Influence of post placement on single unit full coverage restorations in endodontically treated teeth - A systematic review

Introduction

Significant loss of tooth structure occurs during the removal of caries, previous restorations, access cavity preparations and trauma during the endodontic treatment. 1 This can in turn compromise the tooth to withstand the functional loads.2 Excessive loss of tooth structure during the endodontic treatment results in very minimal tooth structure and inadequate ferrule leading to reduction in the clinical crown height which will compromise the retention of the post endodontic restoration.3 So in most of the cases post placement is suggested to retain the core for the better prognosis of the root filled teeth.4

But so many studies suggested that the radicular dentin removed during the post space preparation will further compromise the prognosis. The success of post-endodontic restorations is largely dependent on the degree of tooth structure loss and the presence or absence of a 2 mm circumferential ferrule.5

When making decisions in clinical dentistry, it is best to follow the evidence-based practice. In order to provide clinical recommendations based on evidence, it entails using trustworthy and verified methodologies to carefully examine all published data in a particular clinical setting.

Considering the endodontically treated teeth, the ideal approach to treatment planning is to look at the success and failure rates of each treatment strategy based on the risk factors. Finding published studies on the success, survival or failure rate of traditional single-unit restorations with and without post placement in permanent dentition is the primary goal of this systematic review.

Materials and Methods

This study followed the PRISMA declaration, the criteria of the Cochrane Collaboration, and the quality requirements put forth by AMSTAR for treatments while conducting its systematic review Liberati et al. 2009. 5 Moher et al. 2009; 6 Higgins & Green 2012;7 Shea et al. 2009.8 The systematic review was registered in the PROSPERO database: (CRD42023416326). By encouraging openness Faggion 2013, 9 quality approach Faggion 2010,10 and improved reporting Faggion 2012, 11 this was done to reduce the possibility of bias in the review process.

Results

The first database search yielded 4086 references. A total of 26 complete texts were considered for eligibility after titles and abstracts were screened and duplicates were removed (Figure 1). Information acquired from the six papers that were included in the analysis after full text reviewing is shown in Table 1.

Study by Mannocci et al. (2002) 15 revealed that at I-year recall, no failure was reported. The only failure modes observed at 2 and 3 years were post decementations and the presence of marginal gap formation. The observed failures were post decementation (1 from Group 1 and 2 from Group 2) and marginal gaps as revealed by radiographs (3 from Group 1 and 1 from Group 2). There was no difference between the number of post decementations or marginal gaps between the 2 groups (95% confidence intervals,-9.7 to 16.2 and-17.8 to 9.27). Bitter k et al (2009)16 in his study showed that after a mean observation period of 32.4 (13.7) months in subgroups no post, the failure rates were 10%, whereas in subgroups post, failure rates of 7% were observed. In no-wall group post placement significantly affected the time to failure of total restorations. Teeth without post retention revealed a significantly higher failure rate (31%) compared with teeth restored with post retention (7%).

Ferrari et al (2012) 17 in his study revealed that the least satisfactory clinical performance was demonstrated by teeth restored without any intraradicular retention (Subgroup A: success rate 42.1%, survival rate 85.9%). Success rate with post [4 coronal walls -100% (BOTH LP and ES);3 coronal walls -94.1%(LP), 76.5%(ES); 2 coronal walls -88.9%(LP), 66.7%(ES); 1 coronal wall -77.8%(LP), 50.0%(ES), Ferrule present –61.1%,28.5%-Ferrule absent,38.9%(LP), 31.6%(ES)] Success rate without post [4 coronal walls-100%, 3 coronal walls-66.7%, 2 coronal walls- 52.9%, 1 coronal wall-29.4%; Ferrule present -11.1%; Ferrule absent-0%].

Study by K A Guldener et al (2017) 18 showed that the overall tooth survival ratewas 89.6%.Thesurvival rate was 94.3% for teeth with a fiber post and76.3%for teeth without a post, respectively. 106 teeth (73.6%) were restored with a fiber post and either a single-unit crown (SUC) or a direct composite restoration (DCR). Teeth without a post (n=38, 26.4%) were restored either with an SUC or a DCR. Teeth restored with a fiber post yielded a statistically significantly (P<.001) higher survival rate compared with teeth restored without a post, irrespective of the restoration type.

Cloet et al(2017)19 in his study showed that of the restorations, 49.3%(n=101) were cast gold alloy based post and cores, 32.0% (n=65) were prefabricated glass fiber posts with composite cores, 12.8% (n=26) were custom made glass fiber posts with composite cores ,and 5.9% (n=13) were composite cores without posts. Success rate with Prefabricated wrought posts-86.9%, Prefabricated glass fiber posts- 81.6%, Custom made glass fiber post -87.8%; Success rate without posts- 83.3%. Study by E.J. Kramer (2019) 20 in his study had 195 patients with a mean (95% CI) age of 54 (52 - 56) years and with 195 coronal restorations in ETT were included. Failure rate with posts [On anterior -55%, On premolars-24%; Based on proximal contacts (28%) 0-50%, 1-42%, 2-30%; Based on post material l(28%){Glassfiber-31%, Metallic-25%, Titanium (threaded)-30%, Titanium (stepped) 24%, On full crown-10%]

Figure 1

Prisma flow chart of study selection process

Discussion

Prognosis of endodontically treated teeth depends upon various factors like biomechanical preparation, increased or inappropriate usage of irrigants and intracanal medicaments and last but not the least the inappropriate placement of post endodontic restoration. Often we are in a dilemma whether to place a post or not to place a post after the endodontic treatment. There are so many clinical trials and invitro studies on evaluating the performance of different types of posts but their significance in the prognosis or reducing the failure rates in root filled teeth is very less. Thus, the purpose of this systematic review is to gather clinical data about the effects of post-retained and post-free full coverage restorations on teeth that have had endodontic treatment.

More than 991 patients who satisfied the inclusion criteria at baseline were analyzed in this systematic review, which comprised six trials totaling 229 anterior restorations and 910 posterior restorations. Additionally, the included studies had follow-up periods ranging from three to ten years.

Based on the research that were considered, it seems that placing posts is unnecessary when there are four remaining walls and that complete crowns are the optimum course of therapy. An increase in coronal tooth structure was associated with an improvement in the success rate. Research conducted by Mannocci et al., 15 Ferrari et al.,17 and K. A. Guldener et al., 18 on teeth with three remaining walls and complete crowns has not shown an improved success rate when installing a post at a 9-year follow-up.

According to research cited by E.J. Kramer, 20 Cloet et al., 19 and Ferrari et al., 17 the success rate of teeth treated with endodontics seems to be higher after seven years when restored with two remaining walls, a post is placed, and a complete crown is placed. The two remaining walls could not be enough to support the teeth and prevent crowns from falling out or other problems that might cause catastrophic or relative failures. It is recommended to use a post and then restore the whole covering when there are just two walls remaining.

Teeth with one or less than one remaining wall had a higher success rate when placing a post followed by full crown when compared with no posts with crown Bitter k et al 2009, 16 Ferrari et al 2012, 17 Cloet et al 2017, 19 Guldener et al 2017, 18 E J Kramer 2019. 20 Also Ferrari et al. (2012)18 concluded that teeth with crowns that had ferrule showed significant lower failure rates when compared with those crowns retained by posts which did not had the ferrule effect . In that scenario dental implants may be considered. Therefore teeth with one or less than one remaining wall with ferrule effect recommend the placement of post followed by full coverage restoration.

From three to ten years was the span of the follow-up duration for all the primary studies that were included. Both the front and back teeth were examined in the included studies. In addition, they lacked an abutment for a permanent or partial denture and had oppositional teeth. Studies that were considered had the flaw of focusing just on the total number of dentinal walls and ignoring their thickness and height. Furthermore, the sample sizes of the different groups are not appropriately distributed in these investigations. Clearly, the failure rates will be higher in the group with a larger sample size; for instance, if there are 20 teeth in the anterior group and 100 teeth in the posterior group. Thus, it is possible that this review's conclusions are not applicable to a broader context.

Patients' quality of life and healthcare expenditures may both be improved by providing them with the best possible post endodontic restoration Grol & Grimshaw 2003,21 Darmstadt et al. 2005. 22 When it comes to recommending a particular treatment choice, we find this systematic review to be lacking in quality. Post implantation requires additional tooth structure to be removed, increasing the risk of fracture and failure Balevi 2013.23 To conserve more coronal tooth structure, conservative access cavities should be constructed.

As a result, studies should be planned for the future to include bigger samples, appropriate treatment allocation, and long-term prospective data. Treatment implementation should occur in a variety of contexts (e.g., with students and physicians from both public and private practices), and failure should be reported using accurate and repeatable evaluations (e.g., USPHS evaluation methodologies).

Conclusion

A better prognosis for teeth treated endodontically is associated with a larger quantity of residual tooth structure. Therefore, the amount of coronal tooth structure that is preserved during conservative access cavity preparations will determine the post endodontic restoration. It seems that intracoronal restorations, post-free crowns, and post-retained crowns are the three best treatments.Although post-retained crowns are better, post-free crowns may be considered when three or four tooth walls are still present, whereas teeth with one or two remaining walls may be better candidates for post-retained crowns. In situations when the ferrule is absent, other prosthetic components may be explored.

Source of Funding

None.

Conflict of Interest

None.