Acid Etching and Surface Coating of Glass-Fiber Posts: Bond Strength and Interface Analysis

Effects of different surface treatments on surface topography and bond strength in the repair of fiber-reinforced dentin composite

OBJECTIVE

This study aimed to evaluate the effects of different surface treatments on the repair bond strength between a fiber-reinforced dentin composite and a posterior composite.

METHODS

Forty fiber-reinforced dentin composite resin blocks (4 mm × 4 mm × 4 mm) were separated into eight groups (n = 5) according to the surface preparation methods: (G1) negative control group, (G2) adhesive application, (G3) 50% dimethylsulfoxide (DMSO) application, (G4) 50% DMSO + adhesive application, (G5) 37% phosphoric acid etch + adhesive application, (G6) air abrasion + adhesive application, (G7) 37% phosphoric acid etch + 50% DMSO application + adhesive application, and (G8) air abrasion +50% DMSO application + adhesive application group. The composite surfaces were repaired in two layers with a posterior composite. Composite sticks were subjected to a micro tensile bond strength (μTBS) test. Fractured surfaces were evaluated using a stereomicroscope (×25). Short fiber-reinforced composite samples' surfaces were investigated by scanning electron microscope (SEM). Shapiro Wilk, one-way ANOVA, and Tukey HSD tests were used for statistical evaluation.

RESULTS

The highest average (μTBS) values were observed in G8, whereas the lowest mean μTBS values were evident in the G1 group. Statistically significant μTBS values were found in all adhesive-applied groups when compared with the negative control group. Notably, the application of 50% DMSO without adhesive did not lead to a statistically significant increase in μTBS values. SEM images demonstrated that acid etching partially eliminated residues on the composite surface, while air abrasion had a detrimental effect on the integrity of fiber structures.

CONCLUSION

In the repair of fiber-reinforced dentin composite with a posterior composite, adhesive application is an effective approach. The treatment of 50% DMSO without adhesive did not confer a statistically significant advantage, and the supplemental use of acid etch or air abrasion did not show an additional benefit compared to adhesive-only repairs.

CLINICAL SIGNIFICANCE

Adhesive application emerges as a potent and effective strategy for the repair of bur-roughened fiber-reinforced dentin composites. With its limitations, the study highlights the efficacy of adhesive-only repairs without the necessity for additional surface treatments.

Effect of reapplication on pull-out bond strength of fibre post to root dentin: An in vitro study

Purpose

Post removal may be necessary for many reasons and is inevitable after the re-application of a dental post. The present study investigated the bond strength between root dentin and a re-applied fibre-reinforced composite (FRC) post by a pull-out test.

Materials and methods

After root canal treatments of 30 extracted human maxillary canine teeth, post spaces were prepared (10 mm), and FRC posts (Hi-Rem Post; Overfibres, İmola, Italy) were luted with self-adhesive resin cement. The samples were than randomly divided into test and control groups (n = 15 in each). The FRC posts were removed in the test group, and new posts were cemented. The pull-out test (1 mm/minute speed) was used to measure the bond strength. Failure types were determined using a stereomicroscope. Mann-Whitney U, chi-square and Fisher-Freeman-Halton exact tests were used for statistical analysis.

Results

The bond strength values of the test (119.5 ± 36.86 N) and control (115.55 ± 55.44 N) groups did not differ significantly (p >.05). In terms of the percentage of failure types, there was a significant difference only in the test group between the mixed failure type and the other failure types (p <.05).

Conclusions

The re-application of FRC post did not seem to affect the bond strength. The distribution of failure types was similar between the control and test groups.

Push-out bond strength and SEM fractographical analysis of hollow fibre posts used with self-adhesive resin cement: a pilot study

Detachment is the major cause of failure of endodontic fibre posts. Hollow posts have been recently introduced to overcome such issue. The primary aim of this pilot study was to compare the push-out bond strength of hollow posts and traditional solid posts. Eight round-shaped single-canal premolars extracted for periodontal reason were selected as sample and equally randomized into two groups: (i) traditional solid fibre posts-TECH21xop and ii) hollow fibre posts-TECHOLE. A dual-curing self-adhesive cement (new TECHCEM) was used for posts placement. Six horizontal sections-two from each portion of the root (coronal, middle and apical)-were obtained from each sample root, yielding a total of 24 sections for each group. Push-out test was performed on the sections and bond strength values were compared between groups and within each group. Scanning electron microscope (SEM) fractographical analysis was conducted on each section. Additional SEM and EDX analyses were performed on new samples of both posts, to assess fibres density and distribution, and the chemical composition of the fibres and the matrix. Hollow posts showed a significantly higher push-out bond strength (6.36 ± 1.22 MPa) than solid posts (3.64 ± 1.62 MPa). Among the three root portions of the same group, there was no significant difference in bond strength. In both groups, the most frequent type of fracture was a mixed adhesive failure with the cement covering 0 to 50% of the post perimeter. Hollow post fibres appear more similar in size and have a more homogeneous distribution, compared to solid posts. The two post types also have different chemical compositions.

Effect of Different Silane Coupling Agents on the Bond Strength between Hydrogen Peroxide-Etched Epoxy-Based- Fiber-Reinforced Post and Composite Resin Core

The aim of the study was to evaluate the effect of various silane coupling agents on the micro-push-out bond strength between a hydrogen peroxide-etched epoxy-based fiber-reinforced post and composite resin core. Seventy-five cross-linked epoxy-based fiber-reinforced posts were etched with 24% hydrogen peroxide for 10 min. Then they were divided into five groups according to various silane coupling agents and bonded to a composite core. A Universal Testing Machine was utilized to evaluate the push-out bond strength. In addition, all groups' modes of failure were assessed. The push-out bond strength data in MPa were analyzed using ANOVA and a Tukey HSD post hoc test to reveal any difference between the groups. Results revealed that the application of a two-bottle silane coupling agent exhibited the highest bond strength, while the application of a one-bottle silane coupling agent demonstrated the lowest bond strength for a hydrogen peroxide-etched fiber post bonded to a composite core material, which was statistically significant (p < 0.05). The strongest association with the highest bond strength was found with the two-bottle silane coupling agent when compared to the one-bottle. The study highlighted that the application of a silane-coupling agent may affect the bond strength between composite and epoxy-based fiber-reinforced posts.

Push-out Bond Strength of Two Fiber Posts in Composite Resin Using Different Types of Silanization

OBJECTIVES

The aim of this study was to evaluate the effect of different surface treatments and thermocycling (TC) on the push-out bond strength of two brands of glass fiber posts (GFPs) to composite resin.

METHODS

White Post DC (WP) (FGM Dental Group International, Joinville, Santa Catarina, BR) and Exacto (EC) (Angelus, Clinical Research Dental, Londrina, PR, Brazil). GFPs were cleaned with 70% alcohol and divided into five groups, according to the surface treatment (n=15): control (C), without treatment; prehydrolyzed silane (S-pre) (Prosil, FGM Dental Group International); 37% phosphoric acid + prehydrolyzed silane AcS-pre); Scotchbond Universal Adhesive System (AdU), 3M Oral Care; two-bottle silane (S2B) (Dentsply Sirona Inc). The composite resin was inserted around the posts by using a split matrix. The samples were cut into 1-mm slices. Half of the samples were subjected to the push-out test immediately, and the other half underwent TC before the test. After failure analysis, the data were submitted to three-way analysis of variance (ANOVA) (α=0.05).

RESULTS

EC achieved higher bond strength than WP, regardless of TC (p<0.05). Regarding WP, surface treatments (p<0.001) and TC (p<0.001) influenced bonding strength. As for EC without TC, the highest bond strength (p<0.05) was found for C, then AcSpre, S-pre, AdU, and S2B. Application of TC resulted in a statistically higher bond strength values for the EC AcS-pre group (p<0.05), followed by S2B, S-pre, C, and AdU. The WP failures were predominantly cohesive, similar to the EC AdU and EC S2B groups. The other EC groups showed mostly mixed failures.

CONCLUSIONS

Surface treatment and TC affected the bond strength to composite resin, depending on which post was used. It is important for dentists to understand the effects of different types of silanization on their chosen post.

Photodynamic therapy and other pretreatment methods on epoxy-based glass fiber post on the push-out bond strength to radicular dentin

AIM

To assess the push-out bond strength (PBS) of glass fiber post (GFP) conditioned using different surface treatment regimens bonded to radicular dentin MATERIAL AND METHODS: Sixty central incisors and canine were collected and disinfected. Decoronation following working length was determined using K-file. Rotary file system was used for cleaning and shaping. Canals of all samples were dried with paper points and obturated with gutta percha. Canal space was prepared with peso reamers. Now samples were randomly allocated into six groups based on pretreatment of GFP. Post in group 1 treated with 9% HFA+ Silane, post in group 2 surface treated with silane only, Post in group 3 surface treated with airborne particle (50 µm), group 4 post conditioned with photodynamic therapy (PDT), group 5 post pretreatment was performed with MBP and in group 6 GFP was not treated. Conditioned and non-conditioned posts were positioned in canal space and cemented. Tooth were sectioned coronally, middle and apically. Sections were positioned in universal testing machine (UTM) and debonded surfaces were evaluated for failure modes. The means and standard deviations of PBS were examined using one-way analysis of variance (ANOVA).

RESULTS

Coronal third of group 3 in which posts were sandblasted using airborne Al₂O₃ particle presented the highest PBS (11.21±0.64 MPa). Whereas, an apical section of group 4 in which posts were treated with PDT exhibited the lowest bond integrity.

CONCLUSION

Sandblasting using airborne particles (50 µm) and hydrogen peroxide (H₃PO₄) conditioned with GFP exhibited significantly higher bond strength as compared to the control. However, PDT decreases the PBS of fiber post with the root dentin.

Surface treatments of a glass-fiber reinforced composite: Effect on the adhesion to a composite resin

PURPOSE

To compare the effect of different surface treatments (pre-treatments and bonding agents) on the bond strength between glass-fiber post and composite resin, and the topographic alterations of the treated post surface.

METHODS

Thirty-six glass-fiber blocks (12mm×10mm×8mm) were specifically manufactured for this study and randomly assigned into 12 groups considering two factors: 'pre-treatments' (-cleaning with 70% alcohol; air-abrasion with silica-coated aluminum oxide particles; 35% hydrogen peroxide) and type of 'bonding agent' (no bonding agent; application of Monobond Plus; RelyX Ceramic Primer; Single Bond Universal). After that, 6 cylindrical templates (1mm high×1mm Ø) were fixed on each block, filled with composite resin (n=18) and light-cured. Specimens were stored under 37°C for 24h and microshear tests (wire loop Ø=0.2mm) were performed. Topographic, roughness and failure analyses were also performed.

RESULTS

Different surface pre-treatments led to different topographic and roughness alterations; a higher surface alteration was noted after silica particles air-abrasion, while a slight surface alteration in the hydrogen peroxide group and a smooth pattern were observed in the cleaning group. The factors 'pre-treatments' (p<0.05), 'bonding agent' (p<0.05) and their interaction (p<0.05) influenced the bond strength. Silica coating, apart from bonding agent application, or Single Bond Universal application without pre-treatment promoted the highest bond values. The main failure type was adhesive at the resin-post interface.

CONCLUSIONS

In terms of pre-treatments, silica coating promotes the best bonding performance, but pre-treatments can be dispensable when applying Single Bond Universal.

Pino de fibra de vidro anatômico: relato de caso

Introdução: Pinos pré-fabricados de fibra de vidro possuem boas propriedades mecânicas e estéticas. Porém, estes podem não se adaptar bem em canais amplos ou excessivamente cônicos, prejudicando sua retenção ao canal radicular. Uma alternativa para esta desvantagem é a utilização da técnica de pino anatômico. Objetivo: O objetivo do relato de caso foi apresentar a técnica de confecção de um pino fibra de vidro anatômico em dente anterior, com reduzido remanescente coronário e ampla embocadura do canal radicular. Relato de Caso: Paciente masculino, 49 anos, procurou atendimento odontológico com queixa da aparência estética de seus dentes anteriores superiores. Após remoção de uma coroa metalocerâmica e um pino-núcleo metálico fundido do elemento 12, foram confeccionados um pino de fibra de vidro anatômico, núcleo de preenchimento e coroa provisória. Foram realizadas as facetas em resina composta nos elementos 13, 11, 21, 22 e 23. Uma coroa de cerâmica reforçada por dissilicato de lítio (IPS e.max CAD, Ivoclar Vivadent) foi cimentada no elemento 12. Conclusões: Através da técnica pino de fibra de vidro anatômico, é possível reabilitar dentes anteriores tratados endodonticamente sem a utilização de pinos metálicos, apresentando bons resultados estéticos. Entretanto, uma condição oclusal dentro dos princípios de uma oclusão mutuamente protegida deve ser almejada para garantir longevidade da restauração.