Is the bonding of self-adhesive cement sensitive to root region and curing mode?

Influence of Battery Levels in Cordless LED Light-curing Units on Properties of Resin Cement and Glass Fiber Post Retention

PURPOSE

This study aimed to assess the impact of battery levels in single-peak and multi-peak light-curing units (LCUs) on irradiance, and their effects on glass fiber post push-out bond strength to root dentin and the degree of conversion of dual-cure universal resin cement.

METHODS AND MATERIALS

Sixty bovine roots underwent endodontic treatment and were randomly distributed into 6 groups (n=10), formed by combining two LCUs (single-peak and multipeak) and three battery levels (100%, 50%, and 10%). A spectrophotometer measured irradiance (mW/ cm2) and spectral irradiance (mW/cm2/nm). Push-out bond strength (PBS) tests occurred at three root regions (cervical, middle, and apical), with optical and scanning electron microscopy for failure mode analysis. Degree of conversion (DC) was evaluated across the root regions. Data were analyzed using two-way repeated measures ANOVA and the Tukey HSD test. The Fisher exact test verified failure modes (α=0.05).

RESULTS

As multipeak LCU battery levels decreased, emitted irradiance also diminished, with notable PBS reductions in the apical thirds. Failure modes were influenced by different conditions, primarily exhibiting mixed modes. Battery levels significantly impacted DC in the multipeak LCU, particularly in the cervical region, while the single-peak LCU exhibited DC reduction at the 10% battery level in the cervical region.

CONCLUSIONS

Emitted irradiance, resin cement DC, and glass fiber post bond strength to root dentin may be influenced by varying cordless LCUs and battery levels.

Shelf life effects on the bond strength and microhardness of self-adhesive resin cements

Background

Among the main advantages of self-adhesive resin cements comprise good aesthetics, strong restoration-tooth bond and biocompatibility. However, some disadvantages, such as high viscosity level, color limitation and short shelf life should be mentioned. Thus, the aim of the current study was to assess bond strength between fiberglass post and root dentin in teeth subjected to self-adhesive resin cements with expired shelf life and hardness.

Material and Methods

Sixty (60) single-rooted human teeth were sectioned and divided into 2 groups of different cements: U200 3M and MaxCem Elite Kerr. Each group was divided into 3 subgroups, based on self-adhesive resin cements' shelf life, namely: Within the use-time recommended by the manufacturer or no expiration date; 6 months after opening the aluminum blister; 12 months after opening the aluminum blister. Bond strength was measured through push-out test conducted in universal testing machine; fracture pattern was analyzed, and microhardness was investigated through Knoop test, based on hardness readings. Data were subjected to Shapiro-Wilk normality test; nonparametric test was applied to hardness data, whereas parametric test was applied to bond strength data. Hardness data were subjected to Kruskal-Wallis test, whereas bond strength data were subjected to analysis of variance, which was followed by Tukey test; both tests were conducted at 5% significance level (α = 0.05).

Results

There was no statistically significant difference in knoop hardness values recorded for the material / time / root thirds combination (p=0.483). There was no statistically significant difference in bond strength values recorded for the Material / Time / Thirds combination (p=0.237).

Conclusions

It was possible concluding that shelf life did not influence material's hardness and bond strength. Key words:Dental cements, Resin Cements, Shelf Life of Products.

Evaluating the use of self-conditioning adhesive combined with dual curing resin cement as an endodontic sealer: An in vitro study

Objectives

To compare infiltration, sealing and microleakage in root dentin with a self-conditioning adhesive system combined with dual curing resin (resin-based cement) to a conventional epoxy-resin-based sealer using confocal microscopy imaging.

Methods

26 roots were enlarged and disinfected. Dentin tubules of 24 teeth were labelled with a red fluorophore (Rhodamine B) (two samples served as controls). Root canal samples were sealed in group AH (n = 11) with a conventional sealer (AH Plus Root Canal Sealer, Dentsply DeTrey) and in group RC (n = 11) with a resin-based cement (Parabond combined with Paracore, Coltène). Roots were then sectioned horizontally and immersed in H2O2 to remove the Rhodamine B not fixed by the sealers. The empty dentin spaces were labeled with a green fluorophore (Fluorescein) enabling the evaluation of infiltration as well as microleakage by confocal microscopy. Two additional samples were fractured in vertical direction for observation under SEM.

Results

Group RC presented significantly more infiltration in the middle third than in the middle and apical thirds of group AH. Microleakage was significantly higher in group AH than in group RC. SEM images revealed more dentin plugs and a homogenous resin layer in group RC in contrast to group AH.

Conclusion

The resin-based cement revealed promising outcomes compared to a traditional epoxy resin based sealer.

Influence of different adhesion strategies on glass fiber post retention

Background

Failures in glass fiber post (GFP) retention may be associated with low adhesion achieved in root dentin.

Material and Methods

55 single-rooted premolars were endodontically treated and distributed according to different adhesion strategies (n=11): G1: RelyX ARC (3M ESPE; etch-rinse strategy); G2: Relyx Ultimate (3M ESPE; etch-rinse strategy); G3: AllCem (FGM; etch-rinse strategy); G4: Relyx Ultimate (3M ESPE; self-etching strategy); G5: RelyX U200 (3M ESPE; self-adhesive strategy). For Bonding Strength (BS) analysis, the roots were sectioned in slices (1.0mm thickness) corresponding to each root third and submitted to push-out test. The type of failure was assessed by scanning electron microscopy (SEM).

Results

The highest BS averages were found in G2 and G3. However, in the middle and apical root thirds, G3 showed statistically similar results to G4 and G5. In the cervical and middle third, G1 was statistically similar to G4 and G5. The mixed type of failure was the most common in all groups.

Conclusions

Self-etching (G4) and self-adhesive resin (G5) cements, showed similar BS results of immediate bonding in the cementation of GFP compared to conventional resin cements (G1, G2, G3). Key words:Dental Cements, Dentin-Bonding Agents, Post and Core Technique, Dental Bonding.

Bond strength and failure mode of glass fiber posts with different surface treatments prior to silanization: An in vitro comparative study

Aim

The use of chemical agents in the surface treatment of glass fiber posts can improve their bond strength to the root canal. The aim of this study was to assess the bond strength and failure mode of glass fiber posts that received different surface treatments prior to silanization.

Materials and Methods

In this cross-sectional and in vitro experimental study, 50 human lower premolar roots were randomly divided into five groups and subsequently prepared to receive the cementation of a fiberglass post prior to silanization. They were distributed as group 1 (with 24% hydrogen peroxide), group 2 (with 37% phosphoric acid), group 3 (with 1.23% acidulated phosphate fluoride for 2 minutes), group 4 (with 1.23% acidulated phosphate fluoride for 6 minutes), and group 5 (without pretreatment). After cementation, the roots were sectioned into two discs for each cervical, middle, and apical region. Bond strength was assessed using the push out technique. Adhesive, mixed, and cohesive failure modes were also assessed. For data analysis, ANOVA and Tukey's post hoc tests were used, as well as Pearson's chi-square test. A significance of P < 0.05 was considered in all statistical analyses.

Results

When comparing the bond strength of root regions, significant differences were obtained in groups pretreated with phosphoric acid (P = 0.018) and acidulated phosphate fluoride for 2 and 6 minutes (P = 0.001 and P = 0.000, respectively). Furthermore, significant differences were obtained between posts treated only with silane and those that received phosphoric acid pretreatment (P = 0.006) and acidulated phosphate fluoride for 6 minutes (P = 0.001). Significant association of mixed failure mode was observed with hydrogen peroxide (P = 0.014) and phosphoric acid (P = 0.006) pretreatments. Cohesive failure was significantly associated with acidulated phosphate fluoride pretreatment for 2 minutes (P = 0.032) and with posts that did not receive treatment prior to silanization (P = 0.000).

Conclusion

Posts treated only with silane and pretreated with hydrogen peroxide and acidulated phosphate fluoride for 2 minutes presented significantly higher bond strength with respect to those pretreated with phosphoric acid and acidulated phosphate fluoride for 6 minutes. However, acidulated phosphate fluoride for 2 minutes and silane were associated with a better bonding type.

Temporary cement residues affect the bond strength and dentin penetration of self-adhesive resin cement in fiberglass post cementation

This study evaluated the persistence of eugenol-containing (PR, Provy) or eugenol-free (RT, Relyx Temp, and TB, Temp Bond) temporary cement residues and its effects on push-out bond strength and dentinal penetration of the self-adhesive resin cement (Relyx U200). Eighty human roots were endodontically treated and post space prepared. Fourty specimens were distributed in four groups (n = 10): Control (CO), without any clinical procedure, PR, RT, and TB, where a metallic post was cemented with one of the temporary cements. After metallic post removal, hemi sections post space were submitted to SEM analysis. Another specimens were distributed in similar groups, but fiberglass post was cemented using Relyx U200 cement and submitted to push-out bond strength and dentinal penetration cement analysis, in post space thirds. SEM analysis were evaluated by Kruskal-Wallis and Dunn tests, while bond strength and dentinal penetration were evaluated by ANOVA One-Way and Tukey test (p < .05). Only in apical thirds, PR, RT, and TB showed higher persistence of residues than CO. In bond strength, PR, RT, and TB showed lower values than CO, in all post space thirds (p < .05). But to dentinal penetration, PR, RT, and TB presented lower values than CO only in apical thirds (p < .05). There is the greatest persistence of temporary cement residues only in apical post space third, providing less dentinal penetration of the self-adhesive resinous cement. However, the previous use of temporary cements has negative effects on the bond strength cementation system, regardless of the third evaluated.

The effect of two endodontic sealers and interval before post-preparation and cementation on the bond strength of fiber posts

OBJECTIVES

To evaluate the effect of different endodontic sealers (epoxy resin-based and bioceramic-based) and the time of post-cementation on the bond strength of a fiber post cemented with resin cement.

METHODS

Forty human premolars were instrumented and divided into 4 groups. According to the type of sealer and the time of post-cementation: AH-IM (AH Plus, post-cemented immediately after root canal treatment), SP-IM (iRoot SP, post-cemented immediately after root canal treatment), AH-OW (AH Plus, post-cementation after one week), and SP-OW (iRoot SP, post-cementation after one week). In each group, the samples were submitted to push-out test, and failure mode was assessed. Levene's test, one-way ANOVA, and Kruskal-Wallis analysis were applied for statistical analysis (α = 5%).

RESULTS

The highest mean push-out bond strength was obtained from the SP-IM group in the apical part (10.45 ± 5.15MPa), while the lowest was observed in samples from the AH-OW group in the middle part (2.63 ± 1.54 MPa). One-way ANOVA showed that within the same root region, the time of post-cementation had a negative influence on the bonding strength in the SP groups in the middle and apical portion (P<0.05), however, when comparing the effect of type of sealers on bonding strength between the OW groups or IM groups within the same root region, no significant difference was observed regardless of the post cementation time (P>0.05).

CONCLUSIONS

The bond strength of the fiber post was higher when the post was cemented immediately after root canal treatment when the bioceramic sealer was applied.

CLINICAL RELEVANCE

The correct choice of an endodontic sealer and the proper time of post-cementation may help to obtain the best quality of post-and-core restoration.

Postspace pretreatment with 17% ethylenediamine tetraacetic acid, 7% maleic acid, and 1% phytic acid on bond strength of fiber posts luted with a self-adhesive resin cement

Context:

Pretreatment of radicular dentin with chelating agents improves the bond strength of fiber-posts luted with a self-adhesive resin cement.

Aims:

The aim of this study was to assess the effects of the three chelating agents as final rinse of the postspace on bond strength of fiber posts luted with a self-adhesive resin cement.

Settings and Design:

This is an in vitro laboratory study.

Materials and Methods:

Forty-five mandibular premolars were prepared using MTwo rotary system and irrigation was done with 2.5% sodium hypochlorite. Three groups of teeth samples were considered for postspace preparation and irrigated with different solutions: Group 1: 17% ethylenediamine tetraacetic acid (EDTA); Group 2: 7% Maleic acid; Group 3: 1% Phytic acid. This was followed by the luting the posts with RelyX U200. After a week, from each sample, 2 mm thick slices were obtained from each third of the root and subjected to push-out bond strength testing.

Statistical Analysis Used:

One-way analysis of variance and Bonferroni's Post hoc analysis was used for assessing the results. The statistical significance level was set at P < 0.05.

Results:

Bond strength values were improved with maleic acid and phytic acid pretreatment with slight or no significant difference between these groups. A final rinse of postspace with EDTA significantly reduced the bond strength.

Conclusions:

Maleic acid (7%) pretreatment of postspace improved the adhesion of fiber posts luted with a self-adhesive resin cement.

Effect of irrigation protocol during post space preparation on the dentin adhesive interface: An in vitro study

STATEMENT OF PROBLEM

The post space must be prepared with techniques that do not interfere with the bond strength. These techniques are related to the availability of opened dentinal tubules and incidence of residue among the dentin, the adhesive, and the cement. Nevertheless, the effect of different irrigants during endodontic instrumentation is unclear.

PURPOSE

The purpose of this in vitro study was to assess the incidence of residue, the number of opened dentinal tubules, and the bond strength of the cementation system to root dentin of post space after 3 different irrigation protocols.

MATERIAL AND METHODS

The roots of bovine incisors were obturated, prepared to receive a fiber post, and divided into 3 groups as per the irrigation protocol: without irrigation, with alternating irrigation, and with continuous irrigation. Thirty roots (n=10) were evaluated by using scanning electron microscopy to assess the incidence of residue (×100 magnification) and the number of opened dentinal tubules (×2000 magnification). The fiber posts were cemented, and the remaining specimens (n=10) were subjected to pushout testing and failure mode evaluation.

RESULTS

All protocols presented a similar incidence of residue, regardless of the post space third (P>.05). The irrigation protocol without irrigation had the lowest number of opened dentinal tubules in the cervical and middle thirds (P<.05). The number of opened dentinal tubules was similar in all protocols in the apical third of the post space (P>.05). The irrigation protocol without irrigation had the lowest bond strength values in the cervical and middle thirds (P<.05). The irrigation protocol with continuous irrigation had the highest bond strength values in the apical third (P<.05).

CONCLUSIONS

Post space preparation without irrigation negatively affected the bond strength of the resin cementation system to root dentin.

Effect of the Photo-initiator System Contained in Universal Adhesives on Radicular Dentin Bonding

CLINICAL RELEVANCE

The photo-initiator system based on an advanced polymerization system may be an alternative that can be used to overcome the disadvantages of radicular dentin, especially for the apical third.

SUMMARY

Objectives: The purpose of this study was to evaluate the effects of universal adhesives with different photo-initiator systems applied in etch-and-rinse (ER) and self-etch (SE) modes on dentin interaction (push-out bond strength [PBS], nanoleakage [NL], and degree of conversion [DC] within the hybrid layer) in the different root thirds after fiber post cementation.Methods and Materials: Roots of endodontically prepared human premolars were randomly divided into six groups according to one of three adhesive systems (Scotchbond Universal [SBU], Ambar Universal [AMB], and Ambar Universal APS [AMB-APS]) and two adhesive strategies (ER and SE) for each system. Posts were cemented, and PBS was tested at 0.5 mm/min. The NL was evaluated by scanning electron microscopy. DC was measured using micro-Raman spectroscopy. The data were analyzed by three-way analysis of variance and Tukey tests (α=0.05).Results: AMB-APS showed similar performance in all root thirds (p>0.05) and higher values of DC, especially in the apical third (p<0.0001). AMB and SBU showed the lowest values in the apical third (p<0.0001).Conclusions: The APS photo-initiator system contained in universal adhesives is a feasible alternative for improving radicular bonding procedure.

Influence of the depth of intraradicular dentin on the pushout bond strength of resin materials

AIM

The aim of the present study was to evaluate the pushout bond strength between glass-fiber posts to different regions of intraradicular dentin with different materials for adhesive cementation.

METHODS

After endodontic filling, 40 teeth were divided into five groups according to adhesive cementation: Adper Single Bond 2 + RelyX ARC, Excite DSC + RelyX ARC (EXC), Adper SE Plus + RelyX ARC (SEP), RelyX Unicem, and Set. After the bonding process, roots were sectioned obtaining slices to be analyzed from each third. The bond strength was measured using the pushout test in a universal testing machine (Emic DL 3000) at a cross-head speed of .5 mm/minutes in different areas of the post space (cervical, middle, and apical). Data were subjected to analysis of variance and Fisher's test (α = .05).

RESULTS

The highest values for the pushout bond strength were found for the SEP group in all experimental conditions, without a significant difference for the EXC group in the middle and apical regions. There was a decrease in pushout bond strength in the cervical-apical direction for all groups, except the EXC group, which did not show a difference among the different regions.

CONCLUSIONS

The different interactions of the resin materials and the intraradicular depth influenced the bond strength of adhesives materials to dentin substrate.

Effect of a filled adhesive as the desensitizer on bond strength of "Self-Adhesive Cements To" differently severity of fluorosed dentin

The objectives were to evaluate the efficacy of a filled adhesive named Prime & Bond NT (P&B NT) as the dentin desensitizer in occluding fluorosis dentinal tubules and compare the shear bond strength (SBS) of RelyX U200 self-adhesive resin cement (RXU) and RelyX Luting self-adhesive resin-modified glass ionomer cement (RMGIC) before and after P&B NT pretreatment. 176 non-carious fluorosis were classified into four subgroups by the Thylstrup and Fejerskov index (TFI): normal group (TFI = 0), mild group (TFI = 1-3), moderate group (TFI = 4-5), severe group (TFI = 6-9). 160 composite cylinders (4 × 5 mm) were fabricated, then every severity of fluorosed dentin was subjected to four treatments: P&B NT + RXU (n = 40), RXU (n = 40), P&B NT + RMGIC (n = 40), RMGIC (n = 40). The specimens were immersed in water at 37°C for 24 hr first and half of them underwent 5,000 thermocycling before shear bond strength test. A factorial design (factorial 4 × 2 × 2 × 2) was developed to make statistical analysis. Scanning electron microscope (SEM) analysis (n = 16) in cross section and longitudinal section view characterized the occlusion situation of dentinal tubules. P&B NT might occlude dentinal tubules as the dentin desensitizer for normal teeth and mild-moderate fluorosis. P&B NT significantly increased the SBS of RXU (p < .05) but had no statistical significance on the SBS of RMGIC (p > .05). RXU could benefit from P&B NT desensitization to achieve a better quality of adhesion.