Cast Posts Research Articles

The Accuracy of Custom-Made Milled Metal Posts as Compared to Conventional Cast Metal Posts.

The aim of this study was to compare the fitting accuracy of custom-made metal posts and cores fabricated by half-digital and milling technique to that of conventional cast posts fabricated by direct technique. Sixteen extracted single-rooted teeth were endodontically treated followed by post space preparation. A direct resin post and core pattern was made for each tooth and used for the fabrication of two posts (n = 16). Each post resin pattern was digitized with a laboratory scanner and used for the fabrication of a milled cobalt-chrome (Co-Cr) alloy post, while the direct resin pattern, after scanning, was cast in a Co-Cr alloy to produce a cast post. Each post was seated on its respective tooth and evaluated using microcomputed tomography. The following variables were evaluated: total space volume between the post and root canal, the volume and distance of the apical gap between each post and the remaining apical root canal filling, as well as the distance and surface area of the space between the post and lateral root canal wall at four determined points along the length of each post. The results revealed that half-digital and milled posts had a statistically significantly higher total space volume (p < 0.05), apical gap volume (p < 0.02) and distance (p < 0.02), as well as a higher surface area of space between the post and root canal wall at the cervical area as compared to the cast post (p < 0.05). This study demonstrated that the fitting accuracy of cast posts was more accurate than posts fabricated with half-digital and milling technique.

Is a Pre-Existent Cone-Beam Computed Tomography Able to Detect Metal Dental Posts?

(1) Background: In this study, the efficacy of cone-beam computed tomography (CBCT) in detecting dental posts was compared to periapical radiography. (2) Methods: A retrospective evaluation of 53 patients' periapical radiographs and CBCT images was performed. The presence and type of the intra-canal dental post were initially determined on the periapical images (PA) radiographs' examination and were then compared to the observer's ability to detect the dental post on a CBCT image. The effect of the post's type (metal cast or prefabricated) on its detection on CBCT images was determined. (3) Results: 10.5% of teeth that were identified as having a post on a PA radiograph were not identified as having a post on the CBCT examination (p < 0.05). Approximately 17.6% of teeth that were identified as not having a post on a PA radiograph were identified as having a post on the CBCT examination (p < 0.05). Moreover, 16.3% and 50% of teeth with a prefabricated or cast posts on PA radiographs were falsely identified on the CBCT examination, respectively (p < 0.05). (4) Conclusions: A CBCT image is an insufficient tool for the identification of metal prefabricated and cast posts. A PA image is the recommended radiographic tool for achieving information about the post-endodontic restoration status of teeth candidates for endodontic retreatment in patients with a former CBCT scan.

THE ACUTE MANAGEMENT OF PILON FRACTURES (ENFORCE) STUDY: A TRAINEE-LED NATIONAL COLLABORATIVE EVALUATION OF PRACTICE

IntroductionTibial Pilon fractures are potentially limb threatening, yet standards of care are lacking from BOFAS and the BOA. The mantra of “span, scan, plan” describes staged management with external fixation to allow soft tissue resuscitation, followed by a planning CT-scan. Our aim was to evaluate how Tibial Pilon fractures are acutely managed.MethodsENFORCE was a multi-centre retrospective observational study of the acute management of partial and complete articular Tibial Pilon fractures over a three-year period. Mechanism, imaging, fracture classification, time to fracture reduction and cast, and soft tissue damage control details were determined.Results656 patients (670 fractures) across 27 centres were reported. AO fracture classifications were: partial articular (n=294) and complete articular (n=376). Initial diagnostic imaging mobilities were: plain radiographs (n=602) and CT-scan (n=54), with all but 38 cases having a planning CT-scan. 526 fractures had a cast applied in the Emergency Department (91 before radiological diagnosis), with the times taken to obtain post cast imaging being: mean 2.7 hours, median 2.3 hours, range 28 mins – 14 hours). 35% (102/294) of partial articular and 57% (216/376) of complete articular (length unstable) fractures had an external fixator applied, all of which underwent a planning CT-scan. Definitive management consisted of: open reduction internal fixation (n=495), fine wire frame (n=86), spanning external fixator (n=25), intramedullary nail (n=25), other (n=18).ConclusionThe management of Tibial Pilon fractures is variable, with prolonged delays in obtaining post cast reduction radiographs, and just over half of length unstable complete articular fractures being managed with the gold standard “span, scan, plan” staged soft tissue resuscitation. A BOFAS endorsed BOAST (British Orthopaedic Association Standard for Trauma) for Tibial Pilon fractures is suggested for standardisation of the acute management of these potentially limb threatening injuries, together with setting them apart from more straightforward ankle fractures.

A case report on the rehabilitation anterior teeth using custom made post and pre fabricated fiber post and core

Posts are recommended to fortify weak, endodontically treated teeth against intra-oral forces by channeling torquing forces through the radicular dentin to supportive tissue along the roots. The subsequent case studies demonstrate an interdisciplinary approach that employed custom cast posts and complete veneer crowns to repair severely damaged treated teeth, restoring both their appearance and functionality. Coordinating prosthetic and endodontic treatments, while carefully considering the patient's expectations and requirements, played a pivotal role in achieving positive outcomes and ensuring patient satisfaction. Traditionally, the cast metal post and core system has been widely used as the foundational restoration for a prosthetic crown, benefiting from a natural extension of the post within the core. The post's function is to bolster the core restoration, which rebuilds the compromised coronal structure. This article explores the utilization of cast post and core systems alongside porcelain-fused-to-metal restorations for addressing injured maxillary central incisors.

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.

Restorative Modalities for Structurally Compromised Teeth with Thin-walled Roots: A Literature Review

AbstractProper restoration and maintenance of endodontically treated teeth with thin-walled roots and immature apices is of a great concern due to the high prevalence of such cases. The aim of this study was to review the efficiency of different materials used for post–core systems in order to restore endodontically treated teeth. A literature review was conducted using electronic databases including PubMed, Scopus, Web of Science, and Google Scholar to find relevant articles. Randomized controlled trials that were related to different post–core techniques for restoring endodontically treated teeth and were in the English language were included from 2000 until 2022. Most articles concluded that cast posts have higher fracture resistance than fiber posts. All articles comparing stainless steel posts with other materials found that it had higher fracture strength. No particular difference between various types of fiber posts was identified, and all can reinforce the immature roots with thin dentinal walls.

Experimental study on seismic behavior of T-joints of composite shell system with prefabricated underground pipe gallery

The prefabricated assembly structure adopts a new joint structure and construction method, which has the advantages of low environmental pollution, high construction quality, and less traffic interference. At present, prefabricated structures have been widely used in the field of building construction and bridge engineering, but less in the application of underground comprehensive pipe gallery. In view of this, this paper proposed a new type of assembled composite shell system underground comprehensive pipe gallery structure. The formwork is made of high-performance materials, and connectors are set between the formwork, and the load-bearing reinforcement of the composite shell pipe gallery component was set outside the formwork. Quasi static tests were carried out on 6 specimens of composite shell pipe gallery T-joints to study the mechanical properties of the joints and the integrity of the connection interface. The results show that the bearing capacity, stiffness and ductility of composite shell T-joints are basically equivalent to those of cast-in-place (CIP) reinforced concrete shear walls, which verifies the good seismic performance of fabricated joints. When the specimen is in the yield and bearing capacity state, the joint surface between the formwork and the post cast concrete is good, which can effectively ensure that the formwork and the concrete maintain the common force. The bearing capacity of upper and lower T-joints of composite shell with shear reinforcement is 10∼15% higher than that of CIP structure. In addition, a calculation formula for the bearing capacity of the T-shaped joint of the composite shell was proposed and its accuracy was verified through test results. This study can provide technical support for seismic design of prefabricated underground pipe gallery.

SEM and EDS comparative studies about the homogeneity of some cements used for luting of posts

Objectives. The aim of the study was to evaluate comparatively by scanning electron microscope (SEM) and energy dispersive spectrophotometry (EDS) the physical and chemical homogeneity of some luting materials used for cementation of three types of posts. Materials and method. We selected 12 irretrievable monoradicular teeth extracted in our dental offices. After extraction, all teeth were prepared for cementation with 4 different cements (NANOCORE DUAL, CEMBEST, PANAVIA SA and CEMENT-ONE) of three types of posts: prefabricated titanium post, FibreKleer 4x fiberglass post (Pentron) and post cast from NiCrMo alloy. Afterwards, the samples were embedded in resin and prepared metallographically for examination with the Phenom ProX scanning electron microscope equipped with an energy dispersive spectrophotometer with X Rays. Results. SEM studies provide valuable ultrastructural information regarding the degree of filling with luting materials. The four studied cements do not present an inhomogeneous composition in the EDS analysis, not having significantly increased values between the 2 analyzed points for each of the 12 samples taken in the study. Conclusions. Among the four luting materials studied comparatively, PANAVIA SA seems to best fill the existing spaces between posts and the limits of dental preparations, being closely followed by CEMENT-One and CEMBEST. In last place is NANOCORE DUAL, which presents discontinuities in the mass of material and at the border with the preparations.

Effect of Ferrule Location on Fracture Resistance of Maxillary Premolars: An In Vitro Study.

The present study aimed to assess the effect of ferrule location on fracture resistance of maxillary premolars. A total of 72 extracted human maxillary premolars were selected and randomly assigned to six groups (n = 12 in each) considering ferrule location: circumferential ferrule (CF), without ferrule (WF), buccal ferrule (BF), lingual ferrule (LF), mesial ferrule (MF), and buccal-lingual ferrule (BLF). Cast posts were cemented into the prepared post spaces. Following conventional impression, Ni-Cr crowns were cemented to the specimens. After thermocycling (5,000 cycles, 5-55°C), the specimens were loaded at 45° in a universal testing machine until fracture. Data were analyzed with one-way ANOVA, Kolmogorov-Smirnov, and Tamhane tests. The maximum and minimum mean fracture resistance were related to the CF (1,143.84 N) and WF (514.89 N) groups, respectively, (P = 0.039). Fracture resistance in the BF (933.67 N) and BLF (874.01 N) groups was significantly higher than in the MF group (617.54 N) (P = 0.001). There was no significant difference between the MF, LF (722.89 N), and WF groups in terms of fracture resistance (P > 0.05). Teeth with CF showed maximum fracture resistance. The location of the ferrule effects on the fracture resistance of maxillary premolars and also the mode of failure.

Knowledge of Saudi dental students and interns towards luting cements and their applications in fixed prosthodontics

BackgroundEnhancement of students’ knowledge is essential in improving their clinical skills and performance. Thus, the curriculum should be prepared to achieve a better outcome. The current study aimed to determine the dental students’ and interns’ basic knowledge towards dental luting cements and their application in dental practice to improve the theoretical and clinical training sections.Materials and methodsA cross–sectional study was conducted among dental students and interns at three Colleges of Dentistry in the Kingdom of Saudi Arabia between September 2019–June 2020. An online questionnaire was used which included demographic data, questions about luting cement usage, cementation techniques, and commonly used cements in dental clinics. Descriptive analysis and chi–square test were used to show the association between level of dental education and the use of dental cements using SPSS software. The significance level was set at 5%.ResultsThe total respondents were 626 dental students/interns of whom 78.8% were undergraduate dental students. Participants who reported undergraduate studies as the source of information were 79.7%. The type of restoration was the main factor in luting cement selection (62.6%). Concerning the isolation technique in cementing laminate veneers, 49.7% used dri–angles, cotton rolls and saliva ejectors. Dual–cure resin cement was the most common cement used in all the mentioned restorations except in pressed porcelain laminate veneers and cement–retained implant–supported restorations.ConclusionsStudents’ knowledge and practice in managing dental implants and porcelain laminate veneers need to be improved. The selection of a luting agent for a given restoration by students and interns was based on the basic knowledge, available cement, and the type of restoration. Awareness towards the management of short prepared teeth and custom-made cast posts and cores is also limited.

3D-printed concrete permanent formwork: Effect of postcast concrete proportion on interface bonding

Using 3D concrete printing technology to produce permanent formwork for building components is a promising method that maximizes design freedom and material savings. In this study, 3D-printed permanent formwork made of concrete with coarse aggregate is manufactured and post cast with concrete containing different coarse aggregate particle size ratios. The results indicate that the splitting tensile strength of the concrete interface reaches 2.3 ∼ 4.4 MPa, of which the reduction rate range from 12.8%∼35.7% with higher bonding positions. Mesoscopic observation reveals the voids concentration and a lack of coarse aggregate phenomenon in the interface area. Increasing the proportion of small-sized coarse aggregates in the pouring concrete can better fill and improve the splitting strength of the interface area.

Complete Occlusal Rehabilitation of a Grossly Decayed Natural Dentition Using Multiple Prosthodontic Options

Complete occlusal rehabilitation involves multiple disciplines and specialties of dentistry. Within Prosthodontics it requires meticulous planning of correcting existing occlusal problems and finding new biologically acceptable occlusal parameters which include centric occlusion, occlusal plane, aesthetic position of anterior teeth and vertical dimensions. Very less occlusal rehabilitations will be considered complete if the above parameters are not biocompatible with temporomandibular joint function. This case report of a 43-year-old housewife who presented with a chief complaint of grossly decayed natural teeth is one such case where the above parameters were all corrected. While extra oral parameters were within normal limits, intra oral dental condition was corrected by a series of extraction of teeth, endodontic (intentional and conventional), surgical crown lengthening and multiple prefabricated and cast post cores. The anterior guidance was established and corrected on the temporary restorations which was then transferred to the definitive restoration. Foundation restorations were built using multiple prefabricated fiber posts and custom made cast posts. Final restorations that included single crowns and multiple fixed partial denture were fabricated of metal ceramic. A cast partial denture was also part of the overall occlusal rehabilitation. At subsequent follow up, the patient was extremely satisfied with the outcome of the treatment.

Three-Dimensional Finite Element Study of Endodontically Treated Maxillary Central Incisors Restored Using Different Post and Crown Materials.

Restoring endodontically treated teeth is a common problem in dental practice. Post and core restorations are one of the major options in the rehabilitation of these teeth. However, there is no final decision regarding the best material or technique to be used with these restorations. So, this study aimed to evaluate the effect of different post and crown materials on the biomechanical behavior of restored maxillary central incisor using the finite element method. A total of 10 3D models of endodontically treated maxillary central incisors restored with two prefabricated posts and three custom-made posts were modeled and grouped according to post material (gold, nickel-chrome, zirconia, and glass fiber) and crown material (lithium disilicate, and zirconia). Finite element analysis was conducted, and stress distribution was evaluated using von Mises criteria. Both crown materials showed stress concentration at the force application site mainly on the intaglio palatal surface of the crown. However, more stress values were observed within zirconia crowns. All posts showed stress concentration at their buccal sides. However, more stress values were observed in zirconia and metal cast posts compared to glass fiber posts that transfer more stress to root dentin. Post and crown materials affect the stress distribution in the tooth-restoration complex. Using high elastic modulus posts slightly decreased stress in root dentin despite concentrating more stress within their structure. However, glass fiber posts resulted in more homogenous stress distribution in the tooth-restoration complex. Crown material did not influence the stress distribution in root dentin. Custom-made posts decreased stress within crowns, regardless of the crown material. However, more stress values were observed within zirconia crowns. Custom-made zirconia posts and cores showed a similar stress distribution as non-precious metal cast posts, so they may be used as a suitable option where esthetic is desirable.

The accuracy comparison of 3D-printed post and core using castable resin and castable wax resin.

The purpose of this research was to compare the accuracy of three-dimensionally (3D) printed post and core fabricated with two different materials: reinforced wax and castable resin. MATERIALSAND METHODS: Fifteen extracted single root central incisors were selected. Root canal treatment and tooth preparation for crown were performed on all teeth. Eleven millimeters post space was created with standardized prefabricated fiber post drill. Polyvinylsiloxane impression material was used for root canal impressions. Each impression was then 3D scanned using an extraoral scanner and cast posts and cores were designed using 3Shape software. The digitally designed post and cores were 3D printed with two different materials: castable wax resin and castable resin. The castable resin patterns were scanned before and after complete polymerization. The wax patterns were also scanned. Digital volumetric measurement using Geomagic® Control X™ software was performed to determine accuracy. The printed post and core had reduced volume (16.09± 3.839 mm3 ) compared to the digital design (17.828± 3.904, p < 0.05). Before complete polymerization, the accuracy of 3D printed resin pattern (16.464± 3.017) was found to be superior to post and core printed with wax (16.193± 3.018, p < 0.05). However, no volume difference was found between completely polymerized resin (16.09± 3.839) and wax (16.044± 3.834, p = 1). 3D printed post and core showed significant volume shrinkage from the digital files used to create them. However, different materials had no effect on the accuracy of 3D printed post and core.

Experimental and numerical investigation on collapse behavior of precast reinforced concrete beam-column sub-assemblages with cast-in-place ECC joints

In order to investigate the effects of engineering cementitious composite (ECC) used as post-cast materials and anchorage length of beam longitudinal rebars in the ECC cast-in-place joints on collapse behavior of precast reinforced concrete (PRC) structures, static pushdown collapse tests on scaled PRC beam-column (BC) sub-assemblages were carried out. Three BC sub-assemblage specimens having a double-span beam and a middle column joint were designed and fabricated with the same geometric dimensions, including one monolithic specimen BC0 and two PRC specimens BC1 and BC2. The specimen BC0 was cast in site with normal concrete, while the double-span beams of specimens BC1 and BC2 were first cast with normal concrete and then the middle column joint was post cast with ECC. The anchorage length of beam longitudinal rebars embedded into the middle joint was 29d, 20d, and 10d (d is the diameter of beam rebar) respectively for specimens BC0, BC1, and BC2, which could produce different splice length in the middle joint. On the basis of tests, refined finite element (FE) models were established and reasonably verified by a detailed comparison between numerical and experimental results. Based on the validated FE models, a parametric analysis was performed to study the effects of horizontal constraint stiffness, anchorage length, and bond strength between beam longitudinal rebars and ECC on collapse resistance of PRC sub-assemblages. The results showed that the application of ECC as the post cast material in the joint of PRC sub-assemblages could achieve similar collapse behavior to the monolithic counterpart and reduce the anchorage length of beam longitudinal rebars with a suggested lower limit of 20d. The bond strength between rebar and ECC in the joint had obvious influence on the collapse resistance and deformation capacity at large deformation stage.

Seismic performance research on precast wall-beam out-of-plane joint with ECC post-cast zone

In order to study the seismic performance of wall-beam out-of-plane joints with ECC post-cast area, seven specimens and one comparison specimen were designed considering the embeded method of reinforcement in the wall, the connecting method of reinforcement in the post cast area, the shear-to-span ratio, the slab width, etc, and the proposed static tests were carried out. The damage model, hysteresis performance, bearing capacity, stiffness degradation, and energy dissipation capacity of the specimens were analyzed and the simulation method based on the finite element software OpenSEES is given. The results show that: the use of ECC in the postcast area can effectively improve the ductility and load-bearing capacity of the specimens; the use of bent-up reinforcement lap, bent-hook reinforcement connection and sleeve connection for the reinforcement in the post-cast area can effectively transfer the reinforcement stress; the finite element analysis method proposed in this paper considering the slip of reinforcement and the characteristics of ECC material, has high accuracy and is suitable for application in engineering.

Measurement and optimization of multi-attribute characteristics in milling epoxy granite composites using rsm and combined ahp-topsis

Epoxy granite composites with its wide range of applications in machine tool industries are manufactured by molding process and require post cast machining operations to meet the desired dimensional accuracy for assembly of machine tool structures. In this research work, milling of epoxy granite composites are carried out based on the experimental design from Response Surface Methodology (RSM) techniques and further the optimal solutions are determined by a novel hybrid algorithm AHP-TOPSIS. Central Composite Design (CCD) model is applied with three factors-three levels and the measured output responses are thrust force, tangential force and surface roughness. Experimental combinations of 20 different trials are performed using high speed steel end mill cutter of diameter 10 mm with three levels of input parameters: speed; fibre content and feed rate at a uniform depth of cut. The relative importance matrix formulated proved to be highly consistent with its consistency ratio to a maximum of 0.000641 which lies below the higher range of 0.1. Consistency ratio of 0.000641 reveals that the optimal solutions determined will be highly reliable and the decision making is much more judicious. Optimal solution determined from hybrid AHP-TOPSIS methods are: speed 1800 rpm; feed rate 0.03 m min−1 and 0% percent fibre content. Functional relationships among parameters and responses established by RSM are consistent upto 95% and its significance is tested by analysis of variance. Comparison among predicted and experimental values of three measured responses convey that the percentage variations are minimum with up to 2.03% for surface roughness, 2.50% for thrust force and 2.71% for tangential force components. This research work provides a systematic procedure and clear framework for determination of optimal machining conditions by hybrid methodology on the basis of technique for order preference by similarity to ideal solution (TOPSIS) combined with analytical hierarchy procedure (AHP) for attribute weights and further analyzes the influence of machining parameters over measured responses.

Efficacy of CAD/CAM Glass Fiber Posts for the Restoration of Endodontically Treated Teeth.

Objective The aim of this systematic review was to provide an overview of available scientific evidence regarding the comparative efficacy of computer-aided design (CAD) and computer-aided manufacturing (CAM) glass fiber posts with prefabricated and metal cast posts for the restoration of endodontically treated teeth (ETT). Methods This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic and manual searches were performed using the PubMed, SciELO, Cochrane, ScienceDirect, Web of Science, and EBSCO databases. The reference lists of the selected papers were reviewed to identify relevant papers. There were no year restrictions, and eligible studies were those in English publications and describing in vitro studies evaluating intraradicular retainers (IRs) for (i) fracture resistance, (ii) bond strength, (iii) adaptation, and (iv) cement layer thickness. Literature reviews, systematic reviews, meta-analyses, case reports, in vitro studies with <8 specimens, and noncomparative trials involving prefabricated or metal cast posts were excluded. The authors of this review independently screened the search results, extracted data, and assessed the risk of bias. Results No significant differences were found in fracture resistance between prefabricated and CAD/CAM glass fiber posts or between CAD/CAM glass fiber and metal cast posts, although the latter demonstrated higher fracture resistance than the prefabricated glass fiber posts. Restoration with a full crown was not necessary to increase the fracture resistance in the presence of the ferrule effect. CAD/CAM glass fiber and metal cast posts had higher bond strength, lower nanoleakage, and better adaptation to the root canal. Conclusions Despite the heterogeneity of methodologies and results reported, the results of these studies indicated that the CAD/CAM glass fiber and metal cast posts showed greater efficacy in terms of fracture resistance, retention, and adaptation, compared to prefabricated glass fiber posts.

Fracture resistance of thin wall endodontically treated teeth without ferrules restored with various techniques.

To evaluate the fracture resistance and failure characteristics of simulated thin wall endodontically treated teeth without ferrules restored with various techniques. Forty-eight human mandibular single-root canal premolars were decoronated and endodontically treated. The 1 mm thick remaining root canal dentin was prepared. The roots were randomly divided into four groups of 12 roots according to the following post and core reconstruction techniques: direct resin composite post and core (CP), multiple fiber posts and resin composite core (FP), CAD/CAM anatomical post and core (AP), and metal cast post and core (MP). Full metal crowns were cemented to the cores. All specimens were subjected to thermocycling for 5000 cycles and submitted to axial compression until failure at a 45°angle using a universal testing machine. The failures were classified into one of the followings: post and/or core fractures, root fractures, and root fractures combined with post and/or core fractures. Average failure loads of groups CP, FP, AP, and MP were 360.0, 655.2, 402.7, and 856.1N, respectively. MP provided the highest failure load, which was significantly higher than those of the other groups (p < 0.05). FP was second, being inferior to MP with a significance level of p=0.039. CP exhibited the least failure load, and it was not significantly different from the AP group (p > 0.05). Root fractures were the major failure mode for most of the specimens except the CP group, in which composite fractures at the cervical level were commonly observed. Metal cast post and core provided the highest fracture resistance for reconstruction of a thin wall in endodontically treated teeth without ferrules, followed by multiple fiber posts and resin composite core. The milled anatomical post and core and a direct resin composite post and core provided significantly lower fracture resistance. Metal cast posts and core and multiple fiber posts with resin composite core techniques were effective for restoring severely compromised endodontically treated teeth.

Retention of Cast Posts Cemented with Two Commonly Used Conventional and Two Resin Cements and the Mode of Root Fracture Following Their Removal.

Objectives: This study aimed to compare the retention of cast posts cemented with four types of cements and assess the mode of root fracture following their removal. Materials and Methods: In this in vitro, experimental study, 48 upper central incisors were randomly divided into 4 groups of 12, and were endodontically treated. The fabricated cast posts in each group were cemented with zinc phosphate (Masterdent), glass ionomer (GI; Meron), Meta resin cement, and Panavia SA resin cement. A device was customized for post removal by a universal testing machine similar to WAM X pliers. The retention of cemented posts was measured by the pull-out test in a universal testing machine. Next, the teeth were macroscopically and microscopically inspected regarding the occurrence and sites of catastrophic fracture, cracks, or craze lines. Quantitative and qualitative data were analyzed by ANOVA, and Chi-square test, respectively (P<0.05). Results: ANOVA showed a significant difference in the mean retention of cements (P<0.001). Panavia provided the highest retention (278.6±34.9 N) followed by zinc phosphate (221.9±28.88 N), GI (161.3±60.7 N), and Meta (140.4±66.54 N). There was no significant difference between the groups regarding the pattern of root fracture (P=0.39). However, site and extent of fractures were significantly different among the groups (P<0.05). Conclusion: The conventional cements provided optimal retention and caused less root damage after post removal. Thus, cements providing adequate retention and allowing easier post removal are recommended for use in endodontically treated teeth with a possibility of requiring retreatment.