An alternative method for fabricating a custom-made metal post with a ceramic core

Scientific mapping of hotspots and trends of post and core research based on the Web of Science: A bibliometric analysis

Statement of problem

Post and core (PC) restoration has been widely used to restore endodontically treated teeth. Nevertheless, bibliometric studies focusing on PC research are lacking.

Purpose

The purpose of this bibliometric analysis was to review the general situation and determine the research direction of PC restoration by means of visualization, including the time development, countries, institutions, authors, journals, research categories, and the information of references with the strongest citation burst.

Material and methods

The search was carried out within the topic field of the Web of Science (WoS) database. CiteSpace, VOSviewer, and R language were used to analyze the literature. Bibliometric indicators in terms of title, keyword, reference, publication time, institution, country and citation information were analyzed.

Results

Between 1966 and 2022, dental research on PC trended upward, especially in 2011 and up to 2022. Scholars in Brazil, the United States, and Italy actively participated in PC research. The country that published the most was Brazil. Italy both ranked first in the H-index and average citations per item and had cooperative relations with several countries. The United States ranked first in the world in total citation count. The University of Siena published the most articles. The Journal of Prosthetic Dentistry (JPD) was the major contributing journal. The top three authors in this field were Ferrari M, Goracci C and Naumann M. The largest cooperative network of authors consisted of four Italian scholars. There were six main clusters of research topics on PC through CiteSpace co-citations. In addition, CiteSpace co-citations, CiteSpace Burst detection and VOSviewer keyword analysis showed the most important research interests, such as bond strength, fiber post, fracture resistance, and finite element analysis. Photodynamic therapy is the latest research hotspot. Finally, there were the top 25 references with the strongest citation bursts, which mainly focused on four aspects, namely, studies related to fiber posts, PC bonding strength, finite element analysis, and residual teeth and the ferrule effect.

Conclusions

This bibliometric analysis provides a comprehensive overview of PC research, including the research time, country, institution, author, journal, article clustering, article keywords, and important literature analysis, so that researchers can have a clear understanding of the research situation in this field.

Evaluation of Retention and Fracture Strength of All Ceramic Crowns with Three Different Esthetic Cast Post-Core Systems

Purpose

This study investigates the fracture and retention strength of all-ceramic crowns with modified composite resin and ceramic cores compared to conventional casted post and core systems.

Materials and Methods

A prepared human central tooth was initially scanned to design and 3D print the post and core. Subsequently, 40 bovine teeth were adjusted to accommodate the fabricated post and cores. They were then divided into four groups of 10 each: group 1 comprised cast cores without cover (control group), group 2 involved cast cores reduced and replaced with IPS Empress material (IPS group), group 3 consisted of cast cores covered with opaque composite (composite group), and group 4 included cast cores covered with opaque ceramic (ceramic group). Zirconia crowns were cemented onto all samples. After an aging process, pull-off and fracture strength tests were conducted. Fracture strength was determined by applying a compressive force at an angle of 135° to the tooth's longitudinal axis until the fracture occurred. For retention strength assessment, a universal testing machine with a 10 mm/min crosshead speed was employed. The resulting data underwent statistical analysis utilizing two-way analysis of variance (ANOVA) and Mann-Whitney U tests.

Results

The analysis revealed no significant difference in fracture strength among the groups (P-value = 0.997). However, the retention strength of the control and IPS groups was significantly higher than that of the other groups.

Conclusion

There were no discernible distinctions among the three study methods regarding fracture strength. Nonetheless, the retention strength of the IPS group resembled that of the control group, surpassing that of the composite and ceramic groups.

Effect of half-digital workflows on the adaptation of custom CAD-CAM composite post-and-cores

STATEMENT OF PROBLEM

Even without the use of an intraoral scanner, post-and-cores can be obtained by using a part-digital fabrication workflow that requires pattern modeling (direct, indirect, or impression); however, studies on the adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin post-and-cores in comparison with metal cast post-and-cores are sparse.

PURPOSE

The purpose of this in vitro study was to analyze the adaptation of CAD-CAM composite resin post-and-cores fabricated through a part-digital fabrication workflow and to compare it with that of metal cast post-and-cores fabricated through conventional methods.

METHOD AND MATERIALS

Eight extracted human premolars were endodontically treated and prepared for custom post-and-cores. Metal cast post-and-cores were fabricated with Ni-Cr alloy (Fit Cast-Sb Plus; Talmax) and conventional resin pattern modeling methods directly in the root canal (conventional direct modeling) or indirectly in a stone cast (conventional indirect modeling). Composite resin post-and-cores were milled from nanohybrid glass-ceramic composite resin CAD-CAM blocks (Brava Block; FGM) by using the part-digital workflow. A laboratory scanner was used to digitalize polyvinyl siloxane impressions (part-digital scanned impression direct CAD-CAM [PSC]) of the root canals and resin patterns fabricated directly (part-digital direct CAD-CAM [PDC]) or indirectly (part-digital indirect CAD-CAM [PIC]). All post-and-cores were placed in the respectively prepared root canals, scanned with microcomputed tomography, and measured in terms of volume of the cementation space, the luting cement film thickness in each root third, and the apical gap between the apical end of the post-and-cores and remaining gutta percha (apical gap). The groups were compared for each adaptation parameter by using 2-way (volume of the cementation space and apical gap) and 3-way (film thickness) ANOVA, and the Games-Howell multicomparison post hoc test (α=.05).

RESULTS

The conventional direct modeling group had lower mean volume of the cementation space than all CAD-CAM composite resin post-and-cores (P<.041). The conventional indirect modeling group had a lower volume of the cementation space mean than PDC (P<.024) but was not significantly different from PIC (P=.577) or PSC (P=.221). Regardless of the fabrication workflow, no differences were observed among the CAD-CAM composite resin post-and-cores (P>.05). At the apical root third, conventional direct modeling and conventional indirect modeling had lower film thickness means than PSC or PDC (P<.05). In the middle third, conventional direct modeling and conventional indirect modeling had lower film thickness means than PDC (P≤.001). At the cervical third, no differences in film thickness means were observed among the groups (P>.05). PDC had a lower apical gap mean than PSC (P=.013), while no significant differences were found for other pair comparisons (P>.05).

CONCLUSIONS

Metal post-and-cores had slightly better adaptation than the CAD-CAM composite resin post-and-cores; however, the part-digital fabrication workflow of CAD-CAM composite resin post-and-cores provided adaptation parameters within a clinically acceptable range and is less time consuming.

Esthetic and functional consideration in restoring endodontically treated teeth

The selection of the best restoration for an endodontically treated tooth in the aesthetic zone depends on strength and the ability to recreate the form, function, and aesthetics of the natural tooth. The increased use of all-ceramic materials is a result of improved ceramic materials and adhesive systems. However, the advent of the current variety of translucent ceramic systems makes the shade of the abutment important in achieving the desired aesthetic outcome. This article discusses the different types of posts used in the restoration.