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Background This study used micro-computed tomography (µCT) to assess the post space preparation systems [Rebilda (VOCO), RelyX (3M)] and preparations of varying lengths to create root dentin cracks. Methods Forty extracted maxillary first premolars with two roots were randomly divided into four groups. Teeth were decoronated to a length of 18 mm. Following root canal treatment, first µCT scans were performed. Post spaces were prepared with Rebilda post drills at 1/2 of the working length (WL) in Group 1 and at 2/3 of the WL in Group 2, while post spaces were prepared with RelyX post drills at 1/2 of the WL in Group 3 and at 2/3 of the WL in Group 4. After post space preparation, second µCT scans were performed. Dentinal cracks were detected by comparing the first and second µCT scan images, which were classified as “newly formed cracks”, “advanced cracks” and “completed cracks”. The chi-square test was used to compare among the groups, with a p-value of < 0.05 considered statistically significant. Results No statistically significant differences were observed between the groups for completed and advanced cracks ( P  > 0.05). In terms of newly formed cracks, the Rebilda-2/3 group showed more cracks than the RelyX-1/2 group, and the RelyX-2/3 group had more cracks than the RelyX-1/2 group ( P  < 0.05). Conclusion Completed and advanced cracks were observed in all groups, while no newly formed cracks were detected in the RelyX-1/2 group. The type of post drill and the preparation length are crucial factors in preventing the development of root dentinal cracks. Preparing 1/2 of the canal length may be a safer preparation length, and the RelyX drill may pose less risk of inducing root dentinal cracks.

Objective This study evaluated the effect of different impression and fabrication techniques—conventional casting and 3D printing—on the precision of metal post‐and‐core restorations. Methods and Materials A maxillary central incisor was designed in ExoCAD, and STL files of the reference tooth and the “ideal” post were saved; the reference tooth was additively manufactured in metal. Four workflows were compared (n = 10/group): (1) conventional impression with a direct resin pattern and casting (CO); (2) semi‐digital impression with an intra‐canal Duralay pattern plus Silicone pick‐up, laboratory scan, and direct metal printing (DS); (3) semi‐digital Full Silicone (putty/wash) impression, laboratory scan, and direct metal printing (FS); and (4) fully digital intraoral scanning with Medit i700 and direct metal printing (FD). For each specimen, the fabricated post STL was compared to the “ideal post” STL in Geomagic Control X to assess precision. Normality was tested with Shapiro–Wilk, and between‐group comparisons used one‐way analysis of variance in SPSS (α = 0.05). Results In forty specimens (FD, DS, FS, CO; n = 10/group), three outcomes were analyzed: In‐Tol, Over‐Tol, and Under‐Tol. In‐Tol differed significantly among groups (p < 0.001); Tamhane's T2 indicated FD > DS, FS, CO (p = 0.006, < 0.001, < 0.001). Over‐Tol differed significantly (p < 0.001); FD < FS (p < 0.001), FD < CO (p = 0.021), and DS < FS (p < 0.001). Under‐Tol also differed significantly (p < 0.001); DS > FD (p = 0.027), DS > FS (p = 0.011), and CO > FS (p = 0.016). Conclusion Fully digital, directly printed Co–Cr posts exhibited superior precision compared with conventional and semi‐digital workflows. While conventional casting remains reliable, direct metal printing appears to be a practical and potentially easier alternative.

Background Intraoral scanning of post spaces offers a potential alternative to conventional impressions, but its effectiveness depends on overcoming limitations influenced by post space dimensions. Aim of the study This study aimed to evaluate the trueness and depth discrepancy percentage of scanned post spaces with different dimensions using an intraoral scanner. Materials and methods Twenty single-rooted human maxillary canines were endodontically treated. Teeth were assigned to two post space preparation width groups: N (Ø1.5 mm) and W (Ø1.7 mm) ( n  = 10 per group). Each width group was further subdivided into two depth subgroups: S (6 mm) and L (10 mm) ( n  = 5 per subgroup). This resulted in four experimental subgroups: NS (Ø1.5 mm, 6 mm), NL (Ø1.5 mm, 10 mm), WS (Ø1.7 mm, 6 mm), and WL (Ø1.7 mm, 10 mm). Specimens were scanned using the Panda P2 intraoral scanner (IOS), and the obtained STL files were aligned and compared with those from traditional impressions scanned with the InEos X5. Trueness and depth discrepancy percentage were evaluated using reverse engineering software. The data were statistically analysed using a Two-Way ANOVA, followed by multiple pairwise comparisons using Tukey’s HSD for each individual factor. Results Preparation width had no significant effect on trueness ( p  > 0.05), whereas increasing preparation depth significantly reduced it. Additionally, a greater preparation width significantly decreased the depth discrepancy percentage, while increasing preparation depth led to a significant increase. A statistically significant, very strong positive correlation was observed between RMS and depth discrepancy percentage ( r  = 0.898), indicating that greater deviations in trueness were associated with increased depth discrepancies. Conclusions Within the study’s limitations, trueness improved by reducing post space depth and remained clinically acceptable for all subgroups. However, increasing depth to 10 mm raised the depth discrepancy beyond the clinically acceptable range, while decreasing width also increased discrepancy. Clinical trial number Not applicable.

In this study, we evaluate the influence of post surface pre-treatments on the bond strength of four different cements to glass fiber posts. Eighty extracted human maxillary central incisors and canines were endodontically treated and standardized post spaces were prepared. Four post pre-treatments were tested： （i） no pre-treatment （NS, control）, （ii） sandblasting （SA）, （iii） silanization （SI） and （iv） sandblasting followed by silanization （SS）. Per pre-treatment, four dual-cure resin cements were used for luting posts： DMG LUXACORE Smartmix Dual, Multilink Automix, RelyX Unicem and Panavia F2.0. All the specimens were subjected to micro push-out test. Two-way analysis of variance and Tukey post hoc tests were performed （α=0.05） to analyze the data. Bond strength was significantly affected by the type of resin cement, and bond strengths of RelyX Unicem and Panavia F2.0 to the fiber posts were significantly higher than the other cement groups. Sandblasting significantly increased the bond strength of DMG group to the fiber posts.

In endodontically treated teeth, cuspal coverage plays a fundamental role in reducing the risk of fracture. However, the adhesive techniques with or without fiber post increased the possibilities in restoring root-filled teeth. The aim of this study was to determine the effect of the fiber post and/or post length and/or cuspal coverage on the fracture resistance of endodontically treated maxillary premolars. Seventy intact single-rooted maxillary premolars were selected and divided in seven groups of ten each: “intact teeth” (control), “inlay without fiber post” (G1), “inlay with long fiber post” (G2), “inlay with short fiber post” (G3), “onlay without fiber post” (G4), “onlay with long fiber post” (G5), and “onlay with short fiber post” (G6). Except for intact teeth, all specimens were prepared with a mesio–occluso–distal (MOD) cavity, endodontically treated and restored with or without long or short post, with or without cusp coverage. All specimens were thermal-cycled, exposed to a cyclic loading, and then submitted to the static fracture resistance test. Fracture loads and mode of failure were evaluated. A statistically significant difference in fracture resistance was found between group 1 and the other groups ( p  < 0.001). χ 2 test showed statistically significant differences in the patterns of fractures between the groups ( p  < 0.001). The highest number of favorable fractures was observed in groups 3 and 4. Similar fracture resistance was detected in maxillary premolars endodontically treated with MOD cavity preparations, restored with either direct resin composite with fiber post or cusp capping. The “short post” direct restoration may be a valid alternative in the restoration of root-filled premolars.

Objective The purpose of this study was to assess current opinions, applied techniques, and materials for the restoration of endodontically treated teeth (ETT) in a nationwide survey in Germany. Material and methods Completed questionnaires from 1,648 dentists were returned (response rate 63 %). Results In general, posts were reported to be used more frequently (51 %) for indirect restorations than for direct restorations (21 %). Dentists restored anterior teeth (65 %) more frequently with direct restorations than posterior teeth (48 %). Compared to an earlier survey, fewer dentists stated that posttreatment stabilizes the remaining tooth structure. The ferrule effect as a key success factor was held by the vast majority of dentists (88 %). A trend towards adhesive techniques both for post placement and core build-up was observed. Composite resins (49 %) were reported to be used twice as much as zinc phosphate cement (24 %) for the luting of posts; composite resins were the core build-up material of choice (75 %). Amalgam was rarely used (0.2 %). Irrespective of the final restoration, fiber posts were the most popular post material (46 % for telescopic crowns vs. 69 % for single crowns). Conclusion Adhesive composite core build-ups with and without fiber posts were the predominant treatment approach to restore ETT in Germany. There was widespread agreement with the ferrule effect as a key restorative success factor for indirect restorations. Clinical significance Today, it is general accepted that ferrule preparation is key. Glass-fiber posts appear to be most popular. Still different systems are used depending on type of final restoration, while the reasons to do so remain unclear.

Purpose: The aim of the present study was to clinically evaluate and compare the efficacy and retention of various types of intracanal posts in the restoration of grossly decayed deciduous anterior teeth. The various posts used were polyethylene post, glass post, and composite post. Materials and Methods: A total number of 16 patients with 45 grossly decayed primary anterior teeth were selected. After biomechanical preparation and obturation, patients were randomly divided on the basis of posts to be used into three groups (Group I: Polyethylene post; Group II: Glass post, and Group III: Composite post). Then, space was created in the obturated canal and posts were placed, followed by core build up. Results: After an interval of 12 months, 86.67% of the teeth exhibited complete retention of the post restored with polyethylene post (P > 0.005) and 93.3% of the teeth exhibited complete retention of the post that were restored with glass post (P > 0.005) whereas only 60% of the teeth exhibited complete retention of the post that were restored with composite post (P< 0.005). Only 20% of the teeth exhibited marginal discoloration in both Groups I and III and 13.33% in Group II and this was nonsignificant. Conclusion: Both glass post and polyethylene post proved to be effective. Glass post showed the maximum retention and marginal adaptation followed by polyethylene post. Thus, it appears to be of potential interest for use especially in clinical pediatric dentistry.

This study aimed at evaluating the post-root dentin push-out bond strength of circular and oval posts luted in oval-shaped canals with two different resin cements. Twenty extracted premolars with oval-shaped canals were selected, endodontically instrumented and obturated. The teeth were divided into two groups according to the drill used for post-space preparation and to the post shape (Ellipson oval tip + post and MTwoPF + DT Light-Post). Each group was then subdivided into two subgroups according to the cement (Gradia Core and Corecem Automix). The post-dentin bond strength was evaluated with the thin-slice push-out test. The bonded surface area was calculated for each post shape with an appropriate geometric formula in order to express the retentive strength in megapascal. Push-out strength data were analyzed with the Kruskal–Wallis ANOVA. The results showed that neither the drill-post system nor the cement significantly affected the push-out strength. The means (SD) of the push-out bond strengths in the experimental subgroups were the following: 11.79 MPa (4.77) for Gradia Core/Ellipson tip and post, 13.36 MPa (5.16) for Gradia Core/MtwoPF and DT Light-Post, 11.18 MPa (2.58) for Corecem Automix/Ellipson tip and post, and 10.91 MPa (3.89) for Corecem Automix/MtwoPF and DT Light-Post. In conclusion, circular and oval posts achieved similar retentive strengths in oval canals.

Objectives The aim of this study was to evaluate the effect of post system and length on the fracture resistance of endodontically treated human anterior teeth. Material and method Seventy-five extracted human incisors were endodontically treated, out of which 60 were decoronated 2 mm above the cementoenamel junction and divided into two experimental groups based on the type of post system to be used: glass fiber post (GFP) and Ribbond fiber post groups (RFP). Endodontically treated human anterior teeth in which no post was placed served as control group. Each group was divided into two subgroups according to the length of post space: 5 and 10 mm and all the samples were restored with metal crowns. The fracture resistance was measured by applying loads at an angle of 130° to the long axis of teeth in an Instron universal testing machine. Results The results revealed that GFP group at 10-mm post space length showed the significantly highest fracture resistance (740.2133 N) among all groups and subgroups. Decrease in post length resulted in the decrease in fracture resistance in GFP group (425.1867 N), whereas in group RFP 5-mm subgroup (299.6200 N) showed significantly higher fracture resistance than 10-mm subgroup (216.9300 N) but lesser than the control (437.8733 N) in both the subgroups. Conclusion Glass fiber posts efficiently increase the fracture resistance of an endodontically treated tooth but the determination of optimal post length is also essential. Clinical relevance The present investigation highlights the significance of using glass fiber posts in the restoration of endodontically treated teeth. Endodontically treated teeth restored with glass fiber posts showed increased fracture strength and favorable mode of fracture, and are therefore highly recommended to achieve better clinical outcomes.

The purpose was to investigate by push-out tests and scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) the effect, after first acid etching the post space walls, of three radicular dentine treatments on the regional bond strength of quartz fibre posts placed using two heavily filled resin luting cements. The crowns of 39 extracted maxillary central incisors were sectioned transversely 2 mm coronal to the labial cement-enamel junction and the roots endodontically treated. After standardized post space preparations and etching 15 s with 32% phosphoric acid, 36 roots were randomly divided into six equal groups. Quartz fibre posts (D.T. LIGHT-POST) were placed using three radicular dentine treatments (0.9% sodium chloride (NaCl) for 60 s, 10% sodium hypochlorite (NaOCl) for 60 s, 17% ethylenediaminetetraacetic acid (EDTA) for 60 s followed by 5.25% NaOCl for 60 s) and two resin composite luting cements (ONE-STEP PLUS/DUO-LINK; ONE-STEP PLUS/LuxaCore Dual). Transverse segments (S1–S7), 1.00 mm (SD = 0.05 mm) thick, were sectioned from the coronal 8 mm of each root. Push-out bond strength tests were performed on coronal, middle and apical post space segments (S2, S4, S6) at a crosshead speed of 0.5 mm/min. Data were recorded and analyzed using a two-way mixed ANOVA design ( a  = 0.05). Three segments (S1, S5, S7) from roots in each group were examined using SEM/EDS. After post space preparation, acid etching and using each of the three radicular dentine treatments, the three remaining roots were sectioned longitudinally for SEM observation of the post space walls. At all root segment sites, the mean bond strengths from using 0.9% NaCl were significantly lower than for the other two radicular dentine treatments ( P  ≤ 0.02), and DUO-LINK cement had significantly higher mean bond strengths than LuxaCore Dual cement ( P  ≤ 0.01). There was a significant linear trend for reduced bond strengths from coronal to apical post space segments ( P  < 0.001), which was supported by the SEM/EDS observations of dentine tubule appearance and resin tag formation. Acid etching followed by either 10% NaOCl or 17% EDTA and 5.25% NaOCl dentine treatments of the post spaces provided good adhesion and resin luting cement tag infiltration of dentinal tubules in the coronal and middle segments in particular.