UNASSIGNED: The aim of this study was to compare the fracture strength and fracture modes of post-cores produced with CAD-CAM from modified polyetheretherketone (PEEK) materials with other custom-produced post-cores.
UNASSIGNED: Sixty human mandibular first premolars with equal root sizes were used. The teeth were divided into six groups (n = 10), and root canal treatment was performed. The teeth were separated from the roots over 2 mm from the cemento-enamel junction. As a result of the decoronation process, a 1 mm wide shoulder line was obtained for all teeth. For the fracture strength test, 10 mm deep post spaces were created on the teeth with a 1.6 mm diameter driller. Post-core groups consisted: everStick® glass fiber post-core (Group GF), zirconia post-core (Group Z), metal (Cr-Co) post-core (Group M), PEEK post-core without filler (Group UP), PEEK post-core with 20% TiO2 Filler (Group TP), and post-core with 20% ceramic filler (Group CP). Following the application of posts to post spaces, copings were created and cemented on the samples. With the universal tester, a force was applied to the long axis of the tooth with a slope of 135°. The mean fracture strength (N) between the groups was statistically evaluated using one-way ANOVA, and pairwise mean differences were detected using post hoc Tukey\'s HSD test among the groups.
UNASSIGNED: According to the results of the statistical analysis, a significant difference was found between the groups in terms of mean fracture resistance (p < 0.05). Group Z (409.34 ± 45.72) was significantly higher than Group UP (286.64 ± 37.79), CP (298.00 ± 72.30), and TP (280.08 ± 67.83). Group M (376.17 ± 73.28) was significantly higher than Group UP (286.64 ± 37.79) and Group TP (280.08 ± 67.83). There were no statistically significant differences between the means of the other groups (p > 0.05). Among all the groups, Group Z exhibited a higher prevalence of repairable failure modes, while the rest of the groups predominantly experienced irreparable failure modes.
UNASSIGNED: In our study, zirconia and metal post-core samples showed higher average fracture strength values than PEEK post-cores groups. Repairable failure modes were more common in the zirconia post-cores, whereas the opposite was observed in the other groups. Further experimental and clinical trial studies are needed before PEEK materials can be used as post materials in the clinic.

OBJECTIVE: This study was designed to investigate the effect of post space conditioning with different solutions on the bond strength of glass FRC posts and evaluate the mode of resin failure.
METHODS: Sixty extracted human single rooted teeth were root filled using a resin sealer and suitable gutta-percha cones. Post spaces were prepared, and the teeth randomly allocated into 5 groups according to their irrigation regimens which included the following solutions: 17 % EDTA, 2 % CHX, 3 % NaOCl, 10 % ascorbic acid and QMix solutions. Post spaces were irrigated with 5 ml of the solution for 15 s and subsequently washed with distilled water and dried with paper points. Glass FRC posts were cemented into their spaces using a self-adhesive resin cement. The specimens were mounted in plexiglass molds using autopolymerizing acrylic resin. A universal testing machine was used to measure post retention at a crosshead speed of 2 mm/min. The results were analyzed by one-way ANOVA followed by Tukey HSD test (α = 0.05). Dislodged posts and post spaces were examined microscopically to evaluate retention failure.
RESULTS: The Ascorbic acid group exhibited the highest mean retentive strength value at 229 N, followed by QMix at 198 N, NaOCl at 186 N, CHX at 170 N, and EDTA at 124 N. The mean value of the ascorbic acid group was significantly higher than EDTA group, p = 0.012. The failure category was primarily mixed.
CONCLUSIONS: Rinsing post spaces with ascorbic acid exhibited significantly superior bond strength. The failure mode was mixed.
CONCLUSIONS: Irrigating post spaces with ascorbic acid solution before luting FRC posts significantly improves their bond strength compared to irrigation with EDTA solution. Irrigation with QMix solution produced the second highest retentive strength but showed no statistical significance when compared to using ascorbic acid, NaOCl, CHX, or EDTA solutions.

UNASSIGNED: Ultrasonic vibration for metallic post removal seems to be a unanimous choice between endodontists and general practitioners for providing the best results and having the highest safety. This study compared the time required by ultrasonic vibration for removing metallic post (MP) when 1 or 2 ultrasonics devices are used.
UNASSIGNED: One hundred and fifteen teeth with MPs from 105 patients, indicated for nonsurgical endodontic retreatment were divided into 2 groups according to the number of ultrasonic devices used (G1-1 device) and (G2-2 devices). In G1, the MP was worn with a transmetal bur, alongside the wear of the cement line (around 2 mm deep). Then, an ultrasonic tip attached to an ultrasonic unit, with a power of 100% was activated at the level of the post, with constant water spray at a level of 1 mm above the axial surface of the tooth. The position of the tip was changed between buccal and lingual surfaces every 10 seconds until the MP was removed. In G2 the same procedures were performed as described in G1, but two ultrasonic tips were activated simultaneously at buccal and lingual surfaces until the MP was removed. The vibration time necessary for removing each MP was recorded using a chronometer.
UNASSIGNED: The mean time was 131.10±29.68 seconds (mean±standard error of the mean) for MP removal using one ultrasonic device, and 24.86±6.88 seconds for two devices. The time required for MP removal using two ultrasonic devices was significantly less than when using one ultrasonic device (P<0.001).
UNASSIGNED: The technique with 2 ultrasonic devices proved to be more efficient than the one using only 1 ultrasonic device.

BACKGROUND: An optimum restoration for reconstructing endodontically treated teeth should provide excellent marginal adaptation, high fracture resistance as well as maximum tooth structure conservation. The purpose of this study was to evaluate the marginal adaptation and fatigue resistance of different coronal restorations in endodontically treated premolars.
METHODS: Thirty sound maxillary first premolars were endodontically treated and received MOD cavities. Teeth were randomly allocated into three groups (n = 10) according to the type of coronal restoration: Group R: polyethylene fibers (ribbond), fibers-reinforced composite (everX posterior) and final layer of nano-hybrid composite. Group O: indirect lithium disilicate overlay and Group C: fiber-post, resin composite restoration, and lithium disilicate crown. Marginal gap assessment was performed before and after thermocycling (5000 cycles) using stereomicroscope. Samples were subjected to stepwise-stress loading starting at 200 N, and increased by 100 N in each step until failure occurred. Statistical analysis was done by One-way ANOVA followed Tukey`s Post Hoc test for multiple comparison. Paired t test was used to compare the marginal adaptation before and after thermocycling. Survival probability was evaluated by Life table survival analysis. Failure mode analysis was performed with Chi-square test.
RESULTS: Marginal gap was significantly the lowest in group R (37.49 ± 5.05) and (42.68 ± 2.38), while being the highest in group C (59.78 ± 5.67) and (71.52 ± 5.18) in before and after thermocycling respectively (P < 0.0001). Fatigue resistance was the highest for group O (1310.8 ± 196.7), and the lowest for group R (905.4 ± 170.51) with a significant difference between groups (P < 0.0001). Crown group had the highest percentage (80%) of catastrophic failure, while, overlay group exhibited the lowest (20%).
CONCLUSIONS: Direct restoration without cuspal coverage using ribbon fibers with short FRC provided better marginal adaptation than indirect overlays and crowns, but fatigue resistance wasn\'t significantly improved. Adhesive ceramic overlays showed the best fatigue performance and the least catastrophic failure rate compared to both direct fiber-reinforced composite and indirect ceramic full coverage restorations.
CONCLUSIONS: Indirect adhesive overlays are a suitable, more conservative restorative option for endodontically treated teeth than full coverage restorations, especially when tooth structure is severely compromised.

UNASSIGNED: Dental post and core is one of the common procedures performed after endodontic treatment. The aim of this study was to radiographically assess the quality of post and core procedures performed by dental students at different education levels in addition to determining the most critical errors encountered during their clinical practice.
UNASSIGNED: A retrospective cross-sectional study design was conducted in the College of Dentistry, Imam Abdulrahman Bin Faisal University. A total of 550 periapical radiographs (PAs) of cemented posts were retrieved from the records of patients treated by dental students. Parameters and guidelines for assessing the quality of post treatment have been determined and statistically analyzed. A P value <0.05 was considered statistically significant.
UNASSIGNED: The study included 502 students and most of them were females (66.5%). Data were obtained from 502 patients (62% females) with fiber posts used in 98.2% of the cases. About 50% of the posts were inserted in premolars, 62.9% in the upper arch, and 66.7% were restored with crowns as a final restoration. Regarding the quality of posts, 98.4% showed good preparation quality and 98% showed good radiographic quality. The post diameter was equal to 1/3 of the root diameter in 31.9% of the cases; post length was equal to 2/3 of root length in 5% of the cases and equal to or more than crown height in all cases (100%). Length of the remaining gutta percha (GP) was between 3-5 mm in 38.8%, and there was no gap between the post and remaining GP in 95.6% of the cases. There were no statistically significant differences between dental students at different clinical educational levels regarding the quality of post placement.
UNASSIGNED: The quality of post and core procedures performed by students showed acceptable radiographic quality and were within the recommended standards.

BACKGROUND: In conjunction with post placement in root-filled teeth with periapical healthy conditions, root canal retreatment may be performed to improve the seal of the root canal. Whether root canal retreatment for technical reasons (retreatments in teeth without apical periodontitis (AP)) results in lower frequency of AP is unknown.
OBJECTIVE: To examine whether there is a difference in frequency of AP between roots with root canals retreated for technical reasons, and roots with root canals not retreated before post placement, with a minimum follow-up of 5 years. Also, to examine changes in root filling quality following root canal retreatment for technical reasons.
METHODS: This retrospective study included radiographs of 441 root-filled roots without periapical radiolucencies at baseline, scheduled for post and core treatment. Follow-up data for a minimum of 5 years were available for 305 roots (loss to follow-up 30.8%), 46 of which were retreated for technical reasons. Two calibrated observers assessed root filling sealing quality and length, respectively, and periapical status according to the Periapical Index. The main outcome of the study, AP, was used as the dependent variable and all analyses were performed at root level.
RESULTS: The overall frequency of AP at follow-up was 13.8%. The difference in frequency of AP between retreated (4.3%) and nonretreated (15.4%) root canals was not statistically significant, p = .061. Analyses including only roots with preoperatively inadequate root filling quality showed a statistically significant difference (p = .017) between the two treatment groups (2.4% vs. 22.9%).
CONCLUSIONS: Root canal retreatment for technical reasons before post and core placement significantly reduces the frequency of AP in roots with inadequate root filling quality.

OBJECTIVE: This study investigated the impact of common surface pretreatments on the contact angle (CA), surface free energy (SFE), and push-out bond strength (PBS) of custom 3D-printed resin posts.
METHODS: Post spaces of 60 endodontically treated mandibular premolars were prepared. Custom 3D-printed posts made from permanent crown resin were fabricated for 50 randomly selected post spaces. The specimens were then divided into six groups (n = 10) based on their surface pretreatment methods. These methods included sandblasting (SB), silane (SL), hydrofluoric acid (HF), and hydrogen peroxide (HP). Additionally, two control groups were established: glass fiber control (GFC) and permanent resin control (PRC). CA and SFE were measured for each 3D-printed post group. PBS and failure mode analyses were conducted. The data were analyzed using the two-way ANOVA followed by the Tukey post hoc test (α = .05).
RESULTS: The lowest CA values were found in the SB and SL groups. The SB group had the highest SFE compared to all other groups. SL markedly enhanced the PBS of the resin post compared to the PRC at the cervical, middle, and apical levels (P = .001, P = .000, and P = .002, respectively), and the values were comparable to those of the GFC (P = .695, P = .999, and P = .992, respectively). Except in the GFC, SB, and SL groups, mixed failure decreased from the cervical to apical levels, while adhesive failure rates increased.
CONCLUSIONS: The application of silane and sandblasting to the surfaces of custom 3D-printed resin posts effectively increased their SFE, thereby enhancing their adhesion.

UNASSIGNED: For placement of intraradicular posts the intracanal filling material has to be removed. If drills are employed for this purpose, extra widening of the canal, incomplete cracks or root perforation are probable when inappropriate size of drill is used.
UNASSIGNED: This in vitro study assessed the efficacy of radiographs taken after completion of root canal therapy in selecting the appropriate-sized Peeso reamer for post space preparation.
UNASSIGNED: Canals of 53 extracted maxillary and mandibular teeth of different types were cleaned and shaped. Then with acrylic resin 3-dimensional model of the intracanal space of each tooth was fabricated. Next, all canals were filled with gutta-percha and teeth were radiographed buccolingually. Based on these radiographs two observers selected a Peeso reamer that best matched each canal\'s diameter. The diameter of the selected Peeso reamer was compared to the diameter of the corresponding resin model of each canal by two independent observers and the difference was measured. The data were analyzed by paired sample t-test using SPSS version 22.
UNASSIGNED: The diameter of the selected Peeso reamers ranged from 0.21 mm smaller to 0.12 mm larger than the diameter of intracanal spaces. The difference between reamer and resin model was less than 0.1 mm in 75% of the cases.
UNASSIGNED: The result of this study suggests that post-operation endodontic radiographs are reliable means for selecting a size of Peeso reamer that does not encroach on dentinal wall during removal of intracanal filling material and post space preparation.

This randomized, controlled clinical trial compares the clinical performance of glass-fibre and resorbable polylactic acid (PLA) intracanal posts used to restore carious primary incisors in young patients. The study sample includes 180 primary upper central incisors of 90 children aged 3 to 4 years. All patients were randomly divided into two equal groups of 45 children who received PLA and glass-fibre (GFP) intracanal posts. The clinical assessment of incisor restorations was carried out immediately upon completion and at months 3, 6 and 12 according to the following criteria: anatomical form, marginal adaptation, surface roughness, marginal pigmentation, colour match, secondary caries and contact point. The Gingival Index (GI), the Bleeding Index (Cowell modification; mBI), and bite force (BF) were measured. At the 3-month follow-up, the occlusal BF of patients who received PLA posts was higher than the baseline; the GI and mBI scores were lower, by contrast (p < 0.05). This tendency was even more pronounced 6 and 12 months after the restoration. The incidence of side effects or symptoms (apical inflammation, cervical fracture, loosening of the crown) after the PLA posts was significantly lower than after the GFP (p < 0.05). No statistically significant differences were present between the two groups with respect to colour matching, anatomical form, marginal adaptation, marginal pigmentation, surface roughness, occlusal contact and secondary caries. Based on the results, applying PLA intracanal posts and cyanoacrylate to residual anterior crowns in young children can improve their gingival health, reduce side effects, and increase the likelihood of successful restoration.

BACKGROUND: The aim of this study was to investigate the feasibility of a real-time three-dimensional dynamic navigation system (3D-DNS) for post space preparation (PSP) in root canal-treated teeth and to compare the accuracy and efficiency of 3D-DNS to freehand (FH) for PSP.
METHODS: Fifty-four maxillary molars were divided into two groups: 3D-DNS (n = 27) and FH group (n = 27). Cone beam computed tomography (CBCT) scans were taken preoperatively and postoperatively. The drilling path for the PSP was virtually planned in the preoperative CBCT scan in the X-guide software (X-Nav Technologies, Lansdale, PA). For the 3D-DNS group, the PSP drilling was conducted under dynamic navigation. The 3D deviations and angular deflections were calculated. The residual dentin thickness (RDT) was determined after PSP. The operation time and the total number of mishaps were recorded. Shapiro-Wilk, t-test or Mann-Whitney rank sum, weighted Cohen\'s kappa, and Fisher exact tests were used (P < .05).
RESULTS: The PSP was completed in all samples (54/54). The 3D-DNS was more accurate than the FH, with significantly fewer 3D deviations and angular deflections (all, P < .05). The 3D-DNS required less operating time than the FH (P < .05). For the 3D-DNS, no teeth had RDT < 1 mm, whereas 6/27 in the FH showed RDT < 1 mm after the PSP. There was no difference in the total number of mishaps (P > .05).
CONCLUSIONS: Within the limitations of this in vitro study, the 3D-DNS is feasible for PSP. The 3D-DNS improved the accuracy and efficiency of PSP. The dynamic navigation system can potentially become a safe and reliable technology for PSP.