Comparative evaluation of the effect of endodontic access and subsequent restorations on crown retention: A narrative review of an in vitro study

Reem Mahmoud; Arruh Almolhem; Sawsan Alomari; Rahaf Babader; Faisal Alghamdi

doi:10.4103/sej.sej_74_22

REVIEW ARTICLE

Year : 2023 | Volume : 13 | Issue : 1 | Page : 22-27

Comparative evaluation of the effect of endodontic access and subsequent restorations on crown retention: A narrative review of an in vitro study

Reem Mahmoud¹, Arruh Almolhem¹, Sawsan Alomari¹, Rahaf Babader¹, Faisal Alghamdi²
¹ Department of General Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
² Department of Oral Biology, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia

Date of Submission	24-Apr-2022
Date of Decision	28-May-2022
Date of Acceptance	29-May-2022
Date of Web Publication	11-Jan-2023

Correspondence Address:
Dr. Faisal Alghamdi
Department of Oral Biology, Faculty of Dentistry, King Abdulaziz University, 80209, Jeddah 21589
Saudi Arabia

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/sej.sej_74_22

Abstract

Studies suggest that endodontic access cavity (EAC) can decrease the retention of crowns. However, there is no clear evidence that restoring EAC effects on crown retention. Thus, the main objective of this narrative review is to assess several materials applied for restoring EAC to different crowns in anterior or posterior teeth, as well as the effect of each material on crown retention. An electronic search for studies published until December 31, 2021, was conducted using the four databases: Scopus, PubMed, Web of Science, and Google Scholar. Researchers selected in vitro studies that investigated the crown retention before and after resorting EAC of anterior or posterior teeth. Exclusively, in vitro studies were considered for assessment. Five papers were selected for the final analysis from the 126 identified during the initial search. Our outcomes illustrated that no significant differences in outcomes between the restorative materials after the endodontic treatment. The findings of this narrative review suggest that crown retention can increase after restoring endodontic access cavities. Finally, the available data indicated that restoring EAC could increase the crown retention more than the original crown. Nevertheless, the prefabricated crown resistance could be more affected by the type of restorative material used inside the EAC following endodontic treatment than retention. Additional clinical and radiological measures are needed.

Keywords: Cavity preparation, crown, pulp chamber access, restorative materials, retention

How to cite this article:
Mahmoud R, Almolhem A, Alomari S, Babader R, Alghamdi F. Comparative evaluation of the effect of endodontic access and subsequent restorations on crown retention: A narrative review of an in vitro study. Saudi Endod J 2023;13:22-7

How to cite this URL:
Mahmoud R, Almolhem A, Alomari S, Babader R, Alghamdi F. Comparative evaluation of the effect of endodontic access and subsequent restorations on crown retention: A narrative review of an in vitro study. Saudi Endod J [serial online] 2023 [cited 2023 Mar 22];13:22-7. Available from: https://www.saudiendodj.com/text.asp?2023/13/1/22/367519

Introduction

The teeth are effectively kept in 95% of patients for at least 5 years, if the teeth have been fully restored with full coverage crowns.^[1] In some conditions, the pulpal disease can occur in vital teeth with crowns.^[2] A functional, esthetic, and undamaged margined teeth are making the crowns accessible for endodontic treatment might not need replacement and may frequently be restored.^[3],[4]

When endodontic therapy is required, the dentist can get access to the root canal system by preparing a typical endodontic access cavity (EAC) in the crown. Previous investigations.^[5],[6],[7] have found a reduction in crown retention after preparing endodontic access cavities of crowns on central and lateral incisors. They also proved that after filling these cavities with amalgam, the original crown retention was restored, if not exceeded. Furthermore, two investigations have been conducted on the consequences of access cavities and their subsequent restorations in permanent molar crowns.^[4],[8]

Crown retention is determined by the casting's fit, the action of the luting cement, the degree of taper of the axial walls, and the surface area of the crown preparation, with the axial walls supplying the majority of the retention.^[9] The established of an EAC through an existing crown eliminates a portion of the dentine core that supports the restoration, which may result in a possible lack of retention.^[5],[6],[7] The access cavity in molar teeth is established by the occlusal surface of the tooth which is not an axial wall. As a result, its impact on the crown's retention is not expected to be significant.^[4],[8]

To reestablish access openings in crowns accessible for root canal therapy, a variety of materials are applied. A previous investigation indicated that the displacement force of high palladium/low gold crowns in accessed crowns was much reduced.^[4] According to the findings of that investigation, restoration using either glass ionomer cement (GIC) or amalgam contributed to high in the original value for retention.^[4]

This first review discusses the retention between materials applied to restore an anterior or posterior crown with an endodontic access of in vitro studies. There have been no previous studies that observed at the effect of EAC with various restorations on crown retention. Thus, this narrative review investigated several materials used for restoring EAC to different crowns in anterior or posterior teeth, as well as the effect of each material on crown retention by evaluating the available in vitro studies.

Materials and Methods

Literature search strategy

Four reviewers did their own electronic searches in the following databases: Scopus, PubMed, Web of Science, and Google Scholar. The following key terms were used: ([endodontic access] OR [access cavity]) AND ([restorative material] OR (restoration) OR [amalgam] OR [composite]) AND ([crown] OR [retention] OR [crown retention]). Publications in the English language published with no time restrictions. The end of the electronic search process was done on December 31, 2021. The reference lists of the selected papers were analyzing to identify other relevant papers.

Inclusion and exclusion criteria

The present review was designed to identify in vitro studies that assessed the several materials used for restoring endodontic access to different crowns in anterior or posterior teeth and their effect on crown retention. Exclusively, published in vitro studies with no time restrictions were identified and analyzed. To be included, a study must include a sample size of human teeth only, investigated the crown retention of un-restoring/restoring of the endodontically treat teeth in comparison with the original crown retentive force.

The exclusion criteria included reviews, case reports, observational studies, and in vivo/ex vivo studies; studies with an unclear sample size selection protocol; and studies that investigated other parameters than the crown retention and used artificial teeth.

Data extraction

A flowchart of the search process and excluded/included articles was developed [Figure 1]. Following the initial screening of all identified publications based on the title and abstract, the same four reviewers evaluated the full text of each article to be included. For each included study, the following information was entered into a Microsoft Excel spreadsheet: Mean value of crown retention force, type of restoring EAC, type of crown, type teeth used, sample size, and main outcomes. Four reviewers examined all the selected papers individually. Discrepancies were managed through discussion with a fifth reviewer.

Figure 1: A flowchart of the search process and study selection

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The data were entered into two tables. One table was designed for study characteristics and the second table was designed for the distribution of mean values of crown retention force with different restorations before and after restoring EAC. Different data items including sample size, country, main outcomes, mean value of crown retention force, type of crown, type teeth used, and type of restoring EAC were collated. All the results were presented as descriptive data only.

Results

Study selection

Initially, 126 papers were collected through the use of keywords in databases. Of those, 28 were removed because of duplication or an irrelevant topic. Only 98 papers were screened, and 47 were considered eligible. A total of 42 full-paper articles were removed from the eligibility due to the following reasons:

Systematic, narrative, or critical reviews (n = 2)
Case report studies (n = 2)
Observational studies (n = 14)
In vivo studies and ex vivo studies (n = 6)
Considers artificial teeth or animal teeth (n = 9)
Studies were not investigated the other parameters than crown retention (n = 8)
Study with unclear sample size selection protocol (n = 1).

Finally, five publications were chosen to be involved in this narrative review [Figure 1] summarizes the literature search strategy used for this study.

Study characteristics

All the included studies^{[4],[5],[6],[7],[8]} were conducted in different countries, including two studies in Australia^[4],[7] and three in the United States.^[5],[6],[8] In total, 111 human teeth were included. Regarding the type of teeth, two studies were molars,^[4],[8] while three were incisors.^[5],[6],[7] Only one study included teeth with unrestored EAC and compared with intact teeth.^[5] The other four studies investigated teeth after restoring EAC with different restorations such as amalgam,^{[4],[6],[7],[8]} composite,^[8] and GIC.^[4] Regarding the crown type, four studies^{[5],[6],[7],[8]} were porcelain fused to metal (PFM) crown, while one study was vented metal copings.^[4] The main outcomes illustrated unrestored EAC decreased the crown retention compared to the original retention value in all the included studies [Table 1]. On the other hand, restored EAC illustrated increased the crown retention with different retentive force values [Table 1].

Table 1: An overview of the characteristics of the involved articles

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The mean values of crown retention with different restorations

In all the included studies, crowns were cemented with zinc phosphates cement^{[4],[5],[6],[7],[8]} or zinc polycarboxylate cement^[6] according to the manufacturer's instructions. All teeth were subjected to different retentive force loads to the point of occlusal surface using a tensile testing machine.^{[4],[5],[6],[7],[8]} The mean values of crown retention with different restorations were recorded to compare these mean values before and after the restoring of EAC with the original retentive force values. The original retention value of the five selected studies ranged from 7.50 kg forces to 100.00.^{[4],[5],[6],[7],[8]} At unrestored EAC, the retentive force values ranged from 4.60 kg force to 91.19.^{[4],[5],[6],[7],[8]} Furthermore, these values of unrestored EAC were less than the original retentive force values.^{[4],[5],[6],[7],[8]} Thus, unrestored EAC decreased crown retention compared to the original retentive force values in all the included studies [Table 2]. On the other hand, restored EAC with different types of restoration, the retentive force values ranged from 21.70 kg force to 194.92 [Table 2]. Furthermore, these values of restored EAC were more than the original retentive force values [Table 2]. Thus, restored EAC increased the crown retention to more than before the endodontic treatment was performed (original retentive force value) in all the included studies [Table 2].

Table 2: Distribution of mean values of crown retention force before and after restoring endodontic access cavities

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Discussion

It is preferable to insert the restorative material in the EAC immediately after endodontic therapy was performed. Even though a rubber dam is the requirement of infection control for endodontic therapy, restoring crown access directly after endodontic treatment saves the patient time and reduces the risk of contamination, as indicated by Heling et al.^[10]

According to the findings of this narrative review, an EAC reduces the displacement force of a crown and the insertion of a restorative material in EAC surpasses the original retention.^{[4],[5],[6],[7],[8]} The outcomes of this narrative review indicate that GIC, amalgam, and composite restorations increased the retentive force of vented metal copings^[4] and PFM crowns^{[5],[6],[7],[8]} compared to the original retention value, but these materials illustrated no significant difference between them in most of these selected studies.

In the current review, the access area for each sample was recorded before and after restoration in four out five included studies.^{[4],[6],[7],[8]} However, two out of five selected investigations enhanced the displacement force by “linking” the material in the access to that found in the root canal space using a ParaPost.^[7],[8] There is evidence that posts help with tooth fracture resistance.^{[11],[12],[13],[14],[15],[16],[17]} Cagidiaco et al.^[18] found that fiber posts considerably increase the survival rate of endodontically treated restored premolars in a 3-year randomized clinical trial.

Another randomized clinical trial study discovered that fiber post insertion decreased the chance of failure in endodontically treated premolars.^[19] It was also shown that the forces needed to displace anterior crowns following postretained amalgam restorations were greater than the forces needed to displace the crown after restoring the EAC only with amalgam restoration.^[7]

This narrative review only investigated the crown retention and not resistance in all the included investigations.^{[4],[5],[6],[7],[8]} In a newly published in vitro study, Alghaithi and Martin studied fracture resistance rather than crown retention.^[20] They reached the conclusion that restoring endodontically treated teeth with full-coverage crowns can help avoid residual tooth structure breakage and maintain remaining tooth tissue.^[20] As a result, additional research is needed to analyze the resistance as a factor that may have an influence on the crown after restoring the EAC.

In the present review, the findings indicate that placing a post and amalgam^[7] or composite^[8] in a PFM access enhanced retention compared to the original force. Nevertheless, the retention force was greater when the restorative material was used alone. The findings are not surprising given that bond strengths to posts consider significantly low.^[21]

All the selected in vitro studies^{[4],[5],[6],[7],[8]} demonstrated that there have been no great disparities in result among the restorative materials after the endodontic treatment. The findings of this narrative review suggest that crown retention may be increase after restoring EAC. All five papers showed low retentive force of unrestored EAC compared to the original retentive force [Table 2].

There are some limitations. This narrative review included only five in vitro studies. The type of final restoration (amalgam, composite, and GIC) differed between the studies. Regrettably, there was insufficient information to investigate the artificial aging of materials/samples as a potential prognostic factor. In this review, the only identified prognostic factor was retentive force of crown.

Conclusions

According to the findings of this narrative review, an EAC reduces the retention of a metal coping/PFM crown. In addition, restoring EAC could increase the crown retention more than the original crown retention. Nevertheless, crown resistance could be more influenced by the type of restorative material used inside the EAC following endodontic treatment than retention. More human clinical and radiographic studies to further assess the effectiveness of crown resistance are warranted.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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