Bonding Efficacy of Single-step Self-etch Systems to Sound Primary and Permanent Tooth Dentin

Evaluation of the Effects of Different Types of Resin Cement Systems on the Push-Out Bond Strength of the Fiber Post to Intracanal Dentin in Anterior Primary Teeth

Background

This study aimed to evaluate the effects of using three different resin cements on push-out bond strength (PBS) of fiber posts to root canal dentin of primary teeth.

Methods

Fifty primary canines were randomly divided into five experimental groups according to the type of the luting agent used for fiber post cementation after endodontic treatment and post space preparation as the following: Group 1: glass ionomer cement (GIC), Group 2: flowable resin composite, Group 3: etch and rinse (E&R) resin cement, Group 4: self-etch (SE) resin cement, Group 5: self-adhesive (SA) resin cement. The PBS values of the cemented fiber posts to root canals were measured. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's post hoc test.

Results

The highest mean PBS value was observed in Group 4 (SE resin cement), followed by Group 3 (E&R resin cement), and the lowest PBS value belonged to Group 1 (GIC), followed by Group 5 (p-values < 0.05). The mean PBS of Group 3 (E&R resin cement) was significantly higher than those of Groups 1 (GIC), 2 (flowable resin composite), and 5 (SA resin cement) (p-values < 0.05). However, no significant difference was found between the mean PBS of GIC and SA resin cement (p-value >0/05).

Conclusion

Using SE resin cement for fiber post cementation in primary anterior teeth showed the best results, followed by E&R resin cement. The lowest PBS was observed for GIC, followed by SA resin cement.

Comparison of the Pull-Out Resistance of Grossly Decayed Primary Anterior Teeth Restored With Two Different Intracanal Posts: An In Vitro Study

Background Severely damaged primary anterior teeth that require pulp therapy present a high risk of failure due to the loss of tooth substance, resulting from pre-existing decay and endodontic therapy. The ideal post material should have physical and mechanical properties similar to those of dentin. Another concern in restoring endodontically treated primary teeth is the need to find a material that can resorb similar to the natural tooth structure as a part of the exfoliation process, allowing normal eruption of permanent successors. Accordingly, there is no such material other than dentin itself. The introduction of biological dentin posts offers an excellent alternative for restoring such teeth. This study aimed to assess the effect of using dentin posts on the pull-out resistance of endodontically treated primary anterior teeth in comparison to glass fiber posts. Methodology A sample of 30 primary anterior teeth was collected from the outpatient clinic of the Pediatric Dentistry Department, Faculty of Dentistry, Damascus University. A total of 15 freshly extracted permanent teeth with single roots were also collected from the outpatient clinic of the Maxillofacial Surgery Department, Faculty of Dentistry, Damascus University. The roots of the permanent teeth were used to prepare 30 dentin posts using a CAD-CAM machine. After receiving proper endodontic treatment, the primary teeth were divided into two groups (15 teeth in each group). The first group was restored with dentin posts, and the second was restored with glass fiber posts, with the posts measuring 3 mm in length for both groups. Pull-out resistance testing was performed using a Testometric machine. Results The arithmetic mean of the forces applied in the glass fiber posts group was 153.2 ± 39.12 N, while the arithmetic mean of the forces applied in the dentin posts group was 156.7 ± 39.78 N. The data were analyzed at a 95% confidence interval using the independent Student's t-test. There were no statistically significant differences in pull-out resistance between the two groups. Conclusions Dentin posts showed a little increase in pull-out resistance than glass fiber posts. Therefore, the use of dentin posts as intracanal retention in primary anterior teeth is a successful alternative for composite posts.

Comparing the Fracture Resistance of Dentine Posts and Glass Fiber Posts in Primary Maxillary Incisors: An In Vitro Study

Background/purpose An ideal post material should have physical and mechanical properties similar to dentin. Another problem when restoring primary teeth that have undergone root canal treatment is the availability of materials that are resorbed in the exfoliation process in a manner similar to the structure of the natural tooth, allowing the normal eruption of a permanent tooth. This study aimed to evaluate the effect of using dentine posts on the fracture resistance of endodontically treated primary incisors in comparison to glass fiber posts. Materials and methods The study sample consisted of 30 extracted primary maxillary incisors that were randomly distributed into the following two groups: group I (experimental, n=15), which was restored with dentine posts; and group II (control, n=15), which was restored with glass fiber posts. Initially, 10 extracted single-root permanent teeth were collected to prepare 20 dentine posts using a computer-aided design-computer-aided manufacturing (CAD-CAM) machine. Then, the crowns of maxillary primary incisors were cut and the canals were prepared and filled. Then the preparation for a post was made using Gates Glidden drills, and the posts were placed with an extension of 3 mm within the canal in both groups, then the crown was built and the teeth were placed within acrylic cubes and subjected to 500 thermocycling. Fracture resistance was recorded using a Testometric machine (Rochdale, England: Testometric Co. Ltd.). Data were analyzed using an independent Student's t-test. Results The dentine posts group showed greater fracture resistance (246.3 N) than the glass fiber posts group (206.3 N). A statistically significant difference (p=0.004) was found between the two groups in favor of the dentine posts group. Conclusion Based on this in vitro study, the dentin posts used in restoring severely decayed primary maxillary incisors showed greater fracture resistance than glass fiber posts. Therefore, the use of dentin posts as intra-canal stabilizers in maxillary primary incisors is a good alternative for glass fiber posts.

Disinfection of caries-affected dentin using potassium titanyl phosphate laser, Rose bengal and Ozonated water on shear bond strength of deciduous teeth

AIM

To assess the efficacy of disinfection of caries-effected dentin (CAD) using KTP laser and different decontamination methods using ozonated water (OW), Rose Bengal photosensitizer (RBP), chlorhexidine (CHX), and Er, YAG laser on the shear bond strength (SBS) of adhesive resin bonded to deciduous teeth.

MATERIAL AND METHODS

A total of 50 extracted and radiographically verified carious primary molars were collected and scrutinized according to ICDAS criteria. Specimens were allocated randomly into five groups (n = 10) as per the type of CAD disinfectants. KTP laser, OW, RBP, CHX (control), and Er, YAG laser. After cavity sanitization, a resin adhesive (prime and bond NT) was smeared on the dentinal exterior followed by incremental composite filling. SBS evaluation was performed by employing specimens in the universal testing machine. The debonded surface was assessed under 40x magnification in a stereomicroscope to ascertain fracture mode. Statistical analysis was done by using the ANOVA and the Post Hoc Tukey multiple comparison tests (p < 0.05).

RESULTS

The highest SBS was exhibited by group 2 i.e., when OW was employed for CAD disinfection (10.25 ± 0.24 MPa). Whereas, the lowest SBS bond value was unveiled by samples in group 3 when RBP was applied for dentin surface sanitization (7.85 ± 0.59 MPa).CAD disinfection with KTP laser (8.25 ± 0.41 MPa), CHX (8.19 ± 0.73 MPa), and RBP displayed comparable bond values (p > 0.05).

CONCLUSION

Ozonated water and Er, YAG laser could be employed as cavity disinfectants in primary teeth as they demonstrated better shear bond strength without jeopardizing the adhesive binding capacity of restorative resins bonded to caries-affected dentin.

Comparison of Different Adhesive Systems on Bond Strength of Resin Composite Posts Placed in Primary Teeth

Background

This study evaluated the push-out bond strength of resin composite posts to the intracanal dentin in primary teeth using different adhesive systems.

Materials and Methods

In this experimental study, sixty-eight primary lateral incisors were randomly allocated in four groups (n = 17): Adper Single Bond 2 (ASB), Clearfil SE Bond 2 (CSE), G-Premio Bond in etch-and-rinse mode (GP-ER), and G-Premio Bond in the self-etch mode (GP-SE). The coronal one third of root canals was filled with resin composite. The push-out test was performed using a universal testing machine. ANOVA and LSD tests were used to analyze the data (P < 0.05).

Results

One-way ANOVA showed significant differences between the four groups in push-out bond strength (P = 0.002). The ASB and GP-SE groups showed lower and higher bond strengths, respectively. The failure mode distribution did not differ between the bonding agents used (P = 0.763). Adhesive and mixed failures were more frequent.

Conclusion

The GP-SE, GP-ER, and CSE exhibited significantly higher push-out bond strength than ASB. A universal adhesive system and 6th generation self-etch adhesives are recommended for use with resin composite posts in primary anterior teeth. Regarding the advantages of these bonding agents, such as fewer clinical steps, lower technical sensitivity, and easy application, they can be a good option for restoring primary teeth with short resin composite posts.

Comparative Evaluation of Microleakage of Flowable Composite Resin Using Etch and Rinse, Self-Etch Adhesive Systems, and Self-Adhesive Flowable Composite Resin in Class V Cavities: Confocal Laser Microscopic Study

The essential factor in determining the preservation of restoration is the marginal seal. Restoring cervical lesions with a resin composite has always been a challenge. Composite resins with various viscosities and different bonding systems are being researched to reduce the microleakage. Confocal laser scanning microscopy (CLSM) is the latest non-destructive technique for visualizing the microleakage. Objectives: To evaluate and compare the microleakage of Universal Flo composite resin (G-aenial) using etch and rinse adhesive system ER-2 steps (Adper Single Bond 2), self-etch adhesive system SE-1 step (G-Bond), and self-adhesive flowable composite resin (Constic) in Class V cavities using a confocal laser scanning microscope. Materials and Method: Class V cavities were prepared on 27 caries-free human extracted premolar teeth on the buccal and lingual surfaces with standardized dimensions of 2 mm height, width 4 mm, and a depth of 2 mm. After the cavity preparation, all teeth were randomly divided into three groups, namely Group-I: G-aenial Universal Flo with Single Bond 2 (n = 9 teeth); Group-II: G- aenial Universal Flo with G-Bond (n = 9 teeth), and Group-III: Constic (n = 9 teeth). The prepared and restored specimens were then subjected to thermocycling for 500 cycles in a water bath at 5 °C and 55 °C with a dwelling time of 30 s. The specimens were placed in 0.6% aqueous rhodamine dye for 48 h. Sectioning was carried out bucco-lingually and specimens were evaluated for microleakage under a confocal laser scanning microscope. Results: There was a significant difference (p = 0.009) in microleakage when comparing total etch and rinse, specifically between Adper Single Bond 2 ER-2 steps (fifth generation) and self-adhesive flowable composite resin, which is Constic. There was more microleakage in the self-etch bonding agent, particularly G-Bond, SE-1 step (seventh generation), when compared to ER-2 steps (fifth generation bonding agent); however, the results were not statistically significant (p = 0.468). The self-adhesive flowable composite resin showed more microleakage than SE-1 step and ER-2 steps. Conclusions: None of the adhesive systems tested were free from microleakage. However, less microleakage was observed in the total etch and rinse, especially Adper Single Bond 2 (ER-2 steps), than the self-etch adhesive system SE-1 step and self-adhesive flowable composite resin. Clinical significance: Constant research and technological advancements are taking place in dentin adhesives to improve the marginal seal. This has led to the evolution of total acid-etching dentin bonding agents termed as etch and rinse (ER)-2 steps (fifth generation dentin bonding agents) and self-etching (SE) 2 steps, and SE-1 step dentin bonding agents termed as the sixth and seventh generation bonding agents, respectively.

Comparative Evaluation of Microleakage of Bioactive, Ormocer, and Conventional GIC Restorative Materials in Primary Molars: An In Vitro Study Microleakage of Three Restorative Materials

This in vitro study aimed to evaluate and compare the microleakage of bioactive, ormocer, and conventional glass ionomer cement (GIC) restorative materials in primary molars. In this study, class V cavities were prepared on the buccal surface of 75 noncarious extracted primary molars. The teeth were then restored as per the groups assigned. Group A, group B, and group C used bioactive restorative materials, ormocer restorative materials, and conventional GIC restorative materials for restorations, respectively. The teeth were then thermocycled and subjected to microleakage analysis via dye penetration. The microleakage scores were compared for differences using the Kruskal–Wallis test. This was followed by multiple pairwise comparisons using the Dunn test. All testing was carried out using a ‘p’ value of <0.05. The percentage of samples showing microleakage score 0 depicting no dye penetration was highest for group A (56%) followed by group C (44%) and group B (12%). Statistical analysis revealed highest microleakage with group B, which was statistically significant ( $p$  < 0.05). Microleakage was evident in all the materials tested. The lowest microleakage was seen with bioactive restorative material.

Bond Strength of Self-Adhesive Flowable Composites and Glass Ionomer Cements to Primary Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies

Background: Conventional composites are largely used in pediatric restorative dentistry and demonstrate successful clinical outcomes. However, the need for simplification of operative steps in young or uncooperative children demands reliable alternatives. Therefore, the aim of the present systematic review and meta-analysis was to evaluate the in vitro bond strength of glass ionomer cements (GICs) and self-adhesive flowable composites (SFCs) on deciduous teeth. Methods: A comprehensive literature search according to the PRISMA checklist was manually and electronically performed by two independent reviewers through the following databases: MEDLINE/PubMed, Google Scholar, Scopus, and Embase, to include in vitro studies comparing GICs and SFCs bond strength values of restorations on primary teeth. In addition, three groups of meta-analyses were conducted using random-effects models. Results: Three articles meeting the inclusion criteria were selected and subjected to both qualitative and quantitative assessment. No statistically significant difference was found between SFC versus GIC; however, both groups significantly differed with conventional flowable composites (CFs). Conclusions: Despite the absence of significant difference in bond strength values, SFCs may be considered a valid alternative to GICs in the restoration of deciduous teeth, although CFs proved better in vitro performances.

Is the presence of 10-MDP associated to higher bonding performance for self-etching adhesive systems? A meta-analysis of in vitro studies

OBJECTIVE

The purpose of this systematic review and meta-analysis was to analyze the literature on the bond strength of self-etching (SE) adhesives containing 10-MDP or other acidic functional monomers, comparing the bonding performance of both compositions.

METHODS

This study is registered in PROSPERO (CRD42020175715) and it followed the PRISMA Statement. The literature search was performed in PubMed, Web of Science, SciELO, Scopus, LILACS, IBECS, and BBO from the starting coverage date through 30 June 2021. Study eligibility criteria consisted of in vitro studies that evaluated the bond strength (microtensile, microshear, tensile or shear testing) to sound dentin/enamel of a minimum of two distinct SE systems, with at least one material containing 10-MDP and one other being comprised of a distinct acidic composition. Statistical analyses were carried out with RevMan 5.3.5 and using random-effects models with the significance level at p < 0.05. Also, Bayesian network meta-analysis (NMA) was conducted using MetaInsight V3 tool.

RESULTS

From 740 relevant studies evaluated in full-text analysis, 210 were incorporated to the systematic review and 206 in meta-analysis. The majority of studies was classified as having medium risk of bias (56.7%), followed by low (35.2%) and high (8.1%) risk of bias. Data from a total of 64 adhesive systems were collected, which favored the 10-MDP-based group at both dentin (overall effect: 6.98; 95% CI: 5.61, 8.36; p < 0.00001) and enamel (overall effect: 2.79; 95% CI: 1.62, 3.96; p < 0.00001) substrates. Microtensile testing was more frequently used (73.4%) in the included studies. Adhesives based on 10-MDP showed greater bonding performance than adhesives comprised of monomers such as PENTA, 6-MHP, 4-META, 4-MET, pyrophosphate esters, mixed composition or monomers derived from sulfonic acid (p ≤ 0.01); whereas similar bond strength values were verified between 10-MDP-based materials and those containing PEM-F, acrylamide phosphates, 4-AET, MAC-10, or monomers derived from polyacrylic and phosphonic acids (p ≥ 0.05). Adhesives based on GPDM were the only ones that resulted in greater bonding potential than the 10-MDP-based group (p = 0.03). Dental bonds in dentin were favored with the application of 2-step 10-MDP-based adhesives; whereas in enamel the dental bonds were favored for both 2-steps versions of adhesives, regardless of the presence of 10-MDP. Indirect evidence from NMA revealed that 1-step 10-MDP-free and universal 10-MDP-free adhesives seemed to perform worst in dentin and enamel, respectively.

SIGNIFICANCE

Adhesives containing 10-MDP showed higher bonding performance than materials formulated with other acidic ingredients, although this result relied on the type of mechanical testing, type of the substrate, acidic composition of the adhesive, and the application category of the SE system. This review summarized the effects of the foregoing factors on the adhesion to dental substrates.

Etching time and bonding of adhesive systems to dentin of primary teeth: A systematic review and meta-analysis

BACKGROUND

Due to the chemical and morphological differences between primary vs. permanent teeth, the time reduction of the acid etching or acidic primer can result in higher values of bond strength.

AIM

To assess through a systematic review and meta-analysis the influence of the reducing etching (acid etching or acidic primer) time on the bond strength of adhesive systems to primary dentin.

DESIGN

A systematic search was carried out in 3 databases: PubMed, Web of Science and Scopus. Studies that evaluated the effect of reducing the etching time on the bond strength of adhesive systems to primary dentin were included. Meta-analyses were performed using a random-effects model, with subgroups for etch-and-rinse and self-etching adhesives, with a significance level of P < .05. The risk of bias and heterogeneity between studies (Cochrane and I2 tests) were assessed.

RESULTS

Eight studies were included in the systematic review and seven in the meta-analyses. The shortening etching time did not influence the immediate dentin bond strength for etch-and-rinse (Z = 0.07, P = .95) and self-etching adhesives (Z = 0.41, P = .69). After ageing, however, the shorting etching time improved the bond strength for etch-and-rinse adhesives (Z = 2.01, P = .04). All studies presented high bias risk.

CONCLUSIONS

Reducing the acid-etching time to primary dentin improves the long-term bond strength to this substrate.

Fracture Resistance of Three Post Types in the Restoration of Anterior Primary Teeth

Background:

Extensive restorative treatments of anterior primary teeth are challenging in pediatric dentistry.

Objective:

This study aimed to compare the fracture resistance of three post types for restoring the anterior primary teeth.

Methods:

This in-vitro study was carried out on 90 extracted maxillary anterior primary teeth with intact roots. They were randomly allocated into six groups to be restored with conventional composite resin post, X-tra fill composite resin post, Tetric N Ceram composite resin post, prefabricated glass fiber post with conventional composite build-up, prefabricated glass fiber post with X-tra fill composite build-up, and prefabricated glass fiber post with Tetric N Ceram composite build up. The samples were polished and placed in acrylic resin blocks with 1 mm of part of cervical root being out, thermocycled (×5000) and tested for fracture resistance. Intra-class correlation test, Kruskal-Wallis test and one-way ANOVA were used for statistical analyses (α=0.05).

Results:

The mean fracture resistance was significantly different among the six groups. It was the highest in prefabricated glass fiber post with conventional composite build-up (418.64 N), prefabricated glass fiber post with X-tra fill composite build-up (403.63 N) and prefabricated glass fiber post with Tetric N Ceram composite build up (361.63 N); and the lowest in Tetric N Ceram group (280.65 N). The groups were significantly different concerning the fracture strength and fracture state.

Conclusion:

Since the anterior teeth restored with prefabricated glass fiber posts were far more fracture resistant, and prefabricated glass fiber posts can be promisingly used for the restoration of anterior primary teeth.

An In Vitro Study of Effect of Beveling of Enamel on Microleakage and Shear Bond Strength of Adhesive Systems in Primary and Permanent Teeth

Aim and objectives

This in vitro study evaluated the effect of beveling of enamel on microleakage and shear bond strength of total-etch adhesive system: prime and bond NT and self-etch: adhesive system: XENO V in primary and permanent teeth.

Materials and methods

A total of 120 extracted human molars (60 primary and 60 permanent) were selected for the study. For microleakage examination, a sample size of 40 was chosen. Two rectangular slots of equal dimensions were prepared on the buccal surface of each tooth and a bevel was given on either of the slots. Each slot was restored using a composite resin with prior application of the selected bonding agent following which all the samples were soaked in 1% methylene blue dye for 48 hours. Then each tooth was sectioned horizontally and evaluated. The remaining 80 samples were subjected to the shear bond strength test. Class II cavities of standard dimension were prepared and bevel was given on each sample following which selected bonding agent was applied and restored with a composite resin. The specimens were placed in a fixture and the shear bond strength was determined using the universal testing machine.

Results

With respect to microleakage, the least was exhibited by beveled preparations in permanent teeth using the self-etch adhesive system and the highest shear bond strength was exhibited by beveled preparations using the total-etch adhesive system in permanent teeth.

Conclusion

Beveling of enamel improved the marginal integrity and shear bond strength of self-etch and total-etch adhesive systems in both primary and permanent teeth.

How to cite this article

Patanjali S, Arora A, et al. An In Vitro Study of Effect of Beveling of Enamel on Microleakage and Shear Bond Strength of Adhesive Systems in Primary and Permanent Teeth. Int J Clin Pediatr Dent 2019;12(3):205–210.

Shear Bond Strength of Self-Adhesive Flowable Composite, Conventional Flowable Composite and Resin-Modified Glass Ionomer Cement to Primary Dentin

Objectives:

This study aimed to compare the shear bond strength (SBS) of self-adhesive and conventional flowable composites and resin-modified glass-ionomer cement (RMGIC) to primary dentin.

Materials and Methods:

In this in vitro, experimental study, the buccal surface of 48 primary canine and first molar teeth was longitudinally sectioned to expose dentin. The teeth were randomly divided into three groups (n=16) of 37.5% phosphoric acid+ OptiBond+ Premise Flow composite (group 1), Vertise Flow composite (group 2) and RMGIC (group 3). A plastic cylindrical mold was placed on the exposed dentin and filled with restorative materials. The samples were then immersed in distilled water at 37°C for 24 hours, subjected to 1000 thermal cycles between 5–55°C and underwent SBS test. The mode of failure was determined under a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey’s test.

Results:

A significant difference was noted in SBS of the groups (P<0.05). The SBS of conventional flowable composite was significantly higher that of RMGIC and self-adhesive flowable composite (P<0.05). The difference in SBS of RMGIC and self-adhesive flowable composite was not significant (P>0.05). Failure at the dentin-restoration interface (adhesive failure) had the highest frequency in groups 1 and 2. The frequency of adhesive failure was 100% in group 3.

Conclusion:

Within the limitations of this study, the conventional flowable composite yielded the highest SBS to primary dentin. Self-adhesive flowable composite and RMGIC showed the lowest SBS with no significant difference with each other.

Are self-etch adhesives reliable for primary tooth dentin? A systematic review and meta-analysis

The purpose of this study was to systematically evaluate the dentin bond strength of etch-and-rinse and self-etch adhesives to primary teeth. In this study, PubMed, ISI (all databases), Scopus, and Cochrane Database were searched according to the selected keywords up to May 11, 2016. The full texts of published articles that appeared to meet the primary criteria for inclusion in this study were obtained. Due to the variation in the methods used, the studies were divided into 2 groups: Group 1 - studies that evaluated the micro-tensile bond strengths (MTBSs) of two-step etch-and-rinse adhesives and two-step self-etch adhesives and Group 2 - studies that evaluated the MTBSs of two-step etch-and-rinse adhesives and one-step self-etch adhesives. The initial search yielded 1447 publications. After a methodological assessment, 8 publications were selected. The results of this study showed that the MTBS of the etch-and-rinse adhesives and the two-step self-etch adhesives were similar (P = 0.34), and both were significantly higher than that of the one-step self-etch adhesive (P = 0.001). This meta-analysis showed that the application of two-step self-etch adhesives performs well when used for primary dentin and can be used to save time in pediatric dentistry.

Evaluation of the effect of different post materials and adhesive systems on the bonding strength of short-post technique for primary teeth

BACKGROUND

The most important process in treating grossly decayed teeth, including decay in the pulp, is the ability to hold a retainer in for a short time.

AIM

The aim of this study was to investigate the bond strengths of different adhesive systems and post materials on primary teeth.

DESIGN

One hundred and twenty extracted maxillar primary central incisor teeth were randomly divided into two main groups (total-etch and self-etch adhesive systems) and five subgroups (1: control-nanohybrid composite resin, 2: pre-impregnated glass fiber, 3: unsaturated glass fiber, 4: polyethylene fiber, 5: short-fiber reinforced composite resin). The push-out test was performed using a universal testing machine with a crosshead speed of 0.5 mm/min.

RESULTS

No statistically significant difference was detected between the two different adhesive systems and five different materials in terms of the maximum values measured for fractures in the specimens when both the adhesive materials and the short-post materials were evaluated separately (P > 0.05). However, as a result of multiple comparisons made, it was found that statistical differences between the groups applying the total-etch adhesive system occurred in Groups 3 and 5. The highest push-out test values were measured in Group 5 and Group 1, and the lowest value in Group 3. Although the fracture type distribution in the total-etch adhesive system groups was not statistically different based on the material used (χ²  = 11,865; P = 0.309), the self-etch adhesive systems did show differences (χ²  = 28,463; P < 0.001). Both the total-etch and the self-etch adhesive system groups showed mostly adhesive failures.

CONCLUSION

The fiber-reinforced and nanohybrid composite resin had higher values in the short-post technique, and there was no significant difference between the different fiber posts.

Rubbing time and bonding performance of one-step adhesives to primary enamel and dentin

Objectives:

This study investigated whether increasing the concentration of acidic monomers in one-step adhesives would allow reducing their application time without interfering with the bonding ability to primary enamel and dentin.

Material and methods:

Experimental one-step self-etch adhesives were formulated with 5 wt% (AD5), 20 wt% (AD20), or 35 wt% (AD35) acidic monomer. The adhesives were applied using rubbing motion for 5, 10, or 20 s. Bond strengths to primary enamel and dentin were tested under shear stress. A commercial etch-and-rinse adhesive (Single Bond 2; 3M ESPE) served as reference. Scanning electron microscopy was used to observe the morphology of bonded interfaces. Data were analysed at p<0.05.

Results:

In enamel, AD35 had higher bond strength when rubbed for at least 10 s, while application for 5 s generated lower bond strength. In dentin, increased acidic monomer improved bonding only for 20 s rubbing time. The etch-and-rinse adhesive yielded higher bond strength to enamel and similar bonding to dentin as compared with the self-etch adhesives. The adhesive layer was thicker and more irregular for the etch-and-rinse material, with no appreciable differences among the self-etch systems.

Conclusion:

Overall, increasing the acidic monomer concentration only led to an increase in bond strength to enamel when the rubbing time was at least 10 s. In dentin, despite the increase in bond strength with longer rubbing times, the results favoured the experimental adhesives compared to the conventional adhesive. Reduced rubbing time of self-etch adhesives should be avoided in the clinical setup.

Self-etch or etch-and-rinse mode did not affect the microshear bond strength of a universal adhesive to primary dentin

This study evaluated the microshear bond strength (µSBS) of resin composite to primary dentin using a universal adhesive in etchand-rinse mode or self-etch mode. Flat ground dentin surfaces were created on forty extracted human primary incisors and randomly assigned into four groups (n=10): Adper Single Bond II (ASB), Clearfil SE Bond (CSE), Single Bond Universal etch-and-rinse (SBUER) and Single Bond Universal self-etch (SBU-SE). Adhesive was applied on the dentin surface, which was subsequently bonded with a resin composite. The µSBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The ASB group generated a lower mean µSBS (19.1±3.4 MPa) than those of the other groups [SBU-ER (24.3±2.7 MPa), SBU-SE (25.1±2.4 MPa), and CSE (25.3±2.7 MPa)]. Adhesive failure was the most common failure mode in each group. In conclusion, SBU used in etch-and-rinse or self-etch mode resulted in similar bond strength to primary dentin.

Randomized Clinical Trial of Composite Restorations in Primary Teeth: Effect of Adhesive System after Three Years

The purpose of this study was to assess the clinical performance of composite restorations placed with different adhesive systems in primary teeth. In 32 patients, 128 composite restorations were placed using a split-mouth design as follows (4 groups/patient): three-step etch-and-rinse (Group 1), two-step etch-and-rinse (Group 2), two-step self-etch (Group 3), and one-step self-etch (Group 4). The restorations were clinically evaluated at baseline and at 6, 18, and 36 months according to the FDI criteria. There was no significant difference between the adhesive systems in retention of the restorations (p > 0.05). Over time, there was a statistically significant decrease in marginal adaptation in all groups, whereas surface and marginal staining significantly increased in Groups 3 and 4 (p < 0.05). The etch-and-rinse adhesive systems resulted in better marginal adaptation than the self-etch adhesive systems (p < 0.05). It was concluded that preetching of the primary enamel might help improve the clinical performance of the self-etch adhesive systems in primary teeth.

Effect of endodontic sealers on bond strength of restorative systems to primary tooth pulp chamber

Background/purpose

Although current literature suggests that root canal sealers affect the bonding ability of restorative systems to pulp chamber dentin of permanent teeth, primary teeth have not been investigated. This study intended to evaluate the microtensile bond strength (μTBS) of three restorative systems to pulp chamber dentin in primary teeth and to determine the effect of two different root canal sealers on the μTBS.

Materials and methods

Ninety primary molars were used in this study. The teeth were randomly divided into three main groups according to canal sealers: (1) control (without sealer); (2) Metapex; and (3) zinc-oxide eugenol. The main groups were further divided into three subgroups depending on the coronal restorative system: (1) compomer (Prime Bond NT + Dyract EXTRA); (2) composite (Clearfil Tri-S Bond + Clearfil Photo Posterior); and (3) resin-modified glass ionomer (Fuji II LC). After restoration, the buccal wall of the pulp chamber was sectioned to obtain sticks (1 mm × 1 mm). The μTBS was then measured. Data were analyzed with two-way analysis of variance, followed by a posthoc test. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.

Results

In the control group, a significant difference was observed only for the μTBS of the composite (P < 0.05). Compared with the control groups, Metapex and zinc-oxide eugenol significantly reduced the μTBS of restorative systems (P < 0.05).

Conclusion

Composite materials seemed to bond to pulp chamber dentin in primary teeth with a higher strength than compomer and resin-modified glass ionomer. Metapex and zinc-oxide eugenol canal filling materials reduced the bond strength of all three restorative systems.

Assessment of Microleakage of a Composite Resin Restoration in Primary Teeth Following Class III Cavity Preparation Using Er, Cr: YSGG laser: An In Vitro Study

Introduction: Marginal seal integrity is important for a successful adhesive dental restoration. Alterations caused by laser irradiation in the enamel and dentin surface can affect the marginal integrity of adhesive restorations. The aim of this study was to evaluate the microleakage of a composite resin restoration in primary teeth following laser irradiation of enamel and dentin. Methods: Forty freshly extracted sound human primary maxillary and mandibular anterior teeth were used in this study. The teeth were randomly divided into two groups (I and II), with 20 teeth in each. In group I, proximal cavities (Class III) were prepared using an airotor hand -piece and diamond bur. The cavities were etched for 15 seconds with 35% phosphoric acid gel, rinsed with water for 15 seconds, air dried and a bonding agent was applied onto the cavity surfaces and light cured for 20 seconds. The cavities were restored with composite resin and light cured for 40 seconds. In group II, proximal (Class III) cavities were prepared using Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) (Er,Cr:YSGG) (Biolaseiplus, wave length 2.78 μm). The cavity was then rinsed, air dried and without etching, a bonding agent was applied and light cured for 20 seconds. The cavities were restored in the same manner as that of group I. The treated teeth were mounted on acrylic resin blocks and were subjected to a thermocycling regimen. Following, the teeth were immersed in 2% methylene blue for 24 hours. The teeth were sectioned longitudinally in a bucco-lingual direction using a diamond disc at slow speed. The sections of all the groups were examined under a stereomicroscope for micro-leakage. Results: The mean scores for microleakage in group I was 1.95 ± 1.31 and in group II it was 1.4 ± 1.27. There was no significant difference between the two groups (P = 0.882). Conclusion: No significant difference in microleakage was noticed between the composite resin bonded to lased enamel and dentin and the teeth preparedwith conventional method.

Comparative evaluation of shear bond strength of three flowable compomers on enamel of primary teeth: An in-vitro study

Background

The aim of the present study was to determine Shear bond strength (SBS) of different flowable compomers on the enamel surface of primary teeth. The null hypothesis to be tested was that none of the flowable compomer would differ significantly from the other two with respect to SBS. As a result, the tested materials that have the easiest application on child patient is preferred.

Material and Methods

Sixty newly extracted non carious primary molars were selected. The buccal surface was cleaned and polished to obtain a flat enamel surface. The specimens were randomly divided into three groups of 20 teeth each, based on the flowable compomers applied, as follows: group I: Dyract Flow® (Dentsply, Konstanz, Germany); group II: Twinky Star Flow® (Voco, Cuxhaven, Germany); and group III: R&D Series Nova Compomer Flow® (Imicryl, Konya, Turkey).

Results

SBS in group II (6.78± 0.45 MPa) were significantly lower than groups I and III (8.30 ± 0.29 and 8.43 ± 0.66 MPa, respectively) (P<.001). No significant difference was found between groups I and III (P<.05).

Conclusions

Significant differences existed between the SBS of the groups. Therefore, the null hypothesis was rejected. Flowable compomers can provide adequate SBS with self-etching system at restoration of primary teeth. Thus, successful restorations in pediatric patients can be done in a practical way.

Key words:Flowable compomer, primary teeth, shear bond strength.

Fracture resistance of three different posts in restoration of severely damaged primary anterior teeth: An in vitro study

Background:

Restoration of anterior primary teeth with severe caries lesion is a big challenge. The aim of this study was to compare the fracture resistance of three types of post, including composite resin, customized quartz fiber and prefabricated glass fiber in restoration of severely damaged primary anterior teeth.

Materials and Methods:

Sixty extracted human primary maxillary incisors were randomly divided into three groups: Group 1: Customized quartz fiber post, Group 2: Composite post and Group 3: Prefabricated glass fiber post. Due to the effect of bonded area on the fracture resistance, the bonded surface of each sample was measured 1 mm above cementoenamel junction. An increasing force was subjected with a crosshead speed of 0.5 mm/min by a universal testing machine until fracture occurred, and the failure mode was assessed afterwards. Data were analyzed using One-way analysis of variance and Kruskal–Wallis tests. The level of significance was considered at P < 0.05.

Results:

The mean fracture resistance values of three groups were 343.28 N, 278.70 N and 284.76 N, respectively. Although customized quartz fiber post showed the greatest fracture resistance, statistical analysis revealed no significant difference between groups (P = 0.21). The mean fracture strength values of three groups were 12.82 N/mm^–2, 11.93 N/mm^–2 and 11.31 N/mm^–2, respectively; however, the differences were not statistically significant (P = 0.72). Favorable failure mode was more frequent in all groups (P = 0.12).

Conclusion:

Within the limitations of this study, it can be concluded that all three types of studied posts can be successfully used to restore badly destructed primary anterior teeth.

Tubule density and diameter in coronal dentin from primary and permanent human teeth

This study compared dentinal tubule density and diameter of human primary and permanent teeth at different depths of the coronal dentin. Crowns of eight primary second molars and eight permanent third molars were serially sectioned into three disks of ~0.5 mm thickness (superficial, middle, and deep layers), perpendicular to the long axis. Tubule density and diameter were evaluated in 2,000× and 3,000× magnifications by scanning electron microscopy. Data obtained were subjected to two-way repeated measures ANOVA and Tukey's post hoc test (α = 0.05). Tubule density was greater in primary teeth compared with permanent ones, regardless of depth (primary: 124,329 ± 43,594 mm2; permanent: 45,972 ± 21,098 mm2). In general, the tubule density increased as the dentin depth increased, except to the superficial and middle layers from permanent teeth. Tubule diameter was larger in the dentin layer close to the pulp chamber (superficial: 2.4 ± 0.07 μm; middle: 3.70 ± 0.06 μm; deep: 4.28 ± 0.04 μm). No difference was observed between primary (3.48 ± 0.81 μm) and permanent teeth (3.47 ± 0.73 μm). The tubule diameter increases as the dentin depth increases for primary and permanent teeth; however, the tubule density is higher in primary teeth.

Resistance to degradation of resin-dentin bonds produced by one-step self-etch adhesives

The objective of this article is to evaluate the resistance to degradation of resin-dentin bonds formed with three one-step adhesives. Flat, mid-coronal dentin surfaces were bonded with the self-etching adhesives [Tokuyama Bond Force (TBF), One Up Bond F Plus (OUB), and G-Bond (GB)]. The bonded teeth were subjected to fatigue loading, chemical degradation, and stored in distilled water for four time periods (up to 12 months). Specimens were tested for microtensile bond strength and microleakage. Fractographic analysis was performed by scanning electron microscopy. Bonded interfaces were examined by light microscopy using Masson's trichrome staining. An atomic force microscope was employed to analyze phase separation and surface nanoroughness (Ra) at the polymers. Vickers microhardness and the degree of the conversion (DC) were also determined. ANOVA and multiple comparisons tests were performed. Bond strength significantly decreased after the chemical challenge, but not after load cycling. Aging decreased bond strength after 6 months in TBF and GB, in OUB after 12 months. An increase of the nonresin protected collagen zone occurred in all groups, after storing. TBF showed the highest roughness, microhardness, and DC values, and GB showed the lowest. Mild self-etch one-step adhesives (TBF/OUB) showed a higher degree of cure, lower hydrophilicity, and major resistance to degradation of resin-dentin bonds when compared to highly acidic self-etching adhesive (GB).

Comparative evaluation of the effect of different bonding agents on the ultramorphology of primary tooth dentin and the resin dentin interface

Aim:

To analyze and compare the changes in the ultramorphology of dentin in primary teeth using different bonding agents and to study the resin/dentin interface produced by them.

Materials and Methods:

Occlusal surfaces of 50 extracted human deciduous teeth were grounded to expose the dentin. The teeth were divided into two groups (A) For viewing surface morphology- 18 teeth divided into four groups: (a) for viewing dentinal morphology (3 teeth), (b) Scotchbond multi-purpose (5 teeth), (c) Adhe SE (5 teeth), (d) Futurabond (5 teeth). (B) For viewing interfacial morphology- 32 teeth divided into four groups with 8 teeth each: (a) Scotch Bond Multipurpose (3M, ESPE),), (b) Adhe Se (Vivadent), (c) Optibond All-in-One (Kerr), (d) Futurabond NR (VOCO, Cuxhaven, Germany). The adhesives were applied to each group following the manufacturer's instruction. All the samples were then prepared for viewing under SEM.

Results:

The photographs were graded using a four-step (0-3) scale method proposed by Ferrari et al. For Scotchbond, 12 (75%) were graded as 2 Grade 3 was observed in only 1 observation in the entire lot of materials. The results obtained for Adhe SE and Optibond AIO were similar, i.e. in 5 (31.25%) observations each the scores were 0 and in 11 (68.75%) observations each the scores were 1. In case of Futurabond, 3 (18.75%) observations were graded as 0 and 13 (81.25%) were graded as 1, thus showing a mean score of 0.81±0.40.

Conclusion:

Three- step bonding agent results in the complete removal of smear layer. While the self- etch approach is not efficient in removing the smear layer and opening of the dentinal tubules. The longest resin tags with lateral branches were seen in two groups- Scotch bond multipurpose and Optibond FL.

Degradation of resin-dentin bonds of etch-and-rinse adhesive system to primary and permanent teeth

The aim of this in vitro study was to compare the degradation of resin-dentin bonds of an etch-and-rinse adhesive system to primary and permanent teeth. Flat superficial coronal dentin surfaces from 5 primary second molars and 5 permanent third molars were etched with phosphoric acid and bonded with an adhesive system (Adper Single Bond 2, 3M ESPE). Blocks of resin composite (Z250, 3M ESPE) were built up and the teeth sectioned to produce bonded sticks with a 0.8 mm² cross-sectional area. The sticks of each tooth were randomly divided and assigned to be subjected to microtensile testing immediately (24 h) or after aging by water storage (6 months). Data were analyzed by two-way repeated measures ANOVA and Tukey post hoc test (α = 0.05). Failure mode was evaluated using a stereomicroscope (400×). Microtensile values significantly decreased after the 6 months aging, independent of the dentin substrate. In 24 h, the values obtained to primary dentin were lower compared with permanent dentin. This difference was not maintained after aging. Adhesive/mixed failure was predominant in all experimental groups. In conclusion, degradation of resin-dentin bonds of the etch-and-rinse adhesive system occurred after 6 months of water storage; however, the reduction in bond strength values was higher for permanent teeth.

Chlorhexidine does not increase immediate bond strength of etch-and-rinse adhesive to caries-affected dentin of primary and permanent teeth

The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on immediate bond strength of etch-and-rinse adhesive to sound (SD) and caries-affected (CAD) primary dentin compared with permanent dentin. Flat dentin surfaces from 20 primary molars (Pri) and 20 permanent molars (Perm) were assigned to 8 experimental groups (n=5) according to tooth type (Pri or Perm), dentin condition (SD or CAD - pH-cycling for 14 days) and treatment (control - C or 60 s application of 2% CHX solution after acid etching - CHX). The bonding system (Adper Single Bond 2) was applied according to manufacturer's instructions followed by resin composite application (Filtek Z250). After 24 h water storage, specimens with cross-section area of 0.8 mm² were prepared for being tested under microtensile test (1 mm/min). Data were submitted to ANOVA and Tukey's post hoc test (α=0.05). Failure mode was evaluated using a stereomicroscope at ×400. Treatment with CHX did not result in higher bond strength values than no pre-treatment (C groups), independently of tooth type. Primary teeth and caries-affected dentin showed significantly lower (p<0.05) bond strength means compared with permanent teeth and sound dentin, respectively. Predominance of adhesive/mixed failure was observed for all groups. CHX did not influence the immediate bond strength to sound or caries-affected dentin of primary and permanent teeth.

Imperfect hybrid layers created by an aggressive one-step self-etch adhesive in primary dentin are amendable to biomimetic remineralization in vitro

Degradation of hybrid layers created in primary dentin occurs as early as 6 months in vivo. Biomimetic remineralization utilizes "bottom-up" nanotechnology principles for interfibrillar and intrafibrillar remineralization of collagen matrices. This study examined whether imperfect hybrid layers created in primary dentin can be remineralized. Coronal dentin surfaces were prepared from extracted primary molars and bonded using Adper Prompt L-Pop and a composite. One-millimeter-thick specimen slabs of the resin-dentin interface were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs to mimic the sequestration and templating functions of dentin noncollagenous proteins. Specimens were retrieved after 1-6 months. Confocal laser scanning microscopy was used for evaluating the permeability of hybrid layers to Rhodamine B. Transmission electron microscopy was used to examine the status of remineralization within hybrid layers. Remineralization at different locations of the hybrid layers corresponded with quenching of fluorescence within similar locations of those hybrid layers. Remineralization was predominantly intrafibrillar in nature as interfibrillar spaces were filled with adhesive resin. Biomimetic remineralization of imperfect hybrid layers in primary human dentin is a potential means for preserving bond integrity. The success of the current proof-of-concept, laterally diffusing remineralization protocol warrants development of a clinically applicable biomimetic remineralization delivery system.

Do the origins of primary teeth affect the bond strength of a self-etching adhesive system to dentin?

The aim of this in vitro study was to evaluate the tensile bond strength of a self-etching adhesive system to three different dentinal substrates. Primary molar teeth that had been recently exfoliated (RE), with unknown time of exfoliation (UT), and extracted due to prolonged retention (PR) were used for this investigation. Ten primary molar teeth of each group were cut in the middle following the mesio-distal direction, creating a total of twenty specimens per group. The specimens were included in acrylic resin and had a flat dentin surface exposed. The self-etching adhesive system was applied to this surface and a 3-millimeter high cone with diameter of 2 mm in the adhesion area was constructed using composite resin. The specimens were stored in distilled water at 37ºC for 24 hours. Fifteen specimens of each substrate were used for the tensile bond test (n = 15) and 5 had the interface analyzed by scanning electron microscopy (SEM). The data was examined by one-way ANOVA and presented no significant differences between groups (p = 0.5787). The mean values obtained for RE, UT and PR were 18.39 ± 9.70, 19.41 ± 7.80, and 23.30 ± 9.37 MPa, respectively. Any dentinal substrates of primary teeth studied are safe for tensile bond strength tests with adhesive systems.

Primary dentin etching time, bond strength and ultra-structure characterization of dentin surfaces

OBJECTIVES

To evaluate the effect of shortening the etching time on roughness, microhardness and bond strength of three adhesive systems to primary tooth dentin.

METHODS

Flat dentin surfaces from primary molars were randomly assigned to six experimental groups. Three different adhesive systems were used: an etch-and-rinse adhesive (Single Bond), a two-step self-etching (Clearfil SE Bond), and a one-step self-etching (One-Up Bond F) adhesive. In half of the specimens, the recommended etching time was used, in the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and stored in a humid environment for 24h at 37 degrees C. Specimens were sectioned into 1mm(2) beams and tested for microtensile bond strength (MTBS). Debonded surfaces were analyzed by scanning electron microscopy (SEM). Additional surfaces were conditioned for microhardness measurements (KHN) and for atomic force microscopy (AFM) analysis. Intertubular and total surface roughness (Ra) were recorded. Results were analyzed with ANOVA and Student-Newman-Keuls tests (P<0.05).

RESULTS

Single Bond and Clearfil SE Bond showed higher MTBS than One-Up Bond F. Bond strength and intertubular roughness increased when Single Bond and One-Up Bond F were used with a reduced etching time. For Clearfil SE Bond no differences in MTBS were detected when reducing the etching time. The application of phosphoric acid, Clearfil SE Bond primer and One-Up Bond F decreases dentin microhardness.

CONCLUSIONS

Shortening One-Up Bond F application time and reducing the etching time of phosphoric acid to one-half of the manufacturer's recommended etching time when using Single Bond are recommended when bonding to primary dentin.

Evaluation of the furcation area permeability of deciduous molars treated by neodymium:yttrium-aluminum-garnet laser or adhesive

The purpose of this in vitro study was to compare the effects of a self-etch adhesive system and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser application on the dentinal permeability of the furcation area of primary molars. After endodontic access, 39 extracted human deciduous molars were divided into three groups: control group (CG), no treatment; adhesive group (AG), self-etching adhesive was applied to the furcation area; laser group (LG), specimens were irradiated with Nd:YAG laser. To evaluate dentin permeability of the furcation area, we immersed the specimens in 0.5 % methylene blue dye for 4 h. Then, they were longitudinally sectioned into two halves and photographed. The images were analyzed by two qualified evaluators using TpsDig software to calculate the percentage of the dye penetration area in comparison with the total furcation area. Additional analyses by scanning electron microscopy (SEM) were performed. The analysis of variance (ANOVA), complemented by Student's t-test, showed that mean dye penetration in the LG was statistically significant lower than that in all the other groups (P < 0.05). The SEM analysis showed mostly dentinal tubules obliterated by smear layer in the CG; in the AG the smear layer was modified by the adhesive, and, in the LG, melted surfaces were observed. It can be concluded that the Nd:YAG laser was capable of reducing the dentinal permeability of the furcation area of deciduous molars.

Differential bonds degradation of two resin-modified glass-ionomer cements in primary and permanent teeth

OBJECTIVES

To evaluate the effect of chemical degradation on bond strength of resin-modified glass-ionomer cements bonded to primary and permanent dentin.

METHODS

Class I cavities of permanent and primary extracted human molars were restored with two resin-modified glass-ionomer cements: Fuji II LC and Vitremer, and stored in water for 24h. Half samples were immersed in 10% NaOCl aqueous solution for 5h. Teeth were sectioned into beams and tested for microtensile bond strengths. Results were analyzed with multiple ANOVA and Tukey's tests (p<0.05). Analysis of debonded surfaces was performed by SEM.

RESULTS

24h bond strengths for Vitremer and Fuji II LC were similar. For Fuji II, bond strength values were higher for primary than for permanent dentin. Vitremer bond strength was similar for both. Chemical degradation did not affect Fuji II LC bond strength to dentin. However, decreases in bond strength were found for Vitremer groups after NaOCl immersion. Signs of glass ionomer-dentin interaction were evident by SEM analysis for Fuji II LC specimens.

CONCLUSIONS

Vitremer and Fuji II presented similar bond strength at 24. Vitremer dentin bonds were prone to chemical degradation. Fuji II LC-dentin bonds showed typical features of glass-ionomer dentin interaction at the bonded interfaces, and were resistant to in vitro degradation.

Effect of acid etching time on bond strength of an etch-and-rinse adhesive to primary tooth dentine affected by amelogenesis imperfecta

BACKGROUND

Dentine affected by amelogenesis imperfecta (AI) is histologically altered following loss of the hypoplastic enamel and becomes hypermineralized, which would make bonding less predictable.

AIM

This study examined the effect of etching time on the microtensile bond strength (microTBS) to AI-affected primary dentine.

DESIGN

Flat coronal dentine surface was obtained from extracted AI-affected and noncarious primary molars. Teeth were etched either for 15 or for 30 s using 34% phosphoric acid. Prime & Bond NT (Dentsply De Trey), an etch-and-rinse adhesive, was applied to dentine surfaces, air-dried and light-cured, followed by composite build-ups. The bonded teeth were sectioned into beams of 0.8 mm(2) and stressed to failure under tension. Representative fractured beams from each group were examined under scanning electron microscopy.

RESULTS

The extended etching time had an adverse effect on the microTBS for the normal dentine, while no significant difference was found for AI-affected dentine. When the AI-affected dentine was etched for 30 s, the fracture occurred in the demineralized dentine at the base of the hybrid layer.

CONCLUSION

Bonding to AI-affected dentine compromised the bonding of the etch-and-rinse adhesive. The bonding could not be improved by increasing etching time.

Tensile bond strength of different adhesive systems to enamel and dentin

The aim of this study was to assess the tensile bond strength of four adhesive systems to enamel and dentin: Clearfil Liner Bond 2V - C, Prime&Bond NT/NRC - PB, Single Bond - SB and All Bond 2 -AB. For such purpose, 40 sound human molars were selected. Crowns were bisected in a mesiodistal direction and each half was ground until flat enamel (E) or dentin (D) surfaces were obtained. A total of 80 specimens were randomly assigned to 4 groups (n=20, 10 in enamel and 10 in dentin). After surface treatment, a composite resin (Z250; 3M) cone was prepared using a split Teflon® matrix. Bond strength was tested in an universal testing machine (0.5 mm/min). Bond strength means in MPa were: C - E: 18.66 (±2.67) and D: 21.62 (±5.29); PB - E: 18.13 (±2.96) and D: 3.19 (±1.40); SB - E: 20.06 (±6.11) and D: 16.95 (±2.57); AB - E: 18.20 (±3.94) and D: 15.94 (±4.72). Statistical analysis of data by two-way ANOVA showed that C presented the best results followed by SB. In conclusion, among the tested materials, Clearfil Liner Bond 2V self-etching primer adhesive syetem had the best performance. The substrate type influenced bond strength, being higher to enamel.