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Table of Contents
ORIGINAL ARTICLE
Year : 2018  |  Volume : 6  |  Issue : 4  |  Page : 49-53

Impact of different laser treatments on push-out strength of post luted with resin cement: An in vitro study


1 Department of Prosthodontics, Sree Anjaneya Institute of Dental Sciences, Modakallur, Atholi, Kozhikode, India
2 Department of Conservative Dentistry and Endodontics, Sree Anjaneya Institute of Dental Sciences, Modakallur, Atholi, Kozhikode, India
3 Department of Conservative Dentistry and Endodontics, Mar Baselios Dental College, Kothamangalam, Kerala, India
4 Department of Oral and Maxillofacial Surgery, Bhabha College of Dental Sciences, Bhopal, Madhya Pradesh, India
5 Department of Orthodontics, Government Dental College, Calicut, Kerala, India

Date of Web Publication14-May-2019

Correspondence Address:
Dr. Sylvana Achammada
Department of Prosthodontics, Sree Anjaneya Institute of Dental Sciences, Modakallur, Atholi, Kozhikode, Kerala.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/INJO.INJO_14_18

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  Abstract 

Background: The interface of the post and resin cement is a site of likely failure of adhesion. This interface adhesion of the post surface can be improved through different pretreatments such as laser. So the aim of this study was to investigate the effects of erbium-doped yttrium aluminum garnet (Er:YAG) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation on the push-out bond strengths of fiber-reinforced composite (FRC) posts and resin cement. Materials and Methods: Thirty extracted mandibular premolar teeth were taken and randomly divided into three groups, Group 1 (control group), Group 2 (Er,Cr:YSGG), and Group 3 (Er:YAG). FRC post cementation was performed with Etch-and-rinse resin cement. Push-out strength was tested using a universal materials tester. Statistical analysis was carried out using Statistical Package for the Social Services (SPSS), version 20. Results: Highest push-out bond strength was observed in Group 3 (i.e., Er:YAG, 18.1±0.4MPa) followed by Group 2 (i.e., Er,Cr:YSGG, 17.6±0.9MPa) and least strength was seen in Group 1 (i.e., control, 14.7±1.5MPa). A statistically significant difference was observed when the groups were compared to the untreated or control group (P = 0.000). Conclusion: It was concluded that laser treatment, that is, Er:YAG and Er,Cr:YSGG, significantly improved the push-out bond strength of FRC posts luted with resin cement.

Keywords: Er,Cr:YSGG, Er:YAG, fiber-reinforced post, push-out strength


How to cite this article:
Achammada S, Thayyil S, Joy J, Divakar N, Sathe S, Sathyanathan S. Impact of different laser treatments on push-out strength of post luted with resin cement: An in vitro study. Int J Oral Care Res 2018;6:49-53

How to cite this URL:
Achammada S, Thayyil S, Joy J, Divakar N, Sathe S, Sathyanathan S. Impact of different laser treatments on push-out strength of post luted with resin cement: An in vitro study. Int J Oral Care Res [serial online] 2018 [cited 2019 Jun 25];6:49-53. Available from: http://www.ijocr.org/text.asp?2018/6/4/49/253705




  Introduction Top


Teeth that are endodontically treated are usually severely broken down by dental decay, previous restorations, or excessive wear, resulting in inadequate coronal tooth structure.[1] The long-term success or failure of restorative treatment or prosthesis of an endodontically treated tooth is based on its clinical adaptation, the quality of the restoration, and the health of the supporting tissue.[2]

So, posts are widely used to restore root canal–treated teeth that have excessive loss of coronal tooth to obtain a core for the classic restoration. Posts are chosen as an alternative method for casting metal post-core systems, considering its advantages over it.[2],[3] It has dependable mechanical properties, such as lower modulus of elasticity that of dentin, which will result in decreased incidence of root fractures.[4],[5]

Fiber posts and composite resin are popular for coronal restoration because they can cut down the restoration procedure, conserve the tooth structure, and have adequate mechanical properties and also they possess adequate aesthetic properties.[6]

Most of the failures involving root canal–treated teeth reconstructed with posts are due to cementation of the posts, whereas root fractures are the most serious type of failure.[7],[8]

Generally, retention is affected by the properties of the cement, the post type, and the cement bond to the post and root canal dentin.[9] Fiber-reinforced composite (FRC) post placement involves the formation of two equally important interfaces, that is, at the dentin/resin composite and resin composite/fiber level, where a failure can eventually occur.[10] Untreated fiber posts have a relatively smooth surface area that limits mechanical interlocking between the resin cement and the post surface.

One of the techniques for surface treatment of posts is laser irradiation.[11] Lasers provide an easy and relatively safe means for altering the surface of materials, and change the wettability characteristics for improved adhesion and bonding.[12] During the past few years, the efficiency of lasers has been studied in the preparation of dental cavities and in the removal of tooth hard tissues and soft tissues.[13] Recently, among other laser systems, the erbium lasers erbium-doped yttrium aluminum garnet (Er:YAG; 2940nm) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG; 2790nm) are frequently used in dental applications and to change the surface conditions of dental materials.

However, there is not enough literature that this system is the best surface-conditioning method for obtaining required bond strength. This laser system, associated with maximal absorption in water and well absorbed in hydroxyapatite, has been designed to remove dentin and the enamel structure effectively.[14],[15] The aim of this study was to investigate the effects of Er:YAG and Er,Cr:YSGG laser irradiation on the push-out bond strengths of FRC posts and resin cement.


  Materials and Methods Top


Thirty extracted mandibular premolar teeth and radiopaque, translucent glass FRC composite posts (Ivoclar Vivadent, India) were taken for this study. The surfaces of the fiber posts were cleaned in accordance with the manufacturer’s instructions, and they were randomly allocated into three groups, according to the type of surface treatment, as follows:

  • Group 1: No treatment or control group.
  • Group 2: Er,Cr:YSGG laser irradiation. The laser equipment used was a Waterlase Millenium system (Biolase Technologies, San Clemente, California); the output power was 0.75 W and water/air flow of 24% and 34%, respectively. The focal area of the tip was 320 μm2.
  • Group 3: Er:YAG laser irradiation. Surface treatment was performed with Er:YAG laser (MetaLaser, Shanghai, China).


Post cementation

Etch-and-rinse resin cement (Single Bond/RelyX ARC; 3M ESPE, St Louis, Missouri): Intracanal dentin was etched with 37% phosphoric acid for 15s, rinsed with distilled water for 15s, and then gently dried with absorbent paper points. After etching the dentin, the cement was inserted into the root canal and the fiber post was inserted and excess cement was removed.

An additional 40s of light polymerization was performed to ensure optimal polymerization of the luting agent. After 24h of storage in distilled water, each specimen was mounted on the holding device of a low-speed saw (Isomet, Buehler, Lake Bluff, Illinois) and cut perpendicular to the long axis of the post. Fiber posts have double tapers at the middle and apical parts of their design. The parallel sections of the posts were used to simplify calculation of the surface area. Two disks (2-mm thick) were obtained from each sample, and each group therefore consisted of a 12-disk sample. Slices were examined with stereomicroscope (Novex, Arnhem, Holland) at ×20 magnification to determine the surface area of the inner part of the slices.

The push-out test was carried out with the help of the universal testing machine (TLCLO, Dartec, Stourbridge, England) at 1mm/min crosshead speed, in an apical-coronal direction using a pin (diameter, 1.0mm) at center of the apical aspect of the post surface, without stress on the surrounding post space walls. The maximum force (N) required to force out the post from the root slice was recorded. Bond strength was expressed in megapascal (MPa), the load at failure (N) was divided by the area of the bonded interface, which was calculated with the following formula:



where, π is the constant 3.14, r1 is the coronal post radius, r2 is the apical post radius, and h is the thickness of the slice in millimeters.

The remaining posts from each group were mounted and observed under a scanning electron microscope at ×3000 magnification.

Statistical analysis

The collected data were analyzed using one-way analysis of variance and Tukey’s post hoc tests (P = 0.05) in Statistical Package for the Social Sciences (SPSS) software, version 20 (IBM SPSS Inc, Chicago).


  Results Top


The mean and standard deviations of the push-out bond strength values are presented in [Table 1]. The highest push-out bond strength was observed in Group 3 (i.e., Er:YAG, 18.1±0.4MPa) followed by Group 2 (Er,Cr:YSGG, 17.6±0.9MPa), and the least strength was seen in Group 1 (i.e., control, 14.7±1.5MPa). A statistically significant difference was observed when the groups were compared to the untreated group (P = 0.000). As seen in [Table 2], no significant difference was observed between Groups 2 and 3.
Table 1: Mean push-out values and standard deviation

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,
Table 2: Comparison of mean push-out strengths between the groups

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On scanning electron microscope examination, FRC posts of Groups 2 and 3 appeared to be significantly more micro-retentive than Group 1 [Figure 1]A–C].
Figure 1: Scanning electron microscope images of the fiber post surfaces after different treatments. (A) Untreated. (B) Er,Cr:YSGG. (C) Er:YAG

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  Discussion Top


This in vitro study was conducted with the aim to investigate the effects of Er:YAG laser irradiation on the push-out bond strengths of FRC posts and resin cement.

Since the beginning of 1990s, prefabricated glass FRC posts have been used with the introduction of carbon fiber posts. In an attempt to improve aesthetics, further types of FRC posts were developed, which led to the development of glass or white-quartz fibers and translucent resinous matrices. FRC posts are essentially composite materials composed of fibers of silica bounded by a matrix of polymer resin, generally an epoxy resin. As FRC posts are translucent, they have aesthetic advantages. Currently, a wide variety of FRC posts are available with different shapes, sizes, and tapers. FRC posts also more strongly match the modulus of elasticity of root dentin, and multiple in vitro studies showed that the posts distribute occlusal stresses more evenly in the root dentin, usually leading to fewer and less-catastrophic root fractures, which are often repairable.[16],[17

Fiber posts have a comparatively smooth surface area if it is unprocessed],[ which restricts mechanical interlocking between the post surface and the resin cement. Consequently],[ multiple surface pretreatment methods have been tested to overcome the unreactivity of the FRC post surface. One of the techniques of surface treatment of post is laser irradiation. In spite of all these advantages],[ fiber posts have several lacunas. One of problem that causes failure at the post retained restorations is debonding. Restorations carried out with the support of FRC posts fail due to dislodgment of the posts most commonly at the post adhesive junction.[9] FRC posts are commonly composed of a polymer resin matrix that is epoxy resin that has a highly cross linked structures and high degree of conversion, reinforced by carbon, zirconia, quartz, glass, or silica fibers. The polymer matrix in the structure of the FRC post is virtually not capable to react with the monomers of resin cements. Prior to the cementation process, optimal post surface treatments could potentially improve the bond strength of the post and cement interface due to changes in the matrix of the fiber posts.[18],[19]

Various testing methods were introduced to assess the retention of bonding agent adhesion to posts and tooth surface. The push-out test used in this study shows clinical conditions compared with the pull-out test. In comparison with the micro-tensile test, the push-out test has shown more reliable values in measuring the bond strength of the posts. No impulsive failure occurred with the push-out test but premature failures occurred frequently in the micro-tensile method. Further homogenous stress distribution and lower data variability have been observed compared with the micro-tensile test. In addition, preparing the specimens and performing the test are easy; regional differences between root dentin levels can be evaluated with this method. The push-out test is one of the key tools for evaluating fiber post bonding. Thus, we used this method.[20],[21]

This study found out that the highest push-out bond strength was observed in Group 3 (i.e., Er:YAG, 18.1±0.4MPa) followed by Group 2 (Er,Cr:YSGG, 17.6±0.9MPa) and the least strength was seen in Group 1 (i.e., control, 14.7±1.5MPa). A statistically significant difference was observed when the groups were compared to the untreated or control group (P = 0.000); however, no statistically significant difference was observed between Group 3 and 2, that is, Er:YAG and Er,Cr:YSGG.

Results were in accordance with the studies by Oliveira et al.,[22] which showed root surfaces irradiated with Er:YAG and Er,Cr:YSGG lasers presented greater roughness than those in the control group. Also in a study by Arslan et al.,[23] bond strength was better in air abrasion and Er:YAG groups compared to that in control group.

In contrast to this study, the study by Bandéca et al.[24] showed Er,Cr:YSGG laser irradiation did not influence the bond strength of the resin cements, and the study by Kurt et al.[8] showed the lowest bond strength in the Er:YAG 500-mJ group (6.14±0.94MPa).


  Conclusion Top


Within the limits of this study, it was concluded that laser treatment, that is, Er:YAG and Er,Cr:YSGG, significantly improved the push-out bond strength of FRC posts luted with resin cement. Further studies should be carried out with different types and parameters of laser devices to know more about its effect on push-out bond strength.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Adanir N, Belli S. Stress analysis of a maxillary central incisor restored with different posts. Eur J Dent 2007;1:67-71.  Back to cited text no. 4
    
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Kemaloglu H, Emin Kaval M, Turkun M, Micoogullari Kurt S. Effect of novel restoration techniques on the fracture resistance of teeth treated endodontically: An in vitro study. Dent Mater J 2015;34:618-22.  Back to cited text no. 6
    
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Kurt M, Guler AU, Duran I, Uludamar A, Inan Z. Effects of different surface treatments on the bond strength of glass fiber-reinforced composite root canal posts to composite core material. J Dent Sci 2012;7:20-5.  Back to cited text no. 8
    
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Albashaireh ZS, Ghazal M, Kern M. Effects of endodontic post surface treatment, dentin conditioning, and artificial aging on the retention of glass fiber-reinforced composite resin posts. J Prosthet Dent 2010;103:31-9.  Back to cited text no. 9
    
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Radovic I, Monticelli F, Cury AH, Bertelli E, Vulicevic ZR, Ferrari M. Coupling of composite resin cements to quartz fiber posts: A comparison of industrial and chairside treatments of the post surface. J Adhes Dent 2008;10:57-66.  Back to cited text no. 10
    
11.
Monticelli F, Osorio R, Sadek FT, Radovic I, Toledano M, Ferrari M. Surface treatments for improving bond strength to prefabricated fiber posts: A literature review. Oper Dent 2008;33:346-55.  Back to cited text no. 11
    
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Usumez A, Inan O, Aykent F. Bond strength of a silicone lining material to alumina-abraded and lased denture resin. J Biomed Mater Res B Appl Biomater 2004;71:196-200.  Back to cited text no. 12
    
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Schoop U, Goharkhay K, Klimscha J, Zagler M, Wernisch J, Georgopoulos A, et al. The use of the erbium, chromium:yttrium-scandium-gallium-garnet laser in endodontic treatment: The results of an in vitro study. J Am Dent Assoc 2007;138:949-55.  Back to cited text no. 13
    
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Dederich DN, Bushick RD; ADA Council on Scientific Affairs and Division of Science; Journal of the American Dental Association. Lasers in dentistry: Separating science from hype. J Am Dent Assoc 2004;135:204-12; quiz 229.  Back to cited text no. 14
    
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Diaci J, Gaspirc B. REVIEW comparison of Er:YAG and Er,Cr:YSGG lasers used in dentistry. J Laser Health Academy 2012;1:1-13.  Back to cited text no. 15
    
16.
Monticelli F, Ferrari M, Toledano M. Cement system and surface treatment selection for fiber post luting. Med Oral Patol Oral Cir Bucal 2008;13:E214-21.  Back to cited text no. 16
    
17.
Ferrari M, Vichi A, Grandini S, Goracci C. Efficacy of a self-curing adhesive-resin cement system on luting glass-fiber posts into root canals: An SEM investigation. Int J Prosthodont 2001;14:543-9.  Back to cited text no. 17
    
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Bateman G, Ricketts DN, Saunders WP. Fibre-based post systems: A review. Br Dent J 2003;195:43-8; discussion 37.  Back to cited text no. 18
    
19.
Schmage P, Cakir FY, Nergiz I, Pfeiffer P. Effect of surface conditioning on the retentive bond strengths of fiber reinforced composite posts. J Prosthet Dent 2009;102:368-77.  Back to cited text no. 19
    
20.
Cekic-Nagas I, Ergun G, Nagas E, Tezvergil A, Vallittu PK, Lassila LV. Comparison between regional micropush-out and microtensile bond strength of resin composite to dentin. Acta Odontol Scand 2008;66:73-81.  Back to cited text no. 20
    
21.
Goracci C, Tavares AU, Fabianelli A, Monticelli F, Raffaelli O, Cardoso PC, et al. The adhesion between fiber posts and root canal walls: Comparison between microtensile and push-out bond strength measurements. Eur J Oral Sci 2004;112:353-61.  Back to cited text no. 21
    
22.
Oliveira GJ, Theodoro LH, Marcantonio Junior E, Sampaio JE, Marcantonio RA. Effect of Er,Cr:YSGG and Er:YAG laser irradiation on the adhesion of blood components on the root surface and on root morphology. Braz Oral Res 2012;26:256-62.  Back to cited text no. 22
    
23.
Arslan H, Ayranci LB, Kurklu D, Topcuoglu HS, Barutcigil C. Influence of different surface treatments on push-out bond strengths of fiber-reinforced posts luted with dual-cure resin cement. Niger J Clin Pract 2016;19:218-22.  Back to cited text no. 23
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24.
Bandéca MC, Pinto SCS, Calixto LR, Saad JRC, Barros ELD, Shelb A. Influence of Er,Cr:YSGG laser on bond strength of self-adhesive resin cement. Materials Research 2012;15: 491-4.  Back to cited text no. 24
    


    Figures

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    Tables

  [Table 1], [Table 2]



 

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