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

Evaluation of the accuracy of two full-digital versus half-digital techniques for post-and-core with different root canal entrance diameters

PURPOSE

With the advancement in digital technology, post-and-cores can be produced using full-digital techniques. This study aimed to evaluate the accuracy of two full-digital impression techniques for scanning the post space with different root canal entrance diameters using an intraoral scanner (IOS) (TRIOS 3) with and without a scan post, compared to the half-digital impression technique.

METHODS

Standard models of three intact teeth with varying root canal entrance diameters were prepared. Fifteen post-and-core designs per tooth were created using direct IOS and IOS with scan posts, with the half-digital technique as the control. All files were exported as standard tessellation language (STL) files, and the root mean square (RMS) deviations were analyzed between the experimental and control groups. Deviations were measured at standardized points across four regions: the occlusal external, occlusal internal, middle third, and apical third.

RESULTS

No significant differences in the overall RMS were observed among the different root canal entrance diameters (3 mm, 4 mm, and 5 mm) for direct IOS and IOS with scan posts (P > 0.05). However, an independent samples t-test revealed a significant difference (P < 0.05) in both trueness and precision between the two experimental groups, with IOS with scan posts consistently showing lower RMS values.

CONCLUSIONS

For post space lengths less than 7.4 mm in single-rooted teeth, both direct IOS and IOS with scan posts can serve as viable alternatives to half-digital techniques. However, in deeper areas, IOS with scan posts are recommended as alternatives to the half-digital technique.

Biomechanical performance of post-and-cores of polyetheretherketone and its composites

BACKGROUND

Polyetheretherketone (PEEK) and its fiber-reinforced composites have been indicated as ideal post-and-cores materials due to its mechanical properties. However, the laboratory evidences of post-and-cores restored with fiber-reinforced PEEK are lacking.

MATERIALS AND METHODS

A total of 120 extracted mandibular premolars were treated endodontically and divided into six groups restored with different post-and-core materials (N = 20): (1) prefabricated quartz fiber-reinforced composite (QFRC), (2) polymer-infiltrated ceramic (PIC), (3) cobalt chromium (CoCr), (4) PEEK, (5) 30% glass fiber-reinforced PEEK (GFR-PEEK), and (6) 30% carbon fiber-reinforced PEEK (CFR-PEEK). Stress distribution was analyzed by finite element analysis (FEA). Then, each group was then divided into two subgroups (n = 10): static loading test and fatigue loading test. The static failure load (SFL) was analyzed by one-way analysis of variance (ANOVA) with least-significant difference (LSD) multiple comparison tests. The fatigue failure load (FFL) and cycles for failure (CFF) were evaluated by Kaplan-Meier survival analysis (P < 0.05).

RESULTS

Groups PEEK, GFR-PEEK, and CFR-PEEK exhibited lower maximum peak principal stress and better stress distribution than Group CoCr. The SFL of Groups PEEK and QFRC did not differ from each other, and both were lower than those of Groups CoCr, GFR-PEEK, and CFR-PEEK. In the fatigue loading test, Group CoCr exhibited the best survival; however, with the progression of fatigue, the survival probabilities of Groups PEEK and its composites were close to that of Group CoCr. In all groups apart from Group CoCr, the rate of repairable failure modes was higher than that of irreparable ones.

CONCLUSIONS

Customized post-and-cores manufactured with PEEK and its fiber-reinforced composites showed superior biomechanical performance, making them potential alternatives for the restoration of massive tooth defects.

CLINICAL RELEVANCE

This study provides a theoretical basis for clinicians to select post-and-core materials for different root canal morphology residual roots and helps to reduce the occurrence of complications such as root fracture and post core debonding.

Mechanical Properties of PEEK Post-Cores Compared to Other Post-Cores: A Systematic Review and Meta-Analysis

Recently, polyetherpolyetherketone (PEEK) has gained popularity as a dental biomaterial. However, there is a lack of consensus on its potential use as an endodontic post-core material. The aim of this review was to systematically critique and synthesize the evidence on PEEK-based post-cores in comparison to other materials. An electronic search was conducted on PubMed, Medline, Embase, ISI Web of Science, Ovid, Cochrane, and ClinicalTrials.Gov using relevant keywords. Seven in vitro studies were included in this review. Meta-analysis of fracture resistance was carried out on results reported in three studies. Overall, in most of the studies, PEEK post-cores performed similar to glass-fiber post-cores. The meta-analysis revealed no significant difference between the fracture strengths of PEEK and glass-fiber post-cores. However, in most studies, several sources of bias were identified. Within the limitations of this review, it may be concluded that mechanical and physical properties of PEEK posts are similar to those of glass-fiber post-cores. Nonetheless, long-term clinical studies are required to translate these conclusions into clinical practice.

Randomized controlled trial comparing glass-fiber versus metal posts in single-crowned teeth: 15 Year follow-up

OBJECTIVE

This randomized controlled trial compared the 15-year clinical success and survival rate of endodontically treated teeth restored with glass-fiber or metal posts.

METHODS

131 patients in need of 182 post and single-crown restorations were included. Teeth were randomly assigned to the control group (metal post, Parapost XT, Coltène) or test group (glass-fiber post). Teeth in the test group were further divided based on the size and shape of the root canal (RC). Teeth with a small RC were restored with prefabricated glass-fiber posts (Parapost Fiberlux, Coltène) and teeth with a wide oval canal with custom-made glass-fiber posts (Everstick, StickTech). Patients had follow-up appointments at 3, 5 and 15 years. Success (original post present) and survival (present after intervention) probability lifetime curves, corrected for clustering, were calculated (Kaplan-Meier).

RESULTS

The mean follow-up time was 179.6 ± 7 months, and the recall rate was 91.6 %. Success rate was 48.0 % for metal posts, 59.2 % for prefabricated glass-fiber posts and 49.5 % for custom glass-fiber posts. Survival rate was 53.6 % for metal posts, 68.5 % for prefab glass-fiber posts and 55.3 % for custom glass-fiber posts. No statistically significant effect of post material was observed. There was, however, a trend towards better success/survival for teeth with prefabricated glass-fiber posts. Teeth with metal posts failed more frequently due to root fracture than teeth with glass-fiber posts.

CONCLUSIONS

There was a trend towards better clinical success and survival rate for teeth restored with glass-fiber posts, even though post material had no statistically significant effect on the clinical outcome.

CLINICAL SIGNIFICANCE

After 15-years, teeth restored with glass-fiber posts tended towards better clinical success and survival than teeth restored with gold-alloy posts. The difference in clinical outcome was, however, not statistically significant, probably due to a low effect size of the post material on success and survival.

Stress Evaluation in Endodontically Treated Virtual Teeth Restored with Composite Fillings and Cast or Fiberglass Posts-A Finite Element Analysis

Background/Objectives: Among the complications of endodontic treatment, root fractures are the most severe and may require tooth extraction. The objective of this study was to develop virtual models of mandibular molars with different endodontic restorations to assess the stress distribution in tooth structures based on the type of corono-radicular restoration, compared with the model of an intact molar. Methods: Four virtual models of a mandibular molar were created: (1) an intact molar with preserved enamel, dentin, dental pulp and cementum; (2) an endodontically treated molar restored with a composite filling; (3) a molar restored with a fiberglass post and monolithic zirconia crown; (4) a molar restored with a metal cast post and monolithic zirconia crown. External force loads from 0 to 800 N were simulated using Finite Element Method (FEM). Results: The highest displacement, strain and stress values were observed in the molar restored with a composite filling, whereas the lowest values were recorded in the molar restored with a fiberglass post and zirconia crown. Critical stresses were primarily concentrated on the pulp chamber floor. Conclusions: The pulp chamber floor was identified as the most vulnerable area for fracture. This underscores the importance of preserving tooth structure to enhance the strength and durability of molars throughout and beyond endodontic treatment.

Robot-Assisted Endodontic Retreatment: A Case Report with Clinical Considerations

Fiber posts present significant challenges for nonsurgical endodontic retreatment, as improper removal may result in iatrogenic root perforation or even root fracture. Recently, robotic technology has attracted considerable attention in dentistry and active dental robotic (ADR) systems can perform procedures based on preset instructions, minimizing reliance on the dentist's experience. This case report describes the application of an ADR system for fiber post removal through an existing zirconia crown. A 26-year-old female was diagnosed with previously treated, symptomatic apical periodontitis of the mandibular left second premolar. Based on cone-beam computed tomography (CBCT) and intraoral scanning, the ADR system was used to achieve precise fiber post removal through a zirconia crown with minimally invasive coronal access under rubber dam isolation. The robotic arm executed flexible pumping motions to simulate the hand movements of dentists. This was achieved by establishing preset force and distance thresholds tailored to the characteristics of the materials being drilled. Residual gutta-percha was removed, followed by canal preparation and obturation. The tooth was then restored with a fiber post and composite resin. At the 2.5-month follow-up, the patient was completely asymptomatic, and the radiograph displayed evidence of periradicular healing. In this case, robotic technology proved effective and feasible for the endodontic retreatment of a mandibular second premolar, suggesting its potential for similar applications in other teeth where there is adequate inter-arch space. Further research is needed to simplify procedures for robot-assisted endodontic retreatment.

Aging Effect on Push-Out Bond Strength of Six Resin Cements: An In Vitro Study

The number of resin cements marketed for fiber post cementation has increased significantly. This study compared the push-out bond strength (PBS) of self-adhesive and universal resin cements used to lute fiber posts at 24 h and after 6 months of aging in artificial saliva. Fiber posts were luted to eighty human roots endodontically treated with four self-adhesive/one-step resin cements, with one of them also used in combination with its appropriate tooth primer; one universal resin cement, applied as one-step or together with its corresponding universal adhesive (multi-step); and one adhesive/multi-step resin cement, as a control. After storage (24 h or 6 months), the interfaces were subjected to PBS tests and the data were analyzed by two-way ANOVA and Tukey and Student's t-tests (p < 0.05 defined as statistical significance). The results showed that Scotchbond Universal Plus + RelyX Universal attained statistically higher values at 24 h and 6 months. At 24 h, all resin cements yielded similar PBS to root dentin, while at 6 months, NormoCem obtained the lowest PBS. Storage for 6 months significantly decreased PBS for NormoCem and Multilink Automix. Root section did not influence PBS regardless of storage time. It was concluded that PBS is resin cement dependent. The universal resin cement, RelyX Universal, applied in combination with Scotchbond Universal Plus adhesive, obtained a higher and more stable PBS than the other resin cements tested.

The accuracy of direct digital impressions of post spaces with different diameters and depths scanned by a wireless intraoral scanner

OBJECTIVES

To assess the accuracy of a wireless intraoral scanner (IOS) in scanning post spaces with different diameters and depths.

METHODS

Six maxillary central incisors underwent endodontic treatment and tooth preparation. Post space preparation was performed using a #4 or #6 post drill to depths of 6, 8, and 10 mm, respectively. Direct digital impressions of the post spaces were scanned using an IOS (Trios 5, 3Shape, Copenhagen, Denmark) ten times as test data. Conventional impressions were also taken and subsequently scanned using a laboratory scanner to serve as reference data. The accuracy of the test data was evaluated through both 3D and 2D comparisons against the reference data. Statistical analysis was performed using analysis of variance (α=0.05).

RESULTS

As post space depth increased or diameter decreased, 3D root mean square (RMS) values increased, ranging from 65.7 μm to 82.8 μm (p < 0.001), while the proportion of green region (indicating a deviation within 0.1 mm) decreased from 90.05 % to 76.38 % (p < 0.001). 2D RMS values gradually decreased from the cervical to the apical region. Except for the apical region in the #4 drill group with a 10 mm depth, all 3D and 2D RMS values remained below 100 μm. Furthermore, only the post space with a 10 mm depth in the #4 drill group exhibited a proportion of green region <80 %.

CONCLUSIONS

The accuracy of the wireless IOS in post space scanning was significantly affected by both depth and diameter, and decreased with increasing depth or decreasing diameter. Furthermore, the accuracy diminished as the scan approached the apical region.

CLINICAL SIGNIFICANCE

When the depth of post space prepared with a 1.9 mm diameter drill is ≤8 mm or when prepared with a 2.25 mm diameter drill is ≤10 mm, Trios 5 is suitable for direct digital impressions.

Fracture resistance, 3-dimensional finite element analysis, and safety factors for five post-and-core restorations with crowns placed in the noncircular-shaped canals of premolars

STATEMENT OF PROBLEM

Restoring endodontically treated premolars with noncircular canals presents a significant challenge.

PURPOSE

The purpose of this study was to compare the in vitro fracture resistance and the finite element computational calculation-based stress and safety factor of noncircular-shaped, endodontically treated premolars restored with 5 different prefabricated and custom computer-aided design and computer-aided manufactured post-and-core systems.

MATERIAL AND METHODS

Fifty single-rooted oval-shaped canal maxillary premolars were endodontically treated and post spaces were prepared. The specimens were divided into 5 categories on the basis of the post-and-core system used: Group CN composite resin core without a post, Group CF prefabricated fiber-reinforced composite resin post and composite resin core, Group IC interpenetrating phase composite post-and-core, Group LS lithium disilicate post-and-core, and Group ZR zirconia post-and-core. Lithium disilicate crowns were fabricated and cemented on the 5 different post-and-core systems and subjected to a fracture resistance test using a spherical indenter with static loading. Differences in fracture resistance were evaluated using a 1-way analysis of variance (ANOVA) (α=.05). The 3-dimensional finite element method was used to determine the von Mises stress and safety factors, defined as the ratio of the material's strength to the von Mises stress experienced, within different compartments of the restored tooth model.

RESULTS

In the in vitro fracture resistance test, the mean ±standard deviation fracture loads of the 5 groups were 2144 ±515 N, 1801 ±600 N, 1690 ±312 N, 1612 ±545 N, and 1487 ±600 N, respectively and were statistically similar (P=.078). All specimens within the ZR group exhibited restorable fractures. In contrast, only 30% of the CN group specimens showed restorable fractures. The incidence of restorable fractures in the CF, IC, and LS groups was 70%, 80%, and 70%, respectively. Although all groups showed similar maximum von Mises stress and stress distribution, safety factors in the models varied significantly. The ceramic crown was the weakest component in the LS and ZR groups, with much lower safety factors than dentin and post-and-core regions. Additionally, the CN group's wider dentin area had a demonstrably lower safety factor.

CONCLUSIONS

Endodontically treated noncircular-shaped canal premolars showed minimal effect on fracture resistance regardless of post type. However, for teeth with sufficient ferrule, using any post-and-core system significantly reduced the incidence of nonrestorable fractures compared with just a coronal foundation restoration, with custom zirconia offering the potential of achieving a restorable outcome after fracture.

Survival time and success rates of customized prefabricated metal posts: A retrospective study

STATEMENT OF PROBLEM

The choice of post type is still a controversial issue in dental practice. Furthermore, studies regarding the long-term survival and success of customized prefabricated posts are lacking.

PURPOSE

The purpose of this retrospective study was to assess the longevity of prefabricated metal posts customized to conform to the root canal.

MATERIAL AND METHODS

Data obtained from the records of patients who received a customized titanium or stainless-steel post at a private dental practice between July 1998 and March 2022 were analyzed. The prefabricated posts were customized by grinding the threads, reducing their length, and tapering them to fit into the existing canals. The relation between survival time and type of tooth and coronal restoration was searched. The Kaplan-Meier test was used for survival time and Cox regression to evaluate factors associated with survival (α=.05). The data were also analyzed for 5-year time intervals.

RESULTS

A total of 1791 posts in 1072 patients were available for the study. The mean overall survival time of the posts was 17.33 years. The mean survival time with regard to the coronal restoration was 15.22 years for direct composite resin restorations, 17.21 years for metal-ceramic crowns, 14.94 years for fixed partial dentures, and 12.63 years for removable partial dentures. The survival time for anterior teeth was 13.16 years and 17.53 years for posterior teeth. The success rate of the posts was 97.5%.

CONCLUSIONS

This retrospective study of customized prefabricated metal posts resulted in a 17-year post survival time and a success rate of 97.5%.

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 post material and ferrule thickness on the fracture resistance of endodontically treated premolars: A laboratory study

STATEMENT OF PROBLEM

The influence of the ferrule thickness and post materials on the fracture resistance of endodontically treated teeth remains unclear.

PURPOSE

The purpose of this laboratory study was to evaluate the influence of post material and ferrule thickness on the fracture resistance of endodontically treated mandibular premolars.

MATERIAL AND METHODS

Sixty-four extracted and endodontically treated mandibular first premolars were used and divided into 4 test groups (n=16) depending on the ferrule thickness: F-0: without a ferrule, F-0.5: with a 0.5-mm ferrule thickness, F-1: with a 1-mm ferrule thickness, and F-1.5: with a 1.5-mm ferrule thickness. In groups with ferrules, the height ranged from 2 mm buccally/lingually to 1 mm proximally. Teeth in subgroups (n=8) were restored with either prefabricated glass fiber (FF) or titanium posts (FT) (ISO size 70 and length of 7.5 mm) and then adhesively restored with composite resin foundation materials. After foundation procedures, each specimen was restored with a cobalt chromium crown which was cemented with glass ionomer cement. All specimens were subjected to dynamic loading in a masticatory simulator for 1 200 000 loading cycles with a nominal load of 5 Kg at 1.2 Hz and simultaneous thermocycling (5 to 55 °C). Specimens were then quasistatically loaded at 30 degrees in a universal testing machine until fracture. Fracture loads were analyzed by using 2-way ANOVA followed by the Tukey honestly significant difference test (α=.05).

RESULTS

Fracture loads ranged from 610 ±45 N (no ferrule - glass fiber post) to 1216 ±169 N (1.5 mm ferrule thickness - glass fiber post). A statistically significant increase in fracture resistance was observed with increasing ferrule thickness (P<.001). However, post materials did not show a statistically significant influence (P=.977).

CONCLUSIONS

Under the conditions of this laboratory study, increasing the ferrule thickness had a significant effect on the fracture resistance of endodontically treated teeth after thermomechanical fatigue, irrespective of post materials.

Fiberglass posts reduced fractures in endodontically treated teeth restored with veneers: a case-control study

This study aimed to evaluate the effects of fiberglass posts on fracture behavior in endodontically treated teeth (ETT) restored with composite veneers. Adult patients who had endodontically treated anterior teeth restored with composite veneers, with or without fiberglass posts, were divided into the case (with fractured teeth) and control (without fractured teeth) groups. All fracture patterns were sorted by a 6-point scoring system: 0, no fracture; 1, veneer buccal fracture; 2, incisal edge fracture; 3, coronal middle-third fracture; 4, coronal cervical fracture; 5, coronal and root fracture; and 6, root fracture. The odds ratio was calculated concerning the outcome (fracture) and exposed factor (post presence). Fracture patterns were analyzed by the Mann-Whitney and Fisher exact tests, with a significance level of 95%. Of the 89 ETT restored with composite veneers (31 with posts; 58 without posts), 30 were fractured. The odds ratio revealed a reduction in fracture risk to 34% compared with ETT without posts. Teeth without posts fractured more frequently, showing more complex fracture patterns. In conclusion, fiberglass posts decreased the risk of fractures in ETT restored with composite veneers.

Clinical Acceptance of Digitally Produced Zirconia and Metal Post and Cores, Based on the Impression Method

BACKGROUND

The existing literature predominantly examines post and core assessments post-cementation, neglecting the critical pre-cementation phase. Research on the clinical acceptance of dental posts received from dental laboratories before cementation is notably lacking. This study investigates the percentage of zirconia and metal dental posts that are deemed suitable for cementation by clinicians, among the total received from the dental laboratory. Additionally, it aims to examine whether this percentage varies based on the type of impression made by the clinician: digital impression versus conventional impression.

METHODS

This article introduces the application of computer-aided design-computer-aided manufacturing (CAD-CAM) technology for manufacturing customized zirconia and Cobalt-Chromium (Co-Cr) post and cores. Intraoral scanning is employed to capture the canal anatomy. In contrast to the traditional casting process, a three-dimensional (3D) metal printer machine is utilized to 3D print the metal post and core from Co-Cr, resulting in enhanced toughness and superior adaptability to the canal. Two null hypotheses were formulated, investigating the clinical acceptance of zirconia and metal posts obtained through traditional versus digital impressions.

RESULTS

Among 577 post and cores, 95% of metal posts from both impression methods received clinical approval. However, for zirconia posts, a significantly higher acceptance rate (95% versus 88%) was observed for those from traditional impressions. The Chi-squared test yielded a p-value < 0.05, underscoring the clinical superiority of conventionally obtained zirconia posts and supporting the null hypothesis for metal posts.

CONCLUSIONS

A significantly higher acceptance rate is apparent among zirconia post and cores manufactured through conventional impressions, in contrast to zirconia post and cores produced via digital impressions. No statistically significant difference was identified between metal post and cores obtained through digital impressions and those acquired through conventional impressions.

Zirconium Oxide as a Novel Material for Post-Endodontically Treated Teeth: Comparative Fracture Behavior of 3D-Printed Cobalt-Chromium, Milled Zirconium Oxide, and Quartz Fiber Posts

This study evaluates the mechanical properties of materials used in the post-endodontic restoration of root-treated teeth and examines their performance under stress to provide insights for material selection in clinical applications. Particular attention is given to zirconium oxide, which demonstrates promising characteristics due to its esthetic color and favorable material properties, positioning it as a potential material for future use in post-endodontic treatments. Three materials-prefabricated quartz fiber-reinforced composite, milled zirconium oxide, and additively manufactured cobalt-chromium-were evaluated using compressive-deflection tests. The specimens were subjected to a 45° compressive load extending 5 mm from a metal core. Their mechanical properties were analyzed using one-way ANOVA and Tukey's post hoc test. Significant differences were observed among the materials. Quartz fiber posts, with the lowest force resistance, buckled at lower loads (143.3 ± 9.9 N), while zirconia posts failed in a brittle manner at higher forces (246.1 ± 97.2 N). Cobalt-chromium posts demonstrated the highest maximal force (323.2 ± 10.5 N, p < 0.001) and, unlike the other materials, bent rather than fractured. The failure patterns of the tested materials underscore the importance of careful material selection when restoring root-treated teeth. Despite displaying distinct fracture characteristics, zirconium oxide, due to its color, rigidity, and hardness, stands out as a promising material for future dental applications. Further research through randomized clinical trials is recommended to refine treatment approaches and optimize clinical outcomes.

Clinical and laboratorial performance of rehabilitation of endodontically treated teeth: A systematic review

OBJECTIVE

This systematic review aimed to analyze the clinical (survival rate, failure risk, or fracture) and laboratory performance (fracture mode or failure) of rehabilitations of endodontically treated teeth, with and without posts.

MATERIALS AND METHODS

A systematic search was conducted in the Pubmed, Scopus, Web of Science, Embase, Cochrane Library, and OpenGrey databases up to March 2023, according to PRISMA guidelines. In vitro and clinical studies that compared the clinical and laboratory performance of endodontically treated teeth with and without intraradicular posts were included. Studies selection, data extraction, and risk of bias analysis were performed.

RESULTS

Thirty-one in vitro and 7 clinical studies were included. For in vitro studies, fiberglass post (n = 24) was the most mentioned. The follow-up time of the clinical studies ranged from 1 to 17 years, with the fiber-reinforced composite post (n = 3) being the most evaluated, and only failure risk proved to be more favorable for using intraradicular posts.

CONCLUSION

Rehabilitations of endodontically treated teeth with and without intraradicular retainers showed no difference in fracture resistance and failure mode, evaluated by in vitro studies. Clinical studies showed no difference in survival rate, but failure risk proved to be more favorable for the use of posts.

CLINICAL SIGNIFICANCE

This analysis revealed significant variability between results, however, most laboratory and clinical studies revealed no difference with using the post. Furthermore, it is important to emphasize the need to evaluate the coronary remnant and the general characteristics of the tooth in each situation.

The role of intraoral scanning in the fully digital workflow for post and core restorations: A scoping review

OBJECTIVE

This scoping review aimed to map the literature on the utilization of intraoral scanners (IOS) in fabricating post and core restorations.

DATA

The study protocol is available at https://osf.io/ja9xh/. This scoping review followed Joanna Briggs Institute guidelines, and reporting was based on the checklist proposed by PRISMA-ScR.

SOURCES

Searches were conducted in PubMed/MEDLINE, Web of Science, Scopus, and grey literature up to August 2023.

RESULTS

A total of 455 studies were identified. After screening, 16 studies were deemed suitable for scoping review. Of these, 13 were in vitro studies, two were case reports, and one was a clinical study. Different IOS systems for scanning post spaces were evaluated, with Trios being most prevalent, followed by Prismescan. While most studies did not use any intraoral scanning devices, five studies reported the use of scan posts. Results regarding retention favored fully digital workflows. However, results about the adaptation and accuracy varied between included studies, highlighting the importance of standardized approaches. Future clinical studies should encompass variations in IOS systems, post space depths, scanner depth of field, light conditions, scan post utilization, operator experience, scanning time and strategy, and direct comparison with conventional techniques.

CONCLUSION

IOS is increasingly important in capturing digital impressions for post spaces and provides valuable insights for clinicians and researchers. Although included studies, primarily in vitro, demonstrated promising results for the utilization of IOS systems in fully digital workflows for post and core restorations, further well-conducted studies, particularly clinical trials, are recommended due to data heterogeneity and limitations.

CLINICAL SIGNIFICANCE

This mapping highlights the potential of modern IOS in fully digital workflows for post and core restorations. Despite promising results, challenges related to different variables associated with IOS require careful consideration. Standardization and additional clinical validation are essential for optimize IOS benefits in post and core restorations.

Advanced Material Strategy for Restoring Damaged Endodontically Treated Teeth: A Comprehensive Review

The restoration of endodontically treated teeth (ETT) remains a significant challenge in modern dentistry. These teeth often suffer from substantial structural damage due to both the original pathology and the invasive nature of endodontic procedures. Consequently, ETT are more susceptible to fractures compared to vital teeth, necessitating restorative strategies that can effectively restore both function and aesthetics while minimizing the risk of failure. In recent years, advances in adhesive dentistry and the development of high-strength ceramics have further expanded the restorative options for ETT. Bonded restorations have gained popularity as they preserve more tooth structure and enhance the overall strenght of the tooth-restoration complex. The choice of restorative material and technique is influenced by numerous factors, including the amount of remaining tooth structure, the functional requirements of the tooth, and the aesthetic demands of the patient. Despite the plethora of available materials and techniques, the optimal approach to restoring ETT remains a topic of ongoing research and debate. In this comprehensive review, the current state of and recent advances in restoring damaged endodontically treated teeth are explored. Numerous therapeutic options exist, involving a wide range of materials. This article aims to present the biomaterial advancements of the past decade and their applications, offering alternative approaches to treating damaged ETT with the goal of prolonging their retention on the dental arch and serving as a valuable resource for dental practitioners who face this issue daily.

Restoration of teeth lacking complete ferrules using cast precious metal alloy post-and-cores and knife-edged crowns: A retrospective clinical study

STATEMENT OF PROBLEM

While the presence of a ferrule has been reported to be essential for post-and-core restorations, many extensively damaged teeth lack complete ferrules. The outcome of post-and-core restorations for these teeth remains uncertain.

PURPOSE

The purpose of this retrospective clinical study was to assess the outcome of cast alloy post-and-cores and knife-edged crowns for the restoration of teeth lacking complete ferrules.

MATERIAL AND METHODS

A total of 106 participants with endodontically treated teeth with 2 or fewer walls with ferrules who had received cast precious metal alloy post-and-cores along with knife-edged crowns between 2013 and 2022 were recalled for a clinical examination. The minimum follow-up time was 5 months after restoration, and restoration failure and the periodontal status difference between restored teeth and reference teeth were determined. Kaplan-Meier analysis was performed to obtain success curves. The influence of age, sex, jaw position, tooth type, and antagonistic dentition upon the success function was analyzed with the log-rank or Breslow test (α=.05).

RESULTS

A total of 100 participants with 130 restorations were studied. The success rate of the restorations was 93.85% in a mean ±standard deviation period of 48.3 ±26.1 months. The estimated 5-year cumulative success probability was 91.61%. No significant effect on the success of restorations was found regarding age, sex, jaw position, tooth type, or antagonistic dentition (P>.05). The main failure types were post debonding, root fracture, and apical periodontitis. No statistical difference in tooth mobility (Z=-1.265, P=.206) was found between the restored and the reference teeth, but the plaque index and calculus index of the restored teeth were significantly lower than of the reference teeth (Z=-7.216, P<.001; Z=-7.044, P<.001). Teeth that had received cast post-and-cores and knife-edged crowns were found to have no significant correlation with periodontal disease (χ²=1.131, P=.288) or bleeding on probing (χ²=3.436, P=.064).

CONCLUSIONS

The clinical outcomes for the restoration of teeth with 2 or fewer walls with ferrules using cast precious metal alloy post-and-cores and knife-edged crowns were favorable, exhibiting a high 5-year cumulative success probability and no increased periodontal health risk.

Factors influencing the clinical performance of the restoration of endodontically treated teeth: An assessment of systematic reviews of clinical studies

STATEMENT OF PROBLEM

How best to restore endodontically treated teeth is still unclear because many types of material and techniques are involved.

PURPOSE

The purpose of this overview of systematic reviews of clinical studies was to assess the available evidence-based literature on the influence of associated clinical factors on the clinical performance (survival, failure rate, or success) of restored endodontically treated teeth.

MATERIAL AND METHODS

PubMed, Scopus, and Web of Science were searched from inception until September 27, 2021, to identify systematic reviews. Two reviewers independently screened titles, abstracts, and full-text articles, and each reviewer extracted the data of half of the included studies. A single reviewer with an independent verifier completed the quality appraisal. A descriptive analysis of the collected data was made.

RESULTS

A total of 36 systematic reviews fulfilled the inclusion criteria. The factors most assessed were the type of coronal restorative technique (n=22) and type of post (n=22). The results indicated that metal and fiber posts seem to present similar clinical performance, 1-piece endodontic crowns could be a suitable restorative option, there is no evidence to confirm whether single crowns are better or worse than direct restoration, the maintenance of the coronal structure is a fundamental factor, and the ferrule effect is still a controversial topic. Most of the studies (n=30, 81%) presented a final Grading of Recommendations, Assessment, Development and Evaluations (GRADE) rating of "critically low."

CONCLUSIONS

The post type does not appear to influence the clinical performance of restored endodontically treated teeth. However, conclusive evidence to suggest how different materials or techniques for restoring coronal tooth structure affect the clinical performance of such restorations, as well as the impact of the ferrule effect, is still lacking.

Push-Out Bond Strength of Glass Fiber Endodontic Posts with Different Diameters

(1) Background: The retention of intraradicular posts is an important factor for the prognosis of endodontically treated teeth. The purpose of this study was to evaluate the push-out bond strength (PBS) of the posts relating to their diameter and region of the root. (2) Methods: A total of 40 premolar teeth (decoronated and root canal-filled) were divided into four groups (n = 10). After post-space preparation, different sizes (1.0, 1.2, 1.5, and 2.0 mm) of glass fiber posts were luted with resin cement into the root canals. After placement, 2 mm thick slices were cut from the roots according to their apical, middle, and coronal regions (n = 116). Push-out tests were carried out in a universal testing machine on each slice. A statistical evaluation of the data was applied. (3) Results: When comparing the diameter, the 2.0 mm posts had the highest PBS (111.99 ± 10.40 N), while the 1.0 mm posts had the lowest PBS (99.98 ± 8.05 N). Divided by the surface of the bonded area, the average PBS value was the highest for the 1.0 mm posts (18.20 ± 1.67 MPa) and the lowest for the 2.0 mm posts (12.08 ± 1.05 MPa). (4) Conclusions: Within the limitations of the study, when comparing the regions of the roots, no significant differences were found among the PBS values of the three regions (p = 0.219). When comparing the diameters, significant differences were shown between the PBS values of the four groups (p = 0.023 and p = 0.003, respectively).

The Outcomes of Endodontically Treated Teeth Restored with Custom-Made Cast Post-and-Core Restorations: A Retrospective Cohort Study

INTRODUCTION

Custom-made cast post-and-core (CMCPC) restorations have long been used to restore structurally deficient endodontically treated teeth (ETT). However, the evidence regarding their impact on the outcomes of ETT is largely inconclusive. This study evaluated the long-term treatment outcome of ETT restored with CMCPC.

METHODS

This retrospective cohort study examined the dental records of patients that received CMCPC at a specialty private practice in Toronto, Canada between 1999 and 2021. The proportion of ETT with complete periapical healing and those that survived were estimated, and prognostic factors were investigated using multiple logistic and Cox regression analyses respectively (P < .05).

RESULTS

A total of 500 and 1000 teeth met periapical healing and survival criteria, respectively. The periapical healing rate was 88.8% and was associated with the presence of baseline periapical radiolucency [odds ratio = 0.1; 95% confidence interval (CI), 0.05-0.2; P < .001]. The survival after a median follow-up time of 52.9 months (interquartile range: 26.5-99.4) was 90.1% and was associated with <75% of root length in bone [hazard ratio (HR) = 2.6; 95% CI, 1.0-6.6; P = .033], type and quality of final restoration (HR = 2.09; 95% CI, 1.1-3.9; P = .020; HR = 2.3; 95% CI, 1.2-4.5; P = .008, respectively), and the presence of periapical radiolucency at the latest recall (HR = 3.2; 95% CI, 1.7-6.3; P < .001).

CONCLUSIONS

The outcome of ETT restored with CMCPC was favorable. CMCPC may be regarded as a viable restorative option for structurally deficient ETT.

Internal adaptation and mechanical properties of CAD/CAM glass fiber post-cores in molars: An in vitro study

OBJECTIVE

The purpose of this in vitro study was to evaluate the internal adaptation, fracture resistance, and fracture pattern of the residual roots and crowns of molars restored with computer-aided design/computer-aided manufacturing (CAD/CAM) glass fiber post-cores, and compare them with three other post-core restorations.

MATERIALS AND METHODS

We selected 32 extracted maxillary first molars and divided them into four groups according to the post-core system: traditional casting titanium (Ti) post-cores (TC group); Ti post-cores fabricated with selective laser melting (SLM group); CAD/CAM glass fiber post-cores of the split type (CCS group); and prefabricated glass fiber posts and composite resin cores (PF group). The internal adaptation was analyzed with microcomputed tomography. Teeth were restored with monolithic zirconia crowns and subjected to thermocycling and cyclic loading. A load was applied consistently along the long axis of the tooth until fracture to record the fracture resistance and pattern. For the statistical analysis, one- and two-way analyses of variance, Tukey's post hoc and chi-square tests were performed to compare the differences among the groups.

RESULTS

The CCS, TC, and SLM groups exhibited similar internal adaptations across all sections (P < 0.05). The FP group showed good fit with the root canals in the apical and middle sections but a poor fit with those in the cervical section. The fracture resistance was higher in the CCS, TC, and SLM groups compared to the PF group (P < 0.05). The proportions of restorable fractures in the CCS and PF groups were 62.5% and 50%, respectively. Unrestorable fractures were more frequent in the TC and SLM groups at frequencies of 100% and 87.5%, respectively.

CONCLUSION

The internal adaptation and fracture resistance of the CCS group were similar to those of the TC and SLM groups, and the fracture pattern was mostly restorable, thus meeting the clinical requirements for molar post-core restorations.

CLINICAL SIGNIFICANCE

CCS can be used to restore residual roots and crowns of molars and exhibit high efficacy in terms of adaptability and mechanical properties. More studies are required to evaluate the effectiveness of CCS.

Assessment of biomechanical behavior of immature non-vital incisors with various treatment modalities by means of three-dimensional quasi-static finite element analysis

The objectives of this study were to evaluate the stress distribution and risk of fracture of a non-vital immature maxillary central incisor subjected to various clinical procedures using finite element analysis (FEA). A three-dimensional model of an immature central incisor was developed, from which six main models were designed: untreated immature tooth (C), standard apical plug (AP), resin composite (RC), glass-fibre post (GFP), regeneration procedure (RET), and regeneration with induced root maturation (RRM). Mineral trioxide aggregate (MTA) or Biodentine® were used as an apical or coronal plug. All models simulated masticatory forces in a quasi-static approach with an oblique force of 240 Newton at a 120° to the longitudinal tooth axis. The maximum principal stress, maximum shear stress, risk of fracture, and the strengthening percentage were evaluated. The mean maximum principal stress values were highest in model C [90.3 MPa (SD = 4.4)] and lowest in the GFP models treated with either MTA and Biodentine®; 64.1 (SD = 1.7) and 64.0 (SD = 1.6) MPa, respectively. Regarding the shear stress values, the dentine tooth structure in model C [14.4 MPa (SD = 0.8)] and GFP models [15.4 MPa (SD = 1.1)] reported significantly higher maximum shear stress values compared to other tested models (p < 0.001), while no significant differences were reported between the other models (p > 0.05). No significant differences between MTA and Biodentine® regarding maximum principal stress and maximum shear stress values for each tested model (p > 0.05). A maximum strain value of 4.07E-03 and maximum displacement magnitude of 0.128 mm was recorded in model C. In terms of strengthening percentage, the GFP models were associated with the highest increase (22%). The use of a GFP improved the biomechanical performance and resulted in a lower risk of fracture of a non-vital immature maxillary central incisor in a FEA model.

Conventional cast vs. CAD/CAM post and core in a fully digital chairside workflow - An in vivo comparative study of accuracy of fit and feasibility of impression taking

OBJECTIVES

Clinical data for CAD/CAM post and cores (PC) is still scarce, even though developments in digital dentistry have improved dental treatment in many aspects. Therefore, the purpose of this in vivo study was to compare CAD/CAM PC fabricated in a fully digital chairside workflow to conventional cast PC (CPC) according to the accuracy of fit and the impression taking. The null hypothesis was that there is no significant difference between CAD/CAM PC and CPC.

METHODS

The study was conducted on 30 teeth in 25 patients receiving a CPC during their prosthetic treatment plan. On each tooth a conventional and a digital post impression were taken. Subsequently, one CPC following a conventional and one CAD/CAM PC following a digital workflow were fabricated. Both PC were tried-in intraorally and assessed according to a standardised evaluation sheet. The deviation between the two impression methods was evaluated by superimposing the datasets in a 3D analysis software. Statistical analysis for pairwise comparison was conducted according to Wilcoxon and median test with a significance level of p = 0.05.

RESULTS

CAD/CAM PC performed significantly better compared to CPC according to accuracy of fit (p = 0.022) and feasibility of impression taking (p < 0.001). The deviation between post impression methods increased from "coronal" to "apical". Between "coronal"/"middle" no significant difference (p = 0.158) was detected, whereas the pairwise comparison between the other measurement categories showed significant differences (p = 0.002, p < 0.001).

CONCLUSIONS

The null hypothesis was rejected since CAD/CAM PC performed significantly better and the deviation between the post impression methods showed significant differences.

CLINICAL SIGNIFICANCE

By using intraoral scanners (IOS) teeth can be restored with customised CAD/CAM PC in a single session. Within the limitations of this study the fully digital chairside workflow led to superior accuracy of fit of PC and higher feasibility of impression taking than the conventional workflow for CPC.

Evaluation of Poly(etheretherketone) Post's Mechanical Strength in Comparison with Three Metal-Free Biomaterials: An In Vitro Study

The thinking about metallic replacement has begun in a global context of reducing metallic alloys' use in odontology. Among the materials proposed for their replacement, poly(etheretherketone) may present interesting properties, especially in removable dentures' frames. The purpose of this study is to evaluate fracture resistance of PEEK posts-and-cores compared to non-metallic CAD/CAM materials and fiber glass posts. Forty extracted maxillary central incisors were prepared to receive posts. Samples were divided into four groups depending on whether they had been reconstructed with LuxaCam® PEEK, Enamic®, Numerys GF® or LuxaPost®. Samples were submitted to an oblique compressive test and results were statistically analyzed with ANOVA and Student's tests (or non-parametric tests depending on the conditions). Glass fiber posts and Numerys GF® reveal a significantly higher fracture resistance than LuxaCam® PEEK and Enamic®. No exclusively dental fracture has been noted for the Enamic group, which significantly distinguishes these samples from the three other groups. In our study, it appears that the conception of posts and cores with hybrid ceramic never conducts to a unique tooth fracture. By weighting the results according to the materials used, our data, obtained for the first time on this type of PEEK block, cannot confirm the possibility of using PEEK for inlay-core conception, excepted for specific cases when the material is considered in a patient presenting allergies or systemic disease contraindicating resin or metal.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

The effect of different ferrule heights and crown-to-root ratios on fracture resistance of endodontically-treated mandibular premolars restored with fiber post or cast metal post system: an in vitro study

BACKGROUND

This study aimed to investigate the effects of different ferrule heights and crown-to-root ratios on the fracture resistance of endodontically-treated premolars restored with fiber post or cast metal post system.

METHODS

Eighty extracted human mandibular first premolars with single root canal were treated endodontically and cut from 2.0 mm above the buccal cemento-enamel junction, to create horizontal residual roots. The roots were randomly divided into two groups. The roots in group FP were restored with a fiber post-and-core system, while the roots in group MP were restored with a cast metal post-and-core system. Each group was divided into five subgroups with different ferrule heights (0: no ferrule; 1: 1.0 mm ferrule; 2: 2.0 mm ferrule; 3: 3.0 mm ferrule; 4: 4.0 mm ferrule). All specimens were subsequently restored with metal crowns and embedded in acrylic resin blocks. The crown-to-root ratios of the specimens were controlled at approximately 0.6, 0.8, 0.9, 1.1, and 1.3 of the five subgroups, respectively. Fracture strengths and fracture patterns of the specimens were tested and recorded by a universal mechanical machine.

RESULTS

Mean fracture strengths (mean ± standard deviation (kN)) of FP/0 to FP/4 and MP/0 to MP/4 were: 0.54 ± 0.09, 1.03 ± 0.11, 1.06 ± 0.17, 0.85 ± 0.11; 0.57 ± 0.10, 0.55 ± 0.09, 0.88 ± 0.13, 1.08 ± 0.17, 1.05 ± 0.18 and 0.49 ± 0.09, respectively. Two-way ANOVA revealed significant effects of different ferrule heights and crown-to-root ratios on the fracture resistance (P < 0.001), but no difference in fracture resistance between two post-and-core systems (P = 0.973). The highest fracture strengths of the specimen were found with the ferrule length of 1.92 mm in group FP and 2.07 mm in group MP, the crown-to-root ratio of which in 0.90 and 0.92 respectively., there is a significant difference in fracture patterns among the groups(P < 0.05).

CONCLUSIONS

When a certain height of ferrule is prepared and a cast metal or fiber post-and-core system is restored for the residual root, the clinical crown-to-root ratio of the tooth after restoration should be kept within 0.90 to 0.92, so as to improve the fracture resistance of endodontically-treated mandibular first premolars.

Dental Fiber-Post Systems: An In-Depth Review of Their Evolution, Current Practice and Future Directions

The field of dental medicine is constantly evolving and advancing toward minimally invasive techniques. Several studies have demonstrated that bonding to the tooth structure, particularly enamel, yields the most predictable results. In some instances, however, significant tooth loss, pulpal necrosis, or irreversible pulpitis may limit the options available to the restorative dentist. In these cases, placement of a post and core followed by a crown is the preferred treatment option, provided all requirements are met. This literature review provides an overview of the historical development of dental FRC post systems as well as a comprehensive examination of the currently available posts and their bonding requirements. In addition, it offers valuable insights for dental professionals seeking to understand the current state of the field and the prospects of dental FRC post systems.

Survival rate and treatment success of glass fiber posts cemented with two adhesive cementation strategies after up to 106 months: a randomized clinical trial

OBJECTIVES

The objective of this study is to evaluate the longevity of two fiber post cementation strategies in a prospective, multicenter, non-inferiority, double-blind randomized controlled trial.

METHODS

A total of 152 teeth, with adequate endodontic treatment and loss of coronal structure and bilateral simultaneous posterior occlusal contacts, were randomly allocated to receive glass fiber posts cemented with a conventional cementation strategy (CRC group: adhesive system + resin cement) (Adper Single Bond + RelyX ARC; 3 M-ESPE) or a self-adhesive cementation strategy (SRC group: self-adhesive resin cement; RelyX U100/U200; 3 M-ESPE). The patients were recalled annually for clinical and radiographical evaluation with a 93% recall rate (142 teeth, with 74 at CR groups and 68 at SRC group). The primary outcome was survival rate, considering the fiber post debonding (loss of retention). The secondary outcome included the success rate of the prosthetic treatment with crown debonding, post fracture, and tooth loss (not related to post failure). Both outcomes were evaluated annually. The Kaplan-Meier method and Cox regression with 95% confidence interval were used for the statistical analysis.

RESULTS

For the primary outcome (failures directly related to fiber posts cementation strategy), there were 4 fiber post debondings (2 per group), 8 root fractures (3 for SRC group and 5 for CRC group), and one mixed failure (debonding combined with root fracture for CRC), with both strategies presenting similar survival rates (p = 0.331), with 88.9% for the CRC group and 90.9% for the SRC group. For the secondary outcome (failures not related to fiber post cementation strategies), there were 8 crown debondings, 3 post fractures, and 3 tooth losses, with no statistically difference between groups (p = 0.701), with 77% for SRC and 82% for CRC.

CONCLUSION

Fiber post cementation strategies with conventional or self-adhesive resin cement presents similar tooth survival and success rates.

TRIAL REGISTRATION

NCT01461239 CLINICAL RELEVANCE: Both adhesive cementation strategies led to high survival and success rates and are indicated for fiber post cementation, even after a long follow-up period (up to 106 months).

Longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores with self-adhesive resin cement: an update of a prospective analysis with up to 106 months of follow-up

OBJECTIVES

To evaluate the longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores using a self-adhesive resin cement in a prospective clinical descriptive study.

METHODS

A total of 152 teeth were endodontically treated and received resin composite prosthetic cores and metal-ceramic crowns cemented with a self-adhesive resin cement. The patients included in the sample were recalled for clinical and radiography evaluation in an up-to-106-month period after the final cementation procedures, with an average of 62 months of follow-up. 91.5% of the sample (142 teeth) were evaluated regarding the treatment survival rate, analyzed considering the loss of crown retention (crown debonding) and tooth loss as the primary outcome. In addition, post debonding, and root fracture occurrences were also recorded as secondary outcomes to evaluate the success rate of the prosthetic treatment. The aesthetic parameters were also evaluated according to the FDI criteria. The Kaplan-Meier method and Cox regression with 95% confidence interval were applied for the statistical analysis.

RESULTS

Regarding the primary outcome, the metal-ceramic crowns cemented with self-adhesive resin cement presented a high survival rate (91.5%), with 8 crown debondings and 3 tooth losses (1 due to caries and 2 due to periodontal disease) occurring after the evaluation period. For secondary outcomes, 9 root fractures and 4 post debondings occurred, generating a success rate of 72%. All crowns had a score 1 on the FDI criteria, indicating that they were clinically excellent or very good regarding the aesthetic parameters.

CONCLUSION

The metal-ceramic crowns luted with a self-adhesive resin cement presented a survival rate of 91.5% after an average of 62 months of follow-up. Furthermore, the restorations remained aesthetically satisfactory over time, without changes that would indicate prosthetic retreatment. A success rate of 72% was obtained considering the secondary outcome, mainly related to intraradicular retainer failures (root fractures or post debonding).

CLINICAL SIGNIFICANCE

The self-adhesive resin cement is clinically indicated for cementation of metal-ceramic crowns onto resin composite prosthetic cores.

Present status and future directions: The restoration of root filled teeth

This narrative review will focus on a number of contemporary considerations relating to the restoration of root filled teeth and future directions for research. Clinicians are now more than ever, aware of the interdependence of the endodontic and restorative aspects of managing root filled teeth, and how these aspects of treatment are fundamental to obtaining the best long-term survival. To obtain the optimal outcomes for patients, clinicians carrying out endodontic treatment should have a vested interest in the restorative phase of the treatment process, as well as an appreciation for the structural and biomechanical effects of endodontic-restorative procedures on restoration and tooth longevity. Furthermore, the currently available research, largely lacks appreciation of occlusal factors in the longevity of root filled teeth, despite surrogate outcomes demonstrating the considerable influence this variable has. Controversies regarding the clinical relevance of minimally invasive endodontic and restorative concepts are largely unanswered with respect to clinical data, and it is therefore, all too easy to dismiss these ideas due to the lack of scientific evidence. However, conceptually, minimally invasive endodontic-restorative philosophies appear to be valid, and therefore, in the pursuit of improved clinical outcomes, it is important that the efficacies of these treatment protocols are determined. Alongside an increased awareness of the preservation of tooth structure, developments in adhesive bonding, ceramic materials and the inevitable integration of digital dentistry, there is also a need to evaluate the efficacy of new treatment philosophies and techniques with well-designed prospective clinical studies.

PEEK in Fixed Dental Prostheses: Application and Adhesion Improvement

Polyetheretherketone (PEEK) has been widely applied in fixed dental prostheses, comprising crowns, fixed partial dentures, and post-and-core. PEEK’s excellent mechanical properties facilitate better stress distribution than conventional materials, protecting the abutment teeth. However, the stiffness of PEEK is not sufficient, which can be improved via fiber reinforcement. PEEK is biocompatible. It is nonmutagenic, noncytotoxic, and nonallergenic. However, the chemical stability of PEEK is a double-edged sword. On the one hand, PEEK is nondegradable and intraoral corrosion is minimized. On the other hand, the inert surface makes adhesive bonding difficult. Numerous strategies for improving the adhesive properties of PEEK have been explored, including acid etching, plasma treatment, airborne particle abrasion, laser treatment, and adhesive systems.

Fracture Resistance and Stress Distribution Pattern of Different Posts-Core Systems in Immature Teeth: An In Vitro Study and 3D Finite Element Analysis

Introduction

Restoration of immature teeth with open apices and thin dentinal walls with conventional post systems remains a challenge. The purpose of this study was to evaluate the fracture resistance of simulated immature teeth restored with different intraradicular posts and assess their stress distribution pattern using 3D Finite Element Analysis (FEA).

Methods

Fracture strength testing using universal testing machine was carried out in simulated immature teeth restored with different intraradicular posts grouped as follows: Group A: teeth not restored with posts served as control group; Group B: Cast metal post (CMP); Group C: Customized Composite Post (CCP); Group D: Fiber post (FP). Four 3D FEA models of the above groups were created using CATIA^TM software and analyzed for stress distribution using ANSYS^TM. The results of fracture strength testing and FEA were correlated. Multiple group comparisons were analyzed by one-way ANOVA followed by Tukey HSD post hoc test.

Results

The CMP exhibited highest fracture resistance (336.43 N) but resulted in root fractures. The CCP exhibited lower fracture resistance (240.90 N) and favorable stress distribution as compared to CMP. The FP and control group exhibited lower fracture resistance values of 182.69 N and 130.46 N, respectively. The results of 3D FEA demonstrated higher stress concentration in model comprising metallic post and core.

Conclusions

Teeth restored with cast metal posts and cores exhibited maximum fracture resistance followed by the customized composite posts, the fiber posts, and the control group. The cast metal posts indicated higher von Mises stresses concentrated in the radicular region; however, the customized composite posts, the fiber posts, and the control group demonstrated stress concentration in the coronal region.

Bond strength and failure mode of glass fiber posts with different surface treatments prior to silanization: An in vitro comparative study

Aim

The use of chemical agents in the surface treatment of glass fiber posts can improve their bond strength to the root canal. The aim of this study was to assess the bond strength and failure mode of glass fiber posts that received different surface treatments prior to silanization.

Materials and Methods

In this cross-sectional and in vitro experimental study, 50 human lower premolar roots were randomly divided into five groups and subsequently prepared to receive the cementation of a fiberglass post prior to silanization. They were distributed as group 1 (with 24% hydrogen peroxide), group 2 (with 37% phosphoric acid), group 3 (with 1.23% acidulated phosphate fluoride for 2 minutes), group 4 (with 1.23% acidulated phosphate fluoride for 6 minutes), and group 5 (without pretreatment). After cementation, the roots were sectioned into two discs for each cervical, middle, and apical region. Bond strength was assessed using the push out technique. Adhesive, mixed, and cohesive failure modes were also assessed. For data analysis, ANOVA and Tukey's post hoc tests were used, as well as Pearson's chi-square test. A significance of P < 0.05 was considered in all statistical analyses.

Results

When comparing the bond strength of root regions, significant differences were obtained in groups pretreated with phosphoric acid (P = 0.018) and acidulated phosphate fluoride for 2 and 6 minutes (P = 0.001 and P = 0.000, respectively). Furthermore, significant differences were obtained between posts treated only with silane and those that received phosphoric acid pretreatment (P = 0.006) and acidulated phosphate fluoride for 6 minutes (P = 0.001). Significant association of mixed failure mode was observed with hydrogen peroxide (P = 0.014) and phosphoric acid (P = 0.006) pretreatments. Cohesive failure was significantly associated with acidulated phosphate fluoride pretreatment for 2 minutes (P = 0.032) and with posts that did not receive treatment prior to silanization (P = 0.000).

Conclusion

Posts treated only with silane and pretreated with hydrogen peroxide and acidulated phosphate fluoride for 2 minutes presented significantly higher bond strength with respect to those pretreated with phosphoric acid and acidulated phosphate fluoride for 6 minutes. However, acidulated phosphate fluoride for 2 minutes and silane were associated with a better bonding type.