Influence of laser irradiation on the push-out bond strength between a glass fiber post and root dentin

Contemporary Concepts of Adhesive Cementation of Glass-Fiber Posts: A Narrative Review

(1) Background: Cementation of glass fiber posts to root canals has been associated with various failures, especially debonding. This narrative review aims to present the contemporary concepts concerning the adhesive cementation of glass fiber post and to discuss the optimal management of these factors. (2) Methods: Electronic search was performed in MEDLINE/Pub Med and Google Scholar using selected keywords examining the parameters post length, surface treatment of glass fiber posts, post space preparation and dentin pretreatment, resin cement selection, adhesive systems and hybrid layer formation, and clinical techniques. (3) Results: The search led to the selection of 44 articles. Epoxy resin-based endodontic sealers are recommended and the use of temporary cement in the root canal should be avoided. The minimum length of a glass fiber post adhesively cemented to a root canal is 5 mm. Irrigating the root canals with chlorhexidine, MTAD, or EDTA (alone or in combination with NaOCl) after post space preparation seems to enhance the bond strength. Silane application on the surface of the post seems to be beneficial. Concerning resin cements and adhesive systems, the results were rather inconclusive. Finally, resin cement should be applied inside the root canal with an elongation tip and photoactivation should be delayed. (4) Conclusions: Contemporary concepts of adhesive cementation of glass fiber posts can indeed improve the bond between glass fiber posts, resin cement, and root canal dentin, however, evidence coming from long-term randomized prospective clinical trials is needed in order to obtain safer conclusions.

Effect of Er:YAG laser on removal of fibre posts from root canal

The aim of this study was to evaluate the efficiency of Er:YAG laser in translucent fibre post removal. 60 human single-rooted anterior teeth were divided into three groups (n = 20) according to post diameters (Exacto1-E1, Exacto2-E2, Exacto3-E3) and subdivided according to laser application. Fibre posts were cemented to endodontically treated teeth, and the specimens were sliced with a thickness of 1.0 ± 0.2 mm. Er:YAG laser was applied and the push out bond strength test was performed. Two-way analysis of variance was used to perform the statistical analysis. Push out bond strengths at apical area were significantly lower in all test groups (p < 0.05). Laser application caused increase in all radicular thirds, but it was significant for E1 and E3 groups. Laser application to the post-dentine interface enhances the connection between post and dentine.

The combined treatment of fiber post and root canal by the Er:YAG laser enhances the bond strength of composite reconstruction

Fiber post bonding failure remains an issue during crown restoration procedures. This experiment examines the bonding effect of combined Er:YAG laser treatment on both root canal and fiber post. Sixty extracted mandibular first premolars were randomly selected and divided into 6 groups (n = 10 per group): G1 (control group): root canal with 2.5% NaClO treatment, no treatment of fiber post; G2: root canal with 2.5% NaClO treatment and fiber post with airborne-particle abrasion; G3: root canal with Er:YAG laser treatment and fiber post with airborne-particle abrasion; G4: root canal with Er:YAG laser treatment, no treatment of fiber post; G5: root canal with 2.5% NaClO treatment, fiber post with Er:YAG laser irradiation; G6: combined Er:YAG laser irradiation of both root canal and fiber post. An Er:YAG laser with a wavelength of 2940 nm was used to treat the fiber post (4.5 W, 450 mJ, 10 Hz for 60 s at 100-μs pulse duration with 100% water cooling) and the root canal (1.5 W, 150 mJ, 10 Hz for 60 s at 100-μs pulse duration with 100% water cooling). When the root canal was treated with the laser, the fiber tip was inserted into the root canal to make a spiral reciprocating motion. Bond strength was analyzed by a micro push-out test. Data were analyzed using both the Tukey test and two-way ANOVA (α = 0.05). Failure modes were observed and counted through a stereo microscope. The root canal and fiber post surface analysis was performed using SEM. The bond strength of G3 and G6 were significantly enhanced compared to those of the other groups (p < 0.05). The SEM analysis showed that the smear layers of groups with root canals subjected to Er:YAG laser irradiation were significantly reduced compared to those of the control group (G1). In groups with fiber posts treated with Er:YAG laser irradiation, the surfaces of the fiber posts exhibited greater surface roughness and a certain degree of epoxy matrix removal. Through the combined Er:YAG laser irradiation of both root canal and fiber post, the bond strength between them was significantly enhanced, which was superior to the individual treatment of either fiber posts or root canal.

Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review

The utilization of lasers has been regarded as a novel technique for the purposes of clinical use in the dental field. Recently, numerous studies have been conducted on the potential applications of laser therapy in endodontics. Moreover, due to their ablation, penetrability, and disinfection capabilities, lasers have performed well with respect to endodontic treatments, including root canal treatment, vital pulp therapy (pulp capping and pulpotomy), dentinal hypersensitivity treatment, and management of dental pain related to pulp and periradicular disease. In particular, the superiorities of laser-aided pulp therapy are emphasized through condensed clinical controlled trials, and histological studies, in this review. Moreover, the ingenious use of laser applications with respect to aiding in the acceleration of root development and the extraction of foreign matters (i.e., broken files and fiber posts) in canals has quickly become the cutting-edge trend of current research. This review offers a summary and discussion of the current literature on all the aforementioned laser applications. Moreover, the characteristics of laser devices, including erbium lasers, neodymium-doped lasers, CO2 lasers, and diode lasers, are detailed and discussed here, providing useful references for laser application in endodontics. We also focus on the different wavelengths with respect to the lasers that are applied in endodontics. High-power lasers perform well as operative instruments; in addition, low-level lasers lead to the regulation of pulp inflammation, and the promotion of pulp healing. This narrative review provides a summary of the advanced applications of lasers in conjunction with various devices in the practice of endodontics, and aims to inspire innovative perspectives on lasers in the context of the treatment of dental diseases, especially pulp diseases, in the future.

Is the Er:YAG laser affect the surface characteristics and bond strength of Y-TZP?

This study evaluated the surface characteristics and bond strength of Y-TZP treated with Er:YAG laser at different focal distances. 120 Y-TZP blocks were divided into five groups (n=24), according to the surface treatment: no treatment (C-); sandblasting with silica-coated aluminum oxide particles (C+); and Er:YAG laser application at focal distances of 1mm (Er:YAG-1), 4mm (Er:YAG-4), and 7mm (Er:YAG-7). Surface characteristics were analyzed using Vickers microhardness, confocal laser microscope, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). For the bond strength test, 100 Y-TZP blocks were subdivided into two subgroups (n=10), according to the resin cement used: with (MDP+) or without 10-methacryloyloxydecyl dihydrogen phosphate (MDP-). The Vickers microhardness and surface roughness were analyzed by one-way ANOVA and bond strength by two-way ANOVA and Tukey's test for both (α=0.05). Vickers microhardness differences were not observed between the groups (p>0.05); C+ showed higher surface roughness values. SEM images showed micromorphological differences between the groups. The XRD data detected tetragonal crystals for C- and, for the other groups, tetragonal and monoclinic peaks. For bond strength, no statistically difference significance were observed among the cements with or without MDP (p>0.05) but showed significant difference between the surface treatments (C+ > C- = Er:YAG1 > Er:YAG4 = Er:YAG7) (p<0.05). Suggested that the Er:YAG laser cannot replace conventional treatment with aluminum oxide particles and the presence of MDP in the resin cement had no influence on the bond strength.

Surface modification of glass fiber-reinforced composite posts to enhance their bond strength to resin-matrix cements: an integrative review

BACKGROUND

Endodontically treated teeth usually can reveal an extensive loss of dental structure and require the use of intraradicular posts to provide adequate support and retention. Retention of the post depends on the surface treatment of the endodontic post itself and on the root canal dentin as well as on the type of resin-matrix cement.

PURPOSE

The main aim of this study was to conduct an integrative review on the influence of different surface treatment methods of glass fiber-reinfored resin composite (GFRC) posts on their push-out bond strength to resin-matrix cements in endodontically treated teeth rehabiliation.

METHOD

A literature search was performed on PubMed (via National Library of Medicine) regarding articles published within the last 10 years, using the following combination of search terms: "intracanal post" OR "endodontic post" OR "root canal post" OR "intraradicular post" OR "glass fiber" AND "resin cement" AND "adhesion" OR "bond strength" OR "shear bond strength" OR "push out".

RESULTS

Results from the selected studies recorded the highest push-out bond strength around 22.5 MPa) on GFRC posts to resin-matrix cements when the surfaces were pre-treated by grit-blasting with silicate followed by silane conditioning. However, high values of push-out bond strength (21.5 MPa) were also noticed for GFRC posts after etching with hydrogen peroxide followed by silance conditioning. Thus, the highest values of bond strength of endodontic posts to the resin-matrix cements were recorded when a combined physico-chemical approach was assessed. Non-treated surfaces showed the lowest bond strength values between 5 to and 9 MPa. Surface analyses of GFRC posts showed an increased roughness after grit-blasting or etching that promoted a mechanical interlocking of the adhesive and resin-matrix cements.

CONCLUSION

The combined treatment of glass fiber-reinforced resin composite post surfaces by physical and chemical methods can promote the increase in roughness and chemical functionalization of the surfaces prior to cementation., That results in a high mechanical interlocking of the resin-matrix cements and a stable retention of the teeth root intracanal posts.

CLINICAL RELEVANCE

Combining chemical and physical modification methods of surfaces can provide the most promising adhesion-enhancing pathways of GFRC posts to resin-matrix cements, that can decrease the risk of clinical failures by fracture and detachment of endodontic posts.

Efficiency of Erbium-Doped Yttrium Aluminum Garnet Laser in Debonding Cemented Glass Fiber Posts: an in vitro Study

Statement of the Problem:

The efficacy of erbium-doped yttrium aluminum garnet (Er; YAG) laser on the debonding properties of certain post materials has remained largely unexplored.

Purpose:

This study aimed to investigate the effect of Er; YAG laser irradiation on debonding of cemented glass fiber posts in root canal treated teeth.

Materials and Method:

In this in vitro study, forty root canal treated mandibular premolar teeth were used in this study. Glass fiber posts were bonded using Panavia F 2.0 cement in the root canal space, and samples were divided into two groups. In the test group, samples were exposed to laser radiation of 7W, 350mJ, frequency of 20Hz and discontinued washing spray. In the control group, samples were left untouched. In each group, samples were sectioned into 1.5mm thick slices from the coronal, middle, and apical thirds of the root (N=120). Tensile bond strengths were evaluated using the push-out test and the failure patterns were evaluated using scanning electron microscopy (SEM). To compare the laser and non-laser groups at each location, independent sample t test was applied, and to compare bond strength between the locations in each group, one-way ANOVA and Tukey’s HSD post hoc was applied.

Results:

A significant difference in tensile strength was observed between the laser-irradiated group and control group; tensile bond strength was much higher in the control group (p<0.001). The highest frequency of fractures was observed at the cement-dentin interface. Given the used parameters, complete debonding was not achieved in the laser-irradiated group.

Conclusion:

Laser radiation reduced the bond strength of glass fiber posts to resin cement without complete debonding.

Laser Treatment of Fiber Post and Final Push-Out Bond Strength: A Systematic Review and Meta-Analysis

Purpose: This review article tries to answer this question: "What are the effects of laser surface treatment of fiber posts (FPs), compared with other surface roughening methods, on bond strength of cemented FPs?" Methods: Search was carried out in six electronic databases by focusing on defined key words. Related titles and abstracts, up to March 2019, were collected, read, and selected for quality assessments. A total of 2408 articles were included in the study at the initial stage of the searching phase. Results: Finally, seven studies were recognized to be reliable to be reviewed and meta data analysis in the study. All the studies were in vitro with a total of 340 samples. None of the Er:YAG (-0.27, 95% CI: -2.29 to 1.76; p = 0.79) and Er,Cr:YSGG (-0.04, 95% CI: -1.43 to 1.35; p = 0.95) treated samples showed any significant overall mean differences in final push-out bond strength (PBS) compared with the control groups. Conclusions: Laser pretreatment of FP surfaces might not be effective in providing high PBS. FP surface are susceptible to damage of high-level laser irradiation and might show decreased bond strength.

The effect of a root-dentin pretreatment technique combining PIPS with MTAD aiming to improve the bond strength of glass fiber post

The aim of this study was to evaluate the combined effect of MTAD and photon-induced photoacoustic streaming (PIPS) technique on the smear layer removal and the bond strength of glass fiber post. Fifty-five human mandibular premolars were chosen. After root canal therapy and post space preparation, the teeth were equally divided to five groups according to the methods of root-dentin pretreatment: G1: distilled water (control); G2: 2.5% NaOCl+17% EDTA; G3: MTAD; G4: PIPS; G5: MTAD+PIPS. One sample was randomly selected from each group, and scanning electron microscope (SEM) was used to observe the microscopic morphology of the coronal, middle and apical level of the root-dentin. The remaining ten samples from each group were glued to glass fiber posts, and the bond strength was assessed by push-out test. SEM evaluation showed that the most complete smear layer removal was found in MTAD + PIPS group, especially in coronal third. Push-out test results exhibited that there was a statistically significant interaction between the experimental groups and root canal third (p < .0005). Significant differences could be found among five groups (p < .05): G5 > G4 > G3 > G2 > G1. G5 had the highest bond strength. In conclusion, post space pretreatments with MTAD or PIPS technique can significantly remove smear layer and improve the bond strength of glass fiber post, and combination of them works best.

Effects of motion direction and power of Er,Cr:YSGG laser on pull-out bond strength of fiber post to root dentin in endodontically-treated single-canal premolar teeth

BACKGROUND

Inadequate retention and gradual debonding of intracanal post from root dentin is a major cause of failure of endodontically treated teeth restored with fiber post.

MAIN BODY

This study aimed to assess the effect of surface treatment of quartz fiber posts with different powers and motion directions of Er,Cr:YSGG laser on their pull-out bond strength to root dentin in endodontically treated premolar teeth. In this study, 105 fiber posts were divided into 7 groups according to their surface treatment with different powers of Er,Cr:YSGG laser at 2780 nm wavelength, 20 Hz frequency and 150 μs pulse duration in circumferential (C) or longitudinal (L) motion directions: Control group (no treatment), 0.5 W laser in longitudinally (L0.5), 1.0 W laser in longitudinally (L1), 1.5 W laser in longitudinally (L1.5), 0.5 W laser in circumferentially (C0.5), 1.0 W laser in circumferentially (C1) and 1.5 W laser in circumferentially (C1.5). After cementation, pull-out bond strength was measured in Newton (N). Each sample was inspected under a stereomicroscope at × 25 magnification to determine the mode of failure. Two samples of each group were inspected under a scanning electron microscope (SEM). Data were analyzed using two-way ANOVA and Tukey's test with significant level of 0.05. The pull-out bond strength of 0.5 W groups had significant differences with the control group (P = 0.009). The bond strength of 1.0 W and 1.5 W groups were not significantly different (P = 0.630) but were higher than the control and 0.5 W groups (P < 0.001). Motion direction of laser irradiation had no significant effect on the bond strength (P = 0.384). The interaction effect of power and motion direction of laser irradiation had no significant effect on the bond strength (P = 0.092).

CONCLUSION

Fiber posts treated with 0.5, 1.0 and 1.5 W Er,Cr:YSGG laser showed higher bond strength to dentin compared to posts with no surface treatment. However, the motion directions of laser irradiation had no significant effect on the bond strength. In order to minimize damage to post surface and achieving maximum bond strength, longitudinal surface treatment of posts with 1.0 W power of Er,Cr:YSGG laser is recommended.

The Effect of Diode and Er,Cr:YSGG Lasers on the Bond Strength of Fiber Posts

Background: Laser irradiation modifies the topography and composition of dentin surface aiming to increase the retention of bonded posts. Objective: To assess the effect of dentin irradiation with Er,Cr:YSGG or diode lasers on the bond strength of fiber posts using self-adhesive resin cement. Materials and methods: Sixty bovine root canals were root-canal treated, post spaces were prepared, and subsequently fiber posts were cemented. The samples were distributed according to the surface treatment: distilled water (control), Er,Cr:YSGG (1.5 W, 20 sec), or diode (1.5 W, 20 sec) lasers. Bond strengths were assessed by pull-out (n = 10) or push-out testing (n = 10). Pearson's correlation was calculated. Failure mode after testing and the depth of tags in the dentinal tubules were analyzed by confocal laser microscopy. Data were submitted to analysis of variance and Tukey's test. A p < 0.05 was considered significant. Results: In the push-out test, Er,Cr:YSGG laser had significantly different higher values (5.43 ± 0.10 MPa) compared to the control (4.79 ± 0.05 MPa). Diode laser values were not significantly different from the other groups (5.12 ± 0.27 MPa). In the pull-out test, there were no significant differences between Er,Cr:YSGG (6.86 ± 2.16 MPa) and diode (8.43 ± 1.77 MPa) lasers, and both had significant differences compared to the control (4.18 ± 1.29 MPa). No correlation was found. Adhesive failures were predominant in all groups, and no significant differences in tag penetration among the groups were found. Conclusions: The Er,Cr:YSGG laser increases the bond strength of resin cement and fiber post to dentin in both tests, compared to control group without laser treatment. Diode laser only enhanced bonding for pull-out test.

Mechanical properties and superficial characterization of a milled CAD-CAM glass fiber post

Computer-aided design and computer-aided manufacturing (CAD-CAM) technology may be used to produce custom intraradicular posts, but studies are lacking. The purpose of this in vitro study was to evaluate the flexural properties (strength and modulus), failure mode, superficial morphology, and roughness of two CAD-CAM glass fiber posts (milled at different angulations) compared with a commercially available prefabricated glass fiber post. Three groups were tested (n = 10): PF (control group)- prefabricated glass fiber post; C-Cd-diagonally milled post; and C-Cv-vertically milled post. A 3-dimensional virtual image was obtained from a prefabricated post, which guided the posterior milling of posts from a glass fiber disk (Trilor Blanks; Bioloren). Surface roughness and morphology were evaluated using confocal laser microscopy. Flexural strength and modulus were evaluated with the 3-point bend test. Data were submitted to one-way analysis of variance followed by the Student-Newman-Keuls post hoc test (α = 0.05). The fractured surfaces were evaluated with scanning electron microscopy. The superficial roughness was highest for PF and similar for the experimental groups. Morphological analysis shows different sizes and directions of the glass fibers along the post. The flexural strength was highest for PF (900.1 ± 30.4 > C-Cd - 357.2 ± 30.7 > C-Cv 101.8 ± 4.3 MPa) as was the flexural modulus (PF 19.3 ± 2.0 GPa > C-Cv 10.1 ± 1.9 GPa > C-Cd 7.8 ± 1.3 GPa). A CAD-CAM milled post seems a promising development, but processing requires optimizing, as the prefabricated post still shows better mechanical properties and superficial characteristics.

Evaluation of Push out Bond Strength of Fiber Post after Treating the Intra Radicular Post Space with Different Post Space Treatment Techniques: A Randomized Controlled In vitro Trial

Objective

The aim of this study was to evaluate the push out bond strength after treating the post space with different irrigation procedures.

Study Design

The study sample comprised of 60 recently extracted premolars. These teeth were placed in 5.25% sodium hypochlorite solution for 5 min and then washed under tap water. De-coronated samples were biomechanically prepared until F3 ProTaper and obturated using AH-Plus and 30# (6%) gutta-percha. The specimens were allowed to set for 24 h and then post space was prepared. The teeth were randomly assigned into three experimental groups based on the treatment technique: Group A - control, Group B - sodium hypochlorite and ethylene diamine tetra acetic acid (EDTA) and Group C - diode laser and EDTA. The samples were sectioned horizontally and push out bond strength was evaluated. The stereomicroscopic examination was done for evaluating the failure mode. One-way ANOVA variance followed by Tukey's post-hoc test was used for statistical analysis using SPSS software.

Results

Use of diode laser does not enhance the bond strength of fiber post.

Conclusion

Diode laser at a very low pulse can be used as an irrigant adjuvant to vaporize the cement residues. Using diode laser does not enhance the bond strength. EDTA as final irrigant increases the bond strength of fiber post.