Adper Easy Bond Research Articles

Effect of Hydro- abrasion versus Conventional Cavity Preparation on the Clinical Performance of Composite Resin Restoration

Aim: To evaluate the effect of hydro abrasion versus the conventional drill method of cavity preparation on the clinical performance of composite restoration over one year follow up period. Materials and methods: Twenty patients with occlusal carious lesions were selected and examined with DIAGNO cam and ICDAS visual criteria to select teeth having ICDAS Code 3 or 4. Forty lesions were randomly divided into two groups (n=20) according to the method of caries removal. Cavities were prepared by the conventional drill method in group I and by hydro-abrasion in group II. Cavities of both groups were restored by self-etch adhesive (Adper Easy Bond) and nano- filled composite (Filtek Z350XT). All restorations were evaluated after 24 hours, after 9 and 12 months according to (USPHS) criteria for retention, marginal adaptation, postoperative sensitivity, marginal discoloration, and secondary caries. Results: Mild, moderate - severe and very severe pain was recorded in group I While in group II, only mild pain was recorded in (40%) of cases. The st. analysis of the collected data related to the tested USPHS criteria revealed 100% Alpha scoring regarding retention, marginal adaptation and secondary caries in both groups throughout the study period. The gap width measured under SEM was found increased sig. by time in both groups. Marginal discoloration was observed in the two groups after nine and 12 months. Post-operative hypersensitivity was found only in group I in 100% of cases at the base line and was disappeared during the next follow up period.

Evaluating The Effect of pH of Dentin Bonding Agents on Dentin in Relation to the Push-Out Bond Strength of Composites in Class I Cavities in-vitro

INTRODUCTION: Today, the popularity of amalgam as restorative material has decreased due to poor esthetic characteristics and mercury contamination with composite resin materials becoming a choice among the both dentists and patients. AIM: The objective of this in-vitro study was to evaluate the effect of pH of dentin bonding agents (Adper Easy Bond and Xeno V) on dentin in relation to push out bond strength of composite restored with Filtek bulk fill posterior restorative composites.MATERIALS AND METHOD: Sixty caries free human molars with no cracks or previous restorations were used for investigation. Standard box-type Class-I Cavities of 3.5 mm x 3.5 mm and depth of 4 mm were prepared on the occlusal surface of the molars. Teeth were randomly divided into 2 groups namely Group A, Group B of 30 teeth each, according to the dentin adhesives applied i.e Adper Easy bond and Xeno V. Two bonding agents with different pH were selected for the study. One was Adper Easy Bond with Ultra mild pH of 2.7. Other was Xeno V Self etch with strong pH of <1.3. Push-out test was performed by placing specimens within a centralizing ring to ensure a centered application of the load, resting on another ring, with a central hole slightly larger than the restoration diameter. The test was performed with a universal Testing Machine to express bond strength in mega pascals (MPa), load value in Newton (N). After testing the push-out bond strength, the samples were analyzed under a stereomicroscope.RESULTS: Adper Easy bond with an ultra mild pH 2.7 is better as compared to Xeno V Self etch with strong pH of <1.3.The most common mode of failure observed with Adper was mixed fracture and cohesive dentin fracture, while in Xeno V, adhesive failure between resin and dentin and cohesive resin fracture was observed. The mean maximum force was significantly more among Adper compared to Xeno V.CONCLUSION: Comparison of dentin bonding agents in this in vitro study revealed that the push out bond strength of Adper Easy performed better than Xeno V.

Activation of matrix-bound endogenous proteases by self-etch adhesives.

The study evaluated changes in total enzymatic activity and degradation of demineralized dentin following the application of universal or self-etch adhesives. The universal adhesives -Scotchbond Universal (SU) and All-Bond Universal (ABU) and self-etch adhesives -Adper Easy Bond (EB) and G-aenial Bond (GB) were used for 2 min pretreatment of the dentin beams. Phosphoric acid (PA) treatment as well as no treatment served as controls. Total enzymatic activity was analyzed before and after treatment, collagen degradation was assessed using mass loss, C-terminal telopeptide (CTX) and C-terminal-telopeptide of type I collagen (ICTP) release (24 h, 3-day, 3-week). Over three weeks of incubation, ICTP release of ABU treated beams was significantly higher than other groups (p<0.05), except for SU treated beams (p>0.05) and CTX release of GB treated beams was the highest among the groups with statistically significant difference (p<0.05). The results confirm that the universal adhesives tested have also potential to increase the enzymatic activity in dentin.

Knoop Hardness of Self-Etch Adhesives Applied on Superficial and Deep Dentin.

Statement of the Problem: Low pH of self-etch adhesives might cause suboptimal polymerization.Purpose: This study aimed to evaluate the effect of dentin depth (deep and superficial) on polymerization efficacy of two self-etch adhesives, with different pH by means of Knoop hardness test.Materials and Method: In this in vitro study, sixty sound molars were used to prepare 30 superficial dentin and 30 deep dentin specimens. Dentin specimens of each depth were randomly distributed into two equal subgroups (N=15) and bonded by either Adper Prompt L-Pop (strong self-etch adhesive) or Adper Easy Bond (mild self-etch adhesive). Knoop hardness test was employed to evaluate degree of cross-linking of the adhesives. Data were analyzed with SPSS 16, using two-way ANOVA to compare mean hardness values of the study groups (p< 0.05).Results: There was no interaction effect between dentin depth and the type of adhesive (p= 0.36). Regardless of dentin depth, hardness of Adper Easy Bond was significantly higher than that of Adper Prompt L-pop (p< 0.001). Moreover, both the adhesives showed higher hardness when bonded to superficial dentin compared to deep dentin (p< 0.001).Conclusion: Degree of cross-linking of the self-etch adhesive with mild acidity was more than that of the strong self-etch adhesive after light-curing. Surface hardness of both adhesives was higher on superficial dentin compared to deep dentin.

Effect of Simulated Pulpal Pressure on Knoop Hardness of Two Self-etch Adhesives with Different Aggressiveness

Simulated pulpal pressure (PP) has been shown to affect the bond strength and nanoleakage of different adhesives at dentin interfaces but the effect of simulated PP on polymerization of adhesives has not been studied yet. Furthermore, it has been proposed that strong and mild self-etch adhesives have different polymerization behaviors. This study aimed to evaluate the effect of simulated PP on polymerization of two self-etch adhesives, Adper Prompt L-Pop (APLP) and Adper Easy Bond (AEB), by means of the Knoop hardness test. Sixty caries-free human molars were used to prepare deep dentin specimens with a mean remaining dentin thickness of 0.9 mm. The specimens were bonded in the absence or presence of PP. The specimens were assigned to four equal groups (n = 15) as follows: AEB/-PP, APLP/-PP, AEB/+PP, and APLP/+PP. Bonding procedures were completed; then the specimens' hardness was measured with the Knoop test. Data were analyzed with two-way ANOVA and the t test. In the absence of PP, the hardness of AEB was significantly higher than that of APLP (p < 0.001). In contrast, when PP was simulated, the hardness of APLP was higher than that of AEB (p = 0.002). The hardness of AEB was not influenced by the presence of PP (p = 0.153). Simulation of PP resulted in a significant improvement in the hardness of APLP (p < 0.001). The polymerization degree of strong self-etch adhesive was lower compared to mild self-etch adhesive. In the presence of hydrostatic PP, the polymerization degree of strong self-etch adhesive was higher than mild self-etch adhesive. Dentin moisture caused by positive PP might improve polymerization of strong self-etch adhesives.

Bonding Performance of Simplified Dental Adhesives with Three Application Protocols: An 18-month In Vitro Study.

To evaluate the influence of application protocol on the shear bond strength (SBS) and nanoleakage of simplified adhesives over 18 months. 810 dentin slices were obtained from 405 caries-free human molars. They were randomly assigned to 54 experimental groups resulting from the combination of "adhesive" (Adper Scotchbond 1XT [S1XT], Solobond M [SM], Scotchbond Universal Adhesive in etch-and-rinse mode [SUER] and self-etch mode [SUSE], Adper Easy Bond [EB], Clearfil S3 Bond Plus [CS3]), "application protocol" (manufacturer's instructions [MI], two extra layers of adhesive [EL], hydrophobic resin layer [HL]), and "aging time" (24 h [24H], 6 months [6M], and 18 months [18M] in water). SBS tests were carried out using a Watanabe device followed by failure mode analysis. For the nanoleakage study, specimens from 54 additional molars were prepared as previously described, immersed in ammoniacal silver nitrate, and evaluated with SEM. SBS data were analyzed with ANOVA followed by Tukey's post-hoc tests; failure mode data were analyzed using chi-squared tests (α = 0.05). Nanoleakage data were analyzed with the Kruskal-Wallis test followed by LSD tests (α = 0.05). After 18M, S1XT and SUSE achieved the highest mean SBS (p < 0.05). Regarding the application protocols, EL and HL provided higher mean SBS than those obtained with MI (p < 0.05). HL resulted in the highest mean SBS and the lowest mean nanoleakage after 18M. Simplified adhesives may need an extra hydrophobic resin layer to achieve a stable and durable adhesive interface. The self-etch approach should be recommended for the universal adhesive.

Does lining class-II cavities with flowable composite improve the interfacial adaptation?

The objective of this study was to assess in-vitro interfacial cavity adaptation of different adhesive/composites systems in class-II restoration using SS-OCT and to confirm the findings with a confocal laser scanning microscope (CLSM). Standardized rectangular-shaped class-II cavities were prepared on 24 extracted human molar teeth, bonded with adhesive and lined with flowable composite. Cavities were further restored by bulk filling using packable composite. Specimens were divided into four groups (n = 7) according to restorative materials used; PrimeFil with Estelite Posterior composites (PF; Tokuyama Dental), Clearfil Tri-S Bond Plus with Majesty LV flowable and Majesty Posterior composites (TS; Kuraray Noritake Dental), Adper Easy bond with Filtek Z350 XT flowable and Filtek Z350 XT packable composites (AE; 3 M ESPE) or Palfique Bond adhesive with Estelite Flow Quick flowable and Estelite Posterior composites (BF; Tokuyama Dental). To evaluate the cavity adaptation of these restorative materials, tomographic images of pulpal (P) and gingival (G) walls were obtained by SS-OCT with a central wavelength of 1330 nm, followed by cross-sectioning and CLSM observation to confirm OCT findings. The results showed a significant increase in the backscattered reflection was attributed to the interfacial gaps. AE groups demonstrated the highest interfacial adaptation percentage (p < 0.05), while TS and PF groups showed no significant difference (p > 0.05). BF group presented the least adaptation percentage, and the gaps were frequently observed at the adhesive/composite interface. In addition to the sensitivity of the SS-OCT to the interfacial gaps, the success of flowable lining relies on the interactions between the adhesive/tooth and adhesive/composite substrates.

Comparative evaluation of post operative sensitivity in etch and rinse and self etch adhesives: A longitudinal study

Introduction: It is presumed that self- etch adhesives are prevent post operative sensitivity in posterior restorations. In this study author tested a hypothesis: a self etch adhesives would results in postoperative sensitivity than etch and rinse. Methods patients were recruited on the basis of class I and class II restorations in molars and premolars. The author placed 60 restorations with self etch adhesive [Adper Easy Bond, 3M ESPE, Germany] and 72 restorations with Tetric N-Bond [Ivoclar-Vivadent, India], which uses 34% phosphoric acid to etch enamel and dentine simultaneously. Cavity preparations were of established design for composite restoration, with no beveling on occlusal surface with supported enamel margins. Restoration done with corresponding composite materials under rubber dam isolations. The restored teeth were evaluated preoperatively and a 15 days, 2 months and 6 months postoperatively for sensitivity to cold [ice], air and masticatory forces. Results analysis of variance reveled no statically significant difference in postoperative sensitivity between the self etch and etch and rinse at any recall time. Conclusion of study was that the self adhesive did not differ from the etch and rinse in terms of sensitivity. Keywords: Self etch adhesive, Total etch, Sensitivity, Beveling.

Effect of Methods of Biosilicate Microparticle Application on Dentin Adhesion.

Restorative procedures associated with bioglasses have shown to be a strategy to satisfy the contemporary concept of minimally invasive dentistry. Thus, the aim of this study was to evaluate bond strength to dentin treated by two different methods of biosilicate microparticle application. Dentin surfaces from 30 sound human molars were exposed and randomly assigned into three groups (n = 10) according to the surface treatment: (1) blasting with biosilicate microparticles (distance = 1 cm/pressure = 5 bar/time = 1 min); (2) 10% biosilicate microparticles paste; and (3) control (no treatment). After, dentin surfaces were restored with self-etch adhesive (Adper Easy Bond) and nanofilled composite (Filtek Z350). Specimens were sectioned perpendicularly to the adhesive interface to obtain sticks (cross-section area = 1 mm2), which were submitted to microtensile test (0.5 mm/min; 50 kgf). Data were analyzed by ANOVA and Tukey’s test (α = 5%). Dentin/adhesive interfaces were morphologically analyzed by scanning electron microscopy (SEM). Data analysis showed that biosilicate-treated groups reached similar results (p > 0.05) and both of them demonstrated higher values (p < 0.05) than control group. SEM micrographs revealed hybridization with clear resin tags and no separation between resin-dentin adhesive interfaces. Within the limitations of this study, surface treatment with biosilicate positively influenced the adhesion to dentin and does not alter the morphology of the adhesive interface.

Effects of boundary condition on shrinkage vectors of a flowable composite in experimental cavity models made of dental substrates.

Bond strength to enamel and dentin depends on the bonding approach or condition. This study investigated the effects of the boundary conditions, in terms of the bonding substrate and the bonding condition, on the shrinkage vectors of a flowable composite. An experimental cylindrical cavity (diameter = 6mm, depth = 3mm) consisting of the enamel floor and the surrounding dentin cavity walls was prepared for the "enamel-floor" group. Cylindrical cavities of the same dimensions were prepared with access from the occlusal enamel into dentin and served as controls. Each cavity model group was divided and bonded with two bonding conditions (n = 9): a self-etch (Adper Easy Bond, 3M ESPE) and a total-etch approach (OptiBond FL, Kerr). The composite (Tetric EvoFlow, Ivoclar Vivadent) was mixed with glass beads, applied to the cavity, scanned twice by micro-CT (uncured and cured states). The scans were evaluated by rigid registration, sphere segmentation, and registration for computing shrinkage vectors. The free surface of all restorations moved downward. The shrinkage vectors in the experimental cavity model pointed downward towards the enamel cavity floor, and the net axial movement was downward. In the control group, shrinkage vectors additionally moved upward, away from the cavity floor. The effect of the bonding substrate and the bonding condition was investigated for the shrinkage vectors and the axial movement (univariate ANOVA). The bonding substrate, enamel, influenced the shrinkage vectors' direction, while the bonding condition caused only variations in the magnitude. Bonding to enamel influences shrinkage vectors' direction, while the bonding condition plays only a minor role. Graphical abstract ᅟ.

Clinical Follow-up of a Fissure Sealant Placed Using Different Adhesive Protocols: A 24-month Split-mouth Study

The purpose of this study was to evaluate the retention rates of a fissure sealant placed using different adhesive protocols over 24 months. Twenty-four subjects with no restorations or caries received fissure sealants (Clinpro Sealant, 3M ESPE) placed using different adhesive protocols. A total of 292 sealants were placed as follows by two previously calibrated dentists using a table of random numbers (n=73): group I, acid-etch/without adhesive; group II, with a self-etch adhesive (Adper Easy Bond, 3M ESPE); group III, with an etch-and-rinse adhesive (Adper Single Bond 2, 3M ESPE); group IV, with acid + self-etch adhesive (Adper Easy Bond). Two other calibrated examiners independently evaluated the sealants at baseline and at six-, 12-, 18-, and 24-month recalls. Each sealant was evaluated in terms of caries formation being present or absent and retention using the following criteria: 1 = total retention, 2 = partial loss, and 3 = total loss. Pearson's χ2 test was used to evaluate differences in retention rates among the sealants for each evaluation period. At the end of 24 months, total retention rates were 57.5%, 27.4%, 84.9%, and 76.7% in the acid-etch, self-etch adhesive, etch-and-rinse adhesive, and acid + self-etch adhesive groups, respectively. Although there were no statistically significant differences between the retention rates among the adhesive protocols at 6 months ( p=0.684), significant differences were observed at the 12-, 18-, and 24-month evaluations. At 24 months, the lowest retention rates were observed in the self-etch group ( p<0.05). No caries development was observed in any of the groups. The retention rate of sealants placed using self-etch adhesive was poor compared with the other groups.

Evaluation of bioflavonoids on the immediate and delayed microtensile bond strength of self-etch and total-etch adhesive systems to sound dentin.

This study aims to evaluate the effect of two bioflavonoids (epigallocatechin-3-gallate [EGCG] and catechin) and a protein inhibitor (chlorhexidine [CHX]) on the immediate and delayed microtensile bond strength of self-etch and total-etch adhesive systems to sound dentin. The occlusal surfaces of 96 mandibular human third molar teeth specimens were ground after removal of the excess tissues, to expose the middle dentin. The dentin specimens were randomly allocated into four groups, each consisting of 24 teeth (n = 24) according to the application of the enzyme inhibitor. The adhesive system used in this study was Adper easy bond, a self-etch adhesive system, and Adper Single Bond 2, a total-etch adhesive system. Microtensile bond strength testing was conducted using thermocycler 2000, Heto-Holten A/S. All the three enzyme inhibitors increase the bond strength values of the resin-dentin interphase when used during dentin bonding. The EGCG enzyme inhibitor has shown the highest immediate bond strength to dentin when used with both the adhesive systems.

Effects of occlusal cavity configuration on 3D shrinkage vectors in a flowable composite.

The objective of this study was to investigate the effects of cavity configuration on the shrinkage vectors of a flowable resin-based composite (RBC) placed in occlusal cavities. Twenty-seven human molars were divided into three groups (n = 9) according to cavity configuration: "adhesive," "diverging," and "cylindrical." The "adhesive" cavity represented beveled enamel margins and occlusally converging walls, the "diverging" cavity had occlusally diverging walls, and the "cylindrical" cavity had parallel walls (diameter = 6mm); all cavities were 3mm deep. Each prepared cavity was treated with a self-etch adhesive (Adper Easy Bond, 3M ESPE) and filled with a flowable RBC (Tetric EvoFlow, Ivoclar Vivadent) to which had been added 2wt% traceable glass beads. Two micro-CT scans were performed on each sample (uncured and cured). The scans were then subjected to medical image registration for shrinkage vector calculation. Shrinkage vectors were evaluated three-dimensionally (3D) and in the axial direction. The "adhesive" group had the greatest mean 3D shrinkage vector lengths and upward movement (31.1 ± 10.9μm; - 13.7 ± 12.1μm), followed by the "diverging" (27.4 ± 12.1μm; - 5.7 ± 17.2μm) and "cylindrical" groups (23.3 ± 11.1μm; - 3.7 ± 13.6μm); all groups differed significantly (p < 0.001 for each comparison, one-way ANOVA, Tamhane's T2). The values and direction of the shrinkage vectors as well as interfacial debonding varied according to the cavity configuration. Cavity configuration in terms of wall orientation and beveling of enamel margin influences the shrinkage pattern of composites.

Effect of a one-step self-etch adhesive on endogenous dentin matrix metalloproteinases.

Degradation of the hybrid layer created in dentin by dentin adhesives is caused by enzyme activities present within the dentin matrix that destroy unprotected collagen fibrils. The aim of the present study was to evaluate the effect of a one-step self-etch adhesive system on dentinal matrix metalloproteinases 2 and 4 (MMP-2 and MMP-9, respectively) using in situ zymography and an enzymatic activity assay. The null hypothesis tested was that there are no differences in the activities of dentinal MMPs before and after treatment with a one-step adhesive system. The MMP-2 and MMP-9 activities in dentin treated with the one-step adhesive, Adper Easy Bond, were quantified using an enzymatic activity assay system. The MMP activities within the hybrid layer created by the one-step adhesive tested were also evaluated using in situ zymography. The enzymatic assay revealed an increase in MMP-2 and MMP-9 activities after treatment with adhesive. In situ zymography indicated that gelatinolytic activity is present within the hybrid layer created with the one-step self-etch adhesive. The host-derived gelatinases were localized within the hybrid layer and remained active after the bonding procedure. It is concluded that the one-step self-etch adhesive investigated activates endogenous MMP-2 and MMP-9 with the dentin matrix, which may cause collagen degradation over time.

Degree of Conversion and Oxygen-Inhibited Layer Effect of Three Dental Adhesives.

This study investigated the effect of the oxygen-inhibited layer on the degree of conversion (DC) of three dental adhesives, comparing two different protocols. Quartz–tungsten–halogen (QTH) light curing and light-emitting diode (LED) were used to cure three adhesives: OptiBond All in One (OAIO), Adper Easy Bond (AEB) and ExciteF (EXF). The DC was calculated utilizing Fourier Transform infrared spectroscopy (FTIR) (n = 12). The two protocols used were as follows: (i) prevent the oxygen-inhibited layer using a Mylar plastic strip pushed onto each bonding adhesive; and (ii) polymerize samples without a plastic strip. The data was analyzed statistically by a three-way ANOVA, and Tukey Test (a = 0.05). The presence of an oxygen-inhibited layer reduced the DC of the adhesives by 64% for EXF, 46% for AEB and 32% for OAIO. This study suggests that there are differences among the oxygen-inhibited layers present for the adhesives tested.

Dentin-composite bond strength measurement using the Brazilian disk test

ObjectivesThis study presents a variant of the Brazilian disk test (BDT) for assessing the bond strength between composite resins and dentin. MethodsDentin-composite disks (ϕ 5mm×2mm) were prepared using either Z100 or Z250 (3M ESPE) in combination with one of three adhesives, Adper Easy Bond (EB), Adper Scotchbond Multi-Purpose (MP) and Adper Single Bond (SB), and tested under diametral compression. Acoustic emission (AE) and digital image correlation (DIC) were used to monitor debonding of the composite from the dentin ring. A finite element (FE) model was created to calculate the bond strengths using the failure loads. Fracture modes were examined by scanning electron microscopy (SEM). ResultsMost specimens fractured along the dentin-resin composite interface. DIC and AE confirmed interfacial debonding immediately before fracture of the dentin ring. Results showed that the mean bond strength with EB (14.9±1.9MPa) was significantly higher than with MP (13.2±2.4MPa) or SB (12.9±3.0MPa) (p<0.05); no significant difference was found between MP and SB (p>0.05). Z100 (14.5±2.3MPa) showed higher bond strength than Z250 (12.7±2.5MPa) (p<0.05). Majority of specimens (91.3%) showed an adhesive failure mode. EB failed mostly at the dentin-adhesive interface, whereas MP at the composite-adhesive interface; specimens with SB failed at the composite-adhesive interface and cohesively in the adhesive. ConclusionsThe BDT variant showed to be a suitable alternative for measuring the bond strength between dentin and composite, with zero premature failure, reduced variability in the measurements, and consistent failure at the dentin-composite interface. Clinical significanceThe new test could help to predict the clinical performance of adhesive systems more effectively and consistently by reducing the coefficient of variation in the measured bond strength.

Degree of Conversion of Self-etch Adhesives: In Situ Micro-Raman Analysis.

Degree of conversion (DC) affects the physicochemical properties of dental adhesives. The aim of this study was to measure the DC within the hybrid layer of four one-step self-etch adhesives using Raman microspectroscopy. The hypothesis tested was that there was no difference among the tested adhesives. The selected one-step self-etch adhesives (Clearfil S3 Bond Plus, I-BOND, G-BOND, and Adper Easy Bond) were applied on human dentin disks and polymerized in accordance with the manufacturers' instructions. Specimens were transversally cut to expose the bonded interfaces to the micro-Raman beam, and Raman spectra were collected along the dentin/adhesive interface. Measurements were performed at 1-μm intervals. The relative intensities of bands associated with the C=C bond (at 1640 cm-1) and an internal stable peak (1610 cm-1) were determined to calculate the degree of conversion within the hybrid layer. Data were statistically analyzed with Kolmogorov-Smirnov and Bartlett tests and Kruskal-Wallis and Mann-Whitney U-tests. The DC ranked as follows: G-BOND (93%±6%) ≥ Adper Easy Bond (92%±6%) ≥ I-BOND (89%±7%) > Clearfil S3 Bond Plus (80%±14%) (p<0.05). Based on the results of this study, all of the tested self-etch adhesives showed a clinically acceptable DC that was material dependent.

Relationship between thin-film bond strength as measured by a scratch test, and indentation hardness for bonding agents

ObjectivesTo evaluate thin-film bond strength between a bonding agent and human dentin, using a scratch test, and the characteristics and accuracy of measurement. MethodsOne-step bonding agents (BeautiBond; Bond Force; Adper Easy Bond; Clearfil tri-S Bond) and two-step bonding agents (Cleafil SE Bond; FL-Bond II) were investigated in this study. Flat dentin surfaces were prepared for extracted human molars. The dentin surfaces were ground and bonding agents were applied and light cured. The thin-film bond strength test of the specimens was evaluated by the critical load at which the coated bonding agent failed and dentin appeared. The scratch mark sections were then observed under a scanning electron microscope. Indentation hardness was evaluated by the variation in depth under an applied load of 10gf. Data were compared by one-way ANOVA with the Scheffé’s post hoc multiple comparison test (p<0.05). In addition, thin-film bond strength and indentation hardness were analyzed using analysis of correlation and covariance. ResultsThe thin-film bond strength of two-step bonding agents were found to be significantly higher than that of one-step bonding agents with small standard deviations. Scratch marks consistently showed adhesive failure in the vicinity of the bonding agent/dentin interface. The indentation hardness showed a trend that two-step bonding agents have greater hardness than one-step bonding agents. A moderately significant correlation (r2=0.31) was found between thin-film bond strength and indentation hardness. SignificanceThin-film bond strength test is a valid and reliable means of evaluating bond strength in the vicinity of the adhesive interface and is more accurate than other methods currently in use. Further, the thin-film bond strength is influenced by the hardness of the cued bonding agent.

Effect of thermocycling on the durability of etch-and-rinse and self-etch adhesives on dentin.

The objective was to compare bond strengths of adhesives with/without thermocycling and to analyze the micromorphology of resindentin interfaces. Flat dentin surfaces were prepared and divided into eight groups to bond with four etch-and-rinse adhesives (Optibond FL, Adper Scotchbond Multi-Purpose, Optibond Solo Plus, and Single Bond 2) and four self-etch adhesives (Clearfil SE Bond, Adper SE Plus, Clearfil S(3) Bond and Adper Easy Bond). Specimens were further divided into two subgroups subjected for with/without thermocycling and then subjected to both micro-tensile test and resin-dentin interface evaluation. The results revealed that there were significant differences in bond strength between the groups with and without thermocycling for all etch-and-rinse groups and for the Adper Easy Bond self-etch group (p<0.01). Clearfil SE Bond demonstrated highly durable bond strengths. Furthermore, more silver ion uptake was observed at the resin-dentin interfaces for all etch-and-rinse adhesives and Adper SE Plus and Adper Easy Bond after thermocycling.

Chemical Adhesion of Polyalkenoate-based Adhesives to Hydroxyapatite.

To evaluate the chemical interaction between synthetic hydroxyapatite (HAp) and polyalkenoic acid copolymer- based (also known as Vitrebond copolymer [VCP]) adhesives. Six dentin adhesive formulations were used: 1) Adper Single Bond Plus (SB); 2) SB formulation without VCP (SBnoVCP); 3) Adper Easy Bond (EB); 4) EB formulation without VCP (EBnoVCP); 5) Scotchbond Universal adhesive (SBU); 6) SBU formulation without VCP (SBUnoVCP). Each adhesive was mixed with HAp, polymerized, and analyzed using FTIR and 13C/31P NMR spectroscopy. The FTIR spectra of SB+HAp indicated that the carbonyl group changed absorption wavenumber compared to that of SBnoVCP+HAp. 13C NMR analysis showed that the presence of methacrylated phosphoric esters in the EB and SBU formulations led to similar carbonyl resonance with or without VCP. 31P NMR revealed a resonance shift at 0.5 ppm for SB+HAp, EB+HAp and SBU+HAp spectra. In comparison with EB+HAp and SBU+HAp, a slight fade-out of the same resonance shift for EBnoVCP+HAp and SBUnoVCP+HAp was observed without completely disappearing, respectively, meaning that VCP might induce a modification of phosphorus moieties in addition to the ionic interaction between phosphate ester groups and HAp. Our data suggests that a chemical interaction occurred between VCP-containing adhesives and synthetic HAp.