Mechanical properties and superficial characterization of a milled CAD-CAM glass fiber post

Polyetheretherketone split post and core for restoration of multirooted molar with insufficient dental tissue remnants by digital techniques: a case report and 3-year follow up

BACKGROUND

Multi-rooted teeth with extensive dental defects often face challenges in stability and biomechanical failure. High-performance polymer PEEK materials, with properties closer to dentin, show promise in reducing stress concentration and preserving tooth structure. This report aimed to explore the use of a highly retentive polyetheretherketone (PEEK) for manufacturing custom-made split post and core for the restoration of grossly destroyed endodontically treated molars.

CLINICAL CONSIDERATIONS

A 40-year-old female patient presented with complaints of loss of tooth substance in the posterior mandibular tooth. This case involved the digital design and fabrication of PEEK split post and core to restore multirooted molar with insufficient dental tissue remnants. The restorations were evaluated over a 3-year follow-up using the World Federation criteria (FDI). The restoration was clinically evaluated through intraoral examination, radiographic assessment, and subjective patient satisfaction, and was deemed clinically good according to FDI criteria.

CONCLUSION

The outstanding mechanical properties of PEEK, coupled with the structure of the split post, provide an effective treatment option for weakened multirooted teeth. Simultaneously, the restoration configuration effectively addressed the challenge of varying postinsertion directions, and the interlocking mechanism between the primary and auxiliary posts enhanced the stability of the post and core.

CAD-CAM glass fiber compared with conventional prefabricated glass fiber posts: A systematic review

STATEMENT OF PROBLEM

A prefabricated glass fiber post provides esthetic and biomechanical benefits for severely damaged endodontically treated teeth; however, failures in post retention remain a challenge.

PURPOSE

The purpose of this systematic review was to compare the fracture resistance and bond strength of prefabricated glass fiber posts to those made with computer-aided design and computer-aided manufacturing (CAD-CAM).

MATERIAL AND METHODS

This review was entered into PROSPERO (CRD42020213668) and was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic systematic searches of PubMed/MEDLINE, Embase, and the Cochrane Library were conducted for published articles until October 2020. Studies that compared prefabricated glass fiber posts with CAD-CAM-fabricated glass fiber posts were selected, and studies that had not been published in English or in the previous 10 years were excluded. The fracture resistance (N) and bond strength (MPa) were the primary outcomes.

RESULTS

After reviewing the title, abstract, and the entire text of 227 articles, 8 studies were selected. Four studies were omitted. Four of the 8 studies were retained for qualitative analyses, with 1 having a high risk of bias and 3 having a medium risk of bias. Only 1 study found significantly higher fracture resistance in the CAD-CAM group than in the prefabricated group. The bond strength study reported a significant difference, with the CAD-CAM group having greater bond strength than the prefabricated group.

CONCLUSIONS

Despite the high heterogeneity and the few included articles, a tendency was found for the CAD-CAM-fabricated glass fiber post to improve fracture resistance and bond strength. However, the available literature is insufficient to draw definitive conclusions.

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.

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.

Fracture resistance and failure mode of three esthetic CAD-CAM post and core restorations

BACKGROUND

The rising demand for improved aesthetics has driven the utilization of recently introduced aesthetic materials for creating custom post and core restorations. However, information regarding the fracture resistance of these materials remains unclear, which limits their practical use as custom post and core restorations in clinical applications. AIM OF THE STUDY: This study aimed to evaluate the fracture resistance of three non-metallic esthetic post and core restorations and their modes of failure.

MATERIALS AND METHODS

Thirty-nine single-rooted human maxillary central incisors were endodontically treated. A standardized post space preparation of 9mm length was performed to all teeth to receive custom-made post and core restorations. The prepared teeth were randomly allocated to receive a post and core restoration made of one of the following materials (n=13): glass fiber-reinforced composite (FRC), polyetheretherketone (PEEK) and polymer-infiltrated ceramic-network (PICN). An intraoral scanner was used to scan all teeth including the post spaces. Computer-aided design and computer-aided manufacturing (CAD-CAM) was used to fabricate post and core restorations. Post and core restorations were cemented using self-adhesive resin cement. All specimens were subjected to fracture resistance testing using a universal testing machine. Failure mode analysis was assessed using a stereomicroscope and SEM. The data was statistically analyzed using One-Way ANOVA test followed by multiple pairwise comparisons using Bonferroni adjusted significance level.

RESULTS

Custom PEEK post and core restorations displayed the least fracture load values at 286.16 ± 67.09 N. In contrast, FRC exhibited the highest average fracture load at 452.60 ± 105.90 N, closely followed by PICN at 426.76 ± 77.99 N. In terms of failure modes, 46.2% of specimens with PICN were deemed non-restorable, while for PEEK and FRC, these percentages were 58.8% and 61.5%, respectively.

CONCLUSIONS

Within the limitation of this study, both FRC and PICN demonstrated good performance regarding fracture resistance, surpassing that of PEEK.

Comparative Analysis of the Mechanical Properties and Biocompatibility between CAD/CAM and Conventional Polymers Applied in Prosthetic Dentistry

Modern media often portray CAD/CAM technology as widely utilized in the fabrication of dental prosthetics. This study presents a comparative analysis of the mechanical properties and biocompatibility of CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) polymers and conventional polymers commonly utilized in prosthetic dentistry. With the increasing adoption of CAD/CAM technology in dental laboratories and practices, understanding the differences in material properties is crucial for informed decision-making in prosthodontic treatment planning. Through a narrative review of the literature and empirical data, this study evaluates the mechanical strength, durability, esthetics, and biocompatibility of CAD/CAM polymers in comparison to traditional polymers. Furthermore, it examines the implications of these findings on the clinical outcomes and long-term success of prosthetic restorations. The results provide valuable insights into the advantages and limitations of CAD/CAM polymers, informing clinicians and researchers about their suitability for various dental prosthetic applications. This study underscores the considerable advantages of CAD/CAM polymers over conventional ones in terms of mechanical properties, biocompatibility, and esthetics for prosthetic dentistry. CAD/CAM technology offers improved mechanical strength and durability, potentially enhancing the long-term performance of dental prosthetics, while the biocompatibility of these polymers makes them suitable for a broad patient demographic, reducing the risk of adverse reactions. The practical implications of these findings for dental technicians and dentists are significant, as understanding these material differences enables tailored treatment planning to meet individual patient needs and preferences. Integration of CAD/CAM technology into dental practices can lead to more predictable outcomes and heightened patient satisfaction with prosthetic restorations.

Comparative analysis of stress distribution in residual roots with different canal morphologies: evaluating CAD/CAM glass fiber and other post-core materials

BACKGROUND

The selection of post-core material holds significant importance in endodontically treated teeth, influencing stress distribution in the dental structure after restoration. The use of computer-aided design/computer-aided manufacturing (CAD/CAM) glass fiber post-core possesses a better adaptation for different root canal morphologies, but whether this results in a more favorable stress distribution has not been clearly established.

MATERIALS AND METHODS

This study employed finite element analysis to establish three models of post-core crown restoration with normal, oversized, and dumbbell-shaped root canals. The three models were restored using three different materials: CAD/CAM glass fiber post-core (CGF), prefabricated glass fiber post and resin core (PGF), and cobalt-chromium integrated metal post-core (Co-Cr), followed by zirconia crown restoration. A static load was applied and the maximum equivalent von Mises stress, maximum principal stress, stress distribution plots, and the peak of maximum displacement were calculated for dentin, post-core, crown, and the cement acting as the interface between the post-core and the dentin.

RESULTS

In dentin of three different root canal morphology, it was observed that PGF exhibited the lowest von Mises stresses, while Co-Cr exhibited the highest ones under a static load. CGF showed similar stress distribution to that of Co-Cr, but the stresses were more homogeneous and concentrated apically. In oversized and dumbbell-shaped root canal remnants, the equivalent von Mises stress in the cement layer using CGF was significantly lower than that of PGF.

CONCLUSIONS

In oversized root canals and dumbbell-shaped root canals, CGF has shown good performance for restoration of endodontically treated teeth.

CLINICAL RELEVANCE

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

Biomechanical behavior of weakened roots restored with custom-made post-and-cores of glass fiber and polyetheretherketone

PURPOSE

To evaluate the influence of post type and mechanical aging on compression force resistance, fracture pattern, and stress distribution in weakened roots.

MATERIALS AND METHODS

Bovine roots were endodontically treated and widened-and randomly divided into 8 groups (n = 10) according to post type (prefabricated glass fiber post and customized anatomic glass fiber post, milled glass fiber post-and-core, and milled polyetheretherketone post-and-core) and mechanical aging (without and with mechanical aging). Three hundred thousand cycles of mechanical fatigue were performed and compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α = 0.05). Fracture patterns were reported and stress distribution was analyzed by finite elements analysis.

RESULTS

There was a significant effect of post type (p = 0.032) and mechanical aging (p = 0.009), but no double interaction (p = 0.879). Higher values were recorded in the milled glass fiber and polyetheretherketone post-and-core groups compared to the prefabricated glass fiber post groups, and no significant difference was found among anatomic glass fiber post groups and other groups. Reparable fractures were predominant in the milled glass fiber and polyetheretherketone post-and-core groups. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

CONCLUSIONS

Post type and mechanical aging influence the compression force resistance and fracture pattern of weakened roots. Milled glass fiber and polyetheretherketone post-and-cores exhibited higher compression force resistance and more reparable fractures compared to prefabricated glass fiber posts. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

Recent Advances in 3D Printing of Polymers for Application in Prosthodontics

Contemporary mass media frequently depict 3D printing as a technology with widespread utilization in the creation of dental prosthetics. This paper endeavors to provide an evidence-based assessment of the current scope of 3D printing's integration within dental laboratories and practices. Its primary objective is to offer a systematic evaluation of the existing applications of 3D-printing technology within the realm of dental prosthetic restorations. Furthermore, this article delves into potential prospects, while also critically examining the sustained relevance of conventional dental laboratory services and manufacturing procedures. The central focus of this article is to expound upon the extent to which 3D printing is presently harnessed for crafting dental prosthetic appliances. By presenting verifiable data and factual insights, this article aspires to elucidate the actual implementation of 3D printing in prosthetic dentistry and its seamless integration into dental practices. The aim of this narrative review is twofold: firstly, to provide an informed and unbiased evaluation of the role that 3D printing currently plays within dental laboratories and practices; and secondly, to instigate contemplation on the transformative potential of this technology, both in terms of its contemporary impact and its future implications, while maintaining a balanced consideration of traditional dental approaches.

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.

Evaluation of Bond Strength and Fracture Load of Teeth With Flared Root Canals Restored With Prefabricated, Anatomical, and Computer-aided Design and Computer-aided Manufacturing Fiber Posts

PURPOSE

This study compared the use of anatomical glass fiber posts using bulk-fill composite resin with computer-aided design and computer-aided manufacturing (CAD/CAM) milled glass fiber post in oversized root canals, through bond strength (BS) and fracture resistance (FR) tests (fracture load).

METHODS AND MATERIALS

A total of 48 mandibular premolars were selected, half of them had their crowns removed at the cemento-enamel junction (CEJ) and the other half were sectioned 2 mm above the CEJ. Subsequently, teeth were endodontically treated. After 1 week, the standard preparation of the canals was carried out, and the roots were divided into three groups (n=16), according to the use of different restorative techniques (control: prefabricated glass fiber post [PFP], direct anatomical glass fiber post [AFP], and CAD/CAM milled glass fiber post [MFP]). After luting procedures using Single Bond Universal and RelyX Ultimate (3M ESPE), for eight teeth in each group, six specimens were obtained (two slices from each root third: cervical, middle, and apical). For the remaining eight roots of each group, standardized preparations for metal-free crowns, milling of 5 mol% yttria-stabilized tetragonal zirconia polycrystalline, cementation of the crowns, and periodontal ligament simulation were performed. Then, for each group, the BS was evaluated through the push-out test, and the FR was evaluated in compression. The data obtained from BS were submitted to two-way analysis of variance (ANOVA; group vs root region) and Tukey (α=0.05) and from FR to one-way ANOVA (group) and Tukey (α=0.05).

RESULTS

For the BS test, the MFP group was statistically superior to the PFP group in all root regions and was statistically superior to the AFP group only in the cervical region, being statistically similar in the middle and apical root regions. For the FR test, the MFP group was statistically superior to the PFP and AFP groups.

CONCLUSION

The milled fiber post technique can be a legitimate alternative in the restoration of weakened roots with flared root canals.

A digital technique for a prefabricated custom post-and-core restoration

This technique provides a prefabricated and custom post-and-core to restore endodontically treated teeth to be delivered at the preparation appointment. Cone beam computed tomography (CBCT) is used to extract the post shape from a root canal, and a computer-aided design and computer-aided manufacturing (CAD-CAM) software program is used to design the core. The post and the core are combined and milled before post space preparation. Three-dimensional preparation guides are fabricated and used in post space preparation to ensure that the prefabricated and custom post-and-core fits after the preparation. This technique can save time and reduce the risk of perforation while preparing the root canal.

Fibre-reinforced Cad/CAM post and cores: The new "gold standard" for anterior teeth with extensive coronal destruction?-A fully digital chairside workflow

Objectives

Since one-third of persons suffer a dental trauma, treatment of anterior teeth using post and core (PC) is becoming important. In teeth with extensive destruction, cast PC (CPC) remain the "gold standard", even though they lead to aesthetic impairment and have a mismatching elastic modulus to that of dentin. Prefabricated fibre-reinforced posts have elastic modulus similar to that of dentin but the accuracy of fit and mechanical stability are worse. This study was aimed to evaluate the deviation and mechanical performance of fibre-reinforced CAD/CAM PC (FRPC) fabricated in a fully digital chairside workflow, compared to those of CPC.

Methods

On 30 teeth, a PC preparation was conducted, and a conventional and digital post impression were taken with an intraoral scanner. Fifteen teeth each were treated with CPC and FRPC, respectively. The deviation was evaluated by superimposing the datasets of the digitalised stone models and digital post impressions. Decementation and root fracture during chewing simulation were analysed by microscopy and X-ray. Statistical analysis was performed by pairwise comparison and Kaplan-Meier analysis.

Results

The median deviation for the "coronal", "middle" and "apical" were 14.5, 18.0 and 113.7 μm, respectively. The pairwise comparison for "coronal"/"middle" showed no significance (p = 0.465), whereas that for "coronal"/"apical" and "middle"/"apical" showed highly significant differences (p < 0.001). After chewing simulation, five decementations and two root fractures were detected for CPC. For FRPC, neither decementation nor root fracture were documented.

Significance

Within the limitations of this study, FRPC performed significantly better than CPC.

Application of polyetheretherketone (PEEK) posts: evaluation of fracture resistance and stress distribution in the root: in vitro and finite element analyses

To evaluate the feasibility of using a milled polyetheretherketone (PEEK) post and core in endodontically treated teeth with or without a ferrule. Sixty bovine tooth roots were endodontically treated followed by cementation of intraradicular retainers (IR), according to each experimental group: a) non-ferrule glass fiber post (f0FP); b) 2-mm-ferrule glass fiber post (f2FP); c) non-ferrule resized glass fiber post (f0PR); d) 2-mm-ferrule resized glass fiber post (f2PR); e) non-ferrule PEEK post and core (f0PPC); and f) 2-mm-ferrule PEEK post and core (f2PPC). Metal crowns were made and cemented. A periodontal ligament was simulated using polyether. A force was applied to the palatine portion of each sample at 45°, until fracture. Fracture resistance data were submitted to two-way ANOVA and Tukey's test (α = 0.05). Three-dimensional digital models were developed to calculate the tensions formed in the root using finite element analysis. Models of glass fiber posts and PEEK posts and cores were evaluated with or without a ferrule. The results were analyzed by the Mohr-Coulomb criterion. The type of IR was not influenced by fracture strength (p = 0.243). There were significant statistical differences among the remaining factors. Ferrule groups had greater fracture resistance, and the failure mode of teeth with a ferrule was more catastrophic than the non-ferrule group. A ferrule increases fracture resistance and influences failure mode; the PEEK post and core did not modify the biomechanics of endodontically treated teeth, and resembled the glass fiber post results. The crack initiation point differed between the ferrule and non-ferrule groups.

Effect of endodontic sealers on push-out bond strength of CAD-CAM or prefabricated fiber glass posts

This study aimed to evaluate the effect of endodontic sealer (ES) on bond strength (BS) of prefabricated or milled-CAD-CAM (computer-aided design and computer-aided manufacturing) glass-fiber-posts (GFP). Canals of 90 single-rooted teeth were prepared for filling by the single-cone technique with gutta-percha and one of the following ES: AH Plus (epoxy resin), Endofill (zinc-oxide and eugenol), and Bio-C Sealer (calcium-silicate). After post-space preparation, tooth-specimens were equally divided in half according to type of GFP to be used. In the half to receive milled-CAD-CAM posts, tooth specimens were molded with acrylic resin to obtain replicas. These were scanned to enable the laboratory to produce the milled-CAD-CAM GFPs (Fiber CAD Lab, Angelus) by the subtractive technique. The other half of samples received prefabricated GFPs (Exacto, Angelus) (n=15). The GFPs were cemented with dual-cure resin cement (Panavia F2.0, Kuraray). Each root was sectioned into two slices per root region (cervical, middle, apical) that were subjected to the push-out BS test, in a universal testing machine. Failure mode (FM) was classified by scores. The BS data were submitted to generalized linear model analyses, while FM was analyzed using the chi-square test (a=0.05). BS showed no significant difference among the three ES (p > 0.05). BS was significantly higher for prefabricated (mean 10.84 MPa) versus milled-CAD-CAM GFPs (mean 6.94 MPa) (p <0.0001), irrespective of ES. The majority showed mixed failures. It could be concluded that type of ES did not affect BS of GFPs to dentin, and prefabricated-GFPs had higher bond-strength than customized-milled-CAD-CAM GFPs.

Evaluation of a half-digital technique for fabricating customized post-cores: A pilot study

Objectives

The current half-digital post-core fabrication technique can replace the conventional methods; however, it does not consider the impact occlusion has on the digital design. This study proposed a half-digital workflow that integrated intracanal impression with dentition scanning, and evaluated the accuracy of the post-cores fabricated by it.

Methods

Standard models with three extracted teeth (a central incisor, a premolar, and a molar) were prepared. Eight post-cores were fabricated for each tooth by the half-digital technique and eight by the conventional technique as controls. Scanning was performed with a microcomputed tomography system. The volume of the overall space (VOS) between the post and canal wall, the space areas in three standardized sections (A, B, and C), and the apical gap (AG) were calculated and statistically analyzed using two-way analysis of variance. Statistical significance was set at p < 0.05.

Results

The two techniques differed significantly in the VOS (p < 0.05), section B (p < 0.05), and AG (p < 0.05) of all three teeth but not for sections A (p = 0.099) and C (p = 0.636).

Conclusions

The half-digital technique investigated in this study could produce better-fitting customized post-cores than the conventional technique.

Fracture resistance of weakened roots restored with relined or milled CAD-CAM glass fiber posts

This in vitro study compared the fracture resistance of weakened roots restored with milled or relined glass fiber post (GFP). Seventy bovine incisors were divided into seven groups, according to the weakening protocol (none: control; medium-weakened: MW; highly-weakened: HW) and post anatomization technique (non-relined, relined with Bulk Fill or Z350 resin; milled GFP: M). Roots were thermomechanical cycled and submitted to compression. Frequencies and groups were compared by the chi-square test and two-factor ANOVA, Tukey's, and t-test (α=5%). The HW-M obtained the lowest values, showing significant differences compared to all groups (p<0.001). The highest value was HW-Bulk fill, with significant difference compared to MW-M (p=0.037) and HW-M (p<0.001). The frequency of repairable fractures was 100% in the control, 87%, and 63% in the MW and HW, respectively. Relined or milled GFPs can be considered to rehabilitate weakened teeth since failure patterns were predominantly repairable in all groups.

The Use of Polyetheretherketone (PEEK) as an Alternative Post and Core Material: Five-Year Follow-Up Report

This clinical report demonstrated the use of polyetheretherketone (PEEK) for manufacturing of custom-made post and core in weakened endodontically treated central incisors. The PEEK structure was manufactured using computer-aided design/computer-aided manufacturing (CAD/CAM). The optimal fit of this custom-made endodontic post allowed a thinner cement layer; and removed the need to manufacture a core build-up. While supplementary clinical trials and in vitro studies are needed to totally elucidate the advantages and limitations of PEEK as an option for post and core manufacturing, this case report showed that it can be promising for a predictable and simplified treatment with five years of success.

Influence of New Sleeve Composite on Fracture Behavior of Anterior Teeth with Flared Root Canals

We evaluated the fracture strength and failure mode of non-ferrule teeth with flared root canals that were restored using new experimental sleeve composites. Fifty endodontically treated anterior teeth with flared root canals were restored with direct restorations utilizing different techniques. Group A had teeth (non-ferrule) restored using commercialized MI glass fiber post + Gradia Core as core build-up. Group B had teeth (non-ferrule) restored with commercialized i-TFC glass fiber post + sleeve system. In Group C, the teeth (non-ferrule) were restored with an experimental sleeve composite with commercialized MI glass fiber post and Gradia Core. Group D, teeth (non-ferrule), were restored using custom-made tapered E-glass filling post and Gradia Core. Group E, teeth (with ferrule), were restored with commercialized MI glass fiber post + Gradia Core. After core construction, all specimens underwent direct composite crown restoration and were loaded until fracture using a universal testing machine. Average fracture loads were compared, and the failure modes were observed. Group C exhibited significantly greater fracture strength than other groups (p < 0.05). Favorable fracture teeth ratio of group C was more than that of the other groups. Thus, the new experimental sleeve composite could be clinically useful for core construction of non-ferrule teeth.

PEEK and fiberglass intra-radicular posts: influence of resin cement and mechanical cycling on push-out bond strength

OBJECTIVES

To evaluate the bond strength of four types of posts (pre-fabricated fiberglass post, fiberglass post anatomized with composite resin, milled fiberglass post, and milled polyetheretherketone (PEEK) post), and two types of resin cements (conventional and self-adhesive) by assessing immediate bond strength and post-mechanical aging at each root third.

MATERIALS AND METHODS

Bovine endodontically treated roots (16 groups, n = 8) were prepared and the posts were produced and luted; the specimens of aging groups were cycled (300,000 cycles under 50 N load at 1.2 Hz frequency); six slices of each root were obtained; push-out test was performed by using a universal testing machine (500 N load at 1 mm/min cross speed); fracture pattern was classified into five levels. The statistical analyses used were three-way ANOVA, Tukey's test (for bond strength), and Fisher's test (for fracture pattern) (α < 0.05).

RESULTS

Differences were found between the cements for posts (conventional: p < 0.001; self-adhesive: p = 0.002), whereas no difference was found for root region (p = 0.941; p = 0.056, respectively); analysis of each root showed significant differences for cements (p < 0.001), posts (p < 0.001), and mechanical cycling (p = 0.001); in terms of double interaction, differences were found for posts and mechanical cycling (p = 0.005); no other interactions were observed (double or triple); the fracture pattern showed difference between the groups for both cements.

CONCLUSIONS

Milled PEEK posts seem to be a good clinical option, but they require improvement of CAD-CAM technology and advances towards their adhesion.

CLINICAL RELEVANCE

Milled posts are promising and can reduce clinical time for rehabilitation of extensively destroyed teeth.

Compressive strength of premolars restored with ceramic crowns and supported with a glass fiber post using different luting agents

Objective

The retention of glass fiber post (GFP) is considered a key factor for the long-term success of restorations of endodontically treated teeth. This study aimed to compare the compressive strength of a ceramic crown supported by a GFP using different luting agents.

Methods

Forty single-rooted premolars were randomly divided into four groups (n = 10 each): control group (teeth without a GFP), Ketac Cem group (glass ionomer), RelyX ARC group (conventional dual-curing resin), and RelyX U200 group (self-adhesive dual-curing resin). After luting of the posts and placement of all-ceramic crowns made using feldspathic porcelain (Noritake EX-3), they were exposed to thermocycling for 1000 cycles and compressive strength tests. Statistical analysis included Kruskal–Wallis test with Dunn’s multi-comparison test.

Results

The Ketac Cem group and RelyX U200 group showed significantly greater fracture resistance to compressive loading than the control group.

Conclusion

This study indicates a possible role of the luting agent used with the GFP in influencing the compressive strength of the restored teeth. In this study, the self-adhesive dual-curing resin and glass ionomer both offered resistance to fractures.

New generation CAD-CAM materials for implant-supported definitive frameworks fabricated by using subtractive technologies

Innovations in digital manufacturing enabled the fabrication of implant-supported fixed dental prostheses (ISFDPs) in a wide variety of recently introduced materials. Computer-aided design and computer-aided manufacturing (CAD-CAM) milling allows the fabrication of ISFDPs with high accuracy by reducing the fabrication steps of large-span frameworks. The longevity of ISFDPs depends on the overall mechanical properties of the framework material including its fit, and the physical properties of the veneering material and its bond with the framework. This comprehensive review summarizes the recent information on millable CAD-CAM framework materials such as pre-sintered soft alloys, fiber-reinforced composite resins, PEEK, and PEKK in high-performance polymer family, and 4Y-TZP. Even though promising results have been obtained with the use of new generation millable CAD-CAM materials for ISFDPs, clinical studies are lacking and future research should focus on the overall performance of these millable materials in both static and dynamic conditions.

Patterns of Post-Endodontic Restoration: A Nationwide Survey of Dentists in Turkey

Developments in materials and techniques, geographical locations, age, specialty, and affiliations of dental practitioners affect the preference of post-endodontic restoration. Thus, this survey aimed to evaluate the trends of dentists in Turkey in terms of post-endodontic restorations. An anonymous survey containing 10 questions regarding demographics, post-endodontic restoration patterns, and factors affecting restoration selection was electronically delivered to the dentists registered in the database of the Turkish Dental Association. The data were analyzed using by a chi-square test and ordinal logistic regression analysis. A total of 1093 surveys from 20,564 participants were collected with a response rate of 5.3%. Half of the participants (52%) preferred composite resins for post-endodontic restorations. Usage of posts was less prevalent amongst prosthodontists and dentists with clinical experience of more than 20 years compared to endodontists (p < 0.001) and dentists with clinical experience of less than 5 years (p = 0.004). More than half of the participants (56%) utilized fiber posts. Composite resins and fiber posts were the most common preferences in post-endodontic restoration. Endodontists had a higher tendency to use posts than prosthodontists and general dental practitioners.

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

Objective

The aim of this systematic review was to provide an overview of available scientific evidence regarding the comparative efficacy of computer-aided design (CAD) and computer-aided manufacturing (CAM) glass fiber posts with prefabricated and metal cast posts for the restoration of endodontically treated teeth (ETT).

Methods

This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic and manual searches were performed using the PubMed, SciELO, Cochrane, ScienceDirect, Web of Science, and EBSCO databases. The reference lists of the selected papers were reviewed to identify relevant papers. There were no year restrictions, and eligible studies were those in English publications and describing in vitro studies evaluating intraradicular retainers (IRs) for (i) fracture resistance, (ii) bond strength, (iii) adaptation, and (iv) cement layer thickness. Literature reviews, systematic reviews, meta-analyses, case reports, in vitro studies with <8 specimens, and noncomparative trials involving prefabricated or metal cast posts were excluded. The authors of this review independently screened the search results, extracted data, and assessed the risk of bias.

Results

No significant differences were found in fracture resistance between prefabricated and CAD/CAM glass fiber posts or between CAD/CAM glass fiber and metal cast posts, although the latter demonstrated higher fracture resistance than the prefabricated glass fiber posts. Restoration with a full crown was not necessary to increase the fracture resistance in the presence of the ferrule effect. CAD/CAM glass fiber and metal cast posts had higher bond strength, lower nanoleakage, and better adaptation to the root canal.

Conclusions

Despite the heterogeneity of methodologies and results reported, the results of these studies indicated that the CAD/CAM glass fiber and metal cast posts showed greater efficacy in terms of fracture resistance, retention, and adaptation, compared to prefabricated glass fiber posts.

Effect of Yb: Fiber laser on surface roughness and wettability of titanium

Background/Aim: In recent years, the role of computer aided design (CAD) and computer aided manufacturing (CAM) in dentistry has increasingly become important. However, the influence of different Yb: fiber laser applications on surface roughness of CAD/CAM implant has rarely been studied. The aim of this study is to investigate the effect of different Yb: fiber laser parameters on the surface roughness of CAD/CAM titanium. Material and Methods: Titanium samples, produced by CAD/CAM, were divided into 11 groups according to laser parameters such as scanning types (ST), application angles (AA) and hatch interval (HI). The surface roughness of CAD/CAM titanium was examined for each group. Wettability contact angles (CA) were also determined. Results: The highest surface roughness (43 mm) value was obtained for Group 10 (three-ways ST, 60o AA, 0.07mm HI). The lowest value (2.77 mm) after control group was obtained for Group 6. Surface roughness values, for Group 3, Group 9 and Group 10 were significantly higher than for the other groups (P= 0.000). In contact angle evaluations, the highest contact angle (144o) was observed in Group 10, while the lowest (95o) was observed in control group. Conclusions: Surface roughness was dependent on mixed effect of the laser application parameters. Three-ways ST, 60o AA, 0.07mm HI provided highest surface roughness and wettability contact angles. The surface roughness values of one-way ST, 0.06 mm HI, two-ways HT, 45o AA and 0.08 mm HI and three-ways ST, 60o AA and 0.07 mm HI were significantly higher than for the other groups (P=0.000).

Evaluation of the Behavior of Two CAD/CAM Fiber-Reinforced Composite Dental Materials by Immersion Tests

Fiber-reinforced composites are used as restorative materials for prosthetic oral rehabilitation. Gastroesophageal reflux disease (GERD) is an accustomed affection with various oral manifestations. This study aimed to evaluate the behavior of two high-performance CAD/CAM milled reinforced composites (Trinia™, TriLor) in artificial saliva at different pH levels through immersion tests, and to determine if changes in mass or surface morphology at variable pH, specific for patients affected by GERD, appear. After investigating the elemental composition and surface morphology, the specimens were immersed in Carter Brugirard artificial saliva for 21 days at different pH values (5.7, 7.6, and varying the pH from 5.7 to 3). The values of the weighed masses during the immersion tests were statistically processed in terms of mean and standard deviation. Results suggested that irrespective of the medium pH, the two composites presented a similar mass variation in the range of −0.18 (±0.01)–1.82 (±0.02) mg after immersion, suggesting their stability when in contact with artificial saliva, an aspect which was also highlighted by scanning electron microscope (SEM) analysis performed on the immersed surfaces. Novel composite biomaterials can be a proper alternative for metal alloys used for prosthetic frameworks in patients suffering from GERD.

Development of fibre-reinforced composite disk for computer-aided design-computer-aided manufacturing milled posts; Experimental composite disk using e-glass fibre in different fibre direction

Aims

To evaluate the flexural properties of computer-aided design-computer-aided manufacturing (CAD-CAM) milled posts fabricated from the experimental fibre-reinforced composite disks in different fibre direction, and to compare the flexural properties of the CAD-CAM milled posts to those of commercial prefabricated posts, RelyX and FRC PostecPlus.

Settings and Design

In vitro comparative study.

Materials and Methods

E-glass fibre was used to fabricate the CAD-CAM composite disks. The fibres were prepared in unidirectional and multidirectional arrangements into the epoxy resin, at 70% by weight. The disk was milled by the Cerec InLab CAD-CAM system to fabricate a post. Ten posts for each type of disk were prepared. Two types of commercial fibre posts, RelyX fibre post, and FRC PostecPlus were used as control. The three-point bending test was performed.

Statistical Analysis Used

The data were analysed using one-way ANOVA and Game-Howell post-hoc test.

Results

The results indicated that both commercial fibre posts had the highest flexural strength and flexural modulus. The unidirectional experimental post yielded significantly lower values in both flexural strengths (739.1 ± 24.1 MPa) and flexural modulus (21.0 ± 3.5 GPa) compared to the control posts, while the multidirectional experimental posts had extremely low flexural strength and flexural modulus.

Conclusions

The direction of the fibres significantly influenced the mechanical properties of the posts. The experimental unidirectional fibre-reinforced composite disk showed the potential to be used as a CAD-CAM disk for post and core fabrication.

Stress distribution of a novel bundle fiber post with curved roots and oval canals

OBJECTIVE

The aim of this study was to compare the stress distribution of teeth with curved and straight roots with oval and round canals restored with the bundle and conventional post systems.

MATERIAL AND METHODS

Six three-dimensional premolars were modeled with round and oval canals, and curved roots using the software. The bundle post and the round posts were modeled. All post models were placed on the canals. The models were subjected to 200 N oblique loading. The results were evaluated by von Mises stresses.

RESULTS

This study demonstrated that the bundle post showed higher stress values compared to the conventional post. The stresses in the oval canal were higher than those in the round canal. The highest stress values were found in the curved roots. The stress distribution on the curved roots was observed in the middle and apical third of the canal.

CONCLUSION

The bundle post presented higher stress compared to conventional posts. Besides, a more uniform stress distribution was observed in the bundle groups.

CLINICAL SIGNIFICANCE

When a post was required in extremely irregular, wide canals and curved roots, the bundle post was the material of choice. Canal and root morphology influenced stress distribution.

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.

Shear bond strength of veneering composite to high performance polymers

High performance polymers like PEEK (polyetheretherketone) and FRC (fiberreinforced composite) could substitute metallic alloys for removable partial dentures. However, these polymers require aesthetic veneering. This study was to determine the bond strength to direct composite. Specimens made of PEEK and FRC were produced and air-abraded (50 μm aluminum-oxide). Specimens were allocated to four experimental groups: Luxatemp Glaze & Bond, Scotchbond Universal, SR Nexco Connect and iBond Universal. Specimens were divided into three subgroups for short-term, long-term and no artificial aging and shear bond strength (SBS) was evaluated. SBS of specimens made of PEEK with no artificial aging showed values between 10.79-14.00 MPa, short-term artificial aging resulted in values between 3.78-13.85 MPa and after long-term artificial aging SBS decreased to 0-8.75 MPa. SBS measurement of FRC specimens resulted in values between 9.83-12.1 MPa without aging, after short-term artificial aging values decreased to 8.36-11.98 MPa and after long-term aging SBS showed a degradation to 4.52-7.82 MPa.

Restorative preferences and choices of dentists and students for restoring endodontically treated teeth: A systematic review of survey studies

STATEMENT OF PROBLEM

The best protocol to restore endodontically treated teeth is still unclear, with many factors to be considered, including the selection and necessity of a post, the type of coronal restoration, the amount of remaining coronal structure, and the type of luting agent.

PURPOSE

The purpose of this systematic review was to assess the restorative preferences for endodontically treated teeth between dentists and dental students.

MATERIAL AND METHODS

Survey studies, written in English, of dentists and dental students, which evaluated the use of intracanal posts and other restorative options for endodontically treated teeth, were selected. Searches were performed in the PubMed and SCOPUS databases without time restriction. Screening and data extraction were performed by 2 researchers independently. A standardized outline was used to extract the data (questions related to the theme and the response rate of each question on the survey), and the risk of bias was assessed. Descriptive analysis was performed of the collected information.

RESULTS

Twenty-five articles were included. Most dentists who answered the surveys reported the time since graduation as 1 to 20 years (40%), and 44% were specialists. The most reported choices concerning the type of posts used were prefabricated posts (45.8%), cast metal posts (16.7%), and both posts (16.7%). The cast metal posts were cited more frequently in surveys published between 1994 and 2010, whereas prefabricated posts, both metal and glass fiber ones, were cited between 2006 and 2019. The preferred luting agent for intracanal posts was resin-based (47%). These choices seem to have been influenced by time and by the level of postgraduate training.

CONCLUSIONS

Restorative preferences related to posts have changed over time, from the use of cast posts to prefabricated ones or the use of both posts and seem to be influenced by experience and postgraduate training.

Retentive Characteristics of a Polyetheretherketone Post-Core Restoration with Polyvinylsiloxane Attachments

A new application of a polyetheretherketone (PEEK) post-core restoration combined with polyvinylsiloxane (PVS) attachments was proposed and substantiated. This study aimed to evaluate retentive characteristics of the PEEK post-core restoration with PVS attachment systems. Specimens with PVS attachments were fabricated to evaluate retention force during 10,000 cyclic dislodgements. Additionally, the retention forces of PVS attachments with three different values of Shore hardness were further measured before and after aging treatments. The results of cyclic dislodgement test indicated a strong negative linear relationship between the cyclic times and retention force (p < 0.0001, r = −0.957). Furthermore, the retention forces of the PVS were significantly improved with Shore hardness increased, which was also affected by the aging treatment (F (2, 138) = 10.95, p < 0.0001). Therefore, the PEEK post-core restoration with PVS attachments exhibited the favorable retention force, which could be a promising alternative for dental prostheses.

CAD/CAM Customized Glass Fiber Post and Core With Digital Intraoral Impression: A Case Report

Background

After endodontic treatment, a proper restorative technique is necessary to ensure coronal seal and protection of residual dental structure; teeth which have lost two or more walls need to be restored with posts to increase retention and stability of final restoration. Posts can be distinguished in prefabricated and customized, which are manufactured by lost wax technique or CAD-CAM.

Purpose

Digital dentistry has been developed to increase workflow precision and to accelerate production process; use of CAD-CAM to realize customized posts was limited to scanning plaster models obtained from traditional impressions.

Patients and Methods

In the reported case an intraoral scan was used to mill a post and core restoration on an endodontically treated inferior premolar; this operative protocol was based on previous in vitro experiments that confirmed the ability of 3shape Trios scanner to read post-space up to 9 mm in depth.

Results

The digital technique allows us to convert the concave surface of the root canal into the convex surface of the post, and realize an anatomical post and core that improves the biomechanics of the endodontically treated tooth reducing the possibility of root fractures.

Conclusion

The use of an intraoral digital scanner represents an opportunity for the clinician as it speeds up the production of an anatomical post and core restorations.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/W9qD2b7Eg4o

Surface characterization and bonding properties of milled polyetheretherketone dental posts

PEEK has been used in many dental applications except intra-radicular post. The aim of this study is to test polyetheretherketone (PEEK) as a dental post material through tensile bond strength (TBS) and surface roughness (SR), and to compare it with glass-fiber and cast-metal posts. Thus, 60 human maxillary central incisors with a single root were endodontically treated and divided into three groups (n = 20) according to the type of post (Group P: PEEK, Group F: Glass-fiber, Group M: Cast-metal). Appropriate surface treatment was employed for each group and SR was determined by a three-dimensional non-contact profilometer before cementation. All posts were luted to the canal dentin using self-etch resin cement (Panavia F2.0). Pull-out test was performed on a universal testing machine at a speed of 0.5 mm/min crosshead speed until failure, and TBS were calculated. One-way ANOVA, Tukey's HSD, and Pearson chi-squared tests were performed for statistical analyses (α = 0.05). According to the results, group F demonstrated the highest SR (2.93 ± 0.18 µm) and lowest TBS values (10.05 ± 0.53 MPa), while group P exhibited lowest SR (1.37 ± 0.11 µm) and highest TBS values (14.33 ± 0.58 MPa) (p < 0.001). No significant differences in failure modes were identified among groups, mostly adhesive (p = 0.243). As conclusion, PEEK may be a reliable and contemporary option for dental post systems when used with appropriate surface treatment and luting agent. This high-performance polymer may be a novel candidate as a contemporary dental post system due to its superior mechanical, chemical, thermal, and esthetical properties with low risk of fracture.