|Year : 2021 | Volume
| Issue : 12 | Page : 1841-1845
Pull-out bond strength of fiber post luted with two types of resin luting cements using different light curing units
MK AlMadi1, A Khabeer1, S AlHilal2, AS AlShahrani3, S Ali4
1 Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
2 AlSha'alaniyah Primary Care Center, Ministry of Health, Hail, Saudi Arabia
3 AlNusbah Primary Care Center, Ministry of Health, Tabuk, Saudi Arabia
4 Department of Biomedical Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
|Date of Submission||18-Jan-2021|
|Date of Acceptance||04-Jul-2021|
|Date of Web Publication||09-Dec-2021|
Dr. S Ali
Department of Biomedical Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims: The aim of this study was to evaluate the pull-out bond strength of fiber post when cemented with a self-adhesive dual-cured resin luting cement and a conventional light-cured resin luting cement. In addition, the influence of a light-emitting diode (LED) and halogen (QTH) curing lights on the pull-out bond strength was assessed. Materials and Methods: A total of 40 extracted human teeth were selected. Post-space preparation of 10 mm was done and two types of resin cement i.e. RelyX Unicem (RXU) and variolink esthetic LC (VLE) were used for cementation of a translucent RelyX fiber post. Light activation for 60 s was done with LED and QTH curing units. The pull-out test was performed parallel to the long axis of the tooth and the post at a crosshead speed of 1 mm/min using a universal testing machine. The load required to dislodge each post was recorded in Newton (N). Statistical analysis was done and a value of P < 0.05 was considered statistically significant. Results: The RXU showed a mean (SD) pull-out bond strength of 203.5N (47.1) and 207.3N (31.3) when light activated with LED and QTH curing lights, respectively. For VLE, the mean pull-out bond strength was 78.9N (21.5) and 87.7N (30.7), when light activated with LED and QTH curing lights, respectively. Moreover, LED and QTH curing lights did not influence the pull-out bond strength for both the test materials. Conclusion: It is concluded that a dual-cured resin luting cement should be used for the cementation of fiber post. Further research is required to understand the light transmission of translucent fiber posts.
Keywords: Fiber post, halogen, LED, resin cement
|How to cite this article:|
AlMadi M K, Khabeer A, AlHilal S, AlShahrani A S, Ali S. Pull-out bond strength of fiber post luted with two types of resin luting cements using different light curing units. Niger J Clin Pract 2021;24:1841-5
|How to cite this URL:|
AlMadi M K, Khabeer A, AlHilal S, AlShahrani A S, Ali S. Pull-out bond strength of fiber post luted with two types of resin luting cements using different light curing units. Niger J Clin Pract [serial online] 2021 [cited 2022 Jan 25];24:1841-5. Available from: https://www.njcponline.com/text.asp?2021/24/12/1841/332112
| Introduction|| |
The fiber posts are routinely used in the restoration of endodontically involved treated teeth as they have a modulus of elasticity similar to human tooth dentine and provide a higher bond strength when cemented with an adhesive resin luting cement compared to a post cemented with conventional cement. However, the behavior of resin-based adhesive luting cements regarding the quality of curing and the bond strength due to inadequate light penetration is under-researched. Translucent fiber posts have been used which allow the light to penetrate in the deeper region of the root canal and thus helps in improved polymerization of resin cement, however, inadequate polymerization in the middle and apical regions of the root canal has still been reported. This incomplete polymerization may affect the physical properties of the cement leading to poor bonding and clinical performance.
Multiple studies have reported the success rate ranging between 95% and 99% for teeth restored with fiber post., Moreover, these studies reported debonding of the fiber post as the most frequent cause of failure., The retention of fiber posts not only depends on the bond between the post and the cement but also on depends on the bond formed between the root dentine and the luting cement.,
The impact of various cements on the retention of a post within the root canal has been extensively explored and it has been reported that the resin luting cements provide improved retention of posts compared to other conventional cements., The use of various resin luting cements with their respective bonding systems has been suggested for cementing fiber posts. Several studies have shown conflicting results related to the bond strengths of luting cement with the fiber post and root dentin., A study performed by Khabeer et al. in 2015 showed no significant difference in the polymerization of a dual-cured and light-cured resin cement at different depths of the root canal. Therefore, the selection of an appropriate resin luting cements the cementation of fiber post plays a critical role in the outcome.
The hypothesis of the study was that the dual-cured resin luting cement will provide superior bond strength compared to light-cured resin luting cement. Another hypothesis was that the bond strength will be similar when either LED or QTH curing units will be used for the curing of luting cement.
| Materials and Methods|| |
The ethical approval was obtained from the research committee of the college of dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia. A total of 40 human maxillary central incisors teeth extracted for periodontal or orthodontic reasons were collected and visually examined for any fractures, caries, and resorption. The teeth were cleaned of any debris, calculus or soft tissues, and disinfection was done by storing the teeth in sodium hypochlorite solution until use. The teeth were decoronated 1 mm above the cementoenamel junction (CEJ) using a diamond disk mounted on Isomet precision cutting machine (Beuhler Isomet, Beuhler Ltd., Lakebluff, IL, USA), followed by root canal preparation utilizing a step-back technique with ISO stainless steel files (Mani, Matsutani Seisakusho Co., Takanezawa-Machi Tochigi-Ken, Japan), divided into 10 samples per group. The teeth were obturated with guttapercha cones (Sure-Endo, Sure Dent Corp., Seoul, Korea) using lateral condensation technique and a resin-based AH 26 sealer (Dentsply, Surrey, United Kingdom), while the access cavity was sealed with a glass ionomer restorative cement. The teeth were stored in artificial saliva (AS) for 7 days before post placement. The composition of AS was NaCl and KCl (0.400 g), NaH2PO4. H20 (0.69 g), CaCl2.H20 (0.79 g) and Na2S (0.005 g). It was adjusted to pH of 7 by adding 1 M of NaOH. The ethical approval was obtained from ethics and research committee of college of dentistry Imam Abdulrahman Bin Faisal University, Dammam on 31-Jan-2108 with EA Number: 2018013.
The guttapercha was removed with a heated instrument and gates glidden, followed by post space preparation of 10 mm using RelyX post drill (Size 2; diameter 1.6 mm). Translucent RelyX fiber post (3M, ESPE, USA) were cemented using a self-adhesive dual-cured resin luting cement (RXU; RelyX unicem, 3M ESPE, USA) and a conventional light-cured resin luting cement (VLE; Variolink esthetic LC, Ivoclar Vivadent, Schaan, Liechtenstein), followed by light activation for 60 s using a light-emitting diode (LED; Elipar S10, 3M ESPE, USA) and a halogen (QTH; QHL 75, Dentsply, Milford, DE, USA) curing units [Table 1].
The teeth were placed in acrylic resin blocks with the tooth/post extruding from the block. Resin composite was added to the coronal end of the posts to reinforce the grip while performing the test. The pull-out test was performed parallel to the long axis of the tooth and the post at a crosshead speed of 1 mm/min using a universal testing machine (Instron, United Kingdom) and the force (N) required to de-bond the post was recorded. Data were collected and statistical analysis (SPSS 20.0, IBM product, Chicago, USA) was done utilizing analysis of variance (ANOVA) and post hoc LSD tests. A value of P < 0.05 was considered statistically significant.
| Results|| |
The mean (SD) of the pull-out test for RXU when light activated using LED and QTH curing units was 203.5N (47.1) and 207.3N (31.3), respectively, while for VLE, the pull-out test showed a mean (SD) of 78.9N (21.5) and 87.7N (30.7) when light activated with LED and QTH curing units, respectively. The mean (SD) of pull-out tests is also shown in [Table 2]. It can be observed that RXU showed significantly superior bong strength compared to VLE resin luting cement (P < 0.05). However, no statistically significant difference was found when the cements were light-activated using LED and QTH curing units (P > 0.05) [Figure 1].
|Table 2: Showing the mean (±SD) pull-out bond strength for RelyX fiber post when cemented with a dual-cured RelyX unicem resin luting cement and a light-cured Variolink esthetic LC resin luting cement using a LED and a QTH curing units. (n=10)|
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|Figure 1: Comparison between the mean (±SD) pull-out bond strength for RelyX fiber post when cemented with a dual-cured RelyX unicem resin luting cement and a light-cured Variolink esthetic LC resin luting cement using a LED and a QTH curing units. (n = 10)|
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| Discussion|| |
The hypothesis of the study that the dual-cured resin luting cement will provide a superior bond strength compared to a light-cured resin luting cement was accepted. Moreover, the other hypothesis was also accepted as both the LED and QTH did not show any influence on the pull-out bond strength of the tested cements.
According to this study, RXU showed superior bond strength compared to VLE resin luting cement. This suggests that the RXU cement undergoes chemical curing in the absence of light leading to higher bond strength. A study done by Giachetti et al. in 2004 reported no significant difference between the bond strength of a dual-cured and light-cured resin luting cement. They reported a mean bond strength of 301.4N for dual-cured cement and 275.2N for light-cured cement. In the present study, the mean bond strength for the dual-cured RXU cement was 203.5N–207.3N, while for the light-cured VLE cement, it was 78.9–87.7N. These discrepancies can be attributed to the type of cement, the type of the fiber post, the type of curing light and the testing technique used. The present study used light-cured VLE cement which according to the manufacturer is not recommended to be used as a fiber post luting cement. However, due to the light-transmitting properties of the translucent fiber post as claimed by the manufacturer, it was used for research purposes. A study done by Khabeer et al. in 2015 reported that the polymerization of a dual-cured and a light-cured resin luting cement in the apical third of the root canal was inferior compared to the coronal region. This indicates that the translucent fiber posts are not entirely effective in conducting the light from the coronal aspect of the fiber post to the deeper apical regions. Another explanation for the lower bond strength of the light-cured VLE cement used in the study could be attributed to the poor bond with dentine as this cement is recommended to be used for veneer placement and might be more suitable to form a stronger bond with enamel.
A study conducted by Webber et al. in 2015 used a dual-cured cement (RelyX U200) which is similar to the dual-cured cement used in the present study (RXU). However, they reported a poor bond strength of 103.1N compared to the present study, which could be due to the use of bovine teeth in the study performed by Webber et al. In contrast, another study conducted by Macedo et al. in 2010 assessed the bond strength of fiber post luted with RelyX unicem. They reported a higher bond strength of 265.8N compared to this study and this could be attributed to the use of a parallel fiber post (Reforpost Glass Fiber) compared to the present study which used a tapered fiber post.
This study utilized the pull-out test as it has been shown to be a reliable method to evaluate the bond strength between the root dentine and the post.,, Moreover, the shear forces applied through the pull-out test are comparable to the forces found clinically.,
This study used two types of light-curing units. It has been reported that LED provides a higher intensity compared to QTH curing lights which might affect the degree of conversion and bond strength of luting cements in the deeper root canal regions. However, it has also been shown that LED curing lights to have a narrow wavelength compared to QTH curing lights and might not be able to adequately activate the initiators and co-initiators present in the cements resulting in a poor degree of conversion and bond strengths. Therefore, LED and QTH curing units were used in this study to evaluate their potential influence on the cements.
| Conclusion|| |
It can be concluded that a dual-cured resin luting cement should be used for fiber post cementation, while a light-cured resin luting cement should be avoided as they may lead to inadequate bond strength leading to failure. Moreover, according to this study, LED and QTH curing lights do not influence the pull-out bond strength. Further research is required to fully understand the light transmission of translucent fiber posts.
One of the limitations of the study could be the use of a smaller diameter fiber post and the results might not correspond to the use of light-cured and dual-cured resin luting cements with a larger diameter fiber post. Moreover, the placement technique could also have an influence as during the placement of the luting cements and fiber posts, there might be incorporation of voids or bubbles which might adversely affect the pull-out bond strength.
Dual-cured resin luting cement should be used for fiber post cementation.
Light-cured resin luting cement should be avoided as they may lead to inadequate bond strength which may lead to failure.
LED and QTH curing lights do not influence the pull-out bond strength.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]