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ORIGINAL ARTICLE
Year : 2018  |  Volume : 21  |  Issue : 3  |  Page : 350-355

Effects of Postsurface Treatments Including Femtosecond Laser and Aluminum-oxide Airborne-particle Abrasion on the Bond Strength of the Fiber Posts


1 Department of Prosthodontics, Faculty of Dentistry, Necmettin Erbakan University, Konya, Turkey
2 Department of Endodontics, Faculty of Dentistry, Necmettin Erbakan University, Konya, Turkey
3 Department of Pediatric Dentistry, Faculty of Dentistry, Necmettin Erbakan University, Konya, Turkey

Date of Acceptance13-Nov-2017
Date of Web Publication09-Mar-2018

Correspondence Address:
Dr. A R Tuncdemir
Faculty of Dentistry, Necmettin Erbakan University, Karacigan District, Ankara Street, Number: 74/A Karatay-Konya
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_425_16

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   Abstract 


Context: Bond strength of fiber posts. Aims: The purpose of this study was to evaluate the effect of different Post Surface treatment techniques on the push-out bond strength of the quartz fiber posts. Subjects and Methods: A total of 30 maxillary central incisors were decoronated at cementoenamel junction. Root canals were filled and postspaces were prepared. The specimens were classified into three groups according to the surface treatment performed to the postsurface (n = 10) as no surface treatment (control group) (Group 1), A 50-μm aluminum-oxide airborne-particle abrasion group (Group 2), femtosecond laser (FS) group (Group 3). A self-curing adhesive cement was used for cementation of posts. Six sections (two coronal, two middle, and two apical) of 1-mm thickness specimens were prepared with a slow speed diamond saw. Specimens were stored in distilled water at 37°C for 24 h. Then, push-out test was performed on a universal testing machine. Results: The data were analyzed by one-way ANOVA (α = 0.05). The test results indicated that push-out test values significantly different according to surface treatments among groups (P < 0.05). There were no significant differences between root sections of each group for bond strength (P > 0.05). All dislodged Group 3 posts were free of cement, indicating adhesive failure, Group 1 and 2 were partially coated with cement, indicating a mixed failure at the cement/postsurface. Conclusions: Based on the results, aluminum-oxide airborne-particle abrasion group showed higher and FS irradiation group showed lower bond strength values. Push-out bond strength values of the root segments were the same in all groups.

Keywords: Bond strength, femtosecond laser, quartz post, resin cement


How to cite this article:
Tuncdemir A R, Buyukerkmen E B, Celebi H, Terlemez A, Sener Y. Effects of Postsurface Treatments Including Femtosecond Laser and Aluminum-oxide Airborne-particle Abrasion on the Bond Strength of the Fiber Posts. Niger J Clin Pract 2018;21:350-5

How to cite this URL:
Tuncdemir A R, Buyukerkmen E B, Celebi H, Terlemez A, Sener Y. Effects of Postsurface Treatments Including Femtosecond Laser and Aluminum-oxide Airborne-particle Abrasion on the Bond Strength of the Fiber Posts. Niger J Clin Pract [serial online] 2018 [cited 2021 Nov 29];21:350-5. Available from: https://www.njcponline.com/text.asp?2018/21/3/350/226972




   Introduction Top


Endodontically treated teeth, which have lost a large amount of their constitution generally need placement of a post in the root canal to provide retention for restoration and tooth function.[1] In recent years, the increasing demand for esthetic posts and cores has led to the development of metal-free post-and-core systems, especially zircon dioxide and fiber-reinforced composite (FRC) posts. FRC posts reduce the risk of tooth fractures and save the teeth more survival than zirconia posts[2] because of their modulus of elasticity is similar to dentin, minimizing stress transmission to root canal walls.[3] It is believed that FRC posts have additional advantages such as provide superior biocompatibility, mechanical strength, corrosion resistance, easier removal, and esthetics compared to other types of posts.[4]

The main reason for long-term clinical failures of postendodontic restoration is loss of retention.[5] FRC postretention depends on the strength of the chemical and micromechanical interaction among the post, dentin, and resin cement.[6] Failure of the restorations generally occurs at the postcement junction on FRC posts.[7]

Laser surface treatments are becoming increasingly popular in dentistry.[8] Different lasers such as nanosecond Nd:YAG laser, copper vapor laser, excimer laser, Nd:YAG laser and femtosecond laser (FS) have been used to change surface structures.[9] Laser surface treatment needs less time than the conventional acid-etching procedure.[10],[11] Beside these advantages, undesired thermal side effects and mechanical deficiencies were reported as the disadvantages of lasers in most cases.[12] The Nd:YAG laser is known for producing microcracks and fissures as a result of its thermal effects. In addition, studies on popular hard tissue ablation lasers, Er:YAG and CO2 lasers, also reported flaky structures and fine cracks observed on the enamel surface after irradiation.[13]

FS laser was developed in the 1980s and is a laser with 10−15 seconds pulse width and different pulse energies.[14] It has recently been introduced in medical clinics and dental applications, and it is a newer technology than other lasers, such as Er:YAG and Nd:YAG. Some studies have shown that these lasers can provide a precise and clear surface without heating.[15],[16] In addition, this technique can ablate material in the thin surface layer without disturbing the material properties.[17] and these properties make them good materials for use in dental applications. Lorenzo et al. roughened enamel surfaces with an FS laser; they concluded that it improved the bond strength of the bracket to the enamel surface.[18]

Surface treatment of the postinfluences the retention of a post.[19] There are some studies about surface treatments and effects of their results about FRC posts, but there is no information about the etching performance of FS on fiber posts for bonding performance in the literature. The aim of this in vitro study was to compare the different surface treatment technique for bond strengths of fiber posts.

The null hypothesis of this research was that no significant differences would be found among push-out bond strength values after different surface treatment technique.


   Subjects and Methods Top


The power analysis was established by SPSS version 21, IBM, Chicago, IL, USA) (Franz Faul Universitat, Kiel, Germany) software. Based on the 1:1 ratio between groups, a sample size of 30 samples per group would give more than 80% power to detect significant differences with a 0.94 effect size and at the α = 0.05 significance level.

A total of 30 maxillary central incisors with similar size and shape were collected. The specimens were stored distilled water at room temperature. Selection criteria also included the absence of root caries, restorations, or previous endodontic treatment. The root surfaces were cleaned from debris using periodontal scalers. Teeth were decoronated at cementoenamel junction and were endodontically treated. The canals were prepared with a rotary system (X-Smart, Dentsply, Maillefer). All teeth were instrumented using a set of rotary instrument (ProTaper, Dentsply, Switzerland) to the size F3 (multi tapered #30; finishing file) by the same operator. The root canals were irrigated with 1 mL of 2.5% NaOCl. Moreover, 1 mL of 17% ethylenediaminetetraacetic acid alternately after each file change. Final flash was performed with 2 mL of saline and then dried with paper points. All teeth obturated with gutta-percha F3 (Dentsply, Maillefer) and a resin sealer (AH-26, Dentsply DeTrey GmbH, Konstanz, Germany). Provisional filling material (Cavit G, 3M Espe, Seefeld, Germany) was used to seal the coronal orifice. After cementation, the specimens were stored in water at room temperature for a week. Then postspaces were prepared for quartz fiber posts (D. T. LIGHT-POST, Bisco, USA). The specimens were classified into three groups according to the surface treatment performed to the postsurface.

  • Group 1: No surface treatment
  • Group 2: A 50-μm aluminum-oxide (Al2O3) airborne-particle abrasion for 5 s (20-mm distance, 2.5 bar) for each postsurface
  • Group 3: FS laser.


FS laser pulses from an amplifier (Integra-C3.5; Quantronix, New York, USA) were applied 12 s to a postsurface.

FS laser parameters were as follows. The laser delivered a 500 mW/pulse and maching speed 30, skip speed 1250, and a 10 kHz repetition rate.

Two sides of posts made triple rectangular hatch, and other two sides quad-rectangular hatch [Figure 1].
Figure 1: Rectangular hatchs on the postsurface

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The root filling was removed with the D. T. universal drill. The postspace for the largest postsize # 3 was prepared with matching drill of the postsystem. A self-curing adhesive cement (Multilink Automix, Ivoclar, Vivadent, Liechtenstein) was used for cementation of posts. Excess cement was removed with a scaler. Specimens were stored in lightproof boxes after polymerization for 24 h.

A slow speed diamond saw (Buehler/USA) was used to create 1 mm. Thickness specimens from each root. Six sections (two coronal, two middle, and two apical) of 1-mm thickness specimens were prepared [Figure 2]. Specimens were stored in distilled water at 37°C for 24 h. Then, push-out the test was performed on a universal testing machine (AGS-X, Schimadzu Corp., Kyoto, Japan) at a cross-head speed of 1.0 mm/min until bond failure occurred. The specimens were loaded with a 1 mm. Diameter cylindrical tip in an apical-coronal direction to push-out the posttoward the wider part of the root slice to avoid taper limitation.
Figure 2: Diagrammatic view of specimen for push-out test

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The data recorded as (N) and to express in MPa, the bond strength values were divided by the area of the interface, which was calculated with the following formula: A = 2 πrh (π = 3.14, r is the postradius, and h is the thickness of the specimen in mm).

Data were analyzed with one-way ANOVA.


   Results Top


Normality test was carried out with Kolmogorov–Smirnov and also Shapiro–Wilk tests and ranges were normal for 3 groups (P > 0.05) so that One-Way ANOVA statistical analysis was used for this study and also Tamhane method was used for homogeneity. The one-way ANOVA test result indicated that push-out test values significantly different according to surface treatments applied control, airborne particle abrasion, and FS laser irradiation groups (P< 0.05). Airborne particle abrasion group showed the highest and the FS group showed the lowest push-out bond strength [Table 1]. There were no significant differences between root sections of each group for push-out bond strength (P > 0.05) [Figure 3]. All dislodged FS laser group posts were free of cement and indicating adhesive failure, control and Al2O3 airborne-particle abrasion group posts were partially coated with cement, indicating a mixed failure at the cement/postsurface.
Table 1: One-way analysis of variance

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Figure 3: Graphical presentation of estimated marjinal means of the root sections

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   Discussion Top


The hypothesis tested that research was that no significant differences would be found among push-out bond strength values after different surface treatment technique was rejected. Aluminum-oxide airborne-particle abrasion was affect the postretention positively on the other hand FS ablation affect it negatively.

The quartz fiber postsystem is a radiopaque translucent fiber post with unidirectional 60% glass fibers embedded in an epoxy resin matrix. Ingredient of the fiber post is an important factor affecting the bond strength between the fiber post and the resin cements.[20] In addition, the metal-free postrestoration eliminates the potential hazards of corrosion and allergic hypersensitivity.[21] Therefore, this postsystem was used for this study.

Hydrofluoric acid etching has corrosive effect on the glass phase of the ceramic matrix[22] so it can lead to damage on the glass fiber's surface. Therefore it did not used for roughing of the postsurface.

According to studies[23] postsurface treatment with Al2O3 particles did not significantly improve the bond strength between posts and resin. This result is not consistent with this study. Airborne-particle abrasion was applied with 50-μm alumina particles at 2.5-bar pressure for 5 s from a distance of 30 mm for that study.In vitro studies have shown that quartz fiber posts are stronger than other fiber posts[24] and more fatigue resistant than prefabricated metal posts or other fiber posts.[25] According to another study sandblasting abrasion with 50 μ alumina particles at a specific distance, pressure, and time was the only surface treatment in DT light post and transluma post that increased the bond strength to dual cure resin composite cores[26] Therefore, airborne-particle abrasion was applied in the same bar pressure and time but from 20 mm distance for this study because of shortening the distance may effect to surface roughness and by this way increase to bond strength of the fiber posts.

The laser-etching technique is one of the most promising alternative applications for researchs. Various lasers have been used for the surface etching since the first application of lasers in the dentistry.[27],[28] Drawbacks on studies motivated the authors for novel techniques or method. Unlike other laser systems, FS laser systems produce circular shape laser beam. When the laser beam contacts to surface of object, an ablation occurs as a circular shape. Laser ablation did not improve the bond strength between posts and resin for this research. Lorenzo et al. have a study about etching with FS s for metal brackets and revealed that an FS laser without the supporting acid application could have satisfying results.[18] According to scanning electron microscope results, Al2O3 airborne-particle abrasion group is more roughened on the other hand FS laser group less roughened than control group. It may because of FS laser dissolve the FRC epoxi resin matrix [Figure 4]. This can be lead to the lowest bond strength of FS laser group. Therefore, other future studies evaluating different FS laser settings for fiber posts are needed.
Figure 4: Scaning eletron microscope photograph of airborne particle abrasion, control and femtoseond laser groups (Original, ×200)

Click here to view


The resin cement using for postcementation significantly increase posts retention and fracture resistance of the tooth according to other cements.[29],[30] Fiber posts generally luted with a resin cement to increase their bond strength and improve the mechanical performance of the restoration.[31] Therefore, resin cement was used for this study.

In some studies, there is a statistical differences among the cervical middle and apical root sections of the roots[32],[33] on the other hand there is no statistical differences observed about bond strength among the root segments for this study. There are numerious technical drawbacks for achieving to bond strength of the post throughout to root parts. The bonding material's insufficient polymerization or nonuniform adaptation may be prevent the formation of equal bond strengths on root dentin sections. Controlling to moisture and removing to dental remmnants is difficult in postspace.[34],[35],[36] These are related to difficult access to the postspace during handling.[37] In addition, luting cement pollymerization stresses can be confined postspaces because of the inappropriate cavity configuration which obstruct the flow of the cement during settings.[38],[39] These factors may be responsible for the lower bond strengths achieved by the luting agents in the middle and apical root sections for that studies.

A limitation of this study was that different settings of the FS laser can be conducted for postsurfaces and testing metal postgroups could extend the findings of this study as could comparing fiber groups.


   Conclusions Top


Within the limitations of this study, the following conclusions were drawn:

  1. Based on the results presented, push-out test values differed significantly according to the postsurface treatment system. Al2O3 airborne-particle abrasion group showed higher and FS laser group showed lower bond strength values for quartz fiber posts
  2. Push-out bond strength values of the root segments (cervical, middle, and apical) were the same in all groups
  3. The clinical significance of this study was that a 500 mW/pulse and maching speed 30, skip speed 1250, and a 10 kHz repetition rate FS irradiation applied on quartz fiber posts negative affect on push-out bond strengths of the root surfaces. Sufficient studies do not exist about FS laser treatment on dental materials especially fiber posts. Therefore more comprehensive studies using different settings of the FS laser needed to improve bond strength of the quartz fiber posts.


Financial support and sponsorship

This study was supported by Necmettin Erbakan University, Scientific Research Section.

Conflicts of interest

There are no conflicts of interest.



 
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