Customized Fiber Post Improves the Bond Strength and Dentinal Penetrability of Resin Cementation System to Root Dentin

SUMMARY Objective: This study aimed to evaluate the effect of fiber post customization on the bond strength (24 hours and 6 months), resin cement thickness, and dentinal penetrability of Adper Scotchbond Multi-Purpose – RelyX ARC (AS-RA), RelyX U200 (R2), and Scotchbond Universal – RelyX Ultimate (SU-RU) cementation systems to root dentin from the cervical-, middle-, and apical-thirds of the post space. Methods: One hundred twenty bovine incisors were endodontically treated. After post space preparation, the roots were divided into six groups, according to the luting protocols (AS–RA, R2, SU– RU) and the type of fiber post [noncustomized post (NC) and customized post (C)]. Customization procedures were peformed using a resin composite (Z350 XT). 24 hours (n=60) or 6 months later (n=60), specimens from the cervical-, middle-, and apical-thirds of the post space were submitted to cementation system thickness measurement, bond strength evaluation, and dentinal penetrability analysis with Confocal Laser Scanning Microscopy (CLSM). Failure mode was classified as adhesive, cohesive, or mixed. Data were submitted to ANOVA and Tukey tests (α=0.05). Results: Cementation protocols with customized fiber posts presented the lowest cementation system thickness, regardless of the cementation system or post space-third (p<0.05), and the highest bond strength values (p<0.05), regardless of the third space (p>0.05), for both periods (24 hours or 6 months). The comparison of push-out bond strength values between 24 hours and 6 months showed a reduction in all groups for the cervical-third (p<0.05). For the middle-third, only noncustomized groups showed reduction (p<0.05). For the apical-third, no reduction was observed (p>0.05). Conclusions: Anatomical customization favored both the bond strength of cements to dentin and the dentinal penetrability, but with lower cementation system thickness, regardless of cement composition and adhesive strategy.

Use of fiberglass CAD-CAM post-and-core for rapid orthodontic extrusion of anterior tooth – Case Report

This report describes the restoration of an anterior fractured tooth with a fiberglass CAD-CAM post-and-core followed by rapid orthodontic extrusion. The post space was prepared, the post-and-core was luted and a interim crown was luted to allow the tooth extrusion through the use of orthodontic buttons and elastic rubber bands. A lithium disilicate glass-ceramic crown was luted and the case was followed up after 6 and 12 months.

Use of Rose Bengal, Methylene blue and Curcumin Photosensitizers activated using light emitting diode on post space disinfection bonded to fiber post: An assessment of extrusion bond strength

Objectives: To evaluate the effect of Rose Bengal (RB), methylene blue (MB) and curcumin used as a canal disinfectant on the extrusion bond strength (EBS) of FRCP (fiber reinforced composite resin) with canal dentin. Methods: The present invitro study was completed in 90 days approved by Riyadh Elm University. Forty premolars were extracted disinfected and decoronated. Mechanochemical preparation was done of canal space using 10k file widening canals sequentially with a 25K file with constant saline irrigation. Canal was dried condensed with gutta percha and sealer. Post space was prepared using peso reamer. Based on canal disinfection samples were divided into four groups. Group-1 MBP+17%EDTA, Group-2 RBP +17% EDTA, Group-3 Curcumin+17% EDTA and Group-4 5.25% NaOCl +17% EDTA. Following disinfection, the canal space of all specimens was washed with 17% EDTA for 120 sec. Post was cemented in canal space and cured. Specimens were placed on Universal testing machine (UTM) for EBS. The type of bond failure was evaluated using stereomicroscope. ANOVA and Tukey multiple comparison test was used to compare means. Results: Cervical third of Group-3 in which samples were disinfected with CP+17% EDTA displayed the maximum EBS (8.69±1.32 MPa). Whereas, the lowest EBS (3.30±0.54 MPa) was exhibited by the apical third of Group-4, where 5.25% NaOCl +17% EDTA was used as a canal disinfectant. The intragroup comparison demonstrated a declining trend of EBS from cervical to apical third in all investigated groups. Conclusion: Root canal dentin treated with different PS (MBP, CP, and RBP) demonstrated better EBS than the conventional disinfecting regime (NaOCl +17% EDTA). CP and RBP displayed better EBS than MBP. doi: https://doi.org/10.12669/pjms.38.1.4780 How to cite this:Niazi FH, Qamar Z, Noushad M, Khaled Bin Muhareb A. Use of Rose Bengal, Methylene blue and Curcumin Photosensitizers activated using light emitting diode on post space disinfection bonded to fiber post: An assessment of extrusion bond strength. Pak J Med Sci. 2022;38(1):---------. doi: https://doi.org/10.12669/pjms.38.1.4780 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bone loss recovery in mice following microgravity with concurrent bone-compartment-specific osteocyte characteristics

Space missions provide the opportunity to investigate the influence of gravity on the dynamic remodelling processes in bone. Mice were examined following space flight and subsequent recovery to determine the effects on bone compartment-specific microstructure and composition. The resulting bone loss following microgravity recovered only in trabecular bone, while in cortical bone the tissue mineral density was restored after only one week on Earth. Detection of TRAP-positive bone surface cells in the trabecular compartment indicated increased resorption following space flight. In cortical bone, a persistent reduced viability of osteocytes suggested an impaired sensitivity to mechanical stresses. A compartment-dependent structural recovery from microgravity-induced bone loss was shown, with a direct osteocytic contribution to persistent low bone volume in the cortical region even after a recovery period. Trabecular recovery was not accompanied by changes in osteocyte characteristics. These post-space-flight findings will contribute to the understanding of compositional changes that compromise bone quality caused by unloading, immobilisation, or disuse.

Efficacy of different instruments for the mechanical removal of the smear layer in immediate post preparations: a comparative study

Adhesively cemented fiber-reinforced composite posts are commonly used to reconstruct endodontically treated teeth. Adhesion to intraradicular dentin is complex, and close contact between the resin cements and the dentin is essential. The removal of the smear layer following post space preparation (secondary smear layer) can improve this integration. Different mechanical systems have been used to activate the irrigant inside the root canal. The purpose of this study was to compare, ex-vivo, the removal of the smear layer from the walls of the immediate post space preparation by the action of three mechanized instruments. Forty premolar specimens with a single root canal were selected, endodontically treated, and shaped for glass fiber post cementation with Peeso reamer #1 (Dentsply Sirona, Switzerland) and Macrolock finishing drill #3 (RTD, France). The specimens were randomly divided into 4 groups (n=10): Group C (control); Group PUI (passive ultrasonic irrigation); Group CEP (Rotoprox brush, Hager Werken, Germany) and Group XP (XP-endo Finisher, FKG Dentaire, Switzerland). Post space surfaces were cleaned with 3mL of distilled water; each specimen root split longitudinally to expose the root canals, and prepared for examination in a scanning electron microscope at magnification 350X. The results were analyzed using the Kruskal-Wallis and Friedman tests (p>0.05). RESULTS: Statistically significant differences (p <0.05) were found between Groups C and XP in all three root regions, but not between Groups C, CEP and PIU. Of these, Group CEP showed a better trend in the results of the coronary and middle thirds, without significant difference with Group XP. Although it was difficult to achieve a clean dentin surface after preparation for the fiberglass post, the XP-endo Finisher was the most efficient in removing secondary smear layer, followed by the Rotoprox conical brush.

Post-Space Treatment Influences the Bond Strength In Endodontically Treated Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies

SUMMARY Objectives: This systematic review of in vitro studies investigated the influence of the post-space treatment used to remove the smear layer on the bond strength of the post to root canal dentin. Methods and Materials: In vitro studies included in this study were identified from PubMed/MEDLINE, Lilacs, and Scopus databases up until March 2019, without limits on publication year or language. Two reviewers independently selected the studies based on the inclusion and exclusion criteria, extracted the data, and evaluated the risk of bias of all studies. A random effects model was used for pairwise meta-analyses (control vs. post-space preparation groups) at a significance level of p&lt;0.05. Results: Of the 2,832 potentially eligible studies, 453 studies were selected for full-text analysis, and 75 were included in this systematic review. Only one study was considered to have a low risk of bias. Overall, post-space treatment significantly improves the bond strength to root canal dentin (p&lt;0.00001). Conclusion: Post-space treatment has a positive influence on the bond strength of the post to root canal dentin. In this review, the post-space treatments that improve the adhesive resistance of the post were ethanol, sodium hypochlorite, and ethylene diamine tetra-acetic acid (NaOCl + EDTA), NaOCl + EDTA + ultrasound, erbium-doped yttrium aluminium garnet laser (Er:YAG laser), neodymium-doped yttrium aluminium garnet laser (Nd:YAG laser), and diode laser.