A new classification system for the restoration of root filled teeth

Principles guiding the restoration of the root-filled tooth

Endodontic treatment is usually required because of significant coronal disease or traumatic tissue loss. The restoration of the subsequently endodontically treated tooth is also complicated by the reduction in its structural strength consequent to accessing the pulp chamber and the removal of radicular dentine during root canal instrumentation, alongside some alteration of dentinal properties during disinfection by chemical agents, prior to obturation. A loss of proprioceptive feedback, which may lead to increased loading, can place further stress on the already very compromised structure. This article considers the principles of restoring endodontically treated teeth: assessing restorability, providing a coronal seal to prevent reinfection, and gaining retention for a core where necessary, to restore aesthetics and function. Consideration is given to the patient and material factors that influence the decision to restore the treated tooth using direct or indirect restorations. Specific attention is given to anterior or posterior teeth and the various materials which may be used in their overall restoration with their associated, probable, longevity.

Load-Bearing Capacity of Incisors Restored Using Fiber-Reinforced Composite Post-Core Systems

Objectives: This study aimed to analyze the load-bearing performance of upper incisors and evaluate the curing of the luting polymer composite at various depths within the canal. Methods: A total of one hundred maxillary central incisors (10 groups, n = 10/group) were subjected to various restorative techniques. Approach A used Gradia Core for post-core and crown; Approach B employed prefabricated fiber posts (4 mm or 8 mm) with Gradia for luting and core build-up; Approach C used short-fiber composite (everX Flow) for post-core build-up; and Approach D used fiber posts with everX Flow for luting and core build-up. Restorations underwent cyclic fatigue (40,000 cycles at 95 N) and quasi-static fracture testing. Surface hardness of luting polymer composites was also measured. Results: Data showed that restorations with additional fiber posts (Approaches B and D) had significantly higher load-bearing capacity (p < 0.05), while post material and length had no significant impact (p > 0.05). Short-fiber composite as luting and core material (Approach D) enhanced load-bearing performance compared to Gradia-based restorations (Approach B, p < 0.05). Conclusions: The use of short-fiber composite as both the post luting and core material in restoring compromised incisors, along with a conventional fiber post, demonstrated favorable results in terms of load-bearing capacity.

Fracture resistance and failure modes of endodontically-treated permanent teeth restored with Ribbond posts vs other post systems: a systematic review and meta-analysis of in vitro studies

Objectives

This systematic review aimed to investigate the fracture resistance and mode of failure of endodontically-treated permanent teeth restored with Ribbond posts (Ribbond, Inc.) compared with endodontically-treated permanent teeth restored with other post systems.

Methods

A comprehensive, systematic literature search was carried out using several electronic databases: MEDLINE/PubMed, Google Scholar, and Cochrane Library. Two separate researchers were appointed to identify the studies meeting the eligibility criteria, and to perform the data extraction, risk of bias, and quality assessment.

Results

Twelve studies were included in the quantitative analysis. Meta-analysis was performed with 11 of the 12 included articles. The meta-analysis showed that Ribbond posts have a fracture strength less than prefabricated metal posts, cast metal posts, and prefabricated fiber posts and greater than custom e-glass fiber posts. Mode of failure analysis revealed that Ribbond posts have the most favorable non-catastrophic fractures.

Conclusions

Although Ribbond posts have lower fracture resistance, their favorable mode of failure makes them potentially the most biomimetic post system.

Clinical Outcomes and Complication Rates of Endodontically Treated Teeth with Fixed Dental Prostheses: A Retrospective Study

Background/Objectives: Endodontically treated teeth (ETT) often have significant structural damage and require multiple reinforcing methods during the reconstruction process. The aim of this study was to evaluate the complication rates of ETT with and without a post. Methods: The study investigated various clinical factors, including technical complications as well as biological complications. All patients who had previously received fixed dental prostheses (FDPs) were subjected to clinical and radiographical examinations during their follow-up visits. Clinical and radiographic assessments were performed to determine the cumulative survival rate, and life table survival analyses of FDPs in the presence of complications were performed. Results: A total of 287 ETT were evaluated in this study, in which 219 were placed in females and 68 in males, with an average follow-up time of 82.4 months. There were no significant differences between ETT with a post and ETT without a post regarding the complication rates. The complication rates of the FDPs without a post revealed a survival rate of 58% after 5 years, 44% after 10 years, and 29% after 15 years. On the other hand, the complication rates of the FDPs with a post revealed survival rates of 50%, 30%, and 21% after 5, 10, and 15 years, respectively. The Kaplan-Meier survival analysis showed no significant differences in the complication rates, regardless of the existing of the posts (p = 0.830). Conclusions: ETT restored with FDPs with or without a post can show similar complication rates in a long-term evaluation. Furthermore, the types of final restoration may not have an effect on the complication rate with ETT.

Comparative evaluation of incorporation of ferrule in premolars endocrown designs to check any alterations in their fracture resistance: A pilot study

Introduction

Endocrown preparation of endodontically treated teeth as final restoration has been extensively studied for different teeth. Bindl et al. questioned the application of endocrowns for premolars due to the pulp chamber space's smaller dimensions, which diminish bonding surface area. The addition of ferrule into the endocrown preparations of premolars has not been extensively studied.

Aims and Study Design

Comparative evaluation of incorporation of the ferrule in premolars endocrown designs to check any alterations in their fracture resistance.

Materials and Methods

The sample consisted of 40 maxillary first premolars without cracks or caries, extracted for orthodontic or periodontal purposes. The teeth were individually mounted with cold-cure acrylic resin. Group A: Composite endocrown without ferrule and Group B: Composite endocrown with ferrule. An endocrown former was prepared with elastomeric polyvinyl siloxane material (GC Exaclear). Endocrowns were then prepared with dual-cure core build-up composite-Core-x flow (Dentsply Maillefer, Switzerland) using the endocrown former so that morphologically, they all were almost identical. Endocrowns are cemented by dual-cure resin cement following manufacturer instructions. The fracture resistance of endocrowns with and without ferrule was evaluated and compared.

Results and Observations

The data were tabulated in Microsoft Excel and analyzed with SPSS version 24 software. The variables were presented with mean, standard deviation, and independent t-test. The P ≤ 0.05 is considered statistically significant. Group B (with ferrule) showed higher fracture resistance (622.06 N) than Group A (537.59 N) (without ferrule). Independent t-test showed that the difference was statistically significant (P = 0.008).

Conclusion

Comparing the failure load findings, it could be concluded that ferrule-containing endocrown needed greater loads than ordinary endocrown restorations for failure.

Influence of size-anatomy of the maxillary central incisor on the biomechanical performance of post-and-core restoration with different ferrule heights

PURPOSE

The study aims to investigate the influence of the ferrule effect and types of posts on the stress distribution in three morphological types of the maxillary central incisor.

MATERIALS AND METHODS

Nine models were created for 3 maxillary central incisor morphology types: "Fat" type - crown 12.5 mm, root 13 mm, and buccolingual cervical diameter 7.5 mm, "Medium" type - crown 11 mm, root 14 mm, and buccolingual cervical diameter 6.5 mm, and "Slim" type - crown 9.5 mm, root 15 mm, and buccolingual cervical diameter 5.5 mm. Each model received an anatomical castable post-and-core or glass-fiber post with resin composite core and three ferrule heights (nonexistent, 1 mm, and 2 mm). Then, a load of 14 N was applied at the cingulum with a 45° slope to the long axis of the tooth. The Maximum Principal Stress and the Minimum Principal Stress were calculated in the root dentin, crown, and core.

RESULTS

Higher tensile and compression stress values were observed in root dentin using the metallic post compared to the fiber post, being higher in the slim type maxillary central incisor than in the medium and fat types. Concerning the three anatomical types of maxillary central incisors, the slim type without ferrule height in mm presented the highest tensile stress in the dentin, for both types of metal and fiber posts.

CONCLUSION

Post system and tooth morphology were able to modify the biomechanical response of restored endodontically-treated incisors, showing the importance of personalized dental treatment for each case.

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).

Forced orthodontic extrusion for an apparently hopeless anterior tooth by using a simplified approach

When restoring severely compromised teeth, respecting the supracrestal tissue attachment and retaining the most coronal and radicular tooth structure is essential to achieving a sufficient ferrule. Forced orthodontic extrusion is a minimally invasive method that allows hard- and soft-tissue conservation. This article describes the treatment of a severely damaged maxillary central incisor that was managed by using a simplified orthodontic extrusion method with intracoronal elastic and metal ligatures applied through a palatal bar and followed by the biologically oriented preparation technique (BOPT). This orthodontic procedure reduces a forward clockwise advance during vertical extrusion, thus maintaining the buccal bone plate.

Mechanical Properties and Clinical Success of Intracanal Posts in Primary Maxillary Anterior Teeth: A Systematic Review and Meta-analysis

Background

Intracanal posts are commonly used to restore lost permanent/primary tooth structure and the smile of the patient.

Aim

This systematic review aims to evaluate the clinical success of intracanal posts used in primary maxillary anterior teeth and compare their mechanical properties.

Methods

An extensive literature search was performed using Medline via PubMed, Embase via embase.com, LILACS, CINAHL via EBSCO, Cochrane Oral Health Group Specialized Register, Scopus, and Web of Science until December 2021 and was updated till December 2022. In vivo and in vitro studies in the English language that assessed clinical success and mechanical properties were included. Distiller SR software was used for everything from title screening to data extraction.

Results

A total of 30 studies were analyzed, including 11 in vivo and 19 in vitro studies. Four studies were included in a meta-analysis, and all 30 studies qualified for qualitative analysis. The meta-analysis showed that fiber posts are clinically superior to composite resin posts (CRPs) (p = 0.02). No significant difference was observed between the fracture resistance of CRPs and no posts (p = 0.73). Most of the included studies showed a high risk of bias.

Conclusion

Conclusive evidence about the effectiveness of various intracanal posts cannot be established. This is due to the limited number of clinical trials and included studies of low to moderate quality with a high risk of bias. To validate the use of posts in primary maxillary anterior teeth, further research, including randomized controlled trials (RCTs) of higher quality, is required.

Clinical significance

The use of intracanal posts in primary teeth is a commonly used treatment modality among pediatric dentists. However, the quality of the evidence to support its use is low. This systematic review provides a comprehensive summary of the current literature and highlights the need for further research. Results were interpreted with caution, as the evidence supporting the use of intracanal posts in primary teeth is limited.

How to cite this article

Shanmugam Y, Raghu A, Muthu MS, et al. Mechanical Properties and Clinical Success of Intracanal Posts in Primary Maxillary Anterior Teeth: A Systematic Review and Meta-analysis. Int J Clin Pediatr Dent 2023;16(S-3):S293-S305.

Cumulative 10-year performance of endodontically treated teeth with prosthetic restorations of base metal alloy double crowns with friction pins-a retrospective study

OBJECTIVES

This 120-month follow-up study aimed to investigate the complication rate of abutment teeth after endodontic pretreatment with base metal alloy double crowns with friction pins.

MATERIALS AND METHODS

A total of 158 participants (n = 71, 44.9% women) aged 62.5 ± 12.7 years with 182 prostheses on 520 abutment teeth (n = 459, 88.3% vital) were retrospectively analyzed between 2006 and 2022. Of the endodontically treated abutment teeth, 6.9% (n = 36) were additionally treated with post and core reconstructions. Cumulative complication rates were calculated using the Kaplan-Meier estimator and log-rank test. In addition, Cox regression analysis was performed.

RESULTS

The cumulative complication rate at 120 months for the entire set of abutment teeth was 39.6% (confidence interval [CI]: 33.0-46.2). Endodontically treated abutment teeth (33.8%; CI: 19.6-48.0) were found to have a significantly higher cumulative fracture rate than vital teeth (19.9%; CI: 13.9-25.9, p < 0.001). Endodontically treated teeth restored with post and core reconstructions (30.4%; CI: 13.2-47.6) showed a nonsignificant lower cumulative fracture rate than that of teeth with root fillings only (41.6%; CI: 16.4-66.8, p = 0.463).

CONCLUSIONS

Higher 120-month cumulative fracture rates were observed in endodontically treated teeth. Comparable performance was observed in teeth with post and core reconstructions compared to teeth with root fillings only.

CLINICAL RELEVANCE

If endodontically treated teeth are used as abutments for double crowns, the risk of complications from these teeth should be considered when planning treatment and communicating with the patient.

Effect of degree of conversion on the surface properties of polymerized resin cements used for luting glass fiber posts

STATEMENT OF PROBLEM

Lack of conversion of resin cements for luting glass fiber posts in deeper levels of the root canal may compromise clinical performance.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of the degree of conversion on the surface properties of dual-polymerized resin cements used for cemented glass fiber posts according to the root level.

MATERIAL AND METHODS

Fifty maxillary central incisor teeth were endodontically treated, and glass fiber posts were cemented using the following systems: self-adhesive dual-polymerized resin luting cement (RelyX U200) and dual-polymerizing flowable core and a post luting system (Rebilda DC) with a self-etching adhesive (Futurabond DC). The degree of conversion was determined via attenuated total reflectance and Fourier transform infrared spectroscopy, and surface microhardness and cement film thickness were measured. The intraradicular fit was evaluated with microscopy. All tests were performed in the coronal, middle, and apical third of the root canal. Statistical analysis was done with ANOVA and the multiple comparison Tukey test (α=.05).

RESULTS

The degree of conversion was higher in the coronal third using Rebilda DC (65.3 ±4.8%) than RelyX U200 (38.7 ±5.3%) (P<.05); on both resin cements, these values decreased from the coronal to the apical third (30.9 ±3.7%, 61.9 ±8.7%, respectively). The cement film thickness was higher for RelyX U200 in the 3 thirds than for Rebilda DC; significant differences (P<.05) were recorded in both cementing systems in the coronal and apical thirds. In the middle third, no significant differences were observed (P>.05). The mean surface microhardness values increased in the coronal thirds and decreased with increasing root canal depth. The marginal seal in the coronal thirds and the intraradicular fit in the middle thirds showed closer adaptation; however, some tags were observed in the interface resin cement and radicular dentin. Gap and tag formations were observed in the apical third.

CONCLUSIONS

Depending on the root canal third, the surface properties of dual-polymerized resin cements are influenced by the degree of conversion.

Porcelain Veneers in Vital vs. Non-Vital Teeth: A Retrospective Clinical Evaluation

Nowadays, the ceramic veneer approach can be considered more predictable than direct composite veneer. To date, there is a lack of studies comparing the clinical performance of anterior veneers cemented on vital teeth (VT) and non-vital teeth (NVT). This longitudinal clinical study investigated the performance of ceramic veneers in VT or anterior NVT. A total of 55 patients were evaluated in the study. Two groups were defined based on the vitality status of the teeth (93 teeth-vital and 61 teeth-non-vital). The United States Public Health Service (USPHS) criteria were used to assess the clinical status. The data were evaluated statistically with the Mann-Whitney U test. All restorations were considered acceptable, and only one veneer in VT failed for the criteria of secondary caries. There were no statistically significant differences in any of the criteria evaluated (p ≤ 0.671). The ceramic veneers evaluated showed a satisfactory clinical performance both in VT and NVT.

Push-Out Bond Strength of Endodontic Posts Cemented to Extracted Teeth: An In-Vitro Evaluation

(1) Background: An ideal bond strength between endodontic posts and root canal dentin is essential for optimal retention and good prognosis. This study aimed to evaluate the push-out bond strength (PBS) of prefabricated fiber and metal posts, luted with resin cement to natural dentin. (2) Methods: Extracted premolars with similar root dimensions were assigned into two groups of 30 each for the metal and fiber posts. Teeth were mounted in acrylic blocks exposing 2 mm of the coronal root. Teeth were subjected to endodontic treatment and post-space preparations. Two groups were further subdivided into three sub-groups (n = 10) according to the size of the posts (# 4, 5 and 6). Posts were cemented with resin cement. Specimens were sectioned into 4 mm slices and subjected to the PBS test. (3) Results: The mean PBS was similar for the metal and fiber posts bonded with resin cement, showing a statistically significant result. An increase in post size increased the bond strength initially, but a further increase in size did not show any marked difference. A total of 71.66% of tested specimens failed with the adhesive failure mode. (4) Conclusions: Metal posts showed slightly higher retention compared to the fiber posts, although the p-value was similar for both types. An increase in the size of posts showed increased retention. The most common mode of failure was adhesive failure between cement and dentin.

Post Placement and Restoration of Endodontically Treated Canines: A Finite Element Analysis Study

The purpose of this study was to show the improved outcomes of restoring endodontically treated teeth with fiberglass posts compared to restorations using metal posts. In our study, we used the Finite Element Method (FEM), which is based on the principle that a physical model that supports a given load distributes the stress throughout its volume. We sought to assess what stress results in a tooth when it is restored using a fiberglass post compared to restoration using a metal post. The finite element analysis showed that a system consisting of a tooth with a fiberglass post is more stable in terms of the maximum stress than a system consisting of a tooth with a metal post. The maximum displacements and deformations were obtained in the case of a canine restored with a fiberglass post, which showed that this system had a high elasticity, therefore, higher strength than a canine restored with a metal post, which had high rigidity.

In Vitro Evaluation of the Strength of Dentin Replacement in Complex Posterior Tooth Restoration

Due to the increasing interest in direct restoration, there is a need to address the shortcomings of these restorations, mainly by increasing the longevity of complex direct restorations. The present study aimed to evaluate the tensile strength differences in the complex restoration of posterior teeth with dentin replacement constructed by fiber and non-fiber materials. The samples were extracted from the mandibular permanent-molar and prepared using a complex cavity. The cavity was subsequently restored with the centripetal incremental technique using a nano-fill composite and different base materials, namely fiber dentin replacement, non-fiber dentin replacement, and flowable composite. The universal testing machine was used to consider the tensile strength and the fracture patterns were assessed using stereomicroscopy, followed by Scanning Electron Microscopy (SEM) examination. The data were statistically analyzed using the one-way ANOVA test. No significant differences were noted in the tensile strength of the three base materials. By using stereomicroscopy and SEM, the adhesive fracture patterns were observed more clearly in the cavities with fiber-based dentin replacement, whereas mixed fracture patterns were evident in cavities with non-fiber dentin replacement and flowable composite bases. The results indicated that the addition of fiber in dentin replacement did not affect the tensile strength in the complex restoration. Therefore, dentin replacement of both fiber and non-fiber materials is applicable as a base material for complex restoration of the posterior tooth.

Accuracy of Digital Impression Taking with Intraoral Scanners and Fabrication of CAD/CAM Posts and Cores in a Fully Digital Workflow

Current intraoral scanners (IOS) enable direct impression taking for computer-aided de-sign/computer-aided manufacturing (CAD/CAM) posts and cores (P+C) with subsequent milling out of monolithic materials. The aim of this in vitro study was to systematically investigate the accuracy of CAD/CAM-P+C in a fully digital workflow, considering different IOS impression methods (Primescan (PRI), Trios4 without (TRI) and with scanpost (TRI+SP)) (Part A), and CAD/CAM milling of zirconium dioxid (ZIR) and resin composite (COM)-P+C (Part B). Five human models were developed in this study. Micro-CT imaging was used as a reference (REF). For Part A, the models were scanned 12 times for each impression method. Then, IOS datasets (n = 180) were superimposed with REF, and scan accuracy was determined using 3D software (GOMInspect). For Part B, one CAD/CAM-P+C (n = 30) was milled for each model, impression method, and material. The triple-scan method was applied using an industrial scanner (ATOS) to determine the accuracy of the fit. Statistical analysis was performed using analysis of variance (ANOVA, p < 0.05). Part A showed for PRI significantly lower accuracy than TRI and TRI+SP (p < 0.05). The data of Part B revealed significantly higher accuracy for ZIR than for COM (p < 0.05). Within the limitations of this study, CAD/CAM-P+C of the ZIR can be recommended for fabrication in a fully digital workflow regarding the accuracy of fit.

Flexural Strength of Dental Fiber Composite Post Manufactured with a Novel Approach

Thermoplastic resin fiber composites have an easy fabrication process, good mechanical properties, and compatible stiffness to tooth dentin. However, they have not yet attracted much interest in the field of dentistry. The current study was carried out to test a new proposed approach to manufacture a fiber reinforced composite endodontic post and evaluate its flexural strength through a two-point inclined loading test. The proposed fiber post manufacture approach depends upon a braiding technique of the glass fibers’ (GF) reinforcing component with thermoplastic polypropylene (PP) resin fibers that will later represent the resin matrix after thermal melting. Posts were made of different core (70%) and sheath (30%) construction (PP/GF ratios) using three different GF types and seizing pre-treatment to both fiber types. Two-point inclined loading test at 45 °C applied force angle was used to test the posts’ flexural strength. Fiber posts (1.6 mm in diameter) with pure GF (de-sized starch E-GF and pre-silanized S-GF) core, and sheath construction with higher PP/GF ratios, showed the significantly highest two-point bending strength (56.67 ± 4.89 and 53.96 ± 1.81 MPa, respectively), among experimental posts groups (except for the commercial control posts). However, posts with PP core type showed the lowest values (21.59 ± 1.86 and 16.54 ± 1.94 MPa for de-sized and E-glass sheath fibers, respectively). Based on these findings, the proposed approach was reliable in producing fiber-reinforced composite post with the desired dimensions and fiber distribution. Post construction with a pure GF core and higher PP/GF ratio showed considerably higher flexural strength and GF volume fraction comparable to commercial available post types.

Fracture resistance of root canal-treated molars restored with ceramic overlays with/without different resin composite base materials: an in vitro study

The objective of the study was to evaluate the effect of different restorative protocols on fracture resistance of root canal-treated molars. 48 mandibular first molars were used and divided into six groups (n = 8); G1 (negative control): teeth kept intact. G2 (positive control): teeth had root canal treatment and standard MOD cavity preparations but kept unrestored. G3: prepared as G2 and directly restored with VitaEnamic ceramic overlays (CO). G4: as G3, but the pulp chamber was restored first with smart dental restorative (SureFil SDR flow = SDR) bulk-fill flowable composite base. G5: as G3, but the pulp chamber was restored first with SonicFill (SF) bulk-fill composite base. G6: as G3, but the pulp chamber was restored first with a fiber-reinforced composite (FRC) base. All samples were subjected to thermocycling between 5 °C and 55 °C in a water bath for a total of 2000 cycles with 10 s dwell time. Then specimens were individually mounted on a computer-controlled testing machine with a load cell of 5 kN, and the maximum load to produce fracture (N) was recorded. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (P = 0.05). There was a significant difference between the groups (P < 0.001). Teeth restored with FRC and ceramic overlays had the highest load-bearing capacity. Pulp chamber restoration with either FRC or SDR before ceramic overlay fabrication provided significantly better tooth reinforcement than ceramic overlay alone (P < 0.001). Fracture modes were analyzed to determine the type of fracture as repairable or catastrophic, where FRC + CO and SDR + CO groups had favorable fracture modes that were mostly repairable. When restoring root canal-treated molars with overlays, the pulp chamber should be sealed with either FRC or SDR to ensure the best possible fracture resistance. The clinical relevance of the study is that a new simple restorative protocol is presented to enhance the survival of root canal-treated molars using ceramic overlays.

Taurodontism—Prevalence, Extent, and Clinical Challenge in Ashkelon, Israel—A Retrospective Study

Taurodontism, a known morpho-anatomic variation in the shape of teeth, has already attracted substantial attention. The aim of this study is to contribute to this by discussing its direct impact on the dental practitioner via an evaluation of the prevalence of taurodontism in molars in Ashkelon, Israel. This retrospective study analyzed panoramic radiographs of 624 patients (330 males, 294 females), aged of 9–29 years—2849; first and second permanent molars were screened. Objective measurements and variables were used and analyzed using statistical SPSS version 27 (IBM, Chicago, IL, USA). Taurodontism was observed in 33.6% of the patients and was more prevalent among females (53% vs. 47%) and in maxillary molars compared to mandibular molars (57% vs. 43%). The overall prevalence of hypotaurodontism, mesotaurodontism, and hypertaurodontism was 10.8%, 0.5%, and 0.2%, respectively. No statistical difference between right and left sides was discovered, however, taurodont teeth in the upper left side exhibited the highest frequency, while the lower left side had the least. The highest occurrence of hypotaurodontism was on the upper right second molar followed by upper left first and second molars. The clinical challenge posed in endodontic, orthodontic, and restorative dentistry is discussed, and suitable alternative approaches are proposed for dental practitioners.

Effect of Luting Cement Film Thickness on the Pull-Out Bond Strength of Endodontic Post Systems

Optimal bond strength between the prefabricated post/dowel to the surrounding dentin is essential. The present study aimed to analyze and compare the effect of three different cement film thicknesses on the pull-out bond strength of three different prefabricated post systems. Extracted natural teeth (N = 90) with similar root dimensions were acquired. Teeth were mounted in resin blocks, endodontically treated, sectioned at cemento-enamel junction, divided into three groups (A: Parapost Fiber Lux plus; B: 3M ESPE Relyx fiber post; and C: Parapost XP), and stored. Uniform post spaces were prepared for the groups (A and C: Length = 8 mm, Width = 1.5 mm; B: Length = 8 mm, Width = 1.6 mm). Each group (N = 30) was further subdivided into three subgroups (n = 10) based on the size (4, 5, and 6) of the post and cemented with resin cement (MultiLink-N, Ivoclar Vivadent). After thermocycling, the specimens were subjected to a pull-out test using a universal testing machine, and tensile force was recorded (MPa). Digital microscopic evaluations were performed for modes of failure. ANOVA and Tukey-HSD tests were used for statistics. Significant differences were observed for each tested material (p = 0.000). The lowest and highest bond strength values were recorded for Group C (Titanium post) and Group A (000), respectively. Multiple comparisons showed significance (p < 0.05) among all the groups, except for space 1 and space 2 (p = 0.316) for Group A. Most of the failures occurred within the cement-dentin and post-cement interface (Adhesive failures, 73.5%). An increase in the luting cement film thickness results in the decrease in pull-out bond strength of prefabricated posts luted with resin cement, irrespective of the type/material/shape of the post. The serrated fiber posts showed the highest pull-out bond strength compared to the smooth surfaced fiber posts or serrated metal posts. Increased pull-out bond strengths were observed when appropriate post space was created with the same sized drill as the post size.

A laboratory study to assess the physical, mechanical, and 3-D structural properties of nano-apatite grafted glass fibre-based endodontic posts

AIM

To fabricate and characterize nano-hydroxyapatite (nHA) grafted and non-grafted glass fibre-based endodontic posts.

METHODOLOGY

Experimental glass fibre posts were fabricated using silanized nHA grafted (ex-HA) and non-grafted glass fibre (ex-P) reinforced resins. The structural analysis and morphological patterns were analysed with Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. EverStick^® glass fibre posts (eS) were used as a control group. The degree of conversion, flexural strength, and flexural modulus was investigated and the fractured structure was evaluated with a scanning electron microscope. Root canals were prepared in human extracted teeth restored with experimental and control posts. The push-out bond strength was evaluated with radicular dentine at days 7, 30, and 90, and the presence of voids at the interface were measured at day 1, 7, 30, and 90 with micro-computed tomography. The Shapiro-Wilk test and one-way ANOVA post-hoc Tukey's test were performed. The level of significance was set at 0.05.

RESULTS

The SEM and FTIR confirmed the presence of a silane-coupling agent on the glass fibres. The ex-HA post had a significantly lower degree of conversion compared to the ex-P post (p = .0008), but a significantly higher conversion than the eS post (p = .0014). The maximum flexural strength value was obtained with the ex-HA post with an insignificant difference (p = .366) compared to ex-P post and a significant difference (p = .029) compared to the eS post. The flexural modulus of ex-HA, ex-P, and eS posts were significantly different (p = .037). Similarly, the ex-HA post had a significantly higher push-out bond strength at days 7 and 30 (p = .037) compared to the ex-P and eS posts. The volume of voids had a nonlinear behaviour amongst the groups with no significant difference between the posts.

CONCLUSION

The fabrication of the experimental posts was successful and the ex-HA post had greater flexural strength and push-out bond strength compared to the ex-P post. The degree of conversion of the ex-HA post was lower than the ex-P and eS posts. The volume of voids of ex-HA and ex-P posts was lower than that of eS posts.

European Society of Endodontology position statement: The restoration of root filled teeth

This position statement on the restoration of root filled teeth represents the consensus of an expert committee, convened by the European Society of Endodontology (ESE). Current clinical and scientific evidence, as well as the expertise of the committee, have been used to develop this statement. The aim is to provide clinicians with evidence-based principles for decision-making on the choice of restoration following the completion of root canal treatment. By discussing the evidence in relation to key topics regarding post-endodontic restoration, a series of clinical recommendations are made. The scientific basis of the recommendations made in this paper can be found in a recently published review article (Bhuva et al. 2021, International Endodontic Journal, https://doi.org/10.1111/iej.13438). It is the intention of the committee to update this statement as further evidence emerges.

Characterization of Experimental Short-Fiber-Reinforced Dual-Cure Core Build-Up Resin Composites

As a core build-up material, dual-cured (DC) resin-based composites are becoming popular. The aim of this research was to investigate specific physical and handling properties of new experimental short-fiber-reinforced DC resin composites (SFRCs) in comparison to different commercial, conventional DC materials (e.g., Gradia Core, Rebilda DC, LuxaCore Z, and Visalys^® CemCore). Degree of monomer conversion (DC%) was determined by FTIR-spectrometry using either self- or light-curing mode. The flexural strength, modulus, and fracture toughness were calculated through a three-point bending setup. Viscosity was analyzed at room (22 °C) and mouth (35 °C) temperatures with a rotating disk rheometer. The surface microstructure of each resin composite was examined with scanning electron microscopy (SEM). Data were statistically analyzed with analysis of variance ANOVA (p = 0.05). The curing mode showed significant (p < 0.05) effect on the DC% and flexural properties of tested DC resin composites and differences were material dependent. SFRC exhibited the highest fracture toughness (2.3 MPa m^1/2) values and LuxaCore showed the lowest values (1 MPa m^1/2) among the tested materials (p < 0.05). After light curing, Gradia Core and SFRCs showed the highest flexural properties (p < 0.05), while the other resin composites had comparable values. The novel DC short-fiber-reinforced core build-up resin composite demonstrated super fracture toughness compared to the tested DC conventional resin composites.

Effect of Composite Core Materials on Fracture Resistance of Endodontically Treated Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies

Various material properties are involved in the success of endodontically treated restorations. At present, restorative composites are commonly employed as core build-up materials. This study aimed to systematically review the literature to assess the effect of using composite core materials on the in vitro fracture of endodontically treated teeth. Two different reviewers screened the literature, up to June 2021, in five distinct electronic databases: PubMed (MedLine), Scopus, Scielo, ISI Web of Science, and EMBASE. Only in vitro studies reporting the effect of the use of composite core materials on the fracture resistance of endodontically treated teeth were included. A meta-analysis was carried out using a software program (Review Manager v5.4.1; The Cochrane Collaboration, Copenhagen, Denmark). The risk of bias in each study was assessed following the parameters of another systematic review. A total of 5016 relevant papers were retrieved from all databases. After assessing the title and abstract, five publications remained for qualitative analysis. From these, only three studies remained for meta-analysis. The fracture strength of endodontically treated teeth where a core build-up composite was used was statistically significantly higher than the control (p = 0.04). Most of the analyses showed a high heterogenicity. The in vitro evidence suggests that the composite core build-up with higher filler content tended to improve the fracture resistance of the endodontically treated teeth, in comparison with conventional composite resins. This research received no external funding. Considering that this systematic review was only carried out on in vitro papers, registration was not performed. Furthermore, there were no identified clinical studies assessing core build-up materials; therefore, more well-designed research on these materials is needed.

One-Year Clinical Aging of Low Stress Bulk-Fill Flowable Composite in Class II Restorations: A Case Report and Literature Review

Bulk-fill flowable composites provide functional and aesthetic restorations while eliminating incremental composite layering and saving time. The degradation of the adhesive interface with subsequent gap formation is a concern when adhesively luted restorations are placed. Moreover, the number of adhesive interface failures increases when they are exposed to long-term water storage. The aim of the present study was to evaluate the morphological characteristics of the tooth-composite interface in class II cavities restored with a low stress bulk-fill flowable composite after aging in an oral environment. We describe a case of a patient with class II cavities in four premolars restored with a low stress bulk-fill flowable composite Surefil SDR (Dentsply DeTrey GmbH, Konstanz, Germany). The occlusal part was restored with nano-hybrid resin composite Ceram X Mono (Dentsply DeTrey GmbH). After one year of clinical function, the teeth were extracted and examined in a scanning electron microscope (SEM). It can be concluded that the application of bulk-fill covered with conventional composite seems to provide the homogeneous and stable bond to tooth structure after one year of aging in an oral environment. However, some defects within the dentin-resin composite interface were observed.

Influence of Post-Core and Crown Type on the Fracture Resistance of Incisors Submitted to Quasistatic Loading

The aim of this paper was to evaluate the fracture resistance and failure type of maxillary incisor teeth, rebuilt with various types of post-core restorations and full crowns made of either direct conventional particulate filler composite (PFC, G-aenial Anterior, GC, Tokyo, Japan) or indirect CAD/CAM restorations (composite Cerasmart 270 and glass ceramic LiSi Block from GC). One hundred (n = 10/group) central incisors were cut and divided into 10 experimental groups restored with different approaches. In approach A, teeth were restored with a core build-up composite (Gradia Core, GC) for a core and full crown of PFC. Approach B had teeth restored using composite core and prefabricated fiber posts, and a complete crown of either PFC or CAD/CAM. Approach C contained teeth restored with a core of short fiber-reinforced composite (everX Flow, GC) and prefabricated fiber posts, and a complete crown of either PFC or CAD/CAM. In approach D, the teeth had a core of short fiber-reinforced composite only, and a complete crown of either PFC or CAD/CAM restorations. The root canals were prepared, and when posts were used, they were luted with either a dual-cure resin cement (LinkForce, GC) or everX Flow. As the control, sound teeth (n = 10) were used. Restorations were quasi-statically loaded until fracture. Failure type was visually investigated. The interface between the fiber post and luting cement was investigated using SEM, before and after completion of the loading test. The data were analyzed by analysis of variance (p = 0.05) followed by Tukey's test. None of the restorative approaches restored the fracture load strength of intact teeth (p < 0.05). Restorations with additional fiber posts (Approaches B and C) had higher load-bearing capacity (p < 0.05) than restorations without fiber posts (Approaches A and D). Restorations that had short fiber-reinforced composite cores with or without fiber posts presented more repairable failures. Using short fiber-reinforced composite as post-luting and core build-up material with conventional fiber posts proved to be a promising method to strengthen severely damaged incisors.

Fatigue failure of anterior teeth without ferrule restored with individualized fiber-reinforced post-core foundations

OBJECTIVES

The aim was to explore the survival of extensively damaged anterior teeth without ferrule restored with different fiber-reinforced composite (FRC) post-core foundations and composite crowns.

MATERIALS AND METHODS

Sixty extracted upper central incisors were decoronated and randomly divided into four groups (n = 15). After endodontic treatment, the specimens were restored with different individualized fiber-reinforced post-core foundations as follows: control group (CTRL): multiple unidirectional FRC-post + dual-cure composite-core, PFC: multiple unidirectional FRC-post + packable short fiber-reinforced composite (SFRC), BPFC: Bioblock technique with only packable SFRC, BFFC: Bioblock technique with only flowable SFRC. After core build-up, the teeth were finalized with adhesively luted CAD/CAM composite crowns. Cyclic isometric loading (5 Hz) was applied at 100 N for 5000 cycles, and then 200 N and 300 N for 15,000 cycles each in a fluid chamber. The specimens were loaded until fracture occurred or when a total of 35,000 cycles were reached. Kaplan-Meyer survival analysis was conducted, followed by pairwise log-rank post hoc comparisons (Mantel-Cox).

RESULTS

The survival rates of the control (8279 cycles) and PFC (6161 cycles) were significantly higher compared to BPFC (3223 cycles) and BFFC (2271 cycles) (p < 0.05). Regarding fracture pattern, nearly all specimens fractured in a restorable manner.

CONCLUSIONS

For restoring extensively damaged anterior teeth, multiple unidirectional FRC posts are recommended.

CLINICAL RELEVANCE

Although different FRC post/core systems are available for the restoration of damaged root canal treated anterior teeth, multiple unidirectional FRC posts tend to be a good option when the ferrule is missing.

Magnetic extrusion technique for restoring severely compromised teeth: A case report

An orthodontic magnetic extrusion technique is described for the management of an extensively damaged maxillary premolar. A cylindrical neodymium-iron-boron (Nd₂Fe₁₄B) magnet was attached to the remaining tooth structure, and a second magnet was placed on a resin-bonded partial denture. A 4.5-mm extrusion was obtained after 3 adjustments, and the tooth was prepared with a 3-mm buccal and 2-mm lingual ferrule by following a biologically oriented preparation technique and restored with a monolithic zirconia crown. Eighteen months after completing the treatment, no evidence of soft tissue dehiscence, abnormal tooth mobility, endodontic failure, or root resorption was found.

Coronal restoration of the root filled tooth - a qualitative analysis of the dentists' decision-making process

Aim

To describe the decision‐making process of the general dental practitioner (GDP) underlying the choice of coronal restoration of a root filled tooth.

Methodology

GDPs were strategically selected with respect to gender, age, undergraduate dental school, service affiliation and duration of professional experience. Semistructured in‐depth interviews were conducted, focusing on the informant’s personal experience of the process which leads to a decision as to how to restore a root filled tooth. The informants were invited to describe in their own words the latest two cases involving decisions of direct or full crown restorations respectively. The interviews were digitally recorded and transcribed verbatim. Interviews from 14 informants, aged 27–64 (mean age 46 years), were included and analysed according to Qualitative Content Analysis.

Results

A theme (latent content) was identified: Clinical factors were considered important but were overruled by context and patient opinions, if in conflict. Three main categories, including seven subcategories (manifest content), were identified. The categories were clinical factors, contextual factors and patient's views. Clinical factors underlying the GDPs' decision included the current dental status and the estimated longevity of the intended restoration. In certain cases, contextual factors were also of importance, either supporting the GDPs' decision or modifying it. However, the patient's views played a decisive role in the final choice of coronal restoration, leading to either mutual acceptance or a compromise, taking into account the patient's economic status and opinions.

Conclusions

With respect to coronal restoration of a root filled tooth, the GDPs’ decision‐making process was based not only on clinical factors, but also on decisive contextual factors and consideration of the patients’ views.

Effect of Fiber Posts on Stress Distribution of Endodontically Treated Upper Premolars: Finite Element Analysis

By means of a finite element method (FEM), the present study evaluated the effect of fiber post (FP) placement on the stress distribution occurring in endodontically treated upper first premolars (UFPs) with mesial–occlusal–distal (MOD) nanohybrid composite restorations under subcritical static load. FEM models were created to simulate four different clinical situations involving endodontically treated UFPs with MOD cavities restored with one of the following: composite resin; composite and one FP in the palatal root; composite and one FP in the buccal root; or composite and two FPs. As control, the model of an intact UFP was included. A simulated load of 150 N was applied. Stress distribution was observed on each model surface, on the mid buccal–palatal plane, and on two horizontal planes (at cervical and root-furcation levels); the maximum Von Mises stress values were calculated. All analyses were replicated three times, using the mechanical parameters from three different nanohybrid resin composite restorative materials. In the presence of FPs, the maximum stress values recorded on dentin (in cervical and root-furcation areas) appeared slightly reduced, compared to the endodontically treated tooth restored with no post; in the same areas, the overall Von Mises maps revealed more favorable stress distributions. FPs in maxillary premolars with MOD cavities can lead to a positive redistribution of potentially dangerous stress concentrations away from the cervical and the root-furcation dentin.

Stress Distributions for Hybrid Composite Endodontic Post Designs with and without a Ferrule: FEA Study

The aim of the current work was to analyze the influence of the ferrule effect for hybrid composite endodontic post designs consisting of carbon (C) and glass (G) fiber-reinforced polyetherimide (PEI), in upper canine teeth. Starting from theoretical designs of C-G/PEI hybrid composite posts with different Young's moduli (Post A-57.7 GPa, Post B-31.6 GPa, Post C-graduated from 57.7 to 9.0 GPa in the coronal-apical direction) in endodontically treated anterior teeth, the influence of the ferrule effect was determined through finite element analysis (FEA). On the surface of the crown, a load of 50 N was applied at 45° to the longitudinal axis of the tooth. Maximum principal stresses were evaluated along the C-G/PEI post as well as at the interface between the surrounding tooth structure and the post. Maximum stress values were lower than those obtained for the corresponding models without a ferrule. The presence of a ferrule led to a marked decrease of stress and gradients especially for posts A and B. A less marked effect was globally found for Post C, except in a cervical margin section along a specific direction, where a significant decrease of the stress was probably due to local geometric features, compared to the model without a ferrule. The presence of a ferrule did not generally provide a marked benefit in the case of the graduated Post C, in comparison to other C-G/PEI posts. The outcomes suggest how such a hybrid composite post alone should be sufficient to optimize the stress distribution, dissipating stress from the coronal to the apical end.

Dentists' perspectives on the reconstruction possibilities of a non-vital tooth

Background and aims

The decision-making process when restoring a non-vital tooth is influenced by multiple factors. This study aimed to survey the dentists’ preferences regarding cast post-and-core and fiber post techniques for the reconstruction of non-vital teeth and to identify a correlation between reconstruction technique and practitioners characteristics, or dental characteristics.

Methods

The survey instrument was a questionnaire, which included a general part with questions regarding the practitioner’s profile (gender, age, years of experience, pattern and location of practice, etc.) and the dental characteristics (anterior or posterior position of the tooth on the arch, the amount of dental remaining tissues, etc.) and a technical part, containing more specific questions regarding the manufacture and performance of root-coronal reconstructions.

Results

Among the surveyed practitioners (n=35), 69.7% use more often cast post-and-core reconstructions (CPR) while 30.3% choose fiber post reconstructions (FPR). No difference in the reconstruction type was observed regarding patient’s age (p=0.23) or gender (p=0.092). The para-function criterion was considered important by 8.23% of the participants. When deciding the type of the root-coronal reconstruction depending on the remaining dentine walls, CPRs are significantly more frequently used in posterior areas (p=0.043) or when para-functional habits exist (p=0.022).

Conclusion

Cast post-and-core represent the most frequently used type of reconstruction for non-vital teeth. Fiber post reconstructions are indicated in the aesthetic zone and when the amount of healthy remaining dental structure is higher.

Fracture resistance and marginal gap formation of post-core restorations: influence of different fiber-reinforced composites

OBJECTIVES

The aim was to explore the fracture behavior and marginal gap within the root canal of endodontically treated (ET) premolars restored with different fiber-reinforced post-core composites (FRCs). Further aim was to evaluate the composite curing at different depths in the canal.

MATERIALS AND METHODS

Eighty-seven intact upper premolars were collected and randomly divided into six groups. After endodontic procedure, standard MOD cavities were prepared and restored with their respective fiber-reinforced post-core materials: group 1: prefabricated unidirectional FRC-post + conventional composite core; group 2: prefabricated unidirectional FRC-post + short fiber composite (SFRC) core; group 3: individually formed unidirectional FRC-post + conventional composite core; group 4: randomly oriented SFRC directly layered as post and core; group 5: individually formed unidirectional FRC + randomly oriented SFRC as post and core. After restorations were completed, teeth (n = 3/group) were sectioned and then stained. Specimens were viewed under a stereo microscope and the percentage of microgaps within the root canal was calculated. Fracture load was measured using universal testing machine.

RESULTS

SFRC application in the root canal (groups 4 and 5) showed significantly higher fracture load (876.7 N) compared to the other tested groups (512-613 N) (p < 0.05). Post/core restorations made from prefabricated FRC-post (group 1) exhibited the highest number of microgaps (35.1%) at the examined interphase in the root canal.

CONCLUSIONS

The restoration of ET premolars with the use of SFRC as post-core material displayed promising performance in matter of microgap and load-bearing capacity.

CLINICAL SIGNIFICANCE

Fracture resistance of ET premolar restored by bilayered composite restoration that includes both SFRC as post-core material and surface conventional resin seems to be beneficial.