Dentin Surface Treatment Research Articles

Micromorphology and bond strength evaluation of adhesive interface of a self-adhering flowable composite resin-dentin: Effect of surface treatment.

This study evaluated the effect of dentin surface treatment on the micromorphology and shear bond strength (SBS) of a self-adhering flowable composite, Vertis Flow (VF). Flat dentin surfaces obtained from sixty extracted human molars were divided into six groups (n = 10) according to the following surface treatments: (G1) control, no treatment; (G2) self-etching adhesive, Optibond All-in-One; (G3) phosphoric acid etching for 15 s; (G4) polyacrylic acid for 10 s; (G5) EDTA for 60 s; and G6) sodium hypochlorite (NaOCl) for 15 s. After restoration using VF, SBS was measured in MPa. Data were analyzed using one-way ANOVA and Tamhane test (α = 0.05). Six additional specimens were prepared for scanning electron microscopy analysis. SBS was significantly affected by surface treatment (P < 0.001). SBS of six groups from the highest to the lowest were as follows: (G3) 13.5(A); (G5) 8.98(AB); (G2) 8.85(AB); (G4) 8.21(AB); (G1) 7.53(BC); and (G6) 4.49(C) (groups with the same superscript letter were statistically similar). Morphological analysis revealed numerous long resin tags at the adhesive interface for acid-etched group, with a few short resin tags for the control group and small gap formation for NaOCl-treated group. In conclusion, dentin surface treatments tested differently affected bonding performance of VF; only acid-etching effectively improved this.

Effect of HEMA Phosphate as an Alternative to Phosphoric Acid for Dentin Treatment Prior to Hybridization with Etch-and-Rinse Adhesive Systems.

To evaluate the effect of dentin treatment using HEMA phosphate (HEMA-P) on the microtensile bond strength (μTBS) and nanoleakage of an etch-and-rinse adhesive system. The occlusal surfaces of human molars were wet ground until superficial dentin was exposed. The specimens were then assigned to two groups according to dentin treatment: PA: 37% H₃PO₄ for 15 s; or HP: HEMA-P for 15 s. Adper Single Bond 2 was applied to the treated dentin surfaces and resin composite buildups were incrementally constructed over them. After 24-h storage in artificial saliva at 37°C, the bonded teeth were cut into resin-dentin sticks with a cross-sectional area of 1 mm², which were submitted to μTBS testing immediately or after 3 months of storage in artificial saliva at 37°C. Nanoleakage was assessed using SEM/EDS, and the interaction between dentin and H₃PO₄ or HEMA-P was evaluated by combining micro-Raman and FT-IR spectroscopy. The data were analyzed using two-way ANOVA and Tukey's HSD post-hoc test (α = 0.05). HP presented significantly higher μTBS than PA at both times (p < 0.05). Both treatments maintained μTBS stability after 3 months of artificial saliva storage (p > 0.005). At both times, PA presented higher nanoleakage than HP (p < 0.05). Both dentin treatments maintained μTBS stability after 3 months of artificial saliva storage. The use of HEMA-P was associated with less nanoleakage than was traditional phosphoric-acid etching.

Evaluation of microshear bond strength and nanoleakage of etch-and-rinse and self-etch adhesives to dentin pretreated with silver diamine fluoride/potassium iodide: An in vitro study.

The aim of this in vitro study was to comparatively evaluate the microshear bond strength (MSBS) of etch-and-rinse and self-etch (ER and SE) bonding systems to dentin pretreated with silver diamine fluoride/potassium iodide (SDF/KI) and nanoleakage at the resin-dentin interface using transmission electron microscope (TEM). Seventy-two dentin slabs of 3 mm thickness were prepared from extracted human permanent third molars and divided into four groups (n = 18) based on the dentin surface treatment as follows: (1) ER adhesive bonding without dentin pretreatment; (2) SDF/KI pretreatment of dentin followed by ER adhesive bonding; (3) SE adhesive bonding without dentin pretreatment; and (4) SDF/KI pretreatment of dentin followed by SE adhesive bonding. Resin composite was built on the dentin slabs to a height of 4 mm incrementally, and dentin-composite beams of approximately 1 mm 2 cross-sectional area were prepared. The beams were subjected to MSBS analysis, and the fractured surface was observed under scanning electron microscope to determine the mode of failure. The resin-dentin interface was examined under TEM for evaluation of nanoleakage. One-way ANOVA followed by Tukey's post hoc multiple comparison tests. Pretreatment of dentin with SDF/KI increased the MSBS of ER and SE adhesives, though not statistically significant, except between Groups 2 and 3. In all the groups, the predominant mode of failure was adhesive followed by cohesive in resin, mixed and cohesive in dentin. TEM examination of resin-dentin interface showed that pretreatment with 38% SDF/KI reduced nanoleakage regardless of the type of bonding system used. Pretreatment of dentin with SDF/KI minimized nanoleakage at the resin-dentin interface without adversely affecting the bond strength of resin composite to dentin.

Effect of timing of dentin sealing and provisional restoration method on bond strength of composite resin to dentin

The purpose of this study was to evaluate the effect of timing of dentin sealing and provisional restoration methods on the bond strength of composite resin to dentin. Flat dentin surfaces were prepared and the teeth were divided into three groups: control, resinrestoration with immediate dentin sealing (IDS), and resin restoration with delayed dentin sealing (DDS). For the control group, a dentin surface was bonded by using dual-curing dentin adhesive (Excite DSC) and restored with resin immediately. For the IDS groups, a dentin was sealed with OptiBond FL (OB) or Hybrid Coat (HC), and it was restored with following 3 provisional restoration methods: SQ/PQ/CQ {SQ, water-soluble separator (SEP) + provisional resin; PQ, petroleum jelly + provisional resin; CQ, temporary cement (Cavitec) + provisional resin}. For the DDS groups, a dentin was temporized with 2 provisional restoration methods: Q/CQ (Q, provisional resin only) without dentin sealing. After a week, the provisional restoration was removed and cleaned. The treated dentin surface was bonded using Excite DSC and restored with resin, followed by microtensile bond strength (μTBS) tests. The μTBS of control and the IDS-OB groups were not significantly different (P>0.05). The DDS groups presented lower μTBS than control and the IDS-OB groups (P 0.05). However, using CQ significantly lower the μTBS than using Q in the DDS groups (P<0.05). IDS with a etch-and-rinse type dentin bonding agent improved the bond strength. The use of ZOE-containing cement on the unsealed dentin surface decreased the μTBS.

Influence of different etching modes on bond strength and fatigue strength to dentin using universal adhesive systems

ObjectivesThe purpose of this study was to determine the dentin bonding ability of three new universal adhesive systems under different etching modes using fatigue testing. MethodPrime & Bond elect [PE] (DENTSPLY Caulk), Scotchbond Universal [SU] (3M ESPE), and All Bond Universal [AU] (Bisco) were used in this study. A conventional single-step self-etch adhesive, Clearfil Bond SE ONE [CS] (Kuraray Noritake Dental) was also included as a control. Shear bond strengths (SBS) and shear fatigue strength (SFS) to human dentin were obtained in the total-etch mode and self-etch modes. For each test condition, 15 specimens were prepared for the SBS and 30 specimens for SFS. SEM was used to examine representative de-bonded specimens, treated dentin surfaces and the resin/dentin interface for each test condition. ResultsAmong the universal adhesives, PE in total-etch mode showed significantly higher SBS and SFS values than in self-etch mode. SU and AU did not show any significant difference in SBS and SFS between the total-etch mode and self-etch mode. However, the single-step self-etch adhesive CS showed significantly lower SBS and SFS values in the etch-and-rinse mode when compared to the self-etch mode. Examining the ratio of SFS/SBS, for PE and AU, the etch-and-rinse mode groups showed higher ratios than the self-etch mode groups. SignificanceThe influence of different etching modes on dentin bond quality of universal adhesives was dependent on the adhesive material. However, for the universal adhesives, using the total-etch mode did not have a negative impact on dentin bond quality.

Regenerative potential of immature permanent non-vital teeth following different dentin surface treatments

This study evaluates the regenerative potential of immature permanent non-vital teeth following different dentin surface treatments in dogs. Periapical lesions and necrotic pulps were induced in 288 roots of 144 teeth in twelve dogs. Teeth were randomly divided into 3 equal groups according to the evaluation period. Each group was subdivided into 8 subgroups according to the treatment modalities including; blood clot, blood clot and collagen, blood clot and Ethylenediaminetetraacetic acid (EDTA), blood clot, collagen and EDTA, blood clot and Mixture Tetracycline Citric Acid and Detergent (MTAD), blood clot, collagen and MTAD, positive control and negative control. Apart from control subgroups, all infected root canals were cleaned with sodium hypochlorite solution and triple antibiotics paste before different treatment protocols. After different treatments, the root length, thickness and apical diameter were evaluated by radiographic examination. Histopathological examination was carried out to evaluate the inflammation, bone/root resorption, tissue in-growth in pulp space, new hard tissue formation and apical closure. Using EDTA solution as a surface modifier showed significantly higher levels of tissue in-growth in the pulp space after 6 weeks and 3 months. Addition of collagen as a scaffold caused significantly more bone/root resorption than the other subgroups while EDTA caused significantly lower inflammatory cell counts only after 2 weeks. Final rinse with 17% EDTA solution before blood clot induction has positive impact on tissue interaction along dentinal walls without modification of the cell type. Moreover, the use of collagen as a scaffold material and MTAD as a surface modifier did not improve the quality of the regenerative process.

Bond Strength of Resin Composite to Dentin with Different Adhesive Systems: Influence of Relative Humidity and Application Time.

To investigate the influence of relative humidity and application time on bond strength to dentin of different classes of adhesive systems. A total of 360 extracted human molars were ground to mid-coronal dentin. The dentin specimens were treated with one of six adhesive systems (Syntac Classic, OptiBond FL, Clearfil SE Bond, AdheSE, Xeno Select, or Scotchbond Universal), and resin composite (Filtek Z250) was applied to the treated dentin surface under four experimental conditions (45% relative humidity/application time according to manufacturers' instructions; 45% relative humidity/reduced application time; 85% relative humidity/application time according to manufacturers' instructions; 85% relative humidity/reduced application time). After storage (37°C, 100% humidity, 24 h), shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by Kruskal-Wallis tests and Mann-Whitney U-tests with Bonferroni-Holm correction for multiple testing (level of significance: α = 0.05). Increased relative humidity and reduced application time had no effect on SBS for Clearfil SE Bond and Scotchbond Universal (p = 1.00). For Syntac Classic, OptiBond FL, AdheSE, and Xeno Select there was no effect on SBS of reduced application time of the adhesive system (p ≥ 0.403). However, increased relative humidity significantly reduced SBS for Syntac Classic, OptiBond FL, and Xeno Select irrespective of application time (p ≤ 0.003), whereas for AdheSE, increased relative humidity significantly reduced SBS at recommended application time only (p = 0.002). Generally, increased relative humidity had a detrimental effect on SBS to dentin, but reduced application time had no effect.

Plasma treatment of dentin surfaces for improving self-etching adhesive/dentin interface bonding

This study is to evaluate plasma treatment effects on dentin surfaces for improving self-etching adhesive and dentin interface bonding. Extracted unerupted human third molars were used after crown removal to expose dentin. One half of each dentin surface was treated with atmospheric non-thermal argon plasmas, while another half was untreated and used as the same tooth control. Self-etching adhesive and universal resin composite was applied to the dentin surfaces as directed. After restoration, the adhesive–dentin bonding strength was evaluated by micro-tensile bonding strength (μTBS) test. Bonding strength data was analyzed using histograms and Welch׳s t-test based on unequal variances. μTBS test results showed that, with plasma treatment, the average μTBS value increased to 69.7±11.5MPa as compared with the 57.1±17.5MPa obtained from the untreated controls. After 2 months immersion of the restored teeth in 37°C phosphate buffered saline (PBS), the adhesive–dentin bonding strengths of the plasma-treated specimens slightly decreased from 69.7±11.5MPa to 63.9±14.4MPa, while the strengths of the untreated specimens reduced from 57.1±17.5MPa to 48.9±14.6MPa. Water contact angle measurement and scanning electron microscopy (SEM) examination verified that plasma treatment followed by water rewetting could partially open dentin tubules, which could enhance adhesive penetration to form thicker hybrid layer and longer resin tags and consequently improve the adhesive/dentin interface quality.

Evaluation of Effects on the Adhesion of Various Root Canal Sealers after Er:YAG Laser and Irrigants Are Used on the Dentin Surface

IntroductionThe aim of this study was to evaluate the bond strength of various root canal sealers after various irrigation solutions and Er:YAG laser irradiation were used on root canal dentin. MethodsOne hundred fifty freshly extracted human maxillary single-rooted teeth were used in this study. Teeth were sectioned transversally 4 mm below the cementoenamel junction. The root canal of each specimen was prepared using a tapered bur. Teeth were divided into 3 main groups by sealer (AH Plus Jet [Dentsply DeTrey, Konstanz, Germany], EndoSequence BC Sealer [Brasseler, Savannah, GA], and Real Seal [SybronEndo, Orange, CA]) and then divided into 5 subgroups by dentin treatment (distilled water, calcium hydroxide, sodium hypochlorite, EDTA, and Er:YAG laser). The specimens were placed immediately at 37°C and 100% humidity for 1 week. Then, the push-out test was applied. The maximum failure load was recorded in newtons and was used to calculate the push-out bond strength in MPa. Then, 3 random specimens from each group were examined under scanning electron microscopy. ResultsThe resin root canal sealers had higher push-out bond strength than the bioceramic sealer, and the differences were statistically significant (P < .05) except in the sodium hypochlorite groups. The EDTA and Er:YAG laser applications removed the smear layer and increased the bond strength. The highest adhesion was observed in EDTA groups when each sealer was evaluated in itself. ConclusionsThe bonding strength of root canal sealers is influenced by their properties and various dentin surface treatments. The scanning electron microscopic study showed that although the dentinal tubules were open, at the profile examination the sealers did not penetrate into the dentin canals in all specimens.

Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers.

This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n = 168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz); diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p < 0.05). Both adaptation and sealer penetration in root canals were not affected by the laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p < 0.05). It can be concluded that intracanal laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

Evaluation of some intracanal irrigants on push-out bond strength and mode of failure of resin and non resin cements to root canal dentin (in vitro comparative study)

Objectives: The purpose of this study was to evaluate the effects of five intracanal irrigants [distilled water, NaOCl, NaOCl + EDTA, ozonated water and NaOCl + ozonated water] on push-out bond strength of (zinc phosphate cement and Calibra® esthetic resin cement) and to determine the mode of failure. Materials and Methods: Seventy extracted single straight rooted teeth were selected. The crowns were sectioned at cemento-enamel junction. The sectioned roots were embedded vertically in clear acrylic resin. The root canals were prepared with K-files and Gates Glidden drills using step-back technique then the specimens were randomly assigned to five main groups according to the types of irrigant used and each main group were divided in to two subgroups and filled with zinc phosphate cement and Calibra® esthetic resin cement. The samples were sectioned horizontally to provide 4 millimeter dentin disc from coronal third of the roots. Each sectioned specimen was tested by using computerized universal testing machine. Finally each de-bonded specimens was examined under stereomicroscope to determine the mode of failure. Results: Two-way ANOVA tests showed that there was statistical significance difference between the two type of cement used in this study, also there was statistical significance difference between the types of irrigant; while the interaction between types of cement with types of irrigant was not statistically significant. Considering the dentine surface treatment, Paired T-test showed that irrigation with 5.25% NaOCl produce statistically significant reduction in bond strength to root canal dentin in comparison to control group, while irrigation with distilled water, 5.25 NaOCl plus 17% EDTA, 5.25% NaOCl plus 5gm/L ozonated water, 5gm/L ozonated water alone had no statistical significant affect on bond strength to root canal dentin. Comparing the cements, zinc Phosphate cement showed higher bond strength in comparison to Calibra® esthetic resin cement. Conclusions: NaOCl have negative effect on bond strength to root canal dentin, while distilled water, NaOCl plus EDTA, ozonated water alone or after NaOCl had no effect. Zinc phosphate cement had higher bond strength than Calibra® esthetic resin cement. The adhesive and mixed failures were higher than the cohesive failure for all groups in general.

Impact of intracoronal dentin treatment prior to bleaching on bond strength of restorative materials.

Surface treatment of dentin before the bleaching procedure may affect its permeability and influence the bond strength of restorative materials. This study evaluated the influence of surface treatment before the bleaching on shear bond strength (SBT) of restorative materials to intracoronal dentin. Dentin slabs were subjected to surface treatment: no bleaching (control - CON), no surface treatment + bleaching (HP), 37% phosphoric acid + bleaching (PA) and Er:YAG laser + bleaching (L). After the bleaching procedure, specimens (n=10) were restored with: microhybrid composite resin (MH), flowable composite resin (F), and resin-modified glass-ionomer cement (RMGIC). The shear test was carried out. ANOVA and Tukey's test (α=0.05) showed significant difference for surface treatment and restorative materials (p<0.05). CON presented higher STB and was statistically different from HP (p<0.05). PA and L showed intermediate values and were statistically similar to CON and HP (p>0.05). STB for MH and F were higher than RMGIC (p<0.05), and did not differ from each other (p>0.05). The surface treatments with phosphoric acid and Er:YAG laser before the bleaching procedure provided shear bond strength at the same level of unbleached dentin and the composite resins presented superior bond strength to the intracoronal dentin.

Effects of dentin surface treatments including Er,Cr:YSGG laser irradiation with different intensities on the push-out bond strength of the glass fiber posts to root dentin

Objective. Intra-canal post systems are commonly used to restore root-filled teeth. Bond strengths of the posts can be affected by various surface treatments of the post or the dentin. The aim of this study was to evaluate the effects of dentin surface treatments including erbium-chromium; yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation with different intensities on the push-out bond strength of the glass fiber posts to root dentin. Materials and methods. Forty single-rooted human maxillary incisors were filled and post spaces were prepared. After these procedures, the specimens were divided randomly into four groups according to the dentin surface treatments, as follows: (i) untreated surface (control), (ii) 1W Er,Cr:YSGG laser application, (iii) 2W Er,Cr:YSGG laser application and (iv) 3W Er,Cr:YSGG laser application. Then the posts were cemented into the root canals using dual-cured resin cement. Bonded specimens were cut into 1-mm-thick slices and push-out tests were performed using a universal testing device. All specimens were loaded until fracture and the failure modes were evaluated with a stereomicroscope at 32× magnification. Representative specimens were analyzed by scanning electron microscopy. Data were analyzed using a one-way ANOVA, Tukey and Wilcoxon tests. Results. The bond strength values ranged from 3.22–4.68 MPa. There were no statistically significant differences among the groups, regardless of the different levels. The coronal and middle levels of the post space had significantly higher bond strength values compared with the apical level (p < 0.05). Conclusion. Er,Cr:YSGG laser irradiation with different intensities did not increase the bond strength of the fiber posts to the root canal dentin walls.

Effect of Two Matrix Metalloproteinase Inhibitors on the Color Stability of a Nanofilled Resin Composite

This in vitro study evaluated the effect of two matrix metalloproteinase (MMP) inhibitors on the color stability of two shades of a nanofilled resin composite. A total of 60 sound human molars were used in this study. Flat dentin surfaces were obtained by wet grinding the occlusal surfaces. Following acid etching, the molars were divided into three equal groups according to the MMP inhibitor used: Group 1: no inhibitor (control group), group 2: chlorhexidine digluconate based (CHX; Consepsis, Ultradent, South Jordan, UT, USA); group 3: doxycycline based (MTAD; Biopure, Dentsply TulsaDental, Johnson, TN, USA). Adper Single Bond 2 Adhesive (3M ESPE, St Paul, MN, USA) was applied to the treated dentin surfaces. Each group was then subdivided into two equal subgroups of 10 molars each, according to the shade of the resin composite (Filtek Z350 XT, 3M ESPE) used, either B1 or A3. The color was assessed for each subgroup at three times: baseline (after 24 hours); after aging using a total energy of 600 kJ/m(2) (Weather-Ometer Ci35A, Atlas Electronic Devices Company, Chicago, IL, USA); and then after a second period of aging, for a total energy of 1200 kJ/m(2). Color assessment was carried out using a spectrophotometer. Color change (ΔE) was calculated according to the Commission Internationale de l'Eclairage L*a* b* color scale, comparing each aging period with the baseline color measurement. Data were analyzed using repeated measures analysis of variance and Tukey post hoc test. All tested subgroups showed greater discoloration than the clinically acceptable level (3.3). MTAD induced the highest statistically significant color change, followed by CHX, whereas the control groups showed the lowest statistical ΔE values with both tested shades. Shade B1 subgroups showed higher ΔE values when compared with shade A3 subgroups. Accelerated aging caused color change in a nanofilled resin composite regardless of MMP inhibitor used. Furthermore, lighter shades showed less color stability when compared with darker shades.

Effect of dentine conditioning on adhesion of resin-modified glass ionomer adhesives.

The aim of this study was to investigate the use of phosphoric acid as a surface treatment compared to traditional conditioning agents to dentine bonded with resin-modified glass ionomer (RMGIC) adhesives. Forty human molars were utilized in microtensile bond strength testing, while another 16 were used for evaluation of the bonded interface with scanning electron microscopy. Three RMGIC adhesives were evaluated: Fuji Bond LC (GC Corp); Riva Bond LC (SDI Ltd); and Ketac N100 (3M-ESPE). Surface treatments were 37% phosphoric acid (5 s) or 25-30% polyacrylic acid (PAA) (10 s), or the manufacturer's method - Fuji Bond LC: Cavity Conditioner (20% PAA+3% AlCl3 10 s) or Ketac N100 primer: Ketac Nano priming agent (15 s). Teeth were finished with 600-grit SiC paper, surfaces treated and bonded with RMGIC adhesive and stored in distilled water for 24 h then subjected to microtensile bond strength testing. Two-way analysis of variance (ANOVA) revealed adhesion was affected by the 'type of RMGIC adhesive' and 'method of dentine surface treatment' (p < 0.05). The microtensile bond strength of Ketac N100 primer groups was lower than Fuji Bond LC and Riva Bond LC (p < 0.05). For RMGIC adhesives a brief etch with phosphoric acid does not adversely effect short-term bond strengths, but is no better than traditional conditioning with PAA.

Effect of different surface treatments on the shear and microtensile bond strength of resin-modified glass ionomer cement to dentin

Objective. The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) and shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) to dentin. Materials and methods. Fifty-two extracted human molars were flattened to obtain dentin surfaces. For SBS assessment 40 teeth were divided into four groups according to their surface treatments (acid etching, Er:YAG laser QSP mode, Er:YAG laser MSP mode and control-SiC) (n = 10). A plastic cylinder was placed over the differently treated dentin surfaces and RMGIC was placed into the rings and polymerized. Twelve teeth were used for the μTBS test. The treated dentin surfaces described above were restored with 4 mm high RMGIC and light cured; then, the specimens were sectioned into serial sticks (n = 15) and μTBS and SBS were tested for failure in a testing machine with a 1 mm/min crosshead speed. The data were analyzed by one-way ANOVA and Tukey HSD tests (α = 0.05). Results. Acid etching showed significantly higher SBS than the other groups (p < 0.05). Er:YAG QSP and MSP-treated groups showed higher SBS values than the control group, but the difference was not statistically significant (p > 0.05). Er:YAG MSP showed the highest μTBS value followed by acid etching, whereas the control group exhibited the lowest value (p < 0.05) and the differences between the control group and Er:YAG QSP were not significant (p > 0.05). Conclusions. The application of Er:YAG MSP mode and acid etching to dentin can be used for improving the bond strength of RMGIC.

A mechanistic study of plasma treatment effects on demineralized dentin surfaces for improved adhesive/dentin interface bonding

Our previous work has shown that non-thermal plasma treatment of demineralized dentin significantly (p<0.05) improved adhesive/dentin bonding strength for dental composite restoration as compared with the untreated controls. This study is to achieve mechanistic understanding of the plasma treatment effects on dentin surface through investigating the plasma treated dentin surfaces and their interaction with adhesive monomer, 2-hydroxyethyl methacrylate (HEMA). The plasma treated dentin surfaces from human third molars were evaluated by water contact angle measurements and scanning electron microscopy (SEM). It was found that plasma-treated dentin surface with subsequent HEMA immersion (Plasma/HEMA Treated) had much lower water contact angle compared with only plasma-treated (Plasma Treated) or only HEMA immersed (HEMA Treated) dentin surfaces. With prolong water droplet deposition time, water droplets spread out completely on the Plasma/HEMA Treated dentin surfaces. SEM images of Plasma/HEMA Treated dentin surfaces verified that dentin tubules were opened-up and filled with HEMA monomers. Extracted type I collagen fibrils, which was used as simulation of the exposed dentinal collagen fibrils after acid etching step, were plasma treated and analyzed with Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) spectra. FT-IR spectra of the Plasma/HEMA Treated collage fibrils showed broadened amide I peak at 1660cm−1 and amide II at 1550cm−1, which indicate secondary structure changes of the collagen fibrils. CD spectra indicated that 67.4% collagen helix structures were denatured after plasma treatment. These experimental results demonstrate that non-thermal argon plasma treatment was very effective in loosing collagen structure and enhancing adhesive monomer penetration, which are beneficial to thicker hybrid layer and longer resin tag formation, and consequently enhance adhesive/dentin interface bonding.

The Evaluation of the Effects of Different Irrigating Solutions and Laser Systems on Adhesion of Resin-Based Root Canal Sealers

The purpose of this study was to evaluate the effects of different laser systems and different irrigating solutions on the adhesion of AH Plus and EndoREZ root canal sealers to human root canal dentin. Laser irradiation can be used to obtain morphological changes in dentin walls that could influence the adhesion values of endodontic sealers. One hundred canine root canals were cleaned and shaped. The specimens were assigned to four groups (n=24). In group I 5% NaOCl (control), in group II 15% ethylenediaminetetraacetic acid (EDTA) followed by 5% NaOCl, in group III Er:YAG laser with 2940 nm wavelength, and in group IV Nd:YAG laser with 1064 nm were used as a final procedure in root canals. In each group, half of the specimens were filled with AH Plus sealer and half with EndoREZ with gutta-percha, using cold lateral compaction. Specimens were sectioned to obtain three slices from each third using a precission saw. The first slice of 1 mm thick dentin disks from each third was subjected to the pushout test (MPa). Results were analyzed by analysis of variance (ANOVA) and Tukey's test (p<0.05). A statistically significant difference (p<0.05) was reported between dentin surface treatments (Er:YAG and control groups). Control (1.60±0.99), EDTA (2.05±1.35), Er:YAG (2.25±1.64), and Nd:YAG (2.13±1.38). AH Plus adhesion values were increased significantly (p<0.05) when the root canal was irradiated with the Er:YAG laser. Nd:YAG laser irradiation increased EndoREZ adhesion values significantly when compared with Er:YAG laser irradiation (p<0.05). In the apical and coronal thirds, AH Plus showed better adhesion than did EndoREZ sealer (p<0.005). In the middle third, there was no statistical difference between AH Plus and EndoREZ. The use of EDTA and different laser systems influenced the bond strength of resin-based root canal sealers.

Marginal adaptation of class V restorations with current-generation dentin-bonding agents: effect of different dentin surface treatments.

This study sought to assess the use of chlorhexidine with several excipients as a dentin surface treatment and its effect on marginal adaptation of class V restorations with current-generation dentin bonding agents. A total of 120 human third molars were selected and allocated into 12 groups, with standardized buccal class V restorations randomly divided into preconditioned dentin rinsed with: water; water + chlorhexidine; ethanol; or ethanol + chlorhexidine. After rinsing of dentin (previously conditioned with 35% phosphoric acid) with the test solutions, the Adper single bond 2, prime and bond 2.1, and Excite bonding systems were applied randomly. Restorations were performed with Filtek™ Z350 XT composite resin. The resulting specimens were subjected to thermal and mechanical load cycling. Quantitative analysis of marginal adaptation was performed on epoxy replicas by means of scanning electron microscopy. Results were assessed by means of the Kruskal-Wallis test (percentages of continuous margins) and Wilcoxon test (differences between percentages of continuous margins before and after thermal cycling and mechanical loading), at a significance level of p < 0.05. Outcomes in the chlorhexidine-treated groups were not superior to those obtained with other treatments.

The effect of different disinfecting agents on bond strength of resin composites.

Objective. The aim of this study was to evaluate the effect of different disinfectant agents on bond strength of two types of resin composite materials. Methods. A total of 80 sound posterior teeth were used. They were divided into four groups (n = 20) according to the dentin surface pretreatment (no treatment, chlorhexidine gluconate 2%, sodium hypochlorite 4%, and EDTA 19%). Each group was divided into two subgroups according to the type of adhesive (prime and bond 2.1 and Adper easy one). Each subgroup was further divided into two subgroups according to the type of resin composite (TPH spectrum and Tetric EvoCeram). Shear bond strength between dentin and resin composite was measured using Universal Testing Machine. Data collected were statistically analyzed by t-test and one-way ANOVA followed by Tukey's post hoc test. Results. It was found that dentin treated with EDTA recorded the highest shear bond strength values followed by sodium hypochlorite and then chlorhexidine groups while the control group showed the lowest shear bond strength. Conclusions. The surface treatment of dentin before bonding application has a great effect on shear bond strength between resin composite and dentin surface.