Shear bond strength of acetone-based one-bottle adhesive systems

The aim of this study was to assess the shear bond strength of four acetone-based one-bottle adhesive systems to enamel and dentin, and compare to that of an ethanol-based system used as control. Fifty human molars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin using PVC cylinders. The buccal surfaces were ground to obtain flat dentin surfaces, while the lingual surfaces were ground to obtain flat enamel surfaces. All specimens were polished up to 600-grit sandpapers and randomly assigned to 5 groups (n=20; 10 dentin specimens and 10 enamel specimens), according to the adhesive system used: One-Step (Bisco); Gluma One Bond (Heraeus Kulzer); Solobond M (Voco); TenureQuik w/F (Den-Mat) and OptiBond Solo Plus (Kerr) (control). Each adhesive system was applied according to the manufacturers' instructions. The respective proprietary hybrid composite was applied in a gelatin capsule (d=4.3 mm) and light-cured for 40 s. The specimens were tested in shear strength with an Instron machine at a crosshead speed of 5 mm/min. Bond strengths means were analyzed statistically by one-way ANOVA and Duncan's post-hoc (p< or =0.05). Shear bond strength means (MPa) (+/-SD) to enamel and dentin were: Enamel: One-Step=11.3(+/-4.9); Gluma One Bond=16.3(+/-10.1); Solobond M=18.9(+/-4.5); TenureQuik w/F=18.7(+/-4.5) and OptiBond Solo Plus=16.4(+/-3.9); Dentin: One-Step=6.4(+/-2.8); Gluma One Bond=3.0(+/-3.4); Solobond M=10.6(+/-4.9); TenureQuik w/F=7.8(+/-3.9) and OptiBond Solo Plus=15.1(+/-8.9). In enamel, the adhesive systems had statistically similar bond strengths to each other (p>0.05). However, the ethanol-based system (OptiBond Solo Plus) showed significantly higher bond strength to dentin than the acetone-based systems (p< or =0.0001). In conclusion, the solvent type (acetone or ethanol) had no influence on enamel bond strength, but had great influence on dentin bonding, which should be taken into account when choosing the adhesive system.     

Bond strength of adhesives to dentin involving total and self-etch adhesives.

OBJECTIVE: Currently, the trend in dentin adhesion seems to be shifting from moist bonding systems to self-etching systems and from several application steps to single steps. However, recent studies have indicated that the performance of single-step adhesives was lower than the 2-step self-etch or total etch systems. In the present study, microtensile bond strength of a total etch, 2-step self-etch and single-step self-etch adhesives was comparatively evaluated. METHOD AND MATERIALS: The superficial occlusal dentin of 12 noncarious extracted human molars was exposed, finished with wet 600-grit silicon carbide paper, and a block of resin composite bonded with adhesives according to the manufacturers' instructions. The teeth were kept in tap water for 24 hours at 37 degrees C and sectioned to produce beams, with adhesive areas of +/- 0.9 mm2 (4 beams per tooth were obtained). The specimens were stressed at a crosshead speed of 1 mm per minute until the bonds ruptured. RESULTS: The mean bond strengths were calculated as MPa and compared by performing analysis of variance and Tukey tests to identify significant differences between the materials (P = 0.05). The mean bond strength of Clearfil SE Bond was significantly higher than that of OptiBond Solo Plus and iBond (P <.05). OptiBond Solo Plus gave significantly higher bond strengths than iBond (P <.05). CONCLUSIONS: The self-etching adhesive system Clearfil SE Bond (2 step) had higher bond strength than the 1-bottle self-etching adhesive iBond (single application) and the 2-step single-bottle system OptiBond Solo Plus (total etch). However, the 1-bottle adhesive system OptiBond Solo Plus (total etch system) had higher bond strength than the 1-bottle self-etching adhesive system iBond.     

MTAD根管冲洗液对牙本质、牙釉质微硬度影响的研究

目的:评价MTAD根管冲洗液对牙本质、牙釉质微硬度的影响。方法:收集新鲜完整的前磨牙48个,截取牙冠并沿牙体长轴剖开,分别用30mL/L过氧化氢液、50g/L次氯酸钠液、MTAD液、13g/L次氯酸钠液处理牙本质、牙釉质5、15min,采用微硬度测定仪测定处理前、后两个时间点上牙本质、牙釉质的微硬度。结果:与30mL/L过氧化氢液和50g/L次氯酸钠液相比,使用MTAD液和13g/L次氯酸钠液处理后的牙本质、牙釉质微硬度的降低幅度不明显。结论:通过与30mL/L过氧化氢液、50g/L次氯酸钠液的对比研究发现,MTAD冲洗液对牙本质、牙釉质微硬度的影响明显小于前两者, 13g/L次氯酸钠冲洗液的影响与MTAD的相似,MTAD液联合13g/L次氯酸钠液的根管冲洗方法值得推荐。     

Bond strength of two total-etching bonding systems on caries-affected and sound primary teeth dentin

AIM: As bond strength of currently available adhesive systems in caries-affected teeth dentin on primary tooth dentin was not well known, the bond strength of two bonding systems (PQI and OptiBond Solo Plus) was evaluated on caries-affected and sound primary molar tooth dentin and observed the micromorphology of the adhesive-dentin interfaces. METHODS: By grinding both the sound (n = 30) and caries-affected (n = 30) approximal surfaces of teeth, flat dentin surfaces were obtained. The prepared surfaces were bonded with one of the each adhesive systems and a composite resin. After storing the bonded specimens in water at 37 degrees C for 24 h, the samples were sectioned and the bond strength of the adhesive systems was tested by the microshear test method. The data were statistically analysed. RESULTS: Microshear bond strengths of PQI group for caries-affected and sound primary tooth dentin were 9.43 +/- 2.44 (MPa) and 9.32 +/- 2.95 (MPa) (P > 0.05), respectively, and the bond strengths of OptiBond Solo Plus group for caries-affected and sound primary tooth dentin were 15.33 +/- 3.59 (MPa) and 11.96 +/- 2.30 (MPa) (P < 0.05), respectively. Micromorphological features between sound and caries-affected dentin were similar in both PQI and OptiBond Solo Plus groups. CONCLUSION: Both the adhesives showed significantly different bond strengths in caries-affected dentin but showed similar bond strengths in sound dentin.     

The bond of resin to different dentin surface characteristics

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.     

The effect on shear bond strength of rewetting dry dentin with two desensitizers

The difficulty related to achieving a balance between wet and dry dentin makes the dentin bonding technique extremely sensitive. This study evaluated the effect of rewetting dried dentin with two commercial desensitizing agents (Protect and HurriSeal) on the dentin shear bond strength of three total-etch dentin bonding agents (Syntac Single-Component, OptiBond Solo Plus and Prime & Bond NT) and compared both to applying these same bonding agents to moist dentin and dry dentin. Each bonding agent was paired with an appropriate resin composite from the same manufacturer (Table 1). Recently extracted, formalin-treated caries-free human molars were used. The occlusal surface of each tooth was ground to create a flat dentin surface. Then, each tooth was mounted in acrylic. Twelve groups (n = 15) were prepared: 1) Syntac Single-Component with Heliomolar resin composite (SSC/H) to moist dentin; 2) SSC/H to dry dentin; 3) SSC/H to dried dentin rewet with Protect; 4) SSC/H to dried dentin rewet with HurriSeal; 5) OptiBond Solo Plus with Point 4 resin composite (OBS+/P4) to moist dentin; 6) OBS+/P4 to dry dentin; 7) OBS+/P4 to dried dentin rewet with Protect; 8) OBS+/P4 to dried dentin rewet with HurriSeal; 9) Prime & Bond NT with TPH Spectrum resin composite (PBNT/TPH) to moist dentin; 10) PBNT/TPH to dry dentin; 11) PBNT/THP to dried dentin rewet with Protect and 12) PBNT/TPH to dried dentin rewet with HurriSeal. Groups 1, 5 and 9 were placed according to manufacturers' instructions (moist dentin) as control groups. All the other groups received a 15-second air blast after etching and prior to applying the one bottle adhesive or desensitizer and one bottle adhesive. Resin composite cylinders [4 mm in diameter and 2 mm in height] were then placed. The specimens were stored in distilled water at 37 degrees C for 24 hours prior to thermocycling 2,500 times (at 8 degrees C and 48 degrees C). Shear bond strengths (SBSs) were measured one week after fabrication by using a circular knife-edge and crosshead speeds of 0.5 mm/minute. Failure modes of debonded specimens were determined under a stereomicroscope (30x). Failed specimens with the low and high shear bond strengths in each group were evaluated under a low vacuum Scanning Electron Microscope (SEM-LV). One-way ANOVA and Tukey's tests were used to compare the different conditions for each bonding system. In the Syntac Single-Component bonding agent groups, there was no significant difference in shear bond strength between the control (15.73 MPa), dry (18.11 MPa) and HurriSeal (16.18 MPa) specimens. Protect specimens showed significantly lower shear bond strength (6.39 MPa). In the OptiBond Solo Plus bonding agent groups, there was no significant difference between the control (20.79 MPa) and the HurriSeal (21.29 MPa) groups, and both groups had significantly greater bonds than the dry (14.13MPa) and Protect (9.57 MPa) groups. In the Prime & Bond NT bonding agent groups, the shear bond strength of the HurriSeal group (20.73 MPa) was significantly higher than the other groups: control (8.05 MPa), dry (5.73 MPa) and Protect (5.45 MPa).     

Influence of surface wetness on bonding effectiveness of universal adhesives in etch‐and‐rinse mode

The purpose of this study was to evaluate whether surface wetness would influence the bonding effectiveness of universal adhesives in etch‐and‐rinse mode. All‐Bond Universal (AB), G‐Premio Bond (GP), Prime & Bond Active (PB), and Scotchbond Universal Adhesive (SU) were evaluated. Initial bond strengths and bond‐fatigue strengths of universal adhesives to both wet and dry enamel and dentin in etch‐and‐rinse mode were determined. Scanning electron microscopy observations of the adhesive interfaces were also conducted. The bond‐fatigue durability of universal adhesive to enamel in etch‐and‐rinse mode was influenced by the surface wetness, unlike that to dentin. The bond fatigue durability of AB and GP to dentin in etch‐and‐rinse mode was different depending on the surface wetness, unlike that of PB and SU. The thicknesses of the adhesive or hybrid layer of resin–dentin interfaces were not influenced by the surface wetness, but the length of resin tags in the wet group was longer than in the dry group. Some universal adhesives with the addition of specific components and optimization of water content can achieve stable bonds regardless of surface wetness, but the surface wetness of dentin is still a significant factor for universal adhesive bonding in etch‐and rinse mode, unlike that of enamel.     

Matrix metalloproteinase inhibitory properties of benzalkonium chloride stabilizes adhesive interfaces

This study evaluated the effects of different concentrations of benzalkonium chloride (BAC) on the preservation of adhesive interfaces created with two etch‐and‐rinse adhesives and its inhibitory properties on dentin matrix metalloproteinase (MMP) activity. The following groups were tested with the adhesive systems Optibond Solo Plus and All‐Bond 3: Group 1, adhesive without inhibitor (control); Group 2, topical 2.0% chlorhexidine (2.0% CHX); Group 3, phosphoric acid with 1.0%wt BAC (BAC‐PA); Group 4, 0.25% BAC‐adhesive (0.25% BAC); Group 5, 0.5% BAC‐adhesive (0.5% BAC); Group 6, 1.0% BAC‐adhesive (1.0% BAC); and Group 7, 2.0% BAC‐adhesive (2.0% BAC). Composite cylinders were fabricated, and shear bond strength (SBS) was evaluated after 24 h, 6 months, and 18 months of storage. Extracts from concentrated demineralized human dentin powder were subjected to SDS‐PAGE and incubated in the presence of 0.25, 0.5, 1.0, and 2.0% BAC. Overall, stable bonds were maintained for 18 months. Improved bond strengths were seen for 0.5% BAC and 1.0% BAC when bonding with Optibond Solo Plus, and for 0.25% BAC and 0.5% BAC when bonding with All‐Bond 3. Zymographic analysis revealed complete inhibition of gelatinolytic activity with BAC. Benzalkonium chloride, at all concentrations, inhibited dentin proteolytic activity, which seems to have contributed to the improved bond stability after 18 months for specific combinations of BAC concentration and adhesive.     

Microtensile bond strength of current dentin adhesives measured immediately and 24 hours after application

PURPOSE: To evaluate the immediate microtensile bond strengths achieved with representative adhesive systems from each of the four current bonding approaches. MATERIALS AND METHODS: Resin composite was bonded incrementally to flat, midcoronal dentin from 33 human molars, using the adhesives (Adper Scotchbond MP; Adper Scotchbond 1; Optibond Solo Plus; Clearfil SE Bond; AdheSE; Tyrian SPE + One Step Plus; Optibond Solo Plus self-etching; One-Up Bond F; iBond; Adper Prompt L-Pop; Xeno III) according to the respective manufacturer's instructions. The bonded specimens were immediately sectioned into sticks and underwent microtensile bond testing either immediately or after 24 h. Data were analyzed with two-way ANOVA and LSD tests. RESULTS: No significant differences were found between immediate and 24-h bond strengths (p > 0.05). However, significant differences were observed among adhesives (p = 0.001). The all-in-one adhesive iBond showed statistically lower values when compared to all the other adhesives. Adper Prompt L-Pop, Xeno III, Tyrian SPE + One Step Plus and One-Up Bond F, all self-etching adhesives, were significantly weaker than AdheSE, Optibond Solo Plus, Adper Scotchbond 1, Optibond Solo Plus self-etching, Clearfil SE Bond, and Adper Scotchbond MP, which did not differ statistically from each other. CONCLUSION: Microtensile bond strengths of representative adhesive systems from the four categories of bonding agents were not equivalent, with the lowest values recorded for the one-step self-etching adhesives. There were no differences in the bond strengths when measured immediately and after 24 h.     

One-day bonding effectiveness of new self-etch adhesives to bur-cut enamel and dentin

Self-etch adhesives try to solve difficulties commonly associated with the clinical application of etch-and-rinse adhesives. Their application procedure is considered less time-consuming and, more importantly, less technique-sensitive. The main objective of this study was to determine the bonding effectiveness to and the interaction with enamel/dentin of three contemporary one- and two-step self-etch adhesives by microtensile bond strength testing (microTBS), Fe-SEM and TEM when compared to a control two-step self-etch and a three-step etch-and-rinse adhesive. The one-step self-etch adhesive, Adper Prompt (3M ESPE), scored the lowest microTBS of all experimental and control adhesives tested. Conversely, the two-step self-etch adhesives Clearfil SE (Kuraray) and OptiBond Solo Plus Self-Etch (Kerr) approached the values obtained by the three-step etch-and-rinse control (OptiBond FL, Kerr) when bonded to enamel and dentin. Ultramorphological characterization showed that interfacial morphology and the pH of the self-etch primer/adhesive are strongly associated. The interaction with dentin varied from the formation of a submicron, hydroxyapatite-containing hybrid layer for the "mild" self-etch adhesive Clearfil SE to a 3-5 microm thick, hydroxyapatite-depleted hybrid layer for the "strong" self-etch adhesive Adper Prompt. The two-step self-etch adhesives AdheSE and OptiBond Solo Plus Self-Etch presented with a hybrid layer with a hydroxyapatite-depleted top part and a hydroxyapatite-containing base part and were therefore classified into a new group of self-etch adhesives, namely "intermediary strong" self-etch adhesives.     

Effect of MTAD on flexural strength and modulus of elasticity of dentin

The purpose of this study was to evaluate the effect of MTAD on the flexural strength and modulus of elasticity of dentin. Dentin bars were randomly assigned to eight groups treated with various concentrations of NaOCl (5.25%, 2.65%, 1.31%, 0.66%), 17% EDTA, MTAD, saline, or according to a clinical protocol with 1.3% NaOCl and then 5 min of MTAD. Specimens were subjected to flexural strength and modulus of elasticity tests. Two-sample t test (alpha = 0.05) showed no statistically significant differences between various groups except for a reduction in flexural strength for the 2-h MTAD group (p = 0.002) and the EDTA group (p = 0.002). A significant reduction of modulus of elasticity for the 2-h MTAD group (p < 0.001), EDTA group (p < 0.001), and 0.6% NaOCl (p < 0.002) also was noted. There was no significant difference in flexural strength and modulus of elasticity between the dentin bars exposed to saline or MTAD when applied according to the clinical protocol (p > 0.05). These results indicate that MTAD can be used as prescribed for clinical use without affecting the physical properties of the dentin.     

Increases in dentin-bond strength if doubling application time of an acetone-containing one-step adhesive

This study investigated the microtensile bond strength (microTBS) of a one-step self-etching adhesive to human dentin and bovine enamel following different bonding treatments. Occlusal portions of human molars and labial surfaces of bovine incisors were ground flat to provide uniform dentin and enamel surfaces, respectively. Futurabond was used following five different protocols: 1) according to the manufacturer's directions, 2) acid etched with 36% phosphoric acid (H3PO4) for 15 seconds, 3) 10% sodium hypochlorite (NaOCl) treated for two minutes after H3PO4-etching, 4) doubling the application time of the adhesive and 5) doubling the number of adhesive coats. Composite build-ups (6 mm in height) were constructed incrementally with Arabesk resin composite. The specimens were stored in 100% humidity for 24 hours at 37 degrees C and sectioned into beams of 1.0 mm2 cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/minute, and mean microTBS data (MPa) were analyzed by one-way ANOVA and post-hoc multiple comparisons tests (alpha = 0.05). Doubling the application time of Futurabond attained the highest microTBS to dentin; whereas, no differences among all bonding application parameters evaluated could be detected when the adhesive was applied to enamel.     

不同能量密度Nd:YAG激光照射对牙本质粘接强度的影响

目的:研究不同能量密度下Nd:YAG激光照射对牙本质粘接强度的影响。方法:36颗无龋第三磨牙去除冠方牙釉质,随机分为3组:对照组低能量密度激光照射组(1 W,85 J/cm²)和高能量密度激光照射组(4 W, 350 J/cm²)。每组牙再随机分为两个亚组,分别使用全酸蚀(Single Bond 2)或自酸蚀粘接剂(G-Bond)进行粘接以及树脂修复。进行微拉伸粘接强度测试,扫描电镜观察牙本质表面形貌及粘接界面纳米渗漏情况。激光扫描共聚焦荧光显微镜下观察粘接界面树脂突形态及数量。结果:全酸蚀粘接中,低密度激光照射对粘接强度无影响,高密度激光照射后粘接强度相比对照组降低(P<0.05);自酸蚀粘接中,低密度激光照射后粘接强度比对照组显著下降(P<0.05),高密度激光照射对粘接强度无影响。低密度激光照射不增加粘接界面纳米渗漏,高密度激光照射后样本纳米渗漏相比对照组均显著增加(P<0.05)。结论:低能量密度的激光照射后使用全酸蚀粘接系统粘接效果较好;高能量密度的激光照射后使用自酸蚀粘接系统效果较好。     

The use of flowable composites as filled adhesives.

OBJECTIVE: The effect of filled adhesives on bonding resin composites to dentin has not been fully understood. Due to their filler content, filled adhesives may act as stress breakers. The aim of this in vitro study was to evaluate the use of flowable composites of different viscosities on bonding to enamel and dentin without the use of an intermediate bonding resin. MATERIALS AND METHODS: Enamel and dentin bond strengths of OptiBond FL, Syntac Classic, and EBS Multi combined either with their proprietary bonding agent or a flowable resin composite (Ultraseal XT Plus or Revolution) were measured. The tests were carried out with a microtensile device at a crosshead speed of 1mm/min after 24h of storage at 37 degrees C in water. Mean bond strengths were analyzed using the Wilcoxon test and multiple comparisons according to the Mann-Whitney U-test. The micro-morphology of corresponding resin-dentin interfaces of the same teeth were analyzed using SEM and TEM. RESULTS: The control groups with adhesive systems used as per manufacturers' protocol showed bond strengths of 38.9-41.1 MPa to enamel and 28.8-33.4 MPa to dentin. With respect to bond strength to etched enamel, only Ultraseal XT Plus as bonding resin reached the level of the control groups. When used as bonding agents on dentin, both flowable composites produced lower microtensile bond strengths to etched and primed dentin than did the control groups. Micro-morphological analysis using SEM and TEM resulted in hybrid layer formation for both control and experimental groups. However, many areas of the resin-dentin interface showed insufficient penetration of the flowable composites at the top of the hybrid layer as well as numerous tubules obstructed by filler particles. CONCLUSIONS: The flowable composites tested in this study should not be used to replace bonding agents. Flowable composites of thinner viscosity, such as Ultraseal XT Plus, may bond to enamel adequately without the requirement of an intermediate bonding resin.     

Dentin and enamel bond strengths of dual-cure composite luting agents used with dual-cure dental adhesives

OBJECTIVE: The purpose of this in vitro study was to evaluate and compare dentin and enamel bond strengths obtained with dual-cure composite luting agents when used with dual-cure dental adhesives. METHODS: Human molars were ground flat to expose enamel (n=80) or dentin (n=80). Specimens in each substrate group were randomly assigned to eight treatment sub-groups, according to four adhesive-luting agent combinations and two test conditions (with or without thermocycling). Pre-polymerized composite resin posts (TPH Spectrum) were luted to either the enamel or dentin surfaces with one of the following adhesive-luting agent combinations: (1) Xeno IV Dual Cure (dual-cure self-etch adhesive) and Calibra (dual-cure luting agent); (2) Prime & Bond NT Dual Cure (dual-cure total-etch adhesive) and Calibra; (3) OptiBond All-in-One Dual Cure (dual-cure self-etch adhesive) and Nexus 2 Dual Syringe (dual-cure luting agent); (4) OptiBond Solo Plus Dual Cure (dual-cure total-etch adhesive) and Nexus 2 Dual Syringe. For each treatment sub-group, half the specimens (n=10) were tested after 24h storage in water at 37 degrees C, and the other half (n=10) were tested after thermocycling for 1800 cycles between water baths held at 5 and 55 degrees C, with a dwell time in each bath of 30s, and a transfer time of 10s. Bond strengths were measured in shear mode, and expressed in MPa. The fracture mode (adhesive, cohesive, mixed) was examined. Data were analyzed for statistical significance with a factorial ANOVA and post hoc tests. RESULTS: Mean enamel bond strengths ranged from 8.4MPa for non-thermocycled OptiBond All-in-One|Nexus 2 to 35.5MPa for non-thermocycled Prime & Bond NT|Calibra. Mean dentin bond strengths ranged from 14.5MPa for non-thermocycled OptiBond Solo Plus|Nexus 2 to 30.9MPa for thermocycled Xeno IV|Calibra. The fracture mode was predominantly adhesive for all groups. CONCLUSIONS: On enamel, the total-etch adhesives performed better than their self-etch counterparts, while in dentin, the opposite was found, i.e., the self-etch adhesives performed better than their total-etch counterparts. Thermocycling for 1800 cycles did not affect the SBS of the materials tested to dentin and enamel.     

Hardness and microshear bond strength to enamel and dentin of permanent teeth with hypocalcified amelogenesis imperfecta

International Journal of Paediatric Dentistry 2011; 21: 314–320 Background. Adhesive procedures are often required to restore teeth affected by hypocalcified amelogenesis imperfecta (HAI). Aim. To evaluate the hardness of enamel/dentin of teeth affected by HAI and the bond strength to these substrates, as well the influence of 5% NaOCl on bond strength. Design. Permanent molars presenting HAI and sound third molars were used. Enamel surfaces were wet‐flattened and Knoop hardness was assessed. The two‐step, etch‐and‐rinse adhesive Single Bond 2 (3M ESPE) was applied and resin cylinders bonded to the surfaces and submitted to microshear testing. The subjacent medium dentin was then exposed by wet‐grinding. Hardness readings and microshear testing were carried out again. The relationship between hardness and bond strength was assessed by nonlinear regression analysis. Results. Hardness of normal enamel was higher than hardness of enamel affected by HAI, whereas dentin hardness did not differ from normal to HAI‐affected teeth. Enamel and dentin hardness were similar for teeth affected by HAI. Higher bond strengths were obtained to the normal tooth tissues. Dentin bond strength was higher than enamel bond strength. NaOCl exposure did not influence bond strengths. A positive linear relationship between enamel hardness and bond strength was observed. Conclusion. HAI imposes challenges to bonding to enamel and dentin.     

Shear bond strength and SEM evaluation of composite bonded to Er:YAG laser-prepared dentin and enamel.

OBJECTIVES: The purpose of this study was to evaluate dentin and enamel bond strength to resin composite following high-speed rotary or Er:YAG laser preparation using a total etch adhesive system. The microstructure of resin-tooth interfaces was also investigated. METHODS: Human dentin and enamel specimens were prepared with a high-speed handpiece (KaVo) or Er:YAG laser (DELight) at manufacturer's recommended settings and etched with either 37% H(3)PO(4), laser etched, or not etched. Composite rods (Z-250, 3M/ESPE) were bonded to specimens with an adhesive (Adper Scotchbond Multi-Purpose, 3M/ESPE). After thermocycling, specimens were tested in shear to failure. RESULTS: Two-factor ANOVA detected significant differences in the main effects of preparation and etch type, and interaction (p<0.001). Post hoc analyses showed that in both dentin and enamel, only the acid-etched specimens had significantly higher mean bond strengths, with rotary-prepared specimens having significantly higher mean bond strengths versus laser prepared specimens. Within each preparation type, in both dentin and enamel, acid etch was better than laser etch, and laser etch was better than no etch. Scanning electron microscopy of laser-ablated specimens demonstrated significant surface scaling and subsurface fissuring beyond normal resin penetration depth. SIGNIFICANCE: Adhesion to laser-ablated or laser-etched dentin and enamel was inferior to that of conventional rotary preparation and acid etching.     

Bond strengths of nonrinsing adhesives.

OBJECTIVE: The purpose of this study was to determine enamel and dentin bond strengths of a nonrinsing "all-in-one" adhesive and of a nonrinsing conditioner combined with a 1-bottle adhesive. METHOD AND MATERIALS: Specimens were obtained from 240 bovine teeth ground to expose enamel or dentin surfaces. Ten enamel and 10 dentin specimens were randomly assigned to each of 12 different combinations of adhesive system (Prompt L-Pop; no etch + Prime & Bond NT; NRC + Prime & Bond NT; 36% phosphoric acid + Prime & Bond NT; no etch + Prime & Bond 2.1; 36% phosphoric acid + Prime & Bond 2.1) and restorative material (resin composite; polyacid-modified resin composite ["compomer"]). After the application of the adhesive system, a No. 5 gelatin capsule filled with the restorative material was seated against the enamel or dentin surface. After 24 hours in distilled water at 37 degrees C, the specimens were thermocycled and the shear bond strengths were measured. RESULTS: For resin composite, etching with phosphoric acid resulted in the highest bond strengths to enamel. For compomer, the highest enamel bond strengths were achieved with both phosphoric acid and Prompt L-Pop. Treating dentin with Prime & Bond NT without etching provided the highest mean bond strength for composite. For compomer, treating dentin with Prime & Bond NT resulted in the highest mean bond strengths, regardless of the conditioner. CONCLUSION: Compomer and resin composite exhibited statistically similar bond strengths. Bond strengths to dentin were significantly lower than those to enamel.     

Effect of sodium ascorbate on bond strength of different adhesive systems to NaOCl-treated dentin

The aim of this study was to evaluate the effects of sodium ascorbate on bond strength of different adhesive systems to NaOCl-treated dentin. Eighty extracted molar teeth were used in the study. The buccal enamel surfaces were removed to obtain a flat dentin surface. The teeth were mounted in self-curing resin and dentin surfaces were irrigated with NaOCl for 10 min. Half of the specimens were treated with sodium ascorbate for 10 min. The teeth were randomly assigned to four subgroups according to the adhesive systems used (Clearfil SE Bond, Clearfil Tri-S Bond, Adper Prompt-L-Pop, Adper Single Bond 2). Bond strengths were determined with a Universal Testing Machine, at a crosshead speed of 0.5 mm/min. Data were statistically analysed using anova at a significance level of 0.05. Two-way anova revealed that the effect of sodium ascorbate application on bond strength of adhesive systems to NaOCl-treated dentin was statistically significant (P < 0.05). The bond strength results were significantly influenced by the application of sodium ascorbate (P < 0.05) and there was a significant difference between the adhesive systems (P < 0.05). Although statistically significant differences were not demonstrated in all adhesive resin groups, sodium ascorbate application after NaOCl treatment improved the bond strength values.     

Bonding of resin to artificially carious dentin

PURPOSE: To evaluate the bond strength of adhesive resins to artificially carious dentin specimens which were previously exposed to an acid buffer solution for various periods. MATERIALS AND METHODS: Flat dentin disks were obtained from superficial occlusal dentin of extracted human third molars and polished with wet silicon carbide paper. Dentin disks were immersed in acid buffer solution for different periods to create the demineralized dentin layer. The first group of demineralized specimens was used for the evaluation of demineralization depth under SEM and the second group was used for the bond strength measurement. Shear bond strengths mediated by three dentin adhesives (Clearfil SE Bond, OptiBond Solo Plus Total-Etch, and OptiBond Solo Plus Self-Etch) were examined. A 0.75-mm-diameter area of dentin was bonded according to the manufacturers' instructions before placing a 0.5-mm-high resin composite cylinder. The bonds were stressed in shear at a crosshead speed of 1 mm/min. All data were analyzed using ANOVA and LSD multiple comparison test. RESULTS: Depth of demineralization increased with the prolongation of demineralizing time. After dentin specimens were demineralized for up to 24 h, bond strengths of the self-etching adhesives were significantly higher than those of the total-etch adhesive. However, for longer demineralization periods, no statistical differences in bond strengths were observed. SEM photographs showed that resins cannot thoroughly infiltrate through the whole depth of the demineralized dentin layer. CONCLUSION: Bond strengths to demineralized, artificially carious dentin were affected by the depth of demineralization and adhesive resins used.