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

Evaluation of stress patterns in teeth with endodontic treatment and periapical lesions as abutments for fixed prosthesis: a finite element analysis study

BACKGROUND

Examining stress distributions in abutment teeth with periapical lesions is essential for understanding their biomechanical impact on dental structures and tissues. This study uses finite element analysis (FEA) to evaluate these stress patterns under occlusal forces, aiming to enhance treatment strategies and prosthetic designs.

METHODS

Three FEA models were created: a healthy mandibular premolar (Model 1), a premolar with a single crown and a lesion repaired using a fiber-post (Model 2), and 3) a premolar with a lesion repaired using fiber-post to support a four-member bridge (Model 3). A 300 N occlusal static stress was given to each model at a 45° angle to the long axis of the tooth, namely at the lingual inclination of the buccal-cusp. Deformation behaviour and maximum equivalent stress distributions were simulated on the all components, including the bony structure for each model.

RESULTS

The study showed a reduction in equivalent stress levels in trabecular and cortical bone, crown, cementum, and PDL under occlusal force, from Model 1 to Model 3. The Von Mises yield criteria values of the tooth models differed depending on the prosthetic restorations, with the highest value seen in Model 2 (133.87 MPa). Similar locations in all models showed concentrated equivalent stresses for all components. The periapical lesion area exhibited relatively low stress values for Models 2 and 3, at 0.061 MPa and 0.039 MPa, respectively. The largest level of stress was seen in the cervicobuccal areas of the tooth in all models.

CONCLUSION

Prosthetic restorations on teeth with periapical lesions resulted in varying stress and biomechanical responses in the tooth and surrounding bone tissue. These teeth can serve as abutments in a four-unit bridge when subjected to optimal occlusal stresses, based on the findings.

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.

Influence of remaining coronal tooth morphology with resin abutment and fiber post on static and dynamic fracture resistances

This study aimed to clarify the fracture resistance of resin abutments built on endodontically treated roots with the remaining coronal teeth via static and cyclic loading tests. Endodontically treated bovine roots, which had a remaining coronal tooth covered with an occupied area for a quarter and half of the circumference at the tensile side or covered the circumference at both the tensile and compressive sides, were fabricated to build up to the resin abutment. Fracture resistance was evaluated via static and cyclic loading tests by applying a load of 30° to the tooth axis. Half of the circumference of the remaining coronal tooth showed a significantly higher static fracture load and survival rate. The remaining coronal tooth on the compressive side improved the dynamic fracture resistance associated with severe fractures. The occupied area and location of the remaining coronal tooth affected the static and dynamic fracture resistances.

Does an incomplete ferrule affect the fracture of endodontically treated teeth? A systematic review of in vitro studies

OBJECTIVE

The purpose of this systematic review was to assess the impact of the incomplete ferrule on the fracture of endodontically treated teeth (ETT).

DATA

The keywords such as "incomplete ferrule," "ferrule," "ferrule effect," "residual dentin," "remaining dentin," or "remaining coronal dentin" were used for searching, and only in vitro studies investigating the incomplete ferrule effect on natural teeth were included.

SOURCES

PubMed, Medline, Embase, Cochrane Library, and Science Direct databases, and manual-searching.

STUDY SELECTION

The search strategy yielded 1633 hits, and a total of 19 in vitro studies closely related to the effect of incomplete ferrule on ETT were included.

CONCLUSION

The presence of an incomplete ferrule may significantly increase the fracture resistance of restored ETT, compared with restored ETT without ferrule. The number of residual axial walls of the incomplete ferrule may have an impact on the fracture resistance and fracture mode. The location of residual axial walls of the incomplete ferrule may affect the fracture resistance but not the fracture mode.

CLINICAL IMPLICATIONS

Limited data suggest that the presence of incomplete ferrule has a positive effect on the fracture resistance of restored ETT. An incomplete ferrule can be an alternative for restoring ETT when a complete ferrule is not present. Nevertheless, further high-quality studies are still needed to offer more robust evidence and to take potential confounding factors into account.

Clinical performance of custom-milled polyetherketoneketone (PEKK) posts and cores: A 12-month follow-up randomized controlled pilot study

OBJECTIVES

Comparing the survival rate and the cumulative success rates of custom-milled polyetherketone ketone posts and cores (MPP) with prefabricated fiber posts (PFP) in restoring compromised endodontically treated premolars.

MATERIAL AND METHODS

This was a randomized, double-blind, parallel, two-arm controlled pilot study. A total of 24 patients (12 males, 12 females), each had a compromised lower premolar, needed a root canal treatment and to be restored with post and core. Patients were randomly allocated into two groups, MPP-group: restored with MPP, and PFP-group: restored with PFP and composite cores. After that, premolars were restored with single porcelain fused to metal (PFM) crowns. Clinical and radiographic follow-ups were conducted after 3, 6, and 12 months. The Kaplan-Meier, log-Rank, and χ2 tests were used to investigate differences between the two groups at the 0.05 significance level.

RESULTS

The survival rate after 12 months in the MPP and PFP groups was 66.7% and 100%, respectively. Meanwhile, the cumulative success rates were 63.6% and 100% in the same order. The log-rank test showed a significant difference between the two groups (p = .031). The difference in cumulative success rates was also significant, as the χ2 test revealed (p = .011).

CONCLUSION

The PFP group showed a higher success rate than the MPP group and according to the failure types, PEKK posts seem to be inferior to PFP in terms of the mechanical properties and bonding to resin mechanism.

TRIAL REGISTRATION

ISRCTN, ISRCTN13456471. October, 14, 2019. (https://doi.org/10.1186/ISRCTN13456471ISRCTN13456471).

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.

Effect of the Viscosity and Application Time of Different Phosphoric Acids on the Bond Strength and Nanoleakage of Fiber Posts to Root Dentin

PURPOSE

To evaluate the effect of application time and viscosity of meta-phosphoric acid (MPA) and ortho-phosphoric acid (OPA) on the push-out resin-dentin bond strength (PBS) and nanoleakage (NL) at the adhesive-root dentin interface.

METHODS AND MATERIALS

Ninety-six roots of premolars were endodontically prepared and randomly assigned into groups according to the (i) acid (OPA and MPA), (ii) viscosity (gel and liquid), and (iii) application time (7 and 15 seconds). Fiber posts were cemented to the roots, which were then transversally sectioned into serial slices. The slices (cervical, medium, and apical) were subjected to PBS or NL. Analysis of the dentin etching pattern was performed using scanning electron microscopy (SEM). The PBS (MPa) and NL (%) data were subjected to three-way repeated-measures analysis of variance (ANOVA) and Tukey's test (α=0.05).

RESULTS

The cross-product interaction was significant for both PBS and NL (p<0.001). No significant difference in the PBS was observed with the use of OPA compared to MPA (p>0.05). Higher PBS values were observed in the groups etched for 15 seconds compared to 7 seconds, regardless of the acid, viscosity, or root third (p<0.05). Lower NL was observed for MPA etching when compared to OPA etching (p<0.05), and these values were not affected by increasing the application time or acid viscosity (p>0.05). A more pronounced etching pattern was observed with OPA than MPA regardless of the acid viscosity.

CONCLUSION

The use of 40% meta-phosphoric acid promoted adequate bond strength without increasing dentin demineralization or void spaces in the hybrid layer.

Outcome of teeth restored with CAD/CAM zirconium dioxide post-cores: a retrospective study with a follow-up period of 3-6 years

Statement of problem

Computer aided design/computer aided manufacturing (CAD/CAM) zirconia post-cores is one of the options of post crown restoration materials due to their esthetic properties and superior mechanical strength. However, the clinical effect on aesthetics and strength properties is unclear due to the lack of results of their long-term follow-up.

Purpose

This retrospective clinical study aims to analyze the survival rate, clinical manifestations, and failure factors after CAD/CAM zirconia post-core restoration.

Material and methods

Clinical and radiographic examinations were performed on 342 patients with 400 teeth for 3–6 years postsurgical follow-up examination. The patients were all received CAD/CAM zirconia post-cores and all-ceramic crowns at the Department of Prosthodontics in the public hospital. The retrospective outcomes were conducted after zirconia post restoration, including survival rate by Kaplan–Meier analysis and findings of manifestations and failure factors. The effects of gender and dental position on survival rate were analyzed by Cox–Mantel Test.

Results

This study retrospectively evaluated 261 teeth from 229 patients with a 35% drop-out rate. The survival rate was 96.0%, and the success rate was 92.4%. According to the tooth position classification, the survival rate was 100% for 101 anterior teeth, 95.4% for 69 premolars, and 88.3% for 91 molars. According to gender, the survival rate of the male group was 92.3%, while that of the female group was 98.0%, with a significant difference (P < 0.01). The complications included crown fracture (1.9%) periapical inflammation (1.9%), crown debonding (1.1%), percussion abnormal (1.9%) and root fracture (0.8%).

Conclusions

Within the limitations of this retrospective study, it can be concluded that CAD/CAM zirconia post-cores are clinically promising. Compared with the posterior teeth, CAD/CAM zirconia post-cores are more suitable for anterior teeth.

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.

An Umbrella Review of Systematic Reviews and Meta-Analyses Evaluating the Success Rate of Prosthetic Restorations on Endodontically Treated Teeth

Materials and Methods

The electronic search was conducted in the MEDLINE/PubMed, Cochrane, and Google Scholar databases until November 2020, regardless of language limitations. The inclusion criterion was as follows: S/M-R regarding prosthetic restorations in endodontically treated teeth. Three qualified researchers evaluated the inclusion criteria and bias risk. The fourth investigator was referred to when facing any doubtfulness.

Results

From 43 achieved S/M-R, 14 studies were selected for this inquiry. Primary extracted information included success rate, survival rate, and postendodontic failure rate. Five S/M-R had a moderate risk of bias, and nine S/M-R had a low risk of bias and were considered strong clinical evidence in this examination. According to the low-risk reports, the success rate of fiber posts was higher than that of metal posts; the rate of root fracture in metallic and fiber posts was alike; the failure rate for fiber posts was comparable to fixed partial dentures or single crowns; the construction of endocrowns was likely to perform better than intracanal posts, composite resin, or inlay/onlay restorations.

Conclusion

It appears that with practice and experience, deciding which type of restoration to choose changes. In dental restorations associated with root canal therapy, the single crowns are likely to be a proper option. Nevertheless, due to the heterogeneity of the studies, more clinical assessments are required to achieve more specific findings in this field.

Influence of one-wall remaining coronal tooth with resin abutment and fiber post on static and dynamic fracture resistance

The objective of this study was to determine the influence of height and thickness of the one wall remaining coronal tooth structure on the fracture resistance of an endodontically treated root with resin abutment build-up using resin composite and fiber-reinforced resin composite post. Static and dynamic fracture tests were performed by placing the remaining tooth wall on the tensile side and applying loads at an angle of 30° from the tooth axis. Superior static fracture resistance was observed when the wall remaining on the tooth had a height and thickness greater than 1.0 mm. The dynamic fatigue test showed high loading capacity or fracture resistance in specimens with large height and thickness. The dynamic fatigue test showed the influence of the remaining tooth structure on fracture resistance clearly. In conclusion, the static and dynamic fracture resistances increased with the height and thickness of the one wall remaining tooth structure.

Is a fiber post better than a metal post for the restoration of endodontically treated teeth? A systematic review and meta-analysis

OBJECTIVE

To evaluate systematically the evidence about the failure rates of endodontically treated teeth (ETT) restored with intraradicular metal posts (MPs) or fiber posts (FPs).

DATA

The review protocol was registered on PROSPERO (CRD42020189792). Eligibility criteria included randomized clinical trials (RCT) and prospective clinical trials (PCT) that compared the failures between FP and MP restorations for ETT. Meta-analyses were conducted for failure rates using fixed- and random-effects models. Subgroup and funnel plot analyses were performed.

SOURCES

Four electronic databases (MEDLINE/PubMed, Web of Science, Scopus, and Cochrane Library), manual, and grey literature were screened by two researchers independently for articles published until November 2020 without language or time restrictions. For the analysis of the risk of bias, the Cochrane collaboration tool and ROBINS-I were used. The certainty of the evidence was evaluated using GRADE.

STUDY SELECTION

Ten studies were included. A total of 704 participants with a mean age of 42.7 years with a total of 844 ETT were restored using 453 FPs and 391 MPs. The FPs presented similar failures to that with MPs (P=0.39; risk ratio [RR]:0.82; 95% confidence interval [CI]: 0.52 to 1.29). Subgroup analysis showed no significant differences between the FPs and MPs for the anterior region (P=0.60; RR:0.88; [CI]: 0.54 to 1.42), posterior region (P=0.52; RR:1.18; [CI]: 0.71 to 1.98), root fracture (P=0.44; RR:0.78; [CI]: 0.41 to 1.49), and debonding (P=0.56; RR:1.27; [CI]: 0.57 to 2.80). Additionally, FP showed similar failures compared with those of cast (P=0.36; RR:0.63; [CI]: 0.23 to 1.72) and prefabricated MPs (P=0.68; RR:0.90; [CI]: 0.54 to 1.50). The RCT and PCT studies revealed a low risk of bias for most of the domains. However, the certainty of evidence was considered low.

CONCLUSION

No evidence of difference was observed for failure rates between FPs, and MPs, independent of region and different MPs used in ETT. However, further well-conducted clinical studies with high-quality evidence are encouraged.

CLINICAL SIGNIFICANCE

Our results indicate that both retainer posts can be considered an adequate alternative in restoring ETT. Therefore, the choice of post (fiber or metal) could be based on dentist preference or individual characteristics of the patient as the failure rates for different posts are similar.

Influence of post type on periapical status: a prospective study in a Brazilian population

OBJECTIVES

This prospective study assessed the effect of post type used to restore endodontically treated teeth in the onset, progression, and remission of periapical lesions.

MATERIALS AND METHODS

One hundred and forty teeth (92 patients) were endodontically treated and received a glass fiber post or a cast metal post and a final restoration at a University Clinic by undergraduate students. All patients were followed up for a mean period of 5.1 ± 2.2 years. Periapical Index (PAI) was used for endodontic assessment. Two calibrated and blind examiners assessed the radiographs. The longevity of the endodontic treatment was analyzed using Kaplan-Meier statistics.

RESULTS

Of the included teeth, 67.1% received glass fiber posts while 32.9% received cast metal posts. There were 4 endodontic failures, two glass fiber posts with a PAI = 3 in the baseline and PAI = 4 in the last follow-up, and one PAI = 4 in baseline and last follow-up. One cast metal post-failure was PAI = 4 in the baseline and the last follow-up. After 9.4 years, the overall success rate of the endodontic treatment was 97.1% (p = 0.7).

CONCLUSIONS

The tested posts presented similar endodontic healing. Precautions taken during endodontic therapy, post cementation, and final restoration are more likely to be responsible for the success of endodontic treatment rather than a specific type of post. Clinical relevance The type of post is not related to the success of the endodontic treatment.

CAD/CAM Milled Glass Fiber Posts: Adaptation and Mechanical Behavior in Flared Root Canals

This study aimed to evaluate the cementation and mechanical behavior of flared root canals restored with CAD/CAM milled glass fiber post-and-core systems. Sixty-six endodontically treated human canines with a flared root canal were divided into three different groups according to the type of post: GPF received prefabricated posts; GREL received relined glass fiber posts, and GMILLED received CAD/CAM milled glass fiber posts. Cementation was performed with self-adhesive resin cement. The samples were submitted to x-ray microcomputed tomography analysis for the analysis of voids and gaps. The roots were sectioned and submitted to the push-out bond strength test. The load-to-fracture was evaluated in post-and-core systems. GMILLED presented lower void and lower gap volumes when compared to GPF and GREL. On the load-to-fracture test, GREL presented statistically significant higher values than GMILLED. GPF values had no statistically significant difference from the two other groups. On the push-out bond strength test, GPF presented statistically significant lower values when compared to GREL and GMILLED. The most common failure pattern was between dentin and cement in all groups. CAD/CAM milled glass fiber post-and-core systems presented an enhanced adaptation of glass fiber posts to flared root canal systems. Their results were comparable to relined posts in bond strength, while load-to-fracture-results for GMILLED were lower than those for GPF.

Better Glass-fiber Post Preservation in Teeth with Ferrule When Subjected to Chewing

OBJECTIVES

To evaluate the influence of ferrule effect and mechanical fatigue aging on glass-fiber post push-out bond strength (PBS) to root-canal dentin at different root thirds of premolars.

METHODS AND MATERIALS

Thirty-two sound maxillary premolar teeth were collected, and randomly assigned to two experimental groups (n=16): 'Remaining Dentin Ferrule' (RDF) = coronal crown cut 2.0 mm above the cementoenamel junction (CEJ); 'Without Dentin Ferrule' (WDF) = coronal crown cut at the cemento-enamel junction. Teeth were endodontically treated, post spaces were prepared up to 10.0-mm depth from CEJ, and glass-fiber posts were cemented using a dual-cure self-adhesive composite cement. Standardized cores were built using a light-cure composite, upon which tooth cores were prepared using a 1.5-mm taper ogival-end diamond bur. Crowns were handmade using self-cure acrylic resin and cemented using the aforementioned composite cement. Half of the specimens were subjected to 1,200,000 cycles of mechanical fatigue in a chewing simulator (F = 'Fatigue'), while the other half were stored in distilled water at 37°C for 1 week (C = 'Control'). All specimens were horizontally sectioned into 1.0-mm thick slices prior to PBS test; the failure modes were assessed using stereomicroscopy and scanning electron microscopy (SEM). Data were analyzed for each root third using two-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc test; frequency distribution was compared by Chi-square test (α=0.05) and post-hoc comparisons with Bonferroni.

RESULTS

The mean PBS in MPa (SD) were = RDF_F = 10.4 (2.9); WDF_F = 6.9 (1.7); RDF_C = 14.5 (2.7); WDF_C = 14.2 (2.9). Similar PBS were found for the root thirds. For all root thirds, significant differences were found for both the factors Dentin Ferrule and Fatigue, and their interaction (p<0.05). The lowest PBS was found for specimens without dentin ferrule subjected to chewing fatigue (p<0.001). Most failures occurred at the composite cement/dentin interface, followed by mixed and composite cement/glass-fiber post interfacial failures. There was a significant increase in mixed failures for the WDF_F group (p<0.001).

CONCLUSION

Absence of 2.0-mm remaining dentin ferrule in premolars resulted in a higher decrease of the glass-fiber posts' PBS to dentin after mechanical fatigue, irrespective of root third.

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.

The influence of customization of glass fiber posts on fracture strength and failure pattern: A systematic review and meta-analysis of preclinical ex-vivo studies

OBJECTIVE

To perform a systematic review of the literature focused to evaluate in vitro function of prefabricated fiber posts with and without customization by additional auxillary fiber posts and composite resin on the fracture strength of wide or enlarged canals and the failure pattern.

METHODS

Six databases were used as primary search sources (PubMed, Scopus, LILACS, SciELO, Science Direct, and Web of Science) and three databases (Open Grey, Open Thesis, and OATD) were used to partially capture the "grey literature". The research included laboratory studies that used human upper anterior teeth aiming to assess the fracture strength and failure pattern of different glass fiber post customizations by additional auxiliary fiber posts or composite resin. The search had no restriction of year, language, and publication status. The risk of bias of the studies was assessed from the criteria established in systematic reviews of laboratory studies. Standardized mean differences were calculated by comparing the mean fracture strengths of customized and non-customized posts. Pooled estimates were calculated by Glass' delta method using the random-effects model. Subtotal estimates were presented according to each type of relining procedure and an overall estimate was described considering all studies combined.

RESULTS

The search provided 2291 results, from which six met the eligibility criteria and were included in the qualitative assessment of the review. Only three studies presented a moderate risk of bias. The meta-analysis results showed that the use of auxiliary posts produced higher mean fracture strengths than non-customized posts (SMD = 2.21; 95%CI: 0.74; 3.68), and it was more effective than the use of composite resin to reline the posts.

CONCLUSION

Based on laboratories studies, even though has not been observed any difference to a statistically significant level on fracture strength and failure pattern of the customized and non-customized post, future studies should follow a standardized approach to implementation and reporting of data.

The Influence of Dentin Wall Thickness and Adhesive Surface in Post and Core Crown and Endocrown Restorations on Central and Lateral Incisors

CLINICAL RELEVANCE

Post and core crowns and endocrowns perform similarly on fracture strength, but endocrowns have more repairable fractures.

SUMMARY

The restoration of root filled teeth: a review of the clinical literature

Clinicians often face dilemmas regarding the most appropriate way to restore a tooth following root canal treatment. Whilst there is established consensus on the importance of the ferrule effect on the predictable restoration of root filled teeth, other factors, such as residual tooth volume, tooth location, number of proximal contacts, timing of the definitive restoration and the presence of cracks, have been reported to influence restoration and tooth survival. The continued evolution of dental materials and techniques, combined with a trend towards more conservative endodontic-restorative procedures, prompts re-evaluation of the scientific literature. The aim of this literature review was to provide an updated overview of the existing clinical literature relating to the restoration of root filled teeth. An electronic literature search of the PubMed, Ovid (via EMBASE) and MEDLINE (via EMBASE) databases up to July 2020 was performed to identify articles that related the survival of root filled teeth and/or restoration type. The following and other terms were searched: restoration, crown, onlay, root canal, root filled, post, clinical, survival, success. Wherever possible, only clinical studies were selected for the literature review. Full texts of the identified articles were independently screened by two reviewers according to pre-defined criteria. This review identifies the main clinical factors influencing the survival of teeth and restorations following root canal treatment in vivo and discusses the data related to specific restoration type on clinical survival.

Fracture load and shear stress of prefabricated glass fiber posts

Aim: This study evaluated the fracture load and pattern failure of different prefabricated glass fiber posts (GFPs) of the same diameter. Methods: Seventy-eight (n=13 for six groups) GFPs of 1.6 mm coronal diameter of different brands were evaluated— Exacto (Angelus), Power Post (BM4), White Post DC (FGM), HiRem (Overfibers), MAQ (Maquira), and SD (Supordont). The posts were subjected to fracture load testing (45° of inclination and 1 mm/min until fracture). Each factor (load (N) and shear stress (MPa)) was analyzed separately using one-way ANOVA followed by the Tukey test (α=0.05). Results: The type of failure was evaluated on a stereomicroscope (×10). The Power Post samples presented higher values of fracture load (p<0.001) followed by Maquira fiber post, White Post , HiRem, Superpost, and the Exacto posts. The failure pattern observed was intralaminar mode II in-plane shear, such as a failure occur parallel to fibers. Conclusion: Despite the same diameter of GFPs, the fracture load and shear resistance were brand-dependent.

Retrospective analysis of survival rates of post-and-cores in a dental school setting

STATEMENT OF PROBLEM

The clinical survival of different types of post-and-core systems requires assessment.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the clinical survival rate (CSR) of custom-fabricated cast metal and prefabricated (both metal- and fiber-reinforced composite resin post) post-and-cores as a function of patient- and restoration-related variables.

MATERIAL AND METHODS

A retrospective analysis was conducted on electronic charts indicating that these patients had received some type of post-and-core between January 2003 and January 2018. A total of 754 records were included in the analysis based on the inclusion criteria. Data were analyzed by using the Kaplan-Meier and Cox proportional hazards analysis.

RESULTS

Kaplan-Meier analysis demonstrated the mean survival time for each group to be 12.0 years for fiber-reinforced composite resin posts, 11.8 years for cast metal post-and-cores, and 10.2 years for prefabricated metal posts. Although the mean survival time differed by 1.8 years among groups, with prefabricated metal posts having a slightly higher risk of failure, this effect was not statistically significant (P=.067). The effect of post type also failed to reach significance when controlling for patient demographics and post position in a Cox proportional hazards analysis (P=.106). However, the Cox model did show that survival was associated with tooth position (P=.003), cement (P=.021), and type of restoration (P<.001).

CONCLUSIONS

Analysis showed no evidence that post-and-core survival was significantly associated with 3 types of post-and-cores (custom-fabricated metal, prefabricated metal, and prefabricated fiber-reinforced composite resin). The percentage of root in the bone, tooth position, cement, and type of restoration, however, were significantly associated with survival.

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.

Oval Versus Circular-Shaped Root Canals: Bond Strength Reached with Varying Post Techniques

Abstract The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey’s test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Pino de fibra de vidro anatômico: relato de caso

Introdução: Pinos pré-fabricados de fibra de vidro possuem boas propriedades mecânicas e estéticas. Porém, estes podem não se adaptar bem em canais amplos ou excessivamente cônicos, prejudicando sua retenção ao canal radicular. Uma alternativa para esta desvantagem é a utilização da técnica de pino anatômico. Objetivo: O objetivo do relato de caso foi apresentar a técnica de confecção de um pino fibra de vidro anatômico em dente anterior, com reduzido remanescente coronário e ampla embocadura do canal radicular. Relato de Caso: Paciente masculino, 49 anos, procurou atendimento odontológico com queixa da aparência estética de seus dentes anteriores superiores. Após remoção de uma coroa metalocerâmica e um pino-núcleo metálico fundido do elemento 12, foram confeccionados um pino de fibra de vidro anatômico, núcleo de preenchimento e coroa provisória. Foram realizadas as facetas em resina composta nos elementos 13, 11, 21, 22 e 23. Uma coroa de cerâmica reforçada por dissilicato de lítio (IPS e.max CAD, Ivoclar Vivadent) foi cimentada no elemento 12. Conclusões: Através da técnica pino de fibra de vidro anatômico, é possível reabilitar dentes anteriores tratados endodonticamente sem a utilização de pinos metálicos, apresentando bons resultados estéticos. Entretanto, uma condição oclusal dentro dos princípios de uma oclusão mutuamente protegida deve ser almejada para garantir longevidade da restauração.

Are fibre posts associated with the occurrence of prosthetic complications?

Data sourcesThe Pubmed, Evidence-Based Dentistry, BMJ Clinical Evidence, EmbaseDynamed, and www.opengrey.eu databases and manual search of reference lists.Study selectionRandomised clinical trials (RCTs) were accepted if they had: participants with no periodontal disease and teeth restored with SCs or FDPs and compared fibre posts and other prosthetic systems and evaluated the prosthetic complications with a minimum observational period of 36 months.Data extraction and synthesisTitles and abstracts were evaluated independently by two reviewers, any disagreement was discussed with a third reviewer. The agreement for the two reviewers was 97%. The quality and the risk of bias of the studies included was assessed following the Cochrane Handbook considering the domains of randomisation, sample size, inclusion and exclusion criteria, follow-up achieved, blinding, withdrawing and groups' compatibility for quality assessment, and for the risk of bias the domains evaluated were allocation concealment, blinding of outcome assessor and follow-up.ResultsThe database search yielded 4,230 records; after duplications removal, 3,670 records were reviewed independently by the authors, and four articles were chosen to include in the systematic review.The most frequently reported failures in the available studies were as follows: fibre post debonding, loss of retention of single crowns and marginal gaps. Less frequently, chippings and fractures were recorded in SCs. No studies about complications related to FDPs were found.The failure rate ranged from 0 to 28.2%.ConclusionsA correlation between the failure rates of fibre posts and the type of prosthetic restoration (SCs or FDPs ) cannot be found. Further RCTs are required to achieve evidence-based conclusions, particularly about the use of fibre posts with FDPs.

Methodological and Reporting Quality of Systematic Reviews and Meta-analyses in Endodontics

INTRODUCTION

The aim of this systematic review (SR) was to evaluate the quality of SRs and meta-analyses (MAs) in endodontics.

METHODS

A comprehensive literature search was conducted to identify relevant articles in the electronic databases from January 2000 to June 2017. Two reviewers independently assessed the articles for eligibility and data extraction. SRs and MAs on interventional studies with a minimum of 2 therapeutic strategies in endodontics were included in this SR. Methodologic and reporting quality were assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR) and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA), respectively. The interobserver reliability was calculated using the Cohen kappa statistic. Statistical analysis with the level of significance at P < .05 was performed using Kruskal-Wallis tests and simple linear regression analysis.

RESULTS

A total of 30 articles were selected for the current SR. Using AMSTAR, the item related to the scientific quality of studies used in conclusion was adhered by less than 40% of studies. Using PRISMA, 3 items were reported by less than 40% of studies, which were on objectives, protocol registration, and funding. No association was evident comparing the number of authors and country with quality. Statistical significance was observed when quality was compared among journals, with studies published as Cochrane reviews superior to those published in other journals. AMSTAR and PRISMA scores were significantly related.

CONCLUSIONS

SRs in endodontics showed variability in both methodologic and reporting quality.

Outcome of secondary root canal treatment filled with Thermafil: a 5-year follow-up of retrospective cohort study

OBJECTIVES

The aim of the present retrospective cohort study was to assess the 5-year outcome and survival of secondary root canal treatments (2°RCT), exploring the influence of pre-, intra-, and post-operative variables.

MATERIALS AND METHODS

One hundred thirty-two endodontically retreated teeth were radiographically and clinically re-examined after 5 years. 2°RCT had been performed during a Masters program following standardized protocols and filled with AH Plus/Thermafil (TF). Pre-, intra-, and post-operative data were collected. The 5-year outcome was blindly evaluated and categorized as healed/diseased on the basis of the periapical index. Bivariate analysis and chi-square test evaluated the association between outcome and 31 demographic/clinical parameters. Multilevel analysis was performed at both patient and tooth level. Statistical significance was calculated at 5% level.

RESULTS

At 5-year evaluation, survival rate was 80% with 7.5% lost for endodontic reasons. Eighty-three percent of the teeth were classified as healed. Multilevel analysis identified significant predictors of increased survival: female gender (p = 0.012), absence of a pre-operative metal post (p = 0.017), conservative apical preparation (diameter size < #35) (p = 0.039), teeth restored with a crown (p = 0.009), and final PAI (after 5 years) ≤ 2 (p = 0.001). Multilevel analysis identified as predictor healing: not being a smoker (p = 0.048) and conservative apical preparation < size #35 (p = 0.037).

CONCLUSIONS

Outcome of 2°RCT filled with Thermafil was successful at 5 years, showing a high rate of survived and healed teeth comparable to that reported previously for other obturation techniques.

CLINICAL RELEVANCE

Present findings confirm 2°RCT as a valid therapeutic option to retain natural teeth.