Effects of adhesive systems and luting agents on bonding of fiber posts to root canal dentin

Push-Out Bond Strength of Resin-Modified Glass Ionomer Cement and Flowable Composite Luting Systems on Glass Fiber Post of Root Canal

Background: Posts that have been properly fitted can withstand torsion forces and so provide better retention. The push-out bonding strength of glass fiber posts to the root canal was evaluated using resin-modified glass ionomer cement (RMGIC) and flowable composite (FC). Method: Forty single-rooted maxillary central incisors were used in the study. The samples were randomly divided into two groups of 20 teeth each. The crown-down procedure was used to clean and shape the pulp area. A Tenax fiber trans Coltene whaletene post was used by both groups. The first group utilized FC (Filtek Z 350 3M ESPE) to coat the post, whereas the second group used RMGIC (Rely X 3M ESPE). The specimens were cross-sectioned after 24 h. Specimens were cross-sectioned four millimeters thick into coronal and middle parts using a sectioning machine, yielding 40 specimens per group. The strength of the bond between the luting cement and the posts was measured using push-out bond strength testing. We loaded the components at a cross speed of 0.5 mm/min on a universal testing machine until the bond failed. Results: The FC group had a 4.80 N push-out bond strength, whereas the RMGIC group had a 7.11 N push-out bond strength. Conclusion: FC’s mean push-out bond strength score is lower than RMGIC’s.

Comparison between two post-dentin bond strength measurement methods

The push-out (PO) test and the diametral compression (DC) test were performed to compare the merits of two post-dentin bond strength measurement methods. Compared with the push-out test, the disk in DC provided post-dentin bond strength measurements that were more precise. The load-displacement curves from the DC test were much smoother and more linear up to the point of fracture when compared to those from the PO test. Compared to the PO test, DC is easier to perform for determining the bond strength between posts and dentin. No specimen alignment is needed in the DC test, and it produces a smaller standard deviation in the measured bond strength. The main disadvantage of the DC test, however, is that finite element analysis (FEA) is required to calculate the bond strength. The shear bond strength given by the PO test based on the simple formula is not valid, though, and the peak failure load is dependent on friction at the post-dentin interface.

Push-out bond strength of different translucent fiber posts cemented with self-adhesive resin cement

PURPOSE

Evaluate the bond strength of different translucent fiber posts in the cervical, middle, and apical root thirds cemented with self-adhesive resin cement.

MATERIALS AND METHODS

Sixty single-rooted teeth were randomly divided into five groups according to the fiber post used: Reforpost (opaque [control]), exacto, white post, radix, and Macro-Lock Illusion X-RO. The roots were subjected to chemomechanical preparation and cemented with self-adhesive resin cement. The teeth were sectioned into slices of the different root thirds and tested for bond strength (push-out). Two-way analysis of variance and Bonferroni test were used to verify statistical differences between groups (P < 0.05).

RESULTS

No significant difference between the root thirds was detected (P > 0.05). However, the performance of the posts demonstrated a significant difference (P < 0.05). RDX had a lower performance in the apical third (P < 0.05). The other fiber posts had the same performance irrespective of the root third evaluated. The predominant failure pattern was adhesive between resin cement and root dentin.

CONCLUSION

In general, the different translucent fiber posts showed the same performance. Yet, translucent fiber posts did not show superior bond strength compared with the opaque fiber post in any of the root thirds evaluated.

Microtensile bond strength between a UDMA fiber post and different resin cements: Effect of pre-surface treatment

During a fiber post cementation, bonding failure often occurs at the junction between the fiber-post and resin-cement. Because this failure requires better characterization, we evaluated if different post surface treatment can affect the bond strength of urethane dimethacrylate (UDMA) fiber-posts with resin-cements. Three groups were created: G1: no treatment/silane; G2: ethyl alcohol (96° GL)/silane; G3: 24% H₂O₂/silane and further divided into four subgroups: I-Unicem/3MESPE; II-BisCem/Bisco; III-Panavia SA/Kuraray and IV-DuoLink/Bisco. Blocks of cured resin cements and posts placed in the center were serially cut into bar-shaped specimens and loaded into a micro tensile testing machine. ANOVA indicated no significant differences among post surface treatments (p>0.05), however, significant within the resin cements (p<0.05) and the interaction of both (p<0.05). The G3/IV showed the highest bond strength values. SEM showed that surface treatments on UDMA fiber posts presented no benefits in terms of surface roughness, thus, should not be performed.

Effects of different surface pre-treatments on the bond strength of adhesive resin cement to quartz fiber post

OBJECTIVE

The purpose of this study was to evaluate the effect of mechanical and chemical surface treatment methods on the bond strength of resin cement to fiber post.

MATERIALS AND METHODS

The roots of 36 maxillary central incisor teeth were mounted in auto polymerized acrylic resin blocks (10 × 15 mm) and the root canals were enlarged with the drills of post system (2.1 mm width, 12 mm length). Thirty-six fiber posts were randomly assigned to one of the following surface conditioning methods: silane coupling agent, methylene chloride etching, 24% hydrogen peroxide etching, air abrasion with 50 µm Al(2)O(3), 1-3 µm synthetic diamond particles and silica coating with 30 µm SiO(x). Fiber posts were cemented to the root canals with adhesive resin cement (Panavia F 2.0). Three slices of 1.5 mm thick were obtained from each root. Push-out tests were performed with a universal testing machine. The data were analyzed with one-way analysis of variance (ANOVA) and Tukey HSD tests (α = 0.05). The effect of the surface treatments were examined under a scanning electron microscope (SEM) and surface roughness were evaluated with a profilometer.

RESULTS

Surface pre-treatment methods affected the bond strength (p < 0.05). The highest bond strengths were obtained by air abrasion with synthetic diamond particles, the lowest bond strength were obtained by etching with methylene chloride (p < 0.05).

CONCLUSION

Mechanical surface pre-treatment methods showed higher bond strength values than chemical methods. Synthetic diamond particles may be an alternative method to increase resin cement bonding on the quartz fiber post surfaces.

Fiber post placement with core build-up materials or resin cements-an evaluation of different adhesive approaches

OBJECTIVE

To compare push-out bond strength of fiber-posts luted with different adhesive approaches to root canal dentin.

MATERIALS AND METHODS

Forty maxillary first incisors were decoronated and endodontically treated. Specimens were randomly distributed into five groups (n = 8) and fiber-posts (DentinPost coated, Komet) were inserted using five different luting materials: etch-and-rinse adhesive systems and corresponding core-and-post material in groups 1 (DentinBond/DentinBuild, Komet) and 2 (XP Bond + SCA/Core-X flow, Densply), self-adhesive resin cements in groups 3 (RelyX Unicem, 3M Espe) and 4 (SmartCem 2, Dentsply) and a self-etch adhesive/resin cement in group 5 (ED-Primer II/Panavia F 2.0, Kuraray). The roots were sectioned into eight 1 mm thick serial slices and within 48 h push-out bond strength was investigated. Statistical analyses were performed using non-parametrical Kruskal-Wallis H-test and Mann-Whitney U-test for differences between experimental groups at p < 0.05. The failure modes were analyzed using Chi square test.

RESULTS

The bond strength [MPa] (mean/min-max) for groups 3 (12.35/3.60-32.44), 4 (13.52/4.48-30.69) and 2 (11.15/5.23-35.58) were significantly higher (p < 0.001) compared to groups 1 (6.66/2.34-24.89) and 5 (7.41/0.28-34.18). Adhesive failure between dentin and luting agent was the most frequent failure mode.

CONCLUSIONS

Bond strength of fiber-posts adhesively luted to root canal dentin was significantly higher when self-adhesive resin cements were used. One (group 2) of the tested core-and-post materials/etch-and-rinse adhesive achieved comparable bond strength values.

Translucent fiber post cementation using light- and dual-curing adhesive techniques and a self-adhesive material: push-out test

OBJECTIVES

To compare, by means of the push-out test, the interfacial strength of two dual resin cements and one light-curing cement when used in translucent fiber post cementation.

METHODS

Thirty-nine, endodontically treated, single canal, extracted human bicuspids were selected. Translucent fiber posts (RelyX Fiber Post) were luted into the root canal using three resinous luting systems (n=13). Dual-curing technique (DC): the specimens were treated with Excite DSC and RelyX ARC, which were light-cured simultaneously through the post for 60s. Self-adhesive dual-curing technique (SADC): the specimens were treated with RelyX Unicem, which was light-cured through the post for 60s. Light-curing technique (LC): the specimens were treated with Excite DSC and Tetric Flow, which were simultaneously light-cured through the post for 60s. The specimens were transversally sectioned into six slices in order to perform the push-out test. Data were analyzed by two-way ANOVA followed by the Tukey-Kramer test for post-hoc comparisons at alpha=0.05.

RESULTS

At every region, results did not show any statistical difference between the DC and LC techniques. With the LC technique bond strength values were lower at the apical region than those recorded at the coronal and middle regions. At the coronal and middle regions, bond strength values for the SADC technique were lower than those resulting when using the other two techniques. At the apical region, there was not significant difference in bond strength between the luting techniques tested.

CONCLUSIONS

The interfacial strength between light-curing cement and root canal is equivalent to the interfacial strength between dual-curing cement and root canal.

Retention of fiber posts cemented at different time intervals in canals obturated using an epoxy resin sealer

OBJECTIVES

To evaluate the effect of immediate versus delayed post space preparation and cementation on the retention of different types of fiber posts in canals obturated with an epoxy resin sealer.

METHODS

Sixty-eight single-rooted human teeth were decoronated and the root canals were shaped with rotary instruments and obturated with gutta-percha and an epoxy resin sealer. The teeth were divided into four experimental groups according to the different times of post space preparation and cementation: immediate (group 1), 24h (group 2) and 1 week (group 3) after root canal filling. Control group (group 4) with no root canal obturation was included. Two teeth were randomly selected from each group for SEM examination. Each group was further divided into three subgroups of five teeth each (n=5), according to the type of post and the materials used for luting the posts. A push-out test was performed and differences among experimental groups were analyzed with two-way ANOVA and Tukey test (alpha=0.05).

RESULTS

Interfacial strength values achieved in group 1, where an immediate cementation was performed, were significantly lower (p<0.05) than those in group 2 and group 3 in which post cementation was performed 24h or 1 week after the root canal filling. Post type affected post retention, FRC Postec and DT Light Post posts achieved higher interfacial strengths than ENA Post (p<0.05). SEM examination revealed a more conspicuous presence of sealer remnants on the walls of immediately prepared post spaces.

CONCLUSIONS

Delayed cementation of fiber post resulted in higher retentive strengths irrespective of the post type.

Laboratory assessment of the retentive potential of adhesive posts: a review

OBJECTIVES

This review aimed at summarizing the laboratory evidence collected on the retentive ability of adhesive posts since their introduction in dentistry.

DATA

Data were searched in articles published or in press in peer-review journals listed in MEDLINE.

SOURCES

Papers were retrieved through PubMed.

STUDY SELECTION

To collect the evidence of interest, the following search terms were used: bond* AND fiber post AND in vitro; lut* AND fiber post AND in vitro; push-out AND fiber post; pull-out AND fiber post; microtensile AND fiber post. "Related Links" were also considered and articles cited in the initially retrieved papers were included if relevant. No time limit was given to the query.

CONCLUSIONS

Seventy relevant papers were reviewed. The retentive ability of adhesive posts has been tested with the microtensile technique, post-pull-out and push-out tests. If small-sized specimens are obtained, such as in microtensile and thin-slice push-out, stress uniformity is favoured, local differences in bonding conditions can be discerned, and the number of teeth needed for the test can be reduced. Although adhesion to intraradicular dentin is more challenging to achieve than bonding to crown tissues, the post-retention achieved with current luting systems and techniques is adequate to ensure the clinical success of adhesive post-retained restorations. To enhance the bond at the post-core and post-cement interfaces, several chemical pre-treatments of the post-surface have been tested with positive results. Self-adhesive resin cements, recently proposed to simplify the post-luting procedure, should be investigated further with regard to durability.

Comparison of regional bond strength in root thirds among fiber-reinforced posts luted with different cements

AIM

To compare regional bond strength in different thirds of the root canal, among glass fiber-reinforced (FRC) endodontic posts luted with different cements, using the push-out test.

MATERIAL AND METHODS

Sixty extracted human anterior teeth were endodontically treated with gutta-percha and AH Plus sealer. The crown portion was removed, and a dowel space was prepared. Prepared teeth were randomly assigned to one of six groups (n = 10) for luting glass FRC Postec posts, with one of the six cement systems (Ketac Cem Aplicap, Relyx Unicem Aplicap, Variolink II/Excite DCS, Panavia F/ED Primer, C&B cement/All-Bond 2, and Multilink/Multilink Primer A/B), using an alignment technique. Specimens were embedded in resin, and each root was sectioned into six 1-mm thick serial slices. A push-out test was performed to measure regional bond strengths and to identify the type of failure.

RESULTS

The highest bond strength values were found in the cervical third and the lowest in the apical third. Highest values were obtained using Variolink II, Panavia F, and Multilink resin cements followed by C&B resin cement and Relyx Unicem ionomer resin cement; Ketac-cem ionomer cement showed the lowest value.

CONCLUSION

Highest bond strength values were obtained in the cervical third and with resin cements.

The Effect of Immediate Versus Delayed Cementation on the Retention of Different Types of Fiber Post in Canals Obturated Using a Eugenol Sealer

Post can be placed immediately after the completion of the endodontic procedure or at a later stage after setting of the sealer. In this in vitro study, post space preparation and post cementation were performed immediately (group 1), 24 h (group 2), and 7 days (group 3) after root filling. A control group with no root canal obturation was included (group 4). Each group was further divided into three subgroups, according to the post type and to the materials used for luting the post. A push-out test was performed to evaluate post-root canal dentin interfacial strength. Differences among experimental groups were analyzed with two-way ANOVA and the Tukey test. Significant differences (p < 0.05) in interfacial strengths were observed for the factors post cementation interval and post type. Clinicians should be careful in performing immediate cementation of fiber posts, as delayed cementation shows higher post-dentin interfacial strengths irrespective of the post type.