Flat Dentin Research Articles

Influence of dentin moisture conditions on the wetting action of different endodontic sealers using Rame-Hart goniometer: An in vitro study

Aim: To evaluate the influence of different dentin moisture conditions on the wetting action of different classes of endodontic sealers, that is, Bioceramic based sealer – Smart Paste Bio, Resin based sealer - AH Plus and Zinc oxide eugenol based sealer – Tubliseal. Materials and Methods: The present research is an in vitro comparative study in which the samples were selected by random sample method. A total of 54 dentin samples were prepared by longitudinally sectioning 27 freshly extracted single rooted mandibular first premolars. 54 samples were then allocated into three groups of 18 each based on the sealer used. Irrigation of the dentin samples were done with 5.25% sodium hypochlorite followed by 17% EDTA and a final rinse with distilled water.18 samples in each sealer group were further divided into separate subgroups of six each on the wide variety of dentin moisture conditions subjected to dry, moist and wet conditions. 0.1ml of sealer was deposited on flat dentin surface and contact angles were measured. Statistical evaluation was done using Analysis of variance and Post-hoc Tukey test at 95% confidence interval and P value <0.05 was considered statistical significant. Results: One way ANOVA was done to analyse the statistical significant difference between the wetting ability of three different sealers under different moisture condition the P Value was <0.001 which was considered statistically significant. Post hoc Tukeys test was done to analyze the contact angle between the two groups in dry, moist and wet condition with P value =0.001 which is <0.05 hence there is a statistical significant difference among all the subgroups. Conclusion: Within the limitation of this in vitro study it can be concluded that the wetting behavior of Resin based sealer - AH Plus was significantly better than Bioceramic sealer - Smart Paste Bio and Zinc oxide eugenol sealer - Tubliseal during dry and moist dentin conditions.

Comparative Evaluation of Shear Bond Strength of Bioactive Restorative Material, Zirconia Reinforced Glass Ionomer Cement and Conventional Glass Ionomer Cement to the Dentinal Surface of Primary Molars: an in vitro Study.

Statement of the Problem: The success of dental restorations depends mainly on its ability to bond to dental structures and resist the multitude of forces acting on it within the oral cavity.Purpose: Therefore, the aim of this study was to evaluate the shear bond strength (SBS) of three different glass ionomer based restorative materials.Materials and Method: In this in vitro analytical study, 30 intact primary molars were sectioned buccolingually to obtain 60 sections. These sections were embedded in auto polymerizing acrylic resin and polished to obtain a flat dentin surface. Restoration cylinders were built on the dentin surface with the help of a Teflon template called bonding jig. Each group (n= 20) was restored as group A with conventional glass ionomer cement (GIC) (GC Fuji Gold Label Type 9), group B with Bioactive restorative material (ACTIVATM KIDS BioACTIVE Restorative material), and group C with Zirconia reinforced glass ionomer cement (Zirconomer). Following restoration, SBS testing was performed using Universal Testing Machine. The data obtained were statistically analyzed using One way ANOVA test and post hoc Tukey test (p= 0.05).Results: The SBS values were significantly greater in the ACTIVA KIDS group as compared to the other two groups (p< 0.05). There was no significant difference in the SBS values between group B and group C (p> 0.05).Conclusion: The SBS of the ACTIVA KIDS to primary teeth dentin was the highest as compared to Zirconomer and conventional GIC. Therefore ACTIVA KIDS may protect primary teeth against recurrent caries and failure of the restoration.

Mechanical Stability and Proteolytic Activity of Resin–dentin Bonds Using the Cross-linked Dry Bonding Technique

To evaluate the mechanical stability and the proteolytic activity of bonds created by a two-step, etch-and-rinse adhesive applied to cross-linked and air-dried etched dentin. Flat dentin surfaces were produced in 64 extracted sound human molars. The dentin was etched with 35% phosphoric acid for 15 seconds, and then the teeth were divided into groups according to the cross-linking solution applied on the etched dentin. Group 1: 5% grape seed extract (GSE), Group 2: 5% glutaraldehyde, Group 3: Gluma Desensitizer, or Group 4: deionized water (control). Solutions were applied for 60 seconds, followed by rinse and blot drying. Then, the teeth were separated into two subgroups where the etched dentin was kept moist or air-dried. The adhesive was applied followed by a composite resin buildup. After 24 hours, the teeth were cut into beams (0.81 mm²) that were tested for microtensile strength immediately or after 12 months of aging in a 37°C saliva-like buffer. Additional teeth (n=32) were bonded as described and cut into 0.5-mm-thick slabs. The slabs were prepared for nanoleakage (scanning electron microscopy) and in situ zymography (EnzChek Protease Assay Kit). Bond strength data were submitted to ANOVA and Tukey tests (α =0.05). Significant reduction in immediate bond strength (ca 65%) and increase in proteolytic activity was seen when the etched dentin was air dried without previous cross-linking biomodification. Conversely, bond strengths did not differ from those produced on wet dentin when collagen was cross-linked before air drying, irrespective of the solution applied. For both moist and air-dried etched dentin, collagen cross-linking resulted in mechanically stable bonds and reduced proteolytic activity after 12 months of storage. Bonds produced by the application of a two-step, etch-and-rinse adhesive to cross-linked, air-dried, etched dentin were mechanically stable and revealed reduced proteolytic activity after 1 year of aging.

Effect of Curcumin Suspension and Vitamin C on Dentin Shear Bond Strength and Durability. A Pilot Study

Background: Preserving the strength and durability of dentin bonds is a concern of dental researchers and practitioners. Objective: The aim of this study was to investigate the effect of treating etched dentin with vitamin C and curcumin suspension as cross-linking agents on the shear bond strength and durability of a universal dental adhesive. Methods: Extracted human third molar teeth were collected. Fifty-six flat coronal dentin surfaces were divided equally into four groups: (1) treated with adhesives; (2) etched with 37% H3PO4 for 10s before application of adhesives; (3) same as group (2), but with dentin treated with 2.5% curcumin suspension for 60s before the application of adhesive; and (4) same as group (3), but with the use of a 20% vitamin C suspension instead of a curcumin suspension. Filtek Z350XT composite was built for all samples. Half of the samples in each group were subjected to thermocycling. Shear bond strength was measured using a universal testing machine. Scanning electron microscopy was used to investigate the dentinal surfaces after treatment. Results: Treatment with curcumin suspension preserved immediate and long-term bond strength. Conversely, treatment of etched dentin with vitamin C solution significantly reduced the immediate bond strength, but a significant improvement was observed after aging. SEM showed that both cross-linking agents resulted in narrowing or closing of the dentinal tubules, with an adhesive mode of failure. Conclusion: The application of curcumin or vitamin C suspension to acid-etched dentin resulted in different effects on immediate and long-term shear bond strength when using universal adhesives.

Effect of Silver Diamine Fluoride Pretreatment on Shear Bond Strength of Resin Modified Glass Ionomer Cement to Primary Dentin

AIM: The aim of the study was to evaluate effect of silver diamine fluoride (SDF) on the shear bond strength (SBS) of glass ionomer restoration to primary dentine. MATERIALS AND METHODS: Twenty extracted primary molars with no restorations or developmental anomalies were only chosen for the study. Twenty dentine slices with 2 mm thickness were prepared and then randomly allocated into two groups (n = 10 per group). For Group 1 (experimental): Dentine surfaces were treated with 38% *SDF solution (Elevate oral care, USA) for 3 min using micro-brush, followed by a 30 s rinse with water and Group 2 (Control): Dentine surfaces were treated with distilled water for 3 min then rinsed for 30 s. The cavity conditioner was applied to flat dentin of both groups for 10 s then washed and dried gently with compressed air. All the specimens were restored with *RMGIC (Riva Light Cure, SDI, Australia). SBS was determined using a Universal Testing machine and Failure mode was evaluated using stereomicroscope. Data were collected and statistically analyzed. Independent t test was used to assess differences in SBS between study groups and mode of failure was analyzed using Fisher’s exact test. Level of significance was set at p ≤ 0.05. IBM SPSS statistical software (version 26) was used to analyze the data. RESULTS: The experimental group had significantly higher mean of shear bond (11.92 ± 3.35) strength than the control group (6.99 ± 2.98) (p = 0.003). CONCLUSIONS: Primary dentin pre-treatment with 38% SDF increases the shear bond strength between RMGIC and primary dentin according to the results of this in vitro study.

Effect of Cement Layer Thickness on the Immediate and Long-Term Bond Strength and Residual Stress between Lithium Disilicate Glass-Ceramic and Human Dentin

This study tested whether three different cement layer thicknesses (60, 120 and 180 μm) would provide the same bonding capacity between adhesively luted lithium disilicate and human dentin. Ceramic blocks were cut to 20 blocks with a low-speed diamond saw under cooling water and were then cemented to human flat dentin with an adhesive protocol. The assembly was sectioned into 1 mm2 cross-section beams composed of ceramic/cement/dentin. Cement layer thickness was measured, and three groups were formed. Half of the samples were immediately tested to evaluate the short-term bond strength and the other half were submitted to an aging simulation. The microtensile test was performed in a universal testing machine, and the bond strength (MPa) was calculated. The fractured specimens were examined under stereomicroscopy. Applying the finite element method, the residual stress of polymerization shrinkage according to cement layer thickness was also calculated using first principal stress as analysis criteria. Kruskal–Wallis tests showed that the ‘‘cement layer thickness’’ factor significantly influenced the bond strength results for the aged samples (p = 0.028); however, no statistically significant difference was found between the immediately tested groups (p = 0.569). The higher the cement layer thickness, the higher the residual stress generated at the adhesive interface due to cement polymerization shrinkage. In conclusion, the cement layer thickness does not affect the immediate bond strength in lithium disilicate restorations; however, thinner cement layers are most stable in the short term, showing constant bond strength and lower residual stress.

Effect of Contamination with Hemostatic Agent on Shear Bond Strength of Composite to Dentin Using G-Premio and Single Bond Universal Adhesives.

Objectives: Bond strength of composite restorations plays an important role in their success. This in vitro study evaluated the effect of a hemostatic agent on shear bond strength of universal adhesives. Materials and Methods: Thirty-six extracted human molars were used in this study. Buccal and lingual surfaces were reduced to obtain flat dentin surfaces and were ground with a silicone paper. The samples were randomly divided into three groups (n=12) based on the application of hemostatic agent: group 1: no contamination (control), group 2: aluminum chloride application, and group 3: ferric sulfate application. Each group was then divided into two subgroups (n=6) for using G-Premio and Single Bond Universal. Resin cylinders (Filtek Z550) were bonded to dentin surfaces according to the manufacturer’s instructions. After 1000 thermal cycles, shear load was applied to the specimens using a universal testing machine at a crosshead speed of 1 mm/min until failure. Data were statistically analyzed using two-way ANOVA and Tukey’s post-hoc test (α=0.05). Results: There were statistically significant differences in shear bond strength of the three main groups for both G-Premio and Single Bond Universal (P<0.05). When the adhesive systems were compared with each other, G-Premio showed higher shear bond strength than Single Bond Universal (P<0.05). Conclusion: Contamination with hemostatic agents had an adverse effect on the shear bond strength of universal adhesives. Moreover, G-Premio yielded a higher bond strength than Single Bond Universal.

The Ultra-morphological Evaluation of Conventional and Resin-Modified Glass Ionomer Cements Modified with Nano-Hydroxyapatite Particles at Sound and Caries-Affected Dentin Interfaces

Purpose: To assess the effect of incorporation of 5 wt% nano-hydroxyapatite particles (Nano-HAp) on the ultra-morphological characteristics of sound and caries-affected dentin substrate/ conventional glass ionomer cement (CGIC) and resin-modified glass ionomer cement (RMGIC) interfaces. Materials and Methods: Occlusal surfaces of 16 extracted permanent human caries-free molars were ground to expose flat dentin surfaces. Half of the specimens (n=8) were subjected to pH-cycling to create artificial caries-affected dentin. Specimens were randomly restored with one of the tested restorative materials either control (CGIC and RMGIC) or experimental (CGIC and RMGIC modified with Nano-HAp). Different restorative materials were mixed according to manufacturer instructions and then built-up on the sound or caries-affected dentin surfaces. All specimens were stored in artificial saliva either for 24 hours or 9 months. Specimens were then prepared and observed under field emission scanning electron microscope (FESEM) for ultra-morphological evaluation of dentin-restoration interfaces. Results: FESEM observations showed no marked ultra-morphological changes in Nano-HAp modified groups/ dentin interfaces in compared to control groups. There was significant increase in microcracks and pores within the matrix of all GIC groups. Moreover, there were multiples microcracks extended all over the restorations matrix with microgaps formation at dentin-restoration interfaces for all caries-affected dentin and 9 months aging period groups. Conclusion: The unique properties of glass ionomer cements were greatly diminished with bonding to caries-affected dentin and gradually declined with aging process. While there was no additional effect was observed from addition of Nano-HAp to these tested cements regarding their ultra-morphological characteristics features under FESEM.

Effects of adhesive application time and air blowing pressure on dentin bond strength of self-etch mode universal adhesives

The aim of this study was to investigate the effects of the active application time and air blowing pressure on the bond strength of universal adhesives. Three universal adhesive systems were used: Scotchbond Universal, Clearfil Universal Bond Quick, One coat 7 Universal. Flat dentin surfaces were obtained from 150 human molar teeth. The samples are randomly divided into groups according to the adhesives and the air blowing pressures (0.13 MPa, 0.27 MPa and 0.40 MPa) and then subdivided into groups according to different application times (5 s, 10 s, 20 s) (n = 5). For each adhesive system, a group without air blowing pressure was assigned as the control group (n = 5). The shear bond strength test was performed. Data were analyzed by ANOVA and Tukey HSD tests (p<0.05). There was no statistically significant difference in all variables and interactions except pressure variable (p<0.05). The bonding values of 0.13 MPa were significantly higher than 0.40MPa (p<0.05). Air blowing pressures have a significant effect on the bond strength of universal adhesive systems.

The Influence of Blade Type and Feeding Force during Resin Bonded Dentin Specimen Preparation on the Microtensile Bond Strength Test.

This paper presents the effect of blade type and feeding force during resin-bonded dentin specimen preparation on the microtensile bond strength (μTBS) test. Forty resin-bonded flat middle dentin specimens were divided into four groups. The specimens of each group were sectioned according to type of blade and feeding force as follows: fine grit/20 N, fine grit/40 N, medium grit/20 N, and medium grit/40 N to obtain resin-dentin sticks with a cross-sectional area of 1.0 mm2. Four sticks from the center of each tooth were subjected to the μTBS test. Five remaining sticks of each group were selected for surface topography observation under a scanning electron microscope (SEM). As a result, the bond strength of the medium-grit group was higher than that of the fine-grit group (p < 0.001), whereas the feeding force had no influence on bond strength values (p = 0.648). From the SEM, sticks prepared with the fine-grit blade showed a smoother surface integrity and fewer defects on the specimen edges in comparison with the sticks prepared with the medium-grit blade. The grit type of the blade is one of the considerable factors that may affect the bond strength and the surface integrity of resin-dentin specimens for microtensile testing.

Effect of Nd:YAG laser irradiation on microtensile bond strength of universal adhesives to dentin

The aim of this study was to evaluate the effect of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser irradiation before adhesive application on microtensile bond strength of resin composite to dentin surface. Materials and methods: in this experiment, 40 human extracted third molar teeth were chosen and the occlusal surface was cut to achieve a flat dentin surface. Groups were divided based on the adhesives (G-Premio Bond or Clearfil S3 Bond) and the presence or absence of Nd:YAG laser application. All the samples were restored with resin composite and subjected to a universal testing machine for a microtensile bond strength test. Fracture mode for each failure was analyzed under the stereomicroscope. According to the results, there was a significant difference between the two adhesives with Nd:YAG laser irradiation. The application of laser enhanced the microtensile bond strength in both adhesives. In all groups, regardless of laser application, adhesive failure was dominant between fracture patterns. It was concluded that Nd:YAG laser irradiation on dentin surface prior to adhesive application has a positive effect and significantly increases the microtensile bond strength of restoration to the tooth.

To etch or not to etch, Part I: On the fatigue strength and dentin bonding performance of universal adhesives

ObjectiveTo characterize whether the bonding performance and fatigue strength of resin-dentin interfaces created by a universal adhesive would be affected by different H3PO4-application times to more accurately assess long-term durability. MethodsMid-coronal flat dentin surfaces with standardized smear-layers were produced on sound third molars, etched with 32% H3PO4 for 0, 3 and 15 s, bonded with a mild universal adhesive (3M-ESPE) and restored with a nanofilled composite. Bonded specimens (0.9 × 0.9 mm) were stored in deionized water for 24 h and sectioned into beams for microtensile testing (n = 10). Resin-dentin beams were tested under tension until failure (0.5 mm/min) after 24 h or 6 month storage in artificial saliva at 37 ̊C. Bar-shaped resin-dentin beams (0.9 × 0.9 × 12 mm) were tested under 4-point-flexure initially at quasi-static loads (n = 22) and then under cyclic loads (n > 50). The stress-life fatigue behavior was evaluated using the twin-bonded interface approach by the staircase method at 4 Hz. Fractured interfaces and the tension side of unfractured beams were evaluated under SEM, along with the micro-morphology of the etched dentin surfaces and hybrid layers. Data were analyzed by ANOVA and Tukey test and Wilcoxon Rank Sum Test (α = 0.05). ResultsQuasi-static loads were limited to discriminate the bonding performance of resin-dentin interfaces. Application modes significantly affected etching patterns, fatigue strength, endurance limits and hybrid layer morphology (p < 0.001). SignificanceReductions in fatigue strength of self-etched bonded interfaces raise concerns about the true ability of universal adhesives to properly bond to dentin.

Mussel wet adhesion inspired using dopamine methacrylamide as a primer to improve dentin adhesion

This study aimed to evaluate whether a mussel wet adhesion inspired catechol-functionalized primer (dopamine methacrylamide, DMA) can increase microtensile bond strength (μTBS) of dentin–resin adhesion and improve the bonding interface in vitro. DMA was synthesized and characterized by proton nuclear magnetic resonance spectral analysis and high-resolution mass spectrometer analysis. A total of 50 flat dentin slabs of 50 human 3rd molars were prepared and allocated into two groups for DMA application (the DMA and experimental groups) and distilled water (the DW and control groups). The dentin slabs were etched by phosphoric acid and treated with either DMA or distilled water before bonding by using an etch-and-rinse adhesive system as standard clinical protocol (n = 20 in each group). μTBS test was performed before and after thermocycling (×2500 cycles at 5 °C and 55 °C). The morphology and quality of dentin/adhesive interfaces or the fractured interfaces were examined by scanning electron microscopy (SEM). Mean μTBS (MPa) values of the DMA group vs. the DW group were 27.10 ± 11.34 vs. 21.30 ± 6.06 (p < 0.05) before thermocycling and 25.75 ± 8.74 vs. 19.87 ± 6.59 (p < 0.05) after thermocycling. SEM observation of dentin–resin binding interface showed that the DMA group had lesser defects than the DW group. Our study revealed that mussel wet adhesion inspired catechol-functionalized DMA may increase the bonding strength and improve the integrity of the interface of dentin adhesive when used as a dental primer.

Lazerle Pürüzlendi̇ri̇len Denti̇n Yüzeyi̇ne Kompozi̇t Rezi̇nleri̇n Mi̇kro Bağlanma Dayanımlarının İncelenmesi

Objectives: The aim of this study is to determine the microtensile bond strength (µTBS) of two different composite resins on flat dentin surfaces, which were roughened with three different applications using different frequencies and modes of the Er:YAG laser. Materials and Methods: This study was performed on 32 third molar teeth. Teeth were randomly selected and divided into four groups, Er:YAG laser 1, Er:YAG laser 2, Er:YAG laser 3 and control group. Futurabond SingleDose VOCO adhesive system was used in all groups. Each gruop was divided into two sub-groups based on composite types (X-tra Fill VOCO, Grandio VOCO). 6 rods were obtained from the center of each tooth. µTBS test was applied to all samples and data was collected. Statistical analysis was performed in Sigmaplot 14 software. Results: There was no statistically significant difference between the median values of the groups (p=0,0964). The highest bonding value was seen in the control group without Er:YAG laser application. Conclusions: Er: YAG laser application did not increase the bond strength to dentin; it has been observed that bonding strengths of bulk fill and conventional composites are similar.

Performance of a Universal Bonding System Associated With 2% Digluconate Chlorhexidine in Carious and Eroded Dentin.

Carious and eroded dentin represent clinical challenges. The use of a universal bonding system, in a self-etching mode, associated with chlorhexidine (CHX) seems to not improve its longevity. This may be attributed to the competition for calcium between the bonding agent functional monomer and CHX.

Fatigue failure and success rate of lithium disilicate table-tops as a function of cement thickness.

Purpose Under thin, partial coverage restoration the proper cement thickness to be clinically employed still remains an issue. The aim of this study was to determine the failure and success rates of simplified lithium disilicate occlusal veneers as a function of cement thickness. The null hypothesis was that cement thickness has no effect on the fatigue resistance.Methods Sound human molars were severed in a plane parallel to the occlusal surface to create a flat dentin surface surrounded by enamel edges. Forty-five occlusal veneers 1.0 mm thick (IPS e.max CAD LT) were luted to the teeth with Multilink Automix resin cement, creating 3 experimental groups (n=15) with cement thicknesses of 50, 100, and 200 µm. The restorations were fatigue-cycled using a ball mill machine containing zirconia and stainless steel spheres. Twelve 60 min cycles were performed. Survival statistics were applied to "failure" and "success" events, comparing the three groups using a log-rank Mantel-Cox test and a log-rank test for trends (alpha = 0.05).Results The failure and success rates were not significantly influenced by cement thickness (P = 0.137 and P = 0.872, respectively); thus, the null hypothesis was accepted. However, when log-rank test for trends was applied to failure events, the tendency to have less failures with increasing thicknesses was found statistically significant (P = 0.047).Conclusions The cement thickness within the range adopted here did not have a significant effect on the failure or success rate of lithium disilicate occlusal veneers when exposed to randomized impact stresses generating fatigue phenomena.

The effect of 10% alpha-tocopherol solution and 5% grape seed extract on the microhardness and shear bond strength to bleached dentin

The aim of the study was to evaluate the effect of 10% alpha-tocopherol and 5% grape seed extract on the microhardness and shear bond strength (SBS) to bleached human dentin. This in vitro study was done on 200 extracted premolars which were decoronated and grinded to get flat dentin surface occlusaly. They were divided into four groups: (a) bleaching, (b) bleaching and application of alpha-tocopherol, (c) bleaching and application of grape seed extract, and (d) control. Groups were further subdivided into Subgroups I and II (n = 30) based on storage period before building with composite and were then tested for microhardness and SBS determination. The data thus obtained was subjected to statistical analysis which was performed using ANOVA test and post hoc Tukey's test. The significance for the entire statistical test was predetermined at P < 0.05. The results showed that the microhardness values were minimum in Group A (immediately after bleaching) and maximum in control group. Comparison of data using one-way ANOVA showed that the P value was highly significant (P < 0.001) among the groups. The intergroup comparison of SBS using post hoc Tukey's tests revealed that the P value was significant (P < 0.05) when the comparison was done between the Group A and Group C and Group B with Group D immediately after bleaching. Adverse effects of bleaching can be reversed with the application of 10% alpha-tocopherol and 5% grape seed extract over the dentinal surface microhardness and SBS.

Microtensile Bond Strength, Marginal Leakage, and Antibacterial Effect of Bulk Fill Resin Composite with Alkaline Fillers versus Incremental Nanohybrid Composite Resin.

Objective This study aimed to investigate the microtensile bond strength (µTBS), microleakage, and antibacterial effect of bulk fill resin composite with alkaline fillers (alkasite) (alkaline fillers such as barium aluminum silicate glass and ytterbium trifluoride) in comparison to incremental nanohybrid resin composite. Materials and Methods µTBS was evaluated by using 30 human mandibular molars. Teeth were randomly divided into three groups (C): nanohybrid resin composite (C0), self-cured alkasite (C1), and dual-cured alkasite (C2). Each group was subdivided into two subgroups according to the bulk thickness: 4 mm (T1) and 6 mm (T2). The occlusal enamel of teeth was removed and the resin composite was applied to a flat dentin surface. Then, teeth were sectioned into beams to be tested under tension. For microleakage testing, mesio-occlusal class II cavities were prepared in 15 molars and divided into three groups as mentioned before. Following this, cavities were restored, thermocycled, immersed in a dye, sectioned mesiodistally, and then dye penetration was assessed. The antibacterial effect of both tested materials was evaluated using agar disc diffusion and broth dilution methods against chlorhexidine as a control positive group. Results There was no significant difference in µTBS between all tested groups. Bulk fill self-cured alkasite showed the lowest microleakage value followed by bulk fill dual-cured alkasite and incremental nanohybrid resin composite, respectively. Also, cervical microleakage showed significantly higher mean value than the occlusal one. The antibacterial effect of alkasite was less than chlorhexidine. Alkasite showed maximum broth clarity at lowest tested bacterial concentration. Conclusion Resin composite with alkaline fillers was characterized by good µTBS and marginal integrity with weak antibacterial effect.

Influence of etching mode and composite resin type on bond strength to dentin using universal adhesive system.

Adhesive bond strength at the composite/dentin interface is influenced by various factors, including the etching mode and composite resin type. The purpose of this study was to evaluate the influence of the total-etch and self-etch mode on the microtensile bond strength (μTBS) of conventional and bulk-fill composite to dentin, using the universal adhesive system. Sixty non-carious human teeth were sectioned parallel to their longitudinal axis, using a low-speed diamond saw to obtain a flat dentin surface. According to the etching technique and composite resin type used, teeth were randomly divided into four different groups (n=15): TC (total-etch/conventional composite), TB (total-etch/bulk-fill composite), SC (self-etch/conventional composite), and SB (self-etch/bulk-fill composite). Cylindric composite build-ups were made with 3M Filtek Z250 and 3M Filtek Bulkfill Posterior, using a plastic mold, 4 mm in diameter and 4 mm in height. The specimens were subjected to the μTBS test in a universal testing machine and failure force was recorded. Failure modes were determined using stereoscopic and scanning electron microscopy. Data were analyzed using the two-way ANOVA and Student's t test. The μTBS was significantly affected by the etching technique. A significant statistical difference was determined between total-etch and self-etch groups, irrespective of the composite resin type used. Higher bond strength was obtained in total-etch groups. The μTBS was not affected by the composite resin type. No significant statistical difference was determined between the conventional and bulk-fill groups, irrespective of the etching-mode.

The effect of proanthocyanidin and casein phosphopeptide-amorphous calcium phosphate on the bond strength durability to caries-affected dentin.

ObjectivesThe aim of this study was to evaluate the effect of proanthocyanidin (PA) and casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP) paste on the micro‐shear bond strength (μSBS) durability of an etch‐and‐rinse adhesive to caries‐affected dentin (CAD).Materials and methodsThe occlusal surfaces of 80 human molars with occlusal caries were ground to expose flat dentin surfaces with CAD. Then, they were randomly divided into four groups (n = 20) according to the CAD pretreatment. The study groups included no pretreatment, pretreatment with CPP‐ACP for 3 min, pretreatment with PA for 1 min, and pretreatment with PA for 1 min followed by CPP‐ACP for 3 min before adhesive application. After restoring the specimens with composite resin, μSBS testing was performed for half of the bonded surfaces in each group after 24 h and the other half was tested after 6 months of water storage and failure mode analysis was performed.ResultsThe PA group was associated with a higher μSBS than the control and CPP‐ACP groups after 24 hours (p < 0.05). No significant difference was observed regarding the μSBS of the control and the other groups after 24 h (p > 0.05). No significant difference was observed regarding the μSBS of the PA and PA + CPP‐ACP groups (p > 0.05). The μSBS of the 6‐month specimens was significantly lower than those of the 24‐h specimens for all the groups (p < 0.05) except for the PA group which did not exhibit a significant difference between the two times (p > 0.05). The most common type of failure was mixed failure.ConclusionPA pretreatment could stabilize the CAD‐resin interface and protect degradation over time. The same effect was not observed for CPP‐ACP or PA + CPP‐ACP.