), Single Bond Universal (S) (3M, Saint Paul, MN, USA) and visio.link (V) (Bredent, Senden, Germany). Each adhesive group was divided into two subgroups according to the type of veneering material: Estenia direct composite (D) and Gradia Plus indirect composite (IN) (both GC Corporation). After the veneering process, the specimens were aged by thermal cycling. Kruskal-Wallis and Mann-Whitney U tests were used for SBS analysis (P < 0.05). RESULTS: The highest SBS results were obtained in the VIN group, followed by the VD, PD, GIN, AIN, AD, SIN, SD, PIN, GD, CIN and CD groups, respectively (P = 0.001). There were no significant differences in terms of the type of veneering composite when the same adhesive was applied (P > 0.05), except for Gluma Bond Universal (P = 0.009). All the adhesives tested showed clinically acceptable SBS results. CONCLUSION: Visio.link offered the highest adhesion to PEEK, whereas the tested universal adhesives may be used as an alternative to visio.link in clinical settings. It was determined that changing the veneer type has no statistical difference when the same adhesive material is used.

In vitro effect of zirconia type on shear bond strength to feldspathic porcelain and wear of the opposing teeth.

Background: Multilayer zirconia has more optical and aesthetic features than regular zirconia. Therefore, its mechanical properties should be compared with monochromatic zirconia. Among the mechanical characteristics that can be checked are the wear of the opposite tooth and the bond to the porcelain. This study assessed the effect of zirconia type (multilayer versus monochromatic) on the shear bond strength (SBS) to feldspathic porcelain and the wear of the opposing teeth. Methods: The present in vitro study was conducted in two phases. In the first phase, 15 multilayer and 15 monochromatic zirconia blocks measuring 10×5×5 mm were designed, milled, sintered, veneered with porcelain, and underwent thermocycling. Their SBS was then measured in a universal testing machine. In the second phase, 15 multilayer and 15 monochromatic zirconia blocks were placed in a chewing simulator, and 30 sound premolars served as antagonistic teeth. The magnitude of wear of the buccal cusp of premolars was quantified from a 4-mm reference point after 100000 cycles. Data were analyzed by independent t test (α=0.05). Results: The mean SBS of monochromatic zirconia to porcelain (24.49±3.58 MP) was slightly higher than that of multilayer zirconia (22.98±2.98 MP), but the difference was not significant (P>0.05). The mean wear of the opposing teeth was also slightly higher in the monochromatic group (284.1±66.53 µm) than in the multilayer group (263.2±58.69 µm), but this difference was not significant either (P>0.05). Conclusion: Monochromatic and multilayer zirconia showed comparable SBS to feldspathic porcelain and caused comparable wear of the opposing teeth in vitro. Thus, multilayer zirconia may serve as an alternative to monochromatic zirconia.

Comparison of shear bond strength of different types of intracanal posts in restoring extensively damaged primary anterior teeth.

Background: Severe caries in early childhood is a concern for both children receiving dental treatment and their parents. This dental disease progresses rapidly and quickly damages the coronal part of the tooth. When there is insufficient coronal structure to support a coronal restoration, using intracanal components following root canal treatment increases tooth resistance and helps provide retention for the coronal restoration. This study compared the shear bond strength of three types of intracanal posts (composite resin post, reverse metal post, and fiber post) in severely damaged primary anterior teeth. Methods: This in vitro study was conducted on 30 extracted anterior primary teeth with at least two-thirds of healthy roots and no prior pulp treatment. The teeth were randomly divided into three groups of 10: group 1: composite resin post with 8th generation universal bonding, group 2: reverse metal post with GC restorative glass cement, and group 3: fiber post with GC restorative glass cement. After placing the post, the samples were restored with a height of 3 mm from cementoenamel junction (CEJ) using an Anterior GC Gradia Packable composite resin. All the samples underwent 500 cycles of thermocycling in a hot water bath at 55±2 °C and a cold water bath at 5±2 °C. The shear strength of the samples was then evaluated using an electromechanical universal testing machine at a rate of 1 mm/min and at a location 2 mm coronal to the CEJ in terms of megapascals. Results: The average shear bond strength of composite resin posts with 8th generation bonding application was 8.02220 MPa, reverse metal posts with glass ionomer application was 13.8600 MPa, and fiber posts with glass ionomer application was 9.7400 MPa. Conclusion: Based on these findings, it can be concluded that the highest shear bond strength in this study was related to the reverse metal post, and the lowest shear bond strength was related to the composite resin post. According to the results, reverse metal posts demonstrated better shear bond strength than composite resin posts and fiber posts (P<0.05).

Biaxial flexural strength of nanoglass and multiwalled carbon nanotubes reinforced 3D-printed denture base resins and their shear bond strength to 3D-printed and acrylic denture teeth.

OBJECTIVE: Evaluation of biaxial flexural strength (BFS) of nanoglass (NG) and multiwalled carbon nanotubes (MWCNTs) reinforced 3D-printed denture base resins and their shear bond strength (SBS) to 3D-printed and acrylic denture teeth. METHODS: Silanized NG and MWCNTs were added to 3D-printed denture base resin to obtain four groups: Control, 0.25 wt% NG, 0.25 wt% MWCNTs, and a combination group with 0.25 wt% of both fillers. All specimens were tested before and after 600 cycles of thermal aging. BFS (n = 88) was tested using disk-shaped specimens (12 ×2 mm) centralized on an O ring in a universal testing machine. Weibull analysis was conducted to assess predictability of failure. SBS (n = 176) was tested for acrylic and 3D-printed denture teeth attached to bar-shaped specimens in a universal testing machine followed by failure mode analysis using stereomicroscope. Two and three-way ANOVA tests followed by Tukey post hoc test were conducted for BFS and SBS. Kruskal-Wallis test compared percent change among groups with subsequent Dunn post hoc test with Bonferroni correction (α = 0.05). RESULTS: BFS was affected significantly by filler content (P < 0.001) and thermal cycling (P < 0.001), with thermal cycling displaying the uppermost effect (È p2 =0.551). A significant interaction between filler content, thermal cycling, and teeth type was displayed by SBS results (P < 0.001, F=10.340, È p2 =0.162). The highest BFS values belonged to 0.25 % MWCNTs while the highest SBS to printed teeth was displayed by the combination. SIGNIFICANCE: The combination group displayed higher BFS and SBS to printed teeth compared to control which allows 3D-printed materials to have a long-term clinical success.

Experimental and Chitosan-Infused Adhesive with Dentin Pretreated with Femtosecond Laser, Methylene Blue-Activated Low-Level Laser, and Phosphoric Acid.

Aim: To prepare experimental adhesive (EA) with 1% and without chitosan nanoparticles on dentin conditioned with a conventional technique phosphoric acid (PA) compared with two different contemporary techniques: photodynamic therapy (PDT) and femtosecond laser (FSL). Method: The methodology consisted of synthesis of EA and 1% chitosan-modified adhesive (CMA). Scanning electron microscopy, dentin adhesive interface assessment, energy-dispersive spectroscopy, shear bond strength (SBS), degree of conversion (DC), and bond failure were assessed. Teeth were selected, disinfected, and mounted in acrylic up to the cementoenamel junction. Occlusal enamel was removed and teeth were randomly allocated into groups and conditioned. These included Group 1: samples treated with PA; Group 2: specimens conditioned with methylene blue photosensitizer (MBP) activated by PDT; and Group 3: samples conditioned with FSL. Following different conditioning regimes, specimens were bonded using 1% CMA and EA. The composite buildup was followed by SBS testing and a bond failure assessment. DC was assessed for both EA and CMA. Analysis of variance and Tukey's post hoc test were used to compare the mean and standard deviation of SBS and DC in different experimental groups, with a significance level of p < 0.05. Results: Dentin pretreated with etch and rinse demonstrated the highest bond strength with 1% CMA. Dentin conditioned with MBP activated by PDT and bonded to EA showed the lowest bond scores. Overall SBS values of 1% CMA were better than EA irrespective of the conditioning regime of dentin. The DC was higher in EA adhesive. This was followed by DC in 1% CMA. DC in EA was found to be comparable with 1% CMA. Conclusions: PA remains the gold standard for dentin conditioning. The incorporation of 1% chitosan in adhesive improves SBS and results in no change in DC. The use of FSL in dentin conditioning can be used as an alternative approach as it results in SBS within acceptable limits. The study was approved by the ethical board of King Saud University.