Post Placement Affects Survival of Endodontically Treated Premolars

Effect of a circumferential ferrule on the survival and success of endodontically treated teeth restored with fiber posts: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The success of endodontically treated teeth (ETT) is influenced by factors that include the use of prefabricated glass fiber posts. A consideration for success is the presence of a circumferential ferrule, but systematic reviews and meta-analyses are lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to assess the impact of the presence or absence of a circumferential ferrule on the survival and success rates of ETT restored with prefabricated fiber posts.

MATERIAL AND METHODS

Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search of the major scientific literature databases was conducted. Eligible studies included randomized clinical trials and prospective cohort studies with a minimum 6-month follow-up, focusing on ETT restored with fiber posts either with or without a uniform circumferential ferrule. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated to compare outcomes. The degree of variability among studies was assessed using the chi-squared test (α=.05).

RESULTS

Of 3731 identified records, 8 were eligible for inclusion. Direct analysis of success rates (2 studies, 123 teeth) showed a significant increase in success when a uniform circumferential ferrule was present (RR=1.28, 95% CI: 1.06, 1.54, P<.05). However, indirect analysis of survival and success rates (8 studies, 407 teeth) indicated no significant differences in outcomes between the ferrule and no ferrule groups (P>.05).

CONCLUSIONS

The results of this systematic review and meta-analysis determined that a uniform circumferential ferrule had a positive effect on the success rates of ETT restored with prefabricated fiber posts. However, further high-quality studies are required to provide more robust evidence and to allow potential confounding factors to be considered.

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

AIM

In comparing the effectiveness and efficiency of different types of post removal systems in removing different types of fiber posts (FPs), this study aims to shed light on the success of removal by currently available drill systems.

MATERIALS AND METHODS

A total of 200 maxillary first molars, were root canal treated and prepared to receive posts. The molars were divided into four groups corresponding to four different FPs: Group RX, Radix FP; Group RF, Reforpost Glass Fiber; Group HI; Hi-Rem Endodontic Post; and Group DT, D.T. Light-Post Illusion X-RO. Fiber posts were done with luting by Gradia Core (GC America, Inc.). Groups were again divided into five subgroups corresponding to the technique by which the FP was removed into as follows: Subgroup P, PD-25-1.1 Drill; subgroup G, GC FP Drill; subgroup E, EasyPost Precision Drill; subgroup R, Reaccess Carbide Double Taper Kit; and subgroup H; H-Endodontic Drill. After posts were removed, effectiveness and efficiency were documented. Data were tabulated and statistically analyzed.

RESULTS

Strong significant differences regarding efficiency among groups (FP type) and subgroups (drills used) (p = 0.00) were shown by the one-way analysis of variance (ANOVA) test. Subgroup DT-G scored the longest mean removal time (20.9 minutes) while Subgroup RX-R scored the shortest mean removal time (1.4 minutes) Regarding effectiveness, strong significant differences among groups (p = 0.00) and subgroups (p = 0.00) were shown by one-way ANOVA. Subgroup RF-G scored the highest scale (5.2) whereas subgroup HI-R scored the lowest mean scale (1.2).

CONCLUSION

The difference was strongly significant between tested post-removal kits and between tested FPs. Re-access Carbide Double Taper Kit performed superiorly in both effectiveness and efficiency, followed by PD-25-1.1 Drill. Hi-Rem post showed the best retrieving results among other FPs.

CLINICAL SIGNIFICANCE

Knowing the best technique and tools for post removal could spare the practitioner any unwanted complications during post removal. How to cite this article: Sayed M, Alahmad AM, Alhajji KS, et al. Removal Efficiency and Effectiveness of Four Different Fiber Posts Using Five Different Drill Systems in Multirooted Teeth. J Contemp Dent Pract 2024;25(1):72-78.

Comparative effectiveness of fiber and metal posts in the restoration of endodontically treated teeth: A systematic review with network meta-analysis

STATEMENT OF PROBLEM

Different varieties of fiber and metal intraradicular posts have been used for the restoration of endodontically treated teeth with insufficient sound tooth structure. Evidence on the comparative efficacy of posts in a clinical setting is insufficient to provide clear clinical guidelines and recommendations.

PURPOSE

The purpose of this systematic review with network meta-analysis was to assess the comparative efficacy of fiber and metal posts used for the restoration of endodontically treated teeth.

MATERIAL AND METHODS

A search was conducted for trials published in Medline, Scopus, PubMed, and Cochrane Central Register of Controlled Trials from inception until November 2022. The study was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42022384340). A network meta-analysis was performed on data from randomized controlled trials that assessed the comparative efficacy of fiber posts and metal posts for the restoration of endodontically treated teeth. Subgroup analyses were performed to compare all the varieties of fiber and metal posts. The types of posts were ranked according to their efficacy using the Surface Under the Cumulative Ranking (SUCRA) system. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach was used to assess the level of certainty of evidence.

RESULTS

Twenty-five articles were included in the quantitative analysis. Fiber posts (RR=0.15 [95% CI: 0.06, 0.33]) significantly prevented tooth fracture as compared with no posts. Prefabricated carbon fiber posts (RR=0.06 [95% CI: 0, 0.54]) ranked highest followed by custom glass fiber posts (RR=0.15 [95% CI: 0.04, 0.52]) and prefabricated glass fiber posts (RR=0.22 [95% CI: 0.07, 0.62]) in the outcome of tooth fracture. Metal posts (RR=0.24 [95% CI: 0.12, 0.46]) ranked higher than fiber posts (RR=0.39 [95% CI: 0.27, 0.56]) in the outcome of debonding. Custom gold alloy posts (RR=0.12 [95% CI: 0.03, 0.48]), prefabricated gold alloy posts (RR=0.04 [95% CI: 0.00, 0.87]), and prefabricated titanium posts (RR=0.21 [95% CI: 0.10, 0.45]) had higher rankings in the outcome of debonding or loss of retention of a post followed by custom glass fiber posts (RR=0.37 [95% CI: 0.21, 0.63]) and prefabricated glass fiber posts (RR=0.38 [95%CI: 0.25, 0.58]). Prefabricated glass fiber posts (RR=0.40 [95% CI: 0.20, 0.81]) had statistically significant differences in the outcome of secondary caries. The GRADE approach determined a moderate level of certainty of evidence.

CONCLUSIONS

The use of a fiber post when indicated results in reduced risk of tooth fracture as compared with no post. Prefabricated carbon fiber posts, prefabricated glass fiber posts, and custom glass fiber posts reveal a lower risk of tooth fracture. Overall, the use of prefabricated glass fiber posts had a lower risk of tooth fracture, debonding, and secondary caries. However, more trials with longer follow-up periods are recommended to enhance the certainty of evidence.

Evidence-based fact checking for selective procedures in restorative dentistry

OBJECTIVES

Similar to other dental specialties, there are many clinical procedures in restorative dentistry that may or may not be supported by good evidence. Thus, the effectiveness of these procedures is uncertain. The aim of this paper is to reduce this knowledge gap by critically inspecting selective procedures in restorative dentistry and exploring if these well-established or widely advocated treatment modalities are necessary for improving treatment outcomes based on the best available evidence.

MATERIALS AND METHODS

A MEDLINE search was conducted to identify research on selective procedures while focusing on clinical trials and systematic reviews. Due to their practical relevance in the decision-making process, cost-effectiveness analyses were also included.

RESULTS

Mixed results were identified regarding the included interventions. Some procedures had adequate evidence supporting them while others were mostly based on beliefs.

CONCLUSIONS

A critical review of the available literature indicates that some common restorative procedures lack adequate support from high-quality research evidence.

CLINICAL RELEVANCE

This paper attempts to highlight the need to critically examine the scientific validity of traditional knowledge and techniques through the context of current research evidence. This will not only help generate consensus between educators, clinicians, and researchers regarding restorative procedures but will also lead to improved patient care and outcomes.

Probability of survival and failure mode of endodontically treated incisors without ferrule restored with CAD/CAM fiber-reinforced composite (FRC) post-cores

PURPOSE

This study evaluated the probability of survival and failure mode of endodontically treated incisors without ferrule restored with CAD/CAM FRC post-cores.

METHODS

Root canals of bovine incisors were treated, leaving post preparations of ∼10 mm. Teeth were allocated into three groups: (i) cast metal post-core, (ii) FRC prefabricated post with a direct resin core build-up, and (iii) CAD/CAM FRC post-core. Posts and zirconia crowns were cemented using resin cement. Specimens were subjected to step-stress accelerated-life fatigue testing in water. Use level probability Weibull curves, probability of survival for a mission of 100,000 cycles at 25, 50, and 100 N, Weibull modulus, and characteristic strength were calculated and plotted. Failure mode was examined under a stereomicroscope.

RESULTS

Restored incisors demonstrated high probability of survival (93-100%) for missions estimated at 25 and 50 N, irrespective of post-core foundation. At 100 N, incisors restored with metal posts presented significantly higher probability of survival (99%) relative to CAD/CAM posts (79%), whereas FRC groups demonstrated no significant difference. Weibull analysis indicated no significant difference on the Weibull modulus (m = 3.38-5.92). Incisors reconstructed with metal post-cores (431 N) presented significantly higher characteristic strength relative to prefabricated (200 N) and CAD/CAM (202 N) FRC post-cores. While post fracture was the chief failure mode for prefabricated and CAD/CAM FRC post-cores, post and/or root fracture were the main event for metal post-cores.

CONCLUSION

Endodontically treated incisors without ferrule restored with CAD/CAM FRC post-cores presented promising probability of survival for loads compatible with anterior masticatory forces and favorable failure modes.

Success of fixed partial denture prostheses observed in a military dental centre: A cross-sectional study

Background

Fixed dental prostheses have been provided in the Armed Forces for a long time, yet definite evidence-based guidelines on the success and failure of different types of prostheses are currently lacking. A cross-sectional observational study was conducted as a step towards addressing this lacuna.

Methods

The study included 156 patients and 538 prostheses based on pre-established inclusion criteria. The types of prostheses that were evaluated included crowns, fixed partial dentures (FPDs), post and core restorations, dental implants and veneers. Visual, tactile and radiographic examination was used for evaluating the prostheses. Success, survival and failure of prostheses were evaluated, and the types of complications leading to the failure were also recorded. In addition, the oral hygiene status of the included patients was also evaluated using the Oral Hygiene Index-Simplified.

Results

The overall failure rate in all prostheses combined together was 28.81%. The failure rate in cantilever FPDs was the highest at 44.44%. It was 16.67% in veneers, 35.37% in conventional FPDs, 23.81% in single crowns and 30.56% in all post and core restorations.

Conclusion

Barring the all-ceramic prostheses and fibre post and core restorations, the rate of occurrence of both complications and failures in the remaining categories of prostheses was higher than that mentioned in the literature.

Finite element and in vitro study on biomechanical behavior of endodontically treated premolars restored with direct or indirect composite restorations

Objectives of the study were to investigate biomechanical properties of severely compromised premolars restored with composite restorations using finite element analysis (FEA), and in vitro fracture resistance test. A 3-D model of an endodontically treated premolar was created in Solidworks. Different composite restorations were modelled (direct restoration-DR; endo-crown-EC; post, core, and crown-C) with two different supporting tissues: periodontal ligament/alveolar bone (B), and polymethyl methacrylate (PMMA). Models were two-point axially loaded occlusally (850 N). Von Mises stresses and strains were calculated. The same groups were further tested for static fracture resistance in vitro (n = 5, 6.0 mm-diameter ball indenter, vertical load). Fracture resistance data were statistically analyzed (p < 0.050). The highest stresses and strains in all FEA models were observed on occlusal and vestibular cervical surfaces, corresponding to fracture propagation demonstrated in vitro. C showed the lowest stress in dentin, while EC showed lower stresses and strains in crown cement. B models demonstrated larger high stress areas in the root than PMMA models. No significant differences in fracture resistance (N) were observed between groups (DR: 747.7 ± 164.0, EC: 867.3 ± 108.1, C: 866.9 ± 126.3; p = 0.307). More conservative restorations seem a feasible alternative for endodontically treated premolars to conventional post-core-crown.

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.

A critical analysis of research methods and experimental models to study the load capacity and clinical behavior of the root filled teeth

The prognosis of root‐filled teeth depends not only on a successful root canal treatment but also on the restorative prognosis. This critical review discusses the advantages and limitations of various methodologies used to assess the load capacity or clinical survivability of root‐filled teeth and restorations. These methods include static loading, cyclic loading, finite element analysis and randomized clinical trials. In vitro research is valuable for preclinical screening of new dental materials or restorative modalities. It also can assist investigators or industry to decide whether further clinical trials are justified. It is important that these models present high precision and accuracy, be reproducible, and present adequate outcomes. Although in vitro models can reduce confounding by controlling important variables, the lack of clinical validation (accuracy) is a downside that has not been properly addressed. Most importantly, many in vitro studies did not explore the mechanisms of failure and their results are limited to rank different materials or treatment modalities according to the maximum load capacity. An extensive number of randomized clinical trials have also been published in the last years. These trials have provided valuable insight on the survivability of the root‐filled tooth answering numerous clinical questions. However, trials can also be affected by the selected outcome and by intrinsic and extrinsic biases. For example, selection bias, loss to follow‐up and confounding. In the clinical scenario, hypothesis‐based studies are preferred over observational and retrospective studies. It is recommended that hypothesis‐based studies minimize error and bias during the design phase.

Survival Rates of Endodontically Treated Posterior Teeth Restored with All-Ceramic Partial-Coverage Crowns: When Systematic Review Fails

Background: To determine the survival rates of endodontically treated posterior teeth (EDPT) restored with partial coverage all-ceramic crowns with or without the use of fiber posts. Methods: MEDLINE and Cochrane searches were conducted in order to identify Randomized Clinical Trials (RCTs) related to endodontically treated posterior teeth restored with partial coverage crowns. The search period was extended until February 2020 and only in vivo, human, and studies in the English language were included. A manual search was also conducted and additional articles, if found, were included in the database. Results: The initial search for the selected databases identified 495 studies, which were all screened for inclusion through titles, abstracts and full-text reading. Out of these 495 studies, only one article met the eligibility criteria and was included in this systematic review. Statistical analysis could not be performed. Conclusions: Only one RCT was identified in this systematic review. More clinical evidence is necessary to assess the survival rate of EDPT with partial-coverage crowns. This systematic review failed because it did not find scientific evidence to support the use of indirect bonded restorations on EDPT.

Influence of presence or absence of posts on the failure rates of post endodontic restorations: A systematic review and meta-analysis

Aim

The study was designed to evaluate the existing evidence on the failure rates of post-endodontic restorations retained with and without post in endodontically treated teeth (ETT).

Settings and Design

Preferred Reporting Items for Systematic Reviews and Meta-Analyses- Protocol (PRISMA-P) guidelines were used to formulate the review.

Materials and Methods

Randomized controlled trials (RCT's) and prospective clinical studies comparing post endodontic restorations retained with and without post were included. PubMed/Medline, Embase, Cochrane Library and Scopus databases were searched to recognize relevant full-text articles in English language. The quality of the RCT's were evaluated using the Cochrane collaboration tool to assess the risk of bias and reported as having high, low or unclear risk. Random-effects model at a 95% confidence interval was used for the meta-analysis.

Statistical Analysis Used

Meta-analyses was performed using the Mantel -Haenszel method31 and risk ratio, with a 95% confidence interval (CI), was estimated for dichotomous data. Random effects model32 was used as the pooling method and 95% confident interval (α = .05 for RR values) in Review Manager (RevMan) [Computer program]. Version 5.4. The Cochrane Collaboration, 2020).

Results

Four studies comparing post retained and post free restorations in ETT with a total of 916 restorations were included in the analysis. The total risk ratio was 2.16, (95% CI:1.25 to 3.72).

Conclusion

ETT with post retained restorations exhibited significantly lower failure rates compared to restorations without post. Well-designed RCT's are warranted to develop a clinical protocol with respect to post-retained restorations.

Endodontic Irrigants and Their Activation Efficacy on Cleansing Post-Space Root Canal Walls

The aim of this study was to evaluate the efficacy of activated irrigants (EDTA e NaOCL) during the cleansing of root walls, of the smear layer, of the debris, and gutta-percha after the preparation of the restorative space. Twenty single and multi-rooted (n = 20) have been collected. All samples were prepared by the same operator, using Nickel-titanium rotating instruments (Mtwo) through the Simultaneous Shaping Technique. The continuous-wave of condensation technique of obturation was used. To all specimens, the restorative space has been made, leaving 5 mm of apical gutta-percha, and postoperative periapical X-rays were performed. The samples were randomly divided into two groups: Group (A): cleansing of the root walls with ultrasonic activation of the irrigants (NEWTRON P5 XS; Satelec Acteon); Group (B): radicular walls wash without ultrasonic activation of endodontic irrigants (NaOCl 5.25% and EDTA 17%). Both dental sample groups were cut longitudinally with a low-speed saw (Isomet); the samples were observed by using a scanning electron microscope (Jeol, Jsm-6060LV) in order to evaluate: (1) the amount of debris/smear layer; (2) the mount of obstruction of dentinal tubules found in the two groups; and (3) evaluation of the presence of gutta-percha. Then, the other five samples each group (with and without ultrasonic activation) were prepared following the same protocol. Then, a universal bonding system (G-Praemio Bond, GC) and a layer of a flowable resin composite (Gaenial Flow, GC) were light-cured and used on top of the prepared root canal walls. The samples were cut in two pieces along the long axis of the root. Then, half sample teeth were kept in an acidic solution (37% HCl) for 48 h in order to completely dissolve dental structures and to have a direct view of resin tags formation under SEM. The other half was prepared to observe the adhesive interface under SEM. The amount of debris was not satisfactory in 9 out of 10 cases in Group B, while in Group A, which has been treated with ultrasounds, the result was either good or great in most of the samples. For the sample group treated with ultrasound, the tubules were evaluated as perfectly clean in 9 out of 10 cases, instead, the results are unsatisfactory for 9 out of 10 cases of group B not treated with ultrasound. Differences between Group A and B were statistically significant. With respect to the presence of debris and tubules obstruction treatment with ultrasonic activation, it offers with no doubt better results. When ultrasonic activation is used in combination with endodontic irrigants, a clean dentin substrate is be obtained for the adhesion of restorative materials, but in order to confirm the findings of this study, further in vivo trials are needed.

Influence of remaining axial walls on of root filled teeth restored with a single crown and adhesively bonded fibre post: A systematic review and meta-analysis

OBJECTIVES

To synthesise evidence on structural failures and prevalence of post-treatment endodontic disease (PTD) in anterior and posterior root filled teeth with a single crown and adhesively bonded fibre post with regards to the number of axial walls.

DATA

An electronic search was performed, no language constraints or restriction on the year of publication were applied.

SOURCES

PubMed, Medline, Cochrane and Scopus on 13th of July 2021.

STUDY SELECTION

Clinical studies that reported the remaining number of axial walls for permanent anterior and posterior root filled teeth (RFT) restored with single crowns and adhesively bonded fibre posts with a minimum of 1 year follow-up were included. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines [1] were used. The number of axial walls and the success/failures were analysed as follows: fibre post and/or core decementation, post and/or core fracture and post treatment endodontic disease, and root fracture.

CONCLUSIONS

A total of 811 studies were identified with 5 meeting the inclusion criteria. The two randomized controlled trials included had 'some concerns' as determined by the Cochrane risk-of-bias 2 tool while the Newcastle-Ottawa scale found low risk of bias for the remaining three studies. The random effects model for subgroup meta-analysis revealed failures for posterior RFT increased with decreasing numbers of remaining walls. Failures for 0 remaining walls were 23% (95% CI = 10% - 36%) and for one remaining wall 15% (CI: 3% -26%), irrespective of follow-up times. Fibre post debonding and PTD increased with decreasing numbers of walls. Relative & catastrophic failure of posterior teeth restored with a fibre post and single crown after root canal treatment increased with decreasing numbers of remaining axial walls.

CLINICAL SIGNIFICANCE

This synthesis is unique as it minimizes the presence of confounding factors by reviewing evidence of failures and post-treatment endodontic disease associated with teeth restored with single crowns. Therefore, it provides valuable predictive evidence of potential coronal restoration catastrophes and post-treatment endodontic disease associated with root filled teeth.

Post-retained Restorations: A Cost-minimization Analysis Nested in a Randomized Clinical Trial

OBJECTIVES

The aim of this study was to assess four post-retained restorative strategies for endodontically treated teeth using cost-minimization analysis.

METHODS AND MATERIALS

The cost-minimization analysis was based on primary data from a randomized clinical trial and followed the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) guidelines. Two hundred twenty-five teeth (141 patients) restored using four strategies-teeth with ferrules+ restored with either glass fiber posts or direct composite or crowns, and teeth without ferrules- restored with either glass fiber or cast metal posts with crowns-were evaluated annually between 2009 and 2018. Initial costs and incremental costs per year were calculated. Survival curves were created using the Kaplan-Meier method and log-rank test. Kruskal-Wallis analysis was followed by Dunn's test, which was used to compare restorative treatments, with a significance level of 5%.

RESULTS

Initial costs were greater for cast metal posts without crowns (US$153.14). Glass fiber posts with composite (US$27.11) were least costly; the most failures occurred in this group, but they were primarily repairable restoration fractures. The number of extractions, and thus cost, was greater for glass fiber posts with crowns. The mean annual cost was significantly lower for teeth restored with composite (p<0.001). Ferrule presence did not significantly impact annual costs.

CONCLUSIONS

The use of glass fiber posts and direct composite incurred significantly lower annual costs than did other alternatives involving crowns or metal posts.

Effect of different surface treatments on the bond strength of milled polyetheretherketone posts

STATEMENT OF PROBLEM

Polyetheretherketone (PEEK) can be used as a framework material for removable and fixed dental prostheses. However, information about the use of PEEK as a post-and-core restoration is scarce.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of different surface treatments on the push-out bond strength of milled polyetheretherketone posts to resin cement.

MATERIAL AND METHODS

Sixty intact human maxillary central incisors were selected and endodontically treated, and standardized post spaces were prepared. Sixty PEEK posts were milled from a prefabricated PEEK blank by using a computer-aided design and computer-aided manufacturing (CAD-CAM) system and divided into 3 groups (n=15) according to the surface treatment: acid etching by using 98% sulfuric acid (AE); airborne-particle abrasion by using 50-μm Al₂O₃ (AA); nonthermal plasma treatment (NTP); in addition, PEEK posts (n=15) received no treatment (NT) and served as a control. All posts were bonded by using a self-adhesive resin cement. Three sections (coronal, middle, and apical) were obtained for each specimen. Push-out bond strength measurements (MPa) for each section were recorded by using a universal testing machine at a crosshead speed of 0.5 mm/min until failure occurred. The post-cement interfaces and failure modes were evaluated by using scanning electron microscopy. The data obtained were statistically analyzed by using 1-way ANOVA and the pair-wise Tukey (HSD) test to study the difference between group mean values (α=.05).

RESULTS

The overall mean ±standard deviation of the push-out bond strength was 11 ±2 MPa for AE group, 6 ±1 MPa for AA group, 5 ±1 MPa for NTP group, and 3 ±1 MPa for NT group. A statistically significant difference was found among all groups subjected to different surface treatments as indicated by the ANOVA test (P<.001). The pair-wise Tukey honestly significant difference (HSD) test showed a significant difference among the AE group and all groups (P<.001); however, no significant difference was observed between the AA and NTP groups (P>.05). Moreover, a significant difference was observed among all root sections (P<.001).

CONCLUSIONS

Surface treatment of PEEK posts with 98% sulfuric acid for 60 seconds showed significantly higher bond strength values than those in other groups. The bond strength of PEEK posts to resin cement was significantly higher in the coronal section than that in other sections.

Influence of single post, oval, and multi-post restorative techniques and amount of residual tooth substance on fracture strength of endodontically treated maxillary premolars

PURPOSE

The aim of this study was to compare the influence of the number of coronal walls and post-endodontic restorations on the mechanical strength of 165 recently extracted endodontically treated maxillary premolars.

METHODS

The teeth were divided into 3 control (no post) and 3 test groups according to the number of residual walls. Each test group was divided into subgroups according to the type of post-endodontic restoration (single, oval, and multi-post techniques). Samples were prepared conforming to the assigned subgroup. A universal loading machine applied a load parallel to the longitudinal axis of the teeth, thus simulating physiological occlusion. ANOVA and the Kruskal Wallis test were used for comparisons (P ≤ 0.05), and Tukey's test for multiple comparisons.

RESULTS

For intact teeth, significant differences were found among all 3 subgroups, with single post showing the highest values. For 3 residual walls, oval post resulted in significantly lower values than single and multi-post systems. For 2 residual walls, the multi-post technique showed almost twice the resistance of oval post restorations.

CONCLUSION

In oval canals the use of a single or multi-post technique increased post-and-core resistance even in intact teeth, whereas oval fiber posts showed no improvements. Multi-post design improved fracture resistance mostly in maxillary premolars lacking both marginal ridges.

Longevity and Risk Factors of Post Restorations after up to 15 Years: A Practice-based Study

INTRODUCTION

The aims of this multicenter, practice-based cohort study were to evaluate the success and survival of endodontically treated teeth with post restorations (ETT+Ps) and to analyze factors associated with the longevity of ETT+Ps.

METHODS

Eight general dental practitioners each placed up to 27 ETT+Ps without any restriction to post materials or dimensions. Only incisors, canines, and premolars were included. At the last follow-up visit, ETT+Ps were considered as successful if the post and the initially placed definitive restoration were sufficient, whereas ETT+Ps were considered as survived if the post was still in function. Multilevel Cox proportional hazards models were used to evaluate the association between a range of predictors and time until no success and no survival.

RESULTS

Overall, 195 endodontic posts in 195 patients were followed up for a mean (95% confidence interval) of 91 (81-101) months; the longest follow-up was 15 years. Of these, 122 ETT+Ps were considered successful (estimated success time = 110 [101-120] months), and 152 ETT+Ps survived [estimated survival time = 133 [124-141] months). Regarding the categories of success and survival, the annual failure rates were 6.0% and 3.3%, respectively. Recementation of old (telescopic) crowns after placing new posts was the only significant predictor for decreased time until failure for both success and survival analyses. By excluding recemented restorations, annual failure rates decreased to 3.5% and 2.1%, respectively.

CONCLUSIONS

For EET+Ps placed in a private practice setting, high success and survival rates were observed. If old (telescopic) crowns were recemented after new posts were placed, the high risk of subsequent failure should be considered and communicated with patients.

In Vitro Comparison of Porcelain Fused to Metal Crown Retention after Endodontic Access and Subsequent Restoration: Composite, Amalgam, Amalgam with Composite Veneer, and Fiber Post with Composite

INTRODUCTION

The aim of this study was to evaluate the effect of different access opening restorative materials on crown retention.

METHODS

Thirty-eight extracted molars were mounted in resin and prepared for porcelain fused to metal (PFM) crowns. The crowns were fabricated and cemented with zinc phosphate, and the force to displace it was measured with a tensile-testing machine before and after endodontic access preparations. The endodontic access area, crown preparation axial wall, and preparation surface area were measured for comparison. The crowns were then recemented, and access openings were restored with either amalgam or composite before displacement force was remeasured. The restorative material was removed from each access opening; access area was measured and restored again (amalgam with composite or fiber post with composite) for displacement force to be remeasured. Paired t test was used to compare the means of displacement between groups. One-way analysis of variance was used to compare the mean outcome measure within the groups.

RESULTS

Statistical analyses showed retention after unfilled access was significantly lower than intact crowns. Amalgam, composite, amalgam + composite, and fiber post + composite increased retention beyond the original value. There was no statistical difference among the different restorative protocols. Qualitative results indicate that the restorative material remains in the crown after displacement regardless of the material used to restore the access.

CONCLUSIONS

The results from this study suggest that an endodontic access cavity decreases retention of a PFM crown. However, subsequent restoration with amalgam, composite, amalgam + composite, or post + composite may increase the original retention of the crown.

A prospective study on the effect of coronal tooth structure loss on the 4-year clinical survival of root canal retreated teeth and retrospective validation of the Dental Practicality Index

AIM

First, to examine the impact of the residual volume of coronal tooth structure in posterior teeth measured with an intra-oral scanner on the 4-year clinical survival of root canal retreated teeth. Secondly, to assess retrospectively the effectiveness of the Dental Practicality Index (DPI) in predicting the survival of root canal retreated teeth.

METHODOLOGY

A total of 156 posterior root canal treated teeth (140 patients) had baseline periapical radiographs (PA) and cone-beam computed tomography (CBCT) scans taken prior to root canal retreatment. These teeth were followed up with a clinical examination at 1, 2, 3 and 4 years (T12, T24, T36 and T48) with periapical radiographs and CBCT images taken at T12, and PA taken at T24, T36 and T48 where appropriate. Root canal retreated teeth were dichotomized into 'survived' versus 'extracted'. Fisher's exact test was used to determine the association between the volume of remaining coronal tooth structure and the 4-year tooth survival. The Dental Practicality Index for each tooth was established using the preoperative clinical and radiographical data. Fisher's exact test was used to establish a relationship between categorical variables, the total score of DPI vs tooth outcome.

RESULTS

The percentage of extractions associated with teeth with <29.5% remaining coronal tooth structure was 3 times higher (12.5%) compared to that of teeth with a residual tooth structure > 29.5% (3.5%), but with no significant difference (P = 0.073). There was a significant correlation between the outcome of root canal retreatments at 1 year, assessed by both PA and CBCT, and the 4-year survival (Fisher's exact test, P = 0.007 and P = 0.001, respectively). Teeth with DPI scores ≥ 6 were more likely to be extracted than teeth with DPI score < 6 (18.8% vs. 3.9%) (Fisher's exact test, P = 0.045).

CONCLUSION

Teeth with <30% of remaining tooth structure were associated with a survival rate above 80% and teeth with more than 30% of residual tooth structure survived in more than 94% of the cases. The radiographic outcome of root canal treatment can also help to predict tooth survival with teeth having an unfavourable outcome at 1 year more likely to be extracted within 4 years of completion of treatment. The DPI score can potentially be used to identify teeth with failed root canal treatment, which are likely to be extracted following retreatment and cuspal coverage.

Fracture Resistance and Failure Mode of Custom-made Post-and-cores of Polyetheretherketone and Nano-ceramic Composite

Clinical Relevance

Custom-made post-and-cores of polyetheretherketone (PEEK) and nano-ceramic composite showed good fracture resistance and failure mode. Clinicians should be aware that these materials might be an efficient alternative for post-and-cores, because they promote esthetics while reducing the risk of root fractures.

SUMMARY

Purpose: The purpose of this study was to evaluate the fracture resistance and failure mode of custom-made post-and-cores manufactured with different esthetic materials.

Methods and Materials: A total of 48 mandibular premolar extracted teeth were selected, endodontically treated, and prepared to receive the posts. Specimens were randomly divided into four groups (n=12/group): group 1, polyetheretherketone (PEEK, Degos; G1); group 2, nano-ceramic composite (Lava Ultimate, 3M ESPE; G2); group 3, cast metal post (NiCr alloy, control; G3); group 4, fiberglass post (Whitepost, FGM, control; G4) customized with a nano-hybrid resin composite (Z250, 3M ESPE). Experimental post-and-cores (G1 and G2) were manufactured with a computer-aided design/computer-aided manufacturing system. All posts were cemented with self-adhesive resin cement (Rely X U200, 3M ESPE), and specimens were stored in distilled water at 37°C for 60 days. A universal testing machine was used to measure the fracture resistance (0.5 mm/min at an angle of 45° to the long axis of the tooth). Fractures were classified as repairable or catastrophic. One-way analysis of variance with Tukey post hoc and χ2 tests for independence and Bonferroni adjustments were applied (α=0.05).

Results: The fracture resistance values (mean ± SD, in newtons) were 379.4 ± 119.8 (G1), 506.4 ± 138 (G2), 939.6 ± 146.5 (G3), and 449.6 ± 66.5 (G4). Only G3 exhibited a significant difference (p&lt;0.05). The χ2 test showed an association between failure mode and post-and-core material [χ2(3) = 23.65; p&lt;0.001]. After Bonferroni adjustment, only G3 presented a higher than expected incidence of catastrophic failures (p&lt;0.001). In the remaining groups, most failures were repairable and related to debonding.

Conclusions: Customized post-and-cores of PEEK and nano-ceramic composites exhibited good mechanical performance. Their fracture resistance was comparable to that observed for fiberglass customized posts, yet lower than that for cast metal posts. For PEEK post-and-cores, in particular, additional studies are needed to improve adhesiveness and reduce the risk of debonding.

Custom and prefabricated PolyEtherKetoneKetone (PEKK) post-core systems bond strength: Scanning electron microscopy evaluation

The present study evaluated the bond strengths of prefabricated PolyEtherKetoneKetone (PEKK) posts, PEKK posts custom-configured according to root-canal size, and conventional fiber posts. A total of 30 maxillary incisors were randomly divided into three groups, as follows: Group 1: fiber posts; Group 2: prefabricated PEKK posts; Group 3; custom-made PEKK posts. Following endodontic treatment, post spaces were prepared, and posts were cemented with resin cement. Push-out bond strength testing was performed using a universal testing machine, and fractures modes were examined under a scanning electron microscope. Data were analyzed using One-way ANOVA and Tukey's HSD tests, with the level of significance set at .05. The highest bond-strength values in the cervical section were observed with the custom-made PEKK post (17.3470 MPa), whereas the highest bond-strength values in the middle and apical sections were observed with the conventional fiber posts (11.5375 MPa and 6.8625 MPa, respectively). Bond-strength values for all posts systems decreased in a cervical to apical direction. PEKK posts are a suitable alternative to fiber posts. Although custom-made PEKK posts demonstrated better bond strength than prefabricated PEKK posts, further studies are needed to evaluate their clinical performance.

Development of a fiber-reinforced material for fiber posts: Evaluation of stress distribution, fracture load, and failure mode of restored roots

STATEMENT OF PROBLEM

The biomechanical behavior of post-restored roots with an experimental fiber-reinforced composite resin is unknown.

PURPOSE

The purpose of this in vitro study was to investigate the biomechanical behavior of an experimental composite resin (3-mm short glass fiber incorporated in methacrylate matrix with filler particles) used to produce the custom post itself or to reline fiber posts.

MATERIAL AND METHODS

Four testing groups (n=10) were created according to the root restoration method: FG, commercially available fiber post; FG+RC, fiber post relined with conventional composite resin; FG+EXP, fiber post relined with the experimental composite resin; and EXP, a custom post made of experimental composite resin. A three-dimensional finite element linear elastic analysis was performed by using geometric representations of groups, and the results were analyzed by von Mises (σ_vM) and maximum principal stress criteria. In sequence, 40 bovine incisors were assigned to these groups and subjected to a fracture load test (Instron 5965; 0.5 mm/min), and the failure mode was determined.

RESULTS

The EXP group showed more homogeneous stress distribution for σ_vM. ANOVA and the Tukey honestly significant difference (HSD) tests showed significant differences (P<.001) in fracture load (mean ±standard deviation; different superscript letters indicate statistical difference): FG+EXP (669.5 ±107.7)^A; FG (620.7 ±59.2)^A; EXP (506.5 ±27.0)^B; FG+RC (452.7 ±81.6)^B. No differences were found for failure mode (P=.595).

CONCLUSIONS

The experimental composite resin significantly increases fracture load when used to reline commercially available fiber posts and, irrespective of its use, presented lower stress concentration.

The Effect of Crown Lengthening on the Outcome of Endodontically Treated Posterior Teeth: 10-year Survival Analysis

INTRODUCTION

The purpose of this study was to investigate the effect of a crown lengthening (CL) procedure and the crown-root ratio after CL on the long-term survival of endodontically treated teeth (ETT).

METHODS

Permanent posterior teeth with opposing dentition that had received adequate nonsurgical root canal treatment (NSRCT) and a full-coverage crown between January 1, 2006, and January 1, 2016 were included in this retrospective study. The data collected included dates of the NSRCT, time of extraction if extracted, age, sex, location, the crown-root ratio after CL, and the presence of a lesion. All included ETT were divided into 2 groups: RESULTS: 5-year survival rates of ETT in the control and CL groups were 88.6% and 82.2%, respectively (P > .05). The 10-year survival rates of ETT in the control and CL groups were 74.5% and 51%, respectively (P < .05). ETT that received the CL procedure after NSRCT were almost 2.3 times more likely to get extracted compared with ETT that did not need the CL procedure at the 10-year follow-up (hazard ratio = 2.29, P < .05). Also, ETT with an inadequate crown-root ratio (1:1) after CL showed the lowest survival rate (40%) compared with ETT with an adequate crown-root ratio (<1:1).

CONCLUSIONS

A crown-root ratio of 1:1 after osseous CL may affect the long-term survival of ETT. Despite the promising survival rate of ETT with an adequate crown-root ratio after CL, the long-term survival of NSRCT with an inadequate crown-root ratio (1:1) should be considered in the treatment planning phase. Also, it is worth mentioning that the results of the present study should be evaluated in future prospective studies.

Success and survival of post-restorations: six-year results of a prospective observational practice-based clinical study

AIM

This prospective, noninterventional, multi-centre, practice-based study aimed to evaluate the longevity of endodontically treated teeth (ETT) restored with posts and to analyse factors influencing the success and survival of endodontic posts.

METHODOLOGY

Eight general dental practitioners each placed up to 27 endodontic posts without any restriction to size and material. Teeth were restricted to incisors, canines and premolars. Multi-level Cox proportional hazards models were used to evaluate the association between clinical factors and time until failure.

RESULTS

A total of 195 endodontic posts were followed-up for up to 6.5 years in 195 patients. Of these, 140 posts were judged as successful [mean success time: 59 (55-63) months]; the mean annual failure rate was 8.6%. This decreased to 4.4% when excluding recementations. 152 posts survived [mean survival time: 64 (60-67) months]. Recemented restorations had an eight times higher failure rate compared with new restorations. Furthermore, restorations with glass fibre post had a significantly lower success rate compared with titanium posts.

CONCLUSION

Relatively low success and survival rates occurred for restorations with posts after root canal treatment in a private practice setting after a follow-up of up to 6.5 years. Recemented crowns had a high risk of failure.

Effect of Load Cycling on the Fracture Strength/Mode of Teeth Restored with FRC Posts or a FRC Liner and a Resin Composite

The aim of the study was to comparatively evaluate the fracture strength and mode of root canal treated teeth restored with resin composites with and without posts. The lingual cusps of root canal treated first upper premolars (n = 10/group) were removed down to cervical enamel and restored with the following: group A: glass-fiber post (Glassix) followed by a particulate-filled composite resin (PFC, G-aenial posterior, 3 × 2 mm layers); group B: glass-fiber reinforced composite bulk fill liner (EverX posterior, 4 mm layer) with the PFC (2 mm layer). Specimens were immersed in H2O (1 w/37°C), then subjected to load cycling (50 N/0.2 Hz/200k cycles), and fractured under compressive loading. Failure mode was characterized by stereomicroscopy. Statistical analysis was performed by Mann-Whitney (load) and Chi-square (mode) at a = 0.05. No statistically significant differences (p = 0.273) were found in fracture load between median values of groups A (860 N) and B (1059 N). In group A, 60% of the specimens demonstrated catastrophic root fractures and 40% mixed crown fractures (tooth cusp and restoration), whereas in group B, no root fractures were found, and the failure modes were equally distributed between mixed fractures as above and fracture of the buccal cusp. These differences were statistically significant (p = 0.004). The combination of the glass-FRC bulk fill liner with the PFC diminished the catastrophic root fractures induced by FRC posts, at a similar or higher fracture load.

Effect of Polyacrylic Acid Conditioning on the Longevity of Bonding of Self - Adhesive Resin Cement to Dentin

AbstractBonding of fiber posts using self-adhesive resin cement to radicular dentin is controversial. The aim was to evaluate the effect of conditioning of polyacrylic acid on the longevity of bonding of self adhesive resin cement to dentin. Thirty six single rooted pre molars were divided into 3 groups (n=12) ARC: ScotchBond Multi Purpose + RelyX™ARC; U: RelyX™U200; PU: 11.5% Polyacrylic acid + RelyX™U200. After conditioning of the dentin, the resin cement and the post were inserted and light-activated for 60s (1200mw/cm2) and stored in distilled water (24h/37ºC). Two discs of 1 mm thickness were obtained from each root-third and tested in push-out (0.5mm/min) after 24 hours and 6 months. For statistical purposes, the data from the root thirds were grouped and the bond strength (in MPa) was analyzed using Two-Way Analysis of Variance and Tukey’s post-hoc test at 5%. The power of the test was calculated. The bonding of the U at 6 months was higher than PU at both times (p<0.001). There were no differences for time (p=0.153) or for the interaction of treatment x time (p=0.090). Adhesive fractures between the cement and dentin were prevalent. The power test was 0.97. The bonding of the RelyX™U200 was influenced by the dentin pre-treatment with poliacrylic acid and the bonding of all groups remained stable for 6 months.Keywords: Dental Cements. Dentin. Shear Strength.ResumoA adesão de pino de fibra de vidro com cimento resinoso autoadesivo à dentina é controversa. Foi objetivo avaliar o efeito do condicionamento da dentina com ácido poliacrílico na longevidade da adesão de cimento resinoso autoadesivo. Trinta e seis raízes de pré-molares uni radiculados foram divididas em 3 grupos (n=12) ARC: ScotchBond Multi Purpose + RelyX™ARC; U: RelyX™U200; PU: Ácido poliacrílico 11,5% + RelyX™U200. Após condicionamento da dentina, o cimento resinoso e o pino de fibra de vidro foram inseridos, fotoativados por 60s (1200mw/cm2) e armazenados em água destilada (24h/37ºC). Dois discos de dentina de 1 mm de espessura foram obtidos de cada terço radicular e testados em push-out (0.5mm/min) após 24 houras e 6 meses. Para análise estatística, os dados dos terços radiculares foram agrupados e resistência adesiva (em MPa) analisada por Análise de Variância de dois fatores e teste de Tukey a 5%. O poder do teste foi calculado. A adesão de the U após 6 meses foi maior que a de PU nos dois períodos (p<0,001). Não houve diferença para o fator tempo (p=0,153) nem para a interação tratamento x tempo (p=0,090). Fraturas adesivas prevaleceram entre cimento e dentina. O poder do teste calculado foi de 0,97. A adesão do RelyX™U200 foi influenciada pelo pré-tratamento da dentina com ácido poliacrílico e a adesão de todos os grupos se manteve estável até 6 meses.Palavras-chave: Cimentos Dentários. Dentina. Resistência ao Cisalhamento.

Longevity of composite build-ups without posts-10-year results of a practice-based study

AIM

The aim of this prospective, non-interventional, multi-center, practice-based study was, firstly, to evaluate the longevity of composite build-ups in endodontically treated teeth (ETT) without post placement and, secondly, to analyze factors influencing the success of these composite build-ups.

METHODOLOGY

Each of seven general dental practitioners placed up to 50 composite build-ups without additional posts in ETT. Teeth were restricted to incisors, canines, and premolars. Several clinical data were recorded for 192 coronal restorations on ETT in 192 patients. Cox proportional hazard models were applied to analyze associations between clinical factors and time until failure.

RESULTS

Within a follow-up period of 10 years, 167 restorations were judged as successful [mean success time, 110 (105-115) months] and 180 teeth survived [mean survival time, 114 (110-119) months]. The main failure type was fracture of the restoration (n = 15). The annual failure rate was 2.4%. In bivariate Cox regression, both factors such as number of restored tooth surfaces and adhesive were significantly associated with the failure rate. In multivariate Cox proportional hazards regression, none of the investigated factors were significantly associated with the failure rate.

CONCLUSION

For composite build-ups in ETT without post placement, high success rates could be found after up to 10 years of observation time. Within the limitations of the present study, none of the analyzed factors such as "tooth type" or "number of restored tooth surfaces" was a significant predictor for the failure rate.

CLINICAL RELEVANCE

Endodontically treated teeth can be successfully directly restored with composite build-ups even when no additional post is inserted.

TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00012882).

Effects of scanning technique on in vitro performance of CAD/CAM-fabricated fiber posts

This study assessed push-out strength, cement layer thickness, and interfacial nanoleakage of luted fiber posts fabricated with computer-aided design/computer-assisted manufacture (CAD/CAM) technology after use of 1 of 3 scanning techniques, namely, direct scanning of the post space (DS), scanning of a polyether impression of the post space (IS), and scanning of a plaster model of the post space (MS). Thirty premolars were randomly assigned to three groups corresponding to the scanning technique. Posts were computer-designed and milled from experimental fiber-reinforced composite blocks. The mean (±SD) values for push-out strength and cement thickness were 17.1 ± 7.7 MPa and 162 ± 24 μm, respectively, for DS, 10.7 ± 4.6 MPa and 187 ± 50 μm for IS, and 12.0 ± 7.2 MPa and 258 ± 78 μm for MS specimens. Median (interquartile range) interfacial nanoleakage scores were 3 (2-4) for DS, 2.5 (2-4) for IS, and 3 (2-4) for MS. Post retention was better for fiber posts fabricated by DS technique than for those fabricated by IS and MS. Cement thickness did not differ between DS and IS specimens, but the cement layer was significantly thicker in the MS group than in the other two groups. Scanning technique did not affect sealing ability, as the three groups had comparable nanoleakage values.

Influence of restorative procedures on endodontically treated premolars: Finite element analysis of a CT-scan based three-dimensional model

An endodontically treated tooth with mesial-occlusal-distal (MOD) cavity is often restored with composite resin. Palatal and buccal cusp reduction (MODP, MODPB), and/or fiber-reinforced composite posts (P), are used in an attempt to improve the longevity of the restoration. The aim of this study was to determine the effects of these procedures on von Mises stress values and distribution in dental tissues and restorative materials using finite element analysis. Based on CT scans of an extracted second upper premolar, six 3D endodontically treated tooth models (MOD, MODP, MODPB, MOD+P, MODP+P, MODPB+P) were created. Each model was subjected to a summary force of 150 N on the occlusal surface simulating the normal biting pattern and maximal von Mises stresses were calculated. MODP seems to reduce von Mises stress values in dental tissues and P seems to transfer some of the stresses from dental tissues to the composite filling.

Direct restoration of endodontically treated maxillary central incisors: post or no post at all?

OBJECTIVES

The aim of this ex-vivo study was to evaluate the impact of cavity size and glass-fiber post (GFP) placement on the load capability of endodontically treated maxillary incisors directly restored with resin composite.

MATERIALS AND METHODS

Ninety-six extracted human maxillary central incisors were endodontically treated and distributed to four groups (n = 24): access cavity (A), access cavity and uni-proximal class III cavity (U), access cavity and bi-proximal class III cavity (B), and decoronated tooth (D). Specimens were restored with resin composite, and 12 specimen of each group received an adhesively placed glass-fiber post (P). Prior to linear loading, specimens were exposed to thermo-mechanical loading (TCML). Statistical analysis was performed using log-rank test after TCML, Kruskall-Wallis and Mann-Whitney U test to compare load capabilities (F_max).

RESULTS

Significantly more failures occurred in group D for specimens without GFP during TCML (p = 0.001). F_max (mean (SD) in N was (A) 513 (124), (AP) 554 (201), (U) 438 (171), (UP) 537 (232) (B) 483 (219), (BP) 536 (281), D 143 (181), and DP 500 (331), and differed significantly among groups (p = 0.003). Pair-wise comparison revealed lower F_max values for group D compared to all other groups (p < 0.034) except group DP.

CONCLUSIONS

Endodontically treated maxillary central incisors with cavity sizes up to bi-proximal class III may be successfully directly restored with resin composite. Post placement shows no additional effect except for decoronated endodontically treated incisors.

CLINICAL RELEVANCE

Endodontically treated incisors with access cavities to class III cavities can be successfully restored with resin composite. Post placement for decoronated ETT is recommended.

Bond Strength of Fiber Posts to Composite Core: Effect of Surface Treatment With Er,Cr:YSGG Laser and Thermocycling

Introduction: This study aimed to determine the bond strength of fiber post to composite core following surface treatment with Er,Cr:YSGG laser at different powers and sandblasting with and without thermocycling. Methods: In this experimental study, 30 fiber posts (Glassix, Nordin, Switzerland) were randomly divided into 5 groups of sandblasting, no treatment and laser irradiation at 1, 1.5 and 2 W powers. Following composite filling and mounting, 1-mm thick sections were made for pushout bond strength testing. Half of the samples in each group were subjected to thermocycling (n=15). Two-way analysis of variance (ANOVA) was used to analyze the bond strength values. Pairwise comparisons were made using Tukey test (P<0.05). Results: Effect of treatment method on push-out bond strength of fiber post to composite core was significant (P=0.017), while thermocycling had no significant effect on bond strength (P=0.964). Pairwise comparison of surface treatment methods revealed no significant difference in groups with and without thermocycling (P>0.05), but Er,Cr:YSGG laser irradiation with 1 W power yielded significantly higher bond strength than the control group (P=0.01). Conclusion: Irradiation of Er,Cr:YSGG laser at 1 W power increased the bond strength of fiber post to composite core. Thermocycling slightly decreased the bond strength at the fiber postcore interface.

Performance of Post-retained Single Crowns: A Systematic Review of Related Risk Factors

INTRODUCTION

Numerous factors may influence the survival/success of post-retained restorations of endodontically treated teeth (ETT). The aim of this review was to assess the influence of the number of remaining coronal walls, the use or disuse of posts, and their type on the clinical performance of these restorations.

METHODS

Randomized controlled trials and controlled clinical trials for ETT restored with a combination of post/crown or no post/crown were searched for in MEDLINE, Embase, and the Cochrane Library. Two authors independently reviewed all identified titles and abstracts for eligibility. Tables were generated to summarize the included studies, and reports of randomized trials were assessed for bias using the Cochrane risk of bias tool.

RESULTS

Nine articles were identified as meeting the inclusion criteria. Teeth without ferrule presented the highest values of variation of success/survival (0%-97%), whereas teeth with remaining coronal walls (1, 2, 3, or 4 walls with ferrule) presented lower variation. The use of posts with a high elastic modulus success/survival ranged between 71.8% and 100%, whereas posts with a low elastic modulus ranged between 28.5% and 100%. The survival of crowns without posts varied between 0% and 100%. The poor performance of posts with a low elastic modulus and without posts was associated with the absence of ferrule and the preservation of only 1 coronal wall.

CONCLUSIONS

The restoration of ETT should focus on the maintenance of the coronal structure. Until more studies with longer follow-up periods are available, posts with a high elastic modulus appear to present with better performance when restoring ETT with no ferrule.

"Ferrule Comes First. Post Is Second!" Fake News and Alternative Facts? A Systematic Review

INTRODUCTION

Both the role of an endodontic post and the ferrule effect have been discussed for decades. The clinical impact of endodontic posts compared with post-free restoration with or without ferrule support was not systematically reviewed so far. It was assumed that the effect of an endodontic post compared with a post-free restoration can be evaluated only when at the same time a ferrule or no-ferrule situation was clinically compared.

METHODS

The specific PICO question was as follows: Patient: adults with sufficient endodontic treatment needing a core or post; Intervention: post-endodontic treatment using posts with or without ferrule; Comparison: post-endodontic treatment without posts with or without ferrule; Outcomes: failure rates of post/core complexes with or without ferrule support. A Medline search was performed via PubMed in June 2017 using relevant electronic databases. Additionally, hand search was performed. Only prospective clinical studies in humans comparing the success/survival of teeth restored with or without posts over a minimum time of observation of 5 years were included.

RESULTS

In total, 7 randomized controlled trials and 1 prospective clinical trial met inclusion criteria. Cochrane rating showed high risk of bias in 5 studies. Two of 3 studies support the ferrule-effect concept. Seven of 8 show no post effect. Clinical evidence regarding the influence of tooth location on its survival is scarce.

CONCLUSION

Ferrule effect and maintaining cavity walls are the predominant factors with regard to tooth and restoration survival of endodontically treated teeth. Most studies do not confirm a positive effect of post placement.

Effect of Different Ferrule Length on Fracture Resistance of Endodontically Treated Teeth: An In vitro Study

INTRODUCTION

A ferrule has been described as a key element of tooth preparation when using a post and a core. It is a vertical band of tooth structure at the gingival aspect of crown preparation. It lessens the stress transmission to the root which is due to forces from posts or bending during seating of the post. The incorporation of a ferrule can help to withstand the forces of occlusion, preserve the hermetic seal of the luting cement, and minimize the concentration of stresses at the junction of post and core.

AIM

To evaluate and compare the effect of ferrule length on fracture resistance of endodontically treated mandibular premolar teeth, restored with prefabricated glass fiber post luted with resin cement, composite core and a full coverage metal crown.

MATERIALS AND METHODS

Forty freshly extracted mandibular premolars were treated endodontically. They were randomly divided into four groups according to their ferrule height: 3 mm, 2 mm, 1 mm and 0 mm (no ferrule). All specimens were restored with prefabricated glass fibre posts (Reforpost, Angelus) and composite resin (Filtek™ Z250XT). Standardized preparation was done on each specimen to receive a cast metal crown. The specimens were thermocycled and compressive static load at a crosshead speed of 1 mm/min was applied at an angle of 30° on lingual incline of buccal cusp of the crown until failure occurred. The load (N) at failure and mode of failure were recorded. Statistical analysis was performed with Kruskal Wallis test.

RESULT

Fracture resistance values among the groups was found to be statistically significant (p<0.001). The 3 mm ferrule group had significantly higher failure load (971.99±133.07) compared to 2 mm (848.84±109.60), 1 mm (714.64±133.89) and 0 mm ferrule groups (529.36±119.95). More favourable failure modes were observed in almost all groups.

CONCLUSION

The results of this study showed that fracture resistance of endodontically treated teeth increases as ferrule length increases.

Long-term Clinical Outcomes of Endodontically Treated Teeth Restored with or without Fiber Post-retained Single-unit Restorations

INTRODUCTION

The aim of the present study was to evaluate both survival and failure rates of endodontically treated teeth restored with or without fiber post-retained restorations after a mean observation period of at least 5 years.

METHODS

A total of 144 single-rooted and multirooted teeth in 100 subjects were endodontically treated following a predetermined aseptic protocol and restored with either a fiber post and a composite core or a composite filling without intraradicular retention. A fiber post was cemented when the teeth presented with only 1 wall and/or less than one third of the remaining height of the clinical crown. After a comprehensive treatment plan, the teeth were restored with either a direct composite restoration or a single-unit crown. Endodontically treated teeth supporting fixed and removable dental prostheses and telescopic crowns were excluded from the analysis. Success was defined as tooth survival without any treatment of biological and/or technical complications.

RESULTS

The overall tooth survival rate was 89.6% after a mean observation time of 8.8 ± 2.3 years. The survival rate of teeth with a fiber post amounted to 94.3%, and for teeth without a post, it was 76.3% (P < .001). The main reason for tooth loss was root fracture (9.7%). No loss of post retention was observed. Successfully treated teeth without any biological and/or technical complications and requiring no additional treatment during the entire observation period amounted to 79.9%.

CONCLUSIONS

Endodontically treated teeth restored with fiber posts and either a direct composite restoration or a single-unit crown yielded higher survival and success rates compared with teeth restored without fiber posts. Vertical fractures of roots not containing a post represented a frequently encountered and serious problem.

Relined Fiberglass Post: Effect of Luting Length, Resin Cement, and Cyclic Loading on the Bond to Weakened Root Dentin

This study evaluated the effects of luting length of the post, the resin cement, and cyclic loading on pull-out bond strength of fiberglass posts relined with composite resin in weakened roots. The canals of 80 bovine incisors were endodontically treated and weakened with diamond burs. The teeth were randomly divided into eight groups (n=10) according to the luting procedures of the relined fiberglass post (RFP): In groups 1, 2, 3, and 4, the RFPs were luted with RelyX ARC, and in groups 5, 6, 7, and 8 they were luted with RelyX U200. In groups 1, 3, 5, and 7, the RFPs were luted at a length of 5 mm, and in groups 2, 4, 6, and 8 they were luted at a length of 10 mm. Specimens from groups 3, 4, 7, and 8 were submitted to cyclic loading. Specimens were subjected to a pull-out bond strength test in a universal testing machine. The results (MPa) were analyzed by three-way analysis of variance and the Tukey post hoc test (α=0.05). Six human upper anterior teeth were used to analyze the bond interface by confocal laser scanning microscopy (CLSM). The pull-out bond strength of RFPs luted with RelyX U200 was statistically higher than that of RelyX ARC. Cyclic loading influenced the bond strength only for the luting length of 5 mm. CLSM analysis revealed the formation of resin cement tags for both materials. Luting length is an important factor in retaining RFPs in weakened roots when they are subjected to cyclic loading, and RelyX U200 resulted in greater bond strengths to the root canal in comparison with RelyX ARC.

Modern Endodontic Principles Part 7: The Restorative Interface

The restoration of endodontically-treated teeth is a topic that has been extensively studied and yet remains controversial. The endodontically-treated tooth can be restored with a wide range of techniques of varying complexity. This article reviews the literature on this topic. Consideration is given to the ferrule and its importance in achieving success. Furthermore, consideration will be given to the use of endodontically-treated teeth as abutments for fixed and removable prostheses and the challenges this presents. Clinical recommendations are presented as guidelines to improve the predictability and outcome of treatment when restoring structurally compromised root-filled teeth. Clinical relevance: The prognosis of endodontically-treated teeth depends not only on the success of the endodontic treatment, but also on the type of reconstruction.