Fiber Posts Research Articles

Push-Out Bond Strength of Glass Fiber Endodontic Posts with Different Diameters.

(1) Background: The retention of intraradicular posts is an important factor for the prognosis of endodontically treated teeth. The purpose of this study was to evaluate the push-out bond strength (PBS) of the posts relating to their diameter and region of the root. (2) Methods: A total of 40 premolar teeth (decoronated and root canal-filled) were divided into four groups (n = 10). After post-space preparation, different sizes (1.0, 1.2, 1.5, and 2.0 mm) of glass fiber posts were luted with resin cement into the root canals. After placement, 2 mm thick slices were cut from the roots according to their apical, middle, and coronal regions (n = 116). Push-out tests were carried out in a universal testing machine on each slice. A statistical evaluation of the data was applied. (3) Results: When comparing the diameter, the 2.0 mm posts had the highest PBS (111.99 ± 10.40 N), while the 1.0 mm posts had the lowest PBS (99.98 ± 8.05 N). Divided by the surface of the bonded area, the average PBS value was the highest for the 1.0 mm posts (18.20 ± 1.67 MPa) and the lowest for the 2.0 mm posts (12.08 ± 1.05 MPa). (4) Conclusions: Within the limitations of the study, when comparing the regions of the roots, no significant differences were found among the PBS values of the three regions (p = 0.219). When comparing the diameters, significant differences were shown between the PBS values of the four groups (p = 0.023 and p = 0.003, respectively).

Effect of Dentin Irrigants on Push-Out Bond Strength in Resin Cementation Protocols for Fiber Posts in Endodontically Treated Teeth: An In Vitro Study.

The aim of this study is to analyze the effects of different endodontic irrigants and adhesive systems on the resin bond strength of fiber post cementation. In total, 144 single-rooted, unrestored human teeth were endodontically treated and randomly divided into 12 groups according to four endodontic irrigants (distilled water as control; EDTA 17%; NaOCl 5%; chlorhexidine digluconate 2%) and three different adhesive/resin cement systems (etch-and-rinse: orthophosphoric acid, Parabond® A+B/Paracore®; self-etch: ParaBond® Non-Rinse Conditioner, Parabond® A+B/Paracore®; Universal: ClearfilTM Universal Bond/ClearfilTM DC Core Plus). Forty-eight hours after post cementation, ten teeth from each group were cross-sectioned into three discs (cervical, middle and apical regions). Thirty specimens of each group (n = 30) were submitted to a push-out test at a crosshead speed of 1 mm/min. The remaining two teeth of each group were sectioned in the same manner, and the resin-dentin interface was evaluated using scanning electron microscopy (SEM). The results were statistically analyzed with the ANOVA test and Tukey's test (p < 0,01). The adhesive protocols and post space region showed no significant effect on bond strength (p > 0.01). The combination of NaOCl 5% and ClearfilTM Universal Bond reduced the adhesive strength (p < 0.01). The NaOCl 5%, in relation to other irrigants, significantly decreased the push-out bond strength.

Evaluation of mechanical properties of anatomically customized fiber posts using E-glass short fiber-reinforced composite to restore weakened endodontically treated premolars

ObjectiveThis study was conducted to assess the influence of combining different forms of fiber-reinforced composites (FRC) on the mechanical behavior and bond strength of compromised endodontically treated teeth (ETT).Materials and methodsEighty extracted human premolar teeth were randomly divided into five experimental groups according to the type of intra-radicular restoration and the canal preparation design which was either non-flared (Group 1), flared (Groups 2–5), closed-apex (Groups 1,3,5) or open-apex (Groups 2,4). Standard prefabricated fiber posts were used as intra-radicular restoration for Groups 1–3 while Groups 4–5 were restored with anatomically customized relined fiber posts. After composite core fabrication, all samples were sent for an artificial aging process. Fracture resistance and push-out bond strength tests were then carried out through a universal testing machine followed by mode of failure analysis via a stereomicroscope and scanning electron microscope.ResultsPairwise Log-Rank comparisons revealed that the survival rate of Group 2 and Group 3 was significantly lower than all other groups after artificial aging. The highest fracture resistance value (1796 N) was recorded in Group 5 and was significantly higher than that of the other groups (p < 0.05), while Group 2 exhibited the lowest fracture resistance (758 N), which was significantly lower compared to the other groups. Group 5 and Group 4 demonstrated a significantly higher push-out bond strength, at all root thirds, than Group 3, Group 2, and Group 1 (p < 0.05). The most frequently observed failure mode in the tested groups occurred between the resin cement and radicular dentin.ConclusionThe use of short fiber-reinforced composite (SFRC) to reline the prefabricated FRC post has been proven to have superior fracture resistance with favorable failure patterns and increased push-out bond strength values compared to standard prefabricated FRC posts.

Intraradicular reinforcement of traumatized immature anterior teeth after MTA apexification.

This review article describes the methods and clinical recommendations for reinforcing traumatized anterior immature teeth with pulp necrosis treated with mineral trioxide aggregate (MTA) apexification. Traumatic injury can cause pulp necrosis and incomplete root formation in immature teeth. MTA apexification is the treatment of choice for necrotic immature teeth, particularly during the middle or late stages of root development. MTA apexification has a high success rate; however, failures due to cervical or root fractures occasionally occur. The risk of fracture is higher in immature teeth with thin root dentin, particularly those with external root resorption. Furthermore, the loading force from any parafunctional habit also increases fracture risk. Therefore, intra-radicular reinforcement may be necessary after MTA apexification. Invitro, intraradicular restoration with a resin composite/core build-up material or a prefabricated fiber post demonstrated better root reinforcement than root canal obturation materials (i.e., gutta-percha and sealer). However, the root-reinforcement effect of MTA orthograde filling in the entire root canal remains unclear. Invivo, the survival of fractured teeth with intraradicular restorations (resin composite/core build-up material or prefabricated fiber posts) is extremely high. Moreover, the survival of teeth with gutta-percha/sealer obturation or MTA orthograde filling and restoration with resin composite extending into the cervical third of the root canal approximately 1-2 mm below the cemento-enamel junction is acceptably high. Based on this evidence, the remaining tooth/root structure and loading force should be carefully examined when considering intra-radicular reinforcement of immature anterior teeth treated with MTA apexification.

Removal of fiber posts using conventional versus guided endodontics: a comparative study of dentin loss and complications.

To compare the efficacy of fiber post removal using conventional (CONV) versus guided endodontics (GE) in terms of dentin loss, residual resin material, procedural errors, and working time in vitro. Ninety human central incisors were root-filled and scanned by micro-computed tomography (CT), then restored with fiber posts and composite. Twenty-four sets of teeth with up to four human maxillary central incisors were fabricated and divided into three groups: conventional post removal by a general dentist (CG) or endodontology specialist (CS) and guided endodontics (GE) by a general dentist, yielding 30 teeth per operator and group. After treatment, the prepared access cavities were volumetrically assessed by micro-CT. Statistical significance was evaluated by one-way analysis of variance followed by post hoc comparisons with Tukey's HSD test and Pearson's chi-squared test for independence. Both CONV and GE resulted in dentin loss and residual resin material. CS resulted in more dentin loss and less residual resin material than CG and GE (p < .05). All groups had some deviations from the original root canal but no perforations. The shortest working time was observed in the GE group. Compared to the conventional freehand technique, GE resulted in significantly less radicular dentin loss, a few deviations but no perforations. Guided endodontics can improve the speed and safety of fiber post removal without root perforation.

Fracture strength of fiber post with polyetheretherketone post: An In vitro comparative study

Abstract Aim: To assess and compare the fracture strength of polyetheretherketone (PEEK) post materials with fiber posts on endodontically treated maxillary central incisors. Materials and Methods: In this in vitro comparative study, two dental post materials were evaluated: fiber-reinforced post and PEEK post. Simple random sampling was done and 30 specimens were fabricated using extracted, decoronated, and endodontically treated maxillary central incisors (n = 15 for each group). Post-space preparation was done 5 mm short of the apex and restored with prefabricated fiber post (n = 15) and customized PEEK post (n = 15). Samples were mounted in a cold cure acrylic cylindrical block, at 45° angulation for testing the fracture strength using a universal testing machine. The data were analyzed and compared statistically, using an independent t test. Results: Mean fracture strength of the PEEK post was 65.79 kg and the fiber post was 59.32 kg with no statistically significant difference in the fracture strength between the two groups. Conclusion: Within the limitations of the study, it can be concluded that the PEEK post has similar mechanical properties to the fiber post and could be considered as an alternative to the fiber post having the advantages of being custom-made requiring conservative canal preparation with minimal dentin removal.

The impact of methylene blue photosensitizer, aPDT and a calcium hydroxide-based paste on the physicochemical and mechanical characteristics of root canal dentin and the bonding interface of fiberglass posts

PurposeTo investigate the influence of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and calcium hydroxide (CH) medication on the mechanical characteristics, degree of conversion (DC), quantification, and volume of gaps at the adhesive interface of glass fiber posts (GFPs) luted to distinct thirds of root canal dentin. Additionally, the microhardness (MH), elastic modulus (Eit), morphology, and chemical structure of the intraradicular dentin were assessed. Materials and methods6 experimental groups were formed by sorting 102 bovine incisors. Canals receiving deionized water irrigation as a negative control; canals receiving deionized water irrigation and filled with CH as a positive control; groups treated with CH + MB at 50 and 100 mg/L without irradiation; and groups treated with CH + MB at 50 and 100 mg/L irradiated by red laser for 60 s (660 nm; 100 mW; 6.5 J; 72 J/cm2). MH, Eit, and DC properties were evaluated for both the resin cement layer and root dentin substrate (n = 8). Volume and quantification of gaps at the bonding interface (n = 6), and dentin morphology and chemical content were investigated (n = 3). Data were analyzed using a repeated-measures 2-way ANOVA followed by Tukey post hoc analysis (α = 0.05). ResultsThe distinct intraradicular thirds and treatment with MB-mediated aPDT, whether activated or not, in combination with CH, had a significant impact on the mechanical characteristics of the root dentin. This effect was also observed in the MH, Eit, DC, quantification, and volume of gaps at the luting interface (P < .05). In general, a higher concentration of MB, whether activated by a red laser or not, led to lower values in the mechanical properties of the root dentin, as well as in MH, Eit, and DC at the adhesive interface (P < .05). Additionally, these groups exhibited higher values for quantification and volume of gaps at the luting substrate (P < .05). Scanning electron micrographs and energy dispersive X-ray spectra showed qualitative similarity among all groups, except for the negative experimental control group. ConclusionsMB-mediated aPDT at 50 mg/L, in combination with CH, demonstrated favorable physico-chemical and mechanical characteristics in intraradicular dentin, along with satisfactory mechanical features and the adhesive interface integrity for GFPs at all intraradicular depths. Clinical significanceMB-mediated aPDT at a concentration of 50 mg/L combined to CH medication represents a suitable choice for photosensitization in the context of intracanal disinfection following the biomechanical procedure and prior to luting of intraradicular restorations.

Evaluation of the Mechanical Properties of 3D-Printed Post and Core Systems.

To evaluate and compare the fracture resistance and elastic modulus of 3D-printed post and core systems and fiber posts and composite cores. Endodontic treatment was performed on 30 mandibular premolars, and post space preparation was performed. The teeth were then randomly divided into two groups (n = 15 per group): the 3D-printed (3DP) group and the fiber post and composite core (FPC) group. In the FPC group, fiber posts (Cytec Blanco 43.604, Hahnenkratt) were bonded with resin cement (RelyX U200, 3M), and the composite core dimension was standardized with a silicone index. In the 3DP group, the impression of the post space for each specimen was taken with pattern resin (Pattern Resin, GC America), and the coronal core was produced with the same silicone index. The impressions of the posts and cores were scanned, and then the custom post and core structures were fabricated from permanent crown resin material (Permanent Crown Resin, Formlabs) with a 3D printer (Form3B, Formlabs). Specimens were subjected to load tests with a universal testing machine (M500-25AT, Testometric). After fracture occurred, the fracture force and elastic modulus were calculated. The data were analyzed by independent sample t test (α = .05) Results: There was no statistically significant difference between the two groups in terms of peak fracture force (P = .626) and elastic modulus (P = .125), and no catastrophic root fractures were observed in either group. The fracture resistance of endodontically treated teeth was not significantly influenced by the post material. 3D-printed, custom-made resin posts were as effective as fiber glass posts with regard to fracture resistance.

Removal Efficiency and Effectiveness of Four Different Fiber Posts Using Five Different Drill Systems in Multirooted Teeth.

In comparing the effectiveness and efficiency of different types of post removal systems in removing different types of fiber posts (FPs), this study aims to shed light on the success of removal by currently available drill systems. A total of 200 maxillary first molars, were root canal treated and prepared to receive posts. The molars were divided into four groups corresponding to four different FPs: Group RX, Radix FP; Group RF, Reforpost Glass Fiber; Group HI; Hi-Rem Endodontic Post; and Group DT, D.T. Light-Post Illusion X-RO. Fiber posts were done with luting by Gradia Core (GC America, Inc.). Groups were again divided into five subgroups corresponding to the technique by which the FP was removed into as follows: Subgroup P, PD-25-1.1 Drill; subgroup G, GC FP Drill; subgroup E, EasyPost Precision Drill; subgroup R, Reaccess Carbide Double Taper Kit; and subgroup H; H-Endodontic Drill. After posts were removed, effectiveness and efficiency were documented. Data were tabulated and statistically analyzed. Strong significant differences regarding efficiency among groups (FP type) and subgroups (drills used) (p = 0.00) were shown by the one-way analysis of variance (ANOVA) test. Subgroup DT-G scored the longest mean removal time (20.9 minutes) while Subgroup RX-R scored the shortest mean removal time (1.4 minutes) Regarding effectiveness, strong significant differences among groups (p = 0.00) and subgroups (p = 0.00) were shown by one-way ANOVA. Subgroup RF-G scored the highest scale (5.2) whereas subgroup HI-R scored the lowest mean scale (1.2). The difference was strongly significant between tested post-removal kits and between tested FPs. Re-access Carbide Double Taper Kit performed superiorly in both effectiveness and efficiency, followed by PD-25-1.1 Drill. Hi-Rem post showed the best retrieving results among other FPs. Knowing the best technique and tools for post removal could spare the practitioner any unwanted complications during post removal. How to cite this article: Sayed M, Alahmad AM, Alhajji KS, et al. Removal Efficiency and Effectiveness of Four Different Fiber Posts Using Five Different Drill Systems in Multirooted Teeth. J Contemp Dent Pract 2024;25(1):72-78.

Evaluation of the Fracture Resistance of Different Designs of All-Resin Post and Core Systems: An In Vitro Study.

Introduction There is a growing demand for post and core systems that offer both ease of use and efficiency. Recently introduced dual-cure build-up and post cement materials exhibit properties similar to dentin. The objective of this laboratory experiment is to compare the fracture resistance among three distinct post and core systems and identify the locations of failures within each group. Material and methods This in vitro experimental study involved 30 epoxy resin-based blocks (Endo Training Bloc J, Dentsply Sirona, Ballaigues, Switzerland) divided into three groups: The first group was a post space preparation and restoration with a fiber post (RelyX™ Fiber Post, 3M ESPE, Saint Paul, Minnesota, United States) 1.6 mm in diameter and 10 mm in length (Group A) where core build-up and cementation were performed using a dual-cure build-up and cement for endodontic post resin material (Core X Flow, Dentsply DeTrey, Konstanz, Germany). The second group was a post space preparation and restoration using a dual-cure build-up and cement for endodontic post resin material, 10 mm in length filled with resin but without fiber post placement (Group B). The third group was where post space and core were filled and restored with a dual-cure build-up and cement for endodontic post resin material, 5 mm in length and without fiber post placement (Group C). Subsequently, samples were mounted and tested using a universal testing machine (Instron, Canton, Massachusetts, United States), and the fracture site was located. Results Significant differences were identified among the three groups, indicating the impact of both post length and type on fracture resistance (p-value <0.05). Group B exhibited the highest mean compressive strength resistance and maximum load at 899.3330 (N), followed by Group C at 848.9690 (N) and Group A at 751.9620 (N). The predominant failures in the samples were core fractures or debonding of the core material. Conclusion All-resin posts demonstrated high fracture resistance, unlike fiber posts which displayed inferior fracture resistance.

Assessment of Various Post Systems’ Fracture Resistance after Endodontic Treatment

ABSTRACT Objectives: The study’s objective is to evaluate the fracture resistance of a tooth that has had endodontic treatment and has been rebuilt using various post and core systems. Materials and Methods: Thirty-six extracted premolar teeth of similar sizes were picked, and at random, they were separated into three groups: group A received stainless-steel posts, group B received zirconia fiber posts, and group C received glass fiber posts. Dual-cured resin cement was used to cement each post. The acrylic resin blocks have samples imbedded in them. Additionally, fracture loads were measured while a compressive force was given to the tooth at a crosshead speed of 1 mm/minute. The one-way analysis of variance F-test and post hoc Tukey’s test were then used to analyze the results. Results: When the mean values and standard deviation were compared, it was found that glass fiber posts had the highest fracture resistance, followed by posts made of zirconia fiber, while stainless-steel posts had the lowest fracture resistance Conclusion: When compared to zirconia posts and stainless-steel posts, glass fiber posts had the highest level of fracture resistance.

Stress Distribution on Maxillary Canines Following Restoration With Different Dimensions of Metal and Fiber Posts: A Finite Element Study.

Introduction In recent times, finite element analysis (FEA) in the field of dentistry has been employed to assess the mechanical properties of biological materials and tissues, which are difficult to quantify directly within a living organism. Only a limited number of studies have examined the impact of post diameter and length on how stress is dispersed in a maxillary canine tooth. Hence, this in vitro investigation was conducted to analyze the distribution of stress in a maxillary canine tooth that was replaced using metal and fiber posts with different diameters (1.5 mm and 1.8 mm) and lengths (11 mm and 15 mm), applying FEA. Materials and methods A FEA study was performed and all models were grouped as follows: Models 1 and 5 were made of titanium (Ti) and glass fiber posts, respectively, with a diameter of 1.5 mm and a length of 15 mm with composite core and all-ceramic crown; Models 2 and 6 were made of Ti and glass fiber posts, respectively, with a diameter of 1.5 mm and a length of 11 mm with composite core and all-ceramic crown; Models 3 and 7 were made of Ti and glass fiber posts, respectively, with a diameter of 1.8 mm and a length of 15 mm with composite core and all-ceramic crown; and Models 4 and 8 were made of Ti and glass fiber posts, respectively, with a diameter of 1.8 mm and a length of 11 mm with composite core and all-ceramic crown. A force of 200 N was exerted on the ceramic crown at an angulation of 45° to the longitudinal axis of the tooth on the palatal surface above the cingulum. The failure was determined by the correlation between a larger von Mises stress estimate and an increased likelihood of failure. The resulting stresses were then contrasted with the highest possible tensile strength of the material. Results The study demonstrated that fiber posts with a diameter of 1.8 mm and an average length of 11 mm exhibited reduced stress levels in comparison to Ti posts. The largest stresses were seen at the cervical region of the tooth, regardless of the materials employed. There was no discernible alteration in stress when the length and diameter of the post were modified. The highest stress in the composite core was measured in Ti posts measuring 1.5 mm in diameter and 15 mm in length. The highest level of stress on dentin was noted in cases where a fiber post was used, as opposed to cases where a Ti post was used. The measured stress within the fiber post was insignificant. However, the pressures imparted to the dentin were greater and more uniformly distributed in comparison to the Ti post cases. Conclusion It is suggested that a composite resin core be used along with a fiber post that is larger in diameter and smaller in length, within clinical bounds, in order to lessen stress in the radicular tooth, despite the substantial coronal defect. Further clinical trials are required to assess the survival rate of these specific measurements, dimensions, and biomaterials.

Radiographic Assessment of 121 Glass Fiber Post Procedures in 32 Patients Aged 21-60 Years Performed by 6th-Year Dental Students During the 2022-2023 Academic Year at the College of Dentistry, Jazan University, Saudi Arabia.

BACKGROUND The restoration of endodontically treated teeth (ETT) and severely damaged teeth has been a concern of clinicians. Glass Fiber Post (GFPs) combine the strength of carbon fiber posts with the esthetic appearance of glass to resemble natural dentin during dental restoration procedures. This radiographical study assessed the GFP carried out by students enrolled in the Clinical Comprehensive Course at the College of Dentistry, Jazan University. MATERIAL AND METHODS A total of 32 patients treated by 18 6th-year dental students with 121 GFPs were assessed in this cross-sectional radiographic study. The assessment covered tooth type, arch, post-to-root width, length of post in relation to the crown and root lengths, amount of remaining gutta percha (GP), and gap between GP and post. Data were analyzed using SPSS, and associations between variables were determined using the chi-square test. RESULTS Maxillary teeth were the most frequently restored with posts (88.4%) with most being (58.7%) anterior teeth, and 50.4% of posts had widths that were one-third that of the root. The percentage of posts was twice (71.1%) or equal to (26.4%) the crown length, whereas two-thirds of the tested GFPs were >5 mm of the remaining GP. Significant differences were observed in location and position of teeth with post width, post length in relation to crown or root length, and amount of remaining GP, with P values of 0.018, 0.000, and 0.001, respectively. CONCLUSIONS The assessed radiographs revealed that the performance of sixth year students in accomplishment GFP radiographically was satisfactory and within the values recommended in the literature.

Restoring an Extremely Destructed Tooth with Flared Root Canal Walls: A Case Report.

Reconstructing severely damaged teeth has always presented a challenge when the remaining crown structure is limited, often requiring retention from the root canal using intracanal posts. However, the real challenge is when the root canal walls are also weak, and there is a high risk of vertical root fracture due to the wedging forces of a rigid post. This case report presents a tooth with extremely flared (0.3mm) root canal walls, successfully restored with a newly introduced polymer made of polyether ether ketone (PEEK), with one-year follow-up. Due to its close elastic modulus to dentin, capacity to bond effectively to tooth structure, shock-absorbing properties, and thereby facilitating favorable stress distribution, utilizing this material for an intracanal post has the potential to mitigate the risk of fractures often associated with cast metal posts. It combines the good fitness of cast posts with the low modulus of elasticity and optical properties of prefabricated fiber posts.

Evaluation the Fracture Resistance of Endodontically Treated Teeth Restored With Different Post and Core Materials

Widespread use of prefabricated post that provides retention and support for core and the final crown has caused manufacturers to produce different types of post materials. The aim of this study was to evaluative the fracture resistance of two types of post materials and two types of core material. Forty extracted human mandibular premolar were selected. After root canal preparation and obturation with gutta percha the roots were divided into two groups according to the type of post material, group F restored with fiber post and group T restored with titanium post then each group was subdivided into two subgroup according to the type of core materials which include composite and amalgam restorative materials. Then all the teeth were subjected to compressive load at 130o angle from the horizontal plan at a 5mm/min crosshead speed until fracture. Results showed that there was significant different between groups in term of fracture loads (P= 0.0156). Also the fracture loads of teeth restored with titanium post and composite core has highest mean fracture load (812N), whereas teeth restored with fiber post and amalgam core demonstrated the lowest mean fracture load (643.1N). The study concluded that the teeth restored with metal titanium post were more fracture resistant than those restored with fiber posts. But the combination of a fiber post and composite core has the favorable mode of fracture that considered reparable, while considered unfavorable when restored with titanium post.

Stress analysis of horizontal mid-root fracture managed with different intraradicular fixation protocols: A 3D-finite element study.

The current study evaluated the stress distribution in a maxillary central incisor with mid-root fracture after splinting with different intra-radicular posts using 3D-finite element analysis (FEA).Five 3D-FEA models were constructed. Model 1 was an intact tooth with no fracture, Model 2: A tooth with a horizontal mid-root fracture, with no treatment. Model 3: Same as model 2, and intraradicular splinting using fiber post. Model 4: Same as model 2 and intra-radicular splinting using Protaper Gold file F3. Model 5: Same as model 2, and with intraradicular splinting with Ribbond. The FEA of all models was done to obtain the maximum Von-Mises stress in the root canal space, the dentin, the periodontal ligament, and the bone. The highest Von Mises stresses for the root canal space and the dentin were found in Model 3, followed by models 4, 5, and 2, and least in Model 1. The Von Mises stress of the periodontal ligament was the least in model 1. The Von Mises stress of bone was higher in all experimental models than in the baseline model. The results suggest that in cases where intra-radicular splinting is indicated, fiber posts and Ribbond are better alternatives to endodontic files due to the lower stresses exerted.

Effect of a 10-Methacryloyloxydecyl Dihydrogen Phosphate- treated Bioceramic Sealer on the Bond Strength of an Endodontic Fiber Post: Multilayer Composite Disk Models and Ultra-highspeed Imaging Analysis

Multiple materials are found in the root canal after fiber-post cementation. The layer of a bioceramic-based (BC) sealer may affect the bond strength (σBS) of the fiber post in the root canal. The purpose of this study was to employ multilayer compos-ite-disk models in diametral compression to investigate whether the bond strength between a fiber post and root dentin can be in-creased by the application of a primer on the BC sealer. The multilayers of materials in the root canal required 3D finite-element (FE) stress analyses (FEA) to pro-vide precise σBS values. First, BC sealer was characterized using x-ray powder diffraction (XRD) to determine when the sealer com-pletely set and the types of crystals formed to select which primer to apply to the sealer. We selected a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-based primer to treat the BC sealer before post cementation. Ultra-highspeed (UHS) imaging was utilized to analyze the crack initiation interface. The obtained failure force was used in FE analysis to calculate σBS. UHS imaging validated the fracture interface at the post-dentin junction as FEA simulations predicted. σBS values of the fiber posts placed with various material combinations in the root canal were 21.1 ± 3.4 (only cement/ post), 22.2 ± 3.4 (BC sealer/cement/post) and 28.6 ± 4.3 MPa (10-MDP primer treated BC sealer/cement/post). The 10-MDP-treated BC sealer exhibited the highest σBS (p < 0.05). The multilayer composite disk model proved reliable with diametral compression testing. The presence of BC sealer in the root canal does not reduce σBS of the fiber post. Conditioning the BC sealer layer with 10-MDP primer before fiber-post cemen-tation increases σBS.

Mechanical behavior of endodontically treated teeth: A three-dimensional finite element analysis using displacement vector.

This study aimed to analyze the effects of core materials, remaining tooth structures, and interfacial bonding on stress distribution in endodontically treated teeth using finite element analysis (FEA). Three-dimensional FEA was conducted using a reverse engineering technique based on maxillary premolars scanned by micro-computed tomography. Six models were generated with or without ferrules and with one of the following three abutment systems: metal core, resin core, or resin core with fiber posts. In each model, bonding and debonding were assumed in the dentin and surrounding structures: bonded and debonded models. The maximum principal stress values were recorded, and stress distribution of the entire restored teeth and dentin was generated. Furthermore, the distribution of the displacement vector of the debonded models was generated. In comparing the bonded and debonded models, the debonded models showed larger values for tensile stresses than those in bonded models for all abutment models. The models without ferrules rotated around the center of the abutment, whereas those with ferrules did not show remarkable displacement in the analysis. FEA assuming fracture of adhesive interface proved to be an effective method to clarify the significance of ferrules. It prevents stress concentration in dentin by reducing the rotation of the abutment, even when the adhesive fails.

A microcomputed tomography analysis of adaptation in premolars with flared root canals restored with different digitally custom fabricated post materials

Statement of problemPreserving and strengthening the remaining tooth structure of compromised flared root canals after endodontic treatment is challenging. PurposeThe purpose of this in vitro study was to compare the adaptation of milled polymer- infiltrated ceramic, fiber-reinforced composite resin, and high-performance semicrystalline thermoplastic resin posts as used to restore mandibular premolars with flared root canals. Material and methodsForty sound mandibular premolars were randomly divided into 4 groups: custom Vita Enamic (CV), custom fiber-reinforced composite resin (CF), custom polyetherketoneketone (CP), and prefabricated fiber (RF) posts. After endodontic treatment, each tooth was sectioned 1.5 mm occlusal to the cementoenamel junction. Then, the post space was prepared and flared, except the RF group, to a depth of 9 mm. The post space in RF group was prepared with a post drill. For the CV, CF, and CP groups, the posts were milled, finished, and cemented to their corresponding teeth. Each tooth was scanned using a microcomputed tomography device, and the reconstructed images were analyzed in mesiodistal, buccolingual, and horizontal planes. The cement thickness, cement volume, and volume of voids were measured. The data were analyzed using 3-way ANOVA (cement thickness) and 2-way ANOVA (cement volume and voids volume) tests followed by the post hoc Tukey test (α=.05). ResultsThe 3-way ANOVA test revealed a significant interaction (P<.001) between material type, section, and surface on the cement thickness. The mean cement thickness in the RF group was significantly higher than in the CV group (P=.001) and CF group (P=.005). The least mean cement thickness was at the apical section followed by the cervical and middle sections. Regarding cement volume, the 2-way ANOVA test showed statistically significant interaction between material type and section. The mean cement volume in the RF group was significantly lower than in the CV group (P=.001), CF group (P=.001), and CP group (P=.001). The highest mean cement volume was in the cervical section followed by the middle and apical sections. The 2-way ANOVA test showed statistically significant interaction (P<.001) between material type and section on the volume of voids. Significant differences were found between the mean volume of voids at the cervical and middle sections (P=.001) and the cervical and apical sections (P=.002). ConclusionsCompared with prefabricated fiber posts, digitally fabricated polymer-infiltrated ceramic and fiber-reinforced composite resin posts had a thinner cement layer with minimal thickness at the apical section. The digitally fabricated posts had higher cement volume, especially at the cervical section, than prefabricated fiber posts. High volumes of voids were related to the cervical section of all tested posts.

Post retention strength of apical and conventional coating obturation methods using bioceramic sealer: a laboratory investigation

BackgroundOnce bioceramic sealer (BCS) enters the dentinal tubules, it cannot be reliably removed. BCS-occupied dentinal tubules reduce fibre post retention strength. Coating gutta-percha with BCS only on the apical portion may improve post retention strength due to increased retention strength between the dentin and resin cement interface. The aim of the study was to test this hypothesis.MethodsRoot canals of 27 extracted human mandibular premolars were instrumented and randomly assigned to three obturation methods: conventional coating (CC), non-coating (NC), and apical coating (AC). The root canals were obturated with gutta-percha to 4 mm from the working length under an operating microscope. After the BCS was completely set, post spaces were prepared, and quartz fibre posts were cemented. The apical 4.5 mm of the roots were removed. Two samples were prepared at the apical, middle, and coronal root levels (one for scanning electron microscope (SEM) study and another for the push out bond strength (PBS) test). After the PBS test, the samples were examined with a stereo microscope to determine the failure mode: dentine-cement (DC), post-cement (PC) and mixed. The PBS data were analysed by One way ANOVA for the specific obturation method effects. Repeated ANOVA was used for the specific effects of the root levels on PBS in different obturation methods.ResultsAt all three root levels, more continuous hybrid layers and denser resin tags were found in the NC and AC than the CC group. The AC and NC groups’ PBS was significantly higher than the CC group at the apical 1/3 (p = 0.002 and p = 0.001) and coronal 1/3 (p = 0.016 and p = 0.041). The PBS in the CC group at the middle 1/3 was significantly higher than the apical 1/3 (p = 0.022). DC failure mode was most commonly found in the CC group, while PC failure mode was found most frequently in the NC and AC groups.ConclusionsThe apical coating obturation method significantly increased PBS over the conventional coating method, potentially reducing fiber post dislodgement. However, this study was only preliminary. Clinical studies are required to confirm the results.